PhD, M. Tech. & M. Sc Thesis and Dissertations · M. Tech. & M. Sc Thesis and Dissertations ... Displacement based design framework for confined masonry system ... Effect of strain

List of

PhD, M. Tech. & M. Sc

Thesis and Dissertations

(Abstracts)

Prepared by

LIBRARY Indian Institute of Technology

Gandhinagar Feb. - 2016

PhD Thesis and Dissertation

Contents Chemical Engineering ..............................................................................................................

Hydrodynamic, mixing and mass transfer characteristics of multiphase reactors ..............

Hydrodynamics of solid-liquid fluidized beds: modelling and experimental studies ...........

Quantification of acetone-butanol-ethanol(ABE) fermentation in clostridium

acetobutylicum using systems biology approach .................................................................

Chemistry ................................................................................................................................

Synthesis and Photoinduced Processes of Donor-Acceptor Substituted Diarylbutadienes.

Electrical Engineering ..............................................................................................................

Characterizing high-frequency behaviour of transformer by reduced-order circuit model

and assessing the severity of mechanical deformations ......................................................

Controls for Moderating Generation-Demand Mismatch in Wind-Solar-Hydro Energy

Conversion Systems ..............................................................................................................

Grid converter synchronization techniques for distributed generation systems ................

HSS (Cognitive Science) ............................................................................................................

Role of attentional scope on altruistic decisions ..................................................................

Role of sensory prediction on perceptual and motor mechanisms .....................................

Humanities & Social Sciences ...................................................................................................

Gender Politics and Indian Children’s Literature: A Comparative Analysis of Adventure

Fiction in English and Gujarati ..............................................................................................

Physics ....................................................................................................................................

Effects of lower atmospheric and solar forcings on daytime upper atmospheric dynamics

Finite Temperature Effects in the Condensates of Dilute Atomic Gases .............................

Inflationary scenario with non- standard spinors .................................................................

Spectral and Timing Studies of Accretion Disk in Black Hole Binaries ..................................

Stable water isotopologues in the Indian summer monsoon rainfall ..................................

Vortices of light and their interaction with matter ..............................................................

M. Tech. & M. Sc


Contents Chemical Engineering ..............................................................................................................

Morphology and optical properties of nanoparticle thin films fabricated by spread

coating ...................................................................................................................................

Design of an evaporator for vaporization of glass forming silica precursor.........................

Colloidal particles self-assembly in liquid crystals ................................................................

Modeling of microbubble dissolution in aqueous medium..................................................

Protein-polysaccharide nano-complexes at air water interface ..........................................

Computational assessment of air pollution dispersion in urban centers .............................

Experimental study of Bechamp process for nitrobenzene reduction to aniline ................

Experimental study of Bechamp process for p-nitrotoluene reduction to p-toluidine........

Numerical study of thermophoretic deposition of nano-silica using outside vapor

depositon ..............................................................................................................................

Hydrogen Production Via Catalytic Partial Oxidation Of Methane On Lanthanum Oxide

and Nickel-Lanthanum Oxide Catalysts ................................................................................

Colloidal Rhombohedral Particles in Hexagonal Liquid crystal: - Rheology and

Microstructure ......................................................................................................................

Model Predictive Control Strategy for Optimizing Biological Nitrogen Removal (BNR)

Processes Accounting for Greenhouse Gas Emissions .........................................................

Kinetic Study and Advanced Control of Bechamp Reduction of p-Nitrotoluene Process in

a CSTR ....................................................................................................................................

Ultrasonication Assisted Synthesis of Few Layers Thick Chemically Modified Magnesium

Diboride Nanosheets ............................................................................................................

Aspects of Liquid Antisolvent Precipitation of Nanoparticles of Poorly Water Soluble

Drugs: Nucleation Kinetics, Precipitation Pathways and Long Term Stability ......................

Decomposition Kinetics of CaCO3 Dry Coated with Nano-Additives ...................................

Physico-Chemical Interaction of MgB2 with Water during Ultrasonication: An Avenue to

Realize Boron-Rich Quantum Dots, Nanodiscs, and Nanoplatelets .....................................

Integrating production control and scheduling based on real-time detection of

divergence .............................................................................................................................

Water sustainability and re-use: a case study at Amul Dairy, Anand ...................................

Civil Engineering ......................................................................................................................

Mechanical Behavior of Slurry Consolidated Specimens of Cement Treated Soft Soil

Using Shear Strength and CRS Consolidation Testing ..........................................................

Estimation of Linear Spring Constant for Laterally Loaded Monopile Embedded in

Nonlinear Soil ........................................................................................................................

Shear Strength and Compressibility Behavior of Bhavnagar Expansive Soil with Varying

Mineralogical and Swelling Properties .................................................................................

Effect of Water Content on Shear Strength Behaviour of Micaceous Kutch Soil .................

Response of Smartphones to Roadway Surface Irregularities .............................................

Strain influence diagram for estimation of settlement of isolated and combined ring

footings .................................................................................................................................

Landslide susceptibility mapping using GIS ..........................................................................

Estimating dynamic response from pushover type analysis through a semi-empirical

approach ...............................................................................................................................

Design of a new passive energy dissipation system for earthquake resistant structures ...

Development of novel web application for analysis, design and optimization of trusses ...

GPR Data Analysis of Weak Signals and GPR Investigation at Dholavira Site .......................

Displacement based design framework for confined masonry system using strut and tie

model ....................................................................................................................................

Effect of strain rate on shear strength and pore pressure behavior of soft soil ..................

Bed Rock Profile Analysis and Interpretation of Archaeological Features Using GPR at

Dholavira ...............................................................................................................................

Characterization of in-plane and out of -plane behavior of infill panels subjected to

thermal exposure ..................................................................................................................

Investigation of moisture transport properties of FAL-G bricks and cement ......................

Effect of agar biopolymer on shear strength behaviour of Sabarmati soil ..........................

Cognitive Science .....................................................................................................................

Effect of Paced Respiratory Exercise on Retention of Motor Skills ......................................

Electrical Engineering ..............................................................................................................

Design of High Resolution Low Power ADC ..........................................................................

Online Health Monitoring of the Polymer Electrolyte Membrane Fuel Cell ........................

Behavioral analysis of control room operator during plant operation using display

interaction and eye gaze information for effective plant monitoring..................................

Effect of Device Geometries on HCI and PBTI of Gate First High-K Metal Gate NMOS

Transistors .............................................................................................................................

Design and Finite Element Analysis of Micromachined Piezoresistive Polyimide

Nanocantilevers for Surface Stress Sensing Applications .....................................................

A Step towards Developing a Virtual Reality Based Rehabilitation System for Post-Stroke

Hand Movement Disorder ....................................................................................................

Analysis and Modeling of Stress Overlayer Induced Threshold Voltage Shift in High-K

Metal Gate MOSFETs ............................................................................................................

Evaluating the Scaling Effects on Synchronizers and Global Interconnects in Multicore

SoCs .......................................................................................................................................

Terahertz detection with CMOS: Simulation Studies ...........................................................

Frequency Driven Alteration In Cellular Morphology During Ultrasound Pulsing In A

Microfluidic Confinement .....................................................................................................

Demand Response Algorithm Incorporating Electricity Market Prices for Residential

Energy Management .............................................................................................................

Outage Management System for Power Distribution Network ...........................................

Dynamic Modelling Based Reference Current Extraction Technique for the Control of

Shunt Active Power Filter .....................................................................................................

A Novel Active Anti-Islanding Protection Scheme for Grid-Interactive Roof-Top Solar PV

Systems .................................................................................................................................

Power Flow Control of Hybrid AC-DC Microgrid using Master-Slave Control Technique ....

Finite Control Set MPC based Distribution Static Compensator (DSTATCOM) for Load

Compensation .......................................................................................................................

Least Distance Predictor Model for Short Term Load Forecasting .......................................

Towards a wearable non-invasive low-cost device for measuring physiological indices:

one touch doctor ..................................................................................................................

A step towards developing an intelligent psychophysiology based computer assisted

interactive system .................................................................................................................

Design and Implementation of Efficient Neuromorphic Architectures ................................

Study of Variability and Technology Scaling on Synchronizers and Design of Metastable-

hard Synchronizers................................................................................................................

Design of complementary high-voltage device compatible with SCL`s 0.18 um CMOS

technology ............................................................................................................................

Experimental investigation of DC-link capacitor voltage balancing in neutral point

clamped inverter ...................................................................................................................

Analysis of Gate Leakage Current in High-k Metal Gate MOS Transistors ...........................

Material Science and Engineering ............................................................................................

Improvement of overall equipment effectiveness (OEE) of alumium foil rolling mill ..........

Processing and Characterization of Pcl-Ha Composites for Medical Application ................

Mathematical medaling of heat transfer, fluid flow and solidification in melt spinning

process ..................................................................................................................................

Evaluation of Forming Limit Diagram of Aluminum alloy 6061-T6 at Ambient

Temperature .........................................................................................................................

Formability characterization of AI6014 and DP600 alloys considering the effects of non

linear strain paths, temperature and bending .....................................................................

Thermodynamics of ultra-thin oxide overgrowths on binary Al-based alloys .....................

FEM and Experimental Evaluation of J-Integral for Multi-phased Materials. ......................

New tool design for friction stir weilding of polymer ...........................................................

Rheological studies of coal fly-Ash slurries ...........................................................................

Comparative study of fatigue crack growth rate of SS 304H Cu for two different heats.....

Evaluationm of Hoop direction tensile properties of 9cr-ODS and T91 steel nuclear fuel

clad tubes using ring tensile test ..........................................................................................

Mechanical Engineering ...........................................................................................................

Computational Aerodynamics and Flight Dynamics of Perching Maneuver of Unmanned

Aerial Vehicles .......................................................................................................................

Design And Performance Calculation of a Solar Aided Super Critical Coal Power Plant

with Thermal Energy Storage................................................................................................

Computational Modeling of the Condensed Phase Aerosol Based Fire Extinguisher ..........

Computational Modeling of Wing In Ground Effect Aerodynamics .....................................

Recursive and Delayed Reconstruction of Unknown Inputs for Dynamical Systems ...........

CFD Based Coal Combustion and Erosion Modelling for A 660 MWE, Super-Critical

Tangentially Fired Pulverized Coal Boiler .............................................................................

Computational Modelling of Positive Displacement PumpsBoiler .......................................

High- fidelity computational assessment of the performance of a vertical axis wind

turbine ...................................................................................................................................

Impact of fan pressure change and rack layout on data center thermal performance .......

Lattice Boltzmann method for applied aerodynamics problems .........................................

PhD

Thesis and Dissertation (Abstract)

Chemical Engineering

Title : Hydrodynamic, mixing and mass transfer characteristics of multiphase

reactors

Researcher : Kalaga, Dinesh Kumar

Supervisor : Joshi, J. B. and Dalvi. Sammer V.

Department : Chemical Engineering

Year : 2015

Pages : 317

Call No. : 660.2 KAL

Acc. No. : T00058

Keywords : Hydrodynamic; Solid-liquid fluidized bed; Residence time distribution;

Radioactive particle tracking; Computational fluid dynamic; Mixing & Mass

transfer

Abstract : The multiphase reactors such as solid-liquid fluidized beds and bubble

columns are widely used chemical, petrochemical and allied industries. Their

application ranges from manufacturing processes such as catalytic

hydrogenation, oxidation, fermentation, waste water treatment, Fischer-

Tropsch Synthesis and Chromatographic separations etc. The performance of

these multiphase reactors depends on hydrodynamic, mixing and mass

transfer characteristics. With this objective, in the present research work, an

attempt has been made to understand the rational design procedures for

multiphase reactors such as solid-liquid fluidized bed (SLFB), Solid-liquid

multistage fluidized bed (SLMFB), Solid-liquid circulating multistage

fluidized bed (SLCMFB) and Bubble column reactors.

Liquid phase residence time distribution (RTD) studies have been performed

in conventional SLFB and SLCMFB. RTD experiments for SLFB were

carried out in the column having the same diameter as the downcomer of

SLCMFB. RTD has been estimated for both the riser column and the

multistage downcomer column of SLCMFB. Computational fluid dynamic

(CFD) simulations of SLFB and riser section of SLCMFB have been

performed to predict the RTD. In all the above cases, good agreement was

found between the CFD predictions and the experimental measurements.

Based on the experimental data, empirical correlations have been proposed for

liquid phase axial dispersion coefficient.

Solid-liquid mass transfer coefficient (kSL) was measured in both

conventional SLFB and SLMFB by using the system of dissolution of benzoic

acid in water. The dependence of kSL on important variables associated with

the distributor design and the effect of inerts has also been studied. Based on

the experimental data, generalized correlation has been proposed for the

estimation kSL for both SLFB and SLMFB.

Radioactive Particle Tracking (RPT) technique was employed to quantify the

hydrodynamic parameters in 120 mm diameter bubble column with and

without internals using air/water systemat different superficial gas velocities

ranging from 15 mm/s to 265 mm/s. Experiments were performed for two

internal configurations with percentage obstruction area in the range from 0

(no internals) to 11.7%. It is found that, the liquid phase hydrodynamics

depends strongly on the superficial gas velocity and the internals. Suggestions

have also been made for the future work.

Title : Hydrodynamics of solid-liquid fluidized beds: modelling and

experimental studies

Researcher : Ghatage, Swapnil Vilasrao

Supervisor : Joshi, Jyeshtharaj and Padhiyar, Nitin


Year : 2014

Pages : 289

Call No. : 660 GHA

Acc. No. : T00055

Keywords : solid-Liquid; Hydrodynamics; Petrochemical and process; computational fluid

dynamic (CFD); fluidized beds; solid‐liquid fluidized bed; kinetic theory;

modelling studies

Abstract : Fluidized beds are widely used in chemical, petrochemical and process

industries. They are preferred over other reactors for carrying out various

gas‐solid, solid‐liquid and gas‐solid‐liquid processes due to enhanced contact

between the fluid and solid particles. However, the efficient operation of a

fluidized bed requires the accurate choice of design and operating conditions

and the accuracy of prediction of fluidization behaviour. With the

developments in sophisticated measurement techniques and computational

methods as well as increasing computational power, the detailed study of

fluidized bed hydrodynamics is increasing extensively. In view of this, as a

first exercise, the published literature on the hydrodynamics of these

equipment has been systematically analyzed. The advances made in the

experimental, modelling and simulations have been critically reviewed. The

present status of application of computational fluid dynamic (CFD)

simulations has been brought out.

In three‐phase sparged reactors such as fluidized beds and slurry bubble

columns, gas is sparged in the form of bubbles. The gas phase flows in one of

the two hydrodynamic regimes namely homogeneous or heterogeneous. The

performance is known to depend strongly on the regime of operation. The

estimation of critical gas holdup at which transition from homogeneous

regime to the heterogeneous regime occurs is crucial for the design and scale‐

up of sparged reactors. A number of experimental and empirical studies are

published in the literature; however, there exists a need of studies on

athematical modelling. In the present work, the theory of linear stability has

been used to develop a mathematical model for the prediction of regime

transition over a wide range of bubble size (0.7 to 20 mm) and terminal rise

velocity (80 to 340 mm/s), particle settling velocity (1 to 1000 mm/s), particle

concentration (0.0007 to 30 vol%) and slurry density (800 to 5000 kg/m3). It

was observed that the developed model predicts the transition gas holdup

within a standard deviation of 12 per cent for three‐phase sparged reactors. It

was also observed that the developed generalized stability criterion predicts

the regime transition in gas‐liquid two‐phase systems satisfactorily within 10

per cent. In multiphase systems involving a dispersed phase, such as fluidized

beds, the interphase exchange of mass, heat and momentum transfer can be

very different from those from a single particle, droplet or bubble moving

under terminal conditions. However, most existing methodologies still rely

heavily on empirical relationships. In this study the hindered settling/rising

(slip) velocity of single steel particles (dPD = 5 to 12 mm) and single air

bubbles (dB = 1 to 4 mm) has been measured in a solid‐liquid fluidized bed of

uniform size borosilicate glass beads (dP = 5 and 8 mm) as a function of

superficial liquid velocity. The homogeneity and intensity of the turbulence

within the fluidized bed has been quantified using article image velocimetry

(PIV) and on the basis of the classification velocity of the foreign (steel or

bubble) particle. It was found that the turbulence resulted in an increase in

the computed drag coefficient under all the experimental conditions covered

in this work. Eulerian‐Eulerian simulations of a monodisperse solid‐liquid

fluidized bed (SLFB) have been carried out to study the effect of turbulence in

SLFB on motion of the settling particle. The motion of foreign settling

particle has been studied by the dynamic mesh technique provided in

FLUENT 14.0. The results show that the model can satisfactorily predict the

terminal settling velocity at lower fluidization. The possible reasons for

deviations at high voidages have been explained. Also, computational fluid

dynamics‐discrete element method (CFD‐DEM) has been applied for the

simulation of the motion of foreign dense particle introduced in a

onodispersed SLFB. The fluidization hydrodynamics of SLFB, settling

behaviour of the foreign particle and particle‐particle collision effects have

been investigated. Compared to those predicted by empirical correlations, the

particle classification velocity predicted by CFDDEM provided better

agreement with the experimental data (less than 10% deviation). The

dimensionless collision frequency obtained by CFDDEM was found to agree

with those predicted by the kinetic theory for granular flow (KTGF). The

particle collision frequency was found to increase with an increase in the

particle size ratio (dPD/dP) and become independent of the foreign particle

size for high solid fractions. A correlation describing the collision force as a

sole function of the average bed voidage was developed having a maximum

error less than 20% in the prediction of particle collision force for dPD/dP ≤

2.

In many industrial‐scale fluidized‐bed reactors, particle mixing and

segregation play a vital role in determining the reactor performance.

However, there exists a lack of studies wherein the fluidization of systems

involving more than two types of particles is involved. Such systems are of

high industrial importance in mineral and chemical process industries.

Therefore, it was thought desirable to study the coupling between superficial

liquid velocity and a multi‐size (and/or multi‐density) particle systems

consisting of more than two types of particles. In the present work, Eulerian‐

Eulerian simulations have been carried out to investigate the effect of particle

density and diameter on the minimum fluidization velocity, segregation and

intermixing behavior in a fluidized bed comprising of three to five different

types of solid phases. It was observed that the Eulerian‐Eulerian model can

satisfactorily predict the fluidization characteristics in multi‐component

fluidized bed including the minimum fluidization velocity.

The stability analysis of multiphase reactors has been the focus of research for

the past few decades. In the present work, the regime transition in SLFB has

been analyzed using various experimental (PIV and measurement of settling

velocity) and modelling (1D linear stability, 3D CFD and 3D DEM) methods.

The characterization of turbulence in SLFB through these methods has been

used to provide an insight into the mechanism of momentum transport and

hence the transition. The transition conditions obtained using different

approaches have been compared. The relative advantages and limitations of

each method have been clearly brought out.

Recommendations have been made for the estimation of some of the design

parameters for SLFB. Suggestions have been made for the future work in the

area of experimental and modelling studies.

Title : Quantification of acetone-butanol-ethanol(ABE) fermentation in

clostridium acetobutylicum using systems biology approach

Researcher : Kumar, Manish

Supervisor : Saini, Supreet and Gayen, Kalyan


Year : 2015

Pages : 216

Call No. : 660 KUM

Acc. No. : T00095

Keywords : Clostridium; acidogenesis; solventogenesis; kinetic; Elementary Mode

Analysis; Acetone-Butnanol-Ethanol

Abstract : Clostridium acetobutylicum exhibits a two-step metabolic pathway where

substrates are first converted to organic acids accompanied by a decrease in

pH. The acids are then assimilated to organic solvents. The transition from

the acid-producing (acidogenesis) to the solvent-producing phase

(solventogenesis) is controlled by integration of a number of cellular and

environmental cues, whose precise mode of action are not well understood. In

this study, a series of batch experiments were performed to understand the

impact of extracellular cues in regulating the dynamics of acidogenesis and

solventogenesis. It is demonstrated that the two phases operate independently

of each other and the growth phase of the cell, i.e. the cues controlling a phase

are not linked to the status of the other phase or the growth phase of the cell.

Kinetic experiments demonstrated that there exist two previously

uncharacterized negative feedback loops controlling the amounts of acids

produced in the acidogenesis phase. In the next investigation of this work, we

have used Elementary Mode Analysis (EMA) to quantify fluxes of metabolic

network of C. acetobutylicum under different physical and chemical

conditions. Biochemical reactions and their stoichiometry based metabolic

model helped to reveal that, in response to external stresses, the organism

invokes Elementary Modes which couple acidogenesis and solventogenesis.

This coupling leads to the organism exhibiting physiological characteristics

of both, acidogenesis and solventogenesis at the same time. Significantly, this

coupling was not invoked during any ‘‘unstressed’’ conditions tested in this

study. Overall, this work highlights the flexibility in C. acetobutylicum to

modulate its metabolism to enhance chances of survival under harsh

conditions.

During this thesis work, we have also developed a pH based

phenomenological model of fermentative production of butanol from glucose

using C. acetobutylicum in batch system. The model relates the dynamics of

growth and metabolite production with the extracellular pH of the media and

was validated using data from a number of fermentation experiments, and was

found to be successful in predicting the fermentation dynamics in C.

acetobutylicum. Further, the proposed model can be extended to represent

the dynamics of butanol production in other fermentation system like fed-

batch or continuous fermentation using single and multi-sugars.

Chemistry

Title : Synthesis and Photoinduced Processes of Donor-Acceptor Substituted

Diarylbutadienes

Researcher : Agnihotri, Harsha

Supervisor : Gundimeda, Sriram Kanvah

Department : Chemistry

Year : 2015

Pages : 142

Call No. : 540 AGN

Acc. No. : T00097

Keywords : Donor; Diarylbutadienes; Hydrochloric acid; Dimethylformamide;

Ultraviolet-visible; Correlated Spectroscopy

Abstract : Several donor-π-acceptor systems based on diarylpolyene scaffold were

synthesized and examined for their fluorescence and photochemical

properties. The fluorescence investigations of these dienes reveal weak to

strong solvatochromism attributed to intramolecular charge transfer (ICT).

The systems containing nitro as acceptor, exhibit very weak quantum yields.

Changing the position of nitro group from para, meta or to ortho results in

further loss in emission. Interestingly, simple para (or meta) nitro

diarylbutadienes show inefficient photoisomerization. However, introduction

of a methyl group on the double bond in the same system yields regioselective

isomer of methyl substituted double bond. Likewise presence of nitro group

at ortho position also yields regioselective isomer of the double bond distal to

the aromatic nitro group. Such behaviour is explained by (a) steric effect of

methyl group that induces non-planarity and (b) the intramolecular C − H …

. O hydrogen bonding that inhibits the isomerization of the proximal double

bond. Similar photoisomerization observations were seen with a pyridyl

group in place of phenyl ring. NMR and single crystal X-ray data

substantiates these observations. Incorporation of suitable donating groups

on phenyl ring of an arylpolyene scaffold bearing pyridine as an acceptor

reveals remarkable fluorescence properties with strong bathochromic

emission shifts. Methylation of pyridine results in a positively charged

pyridinium ion which enhances the electron withdrawing ability and show

strongly red-shifted emission near ~700nm. Such a strong emission, coupled

with water-solubility can have useful applications as fluorescence probes for

biological media.

Electrical Engineering

Title : Characterizing high-frequency behaviour of transformer by reduced-

order circuit model and assessing the severity of mechanical

deformations

Researcher : Shah, Krupa Rajendra,

Supervisor : Ragavan, K.

Department : Electrical Engineering

Year : 2015

Pages : 122

Call No. : 620 SHA

Acc. No. : T00096

Keywords : high voltage; short-circuit; reduced-order circuit model; estimation of

transformer winding; mechanical deformations; power transformer

Abstract : Stability and reliability of the power system is highly affected by the state of

apparatus connected to it. High voltage power transformer is one of the

crucial elements associated with transmission and distribution of electrical

energy and hence its uninterrupted functioning is of utmost importance.

Abnormal forces generated during short-circuit and transportation would

cause permanent mechanical deformations in transformer. Such incipient

fault grows and eventually would lead to catastrophic failure. Therefore,

identifying mechanical deformation and assessing its severity is paramount

for smooth functioning of transformer and power system. Mechanical

deformation of windings gets reflected as changes in the high-frequency

behaviour of transformer. Hence, characterizing its high-frequency behaviour

is essential. For this purpose, physically realizable ladder circuit

corresponding to the high-frequency behaviour of the transformer winding

can be built. On this line, ladder circuit incorporating electrical and magnetic

couplings has been widely accepted as suitable representation. In order to

develop circuit model, certain terminal quantities are required. In this work,

a generalized procedure is proposed to estimate various quantities such as

effective shunt-capacitance, equivalent inductance and capacitance from the

terminal data. It is found in literature that estimating effective series

capacitance is not straightforward. To this end, an algorithm is presented.

The algorithm is validated considering case studies on circuit model, single-

winding and two-winding transformer. To assess the status of transformer

winding with regard to mechanical deforma-tion, an approach is proposed.

Utilizing the above mentioned terminal quantities and by performing

sequential iterations, high-frequency behaviour is represented by an

equivalent circuit model. The circuit model is synthesized such that its natural

frequencies, terminal inductance and capacitance are nearly same as that

obtained through measurement. This methodology involves comparing the

cir-cuit model corresponding to its present state with that of its counterpart

when it was healthy. The location of deformation is identified by the changed

parameter in the circuit. Further, the amount of change reveals the severity

of introduced deformation. In practice, the transformer has many windings.

