CPCC Seminar by Prof. Zhi (Gerry) Tian
Title: Enhancing Access to the Radio Spectrum - Compressive Spectrum Sensing
Date: Feb. 13, 2013, Wed.
Time: 1:00 - 2:00 pm
Venue: EH 2430
This talk has two parts. In the first part, I will briefly discuss several NSF programs
related to Communications, Sensing and Cyber-Physical Systems. In particular,
I will give an introduction on NSF's initiative on enhancing access to the radio spectrum (EARS).
In the second part, I will present a technical discussion on compressed sensing in statistical signal
processing, where compressive sampling of random processes is of interest. Our new framework allows
for accurate estimation of useful statistics from compressive measurements using simple least-squares
solutions, even when the random signal of interest is non-sparse. As an example, I will present
a cyclic feature based compressive spectrum sensing approach for wideband cognitive radios.
Wideband communication signals possess unique two-dimensional sparsity structures in both
the frequency domain and the modulation-dependent cyclic frequency domain. Exploitation of
these sparsity elements not only reveals important features
of the modulated signals for detection and classification purposes,
but also results in fast reconstruction of the cyclic statistics and hence reduced sensing time.
Using the new framework of compressed sensing for random processes, compressive spectrum
sensing becomes feasible even for (non-sparse) crowded spectrum.
Dr. Zhi (Gerry) Tian is a Professor in the Department of Electrical and Computer Engineering
of Michigan Technological University. She is currently on leave to serve as a Program
Director in the Division of Electrical, Communications and Cyber Systems (ECCS)
of the Engineering Directorate at the National Science Foundation.
Her research interests lie in digital and wireless communications,
wireless sensor networks, and signal processing. She has served
as Associate Editor for IEEE Transactions on Wireless Communications
and IEEE Transactions on Signal Processing. She is an IEEE Fellow.
CPCC Seminar by Prof. Walid Saad (Univ. of Miami) and Prof. Zhu Han (Univ. of Houston)
Title: Toward Self-Organizing Wireless Small Cell Networks (by Prof. Saad)
Date: Dec. 7, 2012, Fri.
Time: 2:00 - 2:30 PM
Venue: EH 2430
The deployment of small cells serviced by low-cost, low-power stations
(e.g., femtocells, picocells, microcells, etc.) is envisioned to
significantly improve the performance of next-generation wireless
networks. Maintaining and managing the heterogeneous and dense network
architecture resulting from small cell deployments mandates a paradigm
shift from centralized optimization toward self-optimizing,
self-organizing, and self-configuring networks. In this talk, we study the
potential of developing self-organizing algorithms, based on notions from
game theory and learning, for addressing various challenges in small cell
networks. In particular, we focus on two key problems: (i)-
Noncooperative and matching games for strategic access policies and
user-to-access point association, and (ii)- Cooperative games for spectrum
leasing and interference management. For each problem, we present the key
concepts, discuss the proposed solutions, and shed a light on future!
opportunities. Finally, we conclude with an overview on future research
directions and challenges in the area of small cell networks and adjunct
Prof. Saad'S BIOGRAPHY
Walid Saad received his B.E. degree in Computer and Communications
Engineering from the Lebanese University, Faculty of Engineering, in 2004,
his M.E. in Computer and Communications Engineering from the American
University of Beirut (AUB) in 2007, and his Ph.D degree from the
University of Oslo in 2010. Currently, he is an Assistant Professor at
the Electrical and Computer Engineering Department at the University of
Miami. Prior to joining UM, he has held several research positions at
institutions such as Princeton University and the University of Illinois
His research interests include wireless and small cell networks, game
theory, cognitive radio, wireless security, and smart grids. He has over
60 international conference and journal publications in these areas. He
was the author/co-author of the papers that received the Best Paper Award
at the 7th International Symposium on Modeling and Optimization in Mobile,
Ad Hoc and Wireless Networks (WiOpt), in June 2009, at the 5th
International Conference on Internet Monitoring and Protection (ICIMP) in
May 2010, and at IEEE WCNC in 2012.
Title: Compressive Collaborative Spectrum Sensing for Cognitive Radio (by Prof. Han)
Date: Dec. 7, 2012, Fri.
Time: 2:30 - 3:00 PM
Venue: EH 2430
To increase spectrum utilization, cognitive radios can detect and share
the unused spectrum. However, each cognitive radio can only scan a
narrow band of spectrum, and the scan is time consuming. This bottleneck
limits spectrum sensing in terms of bandwidth, speed, and accuracy.
Aiming at breaking this bottleneck, we propose compressive collaborative
spectrum sensing based on the recent technique of compressive sensing,
which senses less and computes more. It lets a sensor acquire a signal,
not by taking many samples, but rather by measuring a few incoherent
linear projections. The sensor transmits the linear projections to a
receiver, where the signal is reconstructed by an algorithm. For many
applications, such a shift of resource demands from pre-transmission to
post-transmission can be of great benefit. This is true for spectrum
sensing, where the benefit is less and faster sensing at the cognitive
radio nodes, as well as reduced transmission from these nodes to the
Prof. Han'S BIOGRAPHY
Zhu Han received the B.S. degree in electronic engineering from
Tsinghua University, in 1997, and the M.S. and Ph.D. degrees in
electrical engineering from the University of Maryland, College Park, in
1999 and 2003, respectively.From 2000 to 2002, he was an R&D Engineer of
JDSU, Germantown, Maryland. From 2003 to 2006, he was a Research
Associate at the University of Maryland. From 2006 to 2008, he was an
assistant professor in Boise State University, Idaho. Currently, he is
an Associate Professor in Electrical and Computer Engineering Department
at University of Houston, Texas. His research interests include wireless
resource allocation and management, wireless communications and
networking, game theory, wireless multimedia, security, and smart grid.
Dr. Han is an NSF CAREER award recipient 2010. Dr. Han has 6 best paper
awards in IEEE conferences, and winner of Fred W. Ellersick Prize 2011.
CPCC Seminar by Prof. Michele Zorzi
Title: Optimal Transmission Policies for Energy Harvesting Communication Devices
Date: Dec. 4, 2012, Tues.
