- Date & Time: Wednesday, August 1, 2012; 12:00 PM
Speaker: Prof. Prashant Mehta, University of Illinois at Urbana-Champaign
MERL Host: Scott A. Bortoff Abstract - In my talk, I will present a self-contained introduction to nonlinear filtering, and describe some recent developments. Specifically, I will introduce the feedback particle filter and show how it admits an innovations error-based feedback control structure. The control is chosen so that the posterior distribution of any particle matches the posterior distribution of the true state given the observations. The subject of my talk is a new formulation of nonlinear filter (for Bayesian inference) that is based on concepts from optimal control and mean-field game theory. Nonlinear filtering is important to many applications in engineering, biology, economics, atmospheric sciences and neuroscience. Several applications will be described to illustrate the theoretical concepts.
This is joint work with Tao Yang and Sean Meyn at the University of Illinois.
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- Date & Time: Friday, July 27, 2012; 12:00 PM
Speaker: Mingyuan Zhou, Duke University
MERL Host: Dehong Liu Abstract - Bayesian nonparametrics, using stochastic processes as prior distributions, is a relatively young and rapidly growing research area in statistics and machine learning. In this talk, we first briefly review completely random measures, a family of pure-jump non-negative stochastic processes that are simple to construct and amenable for posterior computation. We then present nonparametric Bayesian latent variable models based on the beta process, Bernoulli process, gamma process, Poisson process, and in particular, the negative binomial process. Specifically, for continuous data, we discuss dictionary learning with the beta-Bernoulli process and dependent hierarchical beta process, and for count data, we present the beta-negative binomial process and Poisson factor analysis. Furthermore, we discuss how the seeming disjoint count and mixture modelings can be united under the negative binomial processes framework, providing new opportunities to build mixture and hierarchical mixture models with better data fitting, more efficient inference and more flexible model constructions. We show successful applications of our nonparametric Bayesian latent variable models to image processing, topic modeling and count data analysis.
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- Date: July 24, 2012
Where: IEEE Transactions on Information Forensics and Security
MERL Contact: Ye Wang
Research Area: Information Security
Brief - The article "A Theoretical Analysis of Authentication, Privacy, and Reusability Across Secure Biometric Systems" by Wang, Y., Rane, S., Draper, S.C. and Ishwar, P. was published in IEEE Transactions on Information Forensics and Security.
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- Date: July 24, 2012
Where: International Journal of Robust and Nonlinear Control
MERL Contact: Stefano Di Cairano
Research Area: Control
Brief - The article "Model Predictive Control Approach for Guidance of Spacecraft Rendezvous and Proximity Maneuvering" by Di Cairano, S., Park, H. and Kolmanovsky, I. was published in International Journal of Robust and Nonlinear Control.
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- Date: July 22, 2012
Where: IEEE International Geoscience and Remote Sensing Symposium (IGARSS)
MERL Contacts: Dehong Liu; Petros T. Boufounos
Research Areas: Digital Video, Computational Sensing
Brief - The paper "Pan-Sharpening with Multi-scale Wavelet Dictionary" by Liu, D. and Boufounos, P.T. was presented at the IEEE International Geoscience and Remote Sensing Symposium (IGARSS).
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- Date: Thursday, July 19, 2012
Speaker: Rick Vaccaro, University of Rhode Island
MERL Host: Scott A. Bortoff Abstract - The ability to directly specify the closed-loop poles of a multivariable control system is a major benefit of pole-placement algorithms for calculating state-feedback and observer gains. The drawback of these algorithms is the lack of any guarantee on the stability robustness of the resulting control system. The optimal control approach for calculating state-feedback gains (LQR) has a certain guaranteed robustness, but adding an observer (i.e. Kalman filter, LQG) can result in arbitrarily poor robustness. In this talk, a new pole-placement approach is introduced for calculating state-feedback and observer gains. The new approach optimizes robustness and gives impressive results, particularly for output feedback, observer-based control systems.
