Research in electrical and computer engineering at the University of Illinois at Urbana-Champaign encompasses a broad spectrum of areas which reflect the wide range of interest and expertise of the faculty, as illustrated by the number and diversity of the research projects denoted in the following pages. Almost all of the faculty members in the department are engaged in research and many do research in interdisciplinary programs and hold joint appointments in other departments and interdisciplinary laboratories. More than 450 graduate students and many undergraduates assist in this research effort.
Support for this research is provided by contracts and grants from several agencies of the federal government as well as from industrial sources. Other departments and laboratories in which the department's faculty hold affiliate status and are engaged in interdisciplinary research include Computer Science, General Engineering, Materials Science and Engineering, Music, Nuclear Engineering, Physics, Biophysics and Computational Biology, the Coordinated Science Laboratory, the Materials Research Laboratory, the Microelectronics Laboratory, and the Beckman Institute for Advanced Science and Technology.
Path Planning for Robot Navigation
N. Ahuja*
Rockwell International
This project concerns efficient generation of object representations
from multiple perspectives. We are developing algorithms to generate
octree representation of an object from its planar projections. We use
the known representation of obstacles to plan efficient motion
trajectory to move an object from one location to another.
Image Segmentation
N. Ahuja,* R. Dugad
Eastman Kodak Co.
The goal of this project is to segment an image, or an image sequence,
into its constituent regions such that each region is characterized by
homogeneity of a three-dimensional property. Currently, we are
developing segmentation algorithms that use uniformity of three-
dimensional surface texture and three-dimensional object motion as
homogeneity criteria.
Sensory Feedback and Control of Legged Locomotion--Biological
Simulation and Robotic Implementation
N. Ahuja,* F. Delcomyn,* M. Nelson,* J. Hart, J. Cocatre-Zilgien, J.
Payne
National Science Foundation, INT 92-15265
This project is aimed at the design of a six-legged robot that is able
to traverse irregular terrain mimicking the locomotion capabilities of
insects. The completed robot will have a structure similar to that of
an insect. In the model, each leg has three degrees of freedom, and
the orientations and separations of joints are made to parallel the
anatomy of the insect's legs. The robot leg movements are powered
pneumatically (using compressed air) in an attempt to achieve the
strength and compliance of muscle. Various robot design parameters are
being obtained through experimental studies of insect locomotion. The
planned controller of the robot is based on central pattern generators
thought to coordinate the leg movements in insects.
Multiscale Image Structure Detection
N. Ahuja,* P. Bajcsy, K. Ratakonda
National Science Foundation, IRI 93-19038
The objectives of this research are analysis, development, real-time
implementation, and real-world application of a new image transform.
The transform is aimed at multiscale, low-level image segmentation,
i.e., extraction and representation of image structure at all
geometric and photometric scales present in an image. Specifically,
the transform detects contours and skeletons of image regions, and
identifies the cross-scale relationships among these. The scales
present are a priori unknown and must be identified automatically.
Application of the transform to a range of problems is investigated.
Image Matching and Interpretation
N. Ahuja,* P. Bajcsy
ATR International
This project is aimed at the interpretation of moving, nonrigid
surfaces carrying little or limited detail, with applications to
virtual space teleconferencing. The objectives include delineation of
moving parts of a scene, active selection of viewpoints and data
acquisition, and integration of focus, shading, and silhouette
information for functionality under a range of environmental
conditions.
Image Analysis, Perception, and Synthesis of Dynamic Scenes
N. Ahuja,* T. S. Huang, G. Lintern, J. Patel, T. Courtney,
Defense Advanced Research Projects Agency, N00014-93-I-1167
This project concerns (1) analysis of images of dynamic scenes, (2)
analysis-guided synthesis, and (3) perceptual evaluation of
synthesized image sequences with emphasis on computational speed, each
aimed at the 3-D motion and structure characteristics relevant to
navigation. The first part is concerned with integrated analysis and
estimation of 3-D motion and structure parameters from multiple image
cues or attributes, including those obtained during active acquisition
of image sequences and those extracted from the acquired image
sequence. Image synthesis is based on the new notion that the cues
that contributed the most to 3-D interpretation also would contribute
the most to perceptually realistic synthesis, thus suggesting an
approach to analysis-guided synthesis, compression, and visualization.
The perceptual evaluation tests the efficacy of analysis-guided
synthesis.
Hierarchical Image Representation, Analysis, and Manipulation
N. Ahuja,* R. Dugad, M. Singh, S. Yoon, M. Yang
U.S. Office of Naval Research, N00014-96-1-0502
This research is aimed at high-performance image representation,
manipulation, and analysis. The use of image representation is
investigated for three-dimensional scene estimation and communication
of multidimensional and multivariate images (e.g., magnetic resonance
images and color images). New representations are developed for image
texture and perceptual groupings. Finally, multiscale representations
are used to develop a toolset for browsing of image databases, image
editing, and composition.
Neural Control, Active Sensing, and Sensorimotor Integration in
Hexapod Robots
N. Ahuja,* M. Nelson,* J. Hart, J. Ma
U.S. Office of Naval Research, N00014-96-1-0657
The goal of this research project is to design, construct, and
evaluate integrated active sensing and motor control systems for
legged robots using insights provided by insect neurobiology. In
particular, we plan to develop and test neurally inspired robotic
control systems that acquire, process, and integrate sensory
information from two distinct sensory modalities in order to carry out
visually guided target tracking and target approach behavior in
environments that may include obstacles and irregular terrain. The two
sensory systems we will consider are: (1) tactile, proprioceptive, and
stress signals from leg sense organs and (2) visual signals from the
eyes, along with relevant proprioceptive signals related to head and
body position.
Augmented Reality
N. Ahuja,* A. Castano
U.S. Army Research Laboratory, DAAL01-96-2-0003F
The objective of this project is to develop computer vision-based
approaches to augmentation of 3-D displays of real scenes. Displays
may select a subset of original image features or add new ones to
enhance the perception of the scene structure and dynamics. The
displays may also overlay on the images information from a variety of
sources to increase the situational awareness.
Process Technology and Its Implications for Inspection and
Manufacturing of Ceramic Multichip Modules
J. Lewis,* S. Hutchinson*
National Science Foundation, DDM 93-13126
The objective of this research is to improve the quality,
reproducibility, and speed of ceramic-based multichip module
manufacturing. An interdisciplinary effort will focus on materials and
processing issues and on automated visual inspection of tape-cast
ceramic layers. This will be addressed by an experimental program that
(1) characterizes the rheological properties as a function of
suspension composition and time and (2) determines the microstructural
variations within the layers. Insights gained from this program will
be used to derive statistical models for defect occurrence, which will
then drive the inspection process. The result will be improved
dimensional control, reproducibility, and automated visual inspection
of tape-cast sheets.
Visual Servo Control of Robotic Systems
S. Hutchinson,* R. Kelly (CICESE)
National Science Foundation, IRI 96-13737
This project involves joint work with researchers at CICESE in
Ensenada, Mexico. The goal of this collaboration is to expand our own
research in the area of visual servo control of robotic manipulators
so that the previously neglected aspect of robot dynamics will be
taken into consideration. We currently have an active research program
in visual servo control at the University of Illinois at Urbana-
Champaign (UIUC). We will expand our current research efforts by
capitalizing on the dynamics and control expertise of the researchers
at CICESE. Our current research in intelligent control and in
optimizing the performance of visual servo systems will directly
benefit from these efforts.
Control of Underactuated Mechanical Systems
M. W. Spong*
National Science Foundation, CMS-9402229, CMS-9712170
This project concerns the nonlinear control of underactuated
mechanical systems. This class of systems is quite broad and
encompasses flexible structures of all kinds including flexible link
robots, flexible joint robots, as well as robot models that include
actuator dynamics, and many of the classical control problems like the
ball-and-beam and cart-pole systems. Techniques such as partial
feedback linearization, singular perturbations, and passivity methods
are being applied for global and semiglobal stabilization of these
systems.
Integration of Machine Learning and Sensor-based Control in
Intelligent Robotic Systems
M. W. Spong,* J. DeJong (Comput. Sci.), S. Hutchinson,
National Science Foundation, IRI 92-16428; Electric Power Research
Institute, RP 8030-14
This project concerns the integration of machine learning and sensor-
based control in intelligent robotic systems. The research combines
techniques of explanation-based control with robust and adaptive
nonlinear control, computer vision, and robot motion planning. We wish
to go beyond the strict hierarchical control architectures typi-cally
used in robotic systems by integrating modeling, dy-namics, and
control at all levels of intelligence. Our ultimate goal is to combine
analytical techniques of nonlinear dynamics and control with
artificial intelligence into a single new paradigm, in which symbolic
reasoning holds an equal place with differential equation based
modeling and control.
Adaptive Control of Underactuated Mechanical Systems
M. W. Spong,* R. Lozano, B. Brogliato, R. Ortega
National Science Foundation, INT-9415757
This project fundamental issues in the adaptive control of
underactuated mechanical systems. This class of systems encompasses
both holonomic and nonholonomic systems such as balancing and walking
robots, space robots, flexible link robots, and flexible joint robots,
as well as robot models that include actuator dynamics, and many of
the classical control problems like the ball-and-beam and cart-pole
systems. Techniques such as partial feedback linearization, singular
perturbations, and passivity-based methods are being applied for
global and semiglobal stabilization of these systems.
Processing of Gallium Nitride and Related Compounds
I. Adesida,* A. Schmitz
Samsung
This program consists of the development of viable processing methods
for gallium nitride and related compounds. A systematic study of
etching techniques, ohmic contact formation, and other metallizations
will be conducted.
Advanced Semiconductor Structures and Devices for the Next Generation
of Wireless Systems
I. Adesida,* C. Lee
Georgia Institute of Technology/National Science Foundation, ECS 96-
33535
This project is a collaboration with the Georgia Institute of
Technology and TRW, Inc. on the interplay between heterostructure
materials grown by solid-source molecular beam epitaxy and advanced
devices. Specific study of pseudomorphic InAlAs/InAsP/InP field effect
transistors for high-speed, high-power applications is addressed in
this research.
Silicon Heterojunction Terabit Electronics
I. Adesida,* J. Tucker,* K. Ismail,* C. L. Wang
Defense Advanced Research Projects Agency, N66001-97-1-8906
This is an exploratory research project on advancing the performance
of silicon-based field effect transistors. The utilization of shallow
metal silicide Schottky source/drain and the use of strained Si/SiGe
materials are two of the pathways being explored to realize ultrasmall
(~ 25 nm) channel silicon-based heterojunction electronics capable of
low power and terabit operation. This is a collaborative effort with
IBM Corp. and Yale University.
Silicon-Germanium Modulation-doped Field Effect Transistors
I. Adesida,* K. Ismail*
National Science Foundation, ECS 97-10418
This collaborative program with IBM Corp. is to significantly advance
the growth and fabrication technologies for SiGe/Si modulation-doped
field effect transistors (MODFETs) needed for low-power, high-speed
microwave and digital applications. Specific goals are to study the
physics of short gate-length p-type, n-type, and complementary MODFETs
and to demonstrate simple circuits.
Gallium Nitride Optoelectronics
I. Adesida,* A. Ping, R. Zhou
National Science Foundation, ECS 95-21671
This project focuses on experimental issues for the fabrication of
novel optoelectronic devices and circuits in gallium nitride and
related materials. UV detectors, field effect transistors, and
heterojunction bipolar transistors will be investigated. Methods for
integrating these devices will also be explored.
Optoelectronic Integrated Receiver Circuits
I. Adesida,* A. Mahajan, P. Fay, G. Cueva
NSF Center for Compound Semiconductor Microelectronics
This program consists of fabricating and characterizing high-speed
optical and electronic devices. Novel advanced microelectronic
processes are used to fabricate MSM photodetectors and modulation-
doped transistors with submicrometer critical dimensions in various
III-V compound semiconductors. The final objective of this work is the
realization of wide bandwidth (>20 GHz) integrated optoelectronic
receiver circuits.
High-Speed Metal-Semiconductor-Metal Photodetectors
I. Adesida,* G. Cueva
DARPA Center for Optoelectronics Science and Technology
This program is an experimental investigation on the design and
characterization of high-speed metal-semiconductor-metal (MSM)
photodetectors working at long wavelengths (1.3 and 1.55 m). The
influence of nanometer-scale metal gratings and variations in the
photon-absorbing layer on the speed will be investigated. The utility
of transparent conductors as the electrodes will also be investigated.
