Ordinal Hill Climbing Algorithms for Discrete Manufacturing Process Design Optimization Problems

Thispaper introduces ordinal hill climbing algorithms for addressingdiscrete manufacturing process design optimization problems usingcomputer simulation models. Ordinal hill climbing algorithmscombine the search space reduction feature of ordinal optimizationwith the global search feature of generalized hill climbing algorithms.By iteratively applying the ordinal optimization strategy withinthe generalized hill climbing algorithm framework, the resultinghybrid algorithm can be applied to intractable discrete optimizationproblems. Computational results on an integrated blade rotormanufacturing process design problem are presented to illustratethe application of the ordinal hill climbing algorithm. The relationshipbetween ordinal hill climbing algorithms and genetic algorithmsis also discussed. This discussion provides a framework for howthe ordinal hill climbing algorithm fits into currently appliedalgorithms, as well as to introduce a bridge between the twoalgorithms.     

蚁群算法在求解旅行商问题中的应用综述

旅行商问题作为组合优化研究中最具挑战的问题之一, 自被提出以来就引起了学术界的广泛关注并提出了大量的方法来解决它. 蚁群算法是求解复杂组合优化问题的一种启发式仿生进化算法, 是求解旅行商问题的有效手段. 本文分别介绍蚁群算法中几个有代表性的算法, 综述了蚁群算法的改进、融合和应用的文献研究进展, 以评价近年来不同版本的蚁群算法为解决旅行商问题的发展和研究成果, 并针对改进蚁群算法结构框架、算法参数的设置及优化、信息素优化和混合算法等方面, 对现被提出的改进算法进行了分类综述. 对蚁群算法在未来对旅行商问题及其他不同领域的研究内容和研究热点的进一步发展提供了展望和依据.     

Two-stage updating pheromone for invariant ant colony optimization algorithm

Ant colony optimization (ACO) is a metaheuristic approach for combinatorial optimization problems. With the introduction of hypercube framework, invariance property of ACO algorithms draws more attention. In this paper, we propose a novel two-stage updating pheromone for invariant ant colony optimization (TSIACO) algorithm. Compared with standard ACO algorithms, TSIACO algorithm uses solution order other than solution itself as independent variable for quality function. In addition, the pheromone trail is updated with two stages: in one stage, the first r iterative optimal solutions are employed to enhance search capability, and in another stage, only optimal solution is used to accelerate the speed of convergence. And besides, the pheromone value is limited to an interval. We prove that TSIACO not only has the property of linear transformational invariance but also has translational invariance. We also prove that the pheromone trail can limit to the interval (0, 1]. Computational results on the traveling salesman problem show the effectiveness of TSIACO algorithm.     

求解TSP的改进模拟退火算法

利用模拟退火算法给出了求解旅行商问题的一种新方法.在模拟退火算法的基本原理基础上,针对解变换只交换两个城市而容易落入局部最优解的缺点,提出了在解变换产生新解的过程中,采用逆转操作的改进方法.这使得迭代过程突破局部最优圈,然后跳到另一个搜索空间.这样能够使其更具多样性,改善了模拟退火算法的局部搜索能力.并将其应用于求解旅行商问题,显著改善了它局部寻优的能力.在几个公共测试数据集上的结果表明,算法稳定可行,在求解组合优化问题方面,具有良好的性能.     

A two-dimensional mapping for the traveling salesman problem

The traveling salesman problem (TSP) is a classic problem in combinatorial optimization. An N-city asymmetric TSP has (N − 1)! tours. We develop a conceptual mapping of an N-city problem to a two-dimensional space and computer code for the defining function and its inverse. The transformation is implemented using color graphics and allows one to better understand the topography of the solution space and study the effects of different search techniques visually, leading to improvements in solution algorithms.     

A memetic algorithm with adaptive hill climbing strategy for dynamic optimization problems

Dynamic optimization problems challenge traditional evolutionary algorithms seriously since they, once converged, cannot adapt quickly to environmental changes. This paper investigates the application of memetic algorithms, a class of hybrid evolutionary algorithms, for dynamic optimization problems. An adaptive hill climbing method is proposed as the local search technique in the framework of memetic algorithms, which combines the features of greedy crossover-based hill climbing and steepest mutation-based hill climbing. In order to address the convergence problem, two diversity maintaining methods, called adaptive dual mapping and triggered random immigrants, respectively, are also introduced into the proposed memetic algorithm for dynamic optimization problems. Based on a series of dynamic problems generated from several stationary benchmark problems, experiments are carried out to investigate the performance of the proposed memetic algorithm in comparison with some peer evolutionary algorithms. The experimental results show the efficiency of the proposed memetic algorithm in dynamic environments.     

