一种基于构建基因库求解TSP问题的遗传算法

在分析了已有的求解TSP问题的优化算法后，提出了一种将建立基因库(Ge)与遗传算法结合起来的新算法(Ge_GA)。该算法的目的是用基因库指导整个种群的进化，其核心问题是基因库的建立及如何将基因库运用到遗传算法中。试验结果表明，基因库有效地提高了群体演化的质量，局部搜索与全局搜索的结合大大提高了算法收敛速度。对于每个测试的实例，其结果与最优解的误差都不超过0.001％。特别是对难于求解的TSP问题，如pcb442和n1577，都能够在理想的时间内找到最优解。     

一种基于基因库和多重搜索策略求解TSP的遗传算法

TSP是组合优化问题的典型代表，该文在分析了遗传算法的特点后，提出了一种新的遗传算法（GB_MGA），该算法将基因库和多重搜索策略结合起来，利用基因库指导单亲遗传演化的进化方向，在多重搜索策略的基础上利用改进的交叉算子又增强了遗传算法的全局搜索能力。通过对国际TSP库中多个实例的测试，结果表明：算法（GB_MGA）加快了遗传算法的收敛速度，也加强了算法的寻优能力。     

基于构建基因库求解TSP问题的改进遗传算法

文章针对TSP问题设计了一种将基因库和遗传算法结合起来的新算法,该算法首先构建一个基因库,在单亲演化中利用基因库指导种群的进化方向,其次在此基础上采用单亲进化遗传算法中的基因重组操作,保留每次获得的最好解组成初始种群,最后采用顺序交叉算子进行群体演化。给出的实验结果显示,该算法所获得的解与最优解的相对误差都不超过2%,该算法的收敛速度和寻优能力明显优于该问题的单亲进化遗传算法。     

一种基于基因库求解TSP的单亲遗传算法

研究商品流通路线问题,TSP是组合优化问题的典型代表。针对TSP问题提出了一种改进的遗传算法。以引入＂基因库＂为基础,为了寻找出最优路径,提出一种只使用变异算子和选择算子繁殖后代的单亲遗传算法（PGA）,并设计了一种新的组合算子作为算法的主搜索算子。算法利用基因库指导单亲遗传演化的进化方向,利用设计的组合算子来增强算法的搜索能力,从而很好地仿真了自然界的进化过程。计算结果证明,基因库的PGA算法具有较高的求解质量和求解效率,尤其是在求解Lin318 TSP问题时获得了优于目前最好解最短路径,可为设计提供有效的参考。     

基于分段混合蛙跳算法的旅行商问题求解

针对旅行商问题(TSP)在搜索后期解的多样性和精度下降的问题,提出一种解决TSP问题的分段混合蛙跳算法(S-SFLA)。该算法在搜索初期利用逆转变异算子减少交叉路径,在搜索的后期引入邻域搜索(个体邻域,局部最优领域,全局最优邻域)增加种群多样性。在整个搜索过程中记忆全局历史最优解与局部历史最优解,进行全局更新和局部更新,避免迂回搜索。在局部更新中,每一个青蛙都有机会得到更新。实验结果表明,与遗传算法、蚁群算法、基本蛙跳算法相比,S-SFLA算法在求解中等规模的TSP问题上具有更快的搜索速度和更高的求解精度。     

遗传算法的混合算子策略

在一般遗传算法中，求最优解时既可避免早熟收敛，又能提高收敛速度是困难的，因为算法中使用了单独一组交叉算子／变异算子。本文提出一种新的基于混合算子的遗传算法执行策略。在求解旅行商问题（TSP）中，为了提高局部搜索能力和收敛速度，给出了一种基于边重组的启发式交叉算子。仿真实验表明了这种算法的有效性。     

一种新的混合遗传算法求解旅行商问题

提出一种改进的混合遗传算法来求解TSP问题。在传统遗传算法基础上,杂交算子部分引入郭涛算法,使得算法保持较好的多样性和全局搜索能力,从而克服了传统遗传算法过早收敛的缺陷;变异算子引入粒子群算法,以加速算法收敛速度并提高求解精度,使其更快地找到最优解。通过TSPLIB大量经典实例验证,该算法均能快速找到比现有最优结果更好的解。     

求解旅行商问题的探索—开发—跳跃策略单亲遗传算法

针对遗传算法求解旅行商问题(TSP)时容易早熟、收敛速度慢等问题,提出一种基于探索—开发—跳跃策略的单亲遗传算法(EDJS-PGA)。该算法将基因移位、倒序、交换三种算子组合构成探索策略,用于扩展解的搜索空间,增强算法全局搜索能力;再将logistic混沌映射和改良圈操作融合为一种混沌映射改良圈算子,用于增强算法的局部搜索能力,构成开发策略;最后针对种群中的同优个体设计了近邻变异算子,构成跳跃策略,增强了算法跳出局部最优解的能力,使其兼具个体变异、局部优化、防止早熟等多重作用。通过对18个TSP实例进行仿真实验,结果表明EDJS-PGA相较于传统单亲遗传算法具有更高的求解精度和收敛速度,且最优解偏差率和平均误差率均处于较低水平;与其他文献对比,EDJS-PGA具有更强的鲁棒性和求解效率。     