Time: 11:00 - 12:00
Venue: EH 2430
Energy Harvesting (EH) is a new paradigm in Wireless Sensor Networks
(WSNs): sensor nodes are powered by energy harvested from the ambient,
rather than by non-rechargeable batteries, thus enabling a potentially
perpetual operation of the WSN. However, Energy Harvesting poses new
challenges in the design of WSNs, in that energy availability is
random and fluctuates over time, thus calling for radically different
energy management solutions. In this talk we investigate the following
fundamental question: how should the harvested energy be managed to
ensure optimal performance? First, we consider a sensor powered by EH
which senses data of varying importance and reports them judiciously
to a Fusion Center. Assuming that data transmission incurs an energy
cost, our objective is to identify low-complexity policies that
achieve close-to-optimal performance, in terms of maximizing the
average long-term importance of the reported data. We first consider
schemes that rely on the assumption of perfect knowledge of the amount
of energy available in the battery. Subsequently, we investigate the
design of operation policies that maximize the long-term reward under
imperfect knowledge of the State-Of-Charge (SOC). Moreover, for both
scenarios, we explore the impact of time-correlation in the EH
process, showing that simple adaptation to the state of the EH process
yields close-to-optimal performance, without requiring full knowledge
of the SOC of the battery.
Michele Zorzi is a Professor at the Department of Information
Engineering of the University of Padova. Prior to his current
appointment, he was employed at the Politecnico di Milano, the
University of Ferrara and the University of California at San Diego,
with which he still has an active collaboration. He received a PhD in
Electrical Engineering from the University of Padova in 1994.
Prof. Zorzi was the EiC of the IEEE Wireless Communications magazine
in 2003-2005, and the EiC of the IEEE Transactions on Communications
in 2008-2011, and has served on the Editorial Boards of the top
journals in his area of research and on the Organizing and Technical
Program Committee for many international conferences. He is an IEEE
Fellow. His main research interests are in the area of wireless
communications and networking, sensor networks and IoT, underwater
communications and networks, and energy-efficient protocol design.
CPCC Seminar by Prof. Chengshan Xiao
Title: Optimal Linear Precoding for Finite Alphabet Signaling in Wireless Systems and Networks
Date: Nov. 29, 2012, Thu.
Time: 11:00 - 12:00
Venue: EH 2430
Finite alphabet signaling refers to commonly used discrete-constellation modulations in practical communication systems, such as PAM,
PSK or QAM. In this talk, we will target at how to increase data rate or throughput via linear precoding in wireless systems and
networks such as multiple-input multiple-output (MIMO) systems, multiple access channels, broadcast channels, wiretap channels, and
cognitive radio networks. We will present backgrounds, theoretical results, hardware implementation, and experimental results for
maximizing the mutual information-based achievable data rate or throughput. Our results demonstrate that precoding for finite alphabet
signaling can be radically different from the precoding (or power allocation) for Gaussian signaling. Our examples show that the
finite-alphabet signaling-based approach provides not only higher achievable data rate but also lower coded bit error rate than the
approaches that design the precoder with Gaussian input assumption. Further research topics will be discussed in this talk as well.
Chengshan Xiao is a Professor of Electrical and Computer Engineering at Missouri
University of Science and Technology, Rolla, Missouri.
His research interests include wireless communications, signal processing, and
underwater acoustic communications. He is the holder of
three U.S. patents. His algorithms were implemented in Nortel's base station
radios after successful field trials and network
integration. Prof. Xiao is an IEEE Fellow and the Editor-in-Chief of IEEE Transactions
on Wireless Communications. He is also a Member of the
Fellow Evaluation Committee, a Member of the Board of Governors, and
a Distinguished Lecturer of the IEEE Communications Society.
Previously, he served as the founding Chair of the IEEE Technical Committee on
Wireless Communications and the Technical Program
Chair of the 2010 IEEE International Conference on Communications, Cape Town, South Africa.
CPCC Seminar by Prof. Michael Langberg
Title: Three Open Problems in Network Communication
Date: Nov. 27, 2012, Tue.
Time: 11:00 - 12:00
Venue: EH 2430
In this talk I will discuss three natural open questions in the context of
multi-source/ multi-terminal network communication via network coding.
(a) What is the maximum loss in communication rate experienced from
removing a single unit capacity edge from a given network? (b) What is
the maximum loss in rate when insisting on zero error communication as
opposed to vanishing decoding error? (c) What is the maximum loss in
rate when comparing the communication of source information that is
``almost'' independent to that of independent source information?
Recent results including intriguing connections between the three
questions will be presented.
Based on joint work with Michelle Effros.
Michael Langberg is an Associate Professor in the Mathematics and
Computer Science department at the Open University of Israel.
Previously, between 2003 and 2006, he was a postdoctoral scholar in
the Computer Science and Electrical Engineering departments at the
California Institute of Technology. He received his B.Sc. in
mathematics and computer science from Tel-Aviv University in 1996, and
his M.Sc. and Ph.D. in computer science from the Weizmann Institute of
Science in 1998 and 2003 respectively.
Prof. Langberg's research is in the fields of Information Theory and
Theoretical Computer Science. His work focuses on the design and
analysis of algorithms for combinatorial problems; emphasizing on
algorithmic and combinatorial aspects of Information Theory, and on
probabilistic methods in combinatorics.
CPCC Seminar by Prof. Wing-Kin (Ken) Ma
Title: Semidefinite Relaxation and Its Applications in Signal Processing and Communications
Date: Nov. 9, 2012, Fri.
Time: 2:00-3:00 PM
Venue: EH 2430
Semidefinite relaxation (SDR) has recently been recognized as a very
useful and handy tool in signal processing and communications. It is
a powerful approximation technique for a host of difficult optimization
problems, generally taking the form of nonconvex quadratically
constrained quadratic programs. SDR has found numerous applications;
among them particularly important applications are MIMO detection
(which covers multi-user, multi-antenna, space-time,...), transmit
beamforming (which covers classical single-cell multiuser downlinks,
multicell coordinated multiuser downlinks, unicasting and multicasting,
cognitive radio, physical layer security, one-way and two-way relays...),
and sensor network localization. And the application scope is still
expanding. This talk aims at giving an overview of SDR. I will describe
essential ideas and practical deployment aspects of SDR, and summarize
some of the key theoretical results offered by optimization researchers,
which will be presented from a non-expert viewpoint. And certainly, the
talk will cover the important SDR applications, and some very forefront
advances in those applications.
