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Optimization of a fertilizer spreading process

MATHEMATICS AND COMPUTERS IN SIMULATION 2009年第10期79卷 3099-3109页

作者： Koko, Jonas Virin, Teddy Univ Clermont Ferrand CNRS LIMOS UMR 6158 F-63177 Aubiere France Cemagref UR TSCF F-03150 Domaine Des Palaquins Montoldre France

An optimization method for accurate fertilizer application by centrifugal spreader is described. The cost functional is a distance between a prescribed dose and the distributed dose. The distributed dose is computed using a simplified spread pattern and the unknowns of the problem are three time-dependent parameters of the spreader: the average (distribution) center. the average (distribution) angle and the mass flow rate. In order to take into account the mechanical limits of the device. constraints are introduced in the form of bounds on the parameter functions and their time derivatives. Numerical experiments show that application errors can be significantly reduced for parallel tracks within a main field body. (C) 2008 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： Infinite-dimensional optimization nonlinear programming Centrifugal spreaders

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On the asymmetric eigenvalue complementarity problem

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OPTIMIZATION METHODS & SOFTWARE 2009年第4-5期24卷 549-568页

作者： Judice, Joaquim J. Sherali, Hanif D. Ribeiro, Isabel M. Rosa, Silverio S. Univ Beira Interior Dept Matemat Covilha Portugal Univ Coimbra Dept Matemat P-3000 Coimbra Portugal Inst Telecomunicacoes Coimbra Portugal Virginia Polytech Inst & State Univ Grado Dept Ind & Syst Engn Blacksburg VA 24061 USA Univ Porto Fac Engn Dept Civil Engn Seccao Matemat P-4100 Oporto Portugal

In this paper, we discuss the eigenvalue complementarity problem (EiCP) where at least one of its defining matrices is asymmetric. A sufficient condition for the existence of a solution to the EiCP is established. The EiCP is shown to be equivalent to finding a global minimum of an appropriate merit function on a convex set defined by linear constraints. A sufficient condition for a stationary point of this function on to be a solution of the EiCP is presented. A branch-and-bound procedure is developed for finding a global minimum of this merit function on . In addition, a sequential enumerative algorithm for the computation of the minimum and the maximum eigenvalues is also discussed. Computational experience is included to highlight the efficiency and efficacy of the proposed methodologies to solve the asymmetric EiCP.

关键词： eigenvalue complementarity extreme eigenvalues branch-and-bound global optimization nonlinear programming

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Optimal power split in a hybrid electric vehicle using direct transcription of an optimal control problem

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MATHEMATICS AND COMPUTERS IN SIMULATION 2009年第6期79卷 1959-1970页

作者： Perez, Laura V. Pilotta, Elvio A. Univ Nacl Rio Cuarto Fac Ingn Grp Elect Aplicada Cordoba Argentina Univ Nacl Rio Cuarto CONICET CIEM Fac Matemat Astron & Fis Cordoba Argentina

To efficiently operate electromechanical systems powered by two energy sources, it is necessary to determine the instantaneous power split between sources in order to minimize the energy consumption of the whole system. In this work, this problem is posed as it nonlinear finite horizon optimal control problem with control and state constraints and is solved using a direct transcription approach. The problem is fully discretized in time and the resulting finite dimensional optimization problem is solved using a nonlinear programming code. This paper describes the application of direct transcription to the case of the hybrid electric vehicle (HEV) being developed in the Applied Electronics Group (GEA) at the University of Rio Cuarto. The statement and discretization of the control problem, the setting for using the nonlinear programming code and several examples and comparisons with those obtained by other approaches are described. (C) 2007 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： Direct transcription Optimal control with constraints nonlinear programming Hybrid electric vehicles

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Linear Processing and Sum Throughput in the Multiuser MIMO Downlink

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2009年第5期8卷 2652-2661页

作者： Tenenbaum, Adam J. Adve, Raviraj S. Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

We consider linear precoding and decoding in the downlink of a multiuser multiple-input, multiple-output (MIMO) system, wherein each user may receive more than one data stream. We propose several mean squared error (MSE) based criteria for joint transmit-receive optimization and establish a series of relationships linking these criteria to the signal-to-interference-plus-noise ratios of individual data streams and the information theoretic channel capacity under linear minimum MSE decoding. In particular, we show that achieving the maximum sum throughput is equivalent to minimizing the product of MSE matrix determinants (PDetMSE). Since the PDetMSE minimization problem does not admit a computationally efficient solution, a simplified scalar version of the problem is considered that minimizes the product of mean squared errors (PMSE). An iterative algorithm is proposed to solve the PMSE problem, and is shown to provide near-optimal performance with greatly reduced computational complexity. Our simulations compare the achievable sum rates under linear precoding strategies to the sum capacity for the broadcast channel.

