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Network reconfiguration of distributed controlled homogenous power inverter network using composite Lyapunov function based reachability bound

Network reconfiguration of distributed controlled homogenous...

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Summer computer Simulation Conference 2007, SCSC 2007, Part of the 2007 Summer Simulation Multiconference, SummerSim 2007

作者： Mazumder, Sudip K. Acharya, Kaustuva Tahir, Muhammad Laboratory of Energy and Switching-electronics Systems Department of Electrical and Computer Engineering University of Illinois Chicago United States

ISBN: (纸本)9781622763580

We outline a methodology to determine the reachability bound of a homogeneous interactive power network (IPN) with wireless distributed control by using a piecewise linear (PWL) model of the system. By formulating a convex optimization problem based on a composite Lyapunov function and solving this problem using linear-matrix-inequality solvers, we predict the reaching criteria for orbital existence. We investigate the impacts of time delays due to the wireless network and communication-channel disruptions on the reachability bound and performance of the IPN. Because of the infeasibility of modeling such network control systems (NCS) in a deterministic framework, we adopt a probabilistic approach based on Markov chains to model the wireless network and incorporate them into the PWL models of the system. Using these models, we analyze the reaching conditions of the IPN in a probabilistic domain and comment on the mean-square stability of the system. Further, we demonstrate how communication fault-tolerant protocols can be implemented to ensure that the IPNs operate within their reachability and performance bounds, despite one or more disruptions in the communication channels.

关键词： Wireless networks

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Message passing and distributed statistical inference 45

Message passing and distributed statistical inference

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45th Annual Allerton Conference on Communication, Control, and Computing 2007

作者： Chandrasekaran, Venkat Johnson, Jason Kreidl, O. Patrick Malioutov, Dmitry Sanghavi, Sujay Willsky, Alan S. Department of Electrical Engineering and Computer Science Laboratory for Information and Decision Systems MIT CambridgeMA United States

ISBN: (纸本)9781605600864

In this paper , we summarize several research directions involving message-passing algorithms and distributed fusion. The starting point is inference for graphical models , but the different constraints and objectives found in sensor networks suggest new questions. In addition to providing pointers to a variety of other parts of our research in this area , we spend most of our time on two research investigations. The irst involves team-theoretic approaches to distributed decision-making and the development of message-passing algorithms for sensor network organization in order to optimize distributed team objectives. The second deals with the exploitation of so-called walk-sum analysis for distributed linear estimation. In particular under an easily checked condition for walk-summability , we can show that essentially any messaging strategy converges to the optimal distributed solution;moreover with modest use of local memory , this remains true in the presence of random message losses. We also describe how this framework leads to a tractable max-spanning tree problem for optimal adaptive message routing-i.e. , for determining a spanning tree for the next wave of messages to reduce an upper bound on estimation error as quickly as possible.

关键词： Sensor networks

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A combined integral transform asymptotic expansion method for the characterization of interface flaws through pulsed infrared thermography1

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Quantitative InfraRed Thermography Journal 2007年第1期4卷 3-23页

作者： Bendada, Abdelhakim Ibarra-Castanedo, Clemente Maldague, Xavier Computer Vision and Systems Laboratory Department of Electrical and Computer Engineering Université Laval Quebec City G1K7P4 Canada

This work is devoted to the non-destructive evaluation of materials using stimulated infrared thermography. The proposed approach provides simple analytical solutions to evaluate the lateral extent, and the thickness of a plane flaw in a three-dimensional (3D) heat transfer configuration. It is based on the application of a Laplace transform on the time variable t, then a double Fourier transform on the space variables x and y. Reduction of the models is obtained through an asymptotic expansion method. This mathematical formalism leads to the construction of explicit relationships that are very convenient for quantitative inversion. An experimental validation of the inversion procedures is performed on calibrated carbon-epoxy laminates. A particular attention is dedicated in the second part of this work to the experimental analysis of the impact of the definition of the experimental thermal contrast and the sane (i.e., non-defective) area on the inverted parameters. The analysis is carried out through a comparison between two classical definitions of the thermal contrast and a new method, the DAC contrast, developed recently by our team. The impact of a hyper parameter of the inversion procedures (i.e., the Laplace variable) is also analyzed. Both analyses are illustrated through an experiment aiming to estimate the depths of some calibrated flaws in a CFRP laminate. © 2007 Taylor & Francis Group, LLC. All rights reserved.