Wing-Kin Ma received the B.Eng. degree in electrical and electronic
engineering from the University of Portsmouth, Portsmouth, U.K., in
1995 and the M.Phil. and Ph.D. degrees, both in electronic engineering,
from the Chinese University of Hong Kong (CUHK), Hong Kong, in 1997 and
2001, respectively. He is currently an Assistant Professor with the
Department of Electronic Engineering, CUHK. From 2005 to 2007, he was
also an Assistant Professor with the Institute of Communications
Engineering, National Tsing Hua University, Taiwan, R.O.C. Prior to that,
he held various research positions with McMaster University, Canada;
CUHK; and the University of Melbourne, Australia. His research interests
are in signal processing and communications, with a recent emphasis on
MIMO communication, convex optimization, blind source separation, and
signal processing for hyperspectral remote sensing. Dr. Ma is currently
Associate Editor of IEEE Signal Processing Letters. He is also Guest
Editor of IEEE Journal of Selected Areas in Communications on the special
issue "Signal Processing Techniques for Wireless Physical Layer Security,"
and IEEE Signal Processing Magazine on the special issue "Signal and Image
Processing in Hyperspectral Remote Sensing." He previously served as
Associate Editor of IEEE Transactions on Signal Processing, and Guest
Editor of IEEE Signal Processing Magazine. He was a Speaker of a Tutorial
in EUSIPCO 2011. He is a recipient of the 2009 Exemplary Teaching Award
given by the Faculty of Engineering, CUHK, and co-recipient of an ICASSP
2011 Best Student Paper Award and a WHISPERS 2011 Best Paper Award.
CPCC Distinguished Seminar by Prof. P. R. Kumar
Title: The Challenge of Cyber-Physical Systems
Date: Oct. 22, 2012, Mon.
Time: 3:00 PM
Venue: EH 2430
Cyber-physical systems (CPSs) are the next
generation of engineered systems in which computing, communication,
and control technologies are tightly integrated.
We present a historical account of paths leading to the
present interest in CPSs.
Research on CPSs is fundamentally important
in many important application domains such as
transportation, energy, and medical systems. We overview
CPS research from both a historical point of view in terms of
technologies developed for early generations of control
systems, as well as
several foundational research topics that underlie
this area. These include issues in data fusion,
real-time communication, security,
middleware, hybrid systems and proofs of correctness.
P. R. Kumar obtained his B. Tech. degree in Electrical Engineering
(Electronics) from I.I.T. Madras in 1973, and the M.S. and D.Sc. degrees in
Systems Science and Mathematics from Washington University, St. Louis, in 1975 and 1977,
respectively. From 1977-84 he was a faculty member in the Department of Mathematics
at the University of Maryland Baltimore County. From 1985-2011 he was a faculty member
in the Department of Electrical and Computer Engineering and the Coordinated Science
Laboratory at the University of Illinois. Currently he is at Texas A&M University,
where he holds the College of Engineering Chair in Computer Engineering.
Kumar has worked on problems in game theory, adaptive control, stochastic systems,
simulated annealing, neural networks, machine learning, queueing networks,
manufacturing systems, scheduling, wafer fabrication plants and information theory.
His current research interests are in wireless networks, sensor networks, and
networked embedded control systems. His research is currently focused on wireless
networks, sensor networks, cyberphysical systems, and the convergence of control,
communication and computation.
Kumar is a member of the National Academy of Engineering of the USA, and the Academy
of Sciences of the Developing World. He was awarded an honorary doctorate by the
Swiss Federal Institute of Technology (Eidgenossische Technische Hochschule) in
Zurich. He received the IEEE Field Award for Control Systems, the Donald P. Eckman
Award of the American Automatic Control Council, the Fred W. Ellersick Prize of
the IEEE Communications Society, and the Outstanding Contribution Award of ACM
SIGMOBILE. He is a Fellow of IEEE. He was a Guest Chair Professor and Leader of
the Guest Chair Professor Group on Wireless Communication and Networking at
Tsinghua University, Beijing, China. He is an Honorary Professor at IIT Hyderabad.
He was awarded the Distinguished Alumnus Award from IIT Madras, the Alumni
Achievement Award from Washington University in St. Louis, and the Daniel C.
Drucker Eminent Faculty Award from the College of Engineering at the University of
CPCC Distinguished Seminar by John G. Proakis
Title: Digital Communication Techniques for Underwater Acoustic Channels
Date: Oct. 1, 2012, Mon.
Time: 11:00 AM
Venue: EH 2430
Underwater acoustic channels are generally characterized as randomly time-varying multipath channels. In this presentation, the characteristics of these channels are described in terms of their time-varying impulse response, time dispersion, frequency dispersion, path loss and additive noise. Then, the design of modulation/demodulation and coding/decoding techniques are considered, including single carrier and multicarrier transmission, turbo coding/decoding, and equalization for intersymbol interference. The performance of these techniques are assessed from the viewpoint of bandwidth efficiency and signal processing requirements.
John G. Proakis (S'58-M'62-F'84-LF'99) received the BSEE from the University of Cincinnati in 1959, the MSEE from MIT in 1961 and the Ph.D. from Harvard University in 1967. He is an Adjunct Professor at the University of California at San Diego and a Professor Emeritus at Northeastern University. He was a faculty member at Northeastern University from 1969 through 1998 and held the following academic positions: Associate Professor of Electrical Engineering, 1969-1976; Professor of Electrical Engineering, 1976-1998; Associate Dean of the College of Engineering and Director of the Graduate School of Engineering, 1982-1984; Interim Dean of the College of Engineering, 1992-1993; Chairman of the Department of Electrical and Computer Engineering, 1984-1997. Prior to joining Northeastern University, he worked at GTE Laboratories and the MIT Lincoln Laboratory.
His professional experience and interests are in the general areas of digital communications and digital signal processing. He is the co-author of the following books: Digital Communications (New York: McGraw-Hill, 2008, fifth edition), Introduction to Digital Signal Processing (Upper Saddle River: Prentice Hall, 2007, fourth edition); Digital Signal Processing Laboratory (Englewood Cliffs: Prentice Hall, 1991); Advanced Digital Signal Processing (New York: Macmillan, 1992); Algorithms for Statistical Signal Processing(Upper Saddle River: Prentice Hall, 2002);Discrete-Time Processing of Speech Signals (New York: Macmillan, 1992, IEEE Press, 2000); Communication Systems Engineering, (Upper Saddle River: Prentice Hall, 2002, second edition); Digital Signal Processing Using MATLAB V.4 (Boston: Brooks/Cole-Thomson Learning, 2007, second edition); Contemporary Communication Systems Using MATLAB (Boston: Brooks/Cole-Thomson Learning, 2004, second edition); Fundamentals of Communication Systems (Upper Saddle River: Prentice Hall , 2005)
CPCC Distinguished Seminar by Vahid Tarokh
Title: Fundamentals, Regulatory Issues, and the Future of Cognitive Radio Networks
Date: Feb. 24, 2012, Fri.