关键词： Adaptive arrays adaptive modulation diversity methods information rates MIMO systems nonlinear programming optimization methods least mean square methods space division multiplexing

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Differential evolution algorithm for static and multistage transmission expansion planning

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IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第4期3卷 365-384页

作者： Sum-Im, T. Taylor, G. A. Irving, M. R. Song, Y. H. Brunel Univ Brunel Inst Power Syst Sch Engn & Design Uxbridge UB8 3PH Middx England Univ Liverpool Dept Elect Engn & Elect Liverpool L69 3GJ Merseyside England

A novel differential evolution algorithm (DEA) is applied directly to the DC power flow-based model in order to efficiently solve the problems of static and multistage transmission expansion planning (TEP). The purpose of TEP is to minimise the transmission investment cost associated with the technical operation and economical constraints. Mathematically, long-term TEP using the DC model is a mixed integer nonlinear programming problem that is difficult to solve for large-scale real-world transmission networks. In addition, the static TEP problem is considered both with and without the resizing of power generation in this research. The efficiency of the proposed method is initially demonstrated via the analysis of low, medium and high complexity transmission network test cases. The analysis is performed within the mathematical programming environment of MATLAB using both DEA and conventional genetic algorithm and a detailed comparative study is presented.

关键词： DC power flow-based model power transmission planning Power transmission, distribution and supply Power system planning and layout Power system management, operation and economics Optimisation techniques nonlinear programming integer programming large-scale transmission network DEA investment cost power transmission economics integer nonlinear programming evolutionary computation MATLAB environment multistage transmission expansion planning load flow static TEP economical constraint costing differential evolution algorithm

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An Experimental Study of the GAMS/AlphaECP MINLP Solver

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2009年第15期48卷 7337-7345页

作者： Lastusilta, Toni Bussieck, Michael R. Westerlund, Tapio Abo Akad Univ Proc Design & Syst Engn Lab FIN-20500 Turku Finland GAMS Software GmbH D-50933 Cologne Germany

The development of methods to solve mixed-integer nonlinear programming (MINLP) problems has given rise to new solvers and improved the current ones. In this Article, the focus is set on the MINLP solvers in the General Algebraic Modeling System (GAMS) and especially GAMS/AlphaECP. In this Article, a comprehensive comparison of the MINLP solvers is made. In June 2007, GAMS introduced new MINLP solvers: CoinBonmin, AlphaECP, and LINDOGlobal. A description of the improvements made in the second half of 2007 to AlphaECP is given, and the performance of the MINLP solvers in GAMS is examined. Furthermore, the performance of AlphaECP for both MINLP and nonlinear programming (NLP) problems is studied, in conjunction with different subsolvers. Two large collections of problems, MINLPLib and GLOBALLib, are used for all solver performance comparisons.

关键词： nonlinear programming SCIENTIFIC experimentation MATHEMATICAL models COMPARATIVE studies MATHEMATICAL programming programming languages (Electronic computers) INTEGER programming SYSTEMS engineering SYSTEMS design

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Symmetric AC fuzzy power flow model

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2009年第3期197卷 1012-1018页

作者： Gouveia, Eduardo M. Matos, Manuel A. Polytech Inst Viseu ESTV Sch Technol Viseu P-3504510 Viseu Portugal Univ Porto Fac Engn INESC Porto FEUP P-4200465 Oporto Portugal

Power flow calculations are one of the most important computational tools for planning and operating electric power systems. After the stabilization of the deterministic power flow calculation methods, the need to capture uncertainty in load definition lead first to the development of probabilistic models, and later to fuzzy approaches able to deal with qualitative declarations and other non-probabilistic information about the value of the loads. Present fuzzy power flow (FPF) calculations use typically incremental techniques, in order to obtain a good approximation of the fuzzy state variables. However, these models and procedures are not entirely satisfactory for the evaluation of the adequacy of the electric transmission system, since they are not completely symmetric. In this paper, we show how to perform the detailed calculation of the state variables of the FPF problem in an exact and symmetrical way, by means of solving multiple optimization problems. The procedure is illustrated using the IEEE 118 test system. (c) 2008 Elsevier B.V. All rights reserved.

