Multimodal function optimizations with multiple maximums and multiple minimums using an improved PSO algorithm

In this paper, a multimodal function optimization problem consisting of multiple maximums and multiple minimums is solved using an improved particle swarm optimization (PSO) algorithm. In the proposed scheme, the original population needs to be randomly divided into two main groups in the first stage. One group is to tackle the maximum optimization of the multimodal function and the other then focuses on the function minimum optimization. In the second stage, each group is split up into several subgroups in order to seek for function optimums simultaneously. There is no relation among subgroups and each subgroup can individually seek for one of function optimums. To achieve that, it is necessary to enroll the best particle information of each subgroup. It means that the proposed structure contains a number of best particles, not a single global best particle. The third stage is to modify the velocity updating formula of the algorithm where the global best particle is simply replaced by the best particle of each subgroup. Under the proposed scheme, multiple maxima and minima of the multimodal function can probably be solved separately and synchronously. Finally, many different kinds of multimodal function problems are illustrated to certify the applicability of the presented method, including one maximum and one minimum, two maximums and two minimums, multiple maximums and multiple minimums, and a complex engineering optimization problem with inequality conditions.     

一种催化粒子群算法及其性能分析

针对粒子群算法（PSO）在解决高维、多模复杂问题时容易陷入局部最优的问题,提出了一种新颖的混合算法—催化粒子群算法（CPSO）。在CPSO优化过程中,种群中的粒子始终保持其个体历史最优值pbests。CPSO种群更新由改造PSO、横向交叉以及垂直交叉三个搜索算子交替进行,其中,每个算子产生的中庸解均通过贪婪思想产生占优解pbests,并作为下一个算子的父代种群。在CPSO中,纵横交叉算法（CSO）作为PSO的加速催化剂,一方面通过横向交叉改善PSO的全局收敛性能,另一方面通过纵向交叉维持种群的多样性。对6个典型benchmark函数的仿真结果表明,相比其它主流PSO变体,CPSO在全局收敛能力和收敛速率方面具有明显优势。     

Non-parametric particle swarm optimization for global optimization

In recent years, particle swarm optimization (PSO) has extensively applied in various optimization problems because of its simple structure. Although the PSO may find local optima or exhibit slow convergence speed when solving complex multimodal problems. Also, the algorithm requires setting several parameters, and tuning the parameters is a challenging for some optimization problems. To address these issues, an improved PSO scheme is proposed in this study. The algorithm, called non-parametric particle swarm optimization (NP-PSO) enhances the global exploration and the local exploitation in PSO without tuning any algorithmic parameter. NP-PSO combines local and global topologies with two quadratic interpolation operations to increase the search ability. Nineteen (19) unimodal and multimodal nonlinear benchmark functions are selected to compare the performance of NP-PSO with several well-known PSO algorithms. The experimental results showed that the proposed method considerably enhances the efficiency of PSO algorithm in terms of solution accuracy, convergence speed, global optimality, and algorithm reliability.     

基于随机惯性权重的简化粒子群优化算法

针对标准粒子群优化算法易出现早熟收敛、搜索速度慢及寻优精度低等缺陷, 提出一种基于随机惯性权重的简化粒子群优化算法。算法采用去除速度项的粒子群简化结构, 通过随机分布的方式获取惯性权重提高新算法的局部搜索和全局搜索能力, 并且学习因子采用异步变化的策略来改善粒子的学习能力。考虑到个体之间的相互影响关系, 每个粒子的个体极值用所有粒子个体极值的平均值代替。通过几个典型测试函数仿真及F-检验结果表明, 提出的算法在搜索速度、收敛精度、鲁棒性方面较已有改进算法有了显著提高, 并且具有摆脱陷入局部最优解的能力。     

Galactic Swarm Optimization: A new global optimization metaheuristic inspired by galactic motion

This paper proposes a new global optimization metaheuristic called Galactic Swarm Optimization (GSO) inspired by the motion of stars, galaxies and superclusters of galaxies under the influence of gravity. GSO employs multiple cycles of exploration and exploitation phases to strike an optimal trade-off between exploration of new solutions and exploitation of existing solutions. In the explorative phase different subpopulations independently explore the search space and in the exploitative phase the best solutions of different subpopulations are considered as a superswarm and moved towards the best solutions found by the superswarm. In this paper subpopulations as well as the superswarm are updated using the PSO algorithm. However, the GSO approach is quite general and any population based optimization algorithm can be used instead of the PSO algorithm. Statistical test results indicate that the GSO algorithm proposed in this paper significantly outperforms 4 state-of-the-art PSO algorithms and 4 multiswarm PSO algorithms on an overwhelming majority of 15 benchmark optimization problems over 50 independent trials and up to 50 dimensions. Extensive simulation results show that the GSO algorithm proposed in this paper converges faster to a significantly more accurate solution on a wide variety of high dimensional and multimodal benchmark optimization problems.     

