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arXiv 2018年

作者： Wang, Gang Giannakis, Georgios B. Chen, Jie Digital Technology Center Department of Electrical and Computer Engineering University of Minnesota MinneapolisMN55455 United States State Key Lab of Intelligent Control Decision of Complex Systems School of Automation Beijing Institute of Technology Beijing100081 China Tongji University Shanghai200092 China

Neural networks with REctified Linear Unit (ReLU) activation functions (a.k.a. ReLU networks) have achieved great empirical success in various domains. Nonetheless, existing results for learning ReLU networks either pose assumptions on the underlying data distribution being e.g. Gaussian, or require the network size and/or training size to be sufficiently large. In this context, the problem of learning a two-layer ReLU network is approached in a binary classification setting, where the data are linearly separable and a hinge loss criterion is adopted. Leveraging the power of random noise perturbation, this paper presents a novel stochastic gradient descent (SGD) algorithm, which can provably train any single-hidden-layer ReLU network to attain global optimality, despite the presence of infinitely many bad local minima, maxima, and saddle points in general. This result is the first of its kind, requiring no assumptions on the data distribution, training/network size, or initialization. Convergence of the resultant iterative algorithm to a global minimum is analyzed by establishing both an upper bound and a lower bound on the number of non-zero updates to be performed. Moreover, generalization guarantees are developed for ReLU networks trained with the novel SGD leveraging classic compression bounds. These guarantees highlight a key difference (at least in the worst case) between reliably learning a ReLU network as well as a leaky ReLU network in terms of sample complexity. Numerical tests using both synthetic data and real images validate the effectiveness of the algorithm and the practical merits of the theory. Copyright © 2018, The Authors. All rights reserved.

关键词： Stochastic systems

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Modeling and simulation of air-gapped current transformer based on Preisach Theory

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Protection and control of Modern Power systems 2017年第1期2卷 111-121页

作者： Ya Hui Wu Xin Zhou Dong Sohrab Mirsaeidi State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Current Transformer(CT)modeling,by which CT’s characteristics can be studied has a significant importance in CT selection and *** spite of numerous studies about closed-core CT model,only a few works have been conducted on air-gapped ones with the following problems:models of which required data is easily-accessible,have poor simulations of magnetization process;on the contrary,models which have satisfactory simulations,are hard to be established because of the hard-to-get required ***,based on Preisach Theory,a novel air-gapped CT model is deduced from the closed core CT *** proposed model is accurate and can be established *** saturation and remanence properties of closed-core CT and air-gapped CT are simulated and compared.

关键词： CT modeling Air gap Preisach Theory Saturation Remanence

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Optimal voltage control for loss minimization based on sequential convex programming

Optimal voltage control for loss minimization based on seque...

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2016 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe 2016

作者： Necoara, Ion Nedelcu, Valentin Clipici, Dragos Toma, Lucian Bulac, Constantin Automatic Control and Systems Engineering Department University Politehnica Bucharest Romania Electrical Power Systems Department University Politehnica Bucharest Romania

ISBN: (纸本)9781509033584

This paper focuses on the active power loss minimization by optimal voltage control in a power system using a new optimization algorithm. The cost function is assumed to be convex. The algorithm we propose to address the numerical solution of this problem is based on the exploitation of the convex problem structure using a sequential convex programming framework that linearizes the nonlinear power balance constraints at each iteration. The convex subproblem is then solved using a dual fast gradient method. We provide mathematical guarantees for the linear convergence of the algorithm towards a local solution. This approach allows an optimal voltage for each bus, while achieving the (local) economical optimum of the whole power grid. The newly developed algorithm can be run over large electricity networks, as we show on several numerical simulations using the classical IEEE bus test cases. © 2016 IEEE.

