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Law K.L.,University of Illinois at Urbana - Champaign | Law K.L.,TU Darmstadt | Do M.N.,Coordinated Science Laboratory | Do M.N.,University of Illinois at Urbana - Champaign
IEEE Transactions on Image Processing | Year: 2011

We study the theory and algorithms of an optimal use of multidimensional signal reconstruction from multichannel acquisition by using a filter bank setup. Suppose that we have an N-channel convolution system, referred to as N analysis filters, in M dimensions. Instead of taking all the data and applying multichannel deconvolution, we first reduce the collected data set by an integer M × M uniform sampling matrix D, and then search for a synthesis polyphase matrix which could perfectly reconstruct any input discrete signal. First, we determine the existence of perfect reconstruction (PR) systems for a given set of finite-impulse response (FIR) analysis filters. Second, we present an efficient algorithm to find a sampling matrix with maximum sampling rate and to find a FIR PR synthesis polyphase matrix for a given set of FIR analysis filters. Finally, once a particular FIR PR synthesis polyphase matrix is found, we can characterize all FIR PR synthesis matrices, and then find an optimal one according to design criteria including robust reconstruction in the presence of noise. © 2011 IEEE.


Yang T.,University of Illinois at Urbana - Champaign | Mehta P.G.,University of Illinois at Urbana - Champaign | Meyn S.P.,Coordinated Science Laboratory
Proceedings of the American Control Conference | Year: 2011

A new formulation of the particle filter for nonlinear filtering is presented, based on concepts from optimal control, and from the mean-field game theory framework of Huang et. al. [8]. The optimal control is chosen so that the posterior distribution of a particle matches as closely as possible the posterior distribution of the true state, given the observations. In the infinite-N limit, the empirical distribution of ensemble particles converges to the posterior distribution of an individual particle. The cost function in this control problem is the Kullback-Leibler (K-L) divergence between the actual posterior, and the posterior of any particle. The optimal control input is characterized by a certain Euler-Lagrange (E-L) equation. A numerical algorithm is introduced and implemented in two general examples: A linear SDE with partial linear observations, and a nonlinear oscillator perturbed by white noise, with partial nonlinear observations. © 2011 AACC American Automatic Control Council.


Paranjape A.A.,University of Illinois at Urbana - Champaign | Chung S.-J.,University of Illinois at Urbana - Champaign | Chung S.-J.,Coordinated Science Laboratory | Kim J.,University of Illinois at Urbana - Champaign
IEEE Transactions on Robotics | Year: 2013

We describe the design of an aerial robot inspired by birds and the underlying theoretical developments leading to novel control and closed-loop guidance algorithms for a perching maneuver. A unique feature of this robot is that it uses wing articulation to control the flight path angle as well as the heading angle. It lacks a vertical tail for improved agility, which results in unstable lateral-directional dynamics. New closed-loop motion planning algorithms with guaranteed stability are obtained by rewriting the flight dynamic equations in the spatial domain rather than as functions of time, after which dynamic inversion is employed. It is shown that nonlinear dynamic inversion naturally leads to proportional-integral-derivative controllers, thereby providing an exact method for tuning the gains. The capabilities of the proposed bioinspired robot design and its novel closed-loop perching controller have been successfully demonstrated with perched landings on a human hand. © 2004-2012 IEEE.


Yin H.,University of Illinois at Urbana - Champaign | Mehta P.G.,University of Illinois at Urbana - Champaign | Meyn S.P.,Coordinated Science Laboratory | Shanbhag U.V.,Enterprise Systems
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010

The purpose of this paper is to understand phase transition in noncooperative dynamic games with a large number of agents. Applications are found in neuroscience, biology, economics, as well as traditional engineering applications. The focus of analysis is a variation of the large population LQG model of Huang et. al. 2007 [6], comprised here of a controlled nonlinear N-dimensional stochastic differential equation model, coupled only through a nonlinear cost function. The states are interpreted as the phase angle for a collection of non-homogeneous oscillators, and in this way the model may be regarded as an extension of the classical coupled oscillator model of Kuramoto. A deterministic PDE model is proposed, which is shown to approximate the stochastic system as the population size approaches infinity. Key to the analysis of the PDE model is the existence of a particular Nash equilibrium in which the agents 'opt out' of the game, setting their controls to zero, resulting in the 'incoherence' equilibrium. Methods from dynamical systems theory are used in a bifurcation analysis, based on a linearization of the PDE model about the incoherence equilibrium. A critical value of the control cost parameter is identified: Above this value, the oscillators are incoherent; and below this value (when control is sufficiently cheap) the oscillators synchronize. These conclusions are illustrated with results from numerical experiments. © 2010 AACC.