带邻近粒子信息的粒子群算法

针对标准粒子群算法易出现早熟的问题,提出了一种带邻近粒子信息的粒子群算法。该算法中粒子位置的更新不仅包括自身最优和种群最优,还包括粒子目前位置最近粒子最优的信息。为了有效地平衡算法的全局探索和局部开发,并使其收敛于全局最优值,采用了时变加速因子策略,两个加速因子随进化代数线性变化。通过对5个经典测试函数优化的数值仿真实验并与其他粒子群算法的比较,结果表明了在平均最优值和成功率上都有所提高,特别是对多峰函数效果更加明显。     

Particle Swarm Optimization with Chaos-based Initialization for Numerical Optimization

Particle swarm optimization (PSO) is a population based swarm intelligence algorithm that has been deeply studied and widely applied to a variety of problems. However, it is easily trapped into the local optima and premature convergence appears when solving complex multimodal problems. To address these issues, we present a new particle swarm optimization by introducing chaotic maps (Tent and Logistic) and Gaussian mutation mechanism as well as a local re-initialization strategy into the standard PSO algorithm. On one hand, the chaotic map is utilized to generate uniformly distributed particles to improve the quality of the initial population. On the other hand, Gaussian mutation as well as the local re-initialization strategy based on the maximal focus distance is exploited to help the algorithm escape from the local optima and make the particles proceed with searching in other regions of the solution space. In addition, an auxiliary velocity-position update strategy is exclusively used for the global best particle, which can effectively guarantee the convergence of the proposed particle swarm optimization. Extensive experiments on eight well-known benchmark functions with different dimensions demonstrate that the proposed PSO is superior or highly competitive to several state-of-the-art PSO variants in dealing with complex multimodal problems.     

一种双态免疫微粒群算法

针对基本微粒群算法的缺陷,提出了一种双态免疫微粒群算法.把微粒群分为捕食与探索两种状态,处于捕食状态的精英粒子采用精英学习策略,指导精英粒子逃离局部极值;处于探索状态的微粒采用探索策略,扩大解的搜索空间,抑制早熟停滞现象.同时引入免疫系统的克隆选择和受体编辑机制,增强群体逃离局部极值及多模优化问题全局寻优能力.实验表明...     

Attributed multi-objective comprehensive learning particle swarm optimization for optimal security of networks

In particle swarm optimization (PSO) each particle uses its personal and global or local best positions by linear summation. However, it is very time consuming to find the global or local best positions in case of complex problems. To overcome this problem, we propose a new multi-objective variant of PSO called attributed multi-objective comprehensive learning particle swarm optimizer (A-MOCLPSO). In this technique, we do not use global or local best positions to modify the velocity of a particle; instead, we use the best position of a randomly selected particle from the whole population to update the velocity of each dimension. This method not only increases the speed of the algorithm but also searches in more promising areas of the search space. We perform an extensive experimentation on well-known benchmark problems such as Schaffer (SCH), Kursawa (KUR), and Zitzler–Deb–Thiele (ZDT) functions. The experiments show very convincing results when the proposed technique is compared with existing versions of PSO known as multi-objective comprehensive learning particle swarm optimizer (MOCLPSO) and multi-objective particle swarm optimization (MOPSO), as well as non-dominated sorting genetic algorithm II (NSGA-II). As a case study, we apply our proposed A-MOCLPSO algorithm on an attack tree model for the security hardening problem of a networked system in order to optimize the total security cost and the residual damage, and provide diverse solutions for the problem. The results of our experiments show that the proposed algorithm outperforms the previous solutions obtained for the security hardening problem using NSGA-II, as well as MOCLPSO for the same problem. Hence, the proposed algorithm can be considered as a strong alternative to solve multi-objective optimization problems.     

