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EFFICIENCY OPTIMIZATION FOR SYSTEMS AND COMPONENTS IN MICROWAVE POWER ENGINEERING

JOURNAL OF MICROWAVE POWER AND ELECTROMAGNETIC ENERGY 2004年第1期39卷 15-29页

作者： Mechenova, V. A. Yakovlev, V. V. Worcester Polytech Inst Dept Math Sci Worcester MA 01609 USA Ferrite Co Inc Hudson NH USA

The paper is concerned with one aspect of optimization of microwave thermal processing, namely, with optimization of energy coupling interpreted as a numerical characteristic of system efficiency. Since in computer-aided design coupling can be evaluated through the computed reflections, an optimization scheme is presented that is particularly suitable for minimizing the reflection coefficient in typical systems and elements of microwave power engineering. Based on response surface methodology and the sequential quadratic programming for constrained optimization, the procedure is linked with the full-wave 3-D FDTD electromagnetic simulator QuickWave-3D. Credibility and effectiveness of the method is illustrated by four examples: dimensional optimization is performed for a dry waveguide load, a waveguide T-junction with a partial-height post, a water cylinder in a cavity, and a slotted waveguide-backed radiating element.

关键词： Design variables dry load efficiency energy coupling microwave heating modeling optimization quadratic approximation reflection coefficient response surface sequential quadratic programming slotted waveguide T-junction

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Mechanical assessment of time optimal robot motion

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COMPUTATIONAL MECHANICS 2004年第2期33卷 121-128页

作者： Giese, G Longman, RW Bock, HG Columbia Univ Dept Mech Engn New York NY 10027 USA Univ Heidelberg Inst Comp Sci D-6900 Heidelberg Germany

The use of time optimal path planning can speed up robots on assembly lines and allow them to run faster, increasing their productivity. This paper seeks to develop a more complete understanding of the nature of time-optimal point-to-point trajectories for polar coordinate robots and intends to show how effective direct numerical methods are in computing optimal control solutions, including the resolution of complicated motor switching structures. In time optimal robot point-to-point motion there is generically one robot axis that has the hardest time reaching its endpoint. And then, to whatever extent other axes have extra freedom, it must be used to help the axis with the hardest task, whenever possible. Such assistance makes use of different mechanical interaction forces and effects. In this paper we examine one basis type of robot, the polar coordinate robot, and analyze all types of forces during optimal motions, in order to develop an understanding of optimal maneuvers.

关键词： optimal robot control polar robot simulation numerical optimization sequential quadratic programming

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Multicriteria design optimization of a supersonic inlet based upon global missile performance

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JOURNAL OF PROPULSION AND POWER 2004年第3期20卷 542-558页

作者： Gaiddon, A Knight, DD Poloni, C Matra Bae Dynam Aerospatiale Alenia France F-92323 Chatillon France Rutgers State Univ Piscataway NJ 08854 USA Univ Trieste I-34127 Trieste Italy

The flight performance of a ramjet-powered missile is improved through the use of an automated optimization loop relying on computational-fluid-dynamics tools. A generic supersonic airbreathing missile is first described, and its performance is assessed for a representative mission using Reynolds-averaged Navier-Stokes computations for aerodynamics prediction and theoretical engine performance models. The loop links together an optimization algorithm with an aerodynamic software computing the aerodynamic balance of the missile. Several optimizations are performed using different global algorithms such as simplex, evolutionary strategies, or genetic algorithms. The first ones are mono-objective: for each point of the mission (acceleration, cruise, and maneuver), the best inlet shape has to be found. Then multiobjective optimizations are performed in order to find the pareto front, that is, the best set of shapes satisfying the whole mission.

关键词： Supersonic Airbreathing Missile Supersonic Inlets Aerodynamic Performance Aerodynamic Coefficients Ramjet Engines Mass Flow Rate Reynolds Averaged Navier Stokes Vector Evaluated Genetic Algorithm Fuel Consumption sequential quadratic programming

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Low-thrust minimum-fuel orbital transfer: A homotopic approach

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2004年第6期27卷 1046-1060页

作者： Haberkorn, T Martinon, P Gergaud, J CNRS IRIT ENSEEIHT UMR 5505 F-31071 Toulouse France

