二维电阻抗断层成像算法研究

粒子群算法是一种随机、智能、全局优化算法,近年来越来越多的被应用于电磁学领域。提出修正的粒子群算法,并应用其进行电阻抗断层成像研究。对研究的圆形求解域采用有限元法进行剖分,电流注入采用三角电流法,并用修正的粒子群算法对园域内电导率目标进行介质重构。数值仿真结果表明:该方法对求解域内的目标位置定位准确,并能够准确地反映场域内电导率的分布。     

A heuristic method for solving triangle packing problem

INTRODUCTION Most packing problems (Dowsland and Dow-sland, 1992) are NP-hard (Garey and Johnson, 1979); among which are bin-packing, floorplan, rectangle packing, packing a set of circles into a large circle or square, non-rectangular packing problems and so on (Li and Milenkovic, 1995; Liang et al., 2002; Lip-nitskii, 2002; Milenkovic and Daniels, 1996; Milenk-ovic et al., 1991; Osogami and Okano, 2003; Wang, 2002). Some of these such as bin-packing problem and rectangle packing p…     

包装问题的演化算法

文章设计了一个求解包装问题的演化算法,在演化算法中采用了行之有效的个体编码方案、选择策略、杂交算子及变异算子,并通过实验进行算法性能的验证和分析。实验结果表明,该算法能够在很短的时间内找到包装问题的近似最优解。     

光线追踪中射线与多边形求交的一种算法及实现

本文给出了在光线追踪中射线与多边形求交的一种算法;此方法先判断,后求交、     

模拟退火算法在优化中的研究进展

模拟退火算法在处理全局优化、离散变量优化等困难问题中,具有传统优化算法无可比拟的优势.在计算机计算速度不断提高的条件下,具有不可低估的发展潜力和重要的研究价值.本文研究分析了基本的模拟退火算法原理,主要介绍了模拟退火算法的发展历史和特点,综合了近期关于模拟退火算法研究进展.本文在比较了模拟退火算法与传统的优化方法的基础上,最后指出了它的发展趋势和研究热点,对模拟退火算法在优化中的推广应用具有重要意义.     

SA法在求解非线性约束优化问题中的应用

传统数学规划方法如梯度法等在解决非线性规划问题时,往往会由于问题本身的多峰性而落入局部最优解中,得不到全局最优解,这使得传统方法在解决非线性规划问题中受到很大的限制.80年代初,S.Kirkpatrick提出了模拟退火算法(Simutaneous Annealing),该方法在解决复杂的组合优化问题中可以得出很好的结果.它是一种仿金属退火物理过程的随机算法,在理想状态下可得出全局最优解,并能以一定的概率跳出局部最优解所在的区域.本文我们将探讨SA法在求解非线性约束优化问题中的应用.     

条形装箱问题的基于后缀表达式的混合遗传算法

装箱问题作为一种常见的运筹问题,在很多领域有着重要的应用,装箱问题可以分为一维、二维和三维装箱.主要讨论了二维装箱中条形装箱问题的遗传算法的求解,其中采用后缀表达式的形式对装箱方案进行编码,并详细提出了解码的算法和有关的证明,最后通过实例证明了该算法是可行的.     

Ant-cycle based on Metropolis rules for the traveling salesman problem

In this paper, recent developments of some heuristic algorithms were discussed. The focus was laid on the improvements of ant-cycle （AC） algorithm based on the analysis of the performances of simulated annealing （SA） and AC for the traveling salesman problem （TSP）. The Metropolis rules in SA were applied to AC and turned out an improved AC. The computational results obtained from the case study indicated that the improved AC algorithm has advantages over the sheer SA or unmixed AC.     

An efficient hybrid evolutionary optimization algorithm based on PSO and SA for clustering

The K-means algorithm is one of the most popular techniques in clustering. Nevertheless, the performance of the K- means algorithm depends highly on initial cluster centers and converges to local minima. This paper proposes a hybrid evolutionary programming based clustering algorithm, called PSO-SA, by combining particle swarm optimization （PSO） and simulated annealing （SA）. The basic idea is to search around the global solution by SA and to increase the information exchange among particles using a mutation operator to escape local optima. Three datasets, Iris, Wisconsin Breast Cancer, and Ripley＇s Glass, have been considered to show the effectiveness of the proposed clustering algorithm in providing optimal clusters. The simulation results show that the PSO-SA clustering algorithm not only has a better response but also converges more quickly than the K-means, PSO, and SA algorithms.     

Distribution Network Reconfiguration Based on ESA

本文提出了一种新的用于配电网络重构的优化方法－进化策略退火（ＥＳＡ）法,该方法将模拟进化策略法（ＥＳ）与模拟退火法（ＳＡ）进行了有机结合．首先用ＥＳ法选择ＳＡ法的初始温度,然后用改进ＳＡ法搜索重构的全局最优解．为加快寻优速度,本文提出了一种启发式规则用于降温策略,并采用了有效的潮流算法．仿真结果表明了ＥＳＡ法的有效性     

一种基于评价函数的三维矩形布局遗传算法

针对三维矩形布局问题,提出一种基于评价函数的布局遗传算法.该算法根据布局已知条件建立定序和定位评价函数,然后通过对评价函数值的比较确定布局的定序和定位规则;最后采用遗传算法优化定序和定位规则的参数.算例测试结果表明,该算法具有良好的计算效果.     

