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Impact of Non-Poissonian Activity Patterns on Spreading Processes

Physical Review Letters 2007年第15期98卷 158702-158702页

作者： Alexei Vazquez Balázs Rácz András Lukács Albert-László Barabási The Simons Center for Systems Biology Institute of Advanced Study Einstein Drive Princeton New Jersey 08540 USA Computer and Automation Research Institute Hungarian Academy of Sciences (MTA SZTAKI) Budapest Hungary Department of Physics and Center for Complex Networks Research University of Notre Dame Notre Dame Indiana 46556 USA

Halting a computer or biological virus outbreak requires a detailed understanding of the timing of the interactions between susceptible and infected individuals. While current spreading models assume that users interact uniformly in time, following a Poisson process, a series of recent measurements indicates that the intercontact time distribution is heavy tailed, corresponding to a temporally inhomogeneous bursty contact process. Here we show that the non-Poisson nature of the contact dynamics results in prevalence decay times significantly larger than predicted by the standard Poisson process based models. Our predictions are in agreement with the detailed time resolved prevalence data of computer viruses, which, according to virus bulletins, show a decay time close to a year, in contrast with the 1 day decay predicted by the standard Poisson process based models.

关键词： .Poisson process prevalence spreading activity patterns PRL week time distribution viruses decay times

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A new approach in urban traffic control systems

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Periodica Polytechnica Transportation Engineering 2007年第1-2期35卷 3-13页

作者： Varga, István Bokor, József Systems and Control Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences Kende u. 13-17 H-1111 Budapest Hungary Department of Control and Transport Automation Budapest University of Technology and Economics Bertalan L. u. 2 H-1111 Budapest Hungary

The paper proposes some new methods for traffic control systems design. The goal was to find solutions that make possible to give constraints in course of the estimation process of the road traffic parameters and the traffic controller system design. The proposed solutions are built on the constrained Moving Horizon Estimation and the Fault Detection Filter technique.

关键词： Traffic control

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Design of H_(infinity) Command and Control Loops for Unmanned Aerial Vehicles using Static Output-Feedback

Design of H_(infinity) Command and Control Loops for Unmanne...

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Proceedings of the 46th IEEE Conference on Decision and Control, Pages 1-459

作者： J. Gadewadikar F. Lewis K. Subbarao Ben M. Chen Systems Research Institute Department of Advanced Technologies Alcorn State University USA Automation and Robotics Research Institute University of Texas Arlington Fort worth TX USA Mechanical and Aerospace Department University of Texas Arlington TX USA Department of Electrical & Computer Engineering National University of Singapore Singapore

The aim of this paper is to design a helicopter position control system with guaranteed performance that allows tracking control of Unmanned Aerial Vehicle positions -^sX, Y, Z, and yaw while preserving a structure that is generally accepted in the helicopter control community. The paper presents an approach for designing compensators for shaping the closed-loop inertial positions and yaw step response using H_(infinity) output-feedback design techniques. Simplified conditions are used which only require the solution of two coupled matrix design equations. H_(infinity) framework is utilized to pose the problem of stabilization as an outer position command loop and an inner control loop. Inner loop controls attitude rates along with roll and pitch and provides robustness and structure. This paper thereby presents a design for hover and station-keeping control of UAV helicopters. It is shown that the rotorcraft model can be first loop shaped to achieve desired characteristics about the hover operating condition. A numerically efficient solution algorithm to solve the H_(infinity) coupled design equations for both inner and outer loops is used. A major contribution is that an initial stabilizing gain is not needed. The efficacy of the control law and the disturbance accommodation properties are shown on a rotorcraft design example.

关键词： Helicopters Unmanned aerial vehicles Control systems Attitude control Riccati equations Vehicle dynamics Output feedback Linear matrix inequalities Shape control USA Councils

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Federated filtering for fault tolerant estimation and sensor redundancy management in coupled dynamics distributed systems

Federated filtering for fault tolerant estimation and sensor...

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Mediterranean Conference on Control and automation (MED)

作者： A. Edelmayer M. Miranda Faculty of Engineering Department of Chemical Engineering Laboratory of Unit Operations University de Los Andes Merida Venezuela Systems and Control Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences Budapest Hungary

This paper discusses the application of the idea of federated filtering to the estimation of intrinsically nonlinear distributed systems by examining its impacts on filtering performance by using the Extended Kalman Filter (EKF) as state estimator. Specifically, the performance of the traditional centralized solution is compared with the filtering structure obtained using the federating idea, and their conceptions, and their ability to balance between fault tolerance and estimation accuracy is examined. Our research demonstrates how successfully the EKF for solving nonlinear estimation problems in federated structures can be used, noting that the idea of federation have only been demonstrated for linear problems previously. In addressing the demands of both fault tolerance and estimation accuracy, it is shown that increased filtering accuracy is relied on the proper choice of sharing of the error covariance information between local filters, while sensor fault tolerance is provided by the utilization of an appropriate resetting policy of the filter.