In such scenario, extending the proposed approach for fault diagnostics

becomes very challenging. As there is

a need to model the high-frequency behaviour of winding by a ladder circuit,

multiple winding unit corresponds to multiple ladder circuits. All these ladder

circuits are electrically and magnetically coupled. Using such complex multi-

ladder network for the purpose of diagnostics is really cumbersome. To this

end, an approach is presented for simplifying this complex network. In this

work, multi-winding transformer unit is realized by a reduced-order circuit

model, that is, single ladder circuit. Once such ladder circuit is available, the

same principle of comparing two circuits is followed. The algorithm is

demonstrated with a two-winding transformer unit. Further, a novel method

is proposed to minimize resonance effects in transformer. This method

involves designing transformer winding corresponding to power frequency

excitation. Utilizing such geometrical information, estimation of its constants

such as inductances and capacitances is achieved. Then, these parameters are

utilized for constructing physically realizable ladder circuit model. From the

circuit model, natural frequencies are estimated. If any of the natural

frequencies coincides with the dominant frequency of the incoming surge then

winding geometry is modified. The new set of natural frequencies can be

obtained such that the resonance phenomenon is avoided.

Title : Controls for Moderating Generation-Demand Mismatch in Wind-

Solar-Hydro Energy Conversion Systems

Researcher : Ramprabhakar, J.



Year : 2016

Pages : 93

Call No. : 621.04 RAM

Acc. No. : T00098

Keywords : Wind-solar-hydro energy; Distributed generation (DG); Energy conversion

system; Frequency control; STATCOM; Static compensator

Abstract : Distributed generation (DG) is related with the use of small generating units

installed at locations of load centres. DG can be used in an isolated way,

supplying consumers’ local demand, or integrated into grid supplying the

energy to the remainder of the electric power

system. DG technologies can run on renewable energy resources, and its

capacity ranges in size from less than kilowatt to tens of megawatts. DG has

attracted a lot of attention world wide, since it decreases the dependency on

fossil fuel and also in reducing the emission of the greenhouse gases. The

power derived from renewable sources such as wind flows and solar irradiance

are unreliable owing to its seasonal and diurnal variations. To surmount the

said defiance, power electronics and controls are used to coordinate the

renewable power systems. This thesis is focused on modelling, control and

power management of electronically interfaced distributed energy resources.

To this end, mathematical model of each energy conversion system is

developed and they are interfaced through power converters. For this

integrated hybrid system, frequency control, voltage amplitude regulation

and moderation of generation-demand (G-D) mismatch are the primary

control requirements. In order to achieve this control schemes are proposed

for the power electronic converters to regulate the power flow under balanced

and unbalanced load conditions.

For the hybrid scheme to operate effectively in integrated mode, effective

control has to be done in order to meet the changing demand, despite

variation in generation. An objective function is formulated to forecast the

power harvested from the renewable sources. Moreover, the objective

function also estimates the energy reserve available to meet the demand. In

order to maintain the dc-link voltage constant, despite variations in G-D gap,

an adaptive control technique is devised. In this technique, dc-link voltage is

shown to be maintained by adaptive gain control that relates dc-link voltage

to the power output of battery system. Further, the proposed objective

function is such that, it can quantify the uncertainty with renewable

generation forecast and battery power output. Further, this research work is

extended to provide reactive power support by connecting static compensator

(STATCOM) at point of common coupling. With this, it is possible to provide

control measures to protect the system under emergency situations like

sudden rise in demand. The STATCOM control is modified to maintain

balance currents in the converter, despite unbalanced load conditions.

Title : Grid converter synchronization techniques for distributed generation

systems

Researcher : Chandrasekaran, S.

Supervisor : K, Ragavan


Year : 2015

Pages : 88

Call No. : 621.3 CHA

Acc. No. : T00059

Keywords : Synchronization; Grid variables; Shunt active power filter;Discrete Fourier

transform; Power system; DG units

Abstract : The exponential growth of renewable energy resources based distributed

generation (DG) systems is due to the ever increasing power demand and

environmental concerns. The DGs are integrated to the grid through power

electronic converters and they contribute to the enhancement of reliability

and efficiency of power system. However, due to the increased penetration,

DGs cause concern about stability due to their interaction with the grid.

Hence, grid codes stipulate that DGs must have fault ridethrough capability

and specify the range of values of voltage and frequency for which they should

remain connected to the grid. Therefore,

fast and accurate estimation of grid variables such as amplitude, phase and fre

quency is essential. Further, these information are vital in the reference

current generation for converters. In this regard, this thesis focuses on

developing grid variables monitoring scheme suitable for normal and

abnormal grid conditions.

This thesis presents sliding DFT prefiltered synchronous reference frame

phase locked loop (PLL) for tracking the grid voltage attributes. With this

prefilter, dc offset and harmonics present in the input are blocked from

entering PLL. Further, the input voltage is amplitude normalized. The

proposed scheme is suitable for singlephase as well as threephase applications.

In the singlephase scheme, slid ing DFT acts as prefilter and orthogonal

signal generator. In case of threephase scheme, with the help of sliding DFT,

the instantaneous symmetrical components (ISC) method succeeds in

identifying the fundamental positivesequence (FPS)

component. With this capability, even during severe disturbance and

unbalance, rapid and precise tracking of utility variables is achieved.

Synchronous sampling is essential for the deployment of sliding DFT.

However, when the grid frequency deviates from the nominal value, sampling

becomes asynchronous. To address this problem, two variants of this scheme

are proposed.

HSS (Cognitive Science)

Title : Role of attentional scope on altruistic decisions

Researcher : Mukherjee, Sumitava

Supervisor : Manjaly, Jaison A.

Department : HSS (Cognitive Science)

Year : 2013

Pages : 118

Call No. : 153 MUK

Acc. No. : T00048

Keywords : In

ation; Elko; NSS; Cosmological perturbation theory; Dark energy; Cosmic

coincidence problem

Abstract : Understanding the cognitive mechanisms involved in altruistic decisions

could enable us to better comprehend complex social interactions and also

help us achieve a larger social gain. I sought to identify domain-generic

mechanisms that could underlie charitable donation and investigated how

content-free processing style linked with scope of attention influence

altruistic decision. Attention is an important cognitive process that can

influence a variety of behavior including prosociality. Most previous studies

are based on effects of the presence (or lack) of attention using the framework

of attention as a resource. Comparatively, there has been hardly any work on

how differences in scope of attention could influence altruistic decisions. The

overall hypothesis of the thesis was that since global processing is linked with

eager approach orientations, love, compassions, an interdependent-self model

and widening of one’s thought-action repertoire; it should increase altruistic

behavior. Five studies were performed to investigate how attentional scope

influence altruistic decisions. Study 1 and 2 experimentally manipulated

scope of attention and found that priming a broad scope of attention using a

global processing style increases propensity to donate money for poor

children. Study 3 found that global processing leads to increased allocation

towards charities whose appeal is framed in an approach orientation compared

to appeals framed in an avoidance orientation. In study 4, even when socio-

economical backgrounds were matched, global processing lead to more

donations in an anonymous economic game among students. Study 5, showed

that real-world motivational states like love and hunger which is linked with

global and local processing respectively, influence donations in predictable

ways. This thesis conclusively shows that attentional mechanisms play

important role in decision making. Specifically, it adds to the literature on

attentional scope and perceptual processing styles by showing for the first

time, global-local processing styles can influence altruistic decisions. One of

the important contributions of this thesis is that some seemingly unrelated

previous studies on donations and pro-social behavior can possible by seen in

light of the domain-generic global-local processing framework. After

discussing some limitations of these studies, I conclude with a model of

attentinal broadening and highlight possible applications to other fields.

Title : Role of sensory prediction on perceptual and motor mechanisms

Researcher : Kumar, Neeraj

Supervisor : Manjaly, Jaison A.

Department : HSS (Cognitive Science)

Year : 2014

Pages : 210

Call No. : 153 KUM

Acc. No. : T00049

Keywords : Predication of sensory; motor mechanisms; human existence; limb state

estimation; somatosensory mechanisms;

Abstract : The ability to interact with the environment through action is an essential

aspect of human existence. Predication of sensory action outcome allows us

to optimally influence and manipulate the environment for a meaningful

interaction. Four studies were performed to investigate the role of

predication on limb state estimation, sense of agency, attentional selection,

and perceptual decision mechanisms. In study 1, prediction was updated by

both relevant and irrelevant predication error in a visuomotor adaptation

tack. Results showed the altered perceptual estimate of limb position after

adaptation. Results suggest that somatosensory mechanisms use the

predictions about the sensory consequences of movement commands and do

not rely solely on the information provided by the sensory systems. Study 2

manipulated the feedback about the action performed and found that error

monitoring mechanisms evoked through feedback recalibrate the prediction

in real time and optimize the sense of self- agency. Study 3 investigated the

role of predication on attentional selection mechanisms by employing

irrelevant feature singleton paradigm of visual search. Feature singleton was

either presented as results of an action or it appeared automatically. Results

suggest that singleton captures attention when preceded by action. It

suggests that predication could be considered as a third factor apart from top-

down goals and bottom-up features of the stimulus which determines how

attention is allocated to the environment. Study 4 investigated how updating

sensory predictions through motor adaptation influences perceptual

processing and subsequent decisions based on the outcome of those

perceptual processes in a visual search task. Results demonstrate the strong

influence of adaptation and updating of predictive mechanism that adaptation

entails on perception and decisions based on perceptual processing.

Perceptual decisions can be clearly modified by manipulating the relationship

between movement commands and their sensory consequences, and the

degree of the modification may depend on how strongly the adapted state is

reinforced. This thesis provides a holistic perspective about the contribution

of prediction in various cognitive processes. It also provides conclusive and

novel evidence to supports the hypothesis that cognition emerges out of out

interaction with the world.

Humanities & Social Sciences

Title : Gender Politics and Indian Children’s Literature: A Comparative

Analysis of Adventure Fiction in English and Gujarati

Researcher : Pundrik, Vyas Diti

Supervisor : Lahiri, Sharmita and Mathur, Suchitra

Department : Humanities & Social Sciences

Year : 2015

Pages : 276

Call No. : 890.0954 VYA

Acc. No. : T00094

Keywords : Politics; India; Gujarat; Children's; Fiction; English; Gujarati

Abstract : Gender emerges as a recurrent theme in debates about contesting merits of

Indian Writing in English (IWE) and regional language literature (RLL)

becoming a pivot that splits them along “progressive” versus “traditional”,

“parochial” versus “cosmopolitan” binaries. This thesis investigates if this

literary split is mirrored in Indian children’s literature through a comparative

study of Indian children’s literature in English (ICLE) and children’s

literature in Gujarati (CLG). It uses materialist feminist approach to unmask

the operations of power, focuses on literature post critically hailed watershed

of 1990 and looks at the dominant genre of adventure. Several locations where

such gender politics are seen to be operational such as representation of

femininity and masculinity, and the narrative structure of adventure genre are

examined as is the intersection of gender with hegemonic structures such as

caste, class and community.

The conclusions reveal that hegemonic conception of gender invoked through

“parochial” and “traditional”, and its non-hegemonic aspect referred to in

“progressive” and “cosmopolitan” are present in both ICLE and CLG, while

differences emerge in how hegemonic norms are upheld or interrogated.

Texts adhering to the wide spectrum of hegemonic masculinity defined by

R.W. Connell exist in both ICLE and CLG alongside those that challenge

these definitions using strategies from inversion to reconfiguration. Similarly,

texts that embed hegemonic notions of femininity in both ICLE and CLG

stand side by side those that attempt feminist revision using strategies from

gender role reversal to gender-mix. Hegemonically gendered ICLE and CLG

texts endorsing patriarchal conventions and definitions of the quest plot and

resorting to patriarchal structuring, spatial and temporal politics, co-exist

with non-hegemonically gendered ones re-gendering, redefining, reframing

or rupturing these conventions. While these similarities in gender politics

undermine the IWE/RLL split, feminist intersectional analysis of gender

with other parameters, partially reverses its association. Though ICLE and

CLG construct gendered anti-minority community stereotypes and

“savarnize” the women’s question, CLG seems more progressive in

questioning intersectional class and gender hierarchies and projecting

alternative dalit masculinity.

These complex conclusions undermine the literary split between IWE/RLL

and underline the relevance of studying children’s literature through a

dialogue with mainstream criticism.

Physics

Title : Effects of lower atmospheric and solar forcings on daytime upper

atmospheric dynamics

Researcher : Laskar, Fazlul Islam

Supervisor : Pallamraju, Duggirala

Department : Physics

Year : 2014

Pages : 142

Call No. : 539 LAS

Acc. No. : T00054

Keywords : Atmospheric coupling; Dayglow; Ionosphere; Upper atmosphere; Sudden

stratospheric warming; Sun-Earth interaction; Gravity waves; Planetary

waves.

Abstract : The upper atmosphere of the Earth is influenced by incoming solar radiation

(UV, EUV, and X-rays) and by secondary effects like waves from the lower

atmosphere. The EUV radiation is absorbed above about 100 km altitude of

the Earth's surface by atomic and molecular constituents resulting in their

excitation to higher energy states. These excited species while returning to

their respective ground states give rise to radiations, which are called dayglow

(or daytime airglow). Chemically excited atmospheric species can also

contribute to dayglow emissions. The intensity of these dayglow emissions

depends on the number densities of the reactants and on the temperature. The

distribution in densities of the reactants can be affected by the waves, thereby

leading to the variations in the intensities of the dayglow emissions. Thus, the

dayglow measurements provide an effective means to investigate the upper

atmospheric dynamics, which are influenced by both solar flux variations and

lower atmospheric processes.

Solar activity changes due to its internal dynamics giving rise to variations of

different periods ranging from hours to years. The lower atmospheric waves

are excited by topography, convection, etc., and in the presence of stable

atmosphere they can propagate to the upper atmospheric altitudes. In this

study we characterize various types of coupling processes in the atmosphere

and their variations with waves and solar activity. The main data set that has

been used in this work has been retrieved using Multiwavelength Imaging

Spectrograph using Echelle-grating (MISE). MISE is a unique instrument

capable of obtaining daytime sky spectra at high-spectral resolutions over a

large field-of-view. From such spectra of MISE oxygen dayglow emission

intensities at 557.7 nm, 630.0 nm, and 777.4 nm wavelengths have been

obtained. In addition to oxygen dayglow emission intensities, data sets of

ionospheric total electron content (TEC), zonal mean winds and temperatures

from the stratosphere to the lower thermosphere, and the equatorial electrojet

(EEJ) strengths have been used.

In this thesis, it has been shown that the lower atmospheric influence on the

upper atmosphere through waves is affected by solar activity. This is because

the latter is responsible for the alteration of the atmospheric background

conditions on which wave propagation and dissipation depend. From an

investigation of the oscillations of planetary wave regime in dayglow and

other atmospheric parameters at three different levels of solar activity, it has

been shown that the vertical coupling of atmospheres through these waves is

solar activity dependent. It is proposed that: (i) the effect on upper

atmospheric dynamics due to lower atmosphere exists at least until the

average sunspot number (SSN) is 35, (ii) there is a transition from the lower

atmospheric forcing to mixed behavior between average SSNs of 35 to 52, and

(iii) another transition from mixed effects to those of purely solar origin

occurs between SSN values of 52 to 123. Further, in this thesis it has also been

shown that even during high solar activity period if a sudden stratospheric

warming (SSW) event occurs then the vertical coupling is enhanced, as the

SSW related processes provide additional energy to enable this coupling.

A statistical study of gravity waves present in the thermospheric altitudes is

made using the three dayglow emissions and the EEJ strength data obtained

during the years 2011 to 2013. The gravity waves are found to be present in

higher numbers in the thermosphere during higher solar activity of 2013

compared to 2011, which is attributed to a reduction in dissipation in the

lower thermosphere during higher solar activity epoch.

Investigations using long-term data sets of EEJ and TEC revealed that the

vertical coupling during SSW events depends on the strength of the SSW.

Also, the interaction between quasi-16-day planetary waves and semi-diurnal

tides has been found to be very strong for the strong major SSW events. In

an another result, using both ground- and satellite-based optical remote

sensing measurements, a new circulation cell in the mesosphere-

thermosphere system has been shown to exist during SSW events, which has

been alluded to in previous modeling studies.

Title : Finite Temperature Effects in the Condensates of Dilute Atomic Gases

Researcher : Arko Roy

Supervisor : Angom Dilip Kumar Singh


Year : 2015

Pages : 123

Call No. : 530.43 ROY

Acc. No. : T00091

Keywords : Bose Einstein condensation; Finite temperature theory; Evolution of

goldstone; Condensate mixtures; Condensates; Atomic gases; Goldstone

modes; Binary BECs

Abstract : The stationary state solutions and dynamics of Bose-Einstein condensates

(BECs) at T = 0 are well described by the Gross-Pitaevskii (GP) equation.

BECs of dilute atomic gases have been experimentally achieved at ultracold

temperatures of the orders of 10�9 K. To include the effects of finite

temperature on these condensates one needs to generalize the GP equation.

We report here the development of the Hartree-Fock-Bogoliubov theory with

the Popov (HFB-Popov) approximation for trapped twocomponent BECs

(TBECs). It is a gapless theory and satisfies the Hugenholtz-Pines

theorem. The method is particularly well suited to examine the evolution of

the lowlying energy excitation spectra at T = 0 and T 6= 0. Apart from the

two Goldstone modes corresponding to each of the species in quasi-1D TBEC,

we show that the third Goldstone mode, which emerges at phase-separation

due to softening of the Kohn mode, persists to higher interspecies interaction

for density profiles where one component is surrounded on both sides by the

other component. These are termed as sandwich type density profiles. This is

not the case with symmetry-broken density profiles where one species is

entirely to the left and the other is entirely to the right which we refer to as

side-by-side density profiles. However, the third Goldstone mode which

appears at phase-separation gets hardened when the confining potentials have

separated trap centers. This hardening increases with the increase in the

separation of the trap centers in which the TBECs have been confined.

Furthermore, we demonstrate the existence of mode bifurcation near the

critical temperature. We also examine the role of thermal fluctuations in

quasi-1D TBECs of dilute atomic gases. In particular, we use this theory to

probe the impact of non-condensate atoms to the phenomenon of phase-

separation in TBECs. We demonstrate that, in comparison to T = 0, there is

a suppression in the phase-separation of the binary condensates at T 6= 0.

This arises from the interaction of the condensate atoms with the thermal

cloud. We also show that, when T 6= 0 it is possible to distinguish the phase-

separated case from miscible from the trends in the correlation function.

However, this is not the case at T = 0. In a BEC, a soliton enhances the

quantum depletion which is sufficient enough to induce dynamical instability

of the system. For phase-separated TBECs with a dark soliton in one of the

components, two additional Goldstone modes emerge in the excitation

spectrum. We demonstrate that when the anomalous mode collides with a

higher energy mode it renders the solitonic state oscillatory unstable. We also

report soliton induced change in the topology of the density profiles of the

TBEC at phase-separation. For quasi-2D BECs, at T = 0, we show that with

the transformation of a harmonically to toroidally trapped BECs, the energy

of the Kohn modes gets damped. This is examined for the case when the radial

angular frequencies of the trap are equal. The other instance, when the

condensate is asymmetric, the degeneracy of the modes gets

lifted. The variation in the anisotropy parameter is accompanied by the

damping of the modes, the quasiparticle modes form distinct family of curves;

each member being different from the other by the principal quantum number

n. When T 6= 0, with the production of a toroidally trapped BEC, the maxima

of the thermal density tends to coincide with the maxima of the condensate

density profiles. This is different from the case of a harmonically trapped BEC

in which due to the presence of repulsive interaction between the atoms, the

thermal density gets depleted where the condensate atoms are the highest.

Title : Inflationary scenario with non- standard spinors

Researcher : Basak, Abhishek

Supervisor : Bhatt, Jitesh R.


Year : 2013

Pages : 111

Call No. : 539 BAS

Acc. No. : T00050

Keywords : In

ation; Elko; NSS; Cosmological perturbation theory; Dark energy; Cosmic

coincidence problem

Abstract : Inflationary scenario has been very successful in solving various problems

associated with the standard Big Bang cosmology. But the nature of the field

that drives accelerated expansion (inflaton) is still unknown to us. The

inflationary models with scalar fields, under the slow-roll approximations, are

well studied. In contrast, inflationary scenario with spinor fields have not

attracted much attention. In earlier works the ̀ classical' Dirac spinor field was

studied as a candidate of inflaton. However, there were some issues with

inflationary scenario driven by the Dirac spinor. One of the most important

problem with Dirac spinor is that it produces highly scale dependent power-

spectrum (with spectral index ns 4), which is inconsistent with the CMB

observations.

Recently, one special type of spinor was proposed by Ahluwalia (2005, 2013)

which is an eigenspinor of charge conjugation operator, also known as Elko.

This spinor is called the Non-Standard Spinor (NSS) as it has an unusual

property: (CPT)2 = �I. NSS field is a spin-1/2 field with mass dimension

one, whereas the `classical' Dirac spinor is a spin-1/2 fermion with mass

dimension 3/2 . This new spinor field obeys the Klein-Gordon equation

instead of Dirac equation. NSS can interact only through Higgs and with

gravity, therefore it is dark by nature. Thus it is worth investigating the role

of NSS in the unknown dark sector of the universe like: Dark matter, dark

energy and inflation etc. In this thesis our focus is on the NSS driven

accelerated expansion of the universe.

In the earlier NSS theories there was one major inconsistency -- the equation

of motion of NSS obtained from the energy-momentum tensor did not match

with the equation of motion calculated using the Euler-Lagrange equation.

Recently a consistent theory of NSS was developed which removed this

inconsistency. In this thesis we use a consistent NSS theory to study the first

order cosmological perturbation theory for NSS. The NSS Lagrangian and

the energy-momentum tensor can be expressed as follows:

where and : is the NSS and its dual. The covariant derivatives are defined

as: : � r @ : + : � and r @ � � where, � is the spin connection. In

the expression of energy-momentum tensor the F term, which was absent in

the earlier works, appears because of the variation of � with respect to the

metric (Bohmer et al., 2010). Using a simple ansatz of the perturbed NSS and

its dual, = ' , : = ': where ' is a scalar and is a constant spinor with the

property : = 1, we have calculated omponents of the perturbed

energymomentum tensor. The perturbation theory for NSS becomes like a

scalar field theory. However, calculation of the energy-momentum tensor

shows the presence of additional terms in comparison with the standard

canonical scalar field. We construct the modified Mukhanov-Sasaki equation

for the NSS. Unlike scalar field case, the sound speed square is shown to be c2

s 6= 1 in general. The spectral index for the scalar perturbation is shown to

give a nearly scale invariant powerspectrum which is consistent with the

observation provided that ~ F '2 8M2 pl < 10�4. With this upper bound c2

s 1. Thus in case of first order perturbation theory, NSS becomes

indistinguishable with the canonical scalar field theories.

In this thesis we have also studied the attractor behavior of NSS cosmology.

In inflationary and dark energy theories it is difficult to find exact initial

conditions. Therefore it is important that these theories show the attractor

behavior, which will allow a wide class of solutions with different initial

conditions to have similar asymptotic behaviour. The search for an attractor

in case of NSS was attempted before also (see Wei, 2011). But no stable fixed

points were found in the earlier attempts. In this thesis it is shown that the

NSS equations can give inflationary-attractor which corresponds to 60 e-

foldings. We have also demonstrated, with a new definitions of variables, that

in the presence of barotropic perfect fluid the dynamical equations of the NSS

can have stable fixed points. The stable fixed points can give us late-time

attractor for NSS which can be useful in alleviating the cosmic coincidence

problem. The stable fixed points are achieved by redefining the kinetic and

potential part of NSS.

Title : Spectral and Timing Studies of Accretion Disk in Black Hole Binaries

Researcher : Jassal, Anjali Rao

Supervisor : Vadawale, Santosh. V.


Year : 2015

Pages : 141

Call No. : 621.04 JAS

Acc. No. : T00099

Keywords : accretion; accretion disks; black hole physics; X-rays: binaries, X-rays:

individual (GRS 1915+105, MAXI J1659−152, IGR J17091−3624)

Abstract : Accretion around compact objects is the most efficient way of extracting

energy from material in an accretion disk. Luminous accretion disks around

black holes in mass transferring black hole binaries offer an opportunity to

study accretion processes taking place in the extreme conditions of

temperature and gravitational field. However, these astrophysical sources

cannot be observed with ground based conventional telescopes because they

emit mainly in X-rays. Therefore, data are collected with space borne X-ray

observatories. Spectra, light curves and images extracted from data are used

as probes to understand the radiative processes in accretion disks. Although

a significant understanding of the sources has been developed with the help

of several empirical and theoretical studies, there are several phenomena,

which are not understood. This thesis presents the efforts that have been made

to understand some of these phenomena.

A majority of black hole binaries are transient in nature and they keep on

switching between quiescent and outburst states. It is generally believed that

an accretion disk is truncated far away from the central black hole during

quiescent states. However, the observational evidence for this general picture

is indirect at best. We studied a transient black hole candidate MAXI

J1659−152 during its 2010 outburst, which was detected during very early

stages of the outburst. We investigated the variation of the inner disk radius

with progress of the outburst and found that the disk is truncated at larger

radii in the beginning. A systematic decrease in the inner disk radius was

found as the source transitions towards the soft states. We estimated mass of

the black hole to be 8.1±2.9 M⊙ with the help of normalization of the disk

blackbody component.