Kadloor S.,Coordinated Science Laboratory | Kadloor S.,University of Illinois at Urbana - Champaign | Kiyavash N.,Coordinated Science Laboratory | Kiyavash N.,University of Illinois at Urbana - Champaign | Venkitasubramaniam P.,Lehigh University
Proceedings - IEEE INFOCOM | Year: 2012

In this work, we study information leakage in timing side channels that arise in the context of shared event schedulers. Consider two processes, one of them an innocuous process (referred to as Alice) and the other a malicious one (referred to as Bob), using a common scheduler to process their jobs. Based on when his jobs get processed, Bob wishes to learn about the pattern (size and timing) of jobs of Alice. Depending on the context, knowledge of this pattern could have serious implications on Alice's privacy and security. For instance, shared routers can reveal traffic patterns, shared memory access can reveal cloud usage patterns, and suchlike. We present a formal framework to study the information leakage in shared resource schedulers using the pattern estimation error as a performance metric. In this framework, a uniform upper bound is derived to benchmark different scheduling policies. The first-come-first-serve scheduling policy is analyzed, and shown to leak significant information when the scheduler is loaded heavily. To mitigate the timing information leakage, we propose an "Accumulate-and-Serve" policy which trades in privacy for a higher delay. The policy is analyzed under the proposed framework and is shown to leak minimum information to the attacker, and is shown to have comparatively lower delay than a fixed scheduler that preemptively assigns service times irrespective of traffic patterns. © 2012 IEEE.


Narayanan S.,Coordinated Science Laboratory | Varatkar G.V.,Qualcomm | Jones D.L.,Coordinated Science Laboratory | Shanbhag N.R.,Coordinated Science Laboratory
IEEE Transactions on Signal Processing | Year: 2010

Traditional integrated circuit design achieves error-free operation by designing with margins (clock frequency and supply voltage) and/or including hardware replication and recomputation, which may counter the full energy and area benefits of aggressive technology scaling. It is thus desirable that modern systems-on-chip (SoCs) permit hardware errors while maintaining robust system-level performance. Treating hardware errors as computational noise and extending traditional estimation theory to include practical SoC design constraints yields a novel and general design optimization framework. This work demonstrates the breadth of applicability of the estimation-theoretic framework for system design by showcasing two different application classes that demonstrate 36% to 50% power reduction. © 2010 IEEE.


