共查询到18条相似文献,搜索用时 150 毫秒
1.
遗传算法的基因定位算子 总被引:2,自引:0,他引:2
针对遗传算法局部搜索能力弱,求解精度不高的缺陷提出了一个基因定位算子.该算子的思路是进化一定代数(L)后通过对最优的若干个(N)染色体基因位从高位到低位逐次进行比较,如果当前的基因位都相同时便把该基因位确定下来,以后的交叉、变异操作都不让该基因位参考,随着算法的进行,染色体基因便从高位到底位逐渐地确定下来.基次,通过在基因定位过程中引入模拟退火思想和小生境技术等局部搜索能力的算法,提高该算子的全局优化能力.最后,通过几个非常容易陷入局部最优的测试函数测试表明几乎所有的峰值都得到了理论值. 相似文献
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针对遗传算法的早熟现象、模式欺骗和局部搜索能力弱等缺陷提出了一个协同进化计算模型.该模型在基本遗传算法基础上引入多种群协同进化,利用性别特征改进交叉算子,采用小生境技术保持多样性.通过将问题求解转变为有向图遍历提出了染色体基因定位算子,使得问题求解和染色体中基因定位结合起来,提高问题求解的质量.在定位过程中可以和模拟退火等局部搜索能力强的启发搜索算法结合.通过几个非常容易陷入局部最优的测试函数和多峰函数测试,表明几乎所有的峰值都得到了理论值. 相似文献
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为了避免遗传算法在求解数值优化问题时出现搜索能力差、多样性缺失等弊端,提出一种基于实数编码的改进遗传算法(IRCGA).算法集成两个特别设计的算子:模拟二进制跳跃基因算子(SBJG)和多方向交叉算子(MX).SBJG算子以染色体为操作对象,本质上模拟了二进制跳跃基因操作中的插入运动,即利用一种随机的方式将选定的染色体块插入到染色体位点,实现种群内部染色体间的转位,为种群提供额外的遗传多样性;MX算子通过增加交叉方向的方式扩大算子的搜索区域,从而提升后代个体质量与算法的搜索能力.在11个实例的基础上进行对比实验,结果表明,采用改进算子能够明显提升算法在求解数值优化问题时的性能,同时,相比于其他先进有效的算法,IRCGA具有较强的搜索能力且能够维持一定的种群多样性,从而验证了改进算法的有效性和可行性. 相似文献
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郭涛算法可能是目前求解TSP问题最快的演化算法,其算法的核心在于Inver-over算子的设计,但在城市规模超过80时,该算子寻找全局最优解的能力就会下降。将原Inver-over算子的线性逆转改为环形逆转,改进逆转方式后,被逆转的基因片段可以包括整个染色体,这样能有效地防止解的早熟。同时,在原算法的基础上,引入了映射模块,能使父代中好的基因片段得到遗传,使好的基因片段能让更多的染色体所享有,不会因为父代被替代而让好的基因模式丢失。实验表明:改进后的算法增强了原Inver-over算子对最优解的搜索能力,并且对TSPLIB中大部分实例均可搜索到最优解。 相似文献
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为了解决情感特征选择问题,提出了一种改进的遗传算法。该算法利用从基因和个体两个方面设计的种群多样性算子产生较好的初始种群分布,随着遗传算子将群体中的个体吸引到局部最优点附近时,调用禁忌搜索算法(TS)对群体中各个个体进行局部搜索。仿真试验结果表明,该算法拓展了搜索空间,有效地防止了早熟现象的出现,能够得到令人满意的最优特征子集。 相似文献
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遗传算法具有良好的全局搜索能力,但有过早收敛和过慢结束的缺点。K-Means算法具有很强的局部搜索能力,但算法有对初始聚类中心敏感而易陷入局部最优解。针对上述问题,提出了基于K-Means变异算子的混合遗传算法聚类,将K-Means算法的局部搜索能力与遗传算法的全局寻优搜索能力相结合,在遗传算法中引入K-Means变异算子,采用符号编码、自适应变异、最优个体保留策略的混合遗传算法。仿真实验表明,该算法有效克服了遗传算法过慢收敛和K-Means算法陷入局部收敛的问题,从而得到更好的聚类效果。 相似文献
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改进量子遗传算法及其应用 总被引:6,自引:1,他引:5
针对量子遗传算法在多维复杂函数优化中迭代次数多、易陷入局部极值等缺点,提出新的量子遗传算法。通过搜索各种群中各染色体的最优个体,组成一个新的种群,并以此种群作为当前最优种群来确定量子门的全局最优搜索方向。引入小生境协同进化策略初始化量子种群,使量子染色体均匀分布于初值空间。以非线性连续优化问题为例所进行的仿真结果表明,该方法具有收敛速度快、寻优能力强等优点。最后,将该算法应用于化工过程的优化,取得良好的效果。 相似文献
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针对一维下料优化问题,提出了基于蜂群遗传算法的优化求解方案.具体做法是,以实数表示的各零件长度的一个排列作为一个染色体,其中每个零件的长度作为基因;根据自然界蜂群生物学原理设置了两个种群,一个种群主要用于全局搜索,另一个种群主要用于局部搜索;采用最优个体交叉策略;遗传算子包括联赛选择算子,顺序交叉算子,2-交换变异算子和抑制算子.仿真实验结果表明,该算法逼近理论最优值,而且收敛速度快,较好地解决了一维下料问题. 相似文献