动态分级中心引力约束优化算法及工程应用

结合非固定多段罚函数处理约束条件,提出一种动态分级中心引力优化算法用于求解约束优化问题。该算法利用佳点集初始化个体以保证种群的多样性。在每次迭代过程中将种群分为两个子种群,分别用于全局搜索和局部搜索,根据搜索阶段动态调整子种群个体数目。对几个标准的测试问题和工程优化问题进行数值实验,结果表明该算法能处理不同的约束优化问题。     

A hybrid particle swarm optimization for job shop scheduling problem

A hybrid particle swarm optimization (PSO) for the job shop problem (JSP) is proposed in this paper. In previous research, PSO particles search solutions in a continuous solution space. Since the solution space of the JSP is discrete, we modified the particle position representation, particle movement, and particle velocity to better suit PSO for the JSP. We modified the particle position based on preference list-based representation, particle movement based on swap operator, and particle velocity based on the tabu list concept in our algorithm. Giffler and Thompson’s heuristic is used to decode a particle position into a schedule. Furthermore, we applied tabu search to improve the solution quality. The computational results show that the modified PSO performs better than the original design, and that the hybrid PSO is better than other traditional metaheuristics.     

基于速度夹角的粒子群协同优化算法

粒子群算法（PSO）是一种随机全局优化算法，在许多领域得到了广泛应用。针对PSO存在易陷入局部极值、进化后期收敛速度缓慢的缺点，提出一种基于速度夹角的粒子群协同优化算法（V-PSCO），并且引入了一种基于高斯分布的累积分布函数的惯性权重调整策略。将V-PSCO用于几种典型函数的优化问题，结果表明，V-PSCO具有更强的全局搜索能力，优化性能明显提高。     

Solving IIR system identification by a variant of particle swarm optimization

A variant of particle swarm optimization (PSO) is represented to solve the infinitive impulse response (IIR) system identification problem. Called improved PSO (IPSO), it makes significant enhancement over PSO. To begin with, the population initialization step makes use of golden ratio to segment solution space so as to obtain high-quality solutions. It is followed by all particles using different inertia weights in velocity updating step, which is beneficial for preserving the balance between global search and local search. Subsequently, IPSO uses normal distribution to disturb the global best particle, which enhances its capacity of escaping from the local optimums. The above three operations cannot only guarantee high-quality solutions, strong global search capacity, and fast convergence rate, but also avoid low diversity, excessive local search, and premature stagnation. These properties of IPSO make it much better suited for IIR system identification problems. IPSO is applied on 12 examples. The experimental results amply demonstrate the capability of IPSO toward obtaining the best objective function values in all the cases. Compared with the other four PSO approaches, IPSO has stronger convergence and higher stability which clearly points out its desirable performance in search accuracy and identifying efficiency.

     

哈夫曼编码的协同粒子群优化算法

针对粒子群优化（PSO）算法在优化问题过程中易陷入局部最优的问题,提出一种基于哈夫曼编码的协同粒子群优化（HC PSO）算法。采用哈夫曼编码将种群划分成2个子种群并对2个子种群进行独立优化,同时,2子种群之间协同完成搜索种群的全局最优解。采用6个标准测试函数来测试算法性能。实验结果表明,该算法可以有效地避免种群陷入局部最优,具有较好的优化性能和稳定性,收敛精度得到了显著的提高。     

基于混沌序列的多峰函数微粒群寻优算法

基于混沌序列的多峰函数微粒群寻优算法的目标就是找到多峰函数的所有局部优化峰值。在分析微粒群优化算法中各个参数对微粒运动影响的基础上,对微粒群算法进行改造,让微粒运动从初始位置沿优化函数曲线向优化峰值方向爬行,直至找到所在区域的局部优化峰值;要想求得尽可能多的局部优化峰值,就要求微粒群中微粒的初始位置分布具有随机性和遍历性,为此采用混沌序列设置微粒初始位置;为使每一个局部最优值点都可能有微粒群中的微粒经过,采用变步长的迭代计算;为防止优化函数曲线的某些局部峰附近没有微粒分布,从而漏掉该局部峰值,对计算进行重复,直至两轮求得的优化函数的局部峰值之差小于给定阈值。仿真结果表明,该算法具有很好的局部寻优特性,计算过程简捷,寻优效果良好,可有效地应用于多峰函数的局部寻优并求取全局最优值。     

