斥力势场下的多粒子群协同动态优化算法及其应用

动态环境下的优化问题是当前智能计算领域一个研究热点.针对当前多种群动态优化存在的问题,提出一种基于斥力势场的多粒子群协同优化算法,利用多个种群并行搜索,当发现局部极值点后,在局部极值点处建立人工斥力势场,防止多种群对该区域重复搜索,当环境变化时,采用柯西变异对种群进行初始化,通过对DF仿真,验证了改进算法具有较好的跟踪性能.另外,本文从数学上证明了多种群搜索的优越性,分析了柯西变异优于其它变异的原因,为算法的改进策略提供了理论依据.最后将该方法应用于动态系统PID控制器的参数整定上,获得了满意的控制效果.     

一种多粒子群协同进化算法

为进一步提高多粒子群协同进化算法的寻优精度, 并有效改善粒子群易陷入局部极值及收敛速度慢的问题, 结合遗传算法较强的全局搜索能力和极值优化算法的局部搜索能力, 提出了一种改进的多粒子群协同进化算法. 对粒子群优化算法提出改进策略, 并在种群进化过程中, 利用遗传算法增加粒子的多样性及优良性, 经过一定次数的迭代, 利用极值优化算法加快收敛速度. 实验结果表明该算法具有较好的性能, 能够摆脱陷入局部极值点的问题, 并具有较快的收敛速度.     

基于动态多种群粒子群支持向量机的短期负荷预测

针对标准粒子群优化(PSO)算法存在易陷入局部极值点的缺点,提出了一种基于物种概念的动态多种群粒子群优化算法(DMPSO).在DMPSO中引入了物种概念,在进化过程中动态确定物种,利用种群多样性信息动态调整物种半径,通过物种对解空间的不同区域进行搜索,最终确定出各极值点.将DMPSO算法和支持向量机(SVM)相结合,形成了解决电力系统短期负荷预测问题的新方法(DMPSO-SVM).在该方法中利用DMPSO算法来优化SVM中的参数,利用快速傅立叶变换(FFT)进行频谱分析并确定SVM的输入量.电力系统短期负荷预测的实际算例表明,与传统预测方法相比,该方法具有更高的预测精度和鲁棒性.     

动态环境下粒子分群与种群多样性的关系研究

如何构建策略解决动态优化问题一直是智能计算研究的重点.采用种群熵来刻画粒子群算法中群体的多样性,在由DF1(Dynamic Function 1)生成的动态环境下分析了4种不同粒子群方法中群体的多样性以及对动态目标点的跟踪效果.实验结果表明,动态环境下,群体多样性保持能够影响算法的跟踪效果.可以通过调整分群比例来改变群体的多样性,进而在不同的动态环境下采取不同比例的分群策略以达到较好的跟踪效果.     

一种基于栅格的动态粒子数微粒群算法

微粒群算法的全局搜索性能容易受到局部极值点的影响,对此,提出一种基于栅格的动态粒子数微粒群算法(GB-DPPPSO).通过设计栅格信息更新策略、粒子产生策略和粒子消灭策略,可以根据种群搜索情况动态控制粒子数变化,以保持种群多样性,提高全局搜索性能,通过对4个典型数学验证函数的仿真实验,表明了该算法相对于DPPPSO)在全局搜索成功率和搜索效率两方面均有明显改进.     

一种面向多模函数改进的果蝇优化算法

为将果蝇优化算法有效应用在多模函数优化问题中,设计了一种优化多模函数的果蝇优化算法—基于佳点集和小生境技术的混合果蝇优化算法。首先引入数论中的佳点集概念构造初始种群,使其较均匀地分布在可行域中并且产生的模式多样性比随机分布更好,提高了算法的搜索能力及效率和稳定性;其次用小生境技术改进算法的搜索模式,更好地维持了种群的多样性使种群能快速定位较多的峰;再通过小生境熵来量化群体的多样性并选择进化方向,当小生境熵低于设定的阈值时,结合佳点搜索产生新群体给以扰动,以维持种群的多样性,否则对各个峰进行精细搜索。对七个测试函数分别进行两类仿真,结果表明,该算法不仅能够高效且高精度地找到全局极值而且能够以较高的精度定位到所有全局极值和多个次优极值,显示了较强的多峰搜索能力。     

