信息迁移多任务优化共生生物搜索算法

针对现有共生生物搜索（SOS）算法只能求解单个任务,以及信息负迁移影响多任务优化（MTO）性能这两个难题,提出一个信息迁移多任务优化共生生物搜索（ITMTSOS）算法。首先基于多种群演化MTO框架,根据任务个数设置相应数量种群;然后各种群独立运行基本SOS算法,当某一种群连续若干代停滞进化时,引入个体自身最优经验和邻域最优个体以形成知识模块并将该模块迁移至该种群个体进化过程中;最后对ITMTSOS算法时间和空间复杂度进行分析。仿真实验结果表明,ITMTSOS算法同时求解多个不同形态高维函数时均能快速收敛至全局极值解0,与单任务SOS算法相比,平均运行时间最多缩短约25.25%;而在同时求解多维0/1背包问题和师生匹配问题时,所提算法在测试集weing1和weing7上的最优适应值与目前测试集公布的最优结果相比分别提高了22 767和22 602,师生最优匹配差和平均匹配差的绝对值分别下降了26和33,平均运行时间约缩短了7.69%。     

自适应精英反向学习共生生物搜索算法

针对共生生物搜索算法在求解高维复杂问题时存在过早收敛,求解精度不高及后期搜索迟滞等问题,结合自适应思想,利用不同差分扰动项和精英反向学习策略对算法进行改进,得到一种改进的共生生物搜索算法。对14个标准测试函数的仿真实验结果进行分析,相比于原算法和其他三种目前流行的算法,改进算法在收敛速度和求解精度方面均具有明显的优势,寻优能力更强。     

面向路径规划问题的虚拟多任务共生生物搜索算法

针对现有共生生物搜索(SOS)算法在求解路径规划等离散型优化问题时存在性能较差、收敛速度慢等问题,提出虚拟多任务共生生物搜索(VMTSOS)算法。首先根据双向映射解码策略,实现个体连续空间位置和离散城市序列转换;然后引入多任务优化思想构建虚拟多任务环境,设计多种群同时优化同一任务,并通过停滞阈值控制种群间信息迁移频率,当主种群达到停滞阈值时,将辅助种群中部分优秀个体替换为主种群劣质个体;最后对VMTSOS算法时间和空间复杂度进行分析。仿真实验表明,VMTSOS算法在求解多数TSP时均能快速收敛至各测试实例目前的最优解,而在求解冷链物流配送问题时,具有多种群辅助机制的VMTSOS算法能较大程度地降低最优总成本。     

基于子种群拉伸操作的精英共生生物搜索算法

针对共生生物搜索算法存在易早熟、收敛速度慢等缺陷,提出一种基于子种群拉伸操作的精英共生生物搜索算法.在“互利共生”阶段,根据适应度值将种群划分为两个子种群,设计有针对性的进化策略,使两个子种群分别负责开发和探索,有效地平衡算法的收敛速度与精度;在“偏利共生”阶段,利用最优个体的方向性引导信息,引入拉伸因子和差分扰动向量,并修正个体更新模式,从而在提高算法收敛速度的同时保证种群的多样性;模拟寄生体和宿主的生物关系,提出精英“寄生”机制,进一步平衡算法在整个迭代过程中的探索与开发能力.对与标准共生生物算法、改进后的共生生物搜索算法以及其他4个群智能进化算法在17个函数上的测试结果进行比较分析,结果表明所提出的算法精度更佳,收敛速度优势明显.     

基于改进共生生物搜索算法的林火图像多阈值分割

针对传统多阈值分割方法计算复杂度随着阈值个数的增加而增长,以及对给定图像进行多阈值分割操作时效率很低等问题,提出了一种基于共生生物搜索(SOS)算法结合Kapur熵的多阈值分割方法.首先将精英反策略(EOBL)引入到SOS算法的共栖阶段,从而改善传统SOS算法处理复杂优化问题时易陷入局部最优的问题;然后引入莱维飞行策略...     