融入遗传算法的混合蚁群算法

为了提高基本蚁群算法的收敛性能和全局求解能力,对基本蚁群算法进行了改进,提出了一类融入遗传算法的混合蚁群算法.在每代进化中保留最优解和次优解的公共解集后引入遗传操中的交叉算子和变异算子进行运算.对优秀解公共解集的保留加快了算法收敛速度,引入交叉和变异扩大了解的搜索空间,提高了解的全局性.通过对TSP问题的仿真运算表明,融入遗传算法的蚁群算法在收敛速度和解的全局性上都有较大的改善.     

基于基因库求解旅行商问题的遗传算法

针对传统遗传算法(genetic algorithm, GA)求解旅行商问题(traveling salesman problem, TSP)存在寻优效率低、实验结果缺乏一致性等问题，提出了一种基于基因库的遗传算法(genetic algorithm based on genes pool, GPGA)。GPGA从种群中搜索减小哈密顿圈长度的边，并当做优良基因构成基因库。父代哈密顿圈在基因库引导下产生更优的子代哈密顿圈，基因库也随着种群的不断进化而同步更新，引导种群个体逐步向最优解靠近。算例结果表明在同样条件下，GPGA比传统遗传算法和几种改进遗传算法的性能更优。     

A Neurogenetic approach for the resource-constrained project scheduling problem

A variety of metaheuristic approaches have emerged in recent years for solving the resource-constrained project scheduling problem (RCPSP), a well-known NP-hard problem in scheduling. In this paper, we propose a Neurogenetic approach which is a hybrid of genetic algorithms (GA) and neural-network (NN) approaches. In this hybrid approach the search process relies on GA iterations for global search and on NN iterations for local search. The GA and NN search iterations are interleaved in a manner that allows NN to pick the best solution thus far from the GA pool and perform an intensification search in the solution's local neighborhood. Similarly, good solutions obtained by NN search are included in the GA population for further search using the GA iterations. Although both GA and NN approaches, independently give good solutions, we found that the hybrid approach gives better solutions than either approach independently for the same number of shared iterations. We demonstrate the effectiveness of this approach empirically on the standard benchmark problems of size J30, J60, J90 and J120 from PSPLIB.     

A hybrid cuckoo search and genetic algorithm for reliability–redundancy allocation problems

Solving reliability and redundancy allocation problems via meta-heuristic algorithms has attracted increasing attention in recent years. In this study, a recently developed meta-heuristic optimization algorithm cuckoo search (CS) is hybridized with well-known genetic algorithm (GA) called CS–GA is proposed to solve the reliability and redundancy allocation problem. By embedding the genetic operators in standard CS, the balance between the exploration and exploitation ability further improved and more search space are observed during the algorithms’ performance. The computational results carried out on four classical reliability–redundancy allocation problems taken from the literature confirm the validity of the proposed algorithm. Experimental results are presented and compared with the best known solutions. The comparison results with other evolutionary optimization methods demonstrate that the proposed CS–GA algorithm proves to be extremely effective and efficient at locating optimal solutions.     

求解0-1背包问题的混合贪婪遗传算法

求解0-1背包问题（KP）的最优解的时候,传统遗传算法（GA）的局部求精能力不足而简单局部搜索算法的全局探索能力有限,针对上述问题,将这两个算法整合并提出了混合贪婪遗传算法（HGGA）。在GA全局搜索框架下增加局部搜索模块,并改进传统仅基于物品价值密度的修复算子,增加基于物品价值的贪婪混合选项,从而加速寻优过程。HGGA一方面引导种群在进化的优质解空间中展开精细搜索,另一方面依靠GA的经典操作算子开拓全局搜索空间,从而达到算法求精能力和开拓能力的良好平衡。HGGA分别在三组数据上做了测试,结果表明在第一组15个测试用例中的12个上,HGGA能够百分百找到最优解,成功率达到80%;在第二组小规模数据集上,HGGA的性能明显好于其他同类GA和其他元启发算法;在第三组大规模数据集上,HGGA较其他元启发式算法具有更好的稳定性和高效性。     