We describe in this paper the study of an Earth orbital transfer with a low-thrust (typically electro-ionic) propulsion system. The objective is the maximization of the final mass, which leads to a discontinuous control with a huge number of thrust arcs. The resolution method is based on single shooting, combined to a homotopic approach in order to cope with the problem of the initial guess, which is actually critical for nontrivial problems. An important aspect of this choice is that we make no assumptions on the control structure and in particular do not set the number of thrust arcs. This strategy allowed us to solve our problem (a transfer from low Earth orbit to geosynchronous equatorial orbit, for a spacecraft with mass of 1500 kg, either with or without a rendezvous) for thrusts as low as 0.1 N, which corresponds to a one-year transfer involving several hundreds of revolutions and thrust arcs. The numerical results obtained also revealed strong regularity in the optimal control structure, as well as some practically interesting empiric laws concerning the dependency of the final mass with respect to the transfer time and maximal thrust.

关键词： Orbital Transfer Thrust Pontryagin's Maximum Principle Geosynchronous Equatorial Orbit Earth Propulsion System Perigee Satellites Predictor Corrector Method sequential quadratic programming

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Solving mathematical programs with complementarity constraints as nonlinear programs

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OPTIMIZATION METHODS & SOFTWARE 2004年第1期19卷 15-40页

作者： Fletcher, R Leyffer, S Argonne Natl Lab Div Math & Comp Sci Argonne IL 60439 USA Univ Dundee Dept Math Dundee DD1 4HN Scotland

We consider solving mathematical programs with complementarity constraints (MPCCs) as nonlinear programs (NLPs) using standard NLP solvers. This approach is appealing because it allows existing off-the-shelf NLP solvers to tackle large instances of MPCCs. Numerical experience on MacMPEC, a large collection of MPCC test problems is presented. Our experience indicates that sequential quadratic programming (SQP) methods are very well suited for solving MPCCs and at present outperform interior-point solvers both in terms of speed and reliability. All NLP solvers also compare very favorably to special MPCC solvers on tests published in the literature.

关键词： MPCC complementarity constraints nonlinear programming sequential quadratic programming interior-point methods

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Design and deployment of a satellite constellation using collaborative optimization

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JOURNAL OF SPACECRAFT AND ROCKETS 2004年第6期41卷 956-963页

作者： Budianto, IA Olds, JR Georgia Inst Technol Sch Aerosp Engn Space Syst Design Lab Atlanta GA 30332 USA

A study of collaborative optimization as a systematic, multivariable, multidisciplinary method for the conceptual design of satellite constellations is presented. Collaborative optimization was selected because it is well suited to a team-oriented environment, such as often found in the constellation design process. The method provides extensive and formal exploration of the multidisciplinary design space and a scalable formulation of the problem without compromising its subsystems' flexibility or eliminating opportunities for collaboration. The feasibility and benefits of the collaborative optimization architecture are highlighted by the successful convergence of an application notional problem to design and deploy elements of a space-based infrared system that provides early missile warning. Furthermore, this study contributes to the existing knowledge of the collaborative optimization method by verifying the feasibility of nongradient optimization algorithms as both system and subsystem optimizers within the architecture. Finally, the demonstrated convergence of this problem, which involves integer variables, also demonstrates the flexibility of the architecture for handling mixed-discrete nonlinear multidisciplinary problems.

关键词： Satellite Constellations Constellations sequential quadratic programming Space Based Infrared System Launch Costs Spacecraft Design Earth STSS Missile Defense Agencies Computing Platform

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Rapid preliminary design of rectangular linear cellular alloys for maximum heat transfer

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AIAA JOURNAL 2004年第8期42卷 1652-1661页

作者： Kumar, RS McDowell, DL Georgia Inst Technol Atlanta GA 30332 USA

Design has traditionally involved selecting a suitable material for a given application. An understanding of structure-property relationships provides a more rigorous and scientific basis for choosing an appropriate material for a given set of performance requirements. Improved designs may be possible if the material microstructures could be tailored for application-specific performance requirement. Honeycombs, two-dimensional prismatic cellular metals extended in the third direction, are emerging as an important material system for multifunctional applications. A specific example of designing prismatic cellular microstructure of rectangular cell topology is considered for optimum heat transfer via forced convection through its cells. As opposed to most existing designs, which assume uniform cell structures a priori, grading the cell structure is considered to achieve optimal heat transfer performance. A two-dimensional finite element methodology is developed to model convective heat transfer through a rectangular cellular structure in an approximate yet efficient way, enabling rapid exploration of the design space for purposes of preliminary design. Novel features of the finite element methodology are that it models the void and convection heat transfer due to fluid flow through it in an implicit manner and that it employs sink terms in the energy equation to address heat transfer due to convection down the length of the cells, employing an isothermal upper bound solution strategy for each cell. The finite element approach is used in conjunction with optimization algorithms to design uniform and graded rectangular cell structures.