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- Date: July 16, 2012
Where: International Refrigeration and Air conditioning Conference at Purdue
MERL Contacts: Christopher R. Laughman; Daniel N. Nikovski Brief - The papers "Fast Refrigerant Property Calculations Using Interpolation-Based Methods" by Laughman, C.R., Zhao, Y. and Nikovski, D. and "Extremum Seeking Control for Energy Optimization of Vapor Compression Systems" by Burns, D.J. and Laughman, C. were presented at the International Refrigeration and Air conditioning Conference at Purdue.
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- Date & Time: Monday, July 16, 2012; 2:00 PM
Speaker: Dr. Karl Iagnemma, Director, MIT Robotic Mobility Group
MERL Host: Stefano Di Cairano Abstract - Operator error is a significant factor in a majority of manned and unmanned vehicle accidents. In this talk, a framework for semi-autonomous vehicle accident avoidance will be presented that has been shown to effectively mitigate collisions caused by operator error. The framework analyzes sensor data (from vision and/or LIDAR data) to identify "no go" regions in the environment, and automatically synthesize constraints on vehicle position. An optimal trajectory and associated control inputs are then found via linear or nonlinear model predictive control. The "threat" to the vehicle is quantified from various metrics computed over the optimal trajectory. A number of approaches for arbitrating between operator and control system authority, based on the predicted threat, will be discussed. Extensive simulation and experimental testing will be described for both manned and unmanned scenarios. Future directions in threat assessment and semi-autonomous control, based on the integration of vision-based sensing and active steering control, will also be discussed.
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- Date & Time: Tuesday, July 10, 2012; 11:00 AM
Speaker: Prof Vineet Kamat, University of Michigan
Research Area: Computer Vision
Abstract - This talk will present ongoing research at the University of Michigan Laboratory for Interactive Visualization in Engineering (LIVE) that is exploring applications of mobile pervasive computing and visualization in design, engineering, and construction. Findings from three specific research projects will be presented: Interactive Visualization of Construction Operations in Mobile Outdoor Augmented Reality; Rapid Building Damage Evaluation using Augmented Reality and Structural Simulation; and Location-Aware Contextual Information Access and Retrieval for Rapid On-Site Decision Making. In each case, the development of fundamental algorithms, their implementation as reusable and modular software, and their implementation in the engineering applications will be described.
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- Date: July 9, 2012
Where: IEEE International Conference on Multimedia and Expo (ICME)
Research Area: Information Security
Brief - The paper "A Distance-sensitive Attribute Based Cryptosystem for Privacy-Preserving Querying" by Sun, W. and Rane, S. was presented at the IEEE International Conference on Multimedia and Expo (ICME).
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- Date & Time: Friday, July 6, 2012; 12:00 PM
Speaker: Zixiang Xiong, Texas A&M University
MERL Host: Anthony Vetro Abstract - Driven by a host of emerging applications, distributed source coding has assumed renewed interest in the past decade. Although the Slepian-Wolf theorem has been known for almost 40 years and progresses have been made recently on the rate region of quadratic Gaussian two-terminal source coding, finding the sum-rate bound of quadratic Gaussian multiterminal source coding with more than two terminals is still an open problem. In this talk, I'll briefly go over existing results on distributed source coding problems before describing a set of new results we obtained recently.
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- Date: Tuesday, July 3, 2012
Speaker: Prof. Volkan Cevher, EPFL
MERL Host: Petros T. Boufounos Abstract - Many natural and man-made signals exhibit a few degrees of freedom relative to their dimension due to natural parameterizations or constraints. The inherent low-dimensional structure of such signals are mathematically modeled via combinatorial and geometric concepts, such as sparsity, unions-of-subspaces, or spectral sets, and are now revolutionizing the way we address linear inverse problems from incomplete data.
In this talk, we describe a set of structured sparse models for constrained linear inverse problems that feature exact and epsilon-approximate projections in polynomial time. We pay particular attention to the sparsity models based on matroids, multi-knapsack, and clustering as well as spectrally constrained models. We then study sparse projections onto convex sets, such as the (general) simplex, and ell-1,2,inf balls. Finally, we describe a hybrid optimization framework which explicitly leverages these non-convex models along with additional convex constraints to obtain better recovery performance in compressive sensing, learn interpretable sparse densities from finite samples, and improved sparse Markowitzs portfolios with better return/cost performance.
