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PATH PLANNING FOR MOBILE MANIPULATORS FOR MULTIPLE TASK EXECUTION

IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION 1991年第3期7卷 403-408页

作者： CARRIKER, WF KHOSLA, PK KROGH, BH Laboratory for Automated Systems and Information Processing Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA USA

We consider the planning problem for a mobile manipulator system that must perform a sequence of tasks defined by position, orientation, force, and moment vectors at the end-effector. Each task can be performed in multiple configurations due to the redundancy introduced by mobility. We formulate the planning problem as an optimization problem in which the decision variables for mobility (base position) are separated from the manipulator joint angles in the cost function. The resulting numerical problem is nonlinear with nonconvex, unconnected feasible regions in the decision space. Simulated annealing is proposed as a general solution method for obtaining near-optimal results. The problem formulation and numerical solution by simulated annealing are illustrated for a manipulator system with three degrees of freedom mounted on a base with two degrees of freedom. These results are compared with results obtained by conventional nonlinear programming techniques customized for the particular example system.

关键词： Path planning Simulated annealing Cost function Numerical simulation Space stations Robotics and automation Manipulators Trajectory Constraint optimization Ear

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PERFORMANCE EVALUATION OF THE CONSUMER ELECTRONIC BUS

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 1990年第4期36卷 949-953页

作者： PAKKAM, SR MANIKOPOULOS, CN Intelligent Systems Laboratory Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

This paper reports on the results of a simulation study undertaken to evaluate the performance of the Consumer Electronic Bus (CEBUS) under various traffic patterns and especially under large traffic generated by high priority nodes. The CEBUS is based on the ISO/OSI model of layered architecture. The simulation results have shown that, when the throughput of the network is small (30%), the delay is bounded for all messages of all priorities. As the throughput of the network increases to more than 70%, due to an increasing number of high priority messages, the lower priority messages get queued at their nodes. It is also shown that the delay can be bounded, when needed, by assigning high priority status to nodes generating messages with urgent communications and lower priority status to nodes sending messages which do not require immediate response.

关键词： Consumer electronics Traffic control Telecommunication traffic ISO Throughput Communication standards Multiaccess communication Laboratories Computational modeling computer simulation

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METAL CONTACTS TO GALLIUM NITRIDE

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APPLIED PHYSICS LETTERS 1993年第22期62卷 2859-2861页

作者： FORESI, JS MOUSTAKAS, TD Molecular Beam Epitaxy Laboratory Department of Electrical Computer and Systems Engineering Boston University Boston Massachusetts 02215

We report measurements on the nature of aluminum and gold contacts to GaN. The GaN films were deposited onto the R-plane of sapphire substrates by molecular beam epitaxy and are autodoped n-type. Metal contacts were deposited by evaporation and were patterned photolithographically. Current-voltage characterization shows that the as-deposited aluminum contacts are ohmic while the as-deposited gold contacts are rectifying. The gold contacts become ohmic after annealing at 575-degrees-C, a result attributed to gold diffusion. The specific contact resistivity of the ohmic aluminum and gold contacts were found by transfer length measurements to be of device quality (10(-7)-10(-8) OMEGA m2). The results of these studies suggest a direct correlation between barrier height and work function of the metal, consistent with the strong ionic character of GaN.

关键词： GALLIUM NITRIDES METAL?SEMICONDUCTOR CONTACTS GOLD ALUMINIUM CONTACT POTENTIAL IV CHARACTERISTIC ANNEALING DIFFUSION BARRIER HEIGHT WORK FUNCTIONS

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INTENSITY DEPENDENCE OF PHOTOLUMINESCENCE IN GAN THIN-FILMS

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APPLIED PHYSICS LETTERS 1994年第3期64卷 336-338页

作者： SINGH, R MOLNAR, RJ UNLU, MS MOUSTAKAS, TD Molecular Beam Epitaxy Laboratory Department of Electrical Computer and Systems Engineering Boston University Boston Massachusetts 02215

We report the intensity dependence of band-gap and midgap photoluminescence in GaN films grown by electron cyclotron resonance (ECR) microwave plasma-assisted molecular beam epitaxy. We find that the band-gap luminescence depends linearly while the midgap luminescence has a nonlinear dependence on the incident light intensity. These data were compared with a simple recombination model which assumes a density of recombination centers 2.2 eV below the conduction band edge. The concentration of these centers is higher in films grown at higher microwave power in the ECR plasma.