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针对免疫克隆遗传算法存在着"早熟"和局部搜索能力弱的问题,提出了一种改进方法.该方法用一位修正算子来改进后期局部搜索方面的不足,并对免疫克隆遗传算法的各个算子进行了改进.实验表明,新的改进算法在搜索效率和搜索能力上都有着显著的提高. 相似文献
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基于子句权重学习的求解SAT问题的遗传算法 总被引:7,自引:1,他引:7
该文提出了一种求解SAT问题的改进遗传算法(SAT—WAGA).SAT-WAGA算法有多个改进性特点:将SAT问题的结构信息量化为子句权重,增加了学习算子和判定早熟参数,学习算子能根据求解过程中的动态信息对子句权重进行调整,以便防止遗传进程的早熟,同时,算法还采用了最优染色体保存策略,防止进化过程的发散.该文最后描述了实现包括SAT—WAGA等多个算法的实验系统,对选择最佳早熟判定参数值给出了一些有效的建议.实验结果表明:与一般遗传算法相比,SAT—WAGA算法在求解速度、成功率和求解问题的规模等方面都有明显的改善. 相似文献
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A Novel Genetic Algorithm and its Application in Fuzzy Variable Structure Control of Fuel Cell 总被引:1,自引:0,他引:1
Xing-Jin Sun Guang-Yi Cao Xin-Jian Zhu 《Journal of Intelligent and Robotic Systems》2001,31(1-3):299-316
A novel genetic algorithm (GA) is proposed; a ranking genetic algorithm with improved crossover operator. The whole colony is divided into several sub-colonies, and each sub-colony is called a family, which is represented by its best individual. This algorithm includes two levels of structure: the family level and the harmonizing level. The families are parallel during the process of evolution. The harmonizing level ranks all families based on their fitness values, and transports the best individual of the first-rank family to low-grade families so as to accelerate their evolution. Two levels of competition are constructed; one among individuals of a family, and the other among families. The competition within a family is accomplished by a genetic algorithm with improved crossover operator. A family's mutation probability is determined by its relative competitive power. In this way, a rapid and global convergence to the optimum goal is obtained. The GA crossover operator is improved for the case of floating point operations. The improved crossover operator can generate child individuals at random within the space of the supercube, which enhances the space searching rate and precision. Finally, the proposed novel GA is applied to the fuzzy-variable structure control (FVSC) system of a molten carbonate fuel cell (MCFC). The simulation results are satisfying. 相似文献
14.