矩形布局的启发式优化策略

利用可行域算法求解矩形布局问题,通过调整矩形布入形态,改变其单一的可行域形式增大其解空间。算例结果表明,矩形调整对布局结果影响有规律,利用可行域算法求解矩形布局问题,简便、快捷、灵活、适应性强,从而能够灵活快速地获得更优异的矩形布局排布方案指导工程实践。     

非球形粒子的检测与识别

激光相位多普勒技术 (PDA)是目前公认有效的多参数粒子测量技术之一 ,但是PDA对粒子的非球形特性极为敏感 .本文分析了粒子的非球形特性对PDA的影响 ,明确了PDA信号参数与粒子非球形特性的关系 ,表明非球形粒子条件下的PDA信号相位差是理想粒子条件下PDA信号相位差的无偏估计 .提出了基于对象分类识别的非球形粒子的检测方法 ,利用模糊模式识别中的群体识别技术 ,计算对象特性与参照物特性的贴近度 ,根据择近原则判断对象的类别及数量 .实验表明 ,不规则粒子的统计分类及其识别具有实用价值     

一种改进不规则采样信号频谱分辨率的算法

不规则采样信号的谱估计是时间序列分析中的一个重要问题。为改进不规则采样信号谱估计的分辨率,提出了一种抑制非均匀离散傅里叶变换频谱泄漏的算法,通过迭代非线性估计实现不规则采样信号离散傅里叶变换的计算。实际计算试验结果显示,这种方法能有效地抑制非均匀离散傅里叶变换结果中的频谱泄漏,提高DFT频谱的分辨率。     

A new fast algorithm for computing the distance between two disjoint convex polygons based on Voronoi diagram

INTRODUCTION To compute the minimum distance between two convex polygons or polyhedrons is often a main step of many applications, such as collision detection (Choi et al., 2006; Li et al., 2003), path planning. In order to reduce the time complexity of the algorithm as much as possible, the convex property must be applied fully. Edelsbrunner (1985) proposed an algorithm for computing the minimum distance between two dis- joint convex polygons. The algorithm takes O(logm logn) time, and …     

A new algorithm for computing the convex hull of a planar point set

When the edges of a convex polygon are traversed along one direction,the interior of the convex polygon is always on the same side of the edges. Based on this characteristic of convex polygons,a new algorithm for computing the convex hull of a simple polygon is proposed in this paper,which is then extended to a new algorithm for computing the convex hull of a planar point set. First,the extreme points of the planar point set are found,and the subsets of point candidate for vertex of the convex hull between extreme points are obtained. Then,the ordered convex hull point sequences between extreme points are constructed separately and concatenated by removing redundant extreme points to get the convex hull. The time complexity of the new planar convex hull algorithm is O(nlogh) ,which is equal to the time complexity of the best output-sensitive planar convex hull algorithms. Compared with the algorithm having the same complexity,the new algorithm is much faster.     

模拟退火改进粒子群优化算法求解优化问题

针对粒子群优化算法后期易陷于局部最小的缺点,引入模拟退火思想,建立模拟退火—粒子群优化算法。通过求解函数优化问题对比实验,表明改进后的粒子群优化算法增强全局寻优能力,搜索成功率大为提高。     

关于平面多边形有向面积的一些定理

本文给出多边形有向面积的一个定值定理和多边形中线三角形的一些性质,把文［２］定理４和三角形中线定理等结论推广到更一般的情形。同时还给出了多边形有向面积公式的初等证明。我们约定,本文所指的多边形是指边不自交的平面多边形     

布局约束及模型的研究

在研究现有布局问题的基础上,对布局问题中的各种约束进行了研究和归类,并分析了它们在布局模型中所起的作用;利用面向对象思想给出了布局约束的表达形式;采用自上而下的分层设计思想,提出了布局问题的复合知识模型,为今后的布局设计提供了参考。     

STOCHASTIC INTERPOLATION METHODFOR FRACTAL MODELS

ＳＴＯＣＨＡＳＴＩＣＩＮＴＥＲＰＯＬＡＴＩＯＮＭＥＴＨＯＤＦＯＲＦＲＡＣＴＡＬＭＯＤＥＬＳＺｈａｏＬｉｎｄｕ（赵林度）ＳｈｅｎｇＺｈａｏｈａｎ（盛昭瀚）（ＳｃｈｏｏｌｏｆＥｃｏｎｏｍｉｃｓａｎｄＭａｎａｇｅｍｅｎｔ）ＳＴＯＣＨＡＳＴＩＣＩＮＴＥＲＰＯ...