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Optimal intervention in transportation networks

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arXiv 2021年

作者： Cianfanelli, Leonardo Como, Giacomo Ozdaglar, Asuman Parise, Francesca Dipartimento di Scienze Matematiche Politecnico di Torino Italy Department of Automatic Control Lund University BOX 118 LundSE-22100 Sweden Department of Electrical Engineering and Computer Science MIT United States Department of Electrical and Computer Engineering Cornell University United States

We study a network design problem (NDP) where the planner aims at selecting the optimal single-link intervention on a transportation network to minimize the travel time under Wardrop equilibrium flows. Our first result is that, if the delay functions are affine and the support of the equilibrium is not modified with interventions, the NDP may be formulated in terms of electrical quantities computed on a related resistor network. In particular, we show that the travel time variation corresponding to an intervention on a given link depends on the effective resistance between the endpoints of the link. We suggest an approach to approximate such an effective resistance by performing only local computation, and exploit it to design an efficient algorithm to solve the NDP. We discuss the optimality of this procedure in the limit of infinitely large networks, and provide a sufficient condition for its optimality. We then provide numerical simulations, showing that our algorithm achieves good performance even if the equilibrium support varies and the delay functions are *** Codes 91A14, 91A43, 91A16, 90B20 Copyright © 2021, The Authors. All rights reserved.

关键词： Travel time

Investigating the origin of optical flares from the TeV blazar S4 0954+65

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arXiv 2023年

作者： Pandey, Ashwani Bachev, Rumen Czerny, Bozena Wiita, Paul J. Gupta, Alok C. Strigachev, Anton Popowicz, Adam Center for Theoretical Physics Polish Academy of Sciences Al.Lotnikov 32/46 WarsawPL-02-668 Poland Institute of Astronomy and NAO Bulgarian Academy of Sciences Sofia1784 Bulgaria Department of Physics The College of New Jersey 2000 Pennington Road EwingNJ08628-0718 United States Manora Peak Nainital263001 India Faculty of Automatic Control Electronics and Computer Science Akademicka 16 Gliwice44-100 Poland

Aims. To investigate the extreme variability properties of the TeV blazar S4 0954+65 using optical photometric and polarization observations carried out between 2017–2023 using 3 ground-based telescopes. Methods. We examined an extensive dataset comprised of 138 intraday (observing duration shorter than a day) light curves (LCs) of S4 0954+65 for flux, spectral, and polarization variations on diverse timescales. For the variable LCs, we computed the minimum variability timescales. We investigated flux-flux correlations and colour variations to look for spectral variations on long-term (several weeks to years) timescales. Additionally, we looked for connections between optical R-band flux and polarization degree. Results. We found significant variations in 59 out of 138 intraday LCs. We detected a maximum change of 0.58±0.11 in V-band magnitude within ∼2.64 hr and a corresponding minimum variability timescale of 18.21±4.87 minutes on 2017 March 25. During the course of our observing campaign, the source brightness changed by ∼4 magnitudes in V and R bands;however, we did not find any strong spectral variations. The slope of the relative spectral energy distribution was 1.37±0.04. The degree of polarization varied from ∼ 3% to 39% during our monitoring. We observed a change of ∼120 degrees in polarization angle within ∼3 hr on 2022 April 13. No clear correlation was found between optical flux and the degree of polarization. Conclusions. The results of our optical flux, colour, and polarization study provide hints that turbulence in the relativistic jet could be responsible for the intraday optical variations in the blazar S4 0954+65. However, the long-term flux variations may be caused by changes in the Doppler factor. Copyright © 2023, The Authors. All rights reserved.