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- Date: July 1, 2012
Where: IEEE International Symposium on Information Theory (ISIT)
MERL Contacts: Philip V. Orlik; Toshiaki Koike-Akino Brief - The papers "Rateless Feedback Codes" by Sorensen, J.H., Koike-Akino, T. and Orlik, P. and "Ripple Design of LT Codes for AWGN Channel" by Sorensen, J.H., Koike-Akino, T., Orlik, P., Ostergaard, J. and Popovski, P. were presented at the IEEE International Symposium on Information Theory (ISIT).
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- Date & Time: Friday, June 29, 2012; 2:30 PM
Speaker: Prof. Marc Pollefeys, ETH Zurich and UNC Chapel Hill
Research Area: Computer Vision
Abstract - One of the fundamental problems of computer vision is to extract 3D shape and motion from images. This can be achieved when a scene or object is observed from different viewpoints or over a period of time. First, we will discuss image-based 3D modeling and localization in large environments, e.g. urban 3D reconstruction from vehicle-borne cameras and (geo)localization from mobile-phone images. In this context, we will discuss some of the challenges an opportunities offered by symmetries of architectural structures. We will also discuss how changes in an urban environment can be detected from images, leading to the possibility to efficiently acquire 4D models. In addition to explicit 4D modeling of an event, we'll consider the possibility to perform interactive video-based rendering from casually captured videos.
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- Date: June 28, 2012
Where: International Conference on Enterprise Information Systems (ICEIS)
MERL Contact: Daniel N. Nikovski
Research Area: Data Analytics
Brief - The paper "Bayesian Networks for Matcher Composition in Automatic Schema Matching" by Nikovski, D., Esenther, A., Ye, X., Shiba, M. and Takayama, S. was presented at the International Conference on Enterprise Information Systems (ICEIS).
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- Date & Time: Wednesday, June 27, 2012; 12:00 PM - 1:30 PM
Location: Montreal, Canada
MERL Contact: Scott A. Bortoff Brief - In this session, MERL researcher Scott Bortoff will describe Mitsubishi Electric Corporation (MELCO)'s businesses, discuss mechatronics and controls research at MERL and describe opportunities for collaboration and employment. Areas of current research interest include optimal control especially of nonlinear and hybrid systems, model predictive control, nonlinear dynamical systems, and modeling and control of multi-physical heterogeneous systems. Research projects at MERL typically address fundamental problems that are industrially-motivated, and involve application of advanced control theory or dynamical systems theory to MELCO products resulting in new technology that is transferred into the corporate R&D laboratories for subsequent product development. Areas of current application include elevators, HVAC, power generation and distribution, satellites, robot manipulation, servo systems and laser processing systems. MERL has a tradition of open collaboration and hosts visitors and interns especially during the summer months when our population increases by 50%. Researchers and students who have an interest in collaboration, visits, sabbatical leaves or permanent employment are invited.
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- Date: Wednesday, June 27, 2012 - Friday, June 29, 2012
Location: Montreal, Canada Brief - MERL is a sponsor for ACC 2012, the 2012 American Control Conference.
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- Date: June 27, 2012
Where: Optics Express
MERL Contacts: Toshiaki Koike-Akino; Kieran Parsons
Research Areas: Communications, Signal Processing
Brief - The article "High-order Statistical Equalizer for Nonlinearity Compensation in Dispersion-managed Coherent Optical Communications" by Koike-Akino, T., Duan, C., Parsons, K., Kojima, K., Yoshida, T., Sugihara, T. and Mizuochi, T. was published in Optics Express.
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- Date: June 27, 2012
Where: American Control Conference (ACC)
MERL Contacts: Stefano Di Cairano; Scott A. Bortoff Brief - The papers "Further Developments and Applications of Network Reference Governor for Constrained Systems" by Di Cairano, S. and Kolmanovsky, I.V. and "Load Positioning in the Presence of Base Vibrations" by Shilpiekandula, V., Bortoff, S.A., Barnwell, J.C. and El Rifai, K. were presented at the American Control Conference (ACC).