关键词： GALLIUM NITRIDES PHOTOLUMINESCENCE MOLECULAR BEAM EPITAXY ENERGY GAP DEFECT STATES RECOMBINATION SPECTRAL ANALYSIS ECR HEATING PLASMA

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ELECTRON-TRANSPORT MECHANISM IN GALLIUM NITRIDE

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APPLIED PHYSICS LETTERS 1993年第1期62卷 72-74页

作者： MOLNAR, RJ LEI, T MOUSTAKAS, TD Molecular Beam Epitaxy Laboratory Department of Electrical Computer and Systems Engineering Boston University Boston Massachusetts 02215

The electron transport mechanism in autodoped gallium nitride films grown by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy was investigated by studying the temperature dependence of the Hall coefficient and resistivity on samples with various concentrations of autodoping centers. The Hall coefficients go through a maximum as the temperature is lowered from 300 K and then saturate at lower temperatures. The resistivities in the same temperature range initially increase exponentially and then saturate at lower temperatures. These findings are accounted for if a significant fraction of electron transport, even at room temperature, takes place in the autodoping centers and that conduction through these centers becomes dominant at lower temperatures. The activation energy of these centers was found to be on the order of 20-30 meV. When the concentration of the autodoping centers becomes smaller than that of deep compensating defects, the material becomes semi-insulating and transport by hopping in the compensating defects becomes dominant.

关键词： GALLIUM NITRIDES VACANCIES ELECTRON MOBILITY MOLECULAR BEAM EPITAXY MAGNETORESISTANCE TEMPERATURE DEPENDENCE DEFECT STATES ACTIVATION ANALYSIS

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Consensus Control for Discrete-Time Stochastic Multiagent systems Under a Multiple Description Coding Mechanism

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IEEE systems Journal 2025年

作者： Wang, Licheng Wang, Zidong Qian, Wei Du, Shuxin Shanghai University of Electric Power College of Automation Engineering Shanghai 200090 China Brunel University London Department of Computer Science Uxbridge UB8 3PH United Kingdom Henan Polytechnic University School of Electrical Engineering and Automation Jiaozuo 454000 China Huzhou University Huzhou Key Laboratory of Intelligent Sensing and Optimal Control for Industrial Systems School of Engineering Huzhou 313000 China

This article addresses the consensus control problem for a specific class of discrete-time stochastic multiagent systems (MASs). When transmitting the local measurement output to the local controller and neighboring agents, a multiple description coding (MDC) scheme is introduced to reduce the communication burden and enhance data transmission reliability in a resource-constrained environment. The MDC scheme encodes each signal into two descriptions, which are then transmitted through separate channels, and decoding schemes are employed to address the different characteristics of the arrival of the two descriptions, ensuring the boundedness of the decoding error. The proposed consensus control scheme uses the relative decoded measurement errors between local agents and their neighbors. The aim is to design an output-feedback control scheme that ensures the error dynamics of the controlled MAS reach exponentially mean-square boundedness. Sufficient conditions are established for the existence of the controllers through stochastic analysis techniques, and the desired controller gains are parameterized using the feasibility of certain matrix inequalities. The effectiveness of the proposed coding-decoding-based consensus control scheme is verified through a numerical simulation. © 2007-2012 IEEE.

关键词： Consensus control multiagent systems (MASs) multiple description coding (MDC) packet dropout stochastic systems

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TRANSPUTER CONTROL OF A FLEXIBLE ROBOT LINK

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MICROPROCESSORS AND MICROsystems 1989年第3期13卷 227-232页

作者： STAVENUITER, ACJ TERREEHORST, G BAKKERS, AWP Control Systems and Computer Engineering Laboratory Department of Electrical Engineering University of Twente PO Box 217 7500 AE Enschede The Netherlands

The applicability of transputers in control systems is investigated. This is done by implementing a controller for a flexible robot arm with one degree of freedom on a system consisting of an IBM-AT and four transputers. It is found that a control system with transputers offers a great improvement compared with conventional digital control systems. Transputers can solve the common problem in control practice, i.e. having very sophisticted controllers but not being able to implement them because they need too much computing time. However, transputers are not an optimal solution for more sophisticated control systems because of shortcomings in the scheduling mechanism.