Time: 11:00 AM
Venue: Donald Bren Hall (DBH 6011)
I will discuss the current regulatory issues for opportunistic transmission, and the future networks based on these concepts. I will argue that the current regulations are very conservative. Then I will overview limits of cognitive transmission, and discuss that they may be hard to achieve in some scenarios. Finally, I will speculate (based on these facts) about the future of cognitive Radio networks.
Vahid Tarokh was an associate professor at the Department of Electrical Engineering and Computer Sciences (EECS) at MIT until 2002 . In June 2002 , he joined Harvard University, where he is a Perkins Professor of Applied Mathematics and a Hammond Vinton Hayes Senior Fellow of Electrical Engineering. He is the recipient of a number of awards and holds 2 honorary degrees.
CPCC Seminar by Khaled Salama
Title: The Memristor: An Elusive Device
Date: Feb. 23, 2012, Thu..
Time: 11:00 AM
Venue: CALIT2 room 3008
The memristor (M) is considered to be the fourth two-terminal passive element in electronics, alongside the resistor (R), the capacitor (C), and the inductor (L). Its existence was postulated in 1971, but its first implementation was reported in 2008. Where was it hiding all that time and what can we do with it? Come and learn how the memristor completes the roster of electronic devices much like a missing particle that physicists seek to complete their tableaus. The future of memristors is being modeled today at KAUST.
Dr. Salama received his Bachelor's degree with honors from the Electronics and Communications Department at Cairo University in Egypt in 1997, and his Master's and Doctorate degrees from the Electrical Engineering Department at Stanford University in the United States, in 2000 and 2005 respectively. He was an assistant Professor at RPI between 2005 and 2009. He joined KAUST in January 2009 and was the founding program chair till August 2011. His work on CMOS sensors for molecular detection has been funded by the National Institutes of Health (NIH) and the Defense Advanced Research Projects Agency (DARPA), awarded the Stanford-Berkeley Innovators Challenge Award in biological sciences and was acquired by Lumina Inc. He is the author of 90 papers and 8 patents on low-power mixed-signal circuits for intelligent fully integrated sensors and nonlinear electronics specially memristor devices. He is a senior member of IEEE.
CPCC Seminar by Itsik Bergel
Title: THE SPECTRAL EFFICIENCY OF CSMA AD-HOC NETWORKS
Date: Feb. 22, 2012, Wed.
Time: 11:00 AM
Venue: Calit2 3008
Wireless ad hoc networks (WANETs) allow users to communicate, sharing the same wireless channel, without the need of any infrastructure. The performance of wireless ad-hoc networks (WANET) is mainly limited by its self-interference. The talk will focus on the performance of WANETs applying slotted carrier sense multiple access (CSMA) mechanism and possibly utilizing also directional antennas. The CSMA protocol is based on RTS/CTS messages, which allow each node to evaluate the amount of interference that it will cause to other active nodes, and provide a powerful tool for network coordination.
Our analysis gives simple expressions for the network area spectral efficiency (ASE). The presented ASE expressions allow an evaluation of the optimal system parameters, and give insight on the behavior of the ASE as a function of the various system parameters. In particular we show that the ASE of a CSMA WANET is well approximated by the ASE of an optimized ALOHA WANET, multiplied by the exponent of the network back-off probability. We also show that if the network has a maximal delay constraint then the ASE grows linearly with the allowed delay.
Itsik Bergel was born in Beer-Sheva, Israel, in 1971. He received the B.Sc. degree in electrical engineering and the B.Sc. degree in physics from Ben Gurion University, Beer-Sheva, Israel, in 1993 and 1994, respectively, and the M.Sc. degree and Ph.D. in electrical engineering from the University of Tel Aviv, Tel Aviv, Israel, in 2000 and 2005 respectively. In 2005 he did a postdoc research at the Dipartimento di Elettronica of Politecnico di Torino. He currently is a lecturer at the School of Engineering, Bar-Ilan University, Ramat-Gan, Israel. His research spans various aspects of communications theory, including add-hoc networks, DSL systems, UWB communications and capacity evaluations of non-coherent channels.
CPCC Distinguished Seminar by Ali H. Sayed
Title: BIO-INSPIRED COGNITION AND DIFFUSION ADAPTATION OVER NETWORKS
Date: Feb. 14, 2012, Tue.
Time: 10:00 - 11:00 AM
Venue: EH 2430
Complex patterns of behavior are common in many biological networks, where no single agent is in command and yet forms of decentralized intelligence are evident. Examples include fish joining together in schools, birds flying in formation, bees swarming towards a new hive, and bacteria diffusing towards a nutrient source. While each individual agent in these biological networks is not capable of complex behavior, it is the combined coordination among multiple agents that leads to the manifestation of sophisticated order at the network level. The study of these phenomena opens up opportunities for collaborative research across several domains including economics, life sciences, biology, and information processing, in order to address and clarify several relevant questions such as: (a) how and why organized behavior arises at the group level from interactions among agents without central control? (b) What communication topologies enable the emergence of order at the higher level from interactions at the lower level? (c) How is information quantized during the diffusion of knowledge through the network? And (d) how does mobility influence the learning abilities of the agents and the network. Several disciplines are concerned in elucidating different aspects of these questions including evolutionary biology, animal behavior studies, physical biology, and even computer graphics. In the realm of signal processing, these questions motivate the need to study and develop decentralized strategies for information processing that are able to endow networks with real-time adaptation and learning abilities. This presentation examines several patterns of decentralized intelligence in biological networks, and describes diffusion adaptation and online learning strategies that our research group has developed in recent years to model and reproduce these kinds of behavior.
Ali H. Sayed is Professor of Electrical Engineering at the University of California, Los Angeles, and Principal Investigator of the UCLA Adaptive Systems Laboratory (www.ee.ucla.edu/asl ). He has published widely in the areas of adaptation and learning with over 350 articles and 5 books. His research interests span several fields including adaptation and learning, adaptive and cognitive networks,biological networks, cooperative behavior, distributed processing, and statistical signal processing.
