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gradient-based optimization method for producing a contoured beam with single-fed reflector antenna

Journal of Systems Engineering and Electronics 2019年第1期30卷 22-29页

作者： LIAN Peiyuan WANG Congsi XIANG Binbin SHI Yu XUE Song School of Mechano-Electronic Engineering Xidian University Xinjiang Astronomical Observation Chinese Academy of Sciences Department of Mechanical Engineering Thornton Science Park University of Chester

A gradient-based optimization method for producing a contoured beam by using a single-fed reflector antenna is presented. First, a quick and accurate pattern approximation formula based on physical optics(PO) is adopted to calculate the gradients of the directivity with respect to reflector's nodal displacements. Because the approximation formula is a linear function of nodal displacements, the gradient can be easily derived. Then, the method of the steepest descent is adopted, and an optimization iteration procedure is proposed. The iteration procedure includes two loops: an inner loop and an outer loop. In the inner loop, the gradient and pattern are calculated by matrix operation, which is very fast by using the pre-calculated data in the outer loop. In the outer loop, the ideal terms used in the inner loop to calculate the gradient and pattern are updated, and the real pattern is calculated by the PO method. Due to the high approximation accuracy, when the outer loop is performed once, the inner loop can be performed many times, which will save much time because the integration is replaced by matrix operation. In the end, a contoured beam covering the continental United States(CONUS) is designed, and simulation results show the effectiveness of the proposed algorithm.

关键词： reflector antennas single feed contoured beam gradient-based optimization method.

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gradient-based Kriging approximate model and its application research to optimization design

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Science China(Technological Sciences) 2009年第4期52卷 1117-1124页

作者： XUAN Ying XIANG JunHua ZHANG WeiHua ZHANG YuLin College of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China

In the process of multidisciplinary design optimization, there exits the calculation complexity problem due to frequently calling high fidelity system analysis models. The high fidelity system analysis models can be surrogated by approximate models. The sensitivity analysis and numerical noise filtering can be done easily by coupling approximate models to optimization. Approximate models can reduce the number of executions of the problem's simulation code during optimization, so the solution efficiency of the multidisciplinary design optimization problem can be improved. Most optimization methods are based on gradient. The gradients of the objective and constrain functions are gained easily. The gra- dient-based Kriging (GBK) approximate model can be constructed by using system response value and its gradients. The gradients can greatly improve prediction precision of system response. The hybrid optimization method is constructed by coupling GBK approximate models to gradient-based optimiza- tion methods. An aircraft aerodynamics shape optimization design example indicates that the methods of this paper can achieve good feasibility and validity.

关键词： Kriging approximation function gradient-based approximate model hybrid optimization method multidisciplinary design optimization

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Adaptive gradient-based and Anisotropic Diffusion Equation Filtering Algorithm for Microscopic Image Preprocessing

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Journal of Signal and Information Processing 2013年第1期4卷 82-87页

作者： Hailing Liu Jingling Institute of Technology College of Information Technology Nanjing China

In image acquisition process, the quality of microscopic images will be degraded by electrical noise, quantizing noise, light illumination etc. Hence, image preprocessing is necessary and important to improve the quality. The background noise and pulse noise are two common types of noise existing in microscopic images. In this paper, a gradient-based anisotropic filtering algorithm was proposed, which can filter out the background noise while preserve object boundary effectively. The filtering performance was evaluated by comparing that with some other filtering algorithms.

关键词： Microscopic Image Image Preprocessing Anisotropic gradient-based

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