Backtracking biogeography-based optimization for numerical optimization and mechanical design problems

As a novel Evolutionary Algorithm (EA), Biogeography-Based Optimization (BBO), inspired by the science of biogeography, draws much attention due to its significant performance in both numerical simulations and practical applications. In BBO, the features in poor solutions have a large probability to be replaced by the features in good solutions. The replacement operator is termed migration. However, the replacement causes a loss of the features in poor solutions, breaks the diversity of population and may lead to a local optimal solution. To overcome this, we design a novel migration operator to propose Backtracking BBO (BBBO). In BBBO, besides the regular population, an external population is employed to record historical individuals. The size of external population is the same as the size of regular population. The external population and regular population are used together to generate the next population. After that, the individuals in external population are randomly selected to be updated by the individuals in current population. In this way, the external population in BBBO can be considered as a memory to take part in the evolutionary process. The memory takes into account both current and historical data to generate next population, which enhances algorithm’s ability in exploring searching space. In numerical simulation, 14 classical benchmarks are employed to test BBBO’s performance and several classical nature inspired algorithms are use in comparison. The results show that the strategy in BBBO is feasible and very effective to enhance algorithm’s performance. In addition, we apply BBBO to mechanical design problems which involve constraints in optimization. The comparison results also exhibit that BBBO is very competitive in solving practical optimization problems.     

A novel two-archive strategy for evolutionary many-objective optimization algorithm based on reference points

Current evolutionary many-objective optimization algorithms face two challenges: one is to ensure population diversity for searching the entire solution space. The other is to ensure quick convergence to the optimal solution set. In this paper, we propose a novel two-archive strategy for evolutionary many-objective optimization algorithm. The uniform archive strategy, based on reference points, is used to keep population diversity in the evolutionary process, and to ensure that an evolutionary algorithm is able to search the entire solution space. The single elite archive strