组合优化调度问题求解方法

1.引言优化是指一个从一组解中选取出最优解或最适应解的过程。优化方法涉及的工程领域很广,问题种类与性质繁多。归纳而言,最优化问题可分为函数优化问题和组合优化问题。其中函数优化的对象是一定区间内的连续变量,而组合优化的对象则是解空间中的离散状态。函数优化问题通常可描述为:令S为R~n上的有界子集(即变量的定义域),f:S→R为n维     

可行解优先蚁群算法对车辆路径问题的求解

针对车辆路径问题,给出了一种利用蚁群算法求解该问题的新方法。借鉴K-TSP问题的求解方法,优先构造可行解,通过对较优解路径上信息素的增强,最终得到问题的最优解或较优解。实验结果表明,用本方法求解车辆路径问题,简化了求解过程,缩短了求解时间,解决了无可行解的问题。     

就背包和部件加工问题浅论贪婪算法的运用及优化方案

贪婪算法作为一种求最优解问题的方法,具有简便、迅捷的特点,然而贪婪算法因其基于局部求最优解的特点,决定了其在很大程度上无法得到问题的最优解。本文通过对[0-1背包问题]以及部件加工问题的分析,阐述了贪婪算法的应用以及贪婪算法存在的局限性,进而引出贪婪算法的优化方案——k阶优化方法,进一步对求最优解问题进行完善和归纳。     

Job Shop 排序问题解空间定量分析

讨论Job shop排序问题不可行解的构造情况,给出了不可行解的一个充要条件以及2台机器n个加工工件的Job shop问题不可行解和可行解的计算公式,并由此得到一种概率模型的计算方法。通过计算发现,Job shop排序问题的不可行解所占比例非常大。     

Project Scheduling问题和Job—Shop问题的神经网络解

ＰｒｏｊｅｃｔＳｃｈｅｄｕｌｉｎｇ问题和Ｊｏｂ－Ｓｈｏｐ问题是著名的ＮＰ难题。本文用神经网络方法去解这两个问题，软件模拟结果是令人满意的。这种方法也为解一大类组合优化问题提供了一个新的途径。     

基于遗传算法求解TSP问题的一种算法

主要研究了用遗传算法求解TSP问题。阐述了简单遗传算法的设计方法、基本原理和基本步骤。描述了简单遗传算法在TSP问题中的应用现状。根据种群个体的多样性和分布情况,提出了判定遗传算法的截止代数。简单遗传算法具有易于陷入局部最优解、收敛速度慢的特点,针对这些特点,通过改进交叉算子,加入初始化启发信息,提高了遗传算法解的精度和收敛性。     

蚁群算法求解连续空间优化问题的一种方法

针对蚁群算法不太适合求解连续性优化问题的缺陷,提出用蚁群算法求解连续空间优化问题的一种方法.该方法将解空间划分成若干子域,在蚁群算法的每一次迭代中,首先根据信息量求出解所在的子域,然后在该子域内已有的解中确定解的具体值.以非线性规划问题为例所进行的计算结果表明,该方法比使用模拟退火算法、遗传算法具有更好的收敛速度.     

Fast Parallel Molecular Algorithm for Solving the Discrete Logarithm Problem over Group on Zp+ DNA-based Computing

加群Zp+上离散对数问题在公钥密码系统分析中具有非常广泛的应用.研究一种加群Zp+上离散对数问题的DNA计算算法.算法主要由解空间生成器、并行乘法器、并行加法器、解转换器及解搜索器组成.其中解空间生成器借鉴传统计算机中3表算法的思想,将解空间的生成分为3个部分来完成,极大减少了非法解的搜索空间.本算法的生物操作时间复杂度为O(k2),需要O(1)个试管数、O(2k)条DNA链,最长DNA链长为O(k2)(其中k为加群上离散对数问题群阶p的二进制编码位数).最后,通过DNA计算通用的试验方法对算法进行了仿真,验证了算法的可行性和有效性.     