Electronic and Transport Properties of Ultralow-dimensional
Semiconductor Structures
I. Adesida,* J.-P. Leburton,* A. Kulier
Joint Services Electronics Program, N00014-96-J-1270
Ultralow-dimensional structures, such as quantum wires or quantum
dots, characterized by transverse dimensions below 100 nm may
constitute the next generation of very sophisticated semiconductor
devices. This research is aimed at investigating the potential of
these artificial systems for VLSI and high-speed applications. This
effort involves the fabrication and characteristics of low-dimensional
structures as well as basic studies and modeling of their electronic
and transport properties.
Scanning Tunneling Microscope-based Nanolithography
I. Adesida,* S. Bishop,* P. Bohn,* K. Y. Cheng,* K. Hess,* J. W.
Lyding,* M. Nayfeh,* J. R. Tucker*
U.S. Office of Naval Research University Research Initiative, N00014-
92-J-1519
Scanning tunneling microscopy (STM) is being developed as a
nanofabrication tool to extend electronic device fabrication into the
sub-0.1 regime. This University Research Initiative is combining STM
nanolithography with electron beam lithography, molecular beam
epitaxy, dry processing, and silicon and III-V device fabrication to
pursue this goal. To date, linewidths of 1 nm have been achieved on
silicon surfaces using a unique ultrahigh vacuum (UHV) STM system
constructed at the Beckman Institute. This capability is now being
applied to fabricate devices that are controlled by quantum size
effects.
Fabrication of Microminiature Devices and Micro-Electrical-Mechanical
Systems
I. Adesida, T. A. DeTemple, K-C. Hsieh, B. C. Wheeler;
University of Illinois Critical Research Initiative Program
Applications for micro-electrical-mechanical systems (MEMS) that are
being developed include low-cost microoptical mechanical switches for
telecommunications, mechanical devices for microsurgery, and masks for
biological molecule deposition. This project is aimed at high-force
and displacement devices, as well as using dissimilar materials and
creating 3-D utility from planar elements. One approach is to combine
wafer-scale and laser-material processing to join elements which
cannot be fabricated in the same process as silicon. Research in
silicon and laser-material processing is currently being developed to
solve the fundamental issues of MEMS.
Processes for GaN-based Laser Structures
I. Adesida,* C. Youtsey
Defense Advanced Research Projects Agency; CREE Research, Inc.
This project is to develop processes for the fabrication of GaN/AlGaN
laser structures. Various patterning schemes based on ion-assisted and
laser-assisted etching will be investigated for the formation of laser
facets.
Coherent Wavepacket Motion in Semiconductors
R. Giannetta,* I. Adesida,* A. Kulier
U.S. Army Research Office, DAAH-04-95-1-0618
This project seeks to understand temporal coherence in nanostructures
and to determine the physical constraints for coherent electronic
motion in future ultrahigh-speed devices. Both interferometric and
spectroscopic measurements will be used to probe electronic
wavepackets in fabricated GaAs/AlGaAs nanostructures.
Quantum Circuits at High Frequencies
R. Giannetta,* I. Adesida,* J. White,* P. Phillips*
University of Illinois Critical Research Initiative Program
This project involves using the combination of ultrafast laser and
electrooptic methods (terahertz spectroscopy) to probe the response of
mesoscopic devices at low temperatures. The goal is to understand
single electron dynamics at dc and terahertz frequencies.
Heterostructure Field Effect Transistors for Ultrahigh Frequency
Applications
I. Adesida,* A. Mahajan
Kopin Corp.
InGaP/InGaAs/GaAs pseudomorphic modulation-doped field effect
transistors are investigated for applications up to W band. Novel
fabrication technologies will be applied to fabricate short gate
length devices and to facilitate manufacturability. Various
heterostructure configurations will be investigated for high-power and
high-speed performance.
Engineering Services and Utilities for the Bondville Field Station
E. Kudeki,* S. Henson
National Oceanic and Atmospheric Administration,
Continuous operation of the FLATLAND ST (stratosphere-mesosphere)
radar administered by NOAA is maintained at the Bondville Field
Station. The FLATLAND radar, operating at a frequency of 50 MHz, has
been designed to investigate the dynamics of the atmosphere above a
plain area with insignificant orographical forcing. The routinely
measured reflectivity profiles and Doppler spectra are collected in a
NOAA database. Joint measurements with the Urbana Field Station MST
radar are performed to investigate the horizontal scale lengths of
atmospheric gravity waves and to follow the transit of weather fronts.
Radar Studies of the Equatorial Ionosphere
E. Kudeki,* E. Chapin, S. Bhattacharyya, J. Urbina
National Science Foundation, ATM 90-22400
The 50 MHz Jicamarca Radio Observatory located near Lima, Peru, is
used to investigate the structure and dynamics of the equatorial
ionosphere. In the mesosphere ionospheric D region, investigations aim
to resolve the internal structure of narrow echoing layers and
determine the relevant scattering/reflection mechanisms. In the higher
ionosphere, E- and F-region plasma drifts, instabilities, and
turbulence are under study. Current projects include efforts to
quantify the anisotropies of equatorial plasma turbulence, obtain
interferometric images of plasma irregularity structures, and measure
the component of ionospheric drifts in the geomagnetic field
direction. Major research effort is dedicated to the refinement of
radar techniques suitable for these studies.
Equatorial Middle Atmosphere Coupling and Dynamics Using the Jicamarca
Radar
E. Kudeki,* C. Fawcett
National Science Foundation, ATM 91-19923
This is a three-year project funded for stratospheric and mesospheric
wind and momentum flux deposition measurements using the 50 MHz radar
facilities at the Jicamarca Radio Observatory located near Lima, Peru.
The measurements are to be conducted during six 10-day campaigns
planned for the 1993-1995 period. The radar measurements will be used
to investigate the enegetics and coupling of various wave motions in
the equatorial middle atmosphere and their influence on the mean flow.
Engineering Services and Utilities for ST Radar Operation at the
Sidney Field Station
E. Kudeki,* S. Henson
National Science Foundation, SBC Utah State
This grant concerns the operation of an ST radar at the university's
Sidney Field Station. Tropospheric and stratospheric wind,
reflectivity, and aspect sensitivity measurements to be conducted with
the Sidney radar will complement similar measurements conducted by
similar radars operated at the Urbana Atmospheric Observatory and
Bondville Field Station. The three-radar network will be used in
correlative studies of atmospheric gravity wave propagation in the
troposphere and the lower stratosphere as well as phenomena associated
with the evolution and dynamics of weather fronts.
Logic Design Verification and Correction
I. N. Hajj,* A. Veneris
Joint Services Electronics Program, N00014-90-J-1270
This project considers the problem of design error detection in logic
design implementations. Techniques have been developed to detect and
automatically correct single and multiple design errors. The approach
relies on functional verification methods and test vector simulation
techniques for error location and correction. The method is also
applicable to fault diagnosis and design modification and
optimization.
Design Verification of VLSI Circuits
I. N. Hajj,* T. Chen, N. Lu
Semiconductor Research Corp.
The aim of this research is to develop numerical methods and computer
algorithms for design verification and testing of VLSI circuits at the
timing and logic levels. This work includes circuit extraction from
layout and automatic test generation for bridging faults for combined
voltage and JDDQ testing. Hierarchical and mixed-mode simulation
methods including interconnect and cross-talk effects are being
developed.
Simulation and Design for Reliability Enhancement of VLSI Circuits
I. N. Hajj,* F. N. Najm, S. Bobba, J. Kozhaya
Semiconductor Research Corp.
Our goal is to develop computer-aided design techniques for predicting
the reliability of VLSI circuit designs, to detect if and when the
design does not meet reliability specifications, and to recommend
changes in the design to meet these specifications. In our work, we
have derived statistical techniques as well as worst-case estimation
methods that allow design for reliability to be done at a reasonable
cost. The results also give an estimate of the average and maximum
power drawn by different parts of the design. Fast methods for
estimating worst-case voltage drop in the power bus as well as worst-
case current flows in the bus for electromigration estimation are also
being developed.
An Integrated Design Methodology for Low-Power DSP and Communications
Systems
I. N. Hajj,* N. R. Shanbhag,* S. Ramprasad, S. Bobba
National Science Foundation, MIP-9710235
The goal of this project is to develop an integrated computer-aided
design (CAD) approach for the design of low-power hardware for digital
signal processing (DSP) and communications applications. The approach
incorporates high-level (algorithmic) and low-level (circuit)
parameters and includes novel capabilities for design exploration and
low-power circuit synthesis. The design exploration will be done by
developing low-power constrained algorithm design procedures that
employ an analytic relation between word-level and bit-level signal
statistics. The synthesis effort will incorporate signal statistics,
high-level hardware models, and algorithm transformations to generate
low-power dedicated implementation of DSP algorithms.
Architectural Compiler Techniques for Low-Power Microprocessor Design
I. N. Hajj,* C. Polychronopoulos, N. Bellas, R. Whitestone
Intel Corp.
The aim of this project is to develop hardware/software techniques for
low-power microprocessor design. The hardware modification involves
the addition of a special loop cache. The additional hardware is
designed to reduce power, but not to affect the overall performance of
the design. Compiler modifications techniques necessary for the
hardware addition are also being developed. We plan to use profile-
based techniques to detect the most frequently used basic blocks of
the benchmark programs and cache them in the special loop cache.
Computer-aided Design of Optoelectronic Integrated Circuits and
Optical Interconnects
S. M. Kang,* P. Mena, A. Xiang, J. Yang
NSF Center for Compound Semiconductor Microelectronics; DARPA Center
for Optoelectronics Science and Technology
The aim of this project is to develop accurate component models and
simulation programs that are essential for the analysis and
development of optoelectronic integrated circuits, optical
interconnects, and buses. Circuit models for optoelectronic devices,
such as MSM photodetectors, both edge- and surface-emitting multiple
quantum-well laser diodes, and waveguides, have been developed and
implemented into a simulation circuit-level program, v SPICE.
Also, optical link simulator iFROST has been developed for systems-
level analysis of parallel optical buses in high-performance computing
and communcation systems. Potential applications of these CAD tools
for optical network reliability are being investigated.
iPOINT Testbed for Optical Interconnects
S. M. Kang,* S. G. Bishop,* R. Campbell,* G. Papen,*
NSF Center for Compound Semiconductor Microelectronics; DARPA Center
for Optoelectronics Science and Technology
A fully functional systems testbed is used to develop optoelectronic
subsystems such as optoelectronic transmitter arrays, photoreceiver
arrays, and switching subsystems. Operating systems and softwares are
also being developed for multimedia, video/audio teleconferencing over
optically linked workstations in the Beckman Institute and the Digital
Computer Laboratory. Recently 1 Gbps trunk port has been implemented
using UIUC optoelectronic devices, along with an intelligent queue to
support QoS.
Modeling and Simulation of VLSI Reliability
S. M. Kang,* E. Rosenbaum,* C. C. Teng, L. P. Yuan,
Semiconductor Research Corp.; Texas Instruments, Inc.
Designing reliability into VLSI to obtain first-pass reliable VLSI
devices has become increasingly important in recent years. Both long-
term and catastrophic early life failures will be modeled and
simulated to study VLSI reliability. For the simulation of circuit
performance degradation, new MOS transistor models that include hot
carrier-induced device degradation effects and electrical overstress
have been developed. Both experimental and theoretical investigations
are pursued for development of new models and simulators. Automatic
extraction of parasitic devices in I/O circuits is being developed for
reliability-driven I/O synthesis.
Scalable Optoelectronic ATM Networks
S. M. Kang,* J. Lockwood,* H. Duan, A. Hossain, A. Xiang
AT&T Foundation; National Science Foundation; Defense Advanced
Research Projects Agency
Asynchronous transfer mode (ATM) networks are used to provide high
bandwidth for future information infrastructure. The scalability of
ATM switches and queueing modules is being investigated to maximize
the utility of photonic, electronic, and optoelectronic devices. New
algorithms for switch control, input queueing, and priority control
are being developed and tested on an iPOINT testbed using multimedia
traffic and its model. Hardware modules have been developed and
inserted to enhance the scalability of ATM communications.
Low-Power Digital CMOS Circuits
S. M. Kang,* S. M. Yoo, C. W. Kim
University of Illinois
State-of-the-art VLSI chips are being used in portable systems that
require compactness, high speed, and long battery life. New innovative
circuit design techniques are required for high speed with low power
consumption. Power-minimum high-speed circuit design methods are being
developed to drastically reduce the power consumption of state-of-the-
art CMOS circuits. Several benchmark circuits such as multipliers are
used to demonstrate significant power savings without resorting to
power supply scaling, substrate biasing, or threshold voltage tuning.