利用粒子群优化算法求解圆排列问题

针对已有算法搜索时间较长,且易于过早地收敛于非最优解的缺陷,利用粒子群优化算法给出了圆排列问题的求解方法.首先,在分析了圆排列问题与旅行商问题关系的基础上,将圆排列问题转化为旅行商问题,从而得到一个相应的组合优化问题.然后,利用粒子群优化算法进行了求解.接着,为了进一步提高算法的精度,文中给出了一种利用混合粒子群优化算法的方案.最后,在仿真实验中,与已有算法进行了比较,实验结果表明,文中所给方法是有效的.     

群体间竞争与协作的遗传算法解决旅行商问题

旅行商问题是经典的NP难组合优化问题之一,快速有效地解决旅行商问题具有重要的理论和实际意义。受自然界物种群体间相互联系的启发,提出了群体间竞争与协作的遗传算法来解决旅行商问题。该算法在迭代的过程中,每次只选择竞争力大的种群进行进化,同时为了维持各个种群间发展的平衡,对它们进行周期性的交流,能促使进化过程中中好的基因模式迅速地在各个种群中传播,提高了整体的进化速度。此算法不但能有效地维持群体的多样性,而且能提高收敛的速度。通过对旅行商问题的仿真实验,证明了该算法的可行性与有效性。     

一种求解旅行商问题的离散状态转移算法

本文提出了一种求解旅行商问题的离散状态转移算法,设计了交换、平移、对称等3种转移算子,讨论了算法的收敛性和时间复杂度等问题,研究了参数对算法的影响.实验结果表明,与模拟退火算法及蚁群算法等经典组合优化算法相比,该算法具有耗时短、寻优能力强等优点,这也表明了状态转移算法的适应性很好.     

基于小波精英解学习和多角度搜索的新型阴阳平衡优化算法

针对基本阴阳平衡优化算法计算精度低和优化速度慢等问题,提出一种新型阴阳平衡优化算法.首先,设计小波精英解学习策略,充分利用精英解的进化信息产生高质量的解,用于算法的全局勘探和局部开发;然后,将搜索角度引入解更新方程中,以实现对算法搜索空间的全方位搜索,并对所提出算法的收敛性进行理论分析;最后,采用连续优化测试函数和瓶颈旅行商问题进行数值实验,并将所提出算法与多种智能优化方法进行比较.实验结果表明,所提出算法具有更好的优化性能.     

多优解更新信息素的混合行为蚁群算法

蚁群算法在优化领域,尤其在组合优化问题中获得了较为成功的应用,然而它存在易于早熟收敛、搜索时间长等不足.针对该问题,提出了一种改进算法.该算法一方面在典型的状态转移规则中融合了一种随机选择策略,保证算法始终具有一定的探索能力;另一方面在搜索过程中保持一个优解池,通过交替使用池中最优解和其它次优解更新信息素,达到平衡算法强化搜索和分散搜索的目的.文中讨论了相关参数的选取方法,分析了所提算法的计算复杂度和收敛性,并针对典型的旅行商问题进行了仿真实验,结果表明该算法获得的解质量高于其他已有算法.     

离散萤火虫优化算法求解概率旅行商问题

对随机组合优化问题中的概率旅行商问题(PTSP)的理论和方法进行了研究分析,采用现代进化算法中有代表性发展优势的萤火虫优化算法(FA),提出一种离散萤火虫优化算法(DFA)以求解.其中引入了新的学习机制使其相比原始的萤火虫优化算法,更容易搜索到全局最优解,有更好的收敛性能.实验中用TSPLIB中的经典实例进行测试来验证其可行性.考察了萤火虫数量和进化迭代次数对求解结果性能的影响,并将DFA与GA、PSO和ACO等其他著名的进化计算算法进行性能比较.实验结果证实了DFA无论对固定访问概率,还是访问概率为区间内随机数等不同情况,都具有良好的有效性和高效性,因此对求解随机组合优化系列问题的有效解决具有一定参考和借鉴价值.     