路径交叉检测与消除方法和邻节点置换方法改进TSP的解

针对当前算法在求解规模较大的TSP时得到的近似解中常常存在路径交叉这一不足,提出了一种路径交叉检测与消除方法,可以完全消除路径交叉从而提高近似解的质量;通过分析近似解的结构,发现一些相邻节点相互交换位置也可以有效提高解的质量,因此提出了一种邻节点置换方法。实验表明提出的方法可以有效改进模拟退火算法求得的TSP近似解。     

基于可满足解空间的DNA算法--解决最小顶点覆盖问题

论文给出了基于可满足解空间的最小顶点覆盖问题的DNA算法,该算法直接生成可满足解空间,无须在全体解空间中进行各种过滤过程。在对图中的顶点进行适当的编码后,使用常规的生物操作完成可满足解空间的产生及最终解的分离。最后指出了该算法的优点、存在问题及下一步的研究方向。     

一种抑制EMD端点效应的改进方法

经验模式分解(EMD)存在的端点效应问题影响着该方法的应用。本文研究了基于端点优化对称延拓和镜像延拓的抑制EMD端点效应的改进方法,避免了单独采用端点优化对称延拓法在预测的点数较多时会造成速度较慢,以及单独采用镜像延拓法在处理端点不是极值点的短时间序列时效果不佳的问题。首先利用端点优化对称延拓法对数据序列两端各延拓一个局部极值,获取最佳的信号端点值,然后利用镜像延拓法把镜内的信号映射成一个不存在端点的环形信号,再进行经验模式分解。通过对仿真信号分析,表明该方法能够有效抑制端点效应问题。     

Development and evaluation of the problem identification picture cards method

In this paper the development and assessment of a new formative evaluation method called the problem identification picture cards (PIPC) method is described. This method enables young children to express both usability and fun problems while playing a computer game. The method combines the traditional thinking-aloud method with picture cards that children can place in a box to indicate that there is a certain type of problem. An experiment to assess this method shows that children may express more problems (verbally, or with a picture card, or with a combination of a picture card and a verbalisation) with the PIPC method than without this method (in which they can only indicate problems verbally). Children in the experiment did not just replace verbalisations by using the provided picture cards and some children preferred to use the PIPC method during the test instead of the standard thinking-aloud method. The PIPC method or some aspects of the method could be a good instrument to increase the amount of information expressed by young children during an evaluation.     

Vague集向Fuzzy集转化的一种新方法

提出Vague值向Fuzzy值转化的实用方法的定义。针对文献[6]中的一个Vague值向Fuzzy值转化的均值修正法,提出了加权均值修正法,并证明了这种方法同样是Vague值向Fuzzy转化的一种非常实用的方法。     

A Numerical Method for Free-Surface Flows and Its Application to Droplet Impact on a Thin Liquid Layer

We propose a simple and practical numerical method for free surface flows. The method is based various methods, the level set method of an interface capturing method, the THINC/WLIC (tangent of hyperbola for interface capturing/weighed line interface calculation) method of an interface tracking method, the CIP-CSL (constrained interpolation profile conservative semi-Lagrangian) method of a conservation equation solver, VSIAM3 (volume/surface integrated average based multi-moment method) of a fluid solver and the CSF (continuum surface force) model of a surface force model. The level set method and the THINC/WLIC method are combined by using a CLSVOF (coupled level set and volume-of-fluid) framework. The method is applied to Rayleigh-Taylor instability with surface tension force and droplet impact on a thin liquid layer (milk crown).     

Scaled Jacobian transpose based control for robotic manipulators

This paper presents a scaled Jacobian transpose based control method for robotic manipulators as a modification of a conventional Jacobian transpose based method. The proposed method has several advantages such as it shows faster convergence and better tracking performance than the conventional method, furthermore, it does not have any singularity problem similar to the conventional method. The scaled Jacobian transpose is obtained by collecting each pseudoinverse of the column vector of the Jacobian matrix. The proposed method performs a given task well under singular configurations while minimizing the task error. Finally, a few comparative studies with the conventional method are provided to show the effectiveness of the proposed method through simulations.     