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- Date & Time: Tuesday, June 26, 2012; 12:00 PM
Speaker: Min Sun, University of Michigan
Research Area: Computer Vision
Abstract - Robust human pose estimation is a challenging problem in computer vision in that body part configurations are often subject to severe deformations and occlusions. Moreover, efficient pose estimation is often a desirable requirement in many applications. The trade-off between accuracy and efficiency has been explored in a large number of approaches. On the one hand, models with simple representations (like tree or star models) can be efficiently applied in pose estimation problems. However, these models are often prone to body part misclassification errors. On the other hand, models with rich representations (i.e., loopy graphical models) are theoretically more robust, but their inference complexity may increase dramatically. In this talk, we present an efficient and exact inference algorithm based on branch-and-bound to solve the human pose estimation problem on loopy graphical models. We show that our method is empirically much faster (about 74 times) than the state-of-the-art exact inference algorithm [Sontag et al. UAI'08]. By extending a state-of-the-art tree model [Sapp et al. ECCV'10] to a loopy graphical model, we show that the estimation accuracy improves for most of the body parts (especially lower arms) on popular datasets such as Buffy [Ferrari et al. CVPR'08] and Stickmen [Eichner and Ferrari BMVC'09] datasets. Our method can also be used to exactly solve most of the inference problems of Stretchable Models [Sapp et al. CVPR'11] on video sequences (which contains a few hundreds of variables) in just a few minutes. Finally, we show that the novel inference algorithm can potentially be used to solve human behavior understanding and biological computation problems.
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- Date & Time: Monday, June 25, 2012; 10:30 AM
Speaker: Prof. Toshiyuki Ohtsuka, Osaka University
MERL Host: Stefano Di Cairano Abstract - In this talk, a real-time algorithm for nonlinear model predictive control and its applications will be introduced. The continuation method is combined with an efficient linear solver GMRES to trace the time-dependent optimal solution without iterative searches. Applications of the algorithm include position control of an underactuated hovercraft, route tracking of a ship with redundant actuators, and path generation for an automobile. Automatic code generation by symbolic computation and other related topics will also be introduced.
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- Date: June 16, 2012
Where: IEEE Conference on Computer Vision and Pattern Recognition (CVPR)
Research Area: Computer Vision
Brief - The papers "Connecting the Dots in Multi-Class Classification: From Nearest Subspace to Collaborative Representation" by Chi, Y. and Porikli, F., "Decomposing Global Light Transport using Time of Flight Imaging" by Wu, D., O'Toole, M., Velten, A., Agrawal, A. and Raskar, R., "Changedetection.net: A New Change Detection Benchmark Dataset" by Goyette, N., Jodoin, P.-M., Porikli, F., Konrad, J. and Ishwar, P. and "A Theory of Multi-Layer Flat Refractive Geometry" by Agrawal, A., Ramalingam, S., Taguchi, Y. and Chari, V. were presented at the IEEE Conference on Computer Vision and Pattern Recognition (CVPR).
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- Date: June 10, 2012
Where: IEEE International Conference on Communications (ICC)
MERL Contact: Philip V. Orlik
Research Area: Signal Processing
Brief - The paper "Non-coherent ToA Estimation for UWB Multipath Channels using Max-eigenvalue Detection" by Shi, W., Annavajjala, R., Orlik, P.V., Molisch, A.F., Ochiari, M. and Taira, A. was presented at the IEEE International Conference on Communications (ICC).
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- Date: June 4, 2012
Where: CIRP Conference on High Performance Cutting
Research Area: Computer Vision
Brief - The paper "Offline Force Control and Feedrate Scheduling for Complex Free Form Surfaces in 5-Axis Milling" by Layegh, S.E., Erdim, H. and Lazoglu, I. was presented at the CIRP Conference on High Performance Cutting.
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- Date: June 1, 2012
Where: Computer-Aided Design
Research Area: Computer Vision
Brief - The article "High Accuracy NC Milling Simulation Using Composite Adaptively Sampled Distance Fields" by Sullivan, A., Erdim, H., Perry, R.N. and Frisken, S.F. was published in Computer-Aided Design.
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