News Article | February 15, 2017
Site: www.prweb.com

David C. Munson Jr. has been named Rochester Institute of Technology’s 10th president. The RIT Board of Trustees made the decision at a special session, selecting the former dean of the University of Michigan College of Engineering from a pool of national candidates. Munson will assume RIT’s top post July 1, succeeding Bill Destler, RIT’s president since 2007. Munson will be responsible for one of the nation’s leading research and career-oriented universities featuring 18,700 students from all 50 states and more than 100 foreign countries, 121,000 alumni, $73 million in sponsored research, and an endowment of more than $750 million. “It is a great honor and privilege to become the next president of what I believe to be a gem in higher education,” said Munson. “I was drawn to RIT when I observed an exciting portfolio of academic programs, research with impact to solve global problems, and an ability to stay focused on the overall student experience. I was truly impressed with RIT’s strengths in the arts, as well as technology, and how they are blended. I look forward to maintaining university traditions and simultaneously building on the 2025 Strategic Plan, ‘Greatness through Difference.’ I am eager to meet members of the RIT community and work with them to reach their aspirations.” A 24-member search committee composed of students, faculty, staff, alumni, administration and trustees narrowed the pool of candidates before the final selection by the Board of Trustees. “We are proud to welcome Dr. Munson to RIT and look forward to him leading the university through its next exciting chapter,” said Christine Whitman, chair of the RIT Board of Trustees. “His extensive academic experience, respected research credentials, demonstrated leadership, engagement with students and global vision will propel RIT to new heights. We know he will build on the strong foundation established by President Destler and his predecessors whose tireless work made RIT a distinctly great university.” Whitman added: “Dr. Munson has articulated a vision that is consistent with our strategic plan. He has the skills and experience to accomplish our goals and he sees opportunities to take us even further.” Munson has 38 years of experience in higher education, which includes serving as the Robert J. Vlasic Dean of Engineering at Michigan from 2006 to 2016, where he served two five-year terms, the maximum allowed by U-M. Michigan Engineering is considered one of the top engineering schools in the world. Eight of its academic departments are ranked in the nation’s top 10. Munson earned his BS degree in electrical engineering (with distinction) from the University of Delaware in 1975. He earned an MS and MA in electrical engineering from Princeton in 1977, followed by a Ph.D. in electrical engineering in 1979, also from Princeton. From 1979 to 2003, Munson was with the University of Illinois, where he was the Robert C. MacClinchie Distinguished Professor of Electrical and Computer Engineering, Research Professor in the Coordinated Science Laboratory, and a faculty member in the Beckman Institute for Advanced Science and Technology. In 2003, he became chair of the Department of Electrical Engineering and Computer Science at U-M prior to becoming dean. Today, with his deanship appointment fulfilled, he serves as a professor of electrical engineering and computer science. Munson’s teaching and research interests are in the area of signal and image processing. His current research is focused on radar imaging and computer tomography. He is co-founder of InstaRecon Inc., a start-up firm to commercialize fast algorithms for image formation in computer tomography. He is affiliated with the Infinity Project, where he is coauthor of a textbook on the digital world, which has been used in hundreds of high schools nationwide to introduce students to engineering. Munson is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE), a past president of the IEEE Signal Processing Society, founding editor-in-chief of the IEEE Transactions on Image Processing, and co-founder of the IEEE International Conference on Image Processing. In addition to multiple teaching awards and other honors, he was presented the Society Award of the IEEE Signal Processing Society, he served as a Distinguished Lecturer of the IEEE Signal Processing Society, he received an IEEE Third Millennium Medal, and he was the Texas Instruments Distinguished Visiting Professor at Rice University. In 2016, Munson earned the Benjamin Garver Lamme Medal from the American Society of Engineering Education (highest award for an engineering administrator). It is this record of accomplishment that drew praise from current RIT President Bill Destler, who will retire June 30 after serving more than 40 years in higher education and 10 years as RIT president. He applauded the work of the search committee and the selection of the new president. “On behalf of RIT and the Greater Rochester-Finger Lakes region, I welcome Dr. Munson and his wife, Nancy, to our community,” said Destler. “The naming of a new president is an exciting time for RIT students, faculty and staff, as well as our alumni, family and friends around the world. Dr. Munson has an impressive record of accomplishments, and brings skills, expertise and experience that will greatly benefit this university, and further propel RIT as one of the great global universities.” To learn more about Munson’s credentials, including a curriculum vitae, go to: http://www.rit.edu/presidentialsearch/ To read more about the search process, go to http://www.rit.edu/news/story.php?id=59131. To read more about Munson, go to http://www.rit.edu/news/story.php?id=59171. Rochester Institute of Technology is home to leading creators, entrepreneurs, innovators and researchers. Founded in 1829, RIT enrolls about 19,000 students in more than 200 career-oriented and professional programs, making it among the largest private universities in the U.S. The university is internationally recognized and ranked for academic leadership in business, computing, engineering, imaging science, liberal arts, sustainability, and fine and applied arts. RIT also offers unparalleled support services for deaf and hard-of-hearing students. The cooperative education program is one of the oldest and largest in the nation. Global partnerships include campuses in China, Croatia, Dubai and Kosovo. For news, photos and videos, go to http://www.rit.edu/news.


Touri B.,Coordinated Science Laboratory | Nedic A.,Enterprise Systems
Automatica | Year: 2012

We study the ergodicity of backward product of stochastic and doubly stochastic matrices by introducing the concept of absolute infinite flow property. We show that this property is necessary for ergodicity of any chain of stochastic matrices, by defining and exploring the properties of a rotational transformation for a stochastic chain. Then, we establish that the absolute infinite flow property is equivalent to ergodicity for doubly stochastic chains. Furthermore, we develop a rate of convergence result for ergodic doubly stochastic chains. We also investigate the limiting behavior of a doubly stochastic chain and show that the product of doubly stochastic matrices is convergent up to a permutation sequence. Finally, we apply the results to provide a necessary and sufficient condition for the absolute asymptotic stability of a discrete linear inclusion driven by doubly stochastic matrices. © 2012 Published by Elsevier Ltd.


