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18th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, KDD 2012

作者： Yang, Sen Yuan, Lei Lai, Ying-Cheng Shen, Xiaotong Wonka, Peter Ye, Jieping Computer Science and Engineering Arizona State University Tempe AZ 85287 United States Center for Evolutionary Medicine and Informatics Biodesign Institute Arizona State University Tempe AZ 85287 United States Electrical Engineering Arizona State University Tempe AZ 85287 United States School of Statistics University of Minnesota Minneapolis MN 55455 United States

ISBN: (纸本)9781450314626

High-dimensional regression/classification continues to be an important and challenging problem, especially when features are highly correlated. Feature selection, combined with additional structure information on the features has been considered to be promising in promoting regression/classification performance. Graph-guided fused lasso (GFlasso) has recently been proposed to facilitate feature selection and graph structure exploitation, when features exhibit certain graph structures. However, the formulation in GFlasso relies on pairwise sample correlations to perform feature grouping, which could introduce additional estimation bias. In this paper, we propose three new feature grouping and selection methods to resolve this issue. The first method employs a convex function to penalize the pairwise l∞ norm of connected regression/classification coefficients, achieving simultaneous feature grouping and selection. The second method improves the first one by utilizing a non-convex function to reduce the estimation bias. The third one is the extension of the second method using a truncated l1 regularization to further reduce the estimation bias. The proposed methods combine feature grouping and feature selection to enhance estimation accuracy. We employ the alternating direction method of multipliers (ADMM) and difference of convex functions (DC) programming to solve the proposed formulations. Our experimental results on synthetic data and two real datasets demonstrate the effectiveness of the proposed methods. © 2012 ACM.

关键词： Undirected graphs

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Maximum likelihood based sparse and distributed conjoint analysis

Maximum likelihood based sparse and distributed conjoint ana...

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IEEE/SP Workshop on Statistical Signal Processing (SSP)

作者： Efthymios Tsakonas Joakim Jaldén Nicholas D. Sidiropoulos Bjorn Ottersten ACCESS Linnaeus Centre Royal Institute of Technology Stockholm Sweden Department of Electrical and Computer Engineering University of Minnesota Minneapolis USA Interdisciplinary Centre for Security Reliability and Trust University of Luxembourg Luxembourg

A new statistical model for choice-based conjoint analysis is proposed. The model uses auxiliary variables to account for outliers and to detect the salient features that influence decisions. Unlike recent classification-based approaches to choice-based conjoint analysis, a sparsity-aware maximum likelihood (ML) formulation is proposed to estimate the model parameters. The proposed approach is conceptually appealing, mathematically tractable, and is also well-suited for distributed implementation. Its performance is tested and compared to the prior state-of-art using synthetic as well as real data coming from a conjoint choice experiment for coffee makers, with very promising results.

关键词： Support vector machines Maximum likelihood estimation Vectors Mathematical model Data models Robustness Educational institutions

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Application of an integrated PHY and MAC layer model for half-duplex IEEE 802.15.4 networks to smart grids 11

Application of an integrated PHY and MAC layer model for hal...

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4th International Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL'11

作者： Talha, Batool Di Marco, Piergiuseppe Kaveh, Mostafa Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN United States ACCESS Linnaeus Centre Electrical Engineering Royal Institute of Technology Stockholm Sweden

ISBN: (纸本)9781450309134

This paper puts the spotlight on the home/building area network of the smart grid. The IEEE 802.15.4 standard provides the core infrastructure for collecting data from customers' premises and forwarding it to the operations as well as service providers. An integrated physical (PHY) and medium access control (MAC) layer analytical model is introduced for half-duplex IEEE 802.15.4 networks. The PHY layer propagation channel is modeled as the composite path-loss K distribution while accommodating groundwave propagation, multipath fading, and shadowing. The MAC layer model caters for the unslotted carrier sense multiple access with collision avoidance (CSMA/CA) of IEEE 802.15.4 with unsaturated traffic conditions. Closed-form expressions are derived for the probability density function (PDF) of the instantaneous received power and the average outage probability. The packet success probability without and with capture effect is thoroughly studied for several environments as well as propagation scenarios. The correctness of all analytical results is validated through simulations. © 2011 ACM.

关键词： Carrier sense multiple access

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Characterizing the memory of the GAL regulatory network in Saccharomyces cerevisiae

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Systems and Synthetic Biology 2011年第3-4期5卷 97-104页

作者： Kulkarni, Vishwesh V. Kareenhalli, Venkatesh Viswananthan, Ganesh A. Riedel, Marc Department of Electrical Engineering Indian Institute of Technology Bombay Mumbai 400 076 India Department of Chemical Engineering Indian Institute of Technology Bombay Mumbai 400 076 India Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN 55455 United States

Genetic regulatory networks respond dynamically to perturbations in the intracellular and extracellular environments of an organism. The GAL system in the yeast Saccharomyces cerevisiae has evolved to utilize galactose as an alternative carbon and energy source, in the absence of glucose in the environment. We present a dynamic model for GAL system in Saccharomyces cerevisiae, which includes a novel mechanism for Gal3p activation upon induction with galactose. The modification enables the model to simulate the experimental observation that in absence of galactose, oversynthesis of Gal3p can also induce the GAL system. We then characterize the memory of the GAL system as the domain of attraction of the steady states. © 2011 Springer Science+Business Media B.V.

