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Scalable Network Parameter Estimation in the Presence of Anomalies

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Scalable Network Parameter Estimation in the Presence of Ano...

IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Saurabh Sihag Ali Tajer Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute

ISBN: (纸本)9781538646595

This paper considers the problem of parameter estimation in a network in which the stochastic model of its measurements can change due to disruption in an unknown subset of sensors. This uncertainty in the measurements model introduces a new dimension to the estimator design. On one hand, the estimation quality depends on the successful isolation of anomalous sensors, and on the other hand, the detection performance is imperfect because of noisy measurements. Motivated by these two observations, this paper models the problem as a composite hypothesis testing problem and analyzes an optimal estimation framework. In large networks, the dimension of the hypotheses testing problem increases exponentially with the size of the network, and also finding the optimal estimate becomes computationally prohibitive. To counter this, this paper provides a scalable solution that consists of detecting and isolating anomalous sensors followed by a sensor-level estimation routine, and establishes asymptotic optimality of the scalable approach. This paper also formulates the decision rules to establish the reliability of the local estimates formed by each sensor, and the local estimates deemed to be reliable are aggregated to form a global estimate. The optimal and scalable schemes are evaluated and compared in a case study.

关键词： Anomaly detection parameter estimation detection and isolation scalable

Distributed Estimation Under Network Model Uncertainty

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Distributed Estimation Under Network Model Uncertainty

IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Saurabh Sihag Ali Tajer Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute

ISBN: (纸本)9781538646595

This paper considers the problem of distributed state estimation in an interconnected network, in which there is uncertainty in the true model. Such uncertainties are due to the possibility of disruptions or changes in the nominal model. The focus is on the setting in which the true network model belongs to a set of possible models. Forming an optimal estimate has high computational complexity in large networks and, therefore, this paper treats this problem in a distributed framework. The key observation is that the estimation quality critically depends on successful isolation of the true model. On the other hand, the true model cannot be determined perfectly due to noisy measurements. Based on these observations, this paper formulates a composite hypotheses testing problem and provides optimal decision rules that account for estimation quality and detection performance. The theory developed in this paper is evaluated via a case study.

关键词： State estimation distributed estimation model uncertainty networks State estimation model uncertainty network model Network Online resources solidification Distribute paper Uncertainty complexity classes

Quickest search for a change point

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arXiv 2018年

作者： Heydari, Javad Tajer, Ali Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute

This paper considers a sequence of random variables generated according to a common distribution. The distribution might undergo periods of transient changes at an unknown set of time instants, referred to as change-points. The objective is to sequentially collect measurements from the sequence and design a dynamic decision rule for the quickest identification of one change-point in real time, while, in parallel, the rate of false alarms is controlled. This setting is different from the conventional change-point detection settings in which there exists at most one change-point that can be either persistent or transient. The problem is considered under the minimax setting with a constraint on the false alarm rate before the first change occurs. It is proved that the Shewhart test achieves exact optimality under worst-case change points and also worst-case data realization. Numerical evaluations are also provided to assess the performance of the decision rule characterized. Copyright © 2018, The Authors. All rights reserved.

关键词： Errors

Outer-linearization-based optimization algorithm for decentralized control design in flexure-linked H-gantry

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Outer-linearization-based optimization algorithm for decentr...

2018 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM 2018

作者： Ma, Jun Chen, Si-Lu Liang, Wenyu Li, Xiaocong Teo, Chek Sing Tay, Arthur Mamun, Abdullah Al Tan, Kok Kiong SIMTech-NUS Joint Lab. on Precision Motion Systems Department of Electrical and Computer Engineering National University of Singapore Singapore117582 Singapore Department of Electrical and Computer Engineering National Universit of Singapore Singapore117583 Singapore Mechatronics Group Singapore Institute of Manufacturing Technology Singapore138634 Singapore Zhejiang Provincial Key Laboratory of Robotics and Intelligent Manufacturing Equipment Technology Ningbo Institute of Industrial Technology Chinese Academy of Sciences Ningbo Zhejiang315121 China

ISBN: (纸本)9781538618547

The dual-drive H-gantry (DHG) is widely used for high-speed high-precision Cartesian motion control applications. Compared with the rigid-linked gantry design, the flexure-linked design is able to prevent the damage of the cross-arm because a small degree of rotation angle is allowed. Nevertheless, the flexure-linked design possibly induces the resonance of the gantry because of the chattering of control signals. To maintain the precision tracking of two carriages and minimize the chattering of control efforts, we aim to seek the most suitable flexure joints among the available ones and optimize the decentralized feedback controller parameters under parametric uncertainties. The mechatronic design problem is formulated as an H2 guaranteed cost control problem. All the stabilizing feedback controller gains are parameterized over a convex set, from here, numerical procedures are developed to obtain the global optimum by means of an outer-linearization-based optimization algorithm. Experiments are carried out and the results successfully validate the optimality and the robustness of the proposed design approach. © 2018 IEEE.