A transient black hole candidate IGR J17091−3624 is studied, which behaved

like ‘normal’ black hole binaries except during its latest outburst in 2011. The

source showed properties similar to a unique black hole binary GRS

1915+105, known for exhibiting extreme variability. High mass accretion

rate is believed to give rise to extreme variability, therefore IGR J17091−3624

is expected to be a bright source. However, IGR J17091−3624 is about 20

times fainter as compared to GRS 1915+105. We performed a comparative

study of the two sources by investigating ‘heartbeat’-type variability observed

in their light curves. The light curves were folded and spectra were generated

for the 5 phases of ‘heartbeat’ oscillations. The spectra were fitted

simultaneously by tying the system parameters and leaving the accretion-

process-dependent parameters independently free across the 5 phases. We

found important constraints on mass, distance, inclination

and spin of IGR J17091−3624. It was noticed that the estimated value of spin

is low (a∗ < 0.2) as opposed to the high value of spin for GRS 1915+105. We

suggest that the low spin of the black hole in IGR J17091−3624 can be a

reason behind its faintness as compared to GRS 1915+105 instead of showing

variability patterns arising from high mass accretion rate.

Black hole binaries are known for showing quasi periodic oscillations (QPOs)

during hard states, which appear as narrow peaks superimposed on the broad

band continuum in power density spectrum. Several studies have shown the

correlation between QPO properties and spectral parameters, indicating a

close link between the two. However, the mechanism behind generation of

QPOs is not well

understood. The thesis presents our attempts to understand the QPO

mechanism by simulating light curves. We studied a NuSTAR observation of

GRS 1915+105, which has a power law dominated spectrum and shows the

presence of reflection component. Since there is only one primary component,

we make a hypothesis that the QPO is generated as a result of oscillation of

some of the spectral

parameters (instead of spectral components) at frequencies close to that of the

QPO. We test the hypothesis by finding whether the simulated results explain

the observed energy dependence of QPO or not. It was found that the

observed trend of increasing QPO power with energy can be reproduced

qualitatively if the spectral index is varied with the phases of QPO. Variation

of other spectral

parameters does not reproduce the observed energy dependence. The

variation of spectral index is verified by performing phase-resolved

spectroscopy for the phases of QPO. The results clearly show the variation of

spectral index with the phases of QPO. The finding of variation of spectral

index is an important result and it puts significant constraints on the models

explaining modulation mechanism for QPOs.

Title : Stable water isotopologues in the Indian summer monsoon rainfall

Researcher : M, Midhun

Supervisor : Ramesh, R.


Year : 2015

Pages : 111

Call No. : 551.90954 MMI

Acc. No. : T00089

Keywords : Indian Summer Monsoon; Stable water isotopologues; Amount effect; isotope

enabled General Circulation Models; Paleomonsoon

Abstract : Stable oxygen isotope ratios ( 18O) of tree cellulose and speleothem carbonate

are useful proxies for past monsoon rain in many tropical regions, as in such

region a decrease in rain 18O accompanies an increase in rainfall on a monthly

time scale. This amount e

ect varies spatially; therefore a local calibration, with actual measurements of

rain amount and its 18O is required. Such observations, however, are quite

limited in space and time. This thesis is aimed to improve the understanding

of factors that control the 18O of Indian monsoon rainfall. For the

present study water vapor samples were collected from the marine

atmosphere over the Bay of Bengal (BoB) and rainfall sampled from Central

and Northern India. The multiple simulations from isotope enabled General

Circulation Models (GCM) are also used to understand the variability of the

18O of the Indian Summer Monsoon (ISM) rainfall on daily to interannual

time scales.

Measurements of stable isotopic compositions ( 18O and D) of water vapor

collected from the BoB helps characterize both ISM vapor and North East

Monsoon (NEM) vapor. This study shows that vapor 18O is higher during

ISM compared to NEM with higher d-excess during NEM. This seasonal di

erence is possibly due to the seasonality in sea surface conditions, change in

circulation pattern and changes in the type of rain forming systems (monsoon

depression during ISM vs. tropical cyclones during NEM). The stable

isotopic composition of water vapor estimated using Craig and Gordon model

with the closure assumption (i.e., evaporation from the BoB is the only source

of vapor) matches well with the measured values during non rainy days of

ISM, whereas, it shows a large deviation from the model estimate during

NEM season. The deviation from model estimate is negatively correlated with

the rainfall along parcel trajectory (upstream rainfall) during both the

seasons. The convective downdraft associated with tropical cyclones during

NEM also plays major role in the lowering of vapor 18O

During ISM 2013, rain water samples were collected on a daily basis from six

dierent cities (Ahmedabad, Bhopal, New Delhi, Kanpur, Varanasi and

Dhanbad) spread over central and northern India and stable isotopic analyses

were carried out. A weak amount feect (negative correlation between local

rain and its 18O) is observed at ve out of the six stations, which explains 7-

22 % of intraseasonal variation of 18O of rain. The nudged simulations from

an isotopeenabled General Circulation Model (IsoGSM) is compared with the

observations. Though the model has some limitation in simulating the

accurate spatio-temporal pattern of rainfall, the model simulated rain 18O is

in good agreement with the observations. This study suggests strong control

of moisture transport pathways on daily rain 18O at Ahmedabad, Bhopal and

New Delhi. At New Delhi this feect is observed on intraseasonal to

interannual timescales.

Many isotope enabled General Circulation Models (GCM) are used to aid the

interpretation of rainfall-18O based proxies; nevertheless, all such simulations

taken together remained to be evaluated against observations over the Indian

Summer Monsoon (ISM) region. This study also examine ten such GCM

simulations archived by the Stable Water Isotope INtercomparison Group,

phase 2 (SWING2). The spatial patterns of simulated ISM rainfall and its

18O are in good agreement with the limited observations available.

Simulations nudged with observed wind elds show better skill in reproducing

the observed spatio-temporal pattern of rainfall and its 18O. A large

discrepancy is observed in the magnitude of the simulated amount eect over

the Indian subcontinent between the models and observations, probably

because models simulate the spatial distribution of monsoon precipitation di

erently. Nudged simulations show that interannual variability of rainfall 18O

at proxy sites are controlled by either regional (rather than local) rainfall or

upstream rain out. Interannual variability of rainfall 18O over the East Asian

region is well correlated with El Ni~no Southern Oscillation (ENSO), while

it is only weakly correlated over the Indian sub-continent.

Title : Vortices of light and their interaction with matter

Researcher : Prabhakar, Shashi

Supervisor : Singh, R. P.


Year : 2014

Pages : 120

Call No. : 535 PRA

Acc. No. : T00057

Keywords : Singular optics; Optical vortex; Spontaneous parametric downconversion;

entanglement; Wigner distribution function; Bell's inequality; Vortex dipole

annihilation; Bose-Einstein condensates

Abstract : Optical vortices are singularities in the phase distribution of a light field. At

the phase singularity, real and imaginary parts of the field vanish

simultaneously and associated wavefront becomes helical. For an optical

vortex of topological charge l, there are l number of helical windings in a

given wavelength of light and it carries an orbital angular momentum of l~

per photon. This dissertation concerns with the study of interaction of optical

vortices with matter namely nonlinear optical crystal -Barium Borate (BBO)

and Bose-Einstein condensate.

A new method to determine the order of optical vortex from just the intensity

distribution of a vortex has been discussed. We show that the number of dark

rings in the Fourier transform (FT) of the intensity can provide us the order.

To magnify the effect of FT, we have used the orthogonality of Laguerre

polynomials.

We have studied the interaction of optical vortices with BBO crystal. The

spatial-distribution of degenerate spontaneous parametric down-converted

(SPDC) photon pairs produced by pumping type-I BBO crystal with optical

vortices has been discussed. For a Gaussian pump beam, we observe a linear

increase in thickness of the SPDC ring with pump size. On the other hand,

the SPDC ring due to optical vortex forms two concentric bright rings with

an intensity minimum in the middle. We also observe that if the beam size is

lower than a particular value for a given topological charge l of the vortex,

then there will be no change in full-width at half maximum of the rings formed

by down-converted photons.

We have experimentally varied the quantum inspired optical entanglement

for classical optical vortex beams. The extent of violation of Bell's inequality

or continuous variables written in terms of the WDF increases with the

increase in their topological charge. To obtain this, we have used the FT of

two-point correlation function that provides us the WDF of such beams.

Quantum elliptic vortex (QEV) is generated by coupling two squeezed

vacuum modes with a beam splitter (BS). The Wigner distribution function

(WDF) has been used to study the properties of this quantum state. We also

study how this coupling could be used to generate controlled entanglement

for the application towards quantum computation and quantum information.

We observe a critical point above which the increase in vortices decreases the

entanglement.

We have also studied the annihilation of vortex dipoles in Bose-Einstein

condensates. To analyze this, we consider a model system where the

vortexantivortex pair and gray soliton generated by annihilation of vortex

dipoles are static and the system could be studied within Thomas-Fermi (TF)

approximation. It is observed that the vortex dipole annihilation is critically

dependent on the initial conditions for their nucleation. Noise, thermal

actuations and dissipation destroy the superflow reflection symmetry around

the vortex and antivortex pair. It is note worthy that some of our theoretical

results have already been verified experimentally.

M. Tech. & M. Sc


(Abstract)

Chemical Engineering

Title : Morphology and optical properties of nanoparticle thin films fabricated

by spread coating

Researcher : Singh, Amit

Supervisor : Thareja, Prachi


Year : 2013

Pages : 55

Call No. : 667.9 SIN

Acc. No. : T00001

Keywords : Morphology and Optical Properties; Nanoparticle Research; Films

Fabricated

Abstract : Thin films are deposited on substrates such as glass slides, silicon wafers,

mica etc with the help of an in house designed Spread Coating Device. Many

particle types such as titanium, silica thin films can be deposited by this device

and the morphology is based on the principle of Convective Deposition

Assembly. The device consists of syringe pump and two glass side holders,

one is inclined at an angle of 40 0 and the other is moving at a user defined

velocity. Different volume fractions of solutions varying from 0.01-0.4 are

prepared suing TiO 2 -960 (3.9 g/cm3) at different velocities from 1 um/sec

to 300 um/sec at room temperature. Thickness, assembly of particles,

roughness and optical properties are measure using SEM, AFM and UV-VIS

spectroscopy. Our experiments show that as the spreading velocity is

increased the films become progressively more uniform. Concomitantly,

the transmittance of the films decreases. The method provides a versatile

way to fabricate thin films with a variety of microstructures with different

properties.

Title : Design of an evaporator for vaporization of glass forming silica

precursor

Researcher : Jadhav, Deepak Babasaheb

Supervisor : Ghoroi, Chinmay


Year : 2013

Pages : 85

Call No. : 666.1 JAD

Acc. No. : T00002

Keywords : Glass Forming; OMCTS; Design of Evaporator

Abstract : Use of silicon tetrachloride (SiCl4) for high purity glass forming silica is very

convenient due it its high vapor pressure. However, in presence of oxy-

hydrogen flame, it forms hydrochloric acid (HCl) which creates

environmental hazard. In contrast, halogen free organometallic precursor

such as Octamethylcyclotetrasiloxane (OMCTS) is a promising alternative.

However, evaporation process of OMCTS is only available the patent

literature with considerable gaps in the scientific understanding in open

literature. In this work, property of OMCTS is studied and analyzed the

different patented designs of Corning Inc. A packed bed evaporator is

designed and fabricated. Different experiments were conducted and tested for

performance of the designed evaporator. The designed evaporator can

generate very highly pure OMCTS vapor required for high purity silica glass.

Unlike previous observations mentioned in the available patent literature,

there was no high molecular specie was observed in the residue of the

designed evaporator.

Title : Colloidal particles self-assembly in liquid crystals

Researcher : Gite, HemantBapurao



Year : 2013

Pages : 52

Call No. : 660.2 GIT

Acc. No. : T00003

Keywords : Liquid Crystals; Colloidal Crystals; Self-assembly; Metal-containing liquid

crystals; Crystal devices; liquid crystal displays

Abstract : Liquid crystals, being anisotropic, act as tunable solvent for the dispersion of

colloidal particles. They also have shown to provide very good support for

the self-assembly of particles into well- organized structures. We

experimentally study the behavior of colloidal particles dispersed in liquid

crystal medium. We have successfully prepared, nematic and hexagonal,

lyotropic liquid crystalline phases. When dispersed into such a solvent,

colloidal particles aggregate to form structures such as chains, clusters,

strands, and the network of particles. Formation of these structures is driven

by interaction arising from the orientation elasticity of the solvent. We used

spherical Polystyrene (PS), Titanium Dioxide (TiO2), Zinc Oxide (ZnO),

Silica (SiO2) and anisotropic Iron Oxides (FexOx) particles to study their

behavior in liquid crystal medium.

We have studied the effect of particle concentration, size and shape on the

self-assembly process. The type of liquid crystal phase and the shape of

nematic liquid crystals are also shown to control the interaction between

particles. Particles with size greater than1μm form small chains and cluster

like structures in nematic phase while smaller particles do not show any

structure formation in this system. In hexagonal phase particles with size less

than 1μm shows network and strand like structures formation while larger

particles do not show such structures. Effect of cooling rate on network

formation was studied. We have also prepared free standing microporous

structure of SiO2 nanoparticles by templating of hexagonal domain.

Title : Modeling of microbubble dissolution in aqueous medium

Researcher : Joshi, Jignesh Rajendrakumar

Supervisor : Dalvi, Sameer V.


Year : 2013

Pages : 157

Call No. : 660.2 JOS

Acc. No. : T00004

Keywords : Microbubbles; Ultra sound contrast agent; drug delivery vehicles;

dissolution; stability; Aqueous

Abstract : Aqueous suspensions of microbubbles find use in various biomedical and

pharmaceutical applications. Microbubbles of size from 1-10 μm, comprise

of a gas core and a shell made of protein, SDS or polymeric material. Most of

the biomedical applications involve intravenous administrations of

microbubbles. Once administered in body, microbubbles start dissolving in

the body media. The effectiveness of these microbubbles depends on their

circulation time in blood. The circulation time (or persistence time) of these

microbubbles largely depends upon the kinetics of their dissolution in body

media. It is therefore necessary to know/predict the time for which the

microbubbles made from a particular formulation will circulate in blood.

Accordingly, the objectives of this work were to model microbubble

dissolution and predict dissolution time.

There are several models available in the literature aimed at attempting the

modeling of microbubble dissolution. However, it was found that, the

existing models do not take into account either the shell elasticity or the

variation in surface tension with change in microbubble size. In this work,

attempt has been made to account for these factors which may affect

microbubble dissolution process greatly.

The model for microbubble dissolution in an aqueous medium saturated with

gas used to make microbubble has been developed. The values of shell

resistance, elasticity and initial surface tension have been regressed by

comparing model with the experimental data available I literature. It is found

that, the shell resistance and elasticity of shell increases with number of

carbon atom in lipids, thus dissolution time of the microbubble increases with

number of carbon atoms in lipids. The dissolution time also increases with

level of saturation and initial radius of the microbubble. As the Ostwald

coefficient decreases, it is also observed that the dissolution time increases.

The life time of gas with lower Ostwald coefficient microbubble is higher.

The degree of variations in shell resistance and surface tension also increases

with number of carbon atom in lipid. However, based on the regressed shell

properties, SDS can be considered as inelastic material as the variation in

surface tension and shell resistance is negligible.

The model for dissolution of microbubble in multi gas environment in water

and in blood has also been developed. Two way diffusion of core gas to the

bulk and the diffusion of air dissolved in the bulk to the gas core have been

considered. The growth in microbubble was observed during its dissolution

due to higher influx of gases dissolved in the aqueous medium than outflux

of gas used to make microbubble. The shell resistance of gases and surface

tension of the microbubble first decreases and then increases. The dissolution

time increases with number of carbon atom in a lipid molecule, initial radius

and level of saturation of the aqueous medium.

Title : Protein-polysaccharide nano-complexes at air water interface

Researcher : Mukherjee, Satyajit



Year : 2013

Pages : 63

Call No. : 660.634 MUK

Acc. No. : T00006

Keywords : Polysaccharide synthesis; Airwater Interface; Nano-Complexes; Protein

interactions

Abstract : Complexation between bovine serum albumin (BSA) and citrus peel pectin

(CPP) was studied by changing pHs and mass ratios with turbidity, dynamic

light scattering, centrifugation and viscosity measurements. Interfacial

behavior at specific pHs and mixing ratios were also carried out by individual

measurements using bubble tensiometer and wilhelmy plate technique. We

investigate comparative long term stability of foam in protein solution and in

a mixed protein (BSA) - polysaccharide (CPP) system. The foam stability is

improved for samples containing soluble complexes which are almost at pH

around isoelectric point of BSA. Initial foam formation solely depends on free

protein content in bulk, and soluble complexes slow down the drainage rate

by their presence at air/water interface, which finally results in the

stabilization of foam. Atomic force microscopic image analysis shows how

this interaction between BSA and CPP leads to change in morphology with

size and shape by forming complexes. These findings have significant value

for application of protein- polysaccharide complex in foam stabilization which

is useful in different engineering applications such as food, pharmaceutical

industries, and cosmetics.

Title : Computational assessment of air pollution dispersion in urban centers

Researcher : Kar, Sayan

Supervisor : Damodaran, Murali


Year : 2013

Pages : 63

Call No. : 628.530151 KAR

Acc. No. : T00007

Keywords : Air pollution dispersion; advection-diffusion equation; Gaussian plume

model; branched Atmospheric Trajectory model; suspended particular matter

Abstract : For air quality modeling, the Gaussian plume model has been extensively

used to analytically solve the steady and unsteady transport equations

including the effects of particle deposition and settling. Along with the

standard analytical solution of the Gaussian plume model for modeling air

pollution dispersion in the atmosphere this work explores the adaptation of a

Lagrangian Branched Atmospheric Trajectory approach for computing

ground level concentrations of PM10 (suspended Particulate Matter of

aerodynamic diameter of less than10 micro meter), PM2.5 emitted from

different air pollution sources in and around the city of Ahmedabad, India.

With a transport time step of 6 hrs, the model includes necessary

meteorological data which couple with multi-pollutant emission grid. The

results obtained from the model are found to be very close to the measured

data (2009-2011) from Gujarat Pollution Control Board.

Title : Experimental study of Bechamp process for nitrobenzene reduction to

aniline

Researcher : Singh, Umesh

Supervisor : Padhiyar, Nitin


Year : 2013

Pages : 48


Acc. No. : T00009

Keywords : Kinetics; Bechamp Process; nitrobenzene reduction; aniline production; rpm

effect on kinetics; Frossling correlation

Abstract : Bechamp process is a well-known process for the reduction of aromatic nitro

compounds using zero valent iron powder in acidic conditions. The Bechamp

reaction is a multiphase reaction with gas, liquid and solid phases. The

complex reaction mechanism contains series and parallel reactions

resulting into by products and side products apart from the amine product.

Overall reduction of nitrobenzene to aniline is a process of three steps in

series, namely adsorption of nitrobenzene on the iron surface, surface reaction

of nitrobenzene to aniline and desorption of the product from the iron surface.

In the literature it is suggested that the adsorption step is the rate limiting

step for nitro aromatic reduction. Nitrobenzene is a carcinogenic pollutant

and is used in dye, agrochemicals and rubber industries. It is reported in

literature that nitrobenzene is dangerous even at lower concentrations (ppm)

and it is non-biodegradable in nature. Reduction of nitrobenzene to aniline

by Bechamp process is carried out in a 500 ml batch reactor in this work. Gas

Chromatograph (GC) is used for the sample analysis. A GC method has been

developed with toluene as the solvent for determining the compositions of

various reaction components.

In our literature study we found that using Bechamp process, nitrobenzene

reduction was studied at ambient temperature and at lower rpm (up to 50).

The effect of temperature on the Bechamp reduction of nitrobenzene was

absent. Also at higher concentrations of nitrobenzene the study was not

available. In this work we filled this gap by studying the Bechamp reduction

of nitrobenzene at various temperatures (30 oC to 100 oC) and higher rpm

(up to 600). We also present the effect of rpm on rate constant and model this

relation of mass transfer constant and rpm by Frossling correlation.

Finally, we have extended the work of reduction of nitrobenzene in a batch

reactor work to the industrial semi-batch system with gradual addition of Fe.

Based on these results, a reaction mechanism of the reduction of nitrobenzene

is suggested in this work.

Title : Experimental study of Bechamp process for p-nitrotoluene reduction to

p-toluidine

Researcher : Popat, Vivek Rasikbhai



Year : 2013

Pages : 45

Call No. : 660.28 POP

Acc. No. : T00010

Keywords : Kinetics; Bechamp Process; p-nitrotoluene reduction; p-toluidine production;

rpm effect on kinetics; Frossling correlation.

Abstract : Bechamp process is a well-known process for the reduction of aromatic nitro

compound using zero valent iron powder in acidic conditions. The Bechamp

reaction is a multiphase reaction with gas, liquid and solid phases. The

complex reaction mechanism contains series and parallel reactions resulting

into by products and side products apart from the amine product. Overall

reduction of p-nitro toluene (PNT) to p-toluidine (PT) is a process of three

steps in series, namely adsorption of PNT on the iron surface, surface reaction

of PNT to PT and desorption of the product from the iron surface. In the

literature it is suggested that the adsorption step is the rate limiting step for

nitro aromatic reduction.

Reduction of PNT to PT by Bechamp process is carried out in a 500 ml batch

reactor in this work. Gas Chromatograph (GC) is used for the sample

analysis. A GC method has been developed with toluene as the solvent for

determining the compositions of various reaction components. In this work,

we have carried out experiments to find out the limiting step for PNT

reduction. We have considered selectivity of PT as performance criteria in

this study at various operating conditions. We also present the effect of rpm

on rate constant and model this relation of mass transfer constant and rpm

by Frossling correlation. Finally, we have extended the work of reduction of

PNT in a batch reactor work to the industrial semi-batch system with

gradual addition of Fe. Based on these results, a reaction mechanism of the

reduction of PNT is suggested in this work.

Title : Numerical study of thermophoretic deposition of nano-silica using

outside vapor depositon

Researcher : Shukla, Upendra Kumar



Year : 2013

Pages : 68

Call No. : 660 SHU

Acc. No. : T00047

Keywords : Outside vapor deposition, optical fiber, thermometric force, deposition

efficiency

Abstract : There are many available processes for optical fiber manufacturing like

modified chemical vapor deposition, vapor axial deposition, and outside vapor

deposition. The most popular method for optical fiber manufacturing on

commercial scale is Outside Vapor Deposition (OVD). Owing to its

fundamental importance, several people have studied (both experimental

observation and numerical study) the effect of process parameters on optical

fiber manufacturing. But all the numerical works available on this topic has

been done in the very small range of process parameter and most of which

are related to two dimensional approximation of the process. Whereas the

industrial range of process parameters are much larger and the actual process

is three dimensional. The objective of the present work is to fill this gap of

knowledge in the literature. The study has been carried out by using

commercial software, ANSYS Fluent which is based on finite volume

discretization of governing equation for flow problems. The simple scheme

has been used for pressure velocity coupling. A second order upwind scheme

is used to discretize the convective terms in momentum, energy, and species

balance equation. The simulation was carried out both in three-dimensional

(3-D) and two-dimensional (2-D) geometry. While 3-D simulation was

performed using steady state, quasi-steady state and unsteady state model, 2-

D simulation was per-formed only for steady state model. The effect of

different parameters such as burner to target distance, target surface

temperature, burner speed, and target diameter on efficiency of deposition

has been studied in this work in the large range of parameter space. The

present solution methodology is consistent with prior publications in the

field, and has been validated with the previous published experimental results

available in literature. It is shown that as the traversing burner speed and

diameter of the target is increased the efficiency of deposition increases due

to increase in thermophoretic force. As the surface temperature increases the

deposition efficiency decreases due to decrease in thermophoretic force. As

the burner to target distance increases, the deposition efficiency first

increases and then remains constant for some interval before decreasing it

rapidly on further increasing the distance between burner and target.

Title : Hydrogen Production Via Catalytic Partial Oxidation Of Methane On

Lanthanum Oxide and Nickel-Lanthanum Oxide Catalysts

Researcher : Menon, R. Aparna

Supervisor : Bhargav, Atul

& Sharma, Sudhanshu


Year : 2014

Pages : 47

Call No. : 660.28443 MEN

Acc. No. : T00013

Keywords : Hydrogen, Nickel, Lanthanum oxide, Methane, Partial oxidation

Abstract : Lanthanum oxide (La2O3) has been of interest as a catalyst due to its lattice

Oxygen content and relatively low cost. However, it has been known to

promote complete oxidation, rendering it unusable for Hydrogen production

through the catalytic partial oxidation (CPO) of methane. Although some

previous studies have been carried out CPO of methane on La2O3, a detailed

analysis of the promotion of complete combustion even in highly reducing

atmospheres has not been fully documented.It was observed that when 5 wt%

of Nickel was loaded on La2O3 catalyst (Ni/ La2O3), the Hydrogen

selectivity increased to almost 8 times. In this paper, we report coking studies

during long term tests on both La2O3 and Ni/ La2O3 catalysts. La2O3,

prepared by solution combustion method and Ni/La2O3, prepared by

chemical reduction method, were used in granule form and were packed

inside a quartz tube. Nitrogen was used as the carrier gas for methane and

Oxygen. Operating conditions such as temperature, residence time and O/C

ratio were first optimized so as to get maximum Hydrogen yield. The CPO

reaction was carried out in a temperature range of 200-750°C. Results

indicate that both methane and Oxygen conversions increase with

temperature. An optimum in methane conversion was observed with

residence time, indicating a complex interaction between lattice Oxygen and

coke formation. The decrease in conversion was thought to be because of coke

deposition on the catalyst which has the capability of deactivating the

catalytic activity. A long term durability test for 160 h was done for the

reaction and amount of carbon deposited was quantified by conducting TGA

analysis. The nature of the coke deposited was studied using FTIR and SEM.