总结单纯形搜索算法的核心思想.然后提出单纯形交叉方向算子和最优小生境、次差小生境与最差小生境3个概念.在最优小生境中采用单纯形搜索算法得到局部极值,在最优小生境与次差小生境之间用单纯形交叉方向算子产生优秀个体,而在最差小生境中采用受限单纯形搜索产生优秀个体,从而构成基于单纯形的小生境混合遗传算法SimplexNich-HGA.最后用SimplexNiche-HGA、单纯形混合遗传算法Simplex-HGA 以及基本遗传算法SGA求函数Rosenbrock的极值,并进一步用SimplexNiche-HGA和Simplex-HGA 求多峰值函数Shubert的极值,验证算法的正确性和求多峰值函数的极值的效率. 相似文献
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The hybrid flow-shop scheduling problem with multiprocessor tasks finds its applications in real-time machine-vision systems among others. Motivated by this application and the computational complexity of the problem, we propose a genetic algorithm in this paper. We first describe the implementation details, which include a new crossover operator. We then perform a preliminary test to set the best values of the control parameters, namely the population size, crossover rate and mutation rate. Next, given these values, we carry out an extensive computational experiment to evaluate the performance of four versions of the proposed genetic algorithm in terms of the percentage deviation of the solution from the lower bound value. The results of the experiments demonstrate that the genetic algorithm performs the best when the new crossover operator is used along with the insertion mutation. This genetic algorithm also outperforms the tabu search algorithm proposed in the literature for the same problem. 相似文献
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In this study, the one-dimensional Bin Packing Problem (BPP) is approached. The BPP is a classical optimization problem that is known for its applicability and complexity. We propose a method that is referred to as the Grouping Genetic Algorithm with Controlled Gene Transmission (GGA-CGT) for Bin Packing. The proposed algorithm promotes the transmission of the best genes in the chromosomes without losing the balance between the selective pressure and population diversity. The transmission of the best genes is accomplished by means of a new set of grouping genetic operators, while the evolution is balanced with a new reproduction technique that controls the exploration of the search space and prevents premature convergence of the algorithm. The results obtained from an extensive computational study confirm that (1) promoting the transmission of the best genes improves the performance of each grouping genetic operator; (2) adding intelligence to the packing and rearrangement heuristics enhances the performance of a GGA; (3) controlling selective pressure and population diversity tends to lead to higher effectiveness; and (4) GGA-CGT is comparable to the best state-of-the-art algorithms, outperforming the published results for the class of instances Hard28, which appears to have the greatest degree of difficulty for BPP algorithms. 相似文献
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遗传算法的一种新颖编码研究 总被引:2,自引:0,他引:2
提出了一种新的基于N进制分部编码算子的遗传算法.该编码算子首先将每个基因值用N进制的浮点数表示,然后将其分为整数部分和小数部分,分别重新编码组成染色体;相应的选择、交叉、变异算子采用符号编码的思想,充分利用N进制浮点数的特点进行设计.在遗传算法开始阶段,该编码算子进行整数部分和小数部分的遗传操作,使得遗传算法在早期具有很强的全局搜索能力,避免陷入局部极值;在后期进行小数部分的遗传操作,使得遗传在后期具有很强的局部搜索能力,能够很快地搜索到全局极值.通过理论分析,证明了N进制分部编码算子与传统的浮点数编码和二进制编码算子相比具有优越性,并通过典型函数的仿真进行了验证. 相似文献
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Genetic K-means algorithm 总被引:41,自引:0,他引:41
Krishna K. Narasimha Murty M. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1999,29(3):433-439
In this paper, we propose a novel hybrid genetic algorithm (GA) that finds a globally optimal partition of a given data into a specified number of clusters. GA's used earlier in clustering employ either an expensive crossover operator to generate valid child chromosomes from parent chromosomes or a costly fitness function or both. To circumvent these expensive operations, we hybridize GA with a classical gradient descent algorithm used in clustering, viz. K-means algorithm. Hence, the name genetic K-means algorithm (GKA). We define K-means operator, one-step of K-means algorithm, and use it in GKA as a search operator instead of crossover. We also define a biased mutation operator specific to clustering called distance-based-mutation. Using finite Markov chain theory, we prove that the GKA converges to the global optimum. It is observed in the simulations that GKA converges to the best known optimum corresponding to the given data in concurrence with the convergence result. It is also observed that GKA searches faster than some of the other evolutionary algorithms used for clustering. 相似文献