Simulation of High-Speed Interconnects
S. M. Kang,* C. Gokner, H. Kutuk
University of Illinois
The interconnects for high-speed circuits and systems need to be
modeled accurately in order to examine the signal integrity and signal
propagation delay times. In this project, we are developing new
modeling and simulation techniques for time-efficient and accurate
simulation of interconnect lines in conjunction with fast MOS timing
simulator ILLIADS. In particular, the interface issues between Ricatti
solver and the method of moment for transmission line analysis are
being investigated for time-efficient and accurate timing simulation
of very high-speed VLSI circiuts wherein inductance effects become
important.
Electrothermal Stress-tolerant Deep Submicron Low-Power Circuits
I. N. Hajj,* S. M. Kang,* E. Rosenbaum,* E. Li, T. Li
Joint Services Electronics Program, N00014-96-1-0129
We plan to develop the scientific and engineering expertise needed to
produce reliable deep submicron, low-power integrated circuits and to
develop I/O protection circuits with electrical overstress (EOS) and
electrostatic discharge (ESD) resilience. We are also exploring the
physics of device operation under short duration, high current stress,
and at high temperature. We are developing models and guidelines for
reliable I/O protection circuits for both bulk and silicon-on-
insulator (SOI) CMOS technologies. We will also develop design methods
to ensure that on-chip interconnects have electromigration resilience
while consuming a minimum of chip area. To evaluate the current stress
levels in large-scale metallic interconnects, we are developing
efficient statistical techniques.
Thermal Limitations of Interconnect Design Rules
S. M. Kang,* E. Rosenbaum,* Y. K. Cheng, E. Li, C. H. Tsai
Texas Instruments, Inc.
Electromigration and the interconnect parasitic resistance increase
are thermally activated; therefore, interconnect temperature must be
correctly modeled in order to predict (simulate) electromigration
reliability and electrical performance. Circuit design with the aid of
accurate reliability simulation tools is far preferable to blind
application of overly conservative reliability design rules, which
generally result in significant area and performance penalties. We are
developing accurate temperature models for interconnects, which
account for joule heating, heat flow from the substrate, and heat flow
from neighboring interconnects. A three-dimensional, geometry
conserving layout extractor has been developed. Temperature models
have been implemented in temperature-dependent timing simulator
ILLIADS-T.
Power Estimation in VLSI Circuits
F. N. Najm,* J. Kozhaya
Semiconductor Research Corp.
Excessive power dissipation in ICs discourages their use in portable
equipment and causes overheating, which can lead to soft errors or
permanent damage. The main conceptual difficulty in power estimation
is that the power depends on the input signals driving the circuit, a
more active circuit will consume more power. To account for this, most
recently proposed power estimation methods are based on a
probabilistic approach, but are limited to combinational circuits. The
aim of this project is to handle large VLSI circuits, allowing for
sequential and other circuit architectures. We handle sequential
behavior by using statistical estimation techniques to measure the
latch output statistics. From the results, it is possible to compute
the total power.
High-Level Power Estimation in VLSI Circuits
F. N. Najm,* M. Nemani
Intel Corp.; National Science Foundation, MIP 96-23237, MIP 97-10235;
Semiconductor Research Corp.; Rockwell International
The high density of modern integrated circuits has led to unacceptably
high levels of chip power consumption. Because of limited battery
life, this presents a severe limitation in the design of portable or
mobile electronics. Even in line-powered equipment, high-power chips
require expensive packages and heat-sinks. We are developing power
estimation techniques that work at high levels of abstraction, so that
the power can be estimated even before the gate-level design
description is available.
Power Macromodeling for High-Level Power Estimation
F. N. Najm,* S. Gupta
Intel Corp.; National Science Foundation, MIP 96-23237, MIP 97-
10235; Semiconductor Research Corp.; Rockwell International
Power estimation from a high level of abstraction is important in
order to provide early warning of major power problems. If part of the
chip is reused from a previous design, then the internal details of
that part are known. It would be very efficient to have a "high-
level" model of the power dissipation for this part, a
"macromodeling for power" technique. At the lowest level of
abstraction, this is a problem of "library characterization"
for power, where one is trying to model with as much detail as
possible the power dissipation of a transistor-level cell
representation by a gate-level power model. At the next level, we want
to extend this macromodeling technique to larger cells or, in general,
any combinational or sequential block specified at the gate or lower
level.
Reliability Engineering for Integrated Circuits
F. N. Najm,* G. Yoh
National Science Foundation, MIP 96-23237
We are developing a methodology for designing reliable ICs which would
allow designers to do reliability prediction and reliability
budgeting. Under reliability prediction, the system will accept a
description of the design at either a gate or higher level and will
provide an estimate of the chip reliability. Under reliability
budgeting, a specified failure rate or MTF for the whole chip will be
partitioned among the different chip components to provide reliability
targets for smaller pieces of the design. This allows designers to use
less conservative design styles, thus requiring less silicon area and
improving chip density and performance without sacrificing overall
chip reliability.
Worst-Case Activity Prediction
F. N. Najm,* J. Kozhaya
National Science Foundation, MIP 96-23237
The reliability of semiconductor integrated circuits depends both on
the manufacturing process and on the circuit design. On the design
side, high levels of switching activity inside a CMOS chip are a root
cause of many reliability problems, such as electromigration and hot-
carrier degradation. In this work, we aim to provide efficient and
accurate prediction of the worst-case (highest) realistic levels of
switching activity inside a logic circuit. By realistic, we mean that
the sought activity levels should correspond to real circuit operation
under realistic input vectors and not to fictitious and arbitrary
inputs.
Reliability-driven CAD System for Deep-Submicron VLSI Circuits
S. M. Kang,* E. Rosenbaum,* C. H. Tsai, E. Li, T. Li,
U.S. Air Force Rome Laboratory
The goal of this project is to develop a hierarchical reliability-
driven CAD system for concurrent checking of performance and
reliability during the design of deep-submicron VLSI/VLSI circuits. At
the top of the hierarchy lies reliability design rule checking. We are
developing design verification capabilities against hot-carrier-
induced degradation, time-dependent dielectric breakdown,
electromigration, and electrostatic discharge/electrical overstress.
Below rule checking in the design hierarchy are timing and circuit
simulation. The timing and circuit simulator ILLIADS-R and iETSIM are
enhanced to simulate circuit reliability in addition to performance. A
user-friendly interface is being developed for remote uses across the
Internet or in a group environment.
Electrothermal Simulation of Silicon ICs
S. M. Kang,* E. Rosenbaum,* Y. K. Cheng, L. P. Yuan
Intel Corp.
Increased power yields higher operating temperatures. Circuit-level
electrothermal simulation is not a feasible tool for studying VLSI-
size circuits. This project involves adding temperature models to a
timing-level simulator that can handle VLSI circuits. The circuit is
partitioned into blocks. Power consumption for each block is
calculated, and then the chipwide temperature distribution is
constructed. Once the temperature distribution is known, device models
are adjusted to local temperatures, and the timing simulator is used
to study chipwide performance. Also, users can specify average power
consumptions of several hundreds of modules on chip to obtain the on-
chip temperature profile. We are investigating computationally more
efficient methods.
Electrostatic Discharge Protection in SOI-CMOS Circuits
E. Rosenbaum,* P. Raha
National Science Foundation, ECS 96-23424 CAR
Silicon-on-insulator CMOS technology holds great promise as an
improved substrate for low-power, high-speed integrated circuits.
However, SOI-CMOS ICs will not be produced on any large scale if they
are susceptible to electrostatic discharge (ESD) induced failures.
This project will answer the fundamental questions about the ESD
reliability of SOI-CMOS technology. Thermal modeling, design of
protection devices, and experimental testing form the basis of this
investigation. Device models and stress limits developed in this
research project will be implemented in a CAD tool for full-chip ESD
reliability verification.
Characterization and Optimization of Deuterium-annealed Ultrathin
Dielectrics for 100 nm CMOS Applications
E. Rosenbaum,* L. F. Register, E. Li, J. Wu
Semiconductor Research Corp.
Under optimized anneal conditions, deuterium can passivate the Si/SiO2
interface and, under subsequent electron injection, the silicon-
deuterium bonds are much more difficult to dissociate than the Si-H
bonds formed during the conventional forming gas anneal. Detailed
studies are being performed to characterize fully the hot carrier and
oxide reliability of deuterium-annealed MOS transistors, to determine
whether there are any interactions between the deuterium and other
chemical species (such as boron) introduced during device processing,
and to ascertain the role of hydrogen in gate oxide degradation. It is
anticipated that deuterium annealing will allow the use of
performance-driven drain engineering and perhaps of new gate
dielectric materials.
Background Calibration Techniques for High-Resolution ADCs
B. S. Song,* C. W. Park
National Science Foundation, MIP 97-11010
High-resolution ADCs, when limited by component mismatch or circuit
nonidealities, have relied on corrective measures such as trimming or
electronic calibration. Two key concepts explored are dithering and
nonlinear interpolation, which are to corrupt the signal with a known
dither and to subtract the dither digitally later. Since the
calibration dither voltage injected into a specific stage experiences
a path gain set by a capacitor ratio, the capacitor ratio error of the
path can be measured indirectly by measuring its dither gain. The
ultimate goal of this project is to maintain high-frequency
performance by adding real-time trimming circuits operating in
background and leaving fast original architectures intact.
Low-Jitter Frequency Synthesizers with an Integrated VCO
B. S. Song,* W. G. Rhee
Rockwell International
Frequency synthesizers for communication receivers demand a very low-
jitter performance of a high-Q VCO because the reference frequency of
the PLL is usually the channel spacing. Because of the phase detection
at this low freqiency, the PLL loop doesn't effectively suppress the
phase jitter of the VCO. This research is to explore the feasibility
of using an integrated ring-oscillator VCO for frequency synthesizer
applications. The high level of the VCO phase jitter will be
suppressed by the PLL loop gain by using a phase detector operating at
much higher frequencies than the channel spacing. The jitter generated
by the fractional-N divider will be whitened, either using a sigma-
delta or a randomizing technique.
Low-Voltage NTSC Decoder for Portable Applications
B. S. Song,* M. J. Choe
Samsung, Inc.
New digital video applications have created a need for low-
voltage/power NTSC decoder with digital outputs for portable
applications. NTSC decoders are being implemented digitally with
front-end ADCs. Although the current approach is sound and flexible
due to its digital-domain implementation, it suffers from the large
chip area and power consumption. We propose to determine the
feasibility of implementing the same function with less chip area and
power with lower supply voltage. For this, we will investigate the
feasibility of partitioning the NTSC decoder system for a mixed
analog/digital implementation with more analog functions incorporated.
For TV audio, a completely digital FM demodulator is being developed.
Micropower Low-Voltage Video ADCs
B. S. Song,* H. S. Chen
Harris Semiconductor Corp.
A demand for digital signal processing has grown rapidly in the high-
quality video reproduction areas such as multimedia and high-defintion
television. Existing monolithic flash-type ADCs for video purposes,
although very fast, have been limited to typical 8-bit applications,
and require excessive area and power. The proposed research will be
focused on the application of scaled CMOS technologies to low-voltage
10-bit video-rate data conversions. The goal of the research is to
develop and prototype a 10-bit CMOS video ADC using a single 3-V
supply and 25 mW. A substantial power savings is obtained not by
efficient de-signs but by efficient architectures, such as recycling
ofamps, capacitive reference dividers, and purely dynamiccomparators.
A Digital FM Demodulator for FM, TV, and Wireless
B. S. Song,* M. J. Choe
Samsung, Inc.
An FM demodulator is being implemented digitally in software using a
quadricorrelator algorithm to make it compatible with future digital
wireless and FM receiver systems. The proposed digital FM demodulator
uses a sinc-cube decimation filter with its first zero either on the
alternate or on the adjacent channels for high channel selectivity, a
digital differentiator using a three-point approximation for frequency
discrimination, and a digital division for AM rejection. A bitstream
FM signal from a fourth-order bandpass delta-sigma modulator is FM-
demodulated to exhibit a SNDR of 71 dB, a THD of 0.01%, and an AM
rejection of 77 dB in simulations using a signal band limited to
1/200 of the sampling frequency and amplitude-modulated with a
modulation index of 0.9 (90% AM).
Direct-Conversion Receiver with Path Offset, Gain, and Phase
Correction
B. S. Song,* Y. H. Kim
Motorola, Inc.