关键词： Linear programming nonlinear programming Power flow Fuzzy models Optimization

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Optimal Deployment Control of Spinning Space Webs and Membranes

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2009年第5期32卷 1519-1530页

作者： Gardsback, Mattias Tibert, Gunnar Royal Inst Technol Dept Mech S-10044 Stockholm Sweden

Future solar sail and solar power satellite missions will consider using centrifugal forces for deployment and stabilization. Some of the main advantages with spin deployment are that the significant forces are in the plane of rotation, and a relatively simple control can be used and the tension in the membrane or web can be adjusted by the spin rate. Existing control strategies seem to either consume excessive energy or cause oscillations. In this study, control laws are derived from the solution to relevant optimal control problems and existing controls. The derived control laws are used in deployment simulations with both simple analytical three-degree-of-freedom models and a fully-three-dimensional finite element model. The results indicate that the derived control laws can be used to minimize the energy consumption and oscillations as for an optimal control, yet retain the simplicity of previous control laws.

关键词： Bang Bang Control Finite Element Analysis nonlinear programming Energy Consumption Elastic Modulus Solar Power Satellite Sequential Quadratic programming Electric Motors Solar Sail Linear Quadratic Regulator

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Optimization of Low-Thrust Reconfiguration Maneuvers for Spacecraft Flying in Formation

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2009年第5期32卷 1629-1638页

作者： Massari, Mauro Bernelli-Zazzera, Franco Politecn Milan Dipartimento Ingn Aerospaziale I-20156 Milan Italy

In this work, the problem of optimization of low-thrust reconfiguration maneuvers for spacecraft flying in formation is addressed. The problem is stated as the solution of an optimal control problem in which an objective function related to controls is minimized, satisfying a series of constraints on the trajectory that are both differential and algebraic. The problem has been faced by transcribing the differential constraints into a nonlinear programming problem with a parallel multiple-shooting method. The resulting problem has been solved with an interior point method. The method that has been developed is particularly suited for the solution of problems in which the trajectory is constrained with a great number of inequalities on both states and controls. The method has been applied to the design of reconfiguration maneuvers for spacecraft flying in formation;for which the collision avoidance issue leads to the imposition of a large number of inequalities on states derived from the minimum distance constraint.

关键词： Spacecrafts Thrust Trajectory Optimization nonlinear programming Satellite Formation Sequential Quadratic programming Direct Multiple Shooting Method Propellant Orbital Period Formation Flying

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nonlinear Robust Stochastic Control for Unmanned Aerial Vehicles

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2009年第4期32卷 1308-1319页

作者： Xu, Yunjun Univ Cent Florida Dept Mech Mat & Aerosp Engn Orlando FL 32816 USA

Almost all dynamical systems experience inherent uncertainties such as environmental disturbance, sensor noise, and modeling error due to approximations. In safety-critical applications, such as control of unmanned aerial vehicles, characterizing and controlling the statistical performance of the system become important tasks. This paper describes a new robust stochastic control methodology that is capable of controlling the statistical nature of state or output variables of a nonlinear system to desired (attainable) statistical properties (e.g., moments). First, as the online step, an asymptotically stable and robust output tracking controller is designed in which discontinuous functions are not involved. Second, as the offline step, undetermined control parameters in the closed-loop system are optimized through nonlinear programming. In this constrained optimization, the error between the desired and actual moments of state or output variables is minimized subject to constraints on statistical moments. As the key point to overcome the difficulties in solving the associated Fokker-Planck equation, a direct quadrature method of moments is proposed. In this approach, the state probability density function is expressed in terms of a finite collection of Dirac delta functions, with the associated weights and locations determined by moment equations. The advantages of the proposed method are 1) the ability to control any specified stationary moments of the states or output probability density function, 2) no need for the state process to be a Gaussian, and 3) robustness with respect to parametric and functional uncertainties. An unmanned aerial vehicle command-tracking control is used to demonstrate the capability of the proposed nonlinear stochastic control method and the results are successfully validated by Monte Carlo simulations.

关键词： Multiple Input Multiple Output UAV Sliding Mode Control nonlinear programming Stochastic Optimization Singular Perturbation Probability Density Functions nonlinear Systems Sensors Flight Path Angle

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