These results are part of a larger effort aimed at understanding the catalysis

of La2O3 and Ni/La2O3 systems.

Title : Colloidal Rhombohedral Particles in Hexagonal Liquid crystal: -

Rheology and Microstructure

Researcher : Mishra, Nishi S.

Supervisor : Theraja, Prachi


Year : 2014

Pages : 76

Call No. : 660.2 MIS

Acc. No. : T00014

Keywords : Liquid crystal, Rheology, Tetraethyl orthosilicate

Abstract : Liquid crystals are a state of matter between solid and liquid which act as

tunable solvents for particles self-assembly. These self-assembled structures

can have unique mechanical, optical, electrical and magnetic properties [1,7,

17]. We report the self-assembly of 104 nm Rhombohedral Fe2O3 (iron

oxide) particles in hexagonal phase of lyotropic liquid crystal. Visually, the

sample is a low viscosity liquid above TH and turns into a soft solid as the

temperature is lowered. This is also manifested in the rheological properties

of this material where the storage modulus (G’) shows several orders of

magnitude increase at the isotropic-hexagonal transition temperature and

almost plateaus as the temperature is further lowered. Rheological

measurements show that the storage modulus of the material depends on two

factors: 1) Particle loading 2) The rate at which the sample is cooled. As

observed for cooling rates of 0.5°C/min iv and 1°C/min, G’ increases with an

increase in particle loading up to 1.5wt% however, such monotonic increase

with cooling rate is not observed as the particle loading is varied from 2.5-

10wt%. However when cooled at 2°C/min, the increase in modulus with

particle loading is pronounced at higher particle loading. Interestingly, the

modulus of the particle free sample shows hardly any effect of cooling rate.

The rheological data suggest that the final microstructure and mechanical

properties are dictated by interplay between the rate at which the hexagonal

domains nucleate and how fast the particles are swept by these domains to

form a compact particle layer at the hexagonal liquid crystal and isotropic

fluid interface. The process has been observed under polarised microscopy for

lower particle loadings. The packing of the particles is very much dependent

on the cooling rate as well as particle fraction. Therefore, both particle

loading and cooling rate affect the mechanical properties of final structure.

We have synthesized silica nano-rods with different total volume of reactants

to see its effect on size of rods and also the effect of Tetraethyl orthosilicate

(TEOS) [26]. Increase in the total volume of reactant led to decrease in the

size of rods with lesser effect on diameter, while the variation in TEOS

concentration showed similar effect but with marginal effect on diameter.

Title : Model Predictive Control Strategy for Optimizing Biological Nitrogen

Removal (BNR) Processes Accounting for Greenhouse Gas Emissions

Researcher : Behera, Chitta Ranjan

Supervisor : Srinivasan, Babji


Year : 2014

Pages : 29

Call No. : 628.357 BEH

Acc. No. : T00015

Keywords : Ammonia oxidizing bacteria, Biological Nitrogen Removal (BNR), Gas,

Greenhouse

Abstract : Biological Nitrogen Removal (BNR) process comprises sequential oxidation

of ammonia to nitrate and subsequent reduction of nitrate to nitrogen gas

under a sequence of aerobic and anoxic conditions. Ammonia oxidizing

bacteria (AOB) which are used for nitrification are the main contributors of

Nitrous Oxide (N2O), a powerful greenhouse gas having a potential of 300

times greater than Carbon Dioxide (CO2) [1] and Nitric Oxide (NO), which

is a toxic gas. Due to unavailability of unified model for capturing the

dynamics of N2O it is difficult to control its emission from waste water plants.

In this study, a model is chosen that captures the dynamics of N2O during

recovery to aerobic condition after a period of anoxia (which is a common

practice in waste water treatment plant) that is used for control purposes.

Further, many of the states (like cell concentration, nitrous oxide and nitric

oxides) used in the model cannot be or are expensive to measure (unknown

states) in a real BNR process. In order to mitigate the emission of N2O its

concentration is first estimated with a soft sensor (Extended Kalman Filter)

and then a nonlinear model predictive control is implemented. Finally, a

control algorithm is provided to address a multi objective problem such as

mitigation of liquid N2O (0:001(mg=L)), maintaining DO (2(mg=L)) and

NH+ 4 concentration (1(mg=L)) [2] in effluent water.

Title : Kinetic Study and Advanced Control of Bechamp Reduction of p-

Nitrotoluene Process in a CSTR

Researcher : Khan, Patan Ameer



Year : 2014

Pages : 43

Call No. : 660.28443 KHA

Acc. No. : T00016

Keywords : Advanced Control, Bechamp Process, Frossling correlation, Kinetics, MPC,

p-nitrotoluene reduction, SBHS

Abstract : In any process control study, the first step is to develop a reliable process

model. This model can then be used for process control and other process

engineering tasks. Further, kinetic study is the heart of the process model of

a Chemical reactor. We in this work present the experimental kinetic study

of aromatic nitro reduction reaction by Bechamp process followed by a

simulation study of advanced control of a continuous reactor. Bechamp

process is a process for the reduction of aromatic nitro compound using zero

valent iron in acidic conditions. The Bechamp process is especially more

popular in the ground water treatment, where the contaminants such as nitro

aromatic compounds (NACs) are converted to less harmful counterpart

aromatic amines [1]. Further, the Bechamp process is also used to produce

aromatic amines from their counterpart nitro compounds. Bechamp process

is one of the specific requirements for most of the pharmaceutical products,

which is an alternative process to catalytic hydrogenation. Usually, in the

Bechamp process, by products such as p-azotoluene and p,p’-ditolylamine are

also obtained along with the amine product. Kinetic study for nitro benzene

and p-nitro toluene (PNT) [1] using Bechamp process has been studied

earlier [2]. The latter study was conducted for the effect of rpm and

temperature with 6-9 μm of iron particle. Further, they also concluded that

the adsorption of the PNT on the solid surface is the limiting step, which was

confirmed by Frossling Correlation [3]. Considering the high cost of such

small sized iron particles, they may not be commercially useful even though

the smaller particles have large surface area. Hence, it is logical to study the

kinetics with coarser iron particles. We in this work have first reproduced

few results reported in Popat and Padhiyar [2] in a 500 ml of batch reactor

with 6-9 μm iron particles at different rpm. Further, we in this work have

focused on the kinetic study of PNT reduction using Bechamp process similar

to Popat [2], though with the coarser iron particles, which is commercially

more applicable. Apart from the effect of iron particle size, the effect of

temperature and the initial composition has also been studied on the Bechamp

reduction of PNT. Chemical analysis has been carried out with Gas

Chromatography (GC) to find out the compositions of various components

involved in the reaction mixture. Further, Frossling correlation of mass

transfer coefficient and rpm has been fitted in the current study. Since the

kinetic study of PNT was not sufficient to develop a process model for the

control of a reactor, we present the advanced process control study of

Bechamp reduction of PNT in a continuous reactor. An advanced control

algorithm, Model Predictive Control (MPC) has been used for this purpose,

which has number of advantages over the conventional single loop, linear

controller, namely PID controller. Before applying the MPC to a reactor, an

experimental study of process dynamics and control has been presented for a

popular temperature control system, namely Single Board Heater System

(SBHS) as well.

Title : Ultrasonication Assisted Synthesis of Few Layers Thick Chemically

Modified Magnesium Diboride Nanosheets

Researcher : Bedar, Amita

Supervisor : Jasuja, Kabeer


Year : 2014

Pages : 39

Call No. : 660 BED

Acc. No. : T00017

Keywords : Chemicals, Magnesium, Selected Area Electron Diffraction, Scanning

Electron Microscopy

Abstract : Graphene has generated enormous research prospects over the last decade

owing to its atomic thin sheet structure that has enabled newer thresholds in

several physico-chemical properties. Recently significant efforts have been

directed towards synthesizing inorganic analogues of graphene which offer a

rich prospect for fundamental and applied science. Boron being the immediate

neighbor of carbon in the periodic table, offers a curious case to be explored

in the search for nanostructures isostructural to graphene. Currently, there

exists no experimental evidence detailing synthesis of 2-D nanostructures

based on boron honeycomb lattice. This thesis reports a chemical method that

we developed to synthesize nanosheets based on boron honeycomb lattice.

This method involves ultra-sonication assisted exfoliation of layered

magnesium diboride in water. This simple sonochemical route results in a

colloidal dispersion of chemically modified MgB2 nanosheets which were

characterized for their morphology and chemical nature. Field emission

scanning electron microscopy (FE-SEM), high resolution transmission

electron microscopy (HRTEM), selected area electron diffraction (SAED)

pattern and zeta particle size analysis revealed that the MgB2 nanosheets had

average effective diameters of ~7–50 μm and average thickness of less than

10 nm. Chemical characterization using Fourier transform infrared (FTIR)

spectroscopy, zeta potential analysis and energy-dispersive X-ray (EDX)

spectroscopy suggests that the chemically modified MgB2 nanosheets

(CMMBs) exhibit a substantial degree of hydroxyl functional groups. This

functionalization stabilizes the colloidal dispersion by facilitating a net

negative charge on the surface of nanosheets. The concentration of ionized

groups present on the nanosheets was quantified by acid-base titration at

different pH values. At pH 7, the nanosheets exhibit a net negative charge.

The discovery of nanosheets comprising boron honeycomb lattice could serve

as an important advance in the science of two-dimensional inorganic

nanomaterials. These nanosheets are expected to provide an avenue to tap

the availability of boron at the atomic level and their functionalized surface is

expected to facilitate the attachment of chemical/biological moieties,

providing rich potential to fabricate and study several unprecedented

constructs.

Title : Aspects of Liquid Antisolvent Precipitation of Nanoparticles of Poorly

Water Soluble Drugs: Nucleation Kinetics, Precipitation Pathways and

Long Term Stability

Researcher : Yadav, Manishkumar D.

Supervisor : Dalvi, Sameer V.


Year : 2014

Pages : 51

Call No. : 660.042 YAD

Acc. No. : T00018

Keywords : Induction Time, Interfacial Energy, Nucleation Kinetics, Non-classical

crystallization, Metastable Zone Width, Solid-Liquid Interfacial Tension,

Self-Assembly, Ultrasound

Abstract : Poor aqueous solubility of drug molecules is a major challenge for the

pharmaceutical scientist involved in drug development. Particle size

reduction to nanoscale appears as an effective and versatile option for

solubility improvement. Unlike the traditional methods used for particle size

reduction, liquid antisolvent (LAS) process offers advantages ranging from

superior particle size control to easy scalability. There are number of factors

in effect during LAS processing. These factors can be grouped into two main

categories; formulation related and process related. In order to design a

robust LAS process, it is extremely important to understand impact of all the

variables such as solvent to antisolvent ratio, temperature, mixing

techniquesetc on the desirable product attributes, such as particle size,

particle size distribution, particle morphology, particle stability, nucleation

kinetics etc. Although several researchers have studied these variables, there

is a widespread disagreement amongst them which makes it difficult to follow

a particular methodology reported. Hence, the objective of the thesis is to

address the gaps in the literature. Nucleation kinetics of a poorly water

soluble drug curcumin during LASprocess in presence of ultrasound and

surfactant has been estimated. The induction time and metastable zone width

(MSZW) for curcumin precipitation and the effect of ultrasound and

stabilizers on these parameters have been estimated. A significant increase in

nucleation rates and decrease in induction time and MSZW was observed for

LAS precipitation carried out in presence of ultrasound. Solid-liquid

interfacial energies were also estimated using induction times obtained

experimentally. It shows that the value predicted using Mersmann equation

and Bennema&Sohnel equation are higher than the experimental interfacial

energies. Additionally, we devised a simple criterion for prediction of a long-

term stability of aqueous suspensions of ultrafine particles of curcumin. A

new “stability parameter” (ϒ0Ɛ/ϒƐ0) has been defined, which is a ratio of non-

dimensional mechanical (mainly ultrasonic) energy (Ɛ/Ɛ0) to the non-

dimensional solid-liquid interfacial energy (ϒ/ϒ0). The stability of aqueous

suspensions of curcumin particles over a period of one year and nine months

have been correlated with this parameter. It was found that precipitations

aqueous suspensions with particle size less than 1µm. It was further observed

that these suspensions remain stable (i.e. no or negligible change in average

particle size) for a period of one year and nine months. On the other hand, the

10) were found to be highly unstable (i.e. the average particle size changes

to engineer stable aqueous suspensions of curcumin particles. Further, it was

found that the use of Mersmann equation to estimate solid-liquid interfacial

surface tensions can help in making this criterion predictive. In addition to

aspects of nucleation kinetics and stability of aqueous suspensions the

precipitation pathways of poorly water soluble drug griseofulvin during

liquid antisolvent precipitation were also explored. It was found that

griseofulvin particles undergo non-classical crystallization pathway during

liquid antisolvent precipitation in presence of ultrasound and

stabilizers.Ultrasound was found to facilitate fusion of assemblies formed

during non-classical crystallization.

Title : Decomposition Kinetics of CaCO3 Dry Coated with Nano-Additives

Researcher : Kumar, Dalip



Year : 2015

Pages : 54

Call No. : 615.70285 KUM

Acc. No. : T00070

Keywords : Decomposition kinetics, CaCO3, surface coating, thermal analysis, non-

isothermal kinetics, dry-coating.

Abstract : Decomposition kinetics of surface coated calcium carbonate (CaCO3) is

investigated using different weight % (0.25%, 1.0% and 2.0%) of nano-

additives (SiO2, TiO2, MgO and Fe2O3). The activation energy was

calculated from model-free iso-conversional technique using differential as

well as integral methods. The result shows that CaCO3 with 1.0% of nano-

additives has lower activation energy then corresponding pure CaCO3. The

catalytic activity of nano-additives is possibly due to the fact that nano-

additives which has higher thermal conductivity act as heat receptor and

increases the surface temperature of the CaCO3. However, coating with

higher % of nano-additives increases the resistance of CO2 diffusion and

increases the activation energy. The results show that there is a significant

reduction in overall heat requirement for ecomposition of CaCO3. This may

be due to phase change of nano-additives which is exothermic in nature and

releases heat within the temperature range where CaCO3 decomposes. Thus,

the decomposition of coated CaCO3 with 1% additives requires lower amount

of heat which has significant implications in limestone based energy intensive

industries. The reaction model for CaCO3 decomposition could not be

predicted by conventional Master plot analysis. However, M´alek’s method

found to be more suitable to determine the appropriate reaction model.

Experimental data was fitted well with the theoretical model proposed by ˇ

Sest´ak Breggren (SB). The parameters (m and n) in SB model and invariance

of activation energy through out the conversion range strongly signify that

decomposition mechanism is single step in nature.

Title : Physico-Chemical Interaction of MgB2 with Water during

Ultrasonication: An Avenue to Realize Boron-Rich Quantum Dots,

Nanodiscs, and Nanoplatelets

Researcher : Gunda, Harini

Supervisor : Jasuja, Kabeer


Year : 2015

Pages : 46

Call No. : 620.118 HAR

Acc. No. : T00073

Keywords : Physico-Chemical, Water during ultrasonication, Nanodiscs, Nanoplatelets,

Layered magnesium diboride, Magnesium

Abstract : Layered magnesium diboride (MgB2), with magnesium atoms sandwiched in

between boron honeycomb planes, present a rich opportunity to access

graphenic forms of boron. It has been recently demonstrated by us that MgB2

crystals can be exfoliated by ultrasonication in water to yield boron-rich

nanosheets. However, the knowledge on the fate of layered metal borides

during ultrasonication in an aqueous phase is in its incipient stages. This

thesis presents a detailed investigation of the physico-chemical interaction of

MgB2 with water during ultrasonication. We observe, that in addition to

undergoing exfoliation to yield nanosheets, MgB2 crystals also undergo a

chemical reaction with water which results in their degradation to form

gaseous boron hydrides and quantum dots rich in boron. These quantum dots

are found to be short-lived and subsequently ripen to form boron rich

nanodiscs and nanoplatelets. While the quantum dots are observed to be <10

nm in lateral dimensions, the nanodiscs and nanoplatelets have a lateral

dimensional range of ~50-400 nm. These nanostructures are few-layer thick

exhibiting a transverse dimension of ~6-8 nm and are found to be decorated

with hydrides and oxy-functional groups. The chemical modification and

nano scaling of MgB2 results in transparent aqueous dispersions which

absorb only in UV regime, making the nanostructure prospective candidates

for fabricating UV absorbing materials. This study presents an entirely new

perspective on the bottom-up formation of planar boron nanostructures. The

ability to form versatile morphologies of boron-rich nanostructures from a

single starting material significantly adds to the current state of knowledge

on boron-based nano structures.

Title : Integrating production control and scheduling based on real-time

detection of divergence

Researcher : Rathi, Preeti

Supervisor : Srinivasan, Rajagopalan


Year : 2015

Pages : 43

Call No. : 660 RAT

Acc. No. : T00081

Keywords : Chain process, Scheduler generates, Real-time, Root-cause

Abstract : Scheduling and process control have been long recognized as the two critical

building blocks in many manufacturing execution ystems. Operating at the

interface between the supply chain and the process, the scheduler generates

a detailed schedule that has to be executed by the process so as to meet the

demands originating from the supply chain. Given the tight interactions

between the two, there has been wide interest in integrating scheduling and

process control. Our key insight is that abnormalities which occur post the

generation of the original schedule, trigger a divergence between operational

targets defined by the schedule and its execution. If left uncorrected, the

abnormalities will propagate between the process and the supply chain. A

timely response could eliminate or minimize such effects. Recognizing this,

we propose a novel framework for integrating scheduling and process control

that detects in real-time when a divergence occurs between the original

schedule and its execution in the process, identifies the root-cause(s) of the

divergence (i.e. the abnormality), and triggers a suitable response from the

scheduler and the process so as to nullify or minimize its effect. In this thesis,

we will describe the proposed approach and illustrate it using an industrially

motivated case study.

Title : Water sustainability and re-use: a case study at Amul Dairy, Anand

Researcher : Tiwari, Sarojini



Year : 2015

Pages : 25

Call No. : 628.30954 TIW

Acc. No. : T00084

Keywords : Water Suatainability, Amul Dairy, Anand, Pollution control boards,

Industries

Abstract : The stringent norms laid down by Pollution Control Boards are forcing

Industries to have efficient waste water treatment plants. However, there are

no protocols to reduce waste water production to encourage water

reclamation and sustainability. The objective of this thesis work is to achieve

the same for a dairy industry. In this work, a unique scheme is suggested

which leads to reduction in water usage. The result shows that more than 5%

of water used per day can be reclaimed. Further, the ETP is modeled and

simulated at steady state with feasible modifications that leads to 10%

increase in energy that can be harnessed from improved Biogas production

rate and 85% reduction in energy usage at the ETP. The possibilities of

nitrous oxide emissions, a green house gas, are simulated. The results fall in

line with the theory available in literature for the same.

Civil Engineering

Title : Mechanical Behavior of Slurry Consolidated Specimens of Cement

Treated Soft Soil Using Shear Strength and CRS Consolidation Testing

Researcher : Bhuria, Nidal Raj

Supervisor : Sachan, Ajanta

Department : Civil Engineering

Year : 2013

Pages : 83

Call No. : 624.151 BHU

Acc. No. : T00005

Keywords : Slurry Consolidated Specimens; Compressibility of soils test; CRS

consolidation--Testing

Abstract : Soft soils are generally known for their extremely high compressibility, low

stiffness & low

shear strength behavior; and cement treatment is one of the most commonly

used techniques to treat such soils to acquire the required engineering

behaviorand specifications to allow the structure to be placed safely on soft

soils without undergoing large settlements. This research is focused on the

evaluation of compressibility and shear strength properties of soft soil due to

cement treatment at different cement contents and curing time. The soft soil

used in this research was found to be too soft (SPT N=1) to collect the

undisturbed samples at soil site. Therefore, disturbed representative samples

were collected from the soil site located at KanjurMarg, Mumbai. The

remolded specimens of collected soft soil with same in-situ water content and

density were prepared in the laboratory by using slurry consolidation

technique. A self-reacting pneumatic slurry consolidometer has been

developed in the laboratory to produce the solid cylindrical specimens of fine

grained soils. These slurry consolidated specimens were used to perform the

UC (Unconfined Compression) tests and CRS (Constant Rate of Strain) tests

to evaluate the shear strength and compressibility properties of soft soil

before and after the cement treatment respectively. The Conventional 1-D

consolidation test (oedometer) was found to be unsuitable for treated soft soil

due to its long testing duration (~10 days), which caused major changes in

compressibility properties of treated soil at chosen curing time.

This motivated the author to develop the 1-D CRS consolidation testing

setup in the laboratory to evaluate the compressibility behavior of treated soft

soils in few hours without any change in chosen curing time. A wide range of

cement contents (2%, 4%, 6% & 8%) and curing time periods (1, 3, 7 & 28

days) were explored in this research to investigate the relationship of

compressibility parameters, shear strength properties, cement content and

curing time period for highly compressible soft soils.

Title : Estimation of Linear Spring Constant for Laterally Loaded Monopile

Embedded in Nonlinear Soil

Researcher : Rani, Shivani

Supervisor : Prashant, Amit


Year : 2013

Pages : 110

Call No. : 624.15 RAN

Acc. No. : T00008

Keywords : Linear spring-mass systems

Abstract : A single large diameter pile, known as monopile, is often provided to carry

all the loads and moments being transferred from the superstructure. In such

a case, accurate estimation of displacement and slope become imperative.

1D, 2D or 3D modelling can be done to simulate deflect tion of pile. For 1D

simulation using Winkler’s model, the spring constant can be calculated from

shear modulus of soil. There are many recommendations available in the

literature to estimate maximum shear modulus of soil. The predicted

maximum shear modulus from various recommendations indicates that the

direct correlations with SPT value have relatively less uncertainty of

prediction. 1D model predictions using existing simple correlations between

spring constant and soil modulus generally overestimate the deflection of pile

when compared to 3D model. Through a comparative study of results from

1D and 3D simulation, a new expression for estimation of spring constant

from soil modulus is proposed which incorporates relative stiffness of soil and

pile. It is also known that soil is nonlinear material and its stiffness reduces

with increase of strain level, hence, it is important to know the amount of

expected lateral strain in soil at different depths. A coefficient has been

proposed to estimate the approximate value of equivalent lateral strain in soil

by assuming strain as a function of top deflection and diameter of pile.

Title : Shear Strength and Compressibility Behavior of Bhavnagar Expansive

Soil with Varying Mineralogical and Swelling Properties

Researcher : Mehta, Bhavini



Year : 2014

Pages : 72

Call No. : 624.15136 MEH

Acc. No. : T00011

Keywords : Bhavnagar, Cation exchange capacity (CEC), Expansive Soil, Specific surface

area (SSA), X-ray diffraction (XRD)

Abstract : Expansive soils contain large amount of montmorillonite clay mineral; which

have tendency to swell by imbibing water in monsoon season & shrink or

become harder by leaving cracks in drier seasons. Excessive drying and

wetting of the soil progressively deteriorates structures over the years and

cause severe damage particularly to the light buildings, and pavements either

through heave or differential settlement. Limited research has been reported

regarding the identification of expansive soils and determination of its

expansiveness & shrinkage-swelling potential based on soil’s different index

properties at various wetting-drying conditions. Few researchers also

worked on the chemical stabilization of expansive soils by mixing various

admixtures and evaluated the method for improvement in soil’s mechanical

behavior in terms of volume stability, strength response, permeability and

durability. The fundamental understanding of expansive soil in terms of

relationship of its mineralogical properties, swelling parameters, consistency

limits, compressibility, and shear strength parameters are still unexplored.

The current research has been performed on expansive soil (black cotton soil)

covering major part of Bhavnagar, located along the coast line of Gulf of

Khambhat in Gujarat. This research is focused on the evaluation of

mineralogical properties, swelling-shrinkage potential, consistency limits,

compressibility and shear strength response of expansive soils collected from

ten different locations of Bhavnagar. X-ray diffraction (XRD), cation

exchange capacity (CEC), and specific surface area (SSA) tests were

performed on Bhavnagar expansive soil to identify its minerlogical properties

at differnt locations. A series of 1D consolidation and UU triaxial tests were

performed on ten soil samples to evaluate the compressibility and shear

strength properties of Bhavnagar soil. This extensive experimental research

work has been used to develop the mathematical correlations for expansive

soils to predict the compressibility and shear strength behaviour of soil based

on its mineralogical parameters, swelling properties and consistency limits.

Title : Effect of Water Content on Shear Strength Behaviour of Micaceous

Kutch Soil

Researcher : Pandya, Pavni



Year : 2014

Pages : 59

Call No. : 624.1517 PAN

Acc. No. : T00012

Keywords : Soild, Water effect, Micaceous Kutch Soil

Abstract : Micaceous soils are generally known for their high compressibility and low

compacted density behavior. Mica flakes in soils are usually small and have

fine sand and silt sizes. Mica particles have an influence on the compaction

properties of soil due to their platy shape, ability to split into very thin flakes

and the inter-space within the thin flakes. The mica flakes also impart

resilience to the soil, which makes it difficult to compact. The spring nature

of mica flakes helps them to recover their shape, when the stress is removed.

In micaceous soils, a mica particle may simply replace an individual granular

particle or fill a void, but as the quantity of mica increases, there is a

corresponding increase in void spaces. Individual mica particles are capable

of spanning over voids instead of filling them. If the mica flakes are

sufficiently numerous to interact, the bridging phenomenon is further

augmented. If mica content in soil is more than 10%, it has strong impact on

compressibility, compressive strength and volume stability of micaceous soil.