Direct conversion to dc can greatly simplify RF receiver architecture,
but it suffers from three major errors: dc offsets, amplitude
imbalance, and phase error. We propose to demonstrate an offset and
image-suppressed direct-conversion system and to reduce cost and power
consumption of analog front end without sacrificing overall BER. The
proposed architecture is generic in most bandpass digital signal
processing applications, and future communication RF techniques will
rely heavily on the availability of such components as we propose to
develop in this work.
Low-Spurious DACs for Wireless Applications
B. S. Song,* A. Bugeja
Motorola, Inc.
We are conducting research into the design of digital-analog
converters for applications where high speed and resolution are
required, such as wide bandwidth communications. Typical
specifications being considered are sampling rates in excess of 50 MHz
and resolution of 14 bits or higher. The aim is to produce integrated
DACs exhibiting true n-bit dynamic linearity, i.e., SFDR of
approximately -90 dB. The current focus of this research is the
feasibility of using special output stages which can couple to the
analog outputs of a high-speed DAC and provide improved SFDR. We plan
to construct chips in which these stages are integrated with the DAC
on the same die, as well as separate modules.
Low-Power VLSI Algorithms and Architectures for DSL
N. R. Shanbhag,* J. Baker, M. Goel, S. Ramprasad
Rockwell International; Samsung, Inc.
This research seeks to develop low-power equalizer architectures for
digital subscriber loop applications, which includes receivers based
upon discrete multitone transmission (DMT) scheme for asymmetric
digital subscriber loops (ADSL), carrierless amplitude and phase (CAP)
modulation for very high-speed digital subscriber loops (VDSL), and
asynchronous transfer mode (ATM) local area networks (LANs). System
partitioning of functionality into programmable and dedicated
processing units is being determined to achieve the lowest power. A
key feature of our approach is the joint organization of algorithmic
performance and power dissipation via the application of algebraic,
Hilbert, and dynamic algorithm transformations.
Design and Prototyping of Broadband Communications Systems
N. R. Shanbhag,* B. Chau
Analog Devices, Inc.
Adaptive equalizers are a major component of receivers in modern day
communications systems. With the drive toward increasingly higher
transmission rates, there is a corresponding increase in the
complexity and therefore power dissipation and area of adaptive
receivers. This research focuses on the development of low-power
adaptive equalizers via the application of algorithm transformation
techniques. Prototyping of communications algorithms incorporating
these equalizers on a programmable DSP/FPGA platform is also being
done.
Adaptive Computing Systems--Performance Limits and Realizations
N. R. Shanbhag,* M. Goel, R. Hegde, S. Ramprasad,
Defense Advanced Research Projects Agency, DABT63-97-C-0025
This project aims to develop a firm theoretical foundation for mixed
hardware-software system design and a practical design methodology for
adaptive computing systems (ACS) for digital signal processing (DSP)
and communications applications. The theoretical foundation is based
on determining the achievable performance (specifically power
dissipation and reliability) bounds for hardware-software based VLSI
computing systems via an information-theoretic approach. The design
methodology for adaptive computing systems is based on a new class of
algorithm transformations referred to as dynamic algorithm
transformations (DAT). These transformations enable the joint
optimization of algorithm and circuit performance by exploiting
nonstationarities in the signal and user environment.
Fundamental Bounds on VLSI Computation
N. R. Shanbhag,* R. Hegde, L. Wang
National Science Foundation, MIP 96-23737
The goal of this research is to develop an information-theoretic basis
for VLSI computation, to determine fundamental achievable bounds on
VLSI performance, and to investigate methods to achieve these bounds.
We have developed a mathematical basis for power reduction in VLSI
systems in which the computation in a DSP algorithm is viewed as a
process of information transfer with an inherent information transfer
rate requirement. Architectures implementing a given algorithm are
equivalent to communication networks each with a certain capacity.
Numerical calculations of lower bounds on power dissipation for simple
static CMOS circuits as well as pipelined and parallel processing
architectures have demonstrated the usefulness of this theory.
Sparse Random Ultrasound Phased Arrays for Focal Surgery
L. A. Frizzell*
National Institutes of Health, CA66462, SBC Labthermics Technologies,
Inc.
The use of ultrasound phased array, high-intensity focusing systems
for ablation of tissue (surgery) allows electronic control of focal
size and shape, as well as position, thus eliminating the necessity of
a cumbersome mechanical scanning apparatus. While phased arrays have
been employed for medical diagnostic and therapeutic applications
(hyperthermia), they often require a prohibitively large number of
elements. This study will determine if sparsely filled arrays, with
the individual elements randomly located on the array surface, will
facilitate the use of larger elements and spacing than used currently,
reducing the number of elements and amplifiers required.
Second-Generation Commercial Ultrasound Therapy Arrays
L. A. Frizzell,* P. K. Mandava
National Institutes of Health, CA65206, SBC Labthermics Technologies,
Inc.
This study involves the continued development of a new generation of
commercial ultrasound applicators and associated hardware/software
capable of improved heating uniformity and depth control within the
body, with specific application to thermal therapy for breast cancer
and chest wall recurrence. Specifically, applicators will be
constructed and tested that will offer (1) higher frequency operation
to limit penetration depth where indicated, (2) simultaneous dual
frequency operation so the frequency can be independently selected for
the different elements in the applicator array, and (3) an improved
means for coupling these new applicators for breast and chest wall
treatments.
Development of a Dermofluorometer to Monitor Skin Fluorescence and
Blood Flow Following Administration of Fluorescein
R. L. Magin,* A. Zhang, D. Oh
UIUC-VA Medical Center, Danville, Ill.
This pilot research study is aimed at the development of a dynamic
dermofluorometer for the rapid and continuous recording of tissue
fluorescence. Such an instrument should increase the diagnostic
information provided by fluorescence tissue measurements when
incorporated into a pharmacokinetic model of dye distribution. Thus,
tissue fluorescence changes in response to exercise, localized
heating, or drug therapy could be used to obtain dynamic information
on the physiological state of tissue.
Enhancement of the Teacher Preparation and General Science Education
at UIUC
R. L. Magin,* B. Bruce
National Science Foundation, DUE 91-55899
The general goal of this project is the development of improved
teaching methods and materials for preparing science and mathematics
teachers. The specific aim is to develop models and examples that
incorporate new science and engineering instructional materials into
teacher preparation courses for elementary and secondary education
teachers. This effort is a collaboration between the College of
Education and the College of Engineering at UIUC. Current advances in
science, engineering, and bioengineering research in the College of
Engineering are being transferred into teacher preparation courses and
internships offered by the College of Education.
Ultrasonic Anistropy of Biological Tissues
W. D. O'Brien, Jr.,* K. A. Topp
National Institutes of Health, National Cancer Institute, CA09067
The object of this project is to evaluate ultrasonic anisotropy of
biological tissues. This work will impact the ability to diagnose
malignant tissue whereas current diagnostic ultrasound capability can
only identify whether the tissue is abnormal and not necessarily
malignant. The quantification of ultrasonic propagation properties is
dependent on tissue anisotropy, and therefore it is necessary to have
the capability to assess tissue anisotropy in order to diagnose tissue
abnormalities such as malignancies. The approach is to measure the
ultrasonic propagation properties which include propagation speed,
attenuation, and backscatter. The approach is also to develop a
theoretical basis for the ultrasonic anisotropic behavior of
propagation speed, attenuation, and backscatter.
Acoustical Characterization of Soil to Evaluate Subsurface Imaging
Requirements
W. D. O'Brien, Jr.,* R. G. Darmody (Agronomy),
U.S. Army Construction Engineering Research Laboratories, DACA88-94-D-
0008
The objective of the research program is to develop the basic acoustic
propagation and backscattering database to evaluate the acoustic
imaging tradeoffs for detecting and characterizing buried artifacts in
ground soil.
Human Ultrasound Dosimetry in Ovarian, Embryonic, and Fetal
Examinations
W. D. O'Brien, Jr.,* D. S. Ellis, E. D. Swiney
National Institutes of Health, HD 21687, SBC University of Cincinnati
Medical Center
The specific research aims are to measure the ultrasonic energy
delivered to the human ovary, early embryo, and mid-trimester fetus
using currently available diagnostic imaging equipment. Specially
designed hydrophones will be placed as close as possible to the
ovaries in normal volunteers. Exposure to the embryo will be
determined by placing the hydrophones as close as possible to the
embryo in utero. Once the dosimetry in these clinical situations has
been established, then meaningful data regarding the effect of
diagnostic ultrasound in human pregnancy can be obtained and
"safe" levels of ultrasonic energy established for patients
of varying size and gestation.
General Solutions for Tissue Temperature Increases
W. D. O'Brien, Jr.,* M. Goveygov
National Institutes of Health, National Cancer Institute, CA09067
The objective of this research is to evaluate theoretical tissue
temperature increases due to focused diagnostic ultrasound fields
under various realistic tissue models. The approach is to apply the
point-source, harmonic, spherical solution of the linear acoustic wave
equation to the appropriate source aperture geometry for the
particular tissue model, from which the general acoustic pressure
field distribution is obtained. The tissue transient and steady-state
temperature increase are then calculated by applying the point-source
solution of the bioheat transfer equation to the calculated field
distribution.
Acoustic Imaging of Defects in Shelf-Stable Food Packages' Microbial
Integrity
W. D. O'Brien, Jr.,* S. A. Morris* (Food Sci.), A. Ozguler (Food
Sci.), P. K. Rooney
University of Illinois Value-added Research Opportunities Program,
Agricultural Experiment Station
The long-term objective is to further the state of the art of
detecting defects that will compromise the integrity of new types of
food packages by using a research team approach (experts in packaging,
acoustic imaging, and challenge testing). The SLAM technology also
operates at much higher frequencies (commercially available up to 500
MHz), thus providing the capability of achieving resolution limits of
4m. The short-term objective of this pilot study is to identify the
fundamental resolution limit by the Bioacoustics Research Laboratory's
SLAM (operates at 100 MHz) of detecting packaging defects in
order to develop a theoretical basis to improved image resolution
capabilities.
Subsurface Acoustic Imaging of Cultural Artifacts
W. D. O'Brien, Jr.,* D. C. Munson, Jr., R. G. Darmody (Agronomy), C.
A. H. Frazier, N. Cadalli, E. D. Swiney
U.S. Army Construction Engineering Research Laboratories, DACA88-96-K-
0002
The objective of the research program is to evaluate the feasibility
for subsurface detection of cultural artifacts. The hypothesis is that
subsurface artifacts can be detected using various acoustic imaging
approaches. The principal unknowns are the axial and lateral spatial
resolutions required as a function of buried artifacts in ground soil
and the contrast resolution at which detection can be achieved for
various soil types and conditions.
Simulation of Ultrasound Phase Aberration in Biological Tissues
W. D. O'Brien, Jr.,* Z. Q. Wang*
National Center for Supercomputing Applications
One-dimensional (linear) array transducers are used with virtually
every diagnostic ultrasound imaging system with major efforts to
develop efficient 2-D array transducers. Array imaging requires a
medium with a homogeneous propagation speed to yield the optimal
resolution. However, phase aberration results from tissue
microstructure inhomogeneities, which seriously degrades the focusing
of the ultrasonic beam and thus limits the resolution of modern
ultrasonic imaging systems. This study aims to solve the 3-D (spatial)
or 4-D (spatial and temporal) acoustic wave equation in a medium of
variable propagation speed and density with the finite-difference time
domain (FDTD) method and to analyze the time delay dependence of
ultrasonic pulses on the tissue properties.
Coupled Rayleigh Wave Propagation in an Elastic Plate
J. G. Harris* (Theoret. & Appl. Mech.),
American Chemical Society, Petroleum Research Fund
The longer service life of structures such as pipelines means that
they must be monitored for damage more thoroughly and over a longer
period of time. Using coupled surface waves may be one way to inspect
the inner (not easily accessible) surface of a pipe from its outer
surface. Moreover, if the damage were a small surface-breaking fatigue
crack, then a surface wave would readily detect the crack because the
surface wave would strike the crack broadside, or if the damage were
corrosion, then a surface wave would be more severely attenuated by
the patch of corrosion at the surface than a bulk wave. The study aims
to evaluate coupled surface waves so that they can be used for such
nondestructive testing.
