We propose a feature enhanced image reconstruction method for spotlight mode synthetic aperture radar. Based on the image processing of Computerized tomography model, this method has increased resolution, reduced side...
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ISBN:
(纸本)1424411351
We propose a feature enhanced image reconstruction method for spotlight mode synthetic aperture radar. Based on the image processing of Computerized tomography model, this method has increased resolution, reduced side lobes and reduced speckle by incorporating prior information regarding the features of interested scattering fields. Also, by using the extensions of half quadratic regularization methods, this algorithm effectively deals with the complex valued, random phrase nature of the underlying SAR reflectivities.
Production planning and scheduling (PPS) in dynamic alliance is a complicated and difficult task as it has to be optimal and collaborative both for the individual enterprise and for the whole dynamic alliance network....
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ISBN:
(纸本)9781424415304
Production planning and scheduling (PPS) in dynamic alliance is a complicated and difficult task as it has to be optimal and collaborative both for the individual enterprise and for the whole dynamic alliance network. To acquire quicker response of production process in dynamic alliance environment, new requirements of PPS are analyzed, and the corresponding collaborative PPS model is established. Moreover, the enabling technologies such as the information exchange, coordination and conflict resolution mechanism and PPS optimization algorithm are discussed. The objective of this paper is to find a satisfactory solution and techniques for the optimization and collaboration of PPS system.
We designed a broadband quarter wave plate in the visible range using a twisted nematic liquid crystal film sandwiched between two compensation films. The quarter wave plate exhibits much wider bandwidth than the comm...
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We designed a broadband quarter wave plate in the visible range using a twisted nematic liquid crystal film sandwiched between two compensation films. The quarter wave plate exhibits much wider bandwidth than the commercial product, which is composed of a half wave plate and a quarter wave plate.
This paper describes the application of biologically-inspired algorithms and concepts to the design of wideband antenna arrays. In particular, we address two specific design problems. The first involves the design of ...
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ISBN:
(纸本)9780819466853
This paper describes the application of biologically-inspired algorithms and concepts to the design of wideband antenna arrays. In particular, we address two specific design problems. The first involves the design of a constrained-feed network for a Rotman-lens beamformer. We implemented two evolutionary optimization (EO) approaches, namely a simple genetic algorithm (SGA) and a competent genetic algorithm. We conducted simulations based on experimental data, which effectively demonstrate that the competent GA outperforms the SGA (i.e., finds a better design solution) as the objective function becomes less specific and more "general." The second design problem involves the implementation of polyomino-shaped subarrays for sidelobe suppression of large, wideband planar arrays. We use a modified screen-saver code to generate random polyomino filings. A separate code assigns array values to each element of the tiling (i.e., amplitude, phase, time delay, etc.) and computes the corresponding far-field radiation pattern. In order to conduct a statistical analysis of pattern characteristics vs. tiling geometry, we needed a way to measure the "similarity" between two arbitrary filings to ensure that our sampling of the tiling space was somewhat uniformly distributed We ultimately borrowed a concept from neural network theory, which we refer to as the "dot-product metric," to effectively categorize filings based on their degree of similarity.
The problems related to practical realization (as a computer program) of difference schemes of the solution of diffusion equations that describe pollutants transport in the river water are considered in this paper. In...
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The problems related to practical realization (as a computer program) of difference schemes of the solution of diffusion equations that describe pollutants transport in the river water are considered in this paper. In particular, the problems of optimum choosing of the algorithm parameters on which depend the accuracy, the time and the possibility of practical realization of the equation solution are considered. The demand to reduce as much as possible the time and the errors of calculations, and also the simplicity of the functions of certain classes used in mathematical models and their maximum accordance to real physical conditions are considered as criteria of optimality. (c) 2006 Elsevier Inc. All rights reserved.
An optimization strategy for high speed machining of hardened die/mold steel based on machining feature analysis was studied. It is a further extension of the previously presented study on the thermal mechanism of end...
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An optimization strategy for high speed machining of hardened die/mold steel based on machining feature analysis was studied. It is a further extension of the previously presented study on the thermal mechanism of end milling and constant cutting force control. An objective function concerning machining cost and associated optimization algorithm based on machining time and cutting length calculation was proposed. Constraints to satisfy specific machining strategies when high speed machining the hardened die/mold steel, trochoid tool path pattern in slot end milling to avoid over-heat and feed rate adaptation to avoid over-load, were also discussed. As a case study, the tool selection problem when machining a die part with multiple machining features was investigated.
A new artificial immune algorithm （AIA） simulating the biological immune network system with selfadjustment function is proposed in this paper. AIA is based on the modified immune network model in which two methods ...
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A new artificial immune algorithm （AIA） simulating the biological immune network system with selfadjustment function is proposed in this paper. AIA is based on the modified immune network model in which two methods of affinity measure evaluated are used, controlling the antibody diversity and the speed of convergence separately. The model proposed focuses on a systemic view of the immune system and takes into account cell-cell interactions denoted by antibody affinity. The antibody concentration defined in the immune network model is responsible directly for its activity in the immune system. The model introduces not only a term describing the network dynamics, but also proposes an independent term to simulate the dynamics of the antigen population. The antibodies＇ evolutionary processes are controlled in the algorithms by utilizing the basic properties of the immune network. Computational amount and effect is a pair of contradictions. In terms of this problem, the AIA regulating the parameters easily attains a compromise between them. At the same time, AIA can prevent premature convergence at the cost of a heavy computational amount （the iterative times）. Simulation illustrates that AIA is adapted to solve optimization problems, emphasizing muhimodal optimization.
Design optimization using high-fidelity computational fluid dynamics simulations is becoming increasingly popular, sustaining the desire to make these methods more computationally efficient. A reduction in problem dim...
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Design optimization using high-fidelity computational fluid dynamics simulations is becoming increasingly popular, sustaining the desire to make these methods more computationally efficient. A reduction in problem dimensions as a result of improved parameterization techniques is a common contributor to this efficiency. The focus of this paper is on the high-fidelity aerodynamic design of airfoil shapes. A multifidelity design search method is presented which uses a parameterization of the airfoil pressure distribution followed by inverse design, giving a reduction in the number of design variables used in optimization. Although an expensive analysis code is used in evaluating airfoil performance, computational cost is reduced by using a low-fidelity code in the inverse design process. This method is run side by side with a method which is considered to be a current benchmark in design optimization. The two methods are described in detail, and their relative performance is compared and discussed. The newly presented method is found to converge towards the optimum design significantly more quickly than the benchmark method, providing designs with greater performance for a given computational expense.
A hybrid trajectory optimization procedure for a class of solar-electric-propulsion, gravity-assist, outer-planet missions is presented. The parameter space of a target mission is often nonconvex and a calculus-of-var...
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A hybrid trajectory optimization procedure for a class of solar-electric-propulsion, gravity-assist, outer-planet missions is presented. The parameter space of a target mission is often nonconvex and a calculus-of-variations-based optimization algorithm suffers difficulties efficiently exploring this space. A hybrid procedure using a genetic algorithm to drive a calculus-of-variations program is developed to automate searching over a reduced parameter space. Employing the hybrid procedure, the delivered mass profiles of a Uranus and Pluto mission are generated more quickly than by using the calculus-of-variations optimization algorithm alone.
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