CPCC Seminar by Tara Javidi
Title: Active Sequential Hypothesis Testing
Date: Dec. 1, 2011, Thu.
Time: 1:00 - 2:00 PM
Venue: EH 2430 (Colloquium room)
Active sequential hypothesis testing problem arises in a broad spectrum of applications in cognition, communications, design of experiments, and sensor management. In all of these applications, a decision maker is responsible to take actions dynamically so as to enhance information about an underlying phenomena of interest in a speedy manner while accounting for the cost of communication, sensing, or data collection. In particular, due to the sequential nature of the problem, the decision maker relies on his current information state to constantly (re-)evaluate the trade-off between the precision and the cost of various actions. In this work, we first discuss active sequential hypothesis testing as a partially observable Markov decision problem. In particular, we provide a brief survey of the design of experiment literature and the dynamic programming interpretation of information utility introduced by De Groot. Using Blackwell ordering, we, then, connect this stochastic control theoretic notion of information utility to the concept of stochastic degradation and uncertainty reduction in information theory. Finally, we discuss the dynamics and expected drift of log-likelihood, entropy, and probability of error as well as their connection to Kullback-Leibler divergence and mutual information in order to approximate the optimal value function (i.e. the solutions to the DP). We then utilize these value function approximations (lower bounds) to provide simple sequential test strategies (heuristics) whose performance is numerically compared to the optimal policies. Finally, we prove the asymptotic optimality of one class of these heuristic test strategies and, as a special case, recover Burnashev's coding scheme in the context of variable-length block coding over memoryless channels with feedback. Time permitting, we will compare and contrast our approach with recent results in Bayesian active learning literature. This is joint work with Mohammad Naghshvar and Ofer Shayevitz.
Tara Javidi studied electrical engineering at Sharif University of Technology, Tehran, Iran from 1992 to 1996. She received the MS degrees in electrical engineering (systems), and in applied mathematics (stochastics) from the University of Michigan, Ann Arbor, in 1998 and 1999, respectively. She received her Ph.D. in electrical engineering and computer science from the University of Michigan, Ann Arbor, in 2002. From 2002 to 2004, she was an assistant professor at the Electrical Engineering Department, University of Washington, Seattle. She joined University of California, San Diego, in 2005, where she is currently an associate professor of electrical and computer engineering. Tara Javidi was a Barbour Scholar during 1999-2000 academic year and received an NSF CAREER Award in 2004. Her research interests are in communication networks, stochastic resource allocation, stochastic control theory, and wireless communications.
CPCC Seminar by Mohamed-Slim Alouini
Title: Novel Generic Formulas and Relations for the Ergodic Capacity and Average Bit Error Rate over Generalized Fading Channels
Date: Sept. 9, 2011, Fri.
Time: 11:00 AM
Venue: Bren Hall (DBH) 3011
Analysis of the average binary error probabilities (ABEP) and ergodic capacity (EC) of wireless communications systems over generalized fading channels have been considered separately in the past. This talk introduces a novel moment generating function (MGF)-based unified approach for the exact computation of the ABEP and EC of single and multiple link communication with maximal ratio combining. This approach leads to a generic unified performance expression that can be easily calculated and that is applicable to a wide variety of fading scenarios. The talk introduces also a new analytical connection between the EC and the ABEP of binary modulation schemes. In particular formulas to obtain the EC from the ABEP and vice versa are proposed. Analytical and numerical examples are provided to illustrate the mathematical formalism for a variety of fading conditions.
Mohamed-Slim Alouini was born in Tunis, Tunisia. He received the Ph.D. degree in electrical engineering from the California Institute of Technology (Caltech), Pasadena, CA, USA, in 1998. He was with the department of Electrical and Computer Engineering of the University of Minnesota, Minneapolis, MN, USA, then with the Electrical and Computer Engineering Program at the Texas A&M University at Qatar, Education City, Doha, Qatar.
Since June 2009, he has been a Professor of Electrical Engineering in the Division of Physical Sciences and Engineering at KAUST, Saudi Arabia, where his current research interests include the design and performance analysis of wireless communication systems.
Title: CPCC Networkshop
On August 29, CPCC held an internal workshop on networking. CPCC researchers presented their work and discussed future possible collaborations.
Monday August 29
||Ali Behbahani "Linear Decentralized Estimation of Correlatd Data for Wireless Sensor Networks"
Jie Chen "On the Achievable Sum Rate of Multiterminal Source Coding for a Remote Gaussian Vector Source"
Feng Jiang "Phase-Only Analog Encoding for a Multi-Antenna Fusion Center"
Roberto Pagliari "Programming and Deployment of Wireless Sensor Networks"
||Furong Huang "Concurrent Load Balancing in Distributed Systems with Partial Information
Pegah Sattari "Network Coding for Inference Problems"
Maciej Kurant "Walking on a Graph with a Magnifying Glass: Stratified Sampling via Weighted Random Walks"
|4:15-5:00||Discussion, future directions, collaborations, etc.|
CPCC Seminar by Azadeh Vosoughi
Title: Wireless Channel Uncertainty in Relay-Assisted Communication and Distributed Detection Systems
Date: July 20, 2011, Wed.
Time: 11 AM
Venue: Engineering Hall 2430
One of the main challenges in wireless communications is coping with channel uncertainty. Dealing with this uncertainty, and the limitations it imposes, is tightly related to the specific system and its application. In this talk, we consider two systems, namely a wireless bi-directional relay-assisted communication system and a wireless distributed detection system. We study the impacts of channel uncertainty on the performance limits of these two systems and investigate optimal transceiver designs that minimize these impacts.
For the bi-directional relay-assisted communications we consider a training-based system, in which receivers learn the channels via employing dedicated pilot symbols. Assuming Gaussian inputs and block Rayleigh fading channel model, we study the trade-off between the accuracy and the bandwidth/energy costs of channel estimation and explore optimal transmit resource allocation, subject to network power constraint. We consider Cramer-Rao lower bound for channel estimation, sum-rate and outage probability bounds as the performance metrics.
Next, we discuss the effects of channel uncertainty on the design and performance of a wireless distributed detection system that is tasked with solving a binary hypothesis testing problem. We consider systems with training-based and blind channel estimation and coherent/non-coherent receptions. We investigate the optimal data fusion rules that maximize the overall system detection reliability and error exponent. Furthermore, we present and compare several detection and data fusion designs that exploit diversity to combat channel uncertainty and enhance system performance.