Real-Time Acoustic Imaging Development for Defects Detection in Shelf-
Stable Food Packages
W. D. O'Brien, Jr.,* S. A. Morris* (Food Sci.), A. Ozguler (Food
Sci.), P. K. Rooney
University of Illinois Value-added Research Opportunities Program,
Agricultural Experiment Station
Typical real-time ultrasonic imaging is performed with phased array
ultrasonic transducers using the ultrasonic backscattered signal.
Previously we demonstrated that ultrasonic backscattered signal
evaluation can detect packaging defects better than the system's
resolution limit. This was accomplished with the development of a new
pulse-echo image processing strategy called BII (backscattered
integrated imaging)-mode imaging. These images were constructed under
laboratory (static) conditions with off-line computer processing
(nonreal-time processing). The research aim is to evaluate the extent
to which the BII-mode pulse-echo technique can detect and classify
packaging defects under real-time, production-line speed conditions.
Fabrication of Microminiature Devices and Microelectrical-Mechanical
Systems
I. Adesida, T. A. DeTemple, K-C. Hsieh, B. C. Wheeler,
University of Illinois, Critical Research Initiative Program
Applications for microelectrical-mechanical systems (MEMS) which are
being developed include low-cost microoptical mechanical switches for
telecommunications, mechanical devices for microsurgery, and masks for
biological molecule deposition. This project is aimed at high-force
and displacement devices, as well as using dissimilar materials and
creating 3-D utility from planar elements. One approach is to combine
wafer-scale and laser-material processing to join elements which
cannot be fabricated in the same process as silicon. Research in
silicon and laser-material processing is currently being developed to
solve the fundamental issues of MEMS.
A Database System for Neuronal Pattern Analysis
B. C. Wheeler, B. Mihalas; M. Gabriel,* W. T. Greenough, J. Malpeli
(Psychology); M. Nelson, A. Feng, R. Gillette (Physiology &
Biophys.)
National Science Foundation, BIR-95-04842
Neuronal pattern analysis documents the dynamic brain processes of
sensation, perception, learning, and cognition by recording the
electrical activity of brain neurons. Recent advances in multiarray
recording have greatly expanded the rate at which these data can be
obtained, making possible the study of dynamic intercorrelations in
neuronal networks. Computational modeling has fostered major
increments in data-processing requirements, which call for parallel
development of adequate database systems for organization, rapid
access, and sharing of these data. This work establishes a database
system for time series neurophysiological data recorded by the
Neuronal Pattern Analysis Group at the Beckman Institute, carried out
with collaboration from the National Center for Supercomputing
Applications.
Optimizing Data-processing Systems for Grain Evaluation
B. C. Wheeler*
U.S. Department of Agriculture, Northern Regional Research Center
Neural net and other pattern recognition techniques are to be used to
analyze Fourier transform infrared photoacoustic spectroscopic (FTIR-
PAS) data from samples of corn in order to automate the detection of
contaminated corn.
Physical Exercise, Mental Activity, and Brain Plasticity
B. C. Wheeler,* W. T. Greenough* (Psychology)
National Institutes of Health, PHS 2R01 AG10154-07
We propose to use morphological and morphometric,
electrophysiological, immunocytochemical, and behavioral methods in
mature adult and aging cerebellar cortex to determine which synapse
and neuron types in cerebellar cortex exhibit plasticity in response
to learning and to physical exercise; which nonneuronal elements
exhibit plasticity; the molecular mechanisms underlying this
plasticity; and functional correlates.
Precise Control of Neuronal Growth--An Enabling Technology for Neural
Prosthetics
B. C. Wheeler*
University of Illinois; Mary Jane Neer Research Fund
The goal of the proposed work is to create the knowledge needed to
design neurotrophic surfaces for application to neural prostheses. We
have developed a technology which permits "microstamping" of
any protein onto a glassy substrate in patterns with resolution of few
micrometers. The specific aims of the proposal are to optimize this
technology and to extend it to multiple proteins on the same
substrate, to separately control not only neuronal attachment, but
also axonal vs. dendritic growth, and to begin to control attachment
and growth of glia in culture.
Second-Generation IMPACT Predication Technology
W.-M. Hwu,* D. August, D. Connors, J. Braun
Intel Corp.
The first-generation IMPACT predication technology has made a strong
contribution in the area of branch handling and predication-based code
scheduling. The second-generation IMPACT predication technology is
designed to allow much more aggressive exploitation of instruction-
level parallelism within the predicated compilation framework. The
compiler techniques being developed in this project include accurate
global flow analysis of predicated code, partial reverse if-
conversion, advanced predication-based code optimizations, fully
resolved predicates, and advanced predication-based dependence height
reduction. The architecture techniques being developed include
predication-based branch prediction and new predication manipulation
instructions.
Speculative and Predicated Execution Support for Instruction-Level
Parallel Processing
W.-M. Hwu,* D. August, R. Hank, J. Gyllenhaal
National Science Foundation, MIP-9308013
The objective is to provide architecture expertise and compiler
prototypes required for the microprocessor industry to understand the
cost and effectiveness of each level of hardware support. First, the
design complexity of architecture support, including silent
instructions, sentinel hardware, conditional move instructions,
conditional store instructions, and conditional execution of all
instructions, is studied. Second, compiler software is developed: if-
conversion, reverse if-conversion, optimizers, and schedulers that
become increasingly aggressive as the level of architecture support
increases. Third, an integrated approach is defined to coordinate
speculative execution and predicated execution to best improve program
execution performance.
Stability of Profile-based Optimizations for ILP Processors
W.-M. Hwu,* B. Deitrich, D. August, B.-C. Cheng
Intel Corp.
Compilers for instruction-level parallel (ILP) processors often use
profile information to make critical optimization decisions. As new
techniques to support fast profiling continue to emerge, profile-based
optimizations will soon become commercially feasible. However, open
questions remain regarding the stability of profile-based
optimizations in the presence of conflicting execution profile due to
different input sets. This project deals with static program analysis
and code transformation techniques re-quired to minimize the potential
performance variation when using profile information in advanced
compiler transformations.
Intelligent Run-Time Cache Hierarchy Management
W.-M. Hwu,* T. Johnson
Hewlett-Packard Co.
Improvements in memory speeds have not kept pace with increasing
processor clock frequency and improved exploitation of instruction-
level parallelism. Consequently, the gap between processor and memory
speeds is expected to grow, increasing the number of execution cycles
spent waiting for memory accesses to complete. One solution to this
growing problem is to reduce the number of cache misses by increasing
the effectiveness of the cache hierarchy. The objective of this
project is to develop techniques for dynamic analysis of program data
access behavior, which is then used to guide proactively the placement
of data within the cache hierarchy in a location-sensitive manner.
The IMPACT/X86 Compilation Technology
W.-M. Hwu,* D. Gallagher, D. Lavery, M. Merten,
Advanced Micro Devices
The objective of this project is to develop advanced code
parallelization and optimization techniques to take advantage of the
wide issue capabilities of the coming generations of X86 processors.
Techniques investigated include profile-driven optimizations, height
reduction, region compilation, code scheduling for reduction in
register pressure, and register allocation. The project deals with
real system performance and industry standard benchmark programs such
as SPEC. Techniques must deal with real-world constraints imposed by
the X86 architecture.
Illinois Computing Laboratory for Aerospace Systems and Software
(ICLASS)
R. K. Iyer,* J. W. S. Liu,* R. H. Campbell, A. A. Chien,
National Aeronautics and Space Administration, NAG 1-613
The Illinois Computing Laboratory for Aerospace Systems and Software
(ICLASS) is a NASA center for excellence in aerospace computing. Its
research focus is in the areas of parallel architectures and
algorithms, reliable and fault-tolerant computing, real-time and
secure systems, and information systems technology. Problems being
addressed include system-level functional test generation, design of
heuristics for nonlinear global optimization, advanced compilation
technology for high-performance, reliable streams in ad hoc networks,
design and validation of dependable systems, very low-cost fault
tolerance for heterogeneous networked computing, analysis of
distributed discrete-event simulation algorithms, open and composable
real-time systems, an agent-based architecture for supporting
application aware security, system service platform for distributed
multimedia applications, multimedia analysis and retrieval system,
three-dimensional vision, predictable communication, and performance
analysis and parallel I/O.
Networks and Validation
R. K. Iyer,* L. Chen, Z. Kalbarczyk, D. Stott
Tandem Computers, Inc.
This project focuses on the design and validation of reliable cluster
computing systems. The issues addressed include the reliability of
switching technologies, the design and implementation of MPI-based
protocols to provide adaptive levels of fault tolerance, the extension
of MPI to include fault tolerance, and the validation of cluster
computing systems. The design topics will address methods for ensuring
predictable dependability and responsiveness in network environments.
A primary focus will be to develop efficient techniques for providing
early error detection and rapid recovery. Validation topics include
validation of complex, high-performance, networked configurations.
Validation will be from fault tolerance, robustness, and performance
perspectives.
A Design Framework for Dependable, High-Performance Computing Systems
R. K. Iyer,* M.-C. Hsuen, Y.-M. Chang, Y. Huang,
Defense Advanced Research Projects Agency, DABT63-94-C-0045
There is a need for a high level of dependability in computer systems
such as aircraft and aerospace systems, medical and automotive
equipment, and high-speed network switching devices. This research
will develop an integrated design framework in which developers of
these systems can eliminate dependability risks early in the design
process. Using relatively simple descriptions of the system's
behavior, designers can test for dependability in a hierarchical
manner, from the chip level to the system level, long before the
system is built. This approach helps ensure the dependability of
critical systems while reducing the time, effort, and cost of
developing them. This is a joint project with Stanford University.
Research Equipment for High-Speed Computing and Network Initiative
R. K. Iyer,* B. Hajek,* W. K. Jenkins,* F. N. Najm,*
National Science Foundation/Academic Research Infrastructure Program
This project is to develop a reliable, high-performance computing and
network infrastructure that will allow researchers at the Coordinated
Science Laboratory to explore next-generation, ultrahigh-bandwidth
networks (wireless and cabled, including the NSF vBNS National
Backbone) with respect to speed in excess of 1.3 Gbps, configuration
topologies, and scalability; to explore reliable network computing
design alternatives; and to develop electronic design algorithms and
methodologies heretofore not possible or practical with lower
bandwidth and slower computing systems.
Design of Reliable VLSI Architectures
J. H. Patel,* L. Rudnick, S. Venkataraman, J. Chandy,
Semiconductor Research Corp.
The objective of this research is to develop tools and methodologies
for design of VLSI systems for testability, reliability, and
manufacturability. The complexity of VLSI systems has increased the
need for the development of chip design methodologies that emphasize
easily provable and manufacturable functionality, performance, and
reliability. This program addresses a wide range of design issues,
each dealing with various aspects of reliable VLSI design, including
research in fault simulation, test generation, design and synthesis
for testability, and fault diagnosis.
Illinois Genetic Framework for Testing and Diagnosis
J. H. Patel,* L. Rudnick, G. Saund, J. Newquist, J.-K. Zhao, P. Bolte
Defense Advanced Research Projects Agency, DABT63-95-C-0069
The objective of this work is to develop an automatic test generation
and diagnosis system for the large chips envisioned by the high-
performance computing (HPC) and communications industry. Testing is a
major roadblock in the design and manufacture of large complex chips,
and the problem of testing is getting more difficult with the
increasing size and complexity of chips. Genetic algorithms (GAs) have
been demonstrated to provide an effective framework for test
generation. Our goal is to extend this GA framework to allow for the
complex circuitry envisioned in the next generation of HPC systems.
Algorithm Development in Support of Computer-based
Performance/Dependability Evaluation
W. H. Sanders,* D. Deavours, D. Obal
Motorola Satellite Communications
The objective of this work is to extend existing and develop new
performance and dependability evaluation algorithms, including new
methods to speed up simulation, reduce the rate of state-space growth
in analytical state-based methods, and extend the domain of models for
which analytical methods may be applied. Existing methods are unable
to solve for combined performance/dependability (performability)
measures, needed in complex, degradable, satellite networks. The
impact of this work will be shown through prototype implementations in
UltraSAN, a stochastic activity network-based software package for
performance/dependability evaluation.
QBRC--Quality-based Reliable Computing
W. H. Sanders,* D. Deavours, J. M. Doyle, G. P. Kavanaugh, D. Obal, J.
Sowder, A. Stillman, A. Williamson
Defense Advanced Research Projects Agency, DABT63-96-C-0069
The goal of this work, conducted jointly with Purdue University and
the U.S. Navy, is to develop new approaches to dependability design
and analysis that are failure-, application-, and system-
comprehensive. The work at the University of Illinois will focus on
assessment techniques, developing an application-independent model
specification language and techniques to solve the specified models.