关键词： Polarization

AN EXPLICIT TOTAL LAGRANGIAN FRAGILE POINTS METHOD FOR FINITE DEFORMATION OF HYPERELASTIC MATERIALS

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arXiv 2022年

作者： Mountris, Konstantinos A. Li, Mingjing Schilling, Richard Dong, Leiting Atluri, Satya N. Casals, Alicia Wurdemann, Helge A. Mechanical Engineering University College London London United Kingdom School of Aeronautic Science & Engineering Beihang University Beijing China Barts Heart Centre St Bartholomew's Hospital London United Kingdom Mechanical Engineering Texas Tech University LubbockTX United States Automatic Control & Computer Engineering Universitat Politecnica de Catalunya Barcelona Spain

This research explored a novel explicit total Lagrangian Fragile Points Method (FPM) for finite deformation of hyperelastic materials. In contrast to mesh-based methods, where mesh distortion may pose numerical challenges, meshless methods are more suitable for large deformation modelling since they use enriched shape functions for the approximation of displacements. However, this comes at the expense of extra computational overhead and higher-order quadrature is required to obtain accurate results. In this work, the novel meshless method FPM was used to derive an explicit total Lagrangian algorithm for finite deformation. FPM uses simple one-point integration for exact integration of the Galerkin weak form since it employs simple discontinuous polynomials as trial and test functions, leading to accurate results even with single-point quadrature. The proposed method was evaluated by comparing it with FEM in several case studies considering both the extension and compression of a hyperelastic material. It was demonstrated that FPM maintained good accuracy even for large deformations where FEM failed to converge. Copyright © 2022, The Authors. All rights reserved.

关键词： Integration

Decentralized control barrier functions for coupled multi-agent systems under signal temporal logic tasks

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arXiv 2020年

作者： Lindemann, Lars Dimarogonas, Dimos V. Department of Automatic Control School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm100 44 Sweden

We study the problem of controlling multi-agent systems under a set of signal temporal logic tasks. Signal temporal logic is a formalism that is used to express time and space constraints for dynamical systems. Recent methods to solve the control synthesis problem for single-agent systems under signal temporal logic tasks are, however, subject to a high computational complexity. Methods for multi-agent systems scale at least linearly with the number of agents and induce even higher computational burdens. We propose a computationally-efficient control strategy to solve the multi-agent control synthesis problem that results in a robust satisfaction of a set of signal temporal logic tasks. In particular, a decentralized feedback control law is proposed that is based on time-varying control barrier functions. The obtained control law is discontinuous and formal guarantees are provided by nonsmooth analysis. Simulations show the efficacy of the presented method. Copyright © 2020, The Authors. All rights reserved.

关键词： Multi agent systems

The Influence of Commercial PC Switched Mode Power Supply Interference on the PRIME PLC Performance

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The Influence of Commercial PC Switched Mode Power Supply In...

EMC/SI/PI and EMC Europe Symposium, IEEE International Joint

作者： Waseem El Sayed Paolo Crovetti Piotr Lezynski Robert Smolenski Amr Madi Flavia Grassi Institute of Automatic Control Electronics and Electrical Engineering University of Zielona Gora Poland Electrical Engineering Mathematics & Computer Science (EEMCS) University of Twente Enschede The Netherlands Politecnico di Torino Torino Italy Politecnico di Milano Milano Italy

In the last few decades, the use of power converters has become essential in the smart grid environment. Consequently, this leads to the presence of a high-level of conducted electromagnetic interference between the smart grid elements. This paper studies the effect of two power converter modulation techniques: conventional fixed-frequency modulation and spread-spectrum modulation, on the performance of the Power Line Communication (PLC) signal. The paper presents a practical implementation of the system and discusses the results for different operating scenarios.

关键词： Channel capacity OFDM Electromagnetic interference Switched mode power supplies Power line communications Modulation Electromagnetic compatibility

Hybrid Sensor Network for Monitoring Environmental Parameters

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Hybrid Sensor Network for Monitoring Environmental Parameter...

Mediterranean Conference on control and Automation (MED)

作者： Dan Popescu Emilian Vlasceanu Marius Dima Florin Stoican Loretta Ichim Faculty of Automatic Control and Computer Science University Politehnica of Bucharest Bucharest Romania AFT R&D Bucharest Romania

ISBN: (数字)9781728157429

ISBN: (纸本)9781728157436

The paper proposes a cheap hybrid ground-air sensor network for environmental parameter measurements. The ground sensors are grouped into clusters, each cluster having several sensory nodes connected to a cluster head that sends the relevant data to the aerial, mobile nodes - unmanned aerial vehicles (UAVs). Thus, using optimal trajectories, the UAVs are used both for measuring directly environmental parameters, as well as for collecting data from ground sensors. The authors present the modules' implementation of the hybrid system: ordinary sensory nodes, cluster heads, ground control stations, communication modems and UAV platforms. Finally, the performances of the realized hybrid network are analyzed from multiple points of view: energy consumption, time, and data acquisition efficiency.

