The Network Era

» A B O U T T H I S I S S U E

8 IEEE CONTROL SYSTEMS MAGAZINE » AUGUST 2007

A fter centuries of advance-ments in science and engi-neering, what might be the

principal technological paradigm ofthe 21st century? Would youbelieve dots and arcs? As a doo-dling exercise, take a piece ofpaper, make about 30 dots, andthen connect the dots as you see fit,with, say, 100 arcs. You can draw atrandom or you can create an aes-thetic design, but however you doit, in the end you have a network.The dots are nodes, some kind ofentities, and the arcs are edges,some kind of connector. You canthink of the dots as cities and thearcs as roads that connect the cities.Or, the dots may be people, and thearcs might represent the fact thattwo people know each other. Thereare endless interpretations.

If you wish, you can make yournetwork more intricate. You couldendow some arcs with arrows,perhaps representing one-waystreets. You could assign a weightto each arc representing, for exam-ple, a distance. Or, you could coloreach dot so that some are red andothers are yellow.

Then you can ask lots of mundanebut tricky questions. If any of the arcscross each other, you might wonderwhether you can untangle andredraw your network so that no arcscross. You might wonder whetheryou could recolor the dots so that nored dot connects to a yellow dot. Youmight select a pair of dots and askwhether there is a sequence of arcsthat takes you from the first dot to thesecond dot. You might wonder whatthe largest or average distance is fromone dot to another dot.

Contributors

Bert and Niki Tanner

Amara, Naomi, and Lily LeonardBack row: Joshua Bishop, David Thorsley,Samuel Burden, Eric Klavins, and John-Michael McNew. Front row: Kevin Oishi, NilsNapp, and Fayette Shaw

Calvin andChaouki Abdallah

Francesco Bullo

Ílker Üstoglu

Jorge Cortés

Prabir Barooah andJoão Hespanha Sonia Martínez

Sam, Danny, and Maks Grünbaum

Robyn, Ethan, and Derek Paley

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Dots and arcs, witharrows, weights, andcolors. Is this the para-digm of science andtechnology for the 21stcentury? It might be.Much of science andengineering is con-cerned with the gloriouscontinuum problemsthat have received enor-mous attention over thelast two centuries, suchas heat flow, wave propagation, andturbulence. But advances in those areashave brought us networks of trans-portation systems, communicationlines, and economic activity. We alsobecame aware of ecological systemsand their increasing fragility, terroristsand their secretive networks, thehuman genome and its combinatorialcomplexity, and epidemics that travelat lightning speeds. Dots and arcs.

When Chaouki Abdallah and Her-bert Tanner approached me aboutorganizing a special section on net-works, I was only vaguely aware ofthe impact that these notions werehaving on science and technology.This issue of IEEE Control Systems

Magazine provides aglimpse of the signifi-cant impact that net-works are having, notonly as a mode ofthinking but also as atechnology that isaffecting our infra-structure.

The special section inthis issue has six featurearticles. After the intro-duction by Chaouki and

Herbert, Albert-László Barabási dis-cusses the ramifications of smallworlds and scale-free networks, prop-erties by which a network can be bothrobust to random failure but fragileto systematic attack. The article byEric Klavins discusses the ability ofcomponents to spontaneously self-assemble into useful systems, notunlike molecules assembling intolarger molecules. The article by PrabirBarooah and João Hespanha presentsstrategies for collecting and process-ing data from a network to estimateglobal quantities, such as time orlocation. Next, inspired by flocking ingroups of animals, Sonia Martínez,Jorge Cortés, and Francesco Bullo dis-

cuss how local interaction amongnodes leads to global properties.Along the same lines, Derek Paley,Naomi Leonard, Rodolphe Sepulchre,Daniel Grünbaum, and Julia Parrishpresent control strategies that giverise to coordinated motion.

In addition to the special section,this issue of IEEE Control Systems Mag-azine includes numerous articles ofspecial interest. For “Applications ofControl,” Sandipan Mishra, JoshuaCoaplen, and Masayoshi Tomizukaexplain how to implement iterativelearning control for wafer processingwhen the disturbances aren’t quiteperiodic. In “Focus on Education,”Emmanuel Collins, Jr. and AbdollahHomaifar describe the developmentand status of control engineering pro-grams at historically black colleges anduniversities in the United States. Wealso have a report on the 45th Confer-ence on Decision and Control held inDecember 2006, as well as a productreview on the Polynomial Toolbox.

As usual, we appreciate your feed-back. We’re the dots, and the arcs areavailable. I hope to hear from you.

Dennis S. Bernstein

EDITOR-IN-CHIEFDennis S. BernsteinUniversity of MichiganAerospace Engineering Dept.1320 Beal StreetAnn Arbor, MI 48109-2140 USAPhone: +1 734 764 3719Fax: +1 734 763 0578dsbaero@umich.edu

ASSOCIATE EDITOR, BOOK REVIEWSScott R. Ploen Guidance and Control AnalysisGroupJet Propulsion LaboratoryCalifornia Institute of Technology4800 Oak Grove DrivePasadena, CA 91109 USAScott.R.Ploen@jpl.nasa.gov

EDITORIAL ASSISTANTSusan L. Kolovson

ASSOCIATE EDITOR, EDUCATIONAlexander Leonessa University of Central Florida

ASSOCIATE EDITOR, HISTORYKent LundbergMassachusetts Institute of Technology

Andrew Alleyne University of Illinois

Randal W. BeardBrigham Young University

Darren Cofer Rockwell Collins Inc.

Henrik Gollee Glasgow University

Europe and Africa: Levent GuvencIstanbul Technical University

Asia and Australia: Shuzhi Sam Ge National University of Singapore

Karlene HooTexas Tech University

Pablo A. Iglesias Johns Hopkins University

Carl R. KnospeUniversity of Virginia

Daniel E. Rivera Arizona State University

Raja Sengupta University of California, Berkeley

Jan Swevers Katholieke Universiteit Leuven

Dawn Tilbury University of Michigan

Panagiotis Tsiotras Georgia Institute of Technology

North and South America: Tyrone Vincent Colorado School of Mines

Conference Activities: Zongli Lin University of Virginia

New Products:Vikram Kapila, Polytechnic University

TECHNICAL ASSOCIATE EDITORS

CORRESPONDING EDITORS

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AUGUST 2007 « IEEE CONTROL SYSTEMS MAGAZINE 9