News Article | March 10, 2016
Site: www.cemag.us

Light and electrons interact in a complex dance within fiber optic devices. A new study by University of Illinois engineers found that in the transistor laser, a device for next-generation high-speed computing, the light and electrons spur one another on to faster switching speeds than any devices available. Milton Feng, the Nick Holonyak Jr. Emeritus Chair in electrical and computer engineering, found the speed-stimulating effects with graduate students Junyi Qiu and Curtis Wang and Holonyak, the Bardeen Emeritus Chair in electrical and computer engineering and physics. The team published its results in the Journal of Applied Physics. As big data become bigger and cloud computing becomes more commonplace, the infrastructure for transferring the ever-increasing amounts of data needs to speed up, Feng says. Traditional technologies used for fiber optic cables and high-speed data transmission, such as diode lasers, are reaching the upper end of their switching speeds, Feng says. “You can compute all you want in a data center. However, you need to take that data in and out of the system for the user to use,” Feng says. “You need to transfer the information for it to be useful, and that goes through these fiber optic interconnects. But there is a fundamental switching limitation of the diode laser used. This technology, the transistor laser, is the next-generation technology, and could be a hundred times faster.” Diode lasers have two ports: an electrical input and a light output. By contrast, the transistor laser has three ports: an electrical input, and both electrical and light outputs. The three-port design allows the researchers to harness the intricate physics between electrons and light. For example, the fastest way for current to switch in a semiconductor material is for the electrons to jump between bands in the material in a process called tunneling. Light photons help shuttle the electrons across, a process called photon-assisted tunneling, making the device much faster. In the latest study, Feng’s group found that not only does photon-assisted tunneling occur in the transistor laser, but that it in turn stimulates the photon absorption process within the laser cavity, making the optical switching in the device even faster and allowing for ultra-high-speed signal modulation. “The collector can absorb the photon from the laser for very quick tunneling, so that becomes a direct-voltage-modulation scheme, much faster than using current modulation,” Feng says. “We also proved that the stimulated photon-assisted tunneling process is much faster than regular photon-assisted tunneling. Previous engineers could not find this because they did not have the transistor laser. With just a diode laser, you cannot discover this. “This is not only proving the scientific point, but it’s very useful for high-speed device modulation. We can directly modulate the laser into the femtosecond range. That allows a tremendous amount of energy-efficient data transfer,” Feng says. The researchers plan to continue to develop the transistor laser and explore its unique physics while also forming industry partnerships to commercialize the technology for energy-efficient big data transfer. The Air Force Office of Scientific Research supported this work. Feng also is associated with the Micro and Nano Technology Laboratory and the Coordinated Science Laboratory at the U. of I.


News Article | March 10, 2016
Site: www.nanotech-now.com

Abstract: Light and electrons interact in a complex dance within fiber optic devices. A new study by University of Illinois engineers found that in the transistor laser, a device for next-generation high-speed computing, the light and electrons spur one another on to faster switching speeds than any devices available. Milton Feng, the Nick Holonyak Jr. Emeritus Chair in electrical and computer engineering, found the speed-stimulating effects with graduate students Junyi Qiu and Curtis Wang and Holonyak, the Bardeen Emeritus Chair in electrical and computer engineering and physics. The team published its results in the Journal of Applied Physics. As big data become bigger and cloud computing becomes more commonplace, the infrastructure for transferring the ever-increasing amounts of data needs to speed up, Feng said. Traditional technologies used for fiber optic cables and high-speed data transmission, such as diode lasers, are reaching the upper end of their switching speeds, Feng said. “You can compute all you want in a data center. However, you need to take that data in and out of the system for the user to use,” Feng said. “You need to transfer the information for it to be useful, and that goes through these fiber optic interconnects. But there is a fundamental switching limitation of the diode laser used. This technology, the transistor laser, is the next-generation technology, and could be a hundred times faster.” Diode lasers have two ports: an electrical input and a light output. By contrast, the transistor laser has three ports: an electrical input, and both electrical and light outputs. The three-port design allows the researchers to harness the intricate physics between electrons and light. For example, the fastest way for current to switch in a semiconductor material is for the electrons to jump between bands in the material in a process called tunneling. Light photons help shuttle the electrons across, a process called photon-assisted tunneling, making the device much faster. In the latest study, Feng’s group found that not only does photon-assisted tunneling occur in the transistor laser, but that it in turn stimulates the photon absorption process within the laser cavity, making the optical switching in the device even faster and allowing for ultra-high-speed signal modulation. “The collector can absorb the photon from the laser for very quick tunneling, so that becomes a direct-voltage-modulation scheme, much faster than using current modulation,” Feng said. “We also proved that the stimulated photon-assisted tunneling process is much faster than regular photon-assisted tunneling. Previous engineers could not find this because they did not have the transistor laser. With just a diode laser, you cannot discover this. “This is not only proving the scientific point, but it’s very useful for high-speed device modulation. We can directly modulate the laser into the femtosecond range. That allows a tremendous amount of energy-efficient data transfer,” Feng said. The researchers plan to continue to develop the transistor laser and explore its unique physics while also forming industry partnerships to commercialize the technology for energy-efficient big data transfer. The Air Force Office of Scientific Research supported this work. Feng also is associated with the Micro and Nano Technology Laboratory and the Coordinated Science Laboratory at the U. of I. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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