关键词： Unmanned aerial vehicles Trajectory Wireless sensor networks Monitoring Servers Task analysis Data acquisition

Distributed formation control for manipulator end-effectors

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arXiv 2021年

作者： Wu, Haiwen Jayawardhana, Bayu De Marina, Hector Garcia Xu, Dabo Engineering and Technology Institute Groningen Faculty of Science and Engineering University of Groningen Groningen9747 AG Netherlands Department of Computer Architecture and Automatic Control Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain School of Automation Nanjing University of Science and Technology Nanjing210094 China

We present three classes of distributed formation controllers for achieving and maintaining the 2D/3D formation shape of manipulator end-effectors to cope with different scenarios due to availability of modeling parameters. We firstly present a distributed formation controller for manipulators whose system parameters are perfectly known. The formation control objective is achieved by assigning virtual springs between end-effectors and by adding damping terms at joints, which provides a clear physical interpretation of the proposed solution. Subsequently, we extend it to the case where manipulator kinematic and system parameters are not exactly known. An extra integrator and an adaptive estimator are introduced for gravitational compensation and stabilization, respectively. Simulation results with planar manipulators and with seven degree-of-freedom humanoid manipulator arms are presented to illustrate the effectiveness of the proposed approach. Copyright © 2021, The Authors. All rights reserved.

关键词： Manipulators

Distributed formation control of manipulators' end-effector with internal model-based disturbance rejection

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arXiv 2021年

作者： Wu, Haiwen Jayawardhana, Bayu de Marina, Hector Garcia Xu, Dabo Engineering and Technology Institute Groningen Faculty of Science and Engineering University of Groningen Groningen9747 AG Netherlands Department of Computer Architecture and Automatic Control Faculty of Physics Universidad Complutense de Madrid Madrid28040 Spain The School of Automation Nanjing University of Science and Technology Nanjing210094 China

This paper addresses the problem of end-effector formation control for manipulators that are subjected to external disturbances: input disturbance torques and disturbance forces at each end-effector. The disturbances are assumed to be non-vanishing and are superposition of finite number of sinusoidal and step signals. The formation control objective is achieved by assigning virtual springs between end-effectors, by adding damping terms at joints, and by incorporating internal model-based dynamic compensators to counteract the effect of the disturbances;all of which presents a clear physical interpretation of the proposed approach. Simulation results are presented to illustrate the effectiveness of the proposed approach. © 2021, CC BY.

关键词： End effectors

Optimisation of a siamese neural network for real-time energy efficient object tracking

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arXiv 2020年

作者： Przewlocka, Dominika Wasala, Mateusz Szolc, Hubert Blachut, Krzysztof Kryjak, Tomasz Embedded Vision Systems Group Computer Vision Laboratory Department of Automatic Control and Robotics AGH University of Science and Technology Krakow Poland

In this paper the research on optimisation of visual object tracking using a Siamese neural network for embedded vision systems is presented. It was assumed that the solution shall operate in real-time, preferably for a high resolution video stream, with the lowest possible energy consumption. To meet these requirements, techniques such as the reduction of computational precision and pruning were considered. Brevitas, a tool dedicated for optimisation and quantisation of neural networks for FPGA implementation, was used. A number of training scenarios were tested with varying levels of optimisations - from integer uniform quantisation with 16 bits to ternary and binary networks. Next, the influence of these optimisations on the tracking performance was evaluated. It was possible to reduce the size of the convolutional filters up to 10 times in relation to the original network. The obtained results indicate that using quantisation can significantly reduce the memory and computational complexity of the proposed network while still enabling precise tracking, thus allow to use it in embedded vision systems. Moreover, quantisation of weights positively affects the network training by decreasing overfitting. Copyright © 2020, The Authors. All rights reserved.

关键词： Field programmable gate arrays (FPGA)