Together with the work at Purdue and the navy, this work will provide
tools for analysis that guarantee rapid real-time recovery, consider
the highly networked nature of current military C2 computing
environments, and provide for the impact of degraded services on
command decisions.
Improved Techniques for Parallel Discrete Event Simulation
W. H. Sanders,* D. Deavours
National Aeronautics and Space Administration ICLASS
The goal of this research is to address important problems in computer
system modeling with the purpose of providing practical algorithms for
the analytical/numerical solution of systems represented in high-level
formations, such as stochastic activity networks. In particular, we
are investigating methods to reduce the memory necessary to solve
numerically systems represented in high-level formalisms while still
obtaining solutions in a reasonable amount of time. Solutions to these
problems are necessary to make practical the evaluation of complex
space and aerospace systems.
A Quality-of-Service Approach to Survivability
W. H. Sanders,* M. Cukier, D. Deavours, H. Duggal, D. Henke, A.
Ibrahim, J. Pistole
Defense Advanced Research Projects Agency, Subcontracted from GTE
Internetworking
Current large distributed applications cannot specify the
dependability they require from remote objects and subsystems and
cannot adapt to changes in resource availability. The objective of
this project is to make dramatic improvements in the specification of
dependability requirements in the prediction of dependability under
varying conditions, and in the adaptability of the applications and
resource management strategies by providing infrastructure mechanisms
to support dynamic behavior. The goal is to specify an application's
availability requirements through defining a set of acceptable
operating regions and adapting when we predict that various thresholds
of predicted dependability will not be met.
Survivability of Large-Scale Information Systems
W. H. Sanders,* M. Cukier, J. Ren, C. Sabnis
Defense Advanced Research Projects Agency, subcontracted from GTE
Internetworking
This work provides a methodology for specifying the survivability that
an application desires, in terms of the quality of service delivered
to it, and mechanisms and policies that can be used to achieve the
desired survivability, in terms of the specified measures. Choices of
policies and mechanisms are not easy, and it is not usually obvious
how a change in resources will translate to a change in survivability.
We provide a method to specify the desired survivability and a
specification of what information must be collected to make adaptation
decisions and implement several mechanisms that can aid in building a
survivable system.
Adaptive Resource Management in Mobile Computing Environments
B. Vaduvur,* S. Ha, K. Lee, S. Lu, J. Mysore
Defense Advanced Research Projects Agency, F30602-96-1-0319
The objective of this research is to develop an integrated services
network architecture across hybrid ad hoc packet cellular and wireline
networks. We propose a new type of quality of service called adaptive
service, which addresses the unique requirements of a mobile computing
environment, while also being compatible with traditional integrated
services in wireline networks. This research develops the network
architecture and resource management algorithms required for providing
adaptive service in hybrid mobile computing environments.
PRAYER -- A Platform for Adaptive Computing and Seamless Mobility over
Heterogeneous Wireless Networks
B. Vaduvur,* D. Dwyer, V. Gupta
Texas Instruments, Inc.; Equinox Solutions; University of Illinois
The objective of this research is to develop a distributed computing
platform across hybrid wireline/wireless networks to support seamless
user mobility across different networks. As a result of mobility
between different networks with vastly different resources, the
applications need to adapt gracefully to dynamic changes in perceived
network quality of service. We are building the PRAYER distributed
system, which features systems support for both seamless mobility and
adaptive computing.
Design of a Supervector Coprocessor for Large-Scale Digital Signal
Processing
B. W. Wah,* C. W. Li, P. H. Chang
Rockwell International
We utilize emerging VLSI technologies that allow tens to hundreds of
vector pipelines to be implemented in one chip. Instead of competing
for precious area in the same chip as regular instruction-set
architectures, we design and evaluate a supervector processor in a
separate chip. This is feasible as vector instructions, once
initiated, can continue to execute until completion without close
supervision by the instruction-set architecture. This architecture is
particularly suitable for computation-intensive loop-based
applications in digital signal processing. We are studying three
interrelated issues: (1) architecture of coprocessor,
(2) software for exploiting parallelism, and (3) system
simulation and implementation. Our design will allow computation-
intensive loops to be executed at a rate far exceeding that provided
by current coprocessors.
Nonlinear Global Optimization
B. W. Wah,* Y. Shang, T. Wang, Z. Wu, W. L. Qian
National Science Foundation, MIP 96-32316
In this project, we develop a method called NOVEL (Nonlinear
Optimization Via External Lead) for solving continuous and discrete
global optimization problems. These problems are characterized by a
nonlinear objective function, with or without a collection of
nonlinear constraints. Such problems exist in many engineering
applications that include operations research, signal processing, and
function optimization. NOVEL addresses the balance between global
search and local search, using a trace to aid in identifying promising
regions before committing to local searches. We are applying NOVEL to
find significantly better solutions than existing ones in filter-bank
design, neural network learning, and constraint-satisfaction problems
in operations research and combinatorial optimization.
Resource Scheduling and Digital Signal Processing in Local Area and
Mobile Networks
B. W. Wah,* J. Monks, X. Su
National Science Foundation, MIP-96-32316
In this project, we study issues related to the efficient operation
and resource scheduling of local area and mobile networks. We study
four related issues in resource scheduling: (1) efficient contention
of shared network channels using a window-based multiaccess protocol,
(2) intelligent filtering of statistical status information to
aid in resource scheduling and network monitoring, (3) efficient
placement and migration of data and information to reduce network
traffic, and (4) design of filter banks and digital signal processors
for computer network-based real-time multimedia applications. We are
developing a prototype system to integrate solutions developed for
each of these issues.
Basic Evaluation and Design Techniques for High-Speed Communication
Networks
B. Hajek,* M. Alanyali, J. Giles, L. He, K. Mitzel,
National Science Foundation, NCR 93-14253
Performance evaluation and design for communication networks of the
future is conducted. Emphasis is placed on large, high-speed networks.
Both optical and electronic networks are considered. Topics include
(1) spectral response of queues and diffusion approximation, (2)
continuous traffic in packet switches, (3) multirate circuit switches,
(4) optical interconnection, and (5) dynamic load balancing. Analysis
consists of a mixture of exact probabilistic and combinatorial methods
and simulation. Design is motivated by modeling and analysis and aided
by optimization tools of both combinatorial and nonlinear iterative
types.
Wireless Distributed Multimedia Communication Networks
B. Hajek,* U. Madhow,* D. V. Sarwate,* H. Chaskar,
U.S. Army Research Office, DAAH04-95-1-0246
The goal of this research is to investigate basic issues involved in
providing multimedia communications over a heterogeneous network of
both wireless and wireline links. Topics under investigation include
wireless multimedia networks, routing and congestion control, adaptive
coded modulation for spread-spectrum communication systems, and the
interface of wireless networks to high-speed wide-area wireline
networks.
Acquisition and Demodulation for Wireless Communications
D. L. Jones,* U. Madhow,* D. V. Sarwate,* B. Nollett,
Joint Services Electronics Program, N00014-96-1-0129
This research project seeks to develop robust but near-optimal methods
for timing acquisition and demodulation for wireless environments.
Multiuser and single-user settings and narrowband and wideband
interference are considered in the design and performance evaluation
of different receiver structures.
Key Problems in Wireless Communications
U. Madhow,* D. Warrier
National Science Foundation CAREER Award, NCR 96-24008
This project is an exploration of fundamental problems arising from
wireless applications, including topics ranging from transceiver
design for multiuser communications to design principles for
heterogeneous networks with both wireless and wireline links.
Adaptive Interference Suppression for the Demodulation of Direct-
Sequence CDMA Signals
U. Madhow,* L. Galup, L. J. Zhu
U.S. Office of Naval Research, N00014-95-1-0647
Adaptive interference suppression methods for the demodulation of
direct-sequence CDMA signals will be investigated with a view to
determining their practical significance for future system designs.
Low-complexity methods of exploiting spatial diversity in addition to
the inherent time-diversity of direct-sequence CDMA signals will be
developed. The complexity-performance tradeoffs for adaptive receivers
will be investigated. Analysis and simulations for a typical wireless
environment with fading, multipath, and shadowing will be used to
decide whether the potential gains in capacity and performance
promised by adaptive methods can be truly realized in practice.
Interference Suppression for CDMA Systems
U. Madhow,* E. Visotsky
Motorola University Partnerships in Research Program
This project is an invention and performance evaluation of
interference suppression algorithms for enhancing the performance of
CDMA systems conforming to the basic IS-95 format, as well as
obtaining low-complexity adaptive interference suppression schemes
that form the basis for the design of future CDMA systems with higher
capacity.
Channel Codes for Digital Communications and Storage Systems
A. Vardy,* D. Agrawal, A. Trachtenberg, R. Kötter
National Science Foundation, NCR 94-09688
Our objective is to investigate block and lattice charged codes with a
new approach and to exploit the advantages of this approach to provide
bounds on decoding complexity and to develop efficient maximum-
likelihood decoders. The precise trade-off between complexity and
performance is studied. We also investigate modulation codes for
input-constrained channels. Viewing block codes as dynamical systems
makes it natural to consider applying results from algebraic coding
theory for the design of modulation encoders. Ways of integrating a
prescribed error-correction capability within such encoders are also
studied.
Data Transmission Techniques -- Trellis-Decoding and Beyond
A. Vardy,* D. Agrawal, A. Trachtenberg
We will investigate creative new techniques for reliable transmission
of digital information. The main objectives are to achieve a deep
theoretical understanding of the underlying problems and to develop
practical coding schemes that can be implemented in real applications.
Intersymbol interference channels are emphasized, as are the digital
speech and image transmission channels characterized by unequal input
probabilities and subjective distortion criteria. Our research
comprises two major activities: to extend prior work in trellis
structure and trellis decoding of block and lattice error-correcting
codes and to develop novel data transmission techniques particularly
suited to specific channels of practical importance and extending
beyond the classical error-control approach.
Channel Coding Techniques for Low-Complexity Source Coding
Applications
A. Vardy,* D. Agrawal, A. Trachtenberg
National Science Foundation, NCR 94-15860
This project investigates channel coding techniques for source coding
applications with an emphasis on image, video, and speech coding
applications. The main objectives are a theoretical understanding of
combined source-channel codes and development of practical algorithms
for such applications as low-bandwidth video compression and low-delay
speech coding. Specifically, very narrow bandwidth transmission
channels require efficient coding schemes to protect the transmitted
source information from channel error corruption. The project also
explores low-complexity techniques needed for low-delay real-time
implementations.
Construction and Decoding of Euclidean-Space Codes
A. Vardy,* D. Agrawal, A. Trachtenberg, R. Kötter
David and Lucile Packard Foundation
Long codes and high-dimensional constellations are necessary to
achieve high coding gains over the uncoded quadrature amplitude
modulation signaling. Currently, the complexity of decoding high-
dimensional constellations is well beyond the reach of today's
technology. In this research, we are developing new techniques for
efficient bounded-distance decoding of high-dimensional signal
constellations. We anticipate that these techniques will make coding
with such constellations not only feasible in principle but
practically implementable with high-speed, low-power hardware, which
in turn will make it possible to achieve very high effective coding
gains on band-limited Gaussian channels, at an affordable complexity.
Transmission, Networks, and Storage Matched to the Physical Layer
R. Blahut,* A. Vardy*
Joint Services Electronics Program, N00014-96-I-0129
This research addresses the development of single-user and multiuser
communication techniques that lie at the intersection of communication
theory, information theory, and error control codes and studies the
effects of amplitude constraints on the capacity of and signaling for
practical channels. The second activity investigates the practical use
of error-control encoding/decoding schemes matched to certain
transmission and storage channels. The third area investigates source
coding for packet networks and narrowband channels. We examine the
effects of channel errors from theoretical and algorithmic
perspectives in order to develop effective data compression and coding
techniques for such applications as speech and video in power-
constrained environments.
Synthesis of Practically Implementable Robust Controllers
B. Bamieh,* B. Shu
National Science Foundation, ECS 93-09123
This project is centered around the idea of incorporating general
implementation constraints and requirements in the theory of robust
controller design. One aspect is the design of sampled-data
controllers with continuous-time performance objectives (hybrid
systems), specifically, the design and analysis of single- and
multirate control systems in the l1 and H norms. Among the issues
considered are design algorithms and nonconservative conditions for
robustness in time-invariant, time-varying, and/or nonlinear unmodeled
dynamics. The second aspect is to develop systematic and computable
methods for the design of low-order controllers, through various types
of model reduction in conjunction with robust stability and closed-
loop performance analysis.