Some research has been performed on mica-sand mix to evaluate the effect of

mica on geotechnical behavior of mix. In the current research, effect of water

content on shear strength behavior of naturally available micaceous silty soil

(Kutch, Gujarat) has been studied. The resilience behavior of mica particles

and the presence of water molecules in the inter-space of their thin flakes

were studied to understand the variation in shear strength behavior of

micaceous Kutch soil (14% mica) due to the change in its water content.A

series of shear strength tests were performed on micaceous Kutch soil at

different water content varying from 0% to 23.5%. A series of XRD, SEM

and AFM tests were also performed on Kutch soil to determine the mica

content and understand the size, shape and geometric arrangement of

particles (mica, silt, sand) within the soil mass. Micaceous silty soil samples

were collected at 4 m depth near Dhori site, located in Kutch region (Gujarat);

which had experienced severe liquefaction during Bhuj Earthquake 2001. The

research can be used to understand the effect of mica on liquefaction behavior

of micaceous soils.

Title : Response of Smartphones to Roadway Surface Irregularities

Researcher : Majhi, Subhra

Supervisor : Mukherjee, Abhijit


Year : 2014

Pages : 69

Call No. : 625.7 MAJ

Acc. No. : T00019

Keywords : Accelerometers, Dynamic response, pass filters, Road bumps, smartphones

Abstract : Smartphones are ubiquitous all over the world. As they are carried while

travelling, their in-built accelerometers should feel the irregularities of the

roadway as they are felt by the passengers. Investigations are carried out for

the response of smartphones to roadway surface irregularities when they are

carried by the passengers. A range of road vehicles is mathematically modeled

as mass, spring, and damper systems. The dynamic response of the phone

while passing over a road bump is estimated using the model. The

accelerometer of a smartphone is characterized by oscillating them on a

shaker in the laboratory and comparing the results with that of high precision

accelerometers. The response of the smartphones while travelling in different

classes of vehicles is recorded. The recorded acceleration signals have been

filtered and compared with the predictions of the theoretical model. There is

excellent correlation between the theoretical and experimental results. The

theoretical data is compared with the experimental data to ascertain the

veracity of smartphone in recording data for road surface monitoring. Thus,

smartphones have he potential to automatically monitor the surface quality

of roadways obviating costly manual inspections. The methodology has the

potential to involve user community in the maintenance of infrastructure.

Title : Strain influence diagram for estimation of settlement of isolated and

combined ring footings

Researcher : Samal, Deepak Kumar



Year : 2014

Pages : 87

Call No. : 624 SAM

Acc. No. : T00051

Keywords : ring footings, diagram, soils, Schmertmann’s framework, three dimensional

elastic finite element

Abstract : The Schmertmann’s concept of strain influence diagram provides a

convenient framework for estimating settlement of footings by incorporating

the influence of shear deformations in soils. This method is being widely used

in practice to estimate settlement of circular, rectangular and strip footings

by using the strain influence diagrams available in literature. This study

extends Schmertmann’s framework to propose new set of strain influence

diagrams for isolated and combined ring footings. The proposal is based on

threedimensional elastic finite element analysis for various configurations

pertaining to geometry of rigid ring footings, loadings and soil conditions. In

case of isolated footing, the model has been verified by comparing the

simulation results of circular footing with predictions from the Schmertmann

solution and a closed form solution in elastic domain. The numerical results

indicate that with increase in ratio of inner-to-outer radius of ring footing ‘n’,

the settlement decreases and so does the depth of maximum strain. This

observation has been accounted for by varying the depth of the assumed

simplified strain influence diagram. Based on the new strain influence

diagrams, empirical equations correlating the influence depth with ‘n’ values

are proposed for estimating settlement of ring footings under various degrees

of heterogeneity in sand. Likewise, in combined footings, 3D numerical

modeling and analysis similar to the isolated footings are performed at

various spacings and configurations of ring footing and a detailed procedure

is outlined to obtain settlement for combined ring footings based on a

proposed empirical equation derived along lines similar to the case of isolated

footings. The proposed method is finally validated by comparing with

experimental results available in literature for combined footings.

Title : Landslide susceptibility mapping using GIS

Researcher : Udas, Kaustubh Jayant

Supervisor : Mishra, Vimal


Year : 2015

Pages : 80

Call No. : 624 UDA

Acc. No. : T00052

Keywords : Numerous software packages, 3-D, 3D-FOS, GIS

Abstract : Trimming of slopes as a consequence of proliferating economic growth and

previously existing structures along anonymous unbalanced slopes has been

one of the reasons for originating landslides along hillside areas. Numerous

software packages are available to evaluate multiple 3-D failure surfaces

seeking the lowest FOS e.g. CLARA (Hungr, 1988), 3D-SLOPE (Lam and

Freudland, 1993) and so forth. Nevertheless, these software packages can

replicate individual slopes or part of slopes and cannot capture the larger

areas (regional). Although the potential of GIS for regional slope stability

analysis is well recognized now, until date no specific delineation scheme to

detect the unstable areas could be found in the literature. This study can serve

as a guideline for better planning by the decision makers. The prime objective

of generating Landslide susceptibility maps is achieved by coupling the

deterministic slope stability model with GIS.

The study is divided into two criterions based on critical relief height and

combined 3D-FOS. The decision making criterion considers 3D-FOS with

respect to volume. The preliminary criterion of the delineation scheme can

facilitate in finding regions with ground conditions differing from the

adjacent area with explicit lithological and topographical characteristics

taking into account the soil parameters as well. The secondary criterion based

on 3D-FOS and volume of the possible critical slip surface takes into

consideration the risk associated with the failure. The Susceptibility maps

showing the hazard level will be valuable to identify the critical unstable

zones and assist the policy makers for effective usage of resources in various

paradigms for maintenance.

Title : Estimating dynamic response from pushover type analysis through a

semi-empirical approach

Researcher : Kota, Tejaswi

Supervisor : Basu, Dhiman


Year : 2015

Pages : 249

Call No. : 624 KOT

Acc. No. : T00053

Keywords : Seismic Performance Evaluation, Seismic Performance Levels, Modal

Pushover Analysis, Incremental Dynamic Analysis (IDA), Peak Ground

Acceleration (PGA) Level, Large Scale Seismic Testing (LSST)

Abstract : Performance evaluation of buildings against a given level of seismic hazard

is usually carried out using a displacement-based approach, called pushover

analysis. Among its several variations, Modal Pushover Analysis (MPA) has

become increasingly popular owing to its ability of accounting for the

recorded ground motion explicitly. Structural performance parameters are

usually expressed in terms of displacement and drifts. However, structures

are often equipped with non-structural elements which are sensitive to the

design response parameters like acceleration, velocity etc. Pushover analysis

does not provide any information on the likely dynamic response parameters.

In such a case, Incremental Dynamic Analysis (IDA) can be considered as a

viable approach, which however is computationally expensive and rarely

practiced in a routine job. In this thesis, a semi-empirical method is proposed

which uses the modal pushover response to predict an approximate estimate

of design dynamic response parameters such as, acceleration and velocity.

While doing so, frequency at each analysis stage (i.e., Peak Ground

Acceleration (PGA) level) is first estimated from the pushover curve.

Variation of maximum absolute acceleration across the height is estimated

semi-empirically using the response of linear time history analysis, and

frequency and base shear calculated in MPA. Variation of absolute maximum

velocity across the height is estimated in an analogous way using that of the

absolute maximum displacement response, frequency and modal mass

participation factor at the stage of analysis considered. In order to illustrate

the methodology, three test-beds are considered: 1) a ten-storeyed building

designed conforming to Indian seismic code 2) a seven- storyed existing

building located in seismic zone-IV of India and 3) a ten storey unsymmetric

building designed as per Indian seismic code. Three seismic events recorded

at the Large Scale Seismic Testing (LSST) array in Lotung, Taiwan are used

for the purpose of illustration. Absolute acceleration and velocity

distributions across the height using the proposed approach are found in well

agreement with that from rigorous IDA.

Title : Design of a new passive energy dissipation system for earthquake

resistant structures

Researcher : Reddy, Palugulla Raja Mohan



Year : 2015

Pages : 143

Call No. : 624.1771 RED

Acc. No. : T00056

Keywords : Earthquake-resistant system, Seismic isolation system, Added Damping And

Stiffness (ADAS), Passive and, Active control, Hourglass Added Damping

and Stiffness (HADAS) device, Large Scale Seismic Testing (LSST)

Abstract : The basic principle of conventional earthquake-resistant design that has been

applied for the last 75 years is intended to ensure an acceptable safety level

while avoiding catastrophic failures and loss of life.Over the last half century,

a large amount of research has been conducted into developing innovative

earthquake-resistant systems in order to raise seismic performance levels

while keeping construction costs reasonable.Those structural control

systems are broadly classified into three categories asPassive and,Active

control, andSeismic isolation system. Passive control systems have been

considered as an effective and inexpensive way to mitigate earthquake risks

to the structures.Among different passive energy dissipation systems

available metallic dampers are popular (and inexpensive) choice for an energy

dissipation device because of its relatively high elastic stiffness, good ductility

and it’s high potential for dissipating energy in the post yielding region. One

of the metallic dampers namelyAdded Damping And Stiffness (ADAS) is the

most commonly used metallic dampers in seismic design.

Usually, X-plates are chosen for mounted on a Chevron type bracing are

usually chosen for ADAS. In principle, these devices dissipate energy through

flexural yielding along the out-of-plane direction of the device, with an

assumption of nearly rigid supporting Chevron bracing system along its in-

plane direction. Clearly, these devices will be effective in resisting seismic

excitation along one of the horizontal directions (in plane direction of the

bracing). Other orthogonal components will be resisted by another set of

devices installed in a frame spanning along the other orthogonal direction.

This can be conveniently overcome if a device performing effectively in three

dimensions is thought of.

Three dimensional model of such a device has been proposed in this thesis.

The shape of the proposed damper is in the form of an hourglass, and it is

referred toHourglass Added Damping and Stiffness (HADAS) device. The

HADAS device is capable of dissipating the input energy along both

orthogonal lateral directions, provided the supporting bracing system is

relatively stiffer. However conventional chevron bracings as used in

supporting ADAS devices, have negligible stiffness along the out-of-plane

direction. Therefore, a suitable bracing system, capable of providing stiffness

along any two lateral orthogonal directions are required to be developed for

receiving full benefit from the HADAS devices. Such a bracing system is also

proposed in this thesis.

In order to illustrate the improved seismic capacity of the building after

installation of damper, a ten storey building located in seismic zone - IV of

India is designed conforming to Indian Standards. Three seismic events

recorded at the Large Scale Seismic Testing (LSST) array in Lotung, Taiwan

are used for the purpose of illustration. The improved performance of

building is assessed by comparing peak floor displacement, peak storey drift,

peak storey shear force building without and with the devices.

Title : Development of novel web application for analysis, design and

optimization of trusses

Researcher : Amar Mandhyan

Supervisor : Gaurav Srivastav and Shankarjee Krishnamoorthi


Year : 2015

Pages : 122

Call No. : 620 MAN

Acc. No. : T00066

Keywords : Web application for analysis, optimization, Internet based applications, 2D

plane stress, software

Abstract : With its ever growing popularity, providing Internet based applications

tuned towards practical applications is on the rise. Advantages such as no

external plugins and additional software, ease of use, updating and

maintenance have increased the popularity of web applications. In this work,

a web-based application has been developed which can perform size

optimization of truss structure as a whole as well as topology optimization of

individual gusset plate of each joint based on speci ed load conditions. It

performs topology optimization of 2D plane stress/plane strain problems and

also incorporates a novel method of interpretation of these results in form of

closely possible truss structures. This application is developed using cutting-

edge web technologies such as Three.js and HTML5. The client side boasts

of an intuitive interface which in addition to its modeling capabilities also

recommends con gurations based on user input, provides analysis options and

nally displays the results. The server side, using a combination of Scilab and

DAKOTA, computes solution and also provides the user with comparisons

of the optimal design with that conforming to Indian Standard (IS 800-2007).

It is a freely available one-stop web-based application to perform optimal

and/or code based design of trusses. The web application is accessible in the

IIT Gandhinagar campus on a permanent server 192.168.11.217 as well as

on a back up server 192.168.11.35.

Title : GPR Data Analysis of Weak Signals and GPR Investigation at

Dholavira Site

Researcher : Silky Agrawal

Supervisor : Amit Prashant and Nithin V. George


Year : 2015

Pages : 103

Call No. : 624 AGR

Acc. No. : T00067

Keywords : GPR Data Analysis, Dholavira, Ground penetrating, Geophysical method,

MHz antenna, GSSI system, GPR survey

Abstract : Ground Penetrating Radar is a non-invasive geophysical method used for

subsurface investigation. However, GPR often encounters difficulty in

visualizing the buried target when signals are weak and enveloped by noise,

despite using the best of existing GPR data analysis tools. In this study, new

method has been proposed based on Modified S-Transform to analyze weak

signals of GPR data. The time-frequency analysis has been implemented to

capture the change in electromagnetic waves reflected at the boundary of

dielectric contrast. A series of experimental tests were conducted at different

site conditions and with different

materials using GSSI SIR 3000 GPR system with 400 MHz antenna. An

improved 2-D vertical subsurface profile has been developed using time-

frequency information to locate the target spatially as well as temporally. The

new method has provided better results to improve the target visualization

in case of noisy signals. However, it did not add any significant where

conventional processing could do reasonable. The proposed method is

convenient to use and capable of processing large number of scans effectively.

A new area has been explored at an archaeological site of Harappan

civilization at Dholavira in Gujarat. GPR survey is done using GSSI system

equipped with 200MHz and 400 MHz antenna independently. A wall like T-

shape feature is identified which is further interpreted on the basis of the

available information about Dholavira. Although the GPR data quality is

found to be good, where features were located in conventionally processed

profile, however, profiles processed with proposed method has shown

improvement in the localization

of features and therefore, added confidence in the interpretations of those

features.

Title : Displacement based design framework for confined masonry system

using strut and tie model

Researcher : Vinayak, Ghaisas Kunal



Year : 2015

Pages : 231

Call No. : 692.309941 VIN

Acc. No. : T00071

Keywords : Seismic design, Masonry system, Earthquake prone, Wide Column Model,

Strut and Tie Method, Earthquake Engineering

Abstract : The confined masonry construction has become increasingly popular in

earthquake prone areas due to its satisfactory performance in withstanding

the past seismic events and low construction cost. Computation and design

member force resultants involves numerical modelling. Since FEM is

computationally expensive, simplified approach like Wide Column Model

(WCM) is widely accepted in routine seismic design. However it has its own

limitations such as, inability to capture the stress concentration around the

joints and openings. In such cases Strut and Tie Method (STM) serves as a

viable alternative. A case study is presented identifying the lacunas of the

current STM when applied to confined masonry system. One of the challenge

is the inherent indeterminacy. An approximate approach is proposed to

resolve the issue. Further Performance Based Earthquake Engineering has

been accepted all over the world. However little has been reported to date in

context with the design of confined masonry system. A design framework is

proposed in this thesis, with numerical modelling for performance

assessment. Example problem is included and compared with the

experimental results reported in literature. Overall, the proposed framework

shows a great promise of developing performance based design of confined

masonry system.

Title : Effect of strain rate on shear strength and pore pressure behavior of soft

soil

Researcher : Sudan, Gundeep Kaur



Year : 2015

Pages : 75

Call No. : 624.15136 SUD

Acc. No. : T00074

Keywords : Soft soils, Water, Strength behavior, Kanjurmarg, Plasticity soils

Abstract : Soft soils are highly plastic fine grained soils and known for their high

compressibility, large water content and low shear strength behavior. The

current research is focused on the shear strength behavior of soft soil at

different loading rate, stress history & boundary conditions. The soft soil

samples are collected from Kanjurmarg, Mumbai; and the slurry

consolidation technique is used to prepare the reconstituted specimens of soil

at its in-situ water content & density. Limited research has been performed

on rate dependent strength behavior of soil, which is restricted to small range

of strain rate or non-cohesive/low plasticity soils. An extensive experimental

research has been conducted on Kanjurmarg soft soil (CH soil) by performing

three series of consolidated undrained triaxial compression tests. These CU

triaxial test series explain the following aspects of soft soil: effect of strain

rate on shear strength behavior of NC soil, effect of OCR on soft soil for

overconsolidation ranging from lightly overconsolidated to heavily

overconsolidated stress state, effect of confining pressure on shear response

of NC soil, combined effect of strain rate & confining pressure, combined

effect of strain rate & OCR. A wide range of strain rate; from 0.005% per min

to 5% per min; is used to study the effect of strain rate on shear strength and

pore pressure behavior of soft soil. The effect of boundary conditions and

stress history has been explored by performing CU triaxial tests on soft soil

under confining pressure varying from 100 kPa to 400 kPa and OCR values

ranging from 1 to 10 respectively. The combined effect of strain rate and

OCR has been studied for strain rate of 0.05% per min & 0.5% per min. The

confining pressure influences the strain rate effect on stress-strain & pore

pressure evolution of soft soil. The stress history of soft soil also shows its

impact on shear behavior of soil at varying strain rate. The effect of loading

rate on compressibility response of soft soil is studied by performing 1D

consolidation test at different load increment. SEM, AFM, hydrometer & self

weight consolidation tests are also performed to evaluate the effect of

dispersing agent on behavior of Kanjurmarg soft soil.

Title : Bed Rock Profile Analysis and Interpretation of Archaeological

Features Using GPR at Dholavira

Researcher : Majumder, Mantu



Year : 2015

Pages : 82

Call No. : 551.0954 MAJ

Acc. No. : T00076

Keywords : Archaeology, Bed rock, Dholavira, Harappan, Kachchh, Gujarat, Ground

Penetrating Radar (GPR)

Abstract : Dholavira is one of the five largest Harappan cities located in Khadir Island,

district Kachchh, in the state of Gujarat, India. An ancient Harappan city was

found there with superbly planned, aesthetic architecture and advanced water

management system. A major portion of the city area is unexcavated till

today. Therefore, to explore the city more, to decide the excavation strategy

of the unexplored areas, it was necessary to conduct non-destructive ground

probing survey. Ground Penetrating Radar (GPR) is a non-destructive,

geophysical technique, which provides three dimensional image of the

subsurface features and depth of such features. Two sites were selected for

GPR survey at Dholavira after conducting a through reconnaissance survey

to the site. These sites are located at the east of East reservoir and south of

Lower Town, respectively. GPR survey was conducted using 200 MHz

antenna and GSSI SIR 3000 system. GPR data was processed in conventional

software RADAN 7 prior to interpretation. An average velocity of

electromagnetic wave in the survey area was estimated as 0.125 m/ns which

is later used for time to depth conversion. Low frequency noise and

abundance of multiple reflections masked bed rock reflection making the

interpretation a challenging task. With appropriate filtering and analysis of

data, bed rock profile has been produced of both the surveyed sites. Bed rock

in both the sites was found almost flat except some shallow interruptions in

the bed rock in Site-1. These interruptions might be produced by nature as

no signature of man-made interruptions were noticed. Several linear features

were observed in Site-1 and Site-2. Two distinct rubble deposits were

observed in Site-1. Archaeological understanding of the observed features has

been hypothesized to include existence of water reservoirs, channels, bunds

etc in the surveyed areas. GPR survey provided possible features based on

interpretation of GPR data but more detailed information about dimension

of features was not included in this study due to lack of available techniques.

Title : Characterization of in-plane and out of -plane behavior of infill panels

subjected to thermal exposure

Researcher : Kumar, Puneet

Supervisor : Srivastava, Gaurav


Year : 2015

Pages : 108

Call No. : 628.922 KUM

Acc. No. : T00082

Keywords : Plane behavior, Thermal exposure, Plane loading, Thermal gradients, Fire

safety

Abstract : Several experimental studies have shown that infill panels in a structural

frame have a significant effect on their in-plane as well as out-of-plane

behavior. While masonry infill offers good resistance to in-plane loads, it is

relatively weak under out of plane loading. Exposure to thermal gradients

(e.g. in case of a fire) induces out of plane loads in masonry infill which can

play a key role in its failure. With the advancements in the simulation

techniques, numerical modeling of these structural systems has emerged as a

promising alternative. This study details the development and calibration of

a generic 3D finite-element model to determine the impact of thermal

exposure on structural frames with and without masonry infill panels. The

parametric studies under various thermal exposures on in-plane and out-of-

plane behavior of these structural systems manifest the potential of fire for

inducing instability, and degrading stiffness of the same. The parametric

studies show that even for the least fire severity levels thermal exposure

induced significant instability and stiffness degradation for both structural

systems. Also, these studies reveal that infill-panel not only enhances the out-

of-plane displacements for structural frame but also increases safety risks due

to bulging of infill panel. These parametric studies can be further extended

and the valuable insights from these can be incorporated into the design

process to improve fire safety.

Title : Investigation of moisture transport properties of FAL-G bricks and

cement

Researcher : Bhat, Rujuta

Supervisor : Srivastava, Gaurav


Year : 2015

Pages : 96

Call No. : 693.5 BHA

Acc. No. : T00083

Keywords : Bricks, Cement mortar, Moisture travels, Fly Ash bricks, Computational

models

Abstract : Moisture travels through porous building materials giving rise to many

undesired consequences like structural and cosmetic damage to the structure

and health hazards to the residents. In India, most of the construction

involves masonry and with the advent of load bearing masonry walls or

reinforced masonry and con ned masonry, strength loss causes a potential

risk to the stability of the building, which in turn raises the issue of durability

of building materials. It is necessary to understand how moisture travels

through the walls and make sure that steps are taken in order to prevent any

harmful consequences. Present study focuses on Fly Ash bricks subjected to

moisture transfer and estimation of the di

usion co-e cient of

y ash bricks. Computational models are developed to simulate moisture

transfer in Fly Ash bricks and cement mortar and are veri ed against

experimental results to obtain an expression on moisture di

usivity dependant on moisture content of the brick. These computational

models are employed to perform parametric studies on masonry wall panels.

Title : Effect of agar biopolymer on shear strength behaviour of Sabarmati soil

Researcher : Smitha, S.

Supervisor : Sachan, Ajanta and Gupta, Sharad


Year : 2015

Pages : 68

Call No. : 624.15136 SMI

Acc. No. : T00085

Keywords : Agar Biopolymer, Sabarmati Soil, Sabarmati, River, Earthquake

Abstract : Loose saturated sandy soils are low bearing capacity soils, which are also

prone to liquefaction under earthquake conditions. Many soil treatment

techniques using admixers are available such as cement, chemical grouts,

epoxy, acrylamide, phenoplast, polyurethane etc. However, these admixtures

have negative impact on environment or ecosystem. In the current research,

the agar biopolymer is used to strengthen the loose saturated Sabarmati

sandy soil due to its gel forming capability and environment friendly nature.

Sabarmati soil is treated by using different concentration of agar biopolymer

(0.5%, 1%, 2% & 3%) at different curing time periods of 4hrs, 8hrs, 1day, 3days

& 7days. Shear strength tests are performed on Sabarmati soil before and

after its treatment at different agar concentration & curing time. The

settlement behavior of the treated soil is also evaluated by obtaining vertical

displacement during its shear deformation, which showed significant

decrease in settlement of soil after its treatment. The agar treatment

technique is also evaluated for its applicability in moisture exposed region by

performing shear strength tests on treated soil after water soaking, which

exhibited small reduction in the shear strength of treated soil after moisture

absorption. Thus, the agar biopolymer treatment technique is suggested for

shear strength improvement of sandy soils, including moisture exposed

region with some considerations of high vertical pressures & agar content.

Cognitive Science

Title : Effect of Paced Respiratory Exercise on Retention of Motor Skills

Researcher : Yadav, Goldy

Supervisor : Mutha, Pratik

Department : Cognitive Science

Year : 2015

Pages : 69


Acc. No. : T00072

Keywords : Motor skills, Human behavior, Brain, Respiratory, Retention

Abstract : The ability to learn and perform skilled movements is a hallmark of human

behavior. Activities in the certain brain areas that are involved in acquisition

and retention of motor skills can be modulated by simple exercises involving

changes in breathing pattern and duration, implying that such breathing

exercises may influence the learning and retention of skilled movements. We

have tested this idea in this study. Normal individuals were first trained for a

new motor skill and were assessed for its retention 30 minutes and 24 hours

post learning. The randomly divided experimental groups performed

alternate nostril breathing exercise for 30 minutes either after the learning

session or after the first retention test; while the control group rested for the

same duration. Results indicate a significant difference for retention of the

learned information in the groups that performed breathing as compared to

the group that did not perform breathing. The findings suggest that simple

paced respiratory exercises can be exploited to enhance retention of skilled

movements.