关键词： 3D heat transfer DAC thermal contrast Flaw characterization Infrared thermography Mathematical perturbations Non destructive evaluation Thermal quadrupoles

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Performance of a self-paced brain computer interface on data contaminated with eye-movement artifacts and on data recorded in a subsequent session

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Computational Intelligence and Neuroscience 2008年第1期2008卷 749204页

作者： Fatourechi, Mehrdad Ward, Rabab K. Birch, Gary E. Image and Signal Processing Laboratory Department of Electrical and Computer Engineering University of British Columbia Vancouver BC V6T 1Z4 Canada Institute for Computing Information and Cognitive Systems University of British Columbia Vancouver BC V6T 1Z4 Canada Neil Squire Society Burnaby BC V5M 3Z3 Canada

The performance of a specific self-paced BCI (SBCI) is investigated using two different datasets to determine its suitability for using online: (1) data contaminated with large-amplitude eye movements, and (2) data recorded in a session subsequent to the original sessions used to design the system. No part of the data was rejected in the subsequent session. Therefore, this dataset can be regarded as a pseudo-online test set. The SBCI under investigation uses features extracted from three specific neurological phenomena. Each of these neurological phenomena belongs to a different frequency band. Since many prominent artifacts are either of mostly low-frequency (e.g., eye movements) or mostly high-frequency nature (e.g., muscle movements), it is expected that the system shows a fairly robust performance over artifact-contaminated data. Analysis of the data of four participants using epochs contaminated with large-amplitude eye-movement artifacts shows that the system's performance deteriorates only slightly. Furthermore, the system's performance during the session subsequent to the original sessions remained largely the same as in the original sessions for three out of the four participants. This moderate drop in performance can be considered tolerable, since allowing artifact-contaminated data to be used as inputs makes the system available for users at ALL times.

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Introduction to the special issue on models, theory, and codes for relaying and cooperation in communication networks

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IEEE TRANSACTIONS ON INFORMATION THEORY 2007年第10期53卷 3297-3301页

作者： Kramer, Gerhard Berry, Randall El Gamal, Abbas El Gamal, Hesham Franceschetti, MAssimo Gastpar, Michael Laneman, J. Nicholas Bell Labs Alcatel-Lucent Murray Hill NJ United States Department of Electrical Engineering and Computer Science Northwestern University Evanston IL United States Department of Electrical Engineering Information Systems Laboratory Stanford University Stanford CA United States Electrical Engineering Department Ohio State University (OSU) Columbus OH United States Department of Electrical and Computer Engineering University of California San Diego (UCSD) La Jolla CA United States University of California Berkeley CA United States Faculty of the Department of Electrical Engineering University of Notre Dame Notre Dame IN United States

The thirty-four papers in this special issue are devoted to models, theories, and codes for relaying and cooperation in communication networks. The demand for large, more efficient, reliable, and cost effective communication networks is motivating new network architectures for cellular and wireless communications as well as cognitive radio and sensor networks.

关键词： Special issues and sections Relays Communication networks Telecommunication network reliability Costs Communication effectiveness Cellular networks Wireless communication Cognitive radio Wireless sensor networks

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Delay defect diagnosis using segment network faults

Delay defect diagnosis using segment network faults

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2007 IEEE International Test Conference, ITC

作者： Poku, Osei Blanton, R.D. Laboratory for Integrated Systems Test Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA 15213 United States

ISBN: (纸本)1424411289

An objective of delay fault diagnosis is to enable characterization of the source and nature of timing failure in an integrated circuit. However, the most commonly studied defect models (the gate-delay and path-delay fault models) do not adequately capture the complex timing characteristics that a delay fault can exhibit. In this work, we present a novel diagnostic technique that is used to extract an accurate delay fault model we call a segment network fault without the need for any timing information. In our simulation-based experiments, we successfully diagnose delay faults of varying complexity demonstrating the usefulness of the new delay fault model for the purposes of delay defect characterization. © 2007 IEEE.

关键词： Integrated circuit layout

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Spatial Diversity in Signal Strength based WLAN Location Determination systems

Spatial Diversity in Signal Strength based WLAN Location Det...

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Conference on Local computer Networks (LCN)

作者： Anil Ramachandran S. Jagannathan Embedded Systems and Networking Laboratory Department of Electrical and Computer Engineering University of Missouri Rolla USA

Literature indicates that spatial diversity can be utilized to compensate channel uncertainties such as multipath fading. Therefore, in this paper, spatial diversity is exploited for locating stationary and mobile objects in the indoor environment. First, space diversity technique is introduced for small scale motion and temporal variation compensation of received signal strength and it is demonstrated analytically that it enhances location accuracy. Small scale motion refers to movements of the transmitter and/or the receiver of the order of sub-wavelengths while temporal effects refer to environmental variations with time. A novel metric is introduced for selection combining in order to improve location accuracy through the addition of spatial diversity upon two available location determination schemes. The results are evaluated experimentally against single antenna system for reception by using low cost wireless RF devices such as motes. Alternatively, the impact of the number of location determination devices in a probabilistic WLAN network based on pre-profiling of signal strength is analyzed and it is demonstrated analytically that location accuracy improves with the number of receivers used. Spatial diversity in terms of the antenna spacing of 2lambda is evaluated and shown to provide a reduction in location determination error between 30 and 40% when compared to a single antenna system.