关键词： Convex optimization

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Robust optimization of water-flooding in oil reservoirs using risk management tools

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IFAC-PapersOnLine 2016年第7期49卷 133-138页

作者： Siraj, M. Mohsin Van den Hof, Paul M.J. Jansen, Jan Dirk Electrical Engineering Control Systems group Eindhoven University of Technology Netherlands Department of Geoscience and Engineering Delft University of Technology Netherlands

The theory of risk provides a systematic approach to handling uncertainty with well-defined risk and deviation measures. As the model-based economic optimization of the water-flooding process in oil reservoirs suffers from high levels of uncertainty, the concepts from the theory of risk are highly relevant. In this paper, the main focus is to offer an asymmetric risk management, i.e., to maximize the lower tail (worst cases) of the economic objective function distribution without heavily compromising the upper tail (best cases). Worst-case robust optimization and Conditional Value-at-Risk (CVaR) risk measures are considered with geological uncertainty to improve the worst case(s). Furthermore, a deviation measure, semi-variance, is also used with both geological and economic uncertainty to maximize the lower tail. The geological uncertainty is characterized by an ensemble of geological model realizations and the economic uncertainty is defined by an ensemble of varying oil price scenarios. © 2016

关键词： Risk assessment Distribution functions Floods Geology Oil well flooding Optimization Petroleum reservoir engineering Reservoir management Reservoirs (water) Risk management Value engineering Conditional Value at Risk Economic objective function Economic optimization Economic uncertainty Geological uncertainty Handling uncertainty Risk measures Robust optimization

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A hybrid systems framework for multi agent task planning and control

A hybrid systems framework for multi agent task planning and...

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American control Conference

作者： Maria Guinaldo Dimos V. Dimarogonas Department of Computer Sciences and Automatic Control School of Computer Engineering UNED Madrid Spain ACCESS Linneaeus Center School of Electrical Engineering KTH Stockholm Sweden

ISBN: (纸本)9781509045839

In this paper, we investigate the coordination of a multi-agent system to achieve a high level plan. In, particular, we assume that this planning is decomposed in a sequence of simple control objectives. The coordination is carried out through event-based communications between the agents, and distributed control laws are synthesized to achieve each control objective according to a time-constraint. All the elements (planning, motion, and communication) are integrated in a hybrid systems framework, which also allows to conclude about the achievement of the high level plan.

关键词： hybrid systems Agents Multi-agent systems Communication Research Planning Standing Orders Frameworks communication between animals Event-based

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Collaborative target-tracking control using multiple autonomous fixed-wing UAVs with constant speeds: Theory and experiments

arXiv

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arXiv 2018年

作者： Sun, Zhiyong Garcia de Marina, Héctor Seyboth, Georg S. Anderson, Brian D.O. Yu, Changbin Research School of Engineering Australian National University CanberraACT2601 Australia Hangzhou310018 China Department of Automatic Control Lund University Lund Sweden Unmanned Aerial Systems centre Maersk Mc-Kinney Moller Institute University of Southern Denmark Odense MDK-5230 Denmark Robert Bosch Automotive Steering GmbH

—This paper considers a collaborative tracking control problem using a group of fixed-wing UAVs with constant and non-identical speeds. The dynamics of fixed-wing UAVs are modelled by unicycle-type equations, with nonholonomic constraints by assuming that UAVs fly at constant attitudes in the nominal operation mode. The control focus is on the design of a collective tracking controller such that all fixed-wing UAVs as a group can collaboratively track a desired target’s position and velocity. We construct a reference velocity that includes both the target’s velocity and position as feedback, which is to be tracked by the group centroid. In this way, all vehicles’ headings are controlled such that the group centroid follows a reference trajectory that successfully tracks the target’s trajectory. We consider three cases of reference velocity tracking: the constant velocity case, the turning velocity case with constant speed, and the time-varying velocity case. An additive spacing controller is further devised to ensure that all vehicles stay close to the group centroid trajectory. Trade-offs and performance limitations of the target tracking control due to the constant-speed constraint are also discussed in detail. Experimental results with three fixed-wing UAVs tracking a target rotorcraft are shown to validate the effectiveness and performance of the proposed tracking controllers. Copyright © 2018, The Authors. All rights reserved.

关键词： Fixed wings

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On control Structure Design for a Walking Beam Furnace

On Control Structure Design for a Walking Beam Furnace

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Mediterranean Conference on control and Automation

作者： H. Jafari M. Castano T. Gustafsson G. Nikolakopoulos Control Engineering group Devision of Signals and Systems Department of Computer Science Electrical and Space Engineering Lule? University of Technology Sweden

ISBN: (纸本)9781509045341

The aim of this article is to introduce a novel sparse controller design for the temperature control of an experimental walking beam furnace in steel industry. Adequate tracking of temperature references is essential for the quality of the heated slabs. However, the design of the temperature control is hindered by the multivariable (non-square) dynamic behavior of the furnace. These dynamics include significant loop interactions and time delays. Furthermore, a novel data-driven model, based on real life experimental data that relies on a subspace state representation in a closed loop approach is introduced. In the sequel, the derived model is utilized to investigate the controller's structure. By applying the relative gain array approach a decentralized feedback controller is designed. However, in spite of the optimal and sparse design of the controller, there exists interaction between loops. By analyzing the interaction between the inputs-outputs with the Σ2 Gramian-based interaction methodology, a decoupled multi-variable controller is implied. The simulation result, based on the experimental modeling of the furnace, shows that the controller can successfully decrease the interaction between the loops and track the reference temperature set-points.