Electrical Engineering

Title : Design of High Resolution Low Power ADC

Researcher : Mohapatra, Satyajit

Supervisor : Gupta, HariShanker

and Mohapatra, Nihar Rajan


Year : 2014

Pages : 65

Call No. : 621.3815 MOH

Acc. No. : T00020

Keywords : CMOS technology, Low power ADC, SAC, ISRO

Abstract : Analog to digital converters are frequently used in imaging payloads

developed for different satellite applications for space based astronomy and

earth observations which include visible imaging, spectroscopy and star-

tracking etc. Apart from this, A/D conversion is the perfect solution for high-

resolution scientific, medical, industrial applications because it has

characteristics of high precision, better accuracy, higher sensitivity and linear

dynamic range. ADC’s are being used for onboard/satellite applications as it

provides high linearity, lower noise and higher dynamic range in CCD and

CMOS detectors. An efficient ADC helps in reducing the overall power

consumption in all payload designs. All imaging payloads consist of video

processors cards which invariably use an ADC for quantizing signal from the

real world sensors. In this work, a 16 bit 5 MS/s pipeline in 0.18μm CMOS

technology ADC is designed with the state of art performance. Since

designing at sub-micron technologies is highly challenging, a systematic

methodology in Matlab is developed to ensure the accuracy and performance

of the design while optimizing power consumption to 140 mW. Amplifiers

with gain as high as 140 dB and large unity gain bandwidth of 260 MHz has

been implemented in this design to take care of its 3.5 bits/stage complexity,

high speed comparators with offset in range of micro-volts, switch

optimization for accurate residue transfer, stage scaling for power

optimization and digital error correction logic implementation are some of

the criticalities of this design. Design methodologies which helped in

achieving state of art performance, design criticalities and challenges faced

during the entire design has been discussed in this report in details.

Title : Online Health Monitoring of the Polymer Electrolyte Membrane Fuel

Cell

Researcher : Laya



Year : 2014

Pages : 44

Call No. : 621.312429 LAY

Acc. No. : T00021

Keywords : Electrochemical Impedance Spectroscopy, Fuel Cell, PEMFC, Polymer

Electrolyte Membrane

Abstract : The Polymer Electrolyte Membrane (PEM) Fuel Cell is a widely researched

fuel cell, and a very promising candidate for alternate power generation.

However, technical issues such as cell flooding and drying prevent its

deployment in many applications. Electrochemical Impedance Spectroscopy

(EIS) is a very powerful technique used to isolate flooding and drying in a

fuel cell. However, the time required to obtain measurements in EIS can

sometimes be too large to cause irreparable damage to the cell, rendering it

a mere post-mortem technique. This is because EIS perturbs a fuel cell with

multiple cycles of a large number of sinusoidal signals at different frequencies.

A new technique is proposed that uses the concept of EIS, but excites the cell

with a chirp signal, allowing scanning a large range of frequencies in a

relatively short time. his technique which we call Fast EIS, is computationally

much faster than traditional EIS. Processing of data obtained with Fast EIS

is done using two methods - the traditional Fourier Transform division

method, and a new Wavelet Coherence method. Simulation results of Fast

EIS with PEMFC models taken from literature are shown with performance

comparable with that of traditional EIS. The information extracted from Fast

EIS is also used for implementing a preliminary control technique to

maintain the health of the fuel cell.

Title : Behavioral analysis of control room operator during plant operation

using display interaction and eye gaze information for effective plant

monitoring

Researcher : Sharma, Chandresh


and Srinivasan, Rajagopalan


Year : 2014

Pages : 57

Call No. : 621.381 SHA

Acc. No. : T00022

Keywords : Distributed Control System, Graphical Display Unit, Human, Plant

Monitoring

Abstract : Safety in process plants is at top in list of issues that are yet to be resolved

fully. Recent accidents and their impact on economy,environment and human

lives have raised this issue once again. There are many causes for such

accidents and many reports have been published to explain why such

accidents had happened. All of these have a common point of view which is

related to control room. Human operator is at the heart of control room as

operator is responsible for proper monitoring and controlling of plant by

observing information from resources present inside control room. A lot of

information, sudden bombardment with lot of alarms under abnormal

situations makes operator paralyzed. A variety of methods are available in

literature such as root cause analysis, removal of alarm chattering etc. to help

operator and make control room much more friendly to operator. But their

implementation and usefulness in process plant is yet to see a significant level

of success. Usefulness of these methods depends on the extent in which these

methods can help operators. In this study an attempt has been made towards

understanding behavior of control room operators. A Graphical Display

Unit(GUI) is designed based on display panel’s outlook in Distributed

Control System(DCS) room.Participants are asked to perform duty of

operators where they are exposed to abnormal situations and asked to control

plant through suitable actions. This is for the first time eye tracker has been

used for this kind of study. A variety of man machine interface data has been

gathered. Results related to effect of training, effect of more exposure to GUI

etc. have been observed. Moreover a metric for operator’s performance based

on GUI interaction data has also been formulated. Eye gaze data has been

used for identifying key factors for effective controlling have been identified

at preliminary level.

Title : Effect of Device Geometries on HCI and PBTI of Gate First High-K

Metal Gate NMOS Transistors

Researcher : Jain, Sharad Kumar

Supervisor : Mohapatra, Nihar Ranjan


Year : 2014

Pages : 59

Call No. : 621.3815284 JAI

Acc. No. : T00023

Keywords : Gate, HCI, High-K Metal, PBTI of Gate

Abstract : As the scaling of MOS transistor is approaching the physical limits, large

leakage current is becoming a major obstacle. Therefore, high-K materials

have been introduced as gate dielectrics in the transistors to further continue

technology miniaturization. However, reliability of MOS transistors with

high- K/Metal gate structure has become a serious concern, because of more

defects in gate dielectric, and introduction of capping layers (La for NMOS

and Al for PMOS). Hot carrier injection (HCI) and bias temperature

instability (BTI) still remain the key reliability issues. In recent technology

nodes, the Positive BTI (PBTI) component cannot be avoided in HCI stress,

and this seriously affects the accurate life time prediction of the device. This

work aims at decoupling of the PBTI component from HCI stress using their

distinct behaviour at elevated temperature. A unique trend of HCI

degradation with the variation in the device width has been shown where

wider devices are more prone to degradation. It can be due to more number

of nonuniformly distributed oxygen vacancies present in the wider devices.

It has also been observed that increase in capping layer (La) thickness in the

NMOS transistor increases the total degradation and we have attributed this

to the stress induced trap generation in the bulk oxide.

Title : Design and Finite Element Analysis of Micromachined Piezoresistive

Polyimide Nanocantilevers for Surface Stress Sensing Applications

Researcher : Chandnani, Ashita



Year : 2014

Pages : 53

Call No. : 621.3 CHA

Acc. No. : T00024

Keywords : CoventorWare, MEMS and NEMS, Nanocantilevers, Surface Stress

Abstract : The rapid progress in the field of micro- and nano- electromechanical systems

(MEMS and NEMS) coupled with the advent of nanotechnology has led to

the development of a very promising field of bioMEMS. A typical example of

this class of devices are MEMS based sensors for biomolecular detection

which use knowledge of various domains like biology, nanotechnology,

microfabrication, material science, optics, electrical and mechanical

engineering. This thesis explores the suitability of polyimide based

nanocantilevers for surface stress sensing applications. Polyimide is a

mechanically flexible biocompatible polymer. In our study, the cantilevers are

modeled and analyzed using the commercial Finite Element Analysis tool

oventorWare. The von Mises stress and the relative percentage change in

resistance of the integrated polysilicon piezoresistor are analyzed by

changing the geometric parameters of the cantilever. The effect of partial and

complete etching of the cantilever structure near the clamped end is also

studied. It is shown that these etched parts act as stress raisers and result in

approximately 50 85% increase in surface stress sensitivity of the device. It is

also shown that the effect of Joule heating on the thermal sensitivity is critical

for overall improvement of signal to noise ratio of the device.

Title : A Step towards Developing a Virtual Reality Based Rehabilitation

System for Post-Stroke Hand Movement Disorder

Researcher : Bhattacharya, Sutapa

Supervisor : Lahiri, Uttama


Year : 2014

Pages : 58


Acc. No. : T00025

Keywords : Electromyogram, Movement Disorder, Rehabilitation System, Support

Vector Machines (SVM)

Abstract : Stroke is a leading cause of adult death and disability, often followed by

muscle weakness, loss of control and coordination in limbs and movement

disorders. Consequently, stroke-surviving individuals with hemiplegia are

often unable to perform simple tasks like opening and closing of their affected

(unhealthy) hand, making them dependent on a caregiver for day-to-day

activities. At the same time their healthy hand retains ability for normal

activities. Rehabilitation aims to improve their ability to use their affected

hand similar to their use of healthy hand. The degree of closure (flexion) of

one’s hand can be mapped from surface Electromyogram (sEMG) signal of

Flexor Carpi Radialis muscle present on the anterior side of one’s forearm.

The different degrees of flexion can be classified with the help of Support

Vector Machines (SVM) using the sEMG signals from the Flexor Carpi

Radialis muscle. In this study we developed a proof-of-concept Virtual

Reality based real-time rehabilitative system for post-stroke hand movement

disorder. Our developed system uses the sEMG data obtained from the

healthy hand of stroke-surviving individuals as training dataset for

classifying the degree of flexion of their respective stroke-affected hand while

they interact with the VR-based tasks, and triggers therapeutic electrical

stimulation to be applied to the muscles of the unhealthy hand of the stroke-

surviving individuals based on their performance feedback. This system can

be used by the patient at home as per his convenience, with minimal

dependency on a physiotherapist or a caregiver. The preliminary results of

testing and feasibility studies suggest that the hand flexion and extension

skills of the participants (six able-bodied and two stroke-surviving persons)

improved with repeated attempts. This indicates that our system has the

potential to take a definite step towards becoming a simple, technology-

assisted solution for rehabilitation of hand movement disorder.

Title : Analysis and Modeling of Stress Overlayer Induced Threshold Voltage

Shift in High-K Metal Gate MOSFETs

Researcher : Parihar, Narendra



Year : 2014

Pages : 59

Call No. : 621.3815284 PAR

Acc. No. : T00026

Keywords : CMOS, High-K Metal Gate, MOSFET, Newer Channel Material, Standard

Abstract : Uniaxial process induced stress along with high-K Metal Gate has been

extensively adopted for 45nm and below CMOS technology node to improve

the performance of deep sub-micron devices. Stress generates strain in the

MOSFET channel which alters the bandstructure of silicon and improves the

performance by enhancing the carrier mobility. Incorporation of process

induced stress using stressed overlayer has become very popular due to its

ease of implementation in standard CMOS process flow. Traditionally,

process induced stress was preferred because of its less bandgap narrowing

and hence less threshold voltage shift compare to substrate induced biaxial

stress. However, in case of devices with high-K metal gate along with

stressed overlayer the experimental data shows a large threshold voltage

shift. Various models have already been proposed to calculate the threshold

voltage shift by in-plane uniaxial stress. Note that the large threshold voltage

shift owing to stressed overlayer and high-K metal gate devices cannot be

explained by conventional in-plane uniaxial stress model. This is because the

stressed overlayer also generates a significant out-of-plane transverse stress

along with the in-plane uniaxial stress. In this work, the stress transfer

mechanism of stressed overlayer and the physics behind the large threshold

voltage shift are explained. A model has been proposed to calculate the

threshold voltage shift due to stressed overlayer for [110] channel oriented

devices for a (100) wafer. The proposed model considers the effects of

conventional in-plane uniaxial stress along with out-ofplane transverse stress

generated by stressed overlayer.

Title : Evaluating the Scaling Effects on Synchronizers and Global

Interconnects in Multicore SoCs

Researcher : Saranya, Yeleswarapu Bala

Supervisor : Mekie, Joycee


Year : 2014

Pages : 59

Call No. : 621.3815 SAR

Acc. No. : T00027

Keywords : Computer Aided Design, Global Interconnects, High Level Design Phase,

Multicore SoCs, PVT, Systems on Chip

Abstract : Aggressive technology scaling enables the implementation of multicore SoCs

(Systems on Chip) for achieving better performance, but it also poses a great

challenge due to various bottlenecks varying from architecture level, design

level, gate level to interconnect level. This thesis evaluates the scaling effects

on two issues- Global Interconnect Delay issue and Metastability issue

during Synchronization. The critical paths of a chip are made of global

interconnects which impact the chip performance. These critical paths need

to be identified and their delays need to be optimized ahead of the HLD (High

Level Design Phase) for the fastest timing closure. This puts the EDA

(Electronic Design Automation) community in a challenging scenario as the

existing CAD (Computer Aided Design) tools do not support this analysis.

This thesis proposes a methodology for synthesizing the critical paths and

automating the design with RTL Compilers. Due to the homogeneous and

heterogeneous clock regions in multicore SoCs, there is a need for

synchronizing the data passing between these clocking domains and hence

study of synchronizers is important. This thesis also focuses on evaluating

the scaling effects on synchronizers and study of metastability parameters

with PVT (Process, Voltage and Temperature) variations. It is found that

synchronizer performance degrades due to technology scaling. Detailed

statistical simulations and an accurate small signal analysis is done to confirm

the above results. The observations match with the measurement trends

proposed in the past. This thesis provides an intuition for the reported

measurement trends from the process simulations.

Title : Terahertz detection with CMOS: Simulation Studies

Researcher : Jain, Ritesh



Year : 2014

Pages : 83

Call No. : 621.381 JAI

Acc. No. : T00028

Keywords : CMOS, High-speed communication, MOS, MOSFETs, Terahertz

Abstract : ‘Terahertz gap’ refers to the still widely un-utilised part of electromagnetic

spectrum. EM waves in THz frequency range have great uses in areas like

security and inspection, spectroscopy and material dentification, medical

diagnosis and high-speed communication. These applications can be

efficiently realized only if inexpensive sources and detectors operating at such

frequencies are developed. Silicon MOSFETs have a cut-off frequency in

range of few tens of GHz. However, active research in recent years has

established that Si MOS transistors can be used as power detectors for

electromagnetic waves up to frequencies in the THz range, i. e. far beyond

their cut-off frequencies. The detection is based on self-mixing of THz signals

in the transistor channel resulting in a photoresponse in the form of a DC

voltage proportional to the power of incident radiation. Based on this

principle, a 1k pixel video camera for 0.7- 1.1 THz imaging application has

been recently realised using 65 nm CMOS technology. The transistor

operation in THz power detectors differs fundamentally from the operation

in typical digital and analog circuits. herefore, it should be expected that the

optimum transistor design for THz detectors is different from that of the

standard CMOS transistors. Device simulations to study the impact of

transistor geometries and doping profiles on the performance of THz

detectors can be very useful and such analysis can be used to suggestfor

improvements in transistor design. In this work, detailed TCAD simulations

to study of the impact of NMOS device design and doping distribution on

detector performance are presented. Extensive time-domain simulations are

used to obtain the THz response and the impact of different device parasitics

and design parameters on this response is analyzed. Improvements in the

device design are suggested to enhance the performance of Silicon MOSFET

THz detectors.

Title : Frequency Driven Alteration In Cellular Morphology During

Ultrasound Pulsing In A Microfluidic Confinement

Researcher : Banerjee, Hritwick


and Chakraborty, Suman


Year : 2014

Pages : 59

Call No. : 621.3 BAN

Acc. No. : T00029

Keywords : Cellular Morphology, Cytomechnical, Microfluidic Confinement

Abstract : To instigate therapeutic potential of low-intensity ultrasound further, it is

essential to characterize the bio-physical interaction of living cells with

alteration of ultrasound frequency. Although, this study is frequently been

the subject of speculation in therapeutic ultrasound regime there has been a

distinct shortage of attempts to characterize in situ physical-biological

interaction in this process. The dearth of effort in this domain inherently calls

for our investigation on frequency dependent shape transition in micro

onfined biological cells. Here, we used a microfluidic platform for single cell

analysis with bio-physical interaction to ultrasound frequency alteration, in

line with the fact that microfluidic channels to a large extent mimic the

confinement effect induced by micro confinement of physiological pathways.

In this dissertation, with the help of series of single-cell direct observation,

we show that low intensity ultrasound frequency alteration would reversibly

perturb cell membrane structure and count for inherent cell oscillation.

However, during post exposure ultrasound period the cytomechnical

perturbation of cell membrane is relatively more compared to ultrasound

exposure period leading to an inherent residual strain which follows a

transition zone near to the resonating frequency of the composite system.

Together, these findings indicate that alteration of low intensity ultrasound

frequency, if applied to a microfluidic platform on the order of minutes, would

produce a reversible effect on physical structures of living cells based on the

system resonant frequency during and post exposure ultrasound pulsing.

Title : Demand Response Algorithm Incorporating Electricity Market Prices

for Residential Energy Management

Researcher : Nair, Arun Gopalakrishnan

Supervisor : Pindoriya, Naran M.


Year : 2014

Pages : 44

Call No. : 621.3042 NAI

Acc. No. : T00030

Keywords : Algorithm, Demand Response, Energy Management, Market

Abstract : Demand Side Energy Management has now been established in the smart

grid framework in order to meet the fluctuating demand supply gap that

exists mainly during peak load periods. Along with the potential of energy

efficiency and conservation measures, due to the increasing use of modern

domestic appliances in a developing country like India, Demand Response

(DR) has gained a lot of importance in the residential sector. Most of the DR

algorithms that have been developed mostly focus on energy consumption

scheduling without considering electricity market prices. In this thesis we

have proposed a DR algorithm for residential customers, which can be used

to optimally schedule appliances, making use of actual day-ahead electricity

market price data and also considering user preferences in the operation of

appliances. The algorithm has been simulated for five different customers

using a flat pricing scheme and two time-differentiated pricing schemes. For

each customer, an estimated saving of around 6% is obtained by using hourly

pricing. Analysis of the results underlines the importance of formulating

effective dynamic pricing policies for successful implementation of DR

algorithms for the residential users thereby tapping into the vast DR

potential that exists in India.

Title : Outage Management System for Power Distribution Network

Researcher : Kumar, Gourav



Year : 2014

Pages : 48


Acc. No. : T00031

Keywords : Advanced Metering Infrastructure (AMI), Outage Management System

(OMS), Power Network, SCADA

Abstract : Outage detection is the first and foremost step in the electric power

distribution Outage Management System (OMS). Unplanned outage

detection is very important for improving the distribution system reliability

and accessibility. Traditionally, customers' trouble calls are the primary

source of outage notification. However, customers report only one third of

outages in the first hour of outages. The advanced metering infrastructure

(AMI) can send outage notifications almost instantly to the utility and could

also give restoration notification when power is restored. AMI data may be

corrupted due to communication channel noise and there may also be

unnecessary outage notifications due to the temporary outages. In this thesis,

an algorithm is proposed to filter out the meter notifications due to corrupted

data and temporary outages of duration less than one minute. An AMI data

filter is modelled by probabilistic and fuzzy membership functions to remove

the corrupted data. Integration of distribution supervisory control and data

acquisition system (SCADA) with AMI for outage location finding is also

proposed by fuzzy membership function based model. Proposed models have

been tested on a radial distribution test feeder and results are analyzed.

Title : Dynamic Modelling Based Reference Current Extraction Technique for

the Control of Shunt Active Power Filter

Researcher : Muduli, Utkal Ranjan



Year : 2014

Pages : 75

Call No. : 621.3 MUD

Acc. No. : T00032

Keywords : Active Power Filter, Current Harmonic, Distribution Networks, IEEE

standards, Passive Filter, Power Quality Problems, Shunt Active Power

Filter

Source Inverter, Voltag

Abstract : In the recent decades, use of power electronic loads have increased because of

their better control and reduced cost. However, these loads draw non-

sinusoidal currents from the utility which affects the power quality of the

system. This has led to the use of passive filters. Though the passive filters

have addressed the issues concerning the power quality, they are encountered

with problems such as resonance, single frequency compensation, system

parameter dependency and bulkiness. This has motivated the researchers to

use active power filter as an alternative to the existing passive filters. Recent

studies have shown that the use of shunt connected active power filter not

only solves the power quality issues, it also solves the generic problems

associated with passive filters. Shunt active power filter (SAPF) works

efficiently for power quality improvement and reactive power compensation.

The performance of the shunt active power filter depends on the method of

reference current extraction. Though the conventional extraction methods

have shown good results for balanced load conditions, they have failed to

accurately determine harmonic and reactive currents, in cases of (a) distorted

and unbalanced supply and (b) unbalanced load. This study presents a method

to estimate the harmonic component and the unbalanced and reactive current

components having fundamental frequency, based on adaptive interference

cancellation theory. An adaptive PI control based DC-link voltage regulator

is developed to avoid the effect of continuous change of load in the

distribution end. Simulations are performed in MATLAB/SIMULINK

environment to verify the feasibility of the proposed method. The results

show that the Total Harmonic Distortion (THD) of utility current from this

method falls well below the prescribed IEEE-P519 limit of 5%.

Title : A Novel Active Anti-Islanding Protection Scheme for Grid-Interactive

Roof-Top Solar PV Systems

Researcher : Varier, Rohith



Year : 2014

Pages : 45

Call No. : 621.3 VAR

Acc. No. : T00033

Keywords : Anti-Island, Distributed Generation, Low Tension, Photovoltaic, Solar

Systems

Abstract : The rising popularity of renewable resources has resulted in increased

penetration levels of Distributed Generation (DG) into the utility grid.

Unintentional islanding is one of the most important safety concerns

associated with grid connected roof-top solar Photovoltaic (PV) systems. The

occurrence of islanding can be fatal to utility workers who may not realize

that the local area is still powered and encounter severe electric shock. For

this reason, DG must be equipped to detect islanding and isolate itself from

the grid immediately, which is commonly referred to as anti-islanding. In

conventional systems, there exists a scenario in which exact balance of PV

generation and load would result in failure of passive anti-islanding schemes.

This problem if rectified by changing the limits of

Overvoltage/Undervoltage (OV/UV) and verfrequency/Underfrequency

(OF/UF) relay, would result in nuisance tripping which causes further

malfunction of the protection system. This thesis work proposes a novel

active anti-islanding scheme for inverter fed roof-top solar PV generation

connected to Low Tension (LT) distribution grid with unbalanced non-linear

loads. The method is based on creating a perturbation in the system using

positive feedback and d-q implementation algorithm. The conventional

passive schemes fail to detect islanding during power balancing conditions,

but the novel active anti-islanding controller ensures that the voltage (or

frequency) at the point of common coupling (PCC) is automatically driven

beyond the threshold preset values. This proposed scheme has been tested in

the presence of non-linear loads and development has found faster islanding

detection compared to the existing methods. Further, the islanding

conditions are simulated and accurately verified on real time.

Title : Power Flow Control of Hybrid AC-DC Microgrid using Master-Slave

Control Technique

Researcher : Kaushik, Rahul Anand



Year : 2014

Pages : 48

Call No. : 621.3 KAU

Acc. No. : T00034

Keywords : Hybrid AC-DC, MATLAB, Master-Slave Control, Power Flow Control

Abstract : Harvesting the maximum possible energy from distributed renewable energy

resources makes the modern electric grid more secure and sustainable.

Considering that fact, various technological advancements and government

initiatives are initiated to connect this distributed generation (DG) through

microgrid to utility grid at point of common coupling. The hybrid AC-DC

microgrid is an upcoming trend of microgrid which not only allows the

connection of variable distributed AC and DC resources to utility but also

reduces multiple conversions in individual AC or DC microgrid. In this

thesis, Master-Slave control technique is proposed for smooth power transfer

between AC and DC microgrid. It overcome various problems like voltage,

frequency variation and circulating current among various DGs in hybrid

AC-DC microgrid and applicable for both grid tied and island mode. A hybrid

AC-DC microgrid with proposed control scheme has been modeled using

MATLAB simulink and real time digital simulator to verify control scheme

for reliable and stable grid operation under various load and supply

conditions.

Title : Finite Control Set MPC based Distribution Static Compensator

(DSTATCOM) for Load Compensation

Researcher : Sreejith, R.



Year : 2014

Pages : 46

Call No. : 621.3 SRE

Acc. No. : T00035

Keywords : DSTATCOM, FCS-MPC, Nonlinear, Synchronous Reference Frame

Abstract : With the proliferation of nonlinear loads especially the power electronic

loads, high harmonic content and poor power factor at the distribution end,

the use of DSTATCOM (Distribution Static Compensator) for reactive

power control is gaining immense popularity. This state-of-the-art dynamic

shunt compensator has immense potential to solve many power quality

problems in power distribution systems. The dynamic performance of

DSTATCOM under nonlinear/ linear and unbalanced loads in 3-phase, 3-

wire 415 V distribution system is studied using Simulink SimPowerSystem

based simulation. The purpose of shunt compensator is to balance the supply

side currents balanced and sinusoidal with unity power factor. The secondary

control objective is to regulate the DC Voltage in order to incorporate for the

losses in the inverter. Two control strategies, namely, Hysteresis based

current control with Synchronous Reference Frame (SRF) theory based

reference current extraction and Instantaneous Symmetrical Component

Theory (ISCT) based reference current extraction are compared and their

performance is evaluated. Here, we have implemented Finite Control Set-

Model Predictive Controller (FCS-MPC) with Instantaneous Symmetrical

Component Theory based reference current extraction method for

DSTATCOM and compared its performance with the PI Controller. Also,

the real time simulation of the proposed model is carried out with the help of

OP5600 Real Time Digital Simulation Test Bed.

Title : Least Distance Predictor Model for Short Term Load Forecasting

Researcher : Jain, Sherry



Year : 2014

Pages : 52

Call No. : 621.3 JAI

Acc. No. : T00036

Keywords : ARIMA model, Load Forecasting, Predictor Model

Abstract : One of the foremost issues concerning the stability of power system around

the world is regulation of frequency. A balance between supply and demand

maintains the frequency constant or within a permissible range. In India, this

balance is regulated by imposing Charges of Deviation on power utilities like

distribution and generation companies that deviate from their scheduled

transactions of energy. This charge is dependent on the system conditions

and varies inversely with the system frequency. Imposition of these charges

on the participants helps maintain grid discipline, increase grid efficiency, and

make the participants more responsible and accountable. The main objective

of this study is to identify a constructive approach to reduce the unscheduled

energy transactions thereby reducing any deviations from the schedule of a

distribution utility. It is proposed that this could be realized in real time

through accurate short term forecasting of load demand. Two year (Jun 2011-

May 2013) past data of daily load demand of Uttar Gujarat Vij Company Ltd.