关键词： Dirichlet Boundary Condition Alloys Forced Convection Porous Materials Kinematic Viscosity sequential quadratic programming Finite Element Approximation Aspect Ratio Total Mass Flow Rate Thermal Performance

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Variable-fidelity aerodynamic optimization for turbulent flows using a discrete adjoint formulation

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AIAA JOURNAL 2004年第7期42卷 1281-1292页

作者： Le Moigne, A Qin, N Univ Sheffield Dept Mech Engn Sheffield S1 3JD S Yorkshire England

An aerodynamic shape optimization methodology based on a discrete adjoint solver for Navier-Stokes flows is described. The flow solver at the heart of this optimization process is a Reynolds-averaged Navier-Stokes code for multiblock structured grids. It uses Osher's approximate Riemann solver and the algebraic turbulence model of Baldwin-Lomax. A corresponding discrete Navier-Stokes adjoint solver is derived analytically. It has to calculate accurately the Jacobian, including the effect of the turbulence modeling. The shape deformations are parameterized by the use of a Bezier-Bernstein formulation. The optimization is gradient-based and employs the variable-fidelity optimization method of Alexandrov et al. that combines low- (Euler equations on a coarse grid) and high-fidelity (Navier-Stokes equations on a fine grid) models for better efficiency. The accuracy of the adjoint solver is verified through comparison with finite difference. An airfoil drag minimization problem and the three-dimensional Navier-Stokes optimization of the ONERA M6 wing are presented.

关键词： Three Dimensional Turbulent Flow Airfoil Aerodynamic Shape Optimization Baldwin Lomax Model Primitive Variable Baldwin Lomax Turbulence Model Navier Stokes Equations Reynolds Averaged Navier Stokes Eddy Viscosity sequential quadratic programming

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Optimal design of electronic components by mixed-integer nonlinear programming

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OPTIMIZATION AND ENGINEERING 2004年第3期5卷 271-294页

作者： Van De Braak, G Bünner, MJ Schittkowski, K Univ Bayreuth Dept Math D-95440 Bayreuth Germany Univ Munster Dept Math D-48149 Munster Germany EPCOS AG D-81617 Munich Germany

Cornputer-aided design optimization of electronic components is a powerful tool to reduce development costs on one hand and to improve the performance of (lie components on the other. In this paper, a mathematical model of an electronic filter is outlined. It depends oil certain parameters, some of then) of being continuous, others of integer type. The purpose of the paper is to introduce an extension of the well-known sequential quadratic programming (SQP) method to solve the mixed-integer programming problem (MINLP). It is assumed that the integer variables cannot be relaxed to real ones, that the integer range is sufficiently large, and that they possess some physical meaning so that they basically behave like continuous ones. The general idea is to combine all SQP step with a direct search cycle in the integer space, Hessian information is updated based on difference formulae at neighbored grid points. Numerical results are included to show the feasibility of the mixed-integer nonlinear programming code for academic test examples and in addition for the optimal design of an electronic filter.

关键词： electronic components mixed-integer nonlinear programming discrete optimization categorial variables sequential quadratic programming direct search method

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Optimization of shielded metal arc weld metal composition for charpy toughness

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WELDING JOURNAL 2004年第10期83卷 267S-276S页

作者： Murugananth, M Babu, SS David, SA Oak Ridge Natl Lab Div Met & Ceram Oak Ridge TN USA

Artificial neural network models that predict the Charpy-impact toughness values as a function of composition, heat treatment, and shielded metal arc welding process parameters were coupled with multipurpose optimization software. This coupled model was used to optimize the carbon, nickel, and manganese concentrations in a weld to achieve a maximum toughness of 120 J at -60degreesC. The coupled model used linear and nonlinear techniques to explore the possible combinations of carbon, manganese, and nickel concentrations for a given set of welding process parameters. An optimum weld metal composition was achieved only with nonlinear methods. The number of iterations and the exploration of input parameter space varied depending upon the type of nonlinear technique. The predicted weld metal composition was in agreement with published results.

关键词： Consumable Design Downhill Simplex Methods Genetic Algorithms Neural Network Modeling Nonlinear programming Optimization Methodologies sequential quadratic programming

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