学习策略布谷鸟搜索算法

由于布谷鸟搜索算法中的布谷鸟具有相同的搜索策略,而类似的搜索方法使得布谷鸟容易陷入局部极值,因此本文提出了一种结合粒子群算法思想和优化莱维机制的新算法——学习策略布谷鸟搜索算法.该算法将权重参数引入莱维机制中,以增大算法在后期搜索到优质解的概率.本文选取了文献中的7个基准函数用于测试学习策略布谷鸟搜索算法的性能,将其与...     

基于混合策略改进的麻雀搜索算法

为克服基本麻雀搜索算法(Sparrow Search Algorithm, SSA)存在的迭代过程中种群多样性减少、易陷入局部最优停滞、早熟收敛等不足,提出一种基于混合策略改进的麻雀搜索优化算法(EGSSA)。首先,迭代时利用精英反向学习机制在个体求解过程中计算精英反向解,提升算法寻优过程中种群丰富性和种群质量,为提高算法全局寻优能力以及收敛精度奠定基础;其次,将黄金正弦策略用以改进发现者位置更新方式,协调算法局部开发和全局搜索能力,并且提高算法的收敛能力;最后,在加入者的更新中采用了莱维飞行随机步长,以使新加入者所搜索的范围更为全面,一定程度避免算法陷入“早熟收敛”。选取12个基准测试函数进行仿真实验,分别与4种元启发式算法以及3种改进麻雀搜索算法进行比较,实验结果以及Wilcoxon秩和检验均表明,EGSSA算法具有更好的全局探索能力和稳定性以及较强跳出局部极值的能力。     

混合策略改进的乌鸦搜索算法

为了改善乌鸦搜索算法(crow search algorithm,CSA)收敛速度慢、收敛精度不足的问题,提出一种混合策略改进的乌鸦搜索算法(MSCSA).首先在算法运行前期引入tent序列扰动的自适应权重系数,提高算法收敛速度;其次在算法后期引入混合黄金正弦与飞蛾扑火算子,避免算法后期陷入局部最优值;最后通过改进算法的发现概率AP,增加算法的随机性从而提高算法的收敛精度.通过在九个基准函数上对比测试,确定迭代系数的取值,通过Wilcoxon秩和测试验证算法性能.实验结果证明,所提出的MSCSA的性能更为优秀.     

基于差分进化的布谷鸟搜索算法

针对基本布谷鸟搜索算法局部搜索能力弱、寻优精度低等不足,提出了一种具有差分进化策略的改进布谷鸟搜索算法。该算法是在种群进入下一次迭代之前在其个体上增加两个带权的差来实现个体变异,再对其进行交叉、选择操作得到最优个体,使缺乏变异机制的布谷鸟搜索算法具有变异能力,从而提高布谷鸟搜索算法的多样性,避免种群个体陷入局部最优,增强算法全局寻优能力。对几种经典测试函数和1个典型应用实例进行测试,仿真实验结果表明,新算法具有更好的全局搜索能力,在收敛精度、收敛速度以及寻优成功率等性能上显著优于基本布谷鸟搜索算法。     

采用改进型SOS算法的光伏组件模型参数辨识

针对当前大部分光伏（photovoltaic,PV）模型参数辨识算法均存在准确性低和可靠性差等问题,提出了一种采用改进型共生生物搜索算法（symbiotic organisms search,SOS）的光伏组件模型参数辨识方法。首先,为提高标准SOS算法的寻优性能,提出了新的改进型SOS算法,记作ImSOS算法。该算法在标准SOS算法的生物种群初始化阶段采用了准反射学习机制;在互利共生搜索阶段采用了改进受益因子策略;在偏利共生搜索阶段采用了收缩随机数产生因子区间策略。其次,给出了采用ImSOS算法求解基于实验测量电流—电压（I-V）数据的光伏组件模型参数辨识问题的具体步骤及实现流程。最后,利用实际Sharp ND-R250A5光伏组件进行实验,通过与标准SOS算法以及其他七种新颖智能优化算法进行对比验证,结果表明了ImSOS算法在光伏组件模型参数辨识的有效性和优越性。可见ImSOS算法为准确可靠地辨识光伏组件模型参数提供了一种新的有效方法。     

A modified symbiotic organisms search (mSOS) algorithm for optimization of pin-jointed structures