关键词： Wireless LAN Diversity reception Signal analysis Uncertainty Fading Indoor environments Motion analysis Transmitters Costs Radio frequency

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Formal embedding of the Spring Loaded Inverted Pendulum in an Asymmetric hopper 9

Formal embedding of the Spring Loaded Inverted Pendulum in a...

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2007 9th European Control Conference, ECC 2007

作者： Poulakakis, Ioannis Grizzle, J.W. Control Systems Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48105 United States

ISBN: (纸本)9783952417386

The control of running is discussed in terms of a model called the Asymmetric Spring Loaded Inverted Pendulum (ASLIP), shown in Fig. 1. The ASLIP consists of a Spring Loaded Inverted Pendulum (SLIP) with the addition of pitch dynamics, and can be used to study the sagittal plane motion of bipedal running. A hybrid controller for the ASLIP is developed that acts on two levels. In the first level, continuous in-stride control is used to stabilize the torso at a desired posture, and to create an invariant surface on which the stance dynamics of the closed-loop system is diffeomorphic to the center of mass dynamics of a SLIP. In the second level, event-based control is employed to stabilize the closed-loop hybrid system along a periodic orbit of the SLIP dynamics. These results provide a systematic framework for designing control laws with provable stability properties which take advantage of existing SLIP controllers that are known to induce elegant running motions in legged models. © 2007 EUCA.

关键词： Closed loop systems

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Use of Frequency Diversity in Signal Strength based WLAN Location Determination systems

Use of Frequency Diversity in Signal Strength based WLAN Loc...

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Conference on Local computer Networks (LCN)

作者： Anil Ramachandran Jagannathan Sarangapani Embedded Systems and Networking Laboratory Department of Electrical and Computer Engineering University of Missouri Rolla Rolla MO USA

Literature indicates that frequency diversity can be utilized to compensate channel uncertainties such as multipath fading. Therefore, in this paper it is exploited for improving accuracy in locating stationary and mobile objects in the indoor environment. First, frequency diversity technique is introduced for small scale and temporal variation compensation of received signals and demonstrated analytically that it in fact enhances location accuracy. A novel metric is introduced in selection combining in order to achieve location accuracy through the addition of frequency diversity upon two of the available location determination schemes. The results are evaluated experimentally against the case where there is no frequency diversity for reception by using low cost wireless RF devices such as motes. An asset location tracking system is then devised to both improve accuracy and predict asset movement. Frequency diversity in terms of channel spacing of 55 MHz is evaluated and shown to provide a reduction in location determination error between 18 and 23% when compared to a system without frequency diversity. Finally, results from frequency diversity are compared against the spatial diversity techniques in terms of improvement in location accuracy, power consumption of the transmitter, and hardware and software costs.

关键词： Frequency diversity Wireless LAN Diversity reception Costs Uncertainty Fading Indoor environments Signal analysis Radio frequency Tracking

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Probabilistic estimation of state-dependent hybrid mode transitions for aircraft arrival time prediction

Probabilistic estimation of state-dependent hybrid mode tran...

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AIAA Guidance, Navigation, and Control Conference 2007

作者： Huango, Haomiao Roy, Kaushik Tomlin, Claire J. Department of Aeronautics and Astronautics Stanford University AIAA Department of Aeronautics and Astronautics Hybrid Systems Laboratory Stanford University Department of Electrical Engineering and Computer Sciences University of California Berkeley

ISBN: (纸本)1563479044

The problem of accounting for the effects of air-traffic control (ATC) decision-making in modeling arrival traffic flow at airports is approached from a probabilistic perspective. Aircraft routing decisions are incorporated into previous work in developing a Discrete-Time Stochastic Hybrid Linear System for modeling aircraft dynamics and making Estimated Time of Arrival (ETA) predictions. The determination of aircraft path is modeled as a state-dependent discrete mode transition for the hybrid model. We determine the transition probabilities based on the separation (as a result of path choice) between each arriving aircraft and the aircraft immediately in front and show that separation distance is a good predictor for aircraft path choice. We then use the path probabilities to generate probability distributions over possible ETAs. Current methods used by airlines for predicting ETA are deterministic and not robust to ATC decisions on aircraft routing: not knowing exactly which path arriving aircraft are routed through means predictions must be made using only an average, nominal path, from which the aircraft may deviate substantially. NASA's Center/TRACON Automation System makes accurate predictions but uses knowledge of routing decisions. By predicting ATC decisions, we greatly improve ETA predictions without using ATC information. Accounting for re-routing reduces average error in aircraft path prediction from 6nm to 3.5 nm at 10 minutes from landing, with a reduction in ETA error from 2 minutes to 1 minute.

关键词： Aircraft

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