Optimal and Robust Control Theory and Applications
B. Bamieh,* J. Sreedhar, S. Landry
National Science Foundation, ECS-96-24152
This project deals with mixed continuous/discrete-time systems and
systems with switching nonlinearities systems. We concentrate on
developing a framework in which intersample behavior as well as
quantization and round off error effects can be analyzed, and when
possible, controllers designed. We are also investigating model
reduction and identification of linear parameter varying (LPV)
systems. This identification scheme alleviates the need to perform
many identification experiments for processes whose dynamics may
change with set-point changes.
The Theory of Dynamic Games and Robust Controller Designs
T. Basar*
National Science Foundation, ECS 92-20632
This is a UIUC-INRIA (France) collaborative research project dealing
with fundamental issues in dynamic game theory, with applications in
robust control of nonlinear systems and control of communication
networks.
Optimization-based Robust Identification and Control of Uncertain
Dynamical Systems
T. Basar,* G. Arslan, C. Tang
U.S. Department of Energy, DE-FG02-97ER13939
This program involves fundamental research on optimization-based
robust identification and control of uncertain dynamical systems. The
class of systems considered includes large-scale, stochastic,
nonlinear, hybrid, and distributed parameter systems, all subject to
different types of static as well as dynamic uncertainties. The
optimality criteria adopted include minimax, risk-sensitive, and
receding horizon formulations. The main theme is optimality-based
identification, control, and model simplification under severe
internal and external uncertainties. Research involves not
independent, but a combined design of observer/filter and control
architectures supported by optimization-based model-reduction,
decomposition, and aggregation techniques.
Transportable Agents for Reconfigurable Wireless Networks
T. Basar,* P. R. Kumar,* P. Gupta, O. C. Imer
U.S. Air Force Office of Scientific Research, DC 5-36128
The goal of this project is to develop technologies that will maximize
the usability of complex, global communications networks, especially
wireless networks. The key technologies include: (1) transportable-
agent systems, (2) dynamic stochastic control for agent planning
and network management, and (3) adaptive wireless-network
configuration and routing. Special attention will be paid to the last
two topics.
Intelligent Control of Dynamic Systems
T. Basar,* P. R. Kumar,* W. R. Perkins,* S. Meyn,*
National Science Foundation, ECS 92-16487
This project seeks a new approach to designing complex systems in
which advanced techniques are integrated to produce
"intelligent" systems of superior performance in the
presence of large uncertainties and stringent specifications. The goal
is to translate high-level commands or specifications automatically
into lower level actions on the environment or plant, while fully
utilizing any prior information as well as information contained in
the real-time environmental responses. Multilayer decision models for
control of subsystems with conflicting objectives, decentralized
control, and robust and adaptive control approaches will be developed.
Model Building, Control, and Optimization of Large-Scale Systems
T. Basar,* I. E. Tezcan, C. Tang, M.-Q. Xiao, G. Arslan
U.S. Department of Energy, DE-FG02-94-ER-13939
This project involves fundamental research on the modeling, control,
and optimization of large-scale systems. It encompasses both linear
and nonlinear models, deterministic and stochastic systems with
external and internal uncertainty, systems with weak spatial and weak
or strong informational links, and dynamic decision models with
multiple criteria. The overall goal is the development of new and
effective methodologies for robust control, stabilization and
optimization of large-scale systems in the presence of static as well
as dynamic uncertainty, and the analysis of such systems using
concepts of multimodeling, decomposition, and aggregation.
Adaptive Intelligent Scheduling of ATM Networks
T. Basar,* R. Srikant,* S. Compans
U.S. Air Force, AF SSC SC 1201-UI
Flow controllers are essential components of high-speed (and, in
particular, ATM) networks, designed to guarantee high quality of
services on the one hand and to allow for efficient use of the network
on the other. Such a controller is required to have the capability
that, when other sources transmit, its own transmission rate is
dynamically and adaptively adjusted so as to avoid congestion in the
network, as congestion might result in low throughputs, high delays,
and high rate of losses of packets. When the interfering traffic from
other sources is relatively low, then the controller is expected to
allow a high rate of transmission of information so as to make the
best use of the bandwidth available. The project is devoted to
developing such controllers and analyzing their performance
analytically and through simulations.
Issues in Robust Controller Design and the Theory of Dynamic Games
T. Basar,* M.-Q. Xiao, V. Hsu, R. Maheswaran, S. Compans
National Science Foundation, ECS 93-12807
This project is aimed at developing a comprehensive time-domain-based
theory for the analysis and synthesis of performance-robust minimax
controllers and identifiers for nonlinear systems subject to
deterministic and/or partially stochastic disturbances. The general
approach adopted is that of dynamic or differential game theory, and
in this regard part of the current research is devoted to obtaining
fundamental results on zero-sum and nonzero-sum differential games.
Part of the research activity is also devoted to exploration of the
relationship with stochastic control problems with exponentiated cost,
again from a performance-robustness point of view.
Semiconductor Manufacturing Plants--Design of Efficient Operating
Policies and Performance Analysis
P. R. Kumar*
National Science Foundation, ECS 94-03571
This research addresses the problem of designing efficient scheduling
policies to reduce the mean and variance of cycle-time. Comprehensive
comparative testing of policies on realistic fabrication models is
planned. We also address the problem of performance evaluation of
queueing networks, which arise not only in semiconductor manufacturing
systems, but also in communication networks and computer systems.
Questions of the following type are addressed: Given a system
description, in terms of the number of servers, their up and down time
statistics, the description of the various flows, and parameters such
as throughput rates, routes, and processing times at each server, how
does one predict the performance of the system?
Stochastic Analysis and Control of Manufacturing Systems
P. R. Kumar*
U.S. Army Research Office, DAAH04-95-1-0090
The goal of this project is to develop an applicable theory for
analysis and control of manufacturing systems. Manufacturing systems
are composed of a complex interaction of machines and parts. The
systems are typically large scale and subject to disruptions such as
machine failures. The goal is to control or schedule these systems
efficiently to achieve optimal performance in terms of mean
manufacturing lead time, variance, ability to meet due dates, cost of
work in process, and shortfall costs. The issues are: How does a
specific scheduling policy perform? and How does one synthesize good
scheduling policies?
Analysis of Wafer Fab Operations
P. R. Kumar*
Semiconductor Research Corp.
Wafer fab operations are complex for a variety of reasons: the
reentrant nature of process flows, alternation between batch and
single-wafer processing, set-up times incurred in species or lot type
changes, presence of hot lots, equipment down times, time-varying
yield, nonstationary behavior during ramp-up, demand uncertainties,
capacity phase-in, etc. We will study descriptive issues concerning
performance evaluation of fabs and methodologies for cycle-time
prediction as well as the impact of process times variability, release
policies, priority policies, hot lots, equipment failures, and product
mix. Planning issues concerning yield learning, equipment utilization
over time, effects of adding equipment over time, ramp-up, and
nonstationary behavior will be examined together with industry
participation.
Wafer Fab Operations--Modeling, Analysis, and Design
P. R. Kumar*
National Science Foundation, ECS-97-12923
Operational modeling of semiconductor factories is motivated by three
major trends. First, there is concern about how to maintain the
historical trend of exponentially decreasing cost per function.
Second, capital costs are increasing exponentially. Third, competition
from international sources is increasingly fierce in many segments of
the industry. Together, these factors dictate that all fab operations
be optimized for productivity, cost, and returns to the extent
possible and make it imperative to examine future fab designs with a
view to reducing capital outlays.
New Methods for Performance Evaluation of Broadband Networks and
Multihop Radio Networks
P. R. Kumar,* S. P. Meyn
Joint Services Electronics Program, N00014-96-1-0129
This research is concerned with the development of new methods for
performance evaluation of broadband networks and multihop radio
networks. The key performance issues are the study of delay and
throughput. The new methodology is based on linear programming and
optimization theory. Also studied is the design of wireless networks
in volatile environments.
Systems Design and Analysis--Stability, Performance, and Robustness
S. P. Meyn,* D. Down
National Science Foundation; ECS 94-03742
In this project we consider scheduling policies for large
manufacturing systems and the dynamics of these systems under the
influence of random breakdowns, fluctuations in demand and yield, and
changes in operating conditions.
Adaptive Control of Time-varying Systems
S. P. Meyn,* L. Brown, R. Ravikanth
University of Illinois
We consider generalizations of the least squares algorithm for
identifying time-varying systems and the performance of adaptive
control schemes based upon these estimation algorithms. These
controllers are currently being implemented on an arc welder at the
U.S. Army Construction Engineering Research Laboratory.
Estimation and Stochastic Modeling in Geophysics
Y. Bresler*
Schlumberger-Doll Research
The goal of this research is to develop models, estimation techniques,
and computational algorithms for inverse problems arising in
geophysics, and in particular in reservoir characterization. Although
large volumes of data may be available in these problems, they do not
sufficiently determine the underground structure under study. We are
studying the use of stochastic models and nonlinear constraints to
decrease this uncertainty.
Statistical Techniques in Inverse Problems
Y. Bresler,* G. Harikumar, I. B. Kerfoot
National Science Foundation, MIP 91-57377 PYI
Our goal is to develop optimal techniques and efficient algorithms in
three areas of imaging: (1) image reconstruction from partial
information, (2) acquisition of time-varying images, (3) visualization
of vector fields. We are studying nonlinear techniques for tomographic
with limited angle data, blind image restoration, and for other ill-
posed inverse problems. We are also developing a systematic theory for
designing minimum rate sampling patterns. We are developing algorithms
for segmentation and maximally informative display of vector-valued
images, such as are acquired in multispectral or multimodality remote
sensing and diagnostic imaging. This research has applications in
biomedical imaging; video; remote sensing and surveillance; and
geophysics.
Image Formation from Sparse Data, with Applications
Y. Bresler,* D. C. Munson, Jr.,* P. Feng, J. A. Lee, S. Xiao
Joint Services Electronics Program, N00014-96-1-0129
This project is a fundamental study of imaging from sparse Fourier
data, with an emphasis on 3-D synthetic aperture radar (SAR). In SAR,
as in most other important computed imaging applications, it is often
impossible or prohibitively expensive to collect dense data sets that
completely define the image. Our goal is to explore the use of various
frequency and spatial domain constraints to obtain a unique and stable
solution from sparse data sets. Specifically, our objectives are to
characterize the fundamental limitations of various acquisition and
constraint combinations and to develop efficient algorithms for image
acquisition and formation in these circumstances. The methods will be
validated for the 3-D SAR scenario.
Human-Computer Interaction (HCI)
T. S. Huang,* L. Chen, V. Pavlovic, N. Jojic, S. Chu,
U.S. Army Research Office, DAAL01-96-Z-0003; National Science
Foundation, JRI-9634618; Yamaha Motor Corp.
We use the term HCI in a very broad sense to include communication
between person and computer as well as communication between persons
via computer. An example of the former is a person using a
workstation, an example of the latter is tele-collaboration. We are
investigating a variety of issues related to the use of computer
vision in HCI. These include: facial feature extraction and tracking,
determining 3-D head pose, facial movement modeling, analysis, and
synthesis, hand gesture recognition, human body motion analysis, and
person identification.
Multimedia Databases
T. S. Huang,* S. Mehrotra,* K. Ramchandran,* Y. Rui,
NSF/DARPA/NASA Digital Library Initiative Program under Cooperative
Agreement 94-11318; Defense Advanced Research Projects Agency, N6601-
95-C8511
We are studying a number of challenging issues in image/video data
indexing and retrieval. Of particular interest are similarity-based
retrieval where similarity measures are based on image content such as
color, texture, shape, and layout; mapping of high-level concepts to
low-level image features; and how to deal with data and query
uncertainties.
Image/Video Compression and Representation
T. S. Huang,* K. Ramchandran,* M. Gharavi-Alkhansari, H. Tao, A.
Colmenarez, R. Lopez, S. Servetto
Joint Services Electronics Program, N00014-96-1-0129; Army Research
Laboratory Coop. Agreement DAAL01-96-2-0003
Our goal is to investigate image/video representation and compression
schemes that are suitable for data storage, retrieval, and display.
Performance criteria will be based not only on compression factors,
but also on scalability, interoperability, and ease of manipulation
with compressed data. Under study are fractal coding,
wavelet/morphological coding, and 3-D model-based methods.