关键词： Cellular memory Domain of attraction GAL system ODE model Saccharomyces cerevisiae

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Efficiently generalizing ultra-cold atomic simulations via inhomogeneous dynamical mean-field theory from two-to three-dimensions

Efficiently generalizing ultra-cold atomic simulations via i...

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2010 DoD High Performance Computing Modernization Program Users Group Conference, HPCMP UGC 2010

作者： Freericks, J.K. Krishnamurthy, H.R. Carrier, P. Saad, Y. Department of Physics Georgetown University Washington DC United States Centre for Condensed Matter Theory Department of Physics Indian Institute of Science Bangalore 560012 India Department of Computer Science and Engineering Minnesota Supercomputing Institute University of Minnesota Minneapolis MN United States

ISBN: (纸本)9780769543925

We describe techniques that we are implementing to move inhomogeneous dynamical mean-field theory simulations from two-to three-dimensions. Two-dimensional simulations typically run on 2,000-10,000 lattice sites, while three-dimensional simulations typically need to run on 1,000,000 or more lattice sites. The inhomogeneous dynamical mean-field theory requires the diagonal of the inverse of many sparse matrices with the same sparsity pattern, and a dimension equal to the number of lattice-sites. For two-dimensional systems, we have employed general dense LAPACK routines since the matrices are small enough. For three-dimensional systems, we need to employ sparse matrix techniques. Here, we present one possible strategy for the sparse matrix routine, based on the well-known Lanczos technique, with a long run of the algorithm and (partial) reorthogonalization. This approach is about two-times faster than the LAPACK routines with identical accuracy, and hence will become the standard we use on the two-dimensional problems. We illustrate this approach on the problem of increasing the efficiency for pre-forming dipolar molecules in K-Rb mixtures on a lattice. We compare the local density approximation to inhomogeneous dynamical mean-field theory to illustrate how the local density approximation fails at low-temperature, and to illustrate the benefits of the new algorithms. For a three-dimensional problem, a speed-up of 1,000 or more times is needed. We end by discussing some options that are promising toward reaching this goal. © 2011 IEEE.

关键词： Binary alloys

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Lanczos-based Low-Rank Correction Method for Solving the Dyson Equation in Inhomogenous Dynamical Mean-Field Theory

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Physics Procedia 2011年 15卷 22-28页

作者： Pierre Carrier Jok M. Tang Yousef Saad James K. Freericks Department of Computer Science & Engineering and Minnesota Supercomputing Institute University of Minnesota Minneapolis Minnesota 55455 Department of Physics Georgetown University Washington D.C. 20057

Inhomogeneous dynamical mean-field theory has been employed to solve many interesting strongly interacting problems from transport in multilayered devices to the properties of ultracold atoms in a trap. The main computational step, especially for large systems, is the problem of calculating the inverse of a large sparse matrix to solve Dyson's equation and determine the local Green's function at each lattice site from the corresponding local self-energy. We present a new e_cient algorithm, the Lanczos-based low-rank algorithm, for the calculation of the inverse of a large sparse matrix which yields this local (imaginary time) Green's function. The Lanczos-based low-rank algorithm is based on a domain decomposition viewpoint, but avoids explicit calculation of Schur complements and relies instead on low-rank matrix approximations derived from the Lanczos algorithm, for solving the Dyson equation. We report at least a 25-fold improvement of performance compared to explicit decomposition (such as sparse LU) of the matrix inverse. We also report that scaling relative to matrix sizes, of the low-rank correction method on the one hand and domain decomposition methods on the other, are comparable.

关键词： Lanczos Matrix inversion Inhomogeneous Dynamical Mean-Field Theory Green's functions

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Soft-in soft-out DFE and Bi-directional DFE

Soft-in soft-out DFE and Bi-directional DFE

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作者： Jeong, Seongwook Moon, Jaekyun Dept. of Electrical and Computer Engineering University of Minnesota Minneapolis MN 55455 United States Dept. of Electrical Engineering Korea Advanced Institute of Science and Technology Daejeon 305-701 Korea Republic of