关键词： Feedback control

Vehicular Multi-Camera Sensor System for Automated Visual Inspection of Electric Power Distribution Equipment

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Vehicular Multi-Camera Sensor System for Automated Visual In...

2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Jinsun Park Ukcheol Shin Gyumin Shim Kyungdon Joo Francois Rameau Junhyeok Kim Dong-Geol Choi In So Kweon Robotics and Computer Vision Laboratory School of Electrical Engineering KAIST Daejeon Republic of Korea Korea Electric Power Corporation Korea Electric Power Research Institute Daejeon Republic of Korea Department of Information and Communication Engineering Hanbat National University Daejeon Republic of Korea

In this paper, we present a multi-camera sensor system along with its control algorithm for automated visual inspection from a moving vehicle. To accomplish this task, we propose a unique hardware configuration consisting of a frontal stereo vision system, six lateral cameras motorized to tilt, and a GPS/IMU sensor mounted on the roof of a car. From the frontal stereo system, we detect electric poles and estimate their corresponding 3D positions. Based on this 3D estimation, the tilt angles of the motorized lateral cameras are controlled in real-time to capture high resolution images of the equipment - typically installed a few meters above the road surface. In addition, inertial odometry information from the GPS/IMU module is utilized for pose estimation, object localization, and re-identification among cameras. Experimental results demonstrate the efficiency and robustness of our system for automated electric equipment maintenance, which can reduce human effort significantly.

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Sequence Impedance Modeling and Converter-Grid Resonance Analysis Considering DC Bus Dynamics and Mirrored Harmonics

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Sequence Impedance Modeling and Converter-Grid Resonance Ana...

IEEE Workshop on Control and Modeling for Power Electronics

作者： Ignacio Vieto Jian Sun Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute

ISBN: (纸本)9781538655429

Sequence impedance models have been developed for two-level voltage source converters by assuming constant dc bus voltage and ignoring coupling over frequency effects. There have been efforts to overcome these limitations but the resulting models are very complex and the formulated system models require generalized Nyquist criterion for stability analysis. This paper presents a new modeling and system analysis method that solves these problems. The method starts by modeling the converter current response at different frequencies to a perturbation in the ac terminal voltage while keeping the dc bus voltage constant, and to a perturbation in the dc terminal voltage while keeping the ac terminal voltage constant. The individual transfer functions are then connected to build the overall converter models that include both the effects of dc bus dynamics and coupling over frequency. For converter-grid system stability analysis, the effects of coupling over frequency are shown to be equivalent to an additional impedance in parallel with the sequence impedance. The developed models are validated individually as well as in system resonance analysis.

关键词： Small-signal sequence impedance Converter modeling System resonance

Payoff Dynamics Model and Evolutionary Dynamics Model: Feedback and Convergence to Equilibria

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arXiv 2019年

作者： Park, Shinkyu Martins, Nuno C. Shamma, Jeff S. Department of Mechanical and Aerospace Engineering Princeton University PrincetonNJ08544 United States Department of Electrical and Computer Engineering and the Institute for Systems Research University of Maryland College ParkMD20742 United States Thuwal23955-6900 Saudi Arabia

We consider that at every instant each member of a population, which we refer to as an agent, selects one strategy out of a finite set. The agents are nondescript, and their strategy choices are described by the so-called population state vector, whose entries are the portions of the population selecting each strategy. Likewise, each entry of the so-called payoff vector is the reward attributed to a strategy. We consider that a finite-dimensional nonlinear dynamical system, denoted as payoff dynamics model (PDM), specifies a mechanism that determines the payoff as a causal map of the population state. A boundedrationality protocol, which is often inspired on evolutionary biology principles, governs how each agent continually revises its strategy based on complete or partial knowledge of the population state and payoff. The population is protocol-homogeneous but is otherwise strategy-heterogeneous considering that the agents are allowed to select distinct strategies concurrently. A stochastic mechanism determines the instants when agents revise their strategies, but we consider that the population is large enough that, with high probability, the population state can be approximated with arbitrary accuracy uniformly over any finite horizon by a so-called (deterministic) mean population state. We propose an approach that takes advantage of passivity principles to obtain sufficient conditions determining, for a given protocol and PDM, when the mean population state is guaranteed to converge to a meaningful set of equilibria, which could be either an appropriately defined extension of Nash-s for the PDM or a perturbed version of it. By generalizing and unifying previous work, our framework also provides a foundation for future work. We specialize our results for well-known protocols and a class of PDM that includes as particular cases the payoff mechanisms proposed in previous work to model learning, inertia, and anticipation. Copyright © 2019, The Authors. All rights re