A modified secant Newton method for non-linear problems

The paper describes a Modified Secant Newton method (MSN) which is derived from the variable metric method. The present procedure differs from the Secant Newton method (SN) in that in the MSN method the iterative displacement change involves only a scalar multiple of the usual unaccelerated change. Both the MSN method and the SN method are based on a Secant approach, but the MSN method leads to a reduction in the required number of iterations compared to the SN method. Two numerical examples involving elasto-plastic behaviour are presented.     

基于逆向Shear-Warp和边缘体素的快速重建算法

医学图像表面重建是协助医生对人体内部病变做出准确诊断的重要手段,而重建的速度直接影响医生的工作效率。为加快重建的速度,提出一种基于逆向Shear-Warp和边缘体素的快速重建算法。采取逆向Shear-Warp方法,减少了不必要的数据处理;通过在完全相反的两个方向上提取边缘体数据,得到全部的表面体素,重复利用这些体数据,而不必每次重新遍历整个数据场,提高了边缘体素的利用效率,达到了快速重建的目的。     

A Prefix Code Matching Parallel Load-Balancing Method for Solution-Adaptive Unstructured Finite Element Graphs on Distributed Memory Multicomputers

In this paper, we propose a prefix code matching parallel load-balancing method (PCMPLB) to efficiently deal with the load imbalance of solution-adaptive finite element application programs on distributed memory multicomputers. The main idea of the PCMPLB method is first to construct a prefix code tree for processors. Based on the prefix code tree, a schedule for performing load transfer among processors can be determined by concurrently and recursively dividing the tree into two subtrees and finding a maximum matching for processors in the two subtrees until the leaves of the prefix code tree are reached. We have implemented the PCMPLB method on an SP2 parallel machine and compared its performance with two load-balancing methods, the directed diffusion method and the multilevel diffusion method, and five mapping methods, the AE/ORB method, the AE/MC method, the MLkP method, the PARTY library method, and the JOSTLE-MS method. An unstructured finite element graph Truss was used as a test sample. During the execution, Truss was refined five times. Three criteria, the execution time of mapping/load-balancing methods, the execution time of an application program under different mapping/load-balancing methods, and the speedups achieved by mapping/load-balancing methods for an application program, are used for the performance evaluation. The experimental results show that (1) if a mapping method is used for the initial partitioning and this mapping method or a load-balancing method is used in each refinement, the execution time of an application program under a load-balancing method is less than that of the mapping method. (2) The execution time of an application program under the PCMPLB method is less than that of the directed diffusion method and the multilevel diffusion method.     

A high speed string correction method using a hierarchical file

This paper describes a high speed string correction method using a hierarchical file. After reviewing a string correction method based on the Levenshtein distance, a hierarchical file construction method is introduced. A multistage string correction method using this file is proposed. The lower bound of computational complexity is estimated, and it is shown that a multistage method using a special type of a hierarchical file can reduce computational labor greatly. The larger the number of strings considered is, the more efficient the method becomes. The results of computer simulations on 5374 phoneme sequences using two and three stage correction methods are stated. The condition for a multistage string correction method to obtain higher correction rates than an ordinary dictionary method is included.     

基于遗传算法的K均值聚类分析

1 前言聚类分析就是将数据对象分组成为多个类或簇,在同一个簇中的对象之间具有较高的相似度,而不同的簇中的对象差别较大。聚类分析目前应用广泛,已经成为数据挖掘主要的研究领域。通过聚类,人们能够识别密集的和稀疏的区域,从而发现数据的整体分布模式,还能找到数据间的有趣的相互关系。关于聚类分析目前已经有K均值,CURE等很多算法,