Azadeh Vosoughi is Wilmot Assistant Professor in the Department of Electrical and Computer Engineering at the University of Rochester. She received her BS degree from Sharif University of Technology, Tehran, Iran, in 1997, her MS degree from Worcester Polytechnic Institute, Worcester, MA, in 2001, and her PhD degree from Cornell University, Ithaca, NY, in 2006, all in Electrical Engineering. Her research interests lie in the areas of wireless relay-assisted communications, distributed detection and estimation, and distributed source coding and compression. She was the recipient of the Furth award in 2006 and was appointed as Wilmot Assistant Professor in 2009 at the University of Rochester. Dr. Vosoughi received the NSF CAREER award in 2011 for her research on the integration of signal processing and communications for distributed detection systems.
CPCC Distinguished Seminar by Ramesh Rao
Title: Enabling Citizen Science to Enhance and Transform Health
Date: April 22, 2011, Fri.
Time: 11 AM
Venue: DBH 6011
The dramatic spread in the use, along with significant increases in speed and efficiency, of broadband Internet and wireless devices in recent years has produced an excellent platform for the development of novel approaches to improve health through applications using emerging information technology, telecom, and other technology advances. These new technologies have the potential to advance the science and body of medical knowledge, as well as improve public and personal health across all types of medical conditions including chronic diseases (such as cardiovascular disease and diabetes/metabolic syndrome), trauma, and cancer. The utility of cutting-edge technologies in healthcare is just beginning to be explored.
The wireless devices and services in wide use today are packed with ample sensing, processing, storage and communication capabilities. With adaptation and augmentation, these systems can be transformed into tools for the preservation of health, rapid intervention for acute care and long-term management of chronic conditions, as well as other medical applications. The personal nature of these devices makes it possible to connect one (or more) body sensors for persistent gathering of vital signs to enable a new generation of diagnostics and interventions. These unobtrusive, wirelessly connected devices will play a critical role in the translation of epigenetic understanding in support of personal health. Calit2 is engaged in multiple projects related to these possibilities, and others, which bridge emerging technologies with healthcare delivery, knowledge, research, and outcomes. Working with local, regional, national, and international partners, Calit2 brings together faculty, clinical, student and staff researchers with academic, industry, community, and government collaborators to form multidisciplinary teams to prototype systems of emerging, transformational and disruptive technologies.
We are currently engaged in several projects which investigate the power of information technology to enhance, even transform, healthcare resources, knowledge bases, and outcomes utilizing Web 2.0 technologies. These include efforts to develop decision support tools, wireless patient and population health interventions, integrative databases that support these operations, as well as personal health information exchange, clinical trials, and more. New models are being created for population-specific health information sharing and development, resulting in platforms and ontologies which are not only the best possible implementations, but also the most responsive to the wide-ranging needs of the community at large (patients, healthcare providers, and medical researchers, alike). We are currently in early stages of creating a scalable effort at tracking, organizing and analyzing biometric data, especially metrics pertaining to the heart. Heart rate variability (HRV) is a measure of the beat-to-beat interval. It has become a noninvasive tool for accessing the activities of the autonomic nervous system. The fact that HRV can be easily derived makes it a promising marker for the study of human physiological response. We will share a few _early_ experiences in engaging a group of lay citizen scientists who are involved in gathering, sharing and analyzing physiological data to enhance personal understanding and also developing new data informed practices.
Ramesh Rao is the director of the University of California, San Diego division of the California Institute for Telecommunications and Information Technology (Calit2). He holds the Qualcomm Endowed Chair in Telecommunications and Information Technologies in the department of Electrical and Computer Engineering at UC San Diego, where he has been a faculty member since 1984. Previous to Calit2, he was the director of UCSD's Center for Wireless Communications. Prof. Rao is involved on a day-to-day basis with a wide variety of interdisciplinary and collaborative research initiatives, leading several major projects at Calit2. He has been a lead investigator on dozens of major federal-, state-, foundation-, defense-, and industry-funded grants and has authored more than 225 technical papers.
For his leadership in wireless communications, Dr. Rao was named an IEEE Fellow. He has been a member of the Board of Governors of the IEEE Information Theory Society. He is a Senior Fellow of the California Council on Science and Technology (CCST) and is the chair of the CCST's Personalized Health Information Technology Task Force ("pHIT"). He is a member of the Rady Children's Hospital and Health Center's Information Technology Task Force. He is also a member of the Health Authority of Abu Dhabi's Weqaya Advisory Task Force. In 2010, he received a Professional Gordon Engineering Leadership Award from UCSD's Gordon Engineering Leadership Center. He is on the Board of Directors of CommNexus San Diego and is the vice-president of the San Diego Indian American Society (SDIAS). He participates in many other technical, academic and industry organizations, boards, councils and committees. He earned his Ph.D. and M.S. in electrical engineering from the University of Maryland, College Park, MD.
About 100 people attended the CPCC Research Showcase
On March 9, CPCC held a research showcase in the Calit2 Building to share its accomplishments and present a look at future opportunities.
An audience of nearly 100 listened intently to researcher presentations, viewed posters and demonstrations, and shared their insights into the constantly evolving field of communications.
School of engineering Interim Dean Dimitri Papamoschou welcomed the guests, followed by John Hemminger, vice chancellor or research, who discussed the CPCC's role at UCI. Other speakers included Calit2 Irvine director G.P. Li and CPCC director Hamid Jafarkhani.
Three CPCC-affiliated professors made research presentations: Payam Heydari discussed circuit and hardware design; Lee Swindlehurst offered a look into communications systems; and Homayoun Yousefi'zadeh shared the center's efforts in networking.
The research showcase was co-sponsored and supported by Calit2.
CPCC Research Showcase
Join us Wednesday, March 9 for activities showcasing the center's novel research. Explore some of the technologies in development and discover emerging opportunities for collaboration.
The event is free, but, Registration is required. Register
CPCC Distinguished Seminar by Vincent Poor
Title: Information and Inference in the Wireless Physical Layer
Date: January 14, 2011, Fri.