关键词： Fault tolerant systems Sensor systems Redundancy Nonlinear filters Fault tolerance Control systems Information filtering Information filters computer architecture Sensor arrays

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A Study On Iterative Learning Control With Adjustment Of Learning Interval For Monotone Convergence In The Sense Of Sup-Norm

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Asian Journal of Control 2008年第1期4卷

作者： Kwang-Hyun Park Zeungnam Bien Division of EE Department of EECS Korea Advanced Institute of Science and Technology 373–1 Kusong-dong Yusong-gu Taejon 305–701 Korea. Zeungname Bien:received the B.S. degree in electronics engineering from Seoul National University Seoul Korea in 1969 and the M.S. and Ph.D. degrees in electrical engineering from the University of Iowa Iowa City Iowa U.S.A. in 1972 and 1975 respectively. During 1976–1977 academic years he taught as assistant professor at the Department of Electrical Engineering University of Iowa. Then Dr. Bien joined Korea Advanced Institute of Science and Technology summer 1977 and is now Professor of Control Engineering at the Department of Electrical Engineering and Computer Science KAIST. Dr. Bien was the president of the Korea Fuzzy Logic and Intelligent Systems Society during 1990–1995 and also the general chair of IFSA World Congress 1993 and for FUZZ-IEEE99 respectively. He is currently co-Editor-in-Chief for International Journal of Fuzzy Systems (IJFS) Associate Editor for IEEE Transactions on Fuzzy Systems and a regional editor for the International Journal of Intelligent Automation and Soft Computing. He has been serving as Vice President for IFSA since 1997 and is now Chief Chairman of Institute of Electronics Engineers of Korea and Director of Humanfriendly Welfare Robot System Research Center. His current research interests include intelligent control methods with emphasis on fuzzy logic systems service robotics and rehabilitation engineering and large-scale industrial control systems. Kwang-Hyun Park:received the B.S. M.S. and Ph.D. degrees in electrical engineering and computer science from KAIST Korea in 1994 19997 and 2001 respectively. He is now a researcher at Human-friendly Welfare Robot System Research Center. His research interests include learning control machine learning human-friendly interfaces and service robotics.

It has been found that some huge overshoot in the sense of sup-norm may be observed when typical iterative learning control (ILC) algorithms are applied to LTI systems, even though monotone convergence in the sense of λ-norm is guaranteed. In this paper, a new ILC algorithm with adjustment of learning interval is proposed to resolve such an undesirable phenomenon, and it is shown that the output error can be monotonically converged to zero in the sense of sup-norm when the proposed ILC algorithm is applied. A numerical example is given to show the effectiveness of the proposed algorithm.

关键词： Iterative learning control monotone convergence learning interval sup-norm

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Polytopic Decomposition of the Linear Parameter-varying Model of the Parallel-type Double inverted Pendulum

Polytopic Decomposition of the Linear Parameter-varying Mode...

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IEEE International Conference on Intelligent Engineering systems (INES)

作者： Szabolcs Nagy Zoltan Petres Peter Baranyi Laszlo Szeidl Pal Michelberger Systems and Control Lab Computer and Automation Research Institute Hungarian Academy of Sciences (ATOMKI) Budapest Hungary Budapest Tech Polytechnical Institution Budapest Hungary Department of Vehicle and Light Weight Structures Analysis Budapest University슠of슠Technology슠and슠Economics Hungary

Most of the formal controller synthesis approaches require conditions like controllability, observability of the systems, however it is still difficult to verify these properties in general. In case of polytopic models these conditions and the feasibility of the linear matrix inequalities (LMI) based design strongly depends on the weighting of the LTI vertex components of the polytopic model. With tensor product (TP) model transformation it is possible to decompose linear parameter-varying (LPV) models into polytopic forms in various ways and also provides the appropriate weighting functions. The objective of this paper is to use this decomposition on the the parallel-type double inverted pendulum control problem.

关键词： Tensile stress Strontium Automatic control Control system synthesis Lighting control Linear matrix inequalities Matrix decomposition Concurrent computing automation Electronic mail

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TRACKING CONTROL IN THE PRESENCE OF NONLINEAR DYNAMIC FRICTIONAL EFFECTS: ROBOT EXTENSION

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Asian Journal of Control 2008年第3期1卷

作者： M. Feemster D.M. Dawson A. Behal W. Dixon Matthew Feemster received the B.S degree in Electrical Engineering from Clemson University Clemson South Carolina in December 1994. Upon graduation he remained at Clemson University and received the M.S. degree in Electrical Engineering in 1997. During this time he also served as a research/teaching assistant. His research work focused on the design and implementation of various nonlinear control algorithms with emphasis on the induction motor and mechanical systems with friction present. He is currently working toward his Ph.D. degree in Electrical Engineering at Clemson University. Darren M. Dawson was born in 1962 in Macon Georgia. He received an Associate Degree in Mathematics from Macon Junior College in 1982 and a B.S. Degree in Electrical Engineering from the Georgia Institute of Technology in 1984. He then worked for Westinghouse as a control engineer from 1985 to 1987. In 1987 he returned to the Georgia Institute of Technology where he received the Ph.D. Degree in Electrical Engineering in March 1990. During this time he also served as a research/teaching assistant. In July 1990 he joined the Electrical and Computer Engineering Department and the Center for Advanced Manufacturing (CAM) at Clemson University where he currently holds the position of Professor. Under the CAM director's supervision he currently leads the Robotics and Manufacturing Automation Laboratory which is jointly operated by the Electrical and Mechanical Engineering departments. His main research interests are in the fields of nonlinear based robust adaptive and learning control with application to electro-mechanical systems including robot manipulators motor drives magnetic bearings flexible cables flexible beams and high-speed transport systems. Aman Behal was born in India in 1973. He received his Masters Degree in Electrical Engineering from Indian Institute of Technology Bombay in 1996. He is currently working towards a Ph.D in Controls and Robotics at Clemson University. His research focuses on the control of no