关键词： Stochastic systems

Simultaneous state and parameter estimation: The role of sensitivity analysis

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arXiv 2020年

作者： Liu, Jianbang Gnanasekar, Aristarchus Zhang, Yi Bo, Song Liu, Jinfeng Hu, Jingtao Zou, Tao Key Laboratory of Networked Control Systems Shenyang Institute of Automation Chinese Academy of Sciences Shenyang110016 China Institute for Robotics & Intelligent Manufacturing Chinese Academy of Sciences Shenyang110016 China University of Chinese Academy of Sciences Beijing100049 China Department of Chemical & Materials Engineering University of Alberta EdmontonABT6G 1H9 Canada Key Laboratory of Energy Thermal Conversion & Control Southeast University Nanjing210096 China School of Mechanical and Electrical Engineering Guangzhou University Guangzhou510006 China

State and parameter estimation is essential for process monitoring and control. Observability plays an important role in both state and parameter estimation. In simultaneous state and parameter estimation, the parameters are often augmented as extra states of the original system. When the augmented system is observable, various existing state estimation approaches may be used to estimate the states and parameters simultaneously. However, when the augmented system is not observable, how we should proceed to maximally extract the information contained in the measured outputs is not clear. This paper concerns about simultaneous state and parameter estimation when the augmented system is not fully observable. Specifically, we first show how sensitivity analysis is related to observability of a dynamical system, and then illustrate how it may be used to select variables for simultaneous estimation. We also propose a moving horizon state estimation (MHE) design that can use the variable selection results in a natural way. Extensive simulations are carried out to show the efficiency of the proposed approach. Copyright © 2020, The Authors. All rights reserved.

关键词： Sensitivity analysis

Unraveling Ultrafast Photoionization in Hexagonal Boron Nitride

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arXiv 2021年

作者： Xue, Lianjie Liu, Song Hang, Yang Summers, Adam M. Wilson, Derrek J. Wang, Xinya Chen, Pingping Folland, Thomas G. Hachtel, Jordan A. Shi, Hongyu Hosseini-Zavareh, Sajed Das, Suprem R. Lei, Shuting Zhang, Zhuhua Sorensen, Christopher M. Guo, Wanlin Caldwell, Joshua D. Edgar, James H. Blaga, Cosmin I. Trallero-Herrero, Carlos A. Department of Physics Kansas State University ManhattanKS66506 United States Tim Taylor Department of Chemical Engineering Kansas State University ManhattanKS66506 United States J. R. Macdonald Laboratory Department of Physics Kansas State University ManhattanKS66506 United States State Key Laboratory of Mechanics and Control of Mechanical Structures Institute of Nano Science Nanjing University of Aeronautics and Astronautics Nanjing210016 China Advanced Laser Light Source and few-cycle Inc. Institut Nationale de la Recherche Scientifique 1650 Boul. Lionel-Boulet VarennesQCJ3X 1P7 Canada Department of Industrial and Manufacturing Systems Engineering Kansas State University ManhattanKS66506 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States Center for Nanophase Materials Science Oak Ridge National Laboratory Oak Ridge37830 United States Department of Electrical and Computer Engineering Kansas State University ManhattanKS66506 United States Department of Physics University of Connecticut StorrsCT06269 United States

The non-linear response of dielectrics to intense, ultrashort electric fields has been a sustained topic of interest for decades with one of its most important applications being femtosecond laser micro/nano-machining. More recently, renewed interests in strong field physics of solids were raised with the advent of mid-infrared femtosecond laser pulses, such as high-order harmonic generation, optical-field-induced currents, etc. All these processes are underpinned by photoionization (PI), namely the electron transfer from the valence to the conduction bands, on a time scale too short for phononic motion to be of relevance. Here, in hexagonal boron nitride, we reveal that the bandgap can be finely manipulated by femtosecond laser pulses as a function of field polarization direction with respect to the lattice, in addition to the field’s intensity. It is the modification of bandgap that enables the ultrafast PI processes to take place in dielectrics. We further demonstrate the validity of the Keldysh theory in describing PI in dielectrics in the few TW/cm2 regime. © 2021, CC BY.

关键词： Photoionization