Time: 11:00 AM
Venue: DBH 6011
Wireless networking applications continue to motivate challenging problems in information theory, signal processing, and other fields. A salient feature of wireless networks is the close interaction between the physical layer and the other networking layers. This phenomenon is a result of the principal distinguishing features of wireless, namely mobility and the importance of physical properties (diffusion, interference, fading and radio geometry) in determining link characteristics. For example, the applications layer interacts considerably with the physical layer, as is well known through the importance of quality-of-service in wireless network design. This talk will explore briefly four research areas, primarily involving information theoretic or inferential problems, each of which is motivated by an applications-layer issue. In particular, the four applications of file transfer, inference, real-time multimedia transmission, and social networking, will be used to motivate consideration of four respective research problems involving the physical layer: physical layer security in data networks, distributed inference in sensor networks, finite-blocklength capacity in multimedia networks, and connectivity in small-world networks. Recent progress in each of these four research areas will be reviewed.
H. Vincent Poor is the Michael Henry Strater University Professor of Electrical Engineering at Princeton University, where he also Dean of the School of Engineering and Applied Science. His current research interests lie primarily in the area of wireless networking and related fields. Among his publications in these areas are the recent books Quickest Detection (Cambridge, 2009) and Information Theoretic Security (NOW, 2009). Dr. Poor is a member of the National Academy of Engineering, and is a Fellow of the IEEE, the American Academy of Arts & Sciences, and the Royal Academy of Engineering of the U.K. He has served as President of the IEEE Information Theory Society, and as Editor-in-Chief of the IEEE Transactions on Information Theory. In 2005, he received the IEEE Education Medal. Recent recognition of this work includes the 2009 Edwin Howard Armstrong Achievement Award of the IEEE Communications Society, the 2010 IET Ambrose Fleming Medal for Achievement in Communications, and the 2011 IEEE Eric E. Sumner Award.
CPCC Student Seminar Series Launched
CPCC launched a student seminar series to provide a forum for graduate students to disseminate their research. In this series, CPCC graduate students and sometimes faculty present their research results to fellow researchers, talk about their open problems, and possibly find topics of mutual interest to collaborate on. For the first time, the series is run by current CPCC graduate students during the 2010-2011 academic year. Currently, the series covers topics in communications, networking, and information theory. In future, the topics will be extended to also cover circuit design. The talks take place Tuesdays at 11:00-12:00 in Engineering Hall 2430 and are open to the public. Refreshments will be served at 10:50 AM. The schedule of the talks can be found in the seminar webpage.
CPCC members participated in IEEE Globecom 2010
The IEEE Globecom 2010 was held in Miami, FL, from Dec. 7 to Dec. 10. CPCC faculty members, Ender Ayanoglu, Syed Ali Jafar, Hamid Jafarkhani, and Lee Swindlehurst served as session chairs in the conference. CPCC students, Tiangao Gou, Jing Huang, Feng Jiang, Boyu Li, Feng Li, Liangbin Li, and Chenwei Wang participated and presented 7 papers collaboratively.
CPCC Distinguished Seminar by Bhaskar Rao
Tiltle: Insights into the Stable Recovery of Sparse Solutions
Date: June 9, 2010, Wed.
Time: 11 AM
Venue: Engineering Hall 2430
The problem of sparse signal recovery has received much attention recently with the development of compressed sensing. In this talk, we will examine the problem of stable recovery of sparse solutions in noisy environments. First we will briefly review algorithms for sparse signal recovery and discuss the connection between l1 minimization and support recovery of sparse signals to provide context. We then establish a connection between the sparse signal recovery problem and wireless communication models in network information theory. We will show that the stable recovery of a sparse solution with a single measurement vector (SMV) can be viewed as decoding competing users simultaneously transmitting messages through a Multiple Access Channel (MAC) at the same rate. With multiple measurement vectors (MMV), we relate the inverse problem to the wireless communication scenario with a Multiple-Input Multiple Output (MIMO) channel. In each case, based on the connection established between the two domains, we will leverage channel capacity results to shed light on the fundamental limits of any algorithm to stably recover sparse solutions in the presence of noise.
Bhaskar D. Rao received the B.Tech. degree in electronics and electrical communication engineering from the Indian Institute of Technology, Kharagpur, India, and the M.S. and Ph.D. degrees from the University of Southern California, Los Angeles, in 1981 and 1983, respectively. Since 1983, he has been with the University of California at San Diego, La Jolla, where he is currently a Professor with the Electrical and Computer Engineering Department. His interests are in the areas of digital signal processing, estimation theory, and optimization theory, with applications to digital communications, speech signal processing, and human-computer interactions.
He is the holder of the Ericsson endowed chair in Wireless Access Networks and is the Director of the Center for Wireless Communications. His research group has received several paper awards. Recently, a paper he co-authored with B. Song and R. Cruz received the 2008 Stephen O. Rice Prize Paper Award in the Field of Communications Systems and a paper he co-authored with S. Shivappa and M. Trivedi received the best paper award at AVSS 2008. " He was elected to the fellow grade in 2000 for his contributions in high resolution spectral estimation.
CPCC Fall 2009 Seminar Series Launched
CPCC is continuing its seminar series during the Fall quarter of 2009, with an emphasis on circuits and systems for communications. CPCC faculty, postdoctoral fellows, and graduate students are presenting their research results to fellow researchers. Sample topics to be presented are integrated circuits for millimeter applications, equalization techniques for optical communication, and architectures for error correcting coding. The seminars take place Mondays at 10 AM at 2430 Engineering Hall and are open to the public. Weekly announcements are emailed to the EECS graduate student and CPCC mailing lists. In order to receive the talk announcements, subscribe to the CPCC Mailing List or visit the CPCC Mailing List Archives to browse through past announcements.
CPCC Seminar Series Launched
CPCC launched a seminar series in order to provide a forum for dissemination of its research during the Winter quarter of 2009, extending into the Spring quarter of 2009. In this series, CPCC faculty, postdoctoral fellows, and graduate students are presenting their research results to fellow researchers. Currently the series covers topics in communication and information theory. This series will be extended into the 2009-2010 academic year and then it will cover networking and circuit design in addition to communication and information theory. The talks take place Mondays at 10 AM and are open to the public. In order to receive talk announcements, subscribe to the CPCC Mailing List or visit the CPCC Mailing List Archives to browse through past announcements.
2005 HSSoE Research Symposium CPCC Session
There is a research symposium organized every spring by the Henry Samueli School of Engineering at UC Irvine. The theme of the Symposium in 2005 was California: Prosperity Through Technology. One of the sessions during this symposium, titled Precursors of the Next Wave in Communications, was organized by CPCC. The session took place May 23, 2005. After a Keynote Opening by Raouf Halim, Chief Executive Officer of Mindspeed Technologies, Inc. (a CPCC donor), five faculty associated with CPCC outlined their most recent research. Presentations used during the session, as well as its video, are available from the links on the right.