Genetic Algorithms for Project Management

The scheduling of tasks and the allocation of resource in medium to large-scale development projects is an extremely hard problem and is one of the principal challenges of project management due to its sheer complexity. As projects evolve any solutions, either optimal or near optimal, must be continuously scrutinized in order to adjust to changing conditions. Brute force exhaustive or branch-and-bound search methods cannot cope with the complexity inherent in finding satisfactory solutions to assist project managers. Most existing project management (PM) techniques, commercial PM tools, and research prototypes fall short in their computational capabilities and only provide passive project tracking and reporting aids. Project managers must make all major decisions based on their individual insights and experience, must build the project database to record such decisions and represent them as project nets, then use the tools to track progress, perform simple consistency checks, analyze the project net for critical paths, etc., and produce reports in various formats such as Gantt or Pert charts.Our research has developed a new technique based on genetic algorithms (GA) that automatically determines, using a programmable goal function, a near-optimal allocation of resources and resulting schedule that satisfies a given task structure and resource pool. We assumed that the estimated effort for each task is known a priori and can be obtained from any known estimation method such as COCOMO. Based on the results of these algorithms, the software manager will be able to assign tasks to staff in an optimal manner and predict the corresponding future status of the project, including an extensive analysis on the time-and-cost variations in the solution space. Our experiments utilized Wall's GALib as the search engine. The algorithms operated on a richer, refined version of project management networks derived from Chao's seminal work on GA-based Software Project Management Net (SPMnet). Generalizing the results of Chao's solution, the new GA algorithms can operate on much more complex scheduling networks involving multiple projects. They also can deal with more realistic programmatic and organizational assumptions. The results of the GA algorithm were evaluated using exhaustive search for five test cases. In these tests our GA showed strong scalability and simplicity. Its orthogonal genetic form and modularized heuristic functions are well suited for complex conditional optimization problems, of which project management is a typical example.     

基于遗传算法的混合蚁群算法

提出了一种新的求连续空间最优值的蚁群算法。结合遗传算法和蚁群算法各自的优点以及两种算法融合基础,提出了遗传算法融入到蚁群算法融合中的两种新策略,第一种策略是先利用遗传算法具有比较强的全局搜索能力,在大范围内寻找一组解,然后以此为基础,用蚁群算法快速寻找最优解X*best;另一种策略是利用遗传算法交叉操作产生蚁群算法中的新旅行路径,以此提高蚁群算法的全局搜索能力。用上述策略构造两个基于遗传算法的混合遗传算法。用测试函数Rosenbrock和测试函数Shubert验证了混合蚁群算法的正确性。     

一种基于相角映射的改进多目标粒子群优化算法

提出一种相角粒子群优化算法求解多目标优化问题。该算法采用相角映射实现了粒子在相角空间上仅依赖于归一化多目标函数的快速搜索,在粒子飞行信息共享机制上引入共享池概念,提出基于关联支配排序和相似度排序的共享池更新策略,提高了Pareto解的多样性。采用Sigma领导策略和混沌变异操作,平衡了算法的快速搜索能力和全局寻优能力。标准多目标测试函数和电力系统广域阻尼控制多目标优化算例表明了所提出算法的可行性和有效性。     

Evaluating performance advantages of grouping genetic algorithms

The genetic algorithm (GA) and a related procedure called the grouping genetic algorithm (GGA) are solution methodologies used to search for optimal solutions in constrained optimization problems. While the GA has been successfully applied to a range of problem types, the GGA was created specifically for problems involving the formation of groups. Falkenauer (JORBEL—Belg. J. Oper. Res. Stat. Comput. Sci. 33 (1992) 79), the originator of the GGA, and subsequent researchers have proposed reasons for expecting the GGA to perform more efficiently than the GA on grouping problems. Yet, there has been no research published to date which tests claims of GGA superiority. This paper describes empirical tests of the performance of GA and GGA in three domains which have substantial, practical importance, and which have been the subject of considerable academic research. Our purpose is not to determine which of these two approaches is better across an entire problem domain, but rather to begin to document practical differences between a standard off-the-shelf GA and a tailored GGA. Based on the level of solution quality desired, it may be the case that the additional time and resources required to design a tailored GGA may not be justified if the improvement in solution quality is only minor or non-existent.     

An exact schema theorem for adaptive genetic algorithm and its application to machine cell formation

This paper proposes an exact schema theorem that is able to predict the expected number of copies of schemas in the next GA generation. It focuses on two-point crossover, which is widely used in many GA applications. As two important GA control parameters, crossover probability (p_c) and mutation probability (p_m) affect the performance of GAs drastically. A set of good GA parameters help in improving the ability of a GA to search for near global optimal solutions. This work shows that optimal p_c and p_m do not exist in most cases. As a result, a compromised pair of p_c and p_m may help improve the performance of GA. A multiple population search strategy enabled fuzzy c-means based evolutionary approach, which embeds the proposed exact schema theorem, to machine cell formation is then proposed. The approach enables the crossover and mutation probabilities of GAs to be made adaptive to suit different stages of the search for near optimal solutions. Three case studies were conducted. The proposed approach was able to provide better solutions consistently.     

变焦遗传算法及其并行实现研究

遗传算法(Genetic Alogrithm,GA)以其简洁及适应性而获得广泛应用.通常遗传算 法由于串格式及串长的限制,搜索空间及分辨率是有限的,因而往往收敛于局部最优.文中 提出了适宜串、并行计算的变焦(Zooming)遗传算法及多任务并行策略,采用了解码因子、搜 索中心、快速变异等策略来解决搜索空间与分辨率的矛盾,并在工作站及transputer上分别 以串行、并行方式实现了变焦遗传算法.