关键词： control systems robots transputers

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An overview of synthetic-aperture image reconstruction algorithms for GPR imaging with pulse-echo and step-frequency FMCW systems

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Journal of Environmental and engineering Geophysics 2003年第2期8卷 105-113页

作者： Lee, Hua Imaging Systems Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106

The ground-penetrating radar (GPR) systems currently deployed in field applications can be classified into two major types, pulse-echo and step-frequency frequency modulated continuous-wave (FMCW) devices, corresponding to the distinct features of the illumination waveforms. With the addition of synthetic-aperture scans, both versions can be directly applied to high-resolution tomographic imaging. This paper presents the tomographic image reconstruction algorithms for these two operating modalities based on one single framework of backward propagation image formation. In addition to the theoretical analysis and mathematical modeling, this paper presents the algorithm structures for both types of systems as well as results from full-scale field experiments.

关键词： Environmental engineering

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Partial discharges in epoxy resin voids and the interpretational possibilities and limitations of Pedersen's model

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electrical engineering 1997年第2期80卷 105-110页

作者： Danikas, MG Adamidis, G Electric Energy Systems Laboratory Democritus University of Thrace Department of Electrical and Computer Engineering Xanthi Greece

Contents Partial discharges take place, among others, inside voids enclosed in insulations. The partial discharge behaviour of epoxy resin samples is studied with the aid of a recently developed streamer partial discharge model (Pedersen's model) and its relation to the modem Pulse Height Analysis and Phase Resolved Measurement techniques is investigated. Furthermore, some relations based on Pedersen's model are deduced. The advantages and disadvantages of the aforementioned model are analysed. Scanning electron microscope photographs show the nature of the deterioration of the void walls due to the partial discharges. The question whether initiation of the treeing phenomenon leading to breakdown from an enclosed spherical void is possible, is also investigated.

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Are Domain Generalization Benchmarks with Accuracy on the Line Misspecified?

arXiv

引用

arXiv 2025年

作者： Salaudeen, Olawale Chiou, Nicole Weng, Shiny Koyejo, Sanmi Department of Electrical Engineering and Computer Science Laboratory for Information and Decision Systems Massachusetts Institute of Technology CambridgeMA02139 United States Department of Computer Science Stanford University StanfordCA94305 United States

Spurious correlations are unstable statistical associations that hinder robust decision-making. Conventional wisdom suggests that models relying on such correlations will fail to generalize out-of-distribution (OOD), particularly under strong distribution shifts. However, a growing body of empirical evidence challenges this view, as naive in-distribution empirical risk minimizers often achieve the best OOD accuracy across popular OOD generalization benchmarks. In light of these counterintuitive results, we propose a different perspective: many widely used benchmarks for assessing the impact of removing spurious correlations on OOD generalization are misspecified. Specifically, they fail to include shifts in spurious correlations that meaningfully degrade OOD generalization, making them unsuitable for evaluating the benefits of removing such correlations. Consequently, we establish conditions under which a distribution shift can reliably assess a model’s reliance on spurious correlations. Crucially, under these conditions, we provably should not observe a strong positive correlation between in-distribution and out-of-distribution accuracy—often referred to as accuracy on the line. Yet, when we examine state-of-the-art OOD generalization benchmarks, we find that most exhibit accuracy on the line, suggesting they do not effectively assess robustness to spurious correlations. Our findings expose a limitation in current benchmarks evaluating algorithms for domain generalization, i.e., learning predictors that do not rely on spurious correlations. Our results (i) highlight the need to rethink how we assess robustness to spurious correlations, (ii) identify existing well-specified benchmarks the field should prioritize, and (iii) enumerate strategies to ensure future benchmarks are well-specified. © 2025, CC BY-NC-ND.

关键词： Decision making

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