Presentation Slides (PPS 14MB)
2005 HSSoE CPCC Panel
UC Irvine The Henry Samueli School of Engineering organized its yearly Research Symposium in 2005 on May 23-24, 2005. Center for Pervasive Communications and Computing contributed a panel, titled Pervasive Communications: All the Time, Everywhere, held on May 23, 2005. The eight panelists, drawn from Southern California academic and industrial organizations, discussed the state and the future of the telecommunications industry during the panel. For a video of the panel as well as the Power Point presentations, follow the links on the right.
Presentation Slides (PPS 12MB)
CPCC Summer 2004 Research Presentation Day for Conexant, Mindspeed, and Skyworks Takes Place
CPCC held a Research Presentation Day for three of its donor companies Conexant Systems, Mindspeed Technologies and Skyworks Solutions on July 15, 2004. The event was organized in order to bring CPCC member and affiliate faculty together with researchers from the three companies and to discuss research interests of both sides. The day was part of a series of planned events to put a process in place so that CPCC and its donors can engage in close cooperative research. The first phase of this plan was a CPCC/Cal-(IT)2 Poster Presentation Day held on-site at the lobbies of the Newport Beach facilities of Conexant and Mindspeed on May 14, 2004. The Research Presentation Day of July 15, 2004 will be followed by a number of proposals from CPCC member and affiliate faculty, which will result in the determination of a number of CPCC Research Fellowships for the academic year 2004-2005.
CPCC/Cal-(IT)2 Poster Presentation Day for Local High-Technology Companies Takes Place
Graduate students from CPCC and Cal-(IT)2 presented their research in a poster presentation session held on-site at the Newport Beach lobbies of Conexant Systems and Mindspeed Technologies May 14, 2004. A total of 30 graduate students, 15 from UC Irvine and 15 from UC San Diego, displayed their research.
The goal of the event was to bring graduate student researchers in close contact with the technical teams from the companies. "It's not easy for our technical staff to get out of their offices and attend off-site research presentations," said Debbie Mountford, director of staffing and university relations at Conexant Systems. "We decided it was a great idea to bring the research to them and based on the reaction it appears to be the way to go."
H. Vincent Poor Gives Distinguished Speaker Talk
H. Vincent Poor, a worldwide known scholar, researcher, and educator in the fields of information theory, communications and signal processing visited UCI and gave a Distinguished Speaker talk on February 18, 2004. The event was co-sponsored by the UCI division of the California Institute for Telecommunications and Information Technology, The Henry Samueli School of Engineering, and the Center for Pervasive Communications and Computing. The talk was titled "Signal processing in communications: Issues and trends." In his talk, Professor Poor discussed a number of new areas in communications such as turbo processing, multiple-input multiple-output systems, cross-layer design, and quantum communications in a multiuser detection framework.
Presentation slides (PPS 1MB)
Digital Signal Processing Pioneer Visits CPCC
Professor Lawrence R. Rabiner, one of the pioneers of the field of digital signal processing, and a highly accomplished engineer, scientist, inventor, and research leader, visited the CPCC on February 13, 2003 and gave a presentation entitled "Telecom technology for the 21st century." In his talk, Professor Rabiner described the revolution that has taken place in telecommunications during the last decade and pointed to the new telecommunications network architecture that has arisen as a result of this big change. He outlined what the telecommunications network in the 21st century will look like, and gave demonstrations of new services that have already been built. Examples included a text-to-speech system that delivers the emotion in the text, a highly helpful customer care representative system based on speech recognition, and a travel agent software which employs speech recognition as well as facial expression on a 3-D model. Prior to assuming professor positions at Rutgers University and UCSB, Dr. Rabiner was most recently Vice President of Research at AT&T Laboratories where he managed a broad research program in communications, computing, and information sciences.
Presentation slides (PDF 6MB)
Inventor of TCM Visits CPCC
Dr. Gottfried Ungerboeck, inventor of the technique of Trellis Coded Modulation, visited the CPCC on December 9, 2002 and gave a presentation entitled "Coding with Euclidean-space signals: past, present and outlook." Dr. Ungerboeck, who is currently with Broadcom Corporation, is a well-known scientist and engineer, who has spent most of his career at the IBM Zurich Research Laboratory. While working on voiceband modems, he made the critical observation that it is possible to enlarge the signal constellation by a factor of two, code in the new signal space, and achieve a rate very close to channel capacity without increasing transmission bandwidth. The invention immediately made its way into voiceband modem standards, microwave transmission, and many other applications. The talk is an overview of the current state of coding and modulation.
Presentation slides (PDF 700KB)
Communication Theory Pioneer Visits CPCC
Dr. Marvin Simon, one of the pioneers of the field of communication theory, visited CPCC on October 28, 2002 and gave a talk titled "Advances in Performance Techniques for Wireless Communications." Dr. Simon is a Principal Scientist at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California. He has been a technology pioneer for the last 34 years and has performed research applied to the design of NASA's deep-space and near-earth missions. Dr. Simon is currently on a Research Leave in the Department of Electrical Engineering at the University of California, Los Angeles where he is responsible from forming research collaboration with academic institutions. Dr. Simon is currently working with the CPCC faculty member Prof. Hamid Jafarkhani on extending the techniques presented in his talk to the analysis of error performance of space-time codes in fading channels. Dr. Jafarkhani is one of the inventors of space-time codes, invented three years ago and have already been adopted by next generation cellular network standards WCDMA and cdma2000.
In his talk, Dr. Simon illustrated techniques that enable a unified analysis methodology for different fading channel models and yield closed form solutions. Until recently, when Dr. Simon and his colleague Prof. Slim-Alouni invented the new closed form techniques, system design for fading channels was mostly based on simulations. In communication engineering, closed form solutions are preferable to simulations since they provide substantially more insight into system behavior. Most of the techniques described by Dr. Simon in his talk can be found in his two books Digital Communication Over Fading Channels: A Unified Approach to Performance Analysis (John Wiley and Sons, 2000) and Probability Distributions Involving Gaussian Random Variables: A Handbook for Engineers and Scientists (Kluwer Academic Publishers, 2002).