In this paper, we extend the observer/control strategies previously published in [25] to an n -link, serially connected, direct drive, rigid link, revolute robot operating in the presence of nonlinear friction effects modeled by the Lu-Gre model. In addition, we also present a new adaptive control technique for compensating for the nonlinear parameterizable Stribeck effects. Specifically, an adaptive observer/controller scheme is developed which contains a feedforward approximation of the Stribeck effects. This feedforward approximation is used in a composite controller/observer strategy which forces the average square integral of the position tracking error to an arbitrarily small value. Experimental results are included to illustrate the performance of the proposed controllers.

关键词： Friction compensation nonlinear control

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Two-phase semantic web service discovery method for finding intersection matches using logic programming

Two-phase semantic web service discovery method for finding ...

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Workshop on Semantics for Web Services, SemWS 2006

作者： Kovács, László Micsik, András Pallinger, Péter MTA SZTAKI Computer and Automation Research Institute of the Hungarian Academy of Sciences Department of Distributed Systems Germany

Discovering Web Services based on logical matching of capabilities is a new requirement for Semantic Web Services which cannot be solved with traditional information retrieval (IR) techniques. Building fast and precise logical discovery engines is an ongoing challenge of the Semantic Web community. This paper presents the discovery engine implemented for the INFRAWEBS project which combines a traditional IR-based pre-filtering step and a logicbased matching implemented in Prolog. The logicbased step of discovery uses a novel technique based on Prolog-style unification of terms. This approach performs well in finding matches of intersection type, and it also provides possibilities to compare, rank and explain these matches. © The Electrochemical Society.

关键词： Engines

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Tillarom: An AJAX based folk song search and retrieval system with gesture interface based on kodály hand

Tillarom: An AJAX based folk song search and retrieval syste...

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1st ACM International Workshop on Human-Centered Multimedia, HCM 2006, co-located with the 2006 ACM International Multimedia Conference

作者： Licsár, Attila Szirányi, Tamás Kovács, László Pataki, Balázs University of Pannonia Department of Image Processing and Neurocomputing Egyetem u. 10 H-8200 Veszprém Hungary Department of Distributed Systems Computer and Automation Research Institute Hungarian Academy of Sciences Lágymányosi u. 11 H-1111 Budapest Hungary Analogical and Neural Computing Laboratory Computer and Automation Research Institute Hungarian Academy of Sciences Lágymányosi u. 11 H-1111 Budapest Hungary

ISBN: (纸本)1595935002

A digital folk song search and retrieval system with a hand gesture based interface is presented. Tillarom is a comprehensive collection of original Hungarian folk songs recorded using different technologies such as phonographs and/or stereo DAT cassettes. This digital archive contains professional quality metadata records as well as MIDI recordings for presenting the different types of clustered folk songs. An AJAX based search and retrieval interface was developed that can be used together with optically recognized Kodály's hand signs to formulate queries through a web browser. The appearance based recognition of hand gestures utilizes contour analysis and SVM based classification. We evaluated the performance of the recognition of hand signs and investigated the main problems of their usage in our system. Copyright 2006 ACM.

关键词： Information systems

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Eliminating execution overhead of disabled optional features in connectors 1

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3rd European Workshop on Software Architecture, EWSA 2006

作者： Bulej, LubomÍr Bure Š, TomÁš Distributed Systems Research Group Department of Software Engineering Charles University Malostranské nám. 25 Prague118 00 Czech Republic Institute of Computer Science Academy of Sciences of the Czech Republic Pod Vodárenskou věží 2 Prague182 07 Czech Republic

ISBN: (数字)9783540692720

ISBN: (纸本)9783540692713

Connectors are used to realize component interactions in component systems. Apart from their primary function, which is mediating the communication, their implementation can also support additional features that, while unrelated to the primary function, may benefit from their placement in connectors. Such features are often optional in the sense that they can be activated and deactivated at run-time. The problem is that even if they are disabled, their very presence in the connector incurs certain overhead. In this paper, we describe an approach to eliminate this overhead by reconfiguration of the connector implementation. Besides connectors, the approach is applicable to similar technologies such as reflective middleware and other architecture-based component systems and frameworks. © Springer-Verlag Berlin Heidelberg 2006.

关键词： Middleware

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