We design a soft-in soft-out (SISO) decision feedback equalizer (DFE) that performs better than its linear counterpart in turbo equalizer (TE) setting. Unlike previously developed SISO-DFEs, the present DFE scheme relies on extrinsic information formulation that directly takes into account the error propagation effect. With this new approach, both error rate simulation and the extrinsic information transfer (EXIT) chart analysis indicate that the proposed SISO-DFE is superior to the well-known SISO linear equalizer (LE). This result is in contrast with the general understanding today that the error propagation effect of the DFE degrades the overall TE performance below that of the TE based on a LE. We also describe a new extrinsic information combining strategy involving the outputs of two DFEs running in opposite directions, that explores error correlation between the two sets of DFE outputs. When this method is combined with the new DFE extrinsic information formulation, the resulting "bidirectional" turbo-DFE achieves excellent performance-complexity tradeoffs compared to the TE based on the BCJR algorithm or on the LE. Unlike turbo LE or turbo DFE, the turbo BiDFE's performance does not degrade significantly as the feedforward and feedback filter taps are constrained to be time-invariant. © 2011 IEEE.

关键词： Iterative methods

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Toward More Secure, Stronger and Smarter Electric Power Grids

Toward More Secure, Stronger and Smarter Electric Power Grid...

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IEEE Power and Energy Society General Meeting

作者： S. Massoud Amin Technological Leadership Institute (TLI) and the Department of Electrical and Computer Engineering University of Minnesota

ISBN: (纸本)9781457710001

Grid communications and control systems are often thought to be much more securely protected than is actually the case. An effective remedial program begins with a thorough and clear-eyed assessment of all vulnerabilities;especially to malware and intrusions. Both the importance and difficulty of protecting power systems have long been recognized. The critical assets that must be accounted for include thousands of transformers, line reactors, series capacitors, and transmission lines. Physical protection of these widely diverse and dispersed assets is impractical and command control layers yield new benefits only if designed correctly and securely, posing additional challenges. Our strategic focus is to better understand the true dynamics of complex interdependent energy/communications/economic networks in order to enable stronger, greener, more secure and smarter power grids. The objective of this project is to model, design and develop a reconfigurable smart end-to-end system supported by secure sensing/wireless communication network and fault-resilient real-time controls.

关键词： Cyber Security Power Systems Smart Grids Network security Smart grids power systems Power grids electric power grids Secure model design intrusions

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Self-Iterating Soft Equalizer

Self-Iterating Soft Equalizer

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2011 IEEE Global Telecommunications Conference - GLOBECOM 2011

作者： Seongwook Jeong Jaekyun Moon Department of Electrical and Computer Engineering University of Minnesota Minneapolis MN USA Department of Electrical Engineering Korea Advanced Institute of Science and Technology Daejeon South Korea

We design a self-iterating soft equalizer (SISE) consisting of several suboptimal equalizers that are weak individually but, when working together, show good performance. In order to process correlated soft information through serially concatenated modules, a sophisticated method to generate the extrinsic information is proposed that suppresses the correlation effect between the soft information of suboptimal equalizers. This algorithm performs well in turbo equalization system as well as the classic uncoded equalization system. The performance advantages are validated with bit-error-rate (BER) simulations and extrinsic information transfer (EXIT) chart analysis.

关键词： Decoding Noise Correlation Decision feedback equalizers Indexes Bit error rate

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A generic framework for scalable and convergent multi-robot active simultaneous localization, mapping and target tracking

A generic framework for scalable and convergent multi-robot ...

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Mediterranean Conference on Control and Automation

作者： Kosmatopoulos, E.B. Rovas, D.V. Doitsidis, L. Aboudolas, K. Roumeliotis, S.I. Dept. of Electrical and Computer Engineering Democritus University of Thrace Xanthi 67100 Greece 6th km Xarilaou Thermi 57001 Thessaloniki Greece Dept. of Production and Management Engineering Technical University of Crete Chania 73100 Greece Dept. of Electronics Technological Educational Institute of Crete Chania 73100 Greece Dept. of Computer Science and Engineering University of Minnesota EE/CS 5-189 200 Union St. SE Minneapolis Minneapolis MN 55455 United States

ISBN: (纸本)9781457701252

In this paper, a new approach is proposed and analyzed for developing efficient and scalable methodologies for multi-robot active Cooperative Simultaneous Localization And Mapping and Target Tracking (C-SLAMTT). The proposed approach employs an active estimation scheme that switches among linear elements and, as a result, its computational requirements scale linearly with the number of estimated quantities (number of number of robots, landmarks and targets). The parameters of the proposed scheme are calculated off-line using a convex optimization algorithm which is based on Semi-Definite Programming (SDP) and approximation using Sum-of-Squares (SoS) polynomials. As shown by rigorous arguments, the estimation accuracy of the proposed scheme is equal to the optimal estimation accuracy plus a term that is inversely proportional to the number of estimator's switching elements (or, equivalently, to the memory storage capacity of the robots' equipment). The proposed approach can handle various types of constraints such as stay-within-an-area, obstacle avoidance and maximum speed constraints. The efficiency of the approach is demonstrated on a 3D active cooperative simultaneous mapping and target tracking application employing flying robots. © 2011 IEEE.

关键词： Mapping

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