(UGVCL), a distribution utility in the State of Gujarat is used as a case

example. In this thesis, Seasonal ARIMA model is taken as a base model for

short term load forecasting. It is clearly seen from the results that the model

is not able to capture the characteristics of particular group of days. To

overcome this, a least distance predictor model is developed to forecast the

daily load of the distribution utility. It results in better load characterization

and improved forecast accuracy compared to the similar shape predictor

model. This is achieved without using massive amounts of training data,

thereby reducing time of execution.

Title : Towards a wearable non-invasive low-cost device for measuring

physiological indices: one touch doctor

Researcher : Dhaval Solanki

Supervisor : Uttama Lahiri


Year : 2015

Pages : 57

Call No. : 621.3 SOL

Acc. No. : T00064

Keywords : Blood Pressure, Physiological Indices, Doctor, Physiology, Pathological

state

Abstract : With advancement of healthcare techniques, now-a-days, health monitoring

systems can help to reduce the mortality rate through timely diagnosis of

one’s pathological state. The focus of modern treatment techniques is slowly

shifting to the prevention of disease by adopting preventive measures and

encouraging improved physical fitness, including early warning signs of

diseases. Timely diagnosis and availability of devices that can accurately

measure one’s physiological indices can help an individual to become

conscious of his health condition on the one hand and adopt adequate

preventive measures to address the pathological condition on the other.

However, given the limited availability of proper healthcare resources,

particularly in middle and low income countries, access to cheap and user-

friendly diagnostic techniques or

health diagnostic tools becomes critical. Motivated by this, in our research

we present a novel, non-invasive and cost effective micro-controller based

device that can measure blood pressure, pulse rate, perfusion index,

hemoglobin and saturation of peripheral oxygen level of an individual. We

validated our prototype version of the developed device among few

participants and the initial preliminary results are promising. Additionally,

we carried out Virtual Reality based feasibility study to see the scope of our

device to be incorporated with computer based task involving participant’s

physiology.

Title : A step towards developing an intelligent psychophysiology based

computer assisted interactive system

Researcher : Taruna Yadav

Supervisor : Uttama Lahiri


Year : 2015

Pages : 62


Acc. No. : T00065

Keywords : Psychophysiology, Computer assissted, High sensory awareness,

Electroencephalogram (EEG) signals, Children, Typically developing (TD)

Abstract : Alertness is the state of one’s active attention that is expressed in terms of

high sensory awareness. Many individuals face the problems of unsatisfactory

performance when assigned a task due to lack of alertness which is evident in

day-to-day lives as well. This problem becomes critical for individuals with

attention deficit/hyperactivity disorder and autism due to core deficits.

Though conventional techniques based on observation have been in use,

requirement of skilled interventionist for estimation of alertness has

restricted their applicability. Also, presently available technology-assisted

training approaches are mostly performance sensitive with lesser focus on the

internal cognitive states such as alertness during a task. Considering the

importance of alertness in learning, we have designed a computer based

interactive task environment in which the participants were offered with

three types of tasks by using a switching rationale while monitoring their

performance and alertness through Electroencephalogram (EEG) signals.

Additionally, we have employed a biofeedback approach in the task switching

rationale which made the participants aware of their alertness during the task

which was estimated through physiological indices extracted from the EEG

signal.

In our present work, we have designed a usability study as a proof-of-concept

application. Before applying it for children with attention deficits, we tested

our system by running it through twelve typically developing (TD) children.

This thesis presents the design of the usability study in which TD children

interacted with our computer based system that was adaptive to both the

performance and predicted alertness of the participants. The results of the

preliminary analysis were encouraging and revealed the capability of our

system to have positive implications on the participant’s performance.

Title : Design and Implementation of Efficient Neuromorphic Architectures

Researcher : Tunga, Chandra Sekhar



Year : 2015

Pages : 59

Call No. : 621.395 TUN

Acc. No. : T00069

Keywords : Neuromorphic, Architecture, Address-Event-Representation, Asynchronous,

Synchronous, FPGA

Abstract : Neuromorphic architectures have recently gained attention due to cognitive

computing which requires parallel and distributed architectures. Eventbased

neuromorphic architectures generally use Address-Event-Representation

(AER) and encode the neuron events to efficiently communicate them on a

single channel. The existing work on neuromorphic designs have focused on

biologically-plausible neuron design or on address-event communication.

Generally these designs have been tested on ASICs. However, the turn-

around time and cost of ASIC designs are exhorbitant. On the other hand,

the scalability of the neuromorphic architecture is limited due to interconnect

(wire) delays when implemented as an ASIC. In this work, we present a novel

implementation of asynchronous neuromorphic architecture on a

synchronous FPGA. We propose a highly efficient automated approach to

reduce the space utilization on the FPGA. Generally neurons in a

neuromorphic architecture are arranged in rows and columns, and hence we

refer to them as 2D neuromorphic architectures. In this work, we discuss the

latency, scalability and power issues of conventional 2D neuromorphic

architectures. We present a new three-dimensional (3D) neuromorphic

architecture with a virtual third dimension called layer, which is highly

scalable and allows significant reduction in latency to the conventional

approach. A complex neuromorphic architecture with 625 neurons (25 25

neurons), along with address-event communication protocol has been

implemented on the state-of-the-art 28 nm Kintex KC-705 board. We

demonstrate that the proposed 3D architecture is highly tunable for power,

performance and accuracy, and can be scaled up to 100 100 neurons.

Title : Study of Variability and Technology Scaling on Synchronizers and

Design of Metastable-hard Synchronizers

Researcher : Sinin P., Fathima



Year : 2015

Pages : 60


Acc. No. : T00075

Keywords : Metastable-hard Synchronizers, Scaling, Variability, Process parameters,

MTBF

Abstract : Synchronizers are used at the clock domain crossings and at asynchronous

interfaces to reduce the probability of failure due to metastability.

Metastability parameter plays a key role in deciding the synchronizer

performance. The existing work on synchronizers has focused on

understanding this parameter and its dependence on variations and

technology scaling. The standard cell library flip-flops used as synchronizers

are not really optimized for synchronization. In this work, the properties of

conventional flip-flops and synchronizers are studied and a semi-automated

approach to optimize a standard cell library flip-flop for synchronization is

presented. The resulting synchronizer shows 5 improvement in MTBF

compared to the conventional design. Area and propagation delay

improvement is also obtained. Exhaustive simulations at different technology

nodes (180nm, 130nm, 90nm and 65nm) are done in Cadence Spectre to

validate the analytical results. Opposite trends are observed between

simulations and measurements, but the reasons for these observations are not

well-understood. In this work, this gap has been filled through detailed study

and analysis of the effects of technology scaling on . It is shown through this

work that process parameters fluctuations has significant impact on , and

due to these variations, one may observe devolution or scaling of as

technology scales. We find that among the several process parameters,

mobility and threshold voltage significantly affect. The effect of large

variations in these parameters is that one cannot exactly predict the trend in

as technology scales. In this study, analysis of three different designs are done

to confirm the findings. Further, the difference in between the master and

slave latches have been studied.

Title : Design of complementary high-voltage device compatible with SCL`s

0.18 um CMOS technology

Researcher : Bhoir, Mandar

Supervisor : Mohapatra, Nihar R


Year : 2015

Pages : 87

Call No. : 621.38152 BHO

Acc. No. : T00077

Keywords : Design, High-voltage device compatible, SCLs 0.18 um, High frequency,

CMOS logic gates, CMOS technology

Abstract : With the advent of smart power technology and the concept of system-on-

chip (SoC) for variety of applications, ranging from power management

circuit and driver circuit of RF power amplifiers, integration of high voltage

(HV) devices along with digital logic core has become the need of the day.

Since digital logic core is implemented with continuously scaled CMOS

transistors, it is a challenge to design HV devices compatible with each

technology node. To server such as wise range to applications, these devices

should have complementary counterparts, high breakdown voltage, low on-

resistance, good DC and RF characteristics and good hot-carrier reliability.

All these challenges need to be accomplished within the restriction of having

none or few extra process steps, to limit the additional cost.

In this work, we present optimized process-flow for complementary LDMOS

transistors, which is compatible with SCL’s 0.18 um COMS process-flow.

Simulation based results for N-LDMOS and P-LDMOS transistors report

breakdown voltage greater than 20 v for both and ft /fMAX of 18 GHz/64

GHz and 13 GHz/49 GHZ respectively. These devices, with minimum

degradation of other performance parameters, can provide breakdown

voltage scalability with drift-length. Designed LDMOS transistors also

provide good DC characteristics and can be easily fabricated with just two

additional masks and few process steps on the top of baseline process. The

designed process-flow has minimal impact of mask-misalignment, and

undesirable and inseparable part of deep-submicron technologies processes.

The competitive simulation results show that, these devices when fabricated

would provide a cost-effective solution for applications with operating

voltage upto 20 V.

Title : Experimental investigation of DC-link capacitor voltage balancing in

neutral point clamped inverter

Researcher : Chand, Mohit,

Supervisor : K., Ragavan


Year : 2015

Pages : 62

Call No. : 621.31921 CHA

Acc. No. : T00078

Keywords : DC-link, Voltage, Clamped inverter, Space vector modulation, Nearest three

vector

Abstract : Demand to increase the efficiency and productivity, causes increase in the

power rating of the machines. With increase in power rating, the power

handling capability of the converters is also increased. One way to increase

the power handling capability of the converters is by using the concept of

multilevel. Neutral point clamped inverter is mostly used 3 level inverter in

the industry for high power applications. The problem of DC-link voltage

balancing between the capacitors is one of the major concern of this inverter.

The unbalanced voltages of capacitors causes unbalanced levels in the output

voltages. This unbalanced output levels

in the voltages increases the harmonic content, which in turn cause heating

losses in the machines. Many papers have been published in this area from

last decade and most of these papers uses modulation technique to solve this

problem. In this thesis Space Vector Modulation (SVM) technique is

presented and it is shown that with the proper selection of switching states

this problem can be mitigated.

For nearest vector selection in SVM there are basically two techniques

present in literature namely Nearest Three Vector (NTV) and Symmetric

Modulation Technique (SYM). NTV technique uses proper selection of one

Small vector per switching cycle. The balancing results are demonstrated in

simulation and veri ed experimentally. NTV technique produces variable

switching frequency, this causes unequal loss distribution and sometimes

premature failure of switching devices. This problem of variable switching

frequency is solved by using SYM technique. In this, both the dominant Small

vector are used per switching cycle. The dwell time of the dominant Small

vector is shared between its redundant states. In the literature, mathematical

calculation for obtaining the proper dwell time share is not mentioned.

Proper sharing of dwell time is very important since it results in effective

DC-link voltage control across the capacitors. In this thesis, mathematical

relation for calculating share dwell time for the redundant small vector states

is proposed. It is shown that for effective balancing the share dwell time

depends on phase currents and DC-link capacitor voltages. The derived

calculations are veri ed in a real time simulator and later they are also tested

by hardware in loop. A comprehensive comparison is also done to analyze the

effect of these modulation techniques for DC-link capacitor balancing and the

quality of output waveform they produce.

Title : Analysis of Gate Leakage Current in High-k Metal Gate MOS

Transistors

Researcher : Ganeriwala, Mohit D.

Supervisor : Mohapatra, Nihar R.


Year : 2015

Pages : 62

Call No. : 621.381522 GAN

Acc. No. : T00079

Keywords : Gate leakage, HfO2, CMOS devices, Moores law, MOS transistor

Abstract : Increased power dissipation is one of the major issue for today’s chip

designers. Gate leakage across the gate dielectric being one of the major

component leading to power dissipation in circuits it is necessary to have its

clear understanding. Due to distinctive properties of HfO2 dielectric, used in

advance CMOS devices, the gate current through it is noticeably different

from that of the conventional SiO2 dielectric. Literature reports extensive

work to understand the gate current mechanism through HfO2 dielectric.

However, these studies are either restrictive in terms of the applied bias or

the type of MOS transistor. They also do not elaborate on the reasons for

change in leakage mechanisms with change in gate voltages. Thus the gate

current mechanism through this HfO2 dielectric is still controversial. This

work analyses gate current of both nMOS and pMOS transistors with HfO2

dielectric gate stack. Using measurement and simulation studies we presents

a theory which could consistently explains the gate leakage for the entire

biasing range of both the MOS transistors. This theory also explains the

observed temperature dependency shown by the gate current. The gate

leakage is shown to be dependent on oxide traps which are generated due to

large number of positively charge oxygen vacancies in HfO2. Also the change

in energy level of these traps is shown to be responsible for change in leakage

mechanism. Further it was shown for the first time in this work that the gate

current

is anomalously dependent on the width of the devices. The theory presented

in this work explains this anomalous width dependency and it is attributed to

the annihilation of positively charge oxygen vacancies at the corner of the

activegate overlap region.

Material Science and

Engineering

Title : Improvement of overall equipment effectiveness (OEE) of alumium foil

rolling mill

Researcher : Kumar, Deendayal,

Supervisor : Mukhopadhyay, Jyoti

Department : Material Science and Engineering

Year : 2015

Pages : 89

Call No. : 673.72232:KUM

Acc. No. : T00093

Keywords : Optimization, Recovery, OEE, Management techniques, waste management,

Productivity

Abstract : Aluminum foil is a key material for the food and pharmaceutical packaging

industries. The packaging and non-packaging industries use foil extensively

for their products to protect from possible

deterioration from moisture and ultra violet ray. In the process, it is statically

identified by the Aluminum association as highly demanding commodity.

Formability, printability and excellent barrier properties make the aluminum

foil a perfect choice for protecting and preserving both food and

pharmaceutical items in complex environment. In fact, the foil acts as a

barrier for those items.

Industry expert’s opinion says that the packaging industry in India is

growing at a rate of nearly 15% per annum. It may be observed that the total

demand for aluminum foil is projected around 187,596 tons and 256,562 tons

without export and 206,355 tons and 282,218 tons with export during 2014-

15 and 2017-18 respectively. While India produces only 100, 000 tons per

annum. Therefore, there is a huge gap in supply and demand chain. As the

foil manufacturing plant is very capital intensive, it will be appropriate to

improve the process efficiency of the existing foil rolling mills. Accordingly,

a research has been initiated for the process improvement with the existing

plant of Gujrat Foil limited.

In India aluminum foil is manufactured by cold rolling of the aluminum sheet

whose thickness varies from 650 micrometer to 300 micrometer and width

about 1 meter to 1.5 meters using Achenbach foil rolling mill. For getting

the acceptable quality end products, several factors are responsible. These are

input materials, mill speed, mill temperature, operating condition, lubrication

etc.

In the present communication, three major factors have been focused. These

are Roll change process, Speed optimization for improvement in hour per ton

(HPT) production and Recovery. The data and

experimental work for this paper work are collected and performed in the

facility of one of the highly reputed industries in India called Gujarat Foils

Limited.

In this industry, the roll change process is performed 22 to 24 times on an

average in a month hence, it is very important to reduce the roll change

process time. This can be achieved while using some management techniques,

such as work system engineering, autonomous maintenance, parallel

activities sequencing, Pareto analysis etc. This can be reduced the roll change

process time up to about 15 minutes which significantly adds in total

productivity. Speed optimization was done by collecting the previous 5-6

months data and then the HPT was calculated. The calculated HPT for the

different type of product is then compared with the actual HPT of the month.

The gap between the two is nothing but the saving or improvement in HPT,

when the mill runs on the maximum speed calculated for a particular pass

schedule. The overall recovery of the foil mill is affected due to waste or loss

generated during the production. To improve the recovery of the mill, waste

management techniques are employed and the result gives the acceptable

limit of viii recovery at the end. Finally, the favorable results which help to

improve the productivity of the plant are clearly achieved.

Title : Processing and Characterization of Pcl-Ha Composites for Medical

Application

Researcher : Rooprai, Navjodh Singh

Supervisor : Mishra, Abhijit

Department : Materials Science and Engineering

Year : 2014

Pages : 59

Call No. : 610.28 ROO

Acc. No. : T00043

Keywords : Biomaterials, Hydroxyapatite, PCL-HA composite, Polycaprolactone

Abstract : The focus of this research is fabricating a polymeric composite for biomedical

applications, like bone plates, joint replacement, dental implant etc. and

gaining a better understanding of its properties and behavior. Polymers are

available in a wide variety of compositions, properties and different form that

they can easily be fabricated into complex shapes and structures. But they

have poor mechanical properties compared to bone. The biodegradability and

the possibility to be mechanically strengthened makes polymers very

promising as candidate material for bone replacement. The improvement of

the mechanical properties of polymer can be achieved either by the

modification of the structure of the polymer, or by strengthening of the

polymer with fiber and/or filler. To achieve this objective, the fundamental

properties of biomaterial, polycaprolactone (PCL) and their composite with

hydroxyapatite are examined. PCL-HA composites are fabricated by using

solvent technique. PCL-HA composite samples are prepared to examined

their thermal (TGS and DSC), mechanical properties (density, tensile test, 3-

point bend test and hardness), according to ASTM standard (D638-03 and

D790-03), degradation behavior and viscoelasticity. The results show that

adding HA particles o the PCL matrix improves the mechanical, thermal and

degradation properties of composite structure. The young’s modulus of PCL-

HA composites is similar to that of trabecular bone and, therefore, can be used

for one replacement.

Title : Mathematical medaling of heat transfer, fluid flow and solidification in

melt spinning process

Researcher : Mishra, Rohit

Supervisor : Mehrotra, S P


Year : 2014

Pages : 65

Call No. : 621.4022 MIS

Acc. No. : T00045

Keywords : Melt spinning process, Navier strokes, Volume of Fluids, Amorphous

Ribbon, SIMPLE Algorithm

Abstract : The present work deals with the study of heat transfer, fluid flow and

solidification phenomena of rapidly solidifying amorphous ribbons in the melt

spinning process. Finite volume based mathematical model using Navier-

Strokes equation coupled with heat transfer equations has been developed for

the melt spinning process. The model uses volume of fluid method to capture

free surface interface. The surface

tension force has been coupled with the governing equation in order to get

capillary effects on shape and size of the metal pool. The SIMPLE algorithm

is used to solve the governing equations.

The model Predicts the effects of different process parameter such as wheel

RPM, wheel geometry, superheat, crucible gap and cooling conditions on

ribbon thickness, wheel temperature and melt pool, Transient development

of heat transfer coefficient over wheel surface and wheel temperature have

been studied. The simulation result have been verified with the experimental

data. Reasonably good match between the simulated and experimental results

indicates that the mathematical model in the thesis can be used for optimizing

the melt spinning process.

Title : Evaluation of Forming Limit Diagram of Aluminum alloy 6061-T6 at

Ambient Temperature

Researcher : Kumar, Manoj



Year : 2014

Pages : 92


Acc. No. : T00046

Keywords : Digital Image correction (DIC), Die and Punch, Forming, Forming Limit

Diagram, Genetic Algorithm

Abstract : Forming is a compression-tension process involving a wide spectrum of

operations and flow conditions. The result of the process depends on various

parameters and their interdependence. The selection of these parameters is

still based on trial and error methods. In the present communication a new

approach to optimize the geometrical parameters of components and process

parameters such as blank holder pressure and coefficient of friction etc. is

introduced. The optimization problem has been used with the objective of

optimizing the maximum forming load required for the forming. A Genetic

Algorithm is also used as a tool for the optimization of drawing load and

process parameters. Presently, automobile industries, mainly focus on light

weight and fuel efficient vehicles. Their main challenges are to reduce the

energy consumption and air pollution. Aluminum alloys have excellent

strength, corrosion resistance, recyclability, durability, resistance, ductility

and formability etc. Such unique combination of properties makes aluminum

the best metal to use in automotive and aerospace industries. One automotive

grade Aluminum alloy 6061-T6 is selected for this study. Most of the

material properties for both the usage and formability requirements are

determined by the tensile test. The tensile test can measure not only elastic

properties, but also plastic properties, especially the strain hardening

coefficient and plastic strain ratio, which are very important for formability

analyses. One of the major formability engineering analyses is to measure

strains and strain distributions regarding different stamping quality

concerns. In the present work Digital Image Correlation (DIC) technique is

used. The Forming Limit Diagram is the primary form of representing

formability in the case of sheet metal and it is analyzed in this research.

Title : Formability characterization of AI6014 and DP600 alloys considering

the effects of non linear strain paths, temperature and bending

Researcher : Saxena, Krishna Kumar



Year : 2015

Pages : 111

Call No. : 620.11 SAX

Acc. No. : T00060

Keywords : AI6014 alloys, DP600 alloys, Linear strain paths

Abstract : Sheet metal forming operations are widely used in automotive industries for

manufacturing the automotive panels. The industrial stamping processes are

mainly limited by the appearance of localized necking. This necessitates the

development of a forming limit curve (FLC). FLC is a graphical tool which is

used in finite element based process simulations of sheet metal forming

operations. FLC represents as to what combination of major and minor

strains can be imposed upon the sheet metal during forming. The

conventional FLC has some limitations such as; it fails to predict the

formability in case of nonlinear strain paths and bending operations. The

present work focuses on design of new punch geometry for improved

formability testing considering the effects of non-linear strain paths. Al6014

and DP600 alloys were used in experimentation as they are widely used in

automotive outer and inner body panels respectively. To quantify the effect

of temperature on the FLC of Al6014 and DP600, forming experiments were

carried out at 200 and 250 deg C. Since bending operation is not governed by

FLC, therefore, bending limit curves (BLC) were also determined for Al6014

and DP600. In order to minimize the experimental efforts, theoretical models

are also used to investigate the formability. In this work, FLCs of Al6014 and

DP600 were evaluated using modified maximum force criterion (MMFC) and

M-K model. The FLCs were plotted using different yield functions. Effect of

inhomogeneity factor on FLC level was also investigated.

Title : Thermodynamics of ultra-thin oxide overgrowths on binary Al-based

alloys

Researcher : Darshan Ajmera

Supervisor : Emila Panda


Year : 2015

Pages : 119

Call No. : 620.11 AJM

Acc. No. : T00062

Keywords : thermodynamics, interface energy, surface energy, ultra-thin, [AlMg],

[AlSi].

Abstract : Thermodynamic analyses have been carried out to understand the growth of

ultrathin oxide overgrowths on single-crystalline bare [AlMg] and [AlSi]

alloys due to their dry, thermal oxidation. The parameters considered in this

formalism are alloy composition at the alloy/oxide interface, growth

temperature, oxide-film thickness and low index crystallographic surfaces of

the substrate. Along with the bulk Gibbs free energies of the respective

oxides, the role of energies at the alloy/oxide interface as well as at the

oxide/ambient interface were also taken into the account. Finally, this model

was then compared with the already existing thermodynamic analyses for the

growth of corresponding amorphous oxides on these alloy substrates and are

then validated with the available experimental data from literature. It is found

that, for thegrowth of only crystalline oxides on [AlMg] alloy substrate,

crystalline 2 3 [Al O ] forms for a combination of lower growth temperature,

Mg alloying content at the alloy/oxide interface and oxide-fim thickness,

beyond which crystalline [MgO] formation on this alloy substrate is

thermodynamically stabilized. However, for the growth of a thickening

oxide-film on bare [AlMg] alloy substrate, amorphous 2 3 {Al O } and

crystalline [MgO] are found to be preferred thermodynamically at lower and

higher oxide-film thicknesses respectively. Similarly, for the growth of only

crystalline oxide overgrowths on [AlSi] alloy substrate, formation of

crystalline 2 3 [Al O ] is thermodynamically preferred irrespective of Si

alloying content at the alloy/oxide interface, growth temperature and oxide-

film thickness. Overall, amorphous 2 {SiO } and amorphous 2 3 {Al O } are

found to form at lower and higher oxide-film thicknesses respectively,

followed by phase transformation of amorphous 2 3 {Al O } to crystalline 2

3 [Al O ] on further thickening of oxide-film due to dry, thermal oxidation

of bare [AlSi] alloy substrate only at lower growth temperature and Si

alloying content at the alloy/oxide interface. At higher growth temperature,

amorphous 2 3 {Al O } was found to be formed without transforming to

crystalline

Further, at higher Si alloying content at the alloy/oxide interface, crystalline

2 3 [Al O] becomes thermodynamically preferred without forming an

amorphous 2 3 {Al O } phase. Crystalline 2 [SiO ] was never found to be

thermodynamically favorable for the parameters considered in this study.

These thermodynamic predictions are found to be in agreement with the

experimental findings.

Title : FEM and Experimental Evaluation of J-Integral for Multi-phased

Materials.

Researcher : Sarmah, Abhishek

Supervisor : Mukhopadhyay, Jyoti and Krishnan, S. Athimoola


Year : 2015

Pages : 93

Call No. : 620.1126 SAR

Acc. No. : T00068

Keywords : Multi-phased Materials, Integrity, J-integral, Finite element, J values, Micro-

crack

Abstract : The integrity of any structure is very important so that it does not fail during

its service life. Accordingly,it is of paramount importance that the integrity

of complicated structures such as nuclear power plant, aircrafts, ships,

submarines etc. is not compromised. Weldment is more likely to contain

inherent flaws or micro-crack which may later propagate from weld metal to

the base metal under high stress conditions. Although J-integral is a well

established parameter to determine the fracture when the crack tip plasticity

is considered, but it only holds good when the crack growth takes place in a

homogeneous medium. In case of multi-phase materials such as weldment,

there is no methodology to calculate the J-integral experimentally.