关键词： control Structure Walking Beam Furnace

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Bilateral teleoperation of multiple robots under scheduling communication

arXiv

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arXiv 2018年

作者： Li, Yuling Liu, Kun He, Wei Yin, Yixin Johansson, Rolf Zhang, Kai School of Automation and Electrical Engineering University of Science and Technology Beijing Beijing100083 China Key Laboratory of Knowledge Automation for Industrial Processes Ministry of Education Beijing100083 China School of Automation Beijing Institute of Technology Beijing100081 China Department of Automatic Control Lund University P.O. Box 118 Lund22100 Sweden

In this paper, bilateral teleoperation of multiple slaves coupled to a single master under scheduling communication is investigated. The sampled-data transmission between the master and the multiple slaves is fulfilled over a delayed communication network, and at each sampling instant, only one slave is allowed to transmit its current information to the master side according to some scheduling protocols. To achieve the masterslave synchronization, Round-Robin scheduling protocol and TryOnce-Discard scheduling protocol are employed, respectively. By designing a scheduling-communication-based controller, some sufficient stability criteria related to the controller gain matrices, sampling intervals, and communication delays are obtained for the closed-loop teleoperation system under Round-Robin and Try-Once-Discard scheduling protocols, respectively. Finally, simulation studies are given to validate the effectiveness of the proposed results. Copyright © 2018, The Authors. All rights reserved.

关键词： Remote control

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Feasibility analysis and application of graph processing in Gauss and Newton-Raphson power flow calculation

Feasibility analysis and application of graph processing in ...

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2017 IEEE Conference on Energy Internet and Energy System Integration, EI2 2017

作者： Wang, Di Guo, Qinglai Su, Zhuo State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing100084 China Guangdong Province Power Dispatching and Control Center China Southern Power Grid Guangzhou Guangdong Province510600 China

ISBN: (纸本)9781538614273

Graph processing is a new kind of parallel computing framework with superiority in dealing with massive data with graph structure and complex relevance. In the power system, the grid has a natural graph structure, and the relevance between bus states is very strong. Moreover, the rapid development and application of information technology has also brought the explosive growth of the amount of data for the power system. This paper discusses the application of graph processing in some power flow calculation methods. Firstly, the features of graph processing and the feasibility of some existing power flow algorithms in the graph processing system are analyzed in detail. Then the triangular decomposition of matrix and the forward substitution based on graph processing are proposed. Lastly, cases of different sizes are presented to verify the correctness of theoretical analysis and the features of graph processing. © 2017 IEEE.

关键词： Matrix algebra

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Balanced truncation of networked linear passive systems?

arXiv

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arXiv 2017年

作者： Cheng, Xiaodong Scherpen, Jacquelien M.A. Besselink, Bart Jan C. Willems Center for Systems and Control Faculty of Science and Engineering University of Groningen Netherlands Control Systems Group Department of Electrical Engineering Eindhoven University of Technology Netherlands

This paper studies model order reduction of multi-agent systems consisting of identical linear passive subsystems, where the interconnection topology is characterized by an undirected weighted graph. Balanced truncation based on a pair of specifically selected generalized Gramians is implemented on the asymptotically stable part of the full-order network model, which leads to a reduced-order system preserving the passivity of each subsystem. Moreover, it is proven that there exists a coordinate transformation to convert the resulting reduced-order model to a state-space model of Laplacian dynamics. Thus, the proposed method simultaneously reduces the complexity of the network structure and individual agent dynamics, and it preserves the passivity of the subsystems and the synchronization of the network. Moreover, it allows for the a priori computation of a bound on the approximation error. Finally, the feasibility of the method is demonstrated by an example. Copyright © 2017, The Authors. All rights reserved.

关键词： Matrix algebra

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