多峰函数优化的改进群居蜘蛛优化算法

针对群居蜘蛛优化（SSO）算法求解复杂多峰函数成功率不高和收敛精度低的问题,提出了一种自适应多种群回溯群居蜘蛛优化（AMBSSO）算法。引入自适应决策半径概念,动态地将蜘蛛种群分成多个种群,种群内适应度不同的个体采取不同的更新方式,提高了种群样本多样性;提出回溯迭代进化策略,在筛选全局极值的基础上,根据进化程度执行回溯迭代更新,保证了算法全局寻优能力。高维多峰函数仿真结果表明,同SSO算法、PSO算法等优化算法相比,AMBSSO算法具有较快的收敛速度和较高的收敛精度,尤其适用复杂高维多峰函数优化问题。     

动态环境下一种具有记忆能力的分布估计算法

以概率模型为基本记忆元素,对动态优化过程中所产生的历史信息进行记忆和利用,提出一种具有记忆能力的分布估计算法用以求解二进制编码动态优化问题.设计了基于环境辨识技术的记忆管理策略,并对种群多样性进行动态补偿.实验结果表明,该算法具有良好的通用性,所采用的多样性补偿策略能够保证算法种群对最优解的持续搜索能力.在对5个动态优化问题的实验中,该算法在绝大多数情况下都显著优于现有的另外两种动态进化算法.     

基于动态自适应的双档案大规模稀疏优化算法

针对传统大规模优化算法维数过高、过度稀疏、难以平衡等问题,文中提出基于动态自适应的双档案大规模稀疏优化算法,平衡维数和稀疏性对算法的影响,提高算法在解决大规模优化问题上的多样性和收敛性.首先,改变种群分数生成策略,加入自适应参数和惯性权重,增加分数的动态性,改善种群的多样性,使搜索不易陷入局部最优.然后,改变算法的环境...     

面向多峰函数优化的PASFLI算法及应用

针对基本混合蛙跳算法在高维多峰函数优化时早熟及难以找到所有全局极值的问题,提出了一种具有混合智能的多态子种群自适应混合蛙跳免疫算法,证明了算法以概率1收敛于全局最优解。该算法采用双层进化模式,融合了混合蛙跳、免疫克隆选择技术。在低层混合蛙跳操作中,加入了多态自适应子种群机制,提高了子种群多样性,有效抑制了早熟现象;在算法进化后期,提出了全局极值筛选策略,将子种群极值点提升到高层免疫克隆选择操作,进一步提高了全局寻优能力。通过复杂多峰函数仿真实验,表明该算法能够快速有效地给出全部全局最优解。     

An adaptive optimization technique for dynamic environments

The use of evolutionary algorithms (EAs) is beneficial for addressing optimization problems in dynamic environments. The objective function for such problems changes continually; thus, the optimal solutions likewise change. Such dynamic changes pose challenges to EAs due to the poor adaptability of EAs once they have converged. However, appropriate preservation of a sufficient level of individual diversity may help to increase the adaptive search capability of EAs. This paper proposes an EA-based Adaptive Dynamic OPtimization Technique (ADOPT) for solving time-dependent optimization problems. The purpose of this approach is to identify the current optimal solution as well as a set of alternatives that is not only widespread in the decision space, but also performs well with respect to the objective function. The resultant solutions may then serve as a basis solution for the subsequent search while change is occurring. Thus, such an algorithm avoids the clustering of individuals in the same region as well as adapts to changing environments by exploiting diverse promising regions in the solution space. Application of the algorithm to a test problem and a groundwater contaminant source identification problem demonstrates the effectiveness of ADOPT to adaptively identify solutions in dynamic environments.     

Immigrant schemes for evolutionary algorithms in dynamic environments: Adapting the replacement rate

One approach for evolutionary algorithms (EAs) to address dynamic optimization problems (DOPs) is to maintain diversity of the population via introducing immigrants.So far all immigrant schemes developed for EAs have used fixed replacement rates.This paper examines the impact of the replacement rate on the performance of EAs with immigrant schemes in dynamic environments,and proposes a self-adaptive mechanism for EAs with immigrant schemes to address DOPs.Our experimental study showed that the new approach ...     