求解旅行商问题的混合粒子群优化算法

结合遗传算法、蚁群算法和模拟退火算法的思想，提出用混合粒子群算法来求解著名的旅行商问题．与模拟退火算法、标准遗传算法进行比较，24种混合粒子群算法的效果都比较好，其中交叉策略D和变异策略F的混合粒子群算法的效果最好，而且简单有效．对于目前仍没有较好解法的组合优化问题，通过此算法修改很容易解决．     

蚁群算法及其在求解旅行商问题中的应用

蚁群算法是一种求解组合优化问题较好的方法。在蚁群算法的基本原理基础上,以旅行商问题为例,介绍了该算法求解TSP的数学模型及具体步骤,并通过仿真实验与粒子群优化算法等方法比较分析,表明了该算法在求解组合优化问题方面具有良好的性能。     

压缩搜索空间法解TSP

旅行商问题(TSP)是一个著名的组合优化问题,从TSP的区域特性入手,提出并详细描述了将搜索剪枝算法与遗传算法相结合的剪枝表法.在对中国旅行商问题(CTSF)的实验中,剪枝表法表现出了良好的寻优能力和鲁棒性,是一种新的可行解决方案.     

粒子群算法求解旅行商问题程序设计

粒子群优化算法是一种具备全局搜索能力的群集智能优化算法,针对一类离散的、NP完全的组合优化问题——旅行商问题,该文介绍了用粒子群算法求解旅行商问题的改进策略和主要模块的程序设计思想。将算法应用到20个城市的解旅行商问题所得到的结果与遗传算法进行比较,数字仿真与结果比较表明了改进粒子群算法求解该问题的有效性。     

Measuring instance difficulty for combinatorial optimization problems

Discovering the conditions under which an optimization algorithm or search heuristic will succeed or fail is critical for understanding the strengths and weaknesses of different algorithms, and for automated algorithm selection. Large scale experimental studies - studying the performance of a variety of optimization algorithms across a large collection of diverse problem instances - provide the resources to derive these conditions. Data mining techniques can be used to learn the relationships between the critical features of the instances and the performance of algorithms. This paper discusses how we can adequately characterize the features of a problem instance that have impact on difficulty in terms of algorithmic performance, and how such features can be defined and measured for various optimization problems. We provide a comprehensive survey of the research field with a focus on six combinatorial optimization problems: assignment, traveling salesman, and knapsack problems, bin-packing, graph coloring, and timetabling. For these problems - which are important abstractions of many real-world problems - we review hardness-revealing features as developed over decades of research, and we discuss the suitability of more problem-independent landscape metrics. We discuss how the features developed for one problem may be transferred to study related problems exhibiting similar structures.     

粒子群算法求解旅行商问题程序设计

粒子群优化算法是一种具备全局搜索能力的群集智能优化算法,针对一类离散的、NP完全的组合优化问题——旅行商问题．该文介绍了用粒子群算法求解旅行商问题的改进策略和主要模块的程序设计思想。将算法应用到20个城市的解旅行商问题所得到的结果与遗传算法进行比较,数字仿真与结果比较表明了改进粒子群算法求解该问题的有效性。     

A comparative study of the improvement of performance using a PSO modified by ACO applied to TSP

Swarm-inspired optimization has become very popular in recent years. Particle swarm optimization (PSO) and Ant colony optimization (ACO) algorithms have attracted the interest of researchers due to their simplicity, effectiveness and efficiency in solving complex optimization problems. Both ACO and PSO were successfully applied for solving the traveling salesman problem (TSP). Performance of the conventional PSO algorithm for small problems with moderate dimensions and search space is very satisfactory. As the search, space gets more complex, conventional approaches tend to offer poor solutions. This paper presents a novel approach by introducing a PSO, which is modified by the ACO algorithm to improve the performance. The new hybrid method (PSO–ACO) is validated using the TSP benchmarks and the empirical results considering the completion time and the best length, illustrate that the proposed method is efficient.     

MMAS-EC算法求解旅行商问题

针对蚁群算法在求解旅行商问题容易出现搜索精度不高的问题,提出一种结合排出算法的最大-最小蚁群系统算法（MMAS-EC）。算法采用全局寻优和局部搜索结合的策略,利用寻优效果较好的最大-最小蚁群系统指导全局搜索方向,同时引入排出算法来探索局部解空间,并采用2-opt操作减小了排出算法对初始位置的依赖,提高了解的稳定性。仿真实验表明：结合了排出算法的最大-最小蚁群系统算法与标准蚁群算法相比,在时间开销增加较小的情况下,取得了质量更高的解。