The paper introduces a modified symbiotic organisms search (mSOS) algorithm to optimization of pin-jointed structures including truss and tensegrity ones. This approach is refined from the original SOS with five modifications in the following three phases: mutualism, commensalism and parasitism. In the mutualism one, benefit factors are suggested as 1 to equally represent the level of benefit to each organism, whilst the best organism is replaced by a randomly selected one to increase the global search capability. With the aim of improving the convergence speed, randomly created coefficients in the commensalism phase are restricted in the range [0.4, 0.9]. Additionally, an elitist technique is applied to this phase to filter the best organisms for the next generation as well. Finally, the parasitism phase is eliminated to simplify the implementation and reduce the time-consuming process. To verify the effectiveness and robustness of the proposed algorithm, five examples relating to truss weight minimization with discrete design variables are performed. Additionally, two examples regarding minimization a function of eigenvalues and force densities of tensegrity structures with continuous design variables are considered further. Optimal results acquired in all illustrated examples reveal that the proposed method requires fewer number of analyses than the original SOS and the DE, but still gaining high-quality solutions. Furthermore, the mSOS also outperforms numerous other algorithms in available literature in terms of optimal solutions, especially for problems with a large number of design variables.     

Oppositional symbiotic organisms search optimization for multilevel thresholding of color image

Selection of optimal threshold is the most crucial issue in threshold-based segmentation. In case of color image, this task is become challenging, because conventional color image segmentation has computational complexity and also it suffers from lack of accuracy. Various techniques such as threshold based, region growing, edge detection, graph cut, pixel classification, neural network, active contour, gray level co-occurrence matrix are proposed so far for image segmentation in the literature. Out of them, threshold-based segmentation is popular for its simplicity. To address the problem of color image segmentation, we propose an enhanced version of metaheuristic optimization algorithm called Opposition based Symbiotic Organisms Search (OSOS) to solve multilevel image thresholding technique for color image segmentation by introducing opposition based learning concepts to accelerate the convergence rate and enhance the performance of standard symbiotic organisms search (SOS). The performance of the proposed OSOS based algorithm is investigated thoroughly and compared with some existing techniques like Cuckoo Search (CS), BAT algorithm (BAT), artificial bee colony (ABC) and particle swarm optimization (PSO). The comparison is made by applying the algorithm to a set of color images taken from a well-known benchmark dataset (Berkeley Segmentation Dataset (BSDS)) and some of the color images collected for the COCO dataset. It is observed from the results that the performance of the OSOS based algorithm is promising with respect to standards SOS and others in terms of the values of objective functions as well as the values of some well-defined quality metrics such as peak signal-to-noise ratio (PSNR), structure similarity index (SSIM) and feature similarity index (FSIM). The results of the proposed algorithm may encourage the scientists and engineers to apply it into pattern recognition problems.     

DG placement in radial distribution network by symbiotic organisms search algorithm for real power loss minimization

Incorporation of distributed generation (DG) in distribution network may reduce the network loss if DG of appropriate size is placed at proper strategic location. The current article presents determination of optimal size and location of DG in radial distribution network (RDN) for the reduction of network loss considering deterministic load demand and DG generation using symbiotic organisms search (SOS) algorithm. SOS algorithm is a meta-heuristic technique, inspired by the symbiotic relationship between different biological species. In this paper, optimal size and location of DG are obtained for two different RDNs (such as, 33-bus and 69-bus distribution networks). The obtained results, using the proposed SOS, are compared to the results offered by some other optimization algorithms like particle swarm optimization, teaching-learning based optimization, cuckoo search, artificial bee colony, gravitational search algorithm and stochastic fractal search. The comparison is done based on minimum loss of the distribution network as well as based on the convergence mobility of the fitness function offered by each of the comparative algorithms for both the networks under consideration. It is established that the proposed SOS algorithm offers better result as compared to other optimization algorithms under consideration. The results are also compared to the existing solution available in the literature.     