Scale-free fully informed particle swarm optimization algorithm

This paper proposes a novel PSO algorithm, referred to as SFIPSO (Scale-free fully informed particle swarm optimization). In the proposed algorithm a modified Barabási-Albert (BA) model [4] is used as a self-organizing construction mechanism, in order to adaptively generate the population topology exhibiting scale-free property. The swarm population is divided into two subpopulations: the active particles and the inactive particles. The former fly around the solution space to find the global optima; whereas the latter are iteratively activated by the active particles via attaching to them, according to their own degrees, fitness values, and spatial positions. Therefore, the topology will be gradually generated as the construction process and the optimization process progress synchronously. Moreover, the cognitive effect and the social effect on the variance of a particle’s velocity vector are distributed by its “contextual fitness” value, and the social effect is further distributed via a time-varying weighted fully informed mechanism that originated from [27]. It is proved by the results of comparative experiments carried out on eight benchmark test functions that the scale-free population topology construction mechanism and the weighted fully informed learning strategy can provide the swarm population with stronger diversity during the convergent process. As a result, SFIPSO obtained success rate of 100% on all of the eight test functions. Furthermore, SFIPSO also yielded good-quality solutions, especially on multimodal test functions. We further test the network properties of the generated population topology. The results prove that (1) the degree distribution of the topology follows power-law, therefore exhibits scale-free property, and (2) the topology exhibits “disassortative mixing” property, which can be interpreted as an important condition for the reinforcement of population diversity.     

基于逻辑自映射的变尺度混沌粒子群优化算法*

针对基本粒子群优化算法的早熟收敛问题,提出了一种基于逻辑自映射的变尺度混沌粒子群优化算法。该算法在粒子群优化算法每次寻优结束时,采用逻辑自映射函数产生混沌序列,在已搜索到的精英粒子附近尝试搜索更优解并动态收缩搜索范围,在防止算法过早陷入局部最优的同时提高了算法搜索的精度。仿真结果表明,新算法在寻优成功率和平均最优值方面有很大提高,在求解包括欺骗性函数和高维函数在内的多种函数优化问题方面具有良好的效果。     

差分和扰动混合的多策略粒子群优化算法

通常的粒子群优化算法采取单一的学习策略,不利于搜索信息的有效保留,因此将改进的差分变异策略引入到粒子的速度更新中以增强算法的群体多样性;综合利用差分变异与扰动策略两种不同的产生新解的方式,提出了一种多策略交叉学习机制算法DPPSO（hybrid particle swarm optimization with differential and per-turbation）。每一个粒子通过引进的差分变异操作和扰动操作分别产生一个中间粒子,再选择较好的粒子作为当前粒子的新位置,从而实现所有粒子动态地选择更好的生成策略来更新自己的位置和速度,因此该交叉策略能够有效提高PSO算法的群体多样性和搜索路径的多样性,粒子可以获取更好的启发式信息,沿着不同的路径被引向更有潜力的搜索区域。实验结果表明了两种策略的有效性和互补性,DPPSO算法比其他三种算法有更好的综合表现,具有有效的全局收敛能力和准确定位能力。     

A hybrid niching PSO enhanced with recombination-replacement crowding strategy for multimodal function optimization

This paper presents a hybrid niching algorithm based on the PSO to deal with multimodal function optimization problems. First, we propose to evolve directly both the particle population and memory population (archive population), called the P&A pattern, to enhance the efficiency of the PSO for solving multimodal optimization functions, and investigate illustratively the niching capability of the PSO and the PSO_P&A. It is found that the global version PSO is disable, but the local version PSO_P&A is able, to niche multiple species for locating multiple optima. Second, the recombination-replacement crowding strategy that works on the archive population is introduced to improve the exploration capability, and the hybrid niching PSO_P&A (HN-PSO_P&A) is developed. Finally, experiments are carried out on multimodal functions for testing the niching efficiency and scalability of the proposed method, and it is verified that the proposed method has a sub-quadratic scalability with dimension in terms of fitness function evaluations on specific MMFO problems.     

带自适应感知能力的粒子群优化算法

提出一种求解约束优化问题的改进粒子群优化算法。它利用可行性判断规则处理约束条件,更新个体最优解和全局最优解。通过为粒子赋予自适应感知能力,算法能较好地平衡全局和局部搜索,且有能力跳出局部极值,防止早熟。边界附近粒子的感知结果被用来修正其飞行速度以加强算法对约束边界的搜索。实验结果表明,新算法收敛速度快,寻优能力强,能很好地求解约束优化问题。