Population-Based Incremental Learning With Associative Memory for Dynamic Environments

In recent years, interest in studying evolutionary algorithms (EAs) for dynamic optimization problems (DOPs) has grown due to its importance in real-world applications. Several approaches, such as the memory and multiple population schemes, have been developed for EAs to address dynamic problems. This paper investigates the application of the memory scheme for population-based incremental learning (PBIL) algorithms, a class of EAs, for DOPs. A PBIL-specific associative memory scheme, which stores best solutions as well as corresponding environmental information in the memory, is investigated to improve its adaptability in dynamic environments. In this paper, the interactions between the memory scheme and random immigrants, multipopulation, and restart schemes for PBILs in dynamic environments are investigated. In order to better test the performance of memory schemes for PBILs and other EAs in dynamic environments, this paper also proposes a dynamic environment generator that can systematically generate dynamic environments of different difficulty with respect to memory schemes. Using this generator, a series of dynamic environments are generated and experiments are carried out to compare the performance of investigated algorithms. The experimental results show that the proposed memory scheme is efficient for PBILs in dynamic environments and also indicate that different interactions exist between the memory scheme and random immigrants, multipopulation schemes for PBILs in different dynamic environments.     

Improved differential evolution approach based on cultural algorithm and diversity measure applied to solve economic load dispatch problems

Evolutionary algorithms (EAs) are general-purpose stochastic search methods that use the metaphor of evolution as the key element in the design and implementation of computer-based problems solving systems. During the past two decades, EAs have attracted much attention and wide applications in a variety of fields, especially for optimization and design. EAs offer a number of advantages: robust and reliable performance, global search capability, little or no information requirement, and others. Among various EAs, differential evolution (DE), which characterized by the different mutation operator and competition strategy from the other EAs, has shown great promise in many numerical benchmark problems and real-world optimization applications. The potentialities of DE are its simple structure, easy use, convergence speed and robustness. To improve the global optimization property of DE, in this paper, a DE approach based on measure of population's diversity and cultural algorithm technique using normative and situational knowledge sources is proposed as alternative method to solving the economic load dispatch problems of thermal generators. The traditional and cultural DE approaches are validated for two test systems consisting of 13 and 40 thermal generators whose nonsmooth fuel cost function takes into account the valve-point loading effects. Simulation results indicate that performance of the cultural DE present best results when compared with previous optimization approaches in solving economic load dispatch problems.     

复杂非凸约束优化难题与迭代动态多样进化算法

进化算法的迅速发展,为非凸约束优化问题的求解提供了有效途径,但目前常用优化算法还未能全面满足更为复杂的约束条件或目标分布对寻优方式灵活应变能力的特别需求.首先,本文研究发现,当优化问题在全局最优解的某一较小邻域内,依然分布有复杂的局部极值或可行域分布时,大多数进化算法中不灵活的探索与挖掘方式将会在寻优后期导致误收敛现象发生.其次,为解决这一难题,本文继续对问题特征与算法规则进行了深入探讨,并提出用于解决该类问题的迭代动态多样进化算法(IDDEA).该算法利用多智能体创建一种新型占优评估策略,并以此为基础设计出较优子区域的划分方式.本文所提子区域的划分,在充分发挥动态多样搜索进化方式的探索能力前提下迭代推进,逐步缩小寻优空间,进而使得寻优采样在收敛的同时,依然保持原有探索与挖掘的灵活权衡模式.再次,本文还提出一种最小惩罚函数,为IDDEA引入一种自适应惩罚机制,来动态调整不可行代理的适应度分配,从而有效避免了选择罚系数的难题.最后,IDDEA在若干工程优化设计问题中的成功应用表明,本文在合理的问题分析基础上,提供了更加有效的算法设计思路与成果.     

复杂非凸约束优化难题与迭代动态多样进化算法（英文）

Evolutionary algorithms(EAs) were shown to be effective for complex constrained optimization problems. However,inflexible exploration in general EAs would lead to losing the global optimum nearby the ill-convergence regions. In this paper, we propose an iterative dynamic diversity evolutionary algorithm(IDDEA) with contractive subregions guiding exploitation through local extrema to the global optimum in suitable steps. In IDDEA, a novel optimum estimation strategy with multi-agents evolving diversely is suggested to efficiently compute dominance trend and establish a subregion. In addition, a subregion converging iteration is designed to redistrict a smaller subregion in current subregion for next iteration, which is based on a special dominance estimation scheme. Meanwhile, an infimum penalty function is embedded into IDDEA to judge agents and penalize adaptively the unfeasible agents with the lowest fitness of feasible agents. Furthermore, several engineering design optimization problems taken from the specialized literature are successfully solved by the present algorithm with high reliable solutions.     