基于逐维反向学习的动态适应布谷鸟算法

为了解决布谷鸟搜索算法寻优精度不高、收敛速度慢、后期搜索活力不足以及处理高维优化问题时存在维间干扰等缺陷,提出了逐维反向学习策略的动态适应布谷鸟算法。首先,对选择更新后的解进行逐维反向学习,减少维间干扰,扩大种群多样性;然后,使用精英保留方式评价该结果,提高算法寻优能力;最后,充分利用当前解的信息进行动态适应的缩放因子控制,引导解快速收敛,提升算法搜索活力。实验结果表明,该算法相比较于标准布谷鸟搜索算法,寻优精度、收敛速度以及后期搜索活力有所提高,与其他改进算法相比也具有一定的竞争优势。     

Symbiotic organisms search algorithm for dynamic economic dispatch with valve-point effects

Abstract

In this study, symbiotic organisms search (SOS) algorithm is proposed to solve the dynamic economic dispatch with valve-point effects problem, which is one of the most important problems of the modern power system. Some practical constraints like valve-point effects, ramp rate limits and prohibited operating zones have been considered as solutions. Proposed algorithm was tested on five different test cases in 5 units, 10 units and 13 units systems. The obtained results have been compared with other well-known metaheuristic methods reported before. Results show that proposed algorithm has a good convergence and produces better results than other methods.     

A novel symbiotic organisms search algorithm for congestion management in deregulated environment

Abstract

In today’s competitive electricity market, managing transmission congestion in deregulated power system has created challenges for independent system operators to operate the transmission lines reliably within the limits. This paper proposes a new meta-heuristic algorithm, called as symbiotic organisms search (SOS) algorithm, for congestion management (CM) problem in pool based electricity market by real power rescheduling of generators. Inspired by interactions among organisms in ecosystem, SOS algorithm is a recent population based algorithm which does not require any algorithm specific control parameters unlike other algorithms. Various security constraints such as load bus voltage and line loading are taken into account while dealing with the CM problem. In this paper, the proposed SOS algorithm is applied on modified IEEE 30- and 57-bus test power system for the solution of CM problem. The results, thus, obtained are compared to those reported in the recent state-of-the-art literature. The efficacy of the proposed SOS algorithm for obtaining the higher quality solution is also established.     

Soft sets based symbiotic organisms search algorithm for resource discovery in cloud computing environment

The dynamicity, coupled with the uncertainty that occurs between advertised resources and users’ resource requirement queries, remains significant problems that hamper the discovery of candidate resources in a cloud computing environment. Network size and complexity continue to increase dynamically which makes resource discovery a complex, NP-hard problem that requires efficient algorithms for optimum resource discovery. Several algorithms have been proposed in literature but there is still room for more efficient algorithms especially as the size of the resources increases. This paper proposes a soft-set symbiotic organisms search (SSSOS) algorithm, a new hybrid resource discovery solution. Soft-set theory has been proved efficient for tackling uncertainty problems that arises in static systems while symbiotic organisms search (SOS) has shown strength for tackling dynamic relationships that occur in dynamic environments in search of optimal solutions among objects. The SSSOS algorithm innovatively combines the strengths of the underlying techniques to provide efficient management of tasks that need to be accomplished during resource discovery in the cloud. The effectiveness and efficiency of the proposed hybrid algorithm is demonstrated through empirical simulation study and benchmarking against recent techniques in literature. Results obtained reveal the promising potential of the proposed SSSOS algorithm for resource discovery in a cloud environment.     

Symbiotic organisms search algorithm for optimal evolutionary controller tuning of fractional fuzzy controllers

With the development of technology and the practical needs of complex engineering applications, fuzzy controllers have been widely applied. In contrast to a traditional integer-order fuzzy controller, a fractional fuzzy controller can extend the integral and differential order of a fuzzy controller to any real number, which describes the controlled object more accurately and enhances its control performance. However, a fractional fuzzy controller has a larger number of control parameters, which makes it difficult to calibrate. Because the parameter controller tuning values of the fuzzy controller clearly influence its control performance, this paper proposes to optimize the parameter controller tuning process using the symbiotic organisms search algorithm. A large number of simulation tests were carried out to compare the symbiotic organisms search-based parameter controller tuning method with parameter controller tuning based on five other representative swarm intelligence algorithms. The experimental results show that the symbiotic organisms search algorithm better optimizes the parameters of the fractional fuzzy controller.