Digital Filters with Adaptive Fault Tolerance
W. K. Jenkins,* J. Jiang, C. Schmitz
Joint Services Electronics Program, N00014-96-I-0129
This project investigates how the learning process in adaptive digital
filters is disturbed by hardware failures and how to design filters
and adaptive algorithms that can continue operating in the presence of
such failures. Adaptive systems are capable of adjusting parameters to
reduce a specified error criterion. It has been shown that whenever a
hardware failure occurs that increases the error, the system will
attempt to compensate for this failure by further self-adjustment.
Recently this research has concentrated on compensating broader
classes of hardware errors and on applying adaptive fault tolerance to
adaptive filters of the infinite impulse response class.
Computationally Efficient Algorithms for Adaptive Quadratic Volterra
Filters
W. K. Jenkins,* C. W. Therrien, X. Li
Joint Services Electronics Program, N00014-96-1-0129
The structure of the input autocorrelation matrix in Volterra second-
order adaptive filters for general colored Gaussian input processes
has been analyzed to determine how to best formulate a computationally
efficient, fast adaptive algorithm. It was shown that when the input
signal samples are ordered properly within the input data vector, the
autocorrelation matrix of quadratic filter inherits a block diagonal
structure, with some of the subblocks also having diagonal structure.
Some new results in developing and evaluating computationally
efficient quasi-Newton adaptive algorithms have been obtained that
take advantage of the sparsity and unique structure of the correlation
matrix that results from this formulation.
VLSI Adaptive Equalizers for Equalizing Magnetic Recording Channels
W. K. Jenkins,* I. Li
Joint Services Electronics Program, N00014-96-I-0129
This project is investigating the design of an adaptive equalizer-on-
a-chip for the equalization of magnetic recording channels. A design
based on combining a residue number system architecture with a block
LMS adaptive algorithm is being evaluated for its potential to a
design that achieves sufficiently high operating speeds for magnetic
disk applications, while having simple enough circuit requirements to
be fabricated as a monolithic VLSI component. Special attention is
being devoted to the management of short word length finite precision
arithmetic and its effect on the learning characteristic of the
equalizer. This project involves both VLSI design and fabrication.
Channel Equalization with Adaptive Filtering and the Preconditioned
Conjugate Gradient Algorithm
W. K. Jenkins,* R. A. Soni
Joint Services Electronics Program, N00014-96-1-0129
Communication system performance is often degraded by imperfections of
the channel. When additive noise and nonideal channel characteristics
are unknown prior to transmission, adaptive equalizers are used to
compensate for these imperfections and improve overall performance.
For highly correlated received sequences, the convergence rate of the
equalizer is a strongly limiting factor. This project aims to develop
novel schemes employing preconditioned conjugate gradient (PCG)
optimization for channel equalization. Results have been obtained to
illustrate that, compared to an LMS equalizer, the PCG equalizer
provides significantly improved performance for algorithms which
minimize the mean squared error and constant modulus error criteria.
Adaptive and Optimal Time-Frequency Methods for Nonstationary Signals
D. L. Jones,* M. L. Kramer, B. Krongold, A. Rao, L. Qian
U.S. Office of Naval Research, N00014-95-1-0674
New adaptive and statistically optimal time-frequency analysis methods
are being developed for improved processing of nonstationary signals.
The class of problems for which time-frequency-based detection is
being characterized and optimal kernels for detection are being
derived. New adaptive time-frequency representations for high-
resolution visual characterization of signals are also under
development. These methods are being applied to problems in condition
assessment for machinery monitoring and fault detection, mine
classification, and transient detection and analysis.
Energy Partitioning Using Overdetermined Basis Decompositions
D. L. Jones,* B. Krongold
U.S. Office of Naval Research, N00014-95-1-0907
This research project is developing signal processing methods based on
overdetermined basis decompositions for estimating the relative
energies of individual components of complex signals and for component
separation and recovery. Such an approach can decompose a signal with
multiple overlapped, nonorthogonal components onto different basis
elements, thereby separating them in situations in which standard
filtering approaches or orthogonal basis decompositions cannot.
Research in this area is still in its infancy, and we propose to
further develop the theory behind these methods and to apply them to
the problem of energy partitioning and other promising navy
applications.
Radar Imaging of Runways during Aircraft Landing
D. C. Munson, Jr.,* J. A. Lee
Rockwell International
We are investigating synthetic aperture radar (SAR) as a means of
imaging runways through fog and cloud cover from an approaching
aircraft. Current radars with traditional signal processing are
incapable of providing the resolution required at long ranges, because
of the wide beam widths of the antennas employed. Our approach uses
the changes in angular aspect of points in the airport scene, provided
by the motion of the aircraft, to produce high-resolution imagery from
return signals collected by a conventional radar.
Model-based Tomographic Imaging Methods
Z.-P. Liang,* C. P. Hess
National Science Foundation, BES 95-02121, MIP 94-10463
The mathematical basis of tomographic imaging is conventionally rooted
in the well-established Fourier or radon transform theories, so that
image quality is mainly dependent on how the data space is sampled. In
practice, physical and temporal constraints often prevent a sufficient
coverage of the data space, resulting in various image artifacts, such
as Gibbs ringing, resolution degradation, and various motion effects.
This project is aimed at overcoming these problems by developing new
model-based imaging techniques that can effectively incorporate a
priori information into the imaging process. Application of these
techniques to cardiac imaging and functional brain mapping is also
addressed.
Artificial Neural Networks
Z.-P. Liang,* T. S. Huang,* Y. Zhang, H. Pan
Joint Services Electronics Program, N00014-96-1-0129
The primary goal of this project is to develop new neural network
architectures and learning algorithms useful for multisensory data
fusion, recognition of time-varying patterns, and automatic image
segmentation. To achieve this goal, work is being carried out to
develop a new neuronal model with both regular and modulatory inputs,
a new wavelet-based multichannel network architecture, and a dynamical
system-based learning rule. Practical issues of hybrid processing with
both neural network models and statistical models such as the hidden
Markov model are also being investigated in this project.
Automatic Segmentation of Brain Images
Z.-P. Liang,* J. Ji, Z. Fu
National Science Foundation, BES 94-10463
After two decades of active research, automatic image segmentation
remains one of the most challenging problems in image processing and
computer vision. This project is aimed at developing a prototype
pattern recognition system for automatic segmentation of brain images.
This system contains components for multiscale processing, pattern
generation, and neural network learning. We expect that the
computational principles used in building this system will be useful
for solving other practical pattern recognition problems.
High-Performance Computing for the Electromagnetic Modeling of
Interconnects and Packages
J. E. Schutt-Ainé,* F. Lambrecht
Center for Computational Electromagnetics
The electromagnetic modeling of packages and interconnects plays a
very important role in the design of high-speed digital circuits and
is most efficiently performed by using computer-aided design
algorithms. In the past two decades, researchers in the
electromagnetic and microwave areas have striven to extend the
knowledge of interconnection properties. Presently, algorithms are
available that model complex interconnect structures; however, because
of the extensive computations involved, only portions or subsets of a
whole system are modeled in existing computer-aided design (CAD)
tools. The objective is to assess the computational performance of the
different architectures and the possible implementation of a CAD tool
for interconnects in the supercomputer platform.
Modeling of Interconnections for High-Speed Digital, Microwave, and
Optoelectronics Applications
J. Schutt-Ainé,* K. Coperich, T. Nguyen
National Science Foundation, EEC 95-20964
The electrical performance of high-speed integrated circuit and
digital networks strongly depends on the electromagnetic performance
of interconnects between components of a system. Packaging has become
a critical area in the design of high-speed communications systems and
fast computers. Our purpose is to provide the support technology
necessary for aggressive packaging schemes in the areas of design,
modeling, testing, measurement, and circuit simulation. This will be
achieved by using electromagnetic theory as an analysis tool to yield
a better understanding of interconnect problems. New design ideas will
be studied and evaluated and solutions will be proposed for current
system level integration problems.
Optimum Interconnect Design for High-Speed Digital Applications
J. Schutt-Ainé,* J. Tsai, F. Liu, A. Berger, C. Lestrade
Joint Services Electronics Program, N00014-90-J-1270
The development of efficient and accurate computer-aided design tools
is essential for the implementation of high-speed digital circuits
used in computer systems and communication networks. With current
trends in which network complexity and signal speed keep increasing,
problems associated with signal integrity such as crosstalk,
distortion losses can compromise the overall electrical performance of
computers and communication systems. Presently, industrial needs for
computer support in network design is increasing rapidly; however,
there is a serious lag in the availability of design and analysis
tools capable of handling the complexity and volume of manufactured
systems.
Modeling and Design of High-Speed Interconnects for Optoelectronics
Applications
J. Schutt-Ainé,* K. Coperich, F. Liu
NSF Center for Compound Semiconductor Microelectronics
The objective is to develop a comprehensive approach to the generation
of design guidelines in high-speed optoelectronics communications
requiring use of optical-electronic interfaces that combines modeling
and simulation tools with experimental information. These interfaces
must handle information at gigabit rates within very small dimensions.
At those signal speeds and dimensions, crosstalks and other noise
phenomena cannot be avoided; therefore, they must be properly managed
and controlled with accurate transmission-line simulation and design
tools. Extensive simulation of signal transmission through these
structures can dramatically reduce cost and turnaround time associated
with the manufacturing process. To maintain signal integrity, issues
pertaining to crosstalk and signal reflections must also be addressed.
Nonlinear Modeling of HBTs
J. Schutt-Ainé,* T. Nguyen
Texas Instruments, Inc.
The purpose of the effort is to derive a nonlinear model for
heterojunction bipolar transistors. This will be done by combining
measurement simulation and modeling tools. Since HBT's are not
conventional devices, it is necessary to derive and implement a SPICE
model which later will be transferred to Libra or any other circuit
simulator. Large-signal characteization primarily consists of load-
pull measurements. Because of the importance of large-signal
measurements and because of the complexity of load-pull techniques, a
major portion of the project is devoted to the collection and study of
load-pull data.
CAD Tools for Communication Microsystems
J. Schutt-Ainé,* K. Coperich, J. Tsai
Defense Advanced Research Projects Agency, AF ECE 0849
Recent developments in the area of wireless communication systems and
micro-electro-mechanical systems (MEMS) has enabled the networking of
distributed transducers in a wireless mode. It is now possible to
integrate monolithic microwave integrated circuit (MMIC) front-end
modules with MEMS components such as antennas, switches, and filters.
Our objective is to supply the necessary CAD tools to improve first-
pass success and reduce design iterations for such systems. In
particular, electromagnetic techniques are used to model various MEMS
switch structures and combined with simulation techniques to predict
the transient and steady-state response of these components. The goal
is to reduce the design cycle from several man-years to one man-week
in the successful implementation of these MEMS structures.
Symmetry Concepts in Scattering and Inverse Scattering Problems
W. C. Chew,* K. Radhakrishnan
U.S. Office of Naval Research, N00014-95-I-0872
This research involves finding new algorithms to solve the forward
scattering and inverse scattering problems in electromagnetics.
Symmetry concepts will be exploited to see if redundancies could be
reduced in conventional methods of solving such problems. Of
particular interest is how the translational symmetry and rotational
symmetry of physical laws can be exploited to achieve this purpose.
Moreover, nested principles and equivalence principles will be used to
enhance the speed at which scattering and inverse scattering problems
could be solved on computers.
Inversion of Well-logging Tools
W. C. Chew,* S. Y. Chen
Schlumberger
In this project, we study the use of the distorted Born iterative
method and the local shape function method to study the inversion of
well-logging tools. These new methods can invert a profile of much
higher contrast than conventional technique where a linearization
approximation is made. To expedite the inversion, the forward problem
is solved with the CG-FFHT (conjugate gradient--fast Fourier Hankel
transform) method. Alternatively, a finite-element method with a
frontal solver is also used to invert well-logging data.
Forward and Inverse Modeling for Well-Logging Tools
W. C. Chew,* J. M. Jin,* E. Michielssen,* S. H. Deng,
Mobil
In this project, we study efficient methods to model 3-D geometries
involving lossy inhomogeneous media. We study the use of differential
equation solvers and integral equation solvers to achieve this goal.
Differential equations are solved with the finite-element method,
finite-difference method together with iterative methods like
conjugate gradient method, biconjugate gradient method, and spectral
Lanczos method. Integral equations are solved with method of moments
and the multilevel fast multipole algorithms. These solutions will
help model the response of a well-logging tool in a complex
environment. In the inverse problem, we will apply the Born iterative
and distorted Born iterative method to solve inverse problems related
to well-logging using efficient forward solvers.