Multiobjective evolutionary algorithms: a comparative case studyand the strength Pareto approach

Evolutionary algorithms (EAs) are often well-suited for optimization problems involving several, often conflicting objectives. Since 1985, various evolutionary approaches to multiobjective optimization have been developed that are capable of searching for multiple solutions concurrently in a single run. However, the few comparative studies of different methods presented up to now remain mostly qualitative and are often restricted to a few approaches. In this paper, four multiobjective EAs are compared quantitatively where an extended 0/1 knapsack problem is taken as a basis. Furthermore, we introduce a new evolutionary approach to multicriteria optimization, the strength Pareto EA (SPEA), that combines several features of previous multiobjective EAs in a unique manner. It is characterized by (a) storing nondominated solutions externally in a second, continuously updated population, (b) evaluating an individual's fitness dependent on the number of external nondominated points that dominate it, (c) preserving population diversity using the Pareto dominance relationship, and (d) incorporating a clustering procedure in order to reduce the nondominated set without destroying its characteristics. The proof-of-principle results obtained on two artificial problems as well as a larger problem, the synthesis of a digital hardware-software multiprocessor system, suggest that SPEA can be very effective in sampling from along the entire Pareto-optimal front and distributing the generated solutions over the tradeoff surface. Moreover, SPEA clearly outperforms the other four multiobjective EAs on the 0/1 knapsack problem     

An improved firefly algorithm for solving dynamic multidimensional knapsack problems

There is a wide range of publications reported in the literature, considering optimization problems where the entire problem related data remains stationary throughout optimization. However, most of the real-life problems have indeed a dynamic nature arising from the uncertainty of future events. Optimization in dynamic environments is a relatively new and hot research area and has attracted notable attention of the researchers in the past decade. Firefly Algorithm (FA), Genetic Algorithm (GA) and Differential Evolution (DE) have been widely used for static optimization problems, but the applications of those algorithms in dynamic environments are relatively lacking. In the present study, an effective FA introducing diversity with partial random restarts and with an adaptive move procedure is developed and proposed for solving dynamic multidimensional knapsack problems. To the best of our knowledge this paper constitutes the first study on the performance of FA on a dynamic combinatorial problem. In order to evaluate the performance of the proposed algorithm the same problem is also modeled and solved by GA, DE and original FA. Based on the computational results and convergence capabilities we concluded that improved FA is a very powerful algorithm for solving the multidimensional knapsack problems for both static and dynamic environments.     

A bi-population based scheme for an explicit exploration/exploitation trade-off in dynamic environments

Optimisation in changing environments is a challenging research topic since many real-world problems are inherently dynamic. Inspired by the natural evolution process, evolutionary algorithms (EAs) are among the most successful and promising approaches that have addressed dynamic optimisation problems. However, managing the exploration/exploitation trade-off in EAs is still a prevalent issue, and this is due to the difficulties associated with the control and measurement of such a behaviour. The proposal of this paper is to achieve a balance between exploration and exploitation in an explicit manner. The idea is to use two equally sized populations: the first one performs exploration while the second one is responsible for exploitation. These tasks are alternated from one generation to the next one in a regular pattern, so as to obtain a balanced search engine. Besides, we reinforce the ability of our algorithm to quickly adapt after cnhanges by means of a memory of past solutions. Such a combination aims to restrain the premature convergence, to broaden the search area, and to speed up the optimisation. We show through computational experiments, and based on a series of dynamic problems and many performance measures, that our approach improves the performance of EAs and outperforms competing algorithms.     

求解动态优化问题的多群体UMDA

提出一种求解动态优化问题的多群体单变量边缘分布算法(MUMDA).首先,利用多个概率模型(对应多个群体)将搜索空间分成几个部分,通过对不同区域的搜索或探索将好解进行迁移,扩大搜索空间,增加种群多样性,跟踪最优解的变化;然后,利用对UMDA收敛性的证明分析了所提出算法的有效性;最后,对两个动态优化问题进行仿真计算,并与传统UMDA和基于随机迁移的UMDA(iUMDA)进行了比较.结果表明,MUMDA能快速适应环境的变化,跟踪最优解.