Therefore, a modified J-integral is proposed earlier to calculate J numerically

for multi-phase materials, but it has never been validated experimentally. An

expression to calculate J integral for a compact tension (CT) specimen,

welded transverse to the direction of crack growth from experimental load-

displacement data is proposed. Finite Element (FE) analysis is carried out to

calculate J values, employing modified J-integral for welded CT specimen.

Furthermore, the effect of a/W ratio and HAZ on the fracture toughness of

a welded compact tension is also studied. Scanning Electron Microscopy is

carried out to understand the fracture behaviour of the materials.

Title : New tool design for friction stir weilding of polymer

Researcher : Banjare, Pragya Nandan

Supervisor : Arora, Amit


Year : 2015

Pages : 76

Call No. : 668.9 BAN

Acc. No. : T00080

Keywords : Friction stir welding, High density polyethylene, Mean square deviation,

Welding, Polymer

Abstract : The FSW uses plastic deformation, generated through friction and

deformational heating to join the workpiece. Therefore, the technique is very

popular and well adopted in Automobile industry for joining of Aluminium

sheets. The low frictional heat generation, low thermal conductivity and

different solidification behavior of the thermoplastics, hinders the use of FSW

for joining. The conventional FSW process in the thermoplastics gives poor

weld strength, due to low frictional heat and poor thermal conductivity. A

new tool design is proposed and tested for the Friction stir welding of

polypropylene. The newly developed tool provided with a resistance-heating

element inside the tool, resolves the low frictional heat problem in case of

FSW of thermoplastic. The improvement in weld strength of the welded

samples found to be more than double compared to conventional FSW weld.

Microstructural analysis of the joints were done to see the effect of

microstructure on the weld strength.

The tool heating, tool shoulder diameter, tool RPM and travel speed are

important process parameters in FSW that affect the weld strength. The

taguchi technique is used to optimize the process, by determining the relative

effect of the the process parameters over the weld strength. The newly

developed tool is promising for the industrial use, for joining of

thermoplastics.

Title : Rheological studies of coal fly-Ash slurries

Researcher : Prasad, Vighnesh

Supervisor : Mehrotra, S. P. and Thareja, Prachi


Year : 2015

Pages : 137

Call No. : 621.4023 PRA

Acc. No. : T00086

Keywords : Rheology, Coal, FLY-ASH, Power plants, Pipe sooner, Sodium salicylate,

Ammonium bromide

Abstract : Coal based thermal power plants play a major role in current energy policy

in India. Indian coal has high ash content up to over 45%. India produced

163.56 million tonne of ash in 2012-13 and is expected to produce about 300

million tonne by 2017 and 900 million tonne by 2031-32. Hence, there is a

critical need to handle this large amount of fly ash in the most economical

way with minimum environmental damage. A suitable disposal technique is

required to utilize this huge amount of fly ash. One major potential usage of

fly ash is hydraulic transportation of the fly ash slurry and use it for mine

filling. This is going to be an economically and environmentally viable

technique for mine site rehabilitation and acid mine drainage control in mine

areas. An understanding of the flow properties of fly ash slurry is important

for effective transportation and further utilization. This study presents the

results of rheological studies conducted on Fly-ash samples collected from

Centre for Fly-Ash Research & Management (C-FARM), New Delhi. The

main problem associated with hydraulic transportation of fly-ash slurry is the

gravitational settling of fly-ash particles in the pipe sooner than desired. Our

results show that preparing the fly ash slurries in equimolar aqueous

solutions of Cetyltrimethyl Ammonium Bromide (CTAB) and Sodium

Salicylate (NaSal) prevent the settling of fly ash particles. Results from

rheological studies on fly ash slurries with 10 - 60wt% fly ash loading and at

different additive concentration show that all slurries are shear thinning

when sheared from 1S-1 – 400S-1. The zero shear viscosity of the slurries

increases with the fly ash loading. The rheological data are fitted to a power

law model which shows that the shear thinning exponent (n) and consistency

factor (k) depend on the loading of fly ash. These results help in

understanding the relationship between fly-ash slurry rheology and the flow

characteristics in circular pipes. We found minimum power consumption and

minimum energy dissipation rate during hydraulic transportation for the

highest loading i.e. Cw = 0.6 (60wt %) in tap water at 0.1% additive and 0.5

m of pipe diameter.

Title : Comparative study of fatigue crack growth rate of SS 304H Cu for two

different heats

Researcher : Desai, Bhupatrai Umang

Supervisor : Mukhopadhyay, Jyoti and Matcha, Nani Babu


Year : 2015

Pages : 68

Call No. : 620.1123 DES

Acc. No. : T00087

Keywords : Fatigue crack, Heats, Temperatures, Nuclear fuel complex, Austenitic

stainless steel

Abstract : The current trend in the power generation industries is to operate at higher

pressure and temperatures to meet the demand of power. In addition, the e

ciency of the power production can be increased due to increase in the

temperatures, at the same time pollution can also be reduced. Countries like

U.S., China and U.K. are currently running full-

edged programs to initiate Advanced Ultra-Super Critical (AUSC) Power

Plants which operate at high temperatures and pressures above the critical

point of water. Keeping energy production in the world wide, India also aims

to develop such power plants. However, the material which can withstand at

elevated temperatures is a challenging task in worldwide particularly for

creep and fatigue properties. Thus, the materials development program has

already begun in India in collaboration with R& D institutes and industries.

Under this program, materials are being developed by Nuclear Fuel Complex

(NFC) indigenously. These materials further characterised for various

properties by Indira Gandhi Center for Atomic Research (IGCAR,

Kalpakkam) in order to compare the various properties internally available

grades of same materials. Under this program, various materials are being

tested for properties like, creep, fatigue crack growth rate, fracture toughness

etc. since, the thermo-mechanical,

ow induced vibrations can lead to the crack nucleation and growth. Thus, the

damage assessment procedure for structural

integrity assessment is required. The fatigue crack growth rate studies are

necessary for damage assessment.

This thesis work was carried out to evaluate fatigue crack growth

characteristics in Paris regime for the material Austenitic Stainless Steel

304H Cu. In this study, comparison was made between indigenously

developed SS 304H Cu and imported SS 304H Cu. The experiments were

carried-out in laboratory air at various temperatures: 300 K, 873 K, 923 K,

973 K and 1023 K. The fatigue crack growth rates were compared for both

the materials. It was found out that, indigenously developed material was

more resistant to fatigue crack growth than the mported material. The

possible reason behind this di

erence in the fatigue crack growth characteristics is attributed to presence of

ne precipitates in the metal matrix which resulted in to crack branching.

Moreover, it was observed that presence of twins is more in the case of

indigenously developed material than in the imported material. This results

in crack tip tress-shielding during the crack growth.

Title : Evaluationm of Hoop direction tensile properties of 9cr-ODS and T91

steel nuclear fuel clad tubes using ring tensile test

Researcher : Azad, Abdur Rahman Al

Supervisor : Mukhopadhyay, Jyoti and Laha, Kinkar


Year : 2015

Pages : 108

Call No. : 621.48 AZD

Acc. No. : T00088

Keywords : Hoop direction, 9CR-Ods, Nuclear fuel, Ring, Power plants, fuel burn

Abstract : Nuclear power plants are powered by nuclear fuel pellets stacked inside fuel

clad tubes. These tubes act as housing for the fuel pellets and remain as the

first barrier for the radioactive material. The present focus of nuclear power

plants is to increase the efficiency of the power plants by increasing the fuel

burn up. However, this enhances cladding degradation which may increase

the chances of cladding failure. During operation the fuel clad tubes

experience maximum value of stress in the hoop or transverse direction which

results in failure of the tubes. Hence, it is very important to determine the

mechanical properties in hoop direction of the clad tubes. Ring Tensile Test

is used for measuring the mechanical properties of tubular specimens along

hoop direction. The testing method consists of loading the ring along the

transverse direction by applying double D inserts inside the ring. However

there are some limitations in this procedure which includes bending of sample

during loading and the friction between the inner surface of ring and outer

surface of the loading pin. Like in conventional tensile test there are no

standards available for the specimen geometries and test procedure. The

present work focuses on the selection of suitable combination of specimen

geometries for ring tensile test, mitigation of bending of sample during

loading and to reduce friction between the inner surface of ring and outer

surface of loading pin. The optimized specimen geometries and testing

parameters were used to measure the hoop direction tensile properties T91

and 9Cr-ODS steel clad tubes. To understand the effect of temperature on

mechanical properties of T91 and 9Cr-ODS steel clad tube ring tensile tests

were carried out both at room temperature and elevated temperatures.

Fractography studies were also performed on the fractured specimens to

understand the fracture behavior at different temperatures by using scanning

electron microscopy.

Mechanical Engineering

Title : Computational Aerodynamics and Flight Dynamics of Perching

Maneuver of Unmanned Aerial Vehicles

Researcher : Dwivedi, Vinay


Department : Mechanical Engineering

Year : 2014

Pages : 101

Call No. : 629.1323 DWI

Acc. No. : T00037

Keywords : Computational Aerodynamics, Flight dynamics, Perching Maneuvers,

Propeller performance, Unmanned Aerial Vehicle

Abstract : The aerodynamics and flight mechanics of the dynamic maneuver of a low

speed propeller powered puller-type Unmanned Aerial Vehicle (UAV) have

been modeled solving unsteady incompressible Navier-Stokes equations and

six-DOF rigid body flight dynamics equations. The flight maneuver of this

UAV is accomplished by swiveling the outboard wings relative to the inboard

wing fixed to the fuselage to change the angle of attack towards stall angle

to slow down the UAV. To set the stage for a computational aero-mechanics

modelling, the performance characteristics of a propeller and the interference

aerodynamic effects of its installation on the UAV aerodynamics is assessed

numerically. Along with time accurate studies, standard UAV aerodynamic

characteristics are modeled on the basis of high fidelity computational

aerodynamics. The flight trajectory of the UAV considering the variation of

aerodynamic characteristics during the flight maneuver is computed as part

of the overall computed solution by coupling the erodynamics and flight

dynamics. A comparative study for various configurations in terms of swivel

point and perching rate are also addressed in order to better comprehend and

understand the phenomenon.

Title : Design And Performance Calculation of a Solar Aided Super Critical

Coal Power Plant with Thermal Energy Storage

Researcher : Gupta, Sonia

Supervisor : Bhargav, Atul


Year : 2014

Pages : 80

Call No. : 621.042 GUP

Acc. No. : T00038

Keywords : Parabolic Collector Field, Performance, Solar aided coal fired plant, Thermal

energy storage

Abstract : To reduce fuel costs and to reduce the impact of power generation on the

environment, retrofitting traditional coal powered power plants with clean,

renewable solar thermal power has been proposed. However, a detailed

estimate of the costs and benefits of such a retrofit need to be quantified in

the context of the specific plant location and its load profile. This work

presents the concept of Solar Aided Power Generation (SAPG), where a

conventional coal fired power plant is hybridised with the parabolic trough

field. The operation of a 660 MW supercritical coal fired plant in Gujarat,

India integrated with solar field of parabolic trough collectors has been

designed for part load conditions. A solar field, based on calculations of solar

angle is proposed. A comparative study of both North-South alignment and

East-West alignment has been made. The main feature of this hybrid system

is the molten salt carrying the solar energy. The energy from a fixed solar

field size, coupled with a thermal energy storage mechanism has been

designed to replace steam in one of the feed water heaters. The effect of this

retrofit on the net efficiency of the coal plant has been examined. Also, a

concept of two tank direct molten salt storage has been introduced for this

hybrid plant. When thermal energy storage is removed, the improvement in

the coal plant efficiency is in the range of 7-14 %. Calculations for the storage

systems and the salt-water heat exchanger are also shown. The improvement

in the net efficiency of the coal plant comes out to be in the range of 1-3% by

using two tank direct thermal storage system.

Title : Computational Modeling of the Condensed Phase Aerosol Based Fire

Extinguisher

Researcher : Sharma, Himanshu



Year : 2014

Pages : 79

Call No. : 621.811 SHA

Acc. No. : T00039

Keywords : Aerosol, Chemical Pellets, Condensed Phase Fire Extinguisher, Solid

propellants

Abstract : The computational modeling of a novel condensed phase aerosol based fire

extinguisher is considered in this study to assess its operational details and

performance. A solid propellant is present inside the canister which is ignited

using piezoelectric actuators producing hot fire extinguishing gases. The

cooling of these hot gases is facilitated by a matrix of chemically active

cooling pellets placed along the canister which condenses hot gas and

discharges solid aerosol particulates. The initial experimental investigation

of the extinguisher carried out at the premises of the industrial partner

showed that improper cooling of the hot gases by the pellets can lead to high

temperature of the effluent gases and sparks at the exit. This provided the

basis for exploring computational modeling to develop a better

understanding of the physics of the extinguisher performance and to develop

improved experimental procedures on the basis of the results from a

computational fluid dynamics model. Initial modeling efforts centered on the

finite volume solution of the Euler equations modified to incorporate the

essential physics of the problem such as mass flow from the pellets and the

heat transfer. On the basis of the computed results from this simplified model,

a multi-component combustion gas flow inside the extinguisher is computed

by solving high fidelity three-dimensional Navier-Stokes equations. While

detailed chemical kinetics are not accounted for in the computation, initial

experimental estimates of these processes are used in the simulations to

account for the effects on dynamics of the process. The computed results

show how improper cooling by the pellet region may lead to hot spots in the

extinguisher. These results will be used to improve the experimental design.

Title : Computational Modeling of Wing In Ground Effect Aerodynamics

Researcher : Prasad, Rachit



Year : 2014

Pages : 82

Call No. : 629.1323 PRA

Acc. No. : T00040

Keywords : Fixed and Rotary Wing Aerodynamics, Ground Effect Vehicles, Wing in

Ground Effect, Wings near Wavy Free Surfaces, Volume of Fluid

Abstract : The impact on the aerodynamics of a fixed wing, UAV and rotary wing, due

to the presence of a ground and free surface in close proximity, is studied

using computational methods in this work. The Reynolds Averaged Navier

Stokes (RANS) equation are solved for the fluid flow, while the interface

between the two fluids is captured using the Volume of Fluid (VOF)

technique. The motivation behind this work is to study the effect of wavy or

calm surface of a water body or sea on the fixed wing and rotor aerodynamics

and compare the difference in the vicinity of a rigid ground surface, which is

the approach normally taken to model ground effect in most of the existing

computational studies. In order to study the perturbation of the free surface,

this study uses a multiphase approach to capture the free surface, rather than

pre defining it as a rigid boundary. Waves of different patterns are generated

by using appropriate source terms in the momentum equation (by way of a

numerical wave maker) and the effect of these on the fixed wing and rotor

aerodynamic characteristics are analyzed. The results observe a significant

variation in aerodynamic quantities depending on the wave characteristics.

Title : Recursive and Delayed Reconstruction of Unknown Inputs for

Dynamical Systems

Researcher : Chavan, Roshan Anandrao

Supervisor : Palanthandalam-Madapusi, Harish


Year : 2014

Pages : 44

Call No. : 620.1074 REC

Acc. No. : T00041

Keywords : Instrument faults, Dynamical Systems, zeros

Abstract : Most dynamical systems have inputs driving the system and the resulting

outputs. The inputs to the system can be known or unknown. Unknown

inputs in a dynamical system may represent unknown external drivers, input

uncertainty, state uncertainty, or instrument faults. In this dissertation we

consider delayed recursive reconstruction of states and unknown inputs of a

systems. That is, we develop filters that use current measurements to

estimate past states and reconstruct past inputs. We further derive results for

convergence of these filters in terms of multivariable zeros and show that

these methods are a more general form of the methods in the literature. Next,

we explore the applicability of input reconstruction methods above to address

command following problems in which the objective is to ensure that the

system output follows a desired reference command. The key idea is to

assume that a control input exists that yields the desired reference output

exactly and then use input reconstruction methods to estimate that control

input. With this end in view we explore a few control schemes based on the

filter-based approach to input reconstruction and demonstrate the efficacy of

these methods with illustrative numerical examples.

Title : CFD Based Coal Combustion and Erosion Modelling for A 660 MWE,

Super-Critical Tangentially Fired Pulverized Coal Boiler

Researcher : Pillai, Manish

Supervisor : Narayanan, Vinod


Year : 2014

Pages : 67

Call No. : 621.4023 PIL

Acc. No. : T00042

Keywords : Coal Combustion Modelling; ddy Break-up Model; Erosion Modelling;

Super-Critical Boiler; Oka Model

Abstract : A CFD based numerical modelling of coal combustion is performed in

conjunction with erosion modelling for two samples of blended coal to

estimate combustion characteristics, particle and gas flow field and erosion

due to ash particles for a large scale, tangentially fired 660 MWe supercritical

pulverized coal boiler. The numerical simulation was performed on

commercially available CFD code, STAR-CCM+. The Eularian approach is

used to model gas phase and Lagrangian approach to model particulate phase.

The particle track is obtained in terms of particle velocity and temperature.

The ash particle velocity and trajectories are utilized to predict erosion on

boiler components. The coal combustion with coal moisture evaporation, coal

devolatilization and char oxidation is considered incorporating eddy break-

up model (EBU) for continuous phase. The ash particle track obtained from

coal combustion modelling is used to model erosion on internal pressure

parts of the boiler, using Oka erosion model. The simulation results show the

good agreement with the flow pattern, gas velocity, particle velocity, and

temperature distribution with existing boiler. The predictions made for

erosion have been found to be in good agreement with the erosion trend

observed on existing boiler.

Title : Computational Modelling of Positive Displacement PumpsBoiler

Researcher : Bhandari, Neelesh



Year : 2014

Pages : 67


Acc. No. : T00043

Keywords : Gear pump; Lobe pump; Overset mesh; Positive displacement pumps; Rope

washer pump; Volume of fluid (VOF)

Abstract : The computational modelling of positive displacement pumps based on

Reynolds Averaged Navier Stokes (RANS) equations on unstructured

meshes by the finite volume method is addressed in this study. The Volume

of Fluid (VOF) method is used to capture the interface between the working

fluid and air. Turbulence is modelled using a two equation k-ɛ RANS

turbulence model. The main aim of the study is to compute the flow variables

in the pump and to extract pump performance characteristics over a range of

varying flow conditions. Experimental studies of pumps only provide data

related to flow rates and heads which the pumps can achieve, while with

computational study, it is possible to obtain insight on the flow physics inside

the pump, and use these insight to propose design improvements for more

efficient pump operation. Overset mesh techniques are used to facilitate the

motion of the pump components in this computational study. Leakage

between pump components has also been considered in this computation. The

pump characteristics have been defined in terms of volumetric efficiency,

effective flow rate, pressure rating and pump torque. These performance

characteristics are used for evaluating optimum range of pump speed, with

highest efficiency and flow-rate. This study aims to provide a basis for further

research on several design aspects of the pump.

Title : High- fidelity computational assessment of the performance of a

vertical axis wind turbine

Researcher : Sudani, Jay Arvindbhai



Year : 2015

Pages : 143

Call No. : 621 SUD

Acc. No. : T00061

Keywords : Vertical Axis Wind Turbine; Dual Counter Rotating Vertical Axis Wind

Turbine; Aerodynamics; Computational Fluid Dynamics; Large Eddy

Simulation; Wind Energy

Abstract : Even though Vertical Axis Wind Turbines (VAWT) are known to have

lower efficiencies than Horizontal Axis Wind Turbines (HAWT), their

simple construction and inherent design features qualify them as viable and

cheap options for low cost wind energy systems. Hence, the VAWT serves

as a viable application in rural sectors where it can be extensively used for

electricity generation, pumping water and so on. Computational modeling of

the flow fields in the vicinity of a VAWT for four different tip speed ratios of

the turbine blade is the focus of this work. Here the flow is numerically

computed using two different turbulence modeling approaches namely the

Reynolds Averaged Navier-Stokes (RANS) with the Spalart-Allmaras

turbulence model, which is popularly used for external aerodynamic analysis

and the Large Eddy Simulation (LES) with the Wall-Adapting Local-Eddy

Viscosity (WALE) model. The prime focus of this study is on LES approach

of turbulence modeling, where large scale motion is computed explicitly and

small scale motion is modeled. This approach can accurately capture

turbulent flow structures and the effect of large scale motions caused by wind

forces and their fluctuations. The key differences between the capabilities of

both the modeling approaches is reported here. The effect of the close

proximity of the turbines on their power coefficients is numerically studied

using dual counter rotating VAWT rotors placed closed enough to each

other. Improvement in the performance of the dual rotor is found due to the

mutual aerodynamic interference. This study will lay the foundation for

further studies such as design optimization of VAWTs, optimization of inter-

turbine spacing in order to maximise the wind power density of the wind

farm, etc.

Title : Impact of fan pressure change and rack layout on data center thermal

performance

Researcher : Pratik Suryakant Shirbhate

Supervisor : Atul Bhargav


Year : 2015

Pages : 110

Call No. : 621.402 SHI

Acc. No. : T00063

Keywords : Thermal Performance; Fan Pressure; Computational modelling; Boundary

Condition; CFD model

Abstract : Data center is a housing facility for computing related devices and associated

components such as computer servers and telecommunication equipment.

Due to the rapid progression of technology with high speed processors in

internet application, data centers have been the focus of thermal management

efforts. The increased server heat density in a server rack is major concern

for data center operators. Effective and efficient removal of server heat is

necessary to maintain safe working environment inside the data center.

Therefore there is a need for data center thermal management.

Although a number of experimental and numerical studies have focused on

fluid flow and heat transfer within data centers, systematic studies of server

rack layout, the effect of server fans and validation of numerical model with

laboratory prototype are missing from the literature.

In this thesis work, we have addressed and provided an efficient solution to

this issue by changing rack layout in a data center. We have analysed the

effect of server fan pressure rise, and compared the conventional data center

layout with an alternative “S-Pod” layout using computational fluid dynamics

simulations. We have presented the theoretical basis for scaling down a data

center to a lab-scale prototype, and then validated numerical models with

experimental results on this prototype. We have also studied effectiveness of

passive rear door heat exchanger modelled using porous media approach.

Conventional data center showed better thermal performance for the server

rack fan pressure of 10 Pa while S-Pod layout showed better thermal

performance at 5 Pa. Similar thermal profiles are observed for conventional

layout and S-Pod layout having an additional 20% heat load. The use of

Richardson’s number in dimensional analysis has been found very promising

in building an experimental prototype of data center. The improvement in

performance indices (SHI, RHI, RCI and RTI) in S-Pod layout (scaled down

data center) has been observed to be 10.5%, 4.5%, 6.2% and 3.8% based on

simulation result and 5.9%, 3%, 3.3% and 3.5% based on experimental result.

Through experiments and CFD simulations, we demonstrated that during

various transients such as air-conditioning failure and a load fluctuations, S-

Pod layout results in consistently (relatively) superior performance.

Results indicate an optimum value of fan pressure change and an additional

20% heat load bearing capacity in S-Pod layout because of confined

distribution of air flow. Considering all the indices cumulatively, S-Pod

layout is almost 5-10% more efficient as compared to conventional layout.

These studies quantify the improvement in performance, and are significant

for research and data center designers.

Title : Lattice Boltzmann method for applied aerodynamics problems

Researcher : Kanoria, Akshay Anil,



Year : 2015

Pages : 82

Call No. : 620.1:KAN

Acc. No. : T00090

Keywords : Lattice Boltzmann Method; GPU and Multi-Core High Performance

Computing System; Parallel Programming; Particle Based and Continuum-

based Flow Solvers; Overset Meshes

Abstract : The advent of cheap massively parallel computer architectures in accelerators

such as Graphical Processing Units (GPUs) has provided an impetus for

computing fluid flow and heat transfer problems using particle methods such

as Lattice Boltzmann Method (LBM) where, instead of solving the continuum

Navier Stokes equations, the discrete Boltzmann equation is solved with

collision models such as Bhatnagar-Gross-Krook (BGK) and the moving

particle semi-implicit method based on Lagrangian formulation of

computing thermo-fluid problems. The LBM is an efficient parallel algorithm

for simulating single-phase and multi-phase fluid flows and for incorporating

additional physical complexities. It is especially useful for modeling

complicated boundary conditions and multi-phase interfaces. It is

traditionally defined on two- or three- dimensional discrete structured

lattices to model transport processes for different boundary conditions and

has been established as a reliable flow solver and prediction tool in recent

years. The current work explores and demonstrates the use of two different

open source solvers implementing the LBM, namely, Sailfish (which runs on

GPU cores) and Palabos (which runs on Multi-Cores). Various benchmark

problems such as driven lid cavity problem, flow past bluff and streamlined

bodies are addressed for validation and an insight into the reliability of the

LBM for problems in applied aerodynamics. Further, to understand the

parallel efficiency of implementing the LBM algorithm on high performance

computing (HPC) platforms, a serial LBM code written in Matlab for flow

past an airfoil has been parallelized using parallel Matlab (P-Matlab) on a

Multi-Core and GPU based HPC system to accelerate the computations

while ensuring high order accurate results. Traditional implementations of

LBM uses Cartesian mesh of lattices, which require special treatment on

irregular boundaries (which are typically encountered in applied

aerodynamics) for the specification of boundary conditions and this is often

cumbersome to implement in a code. The implementation of this special

boundary condition treatment on the computed results is verified on selected

benchmark problems and the results compared with the corresponding

results from finite volume continuum based flow modeling techniques which

is the standard practice in Computational Fluid Dynamics (CFD). The work

also describes an attempt at the implementation of overlapping meshes inside

the open-source solver Stanford University Unstructured (SU2) as a prelude

to implementing overlapping mesh system of lattices for LBM and laying a

starting point for addressing moving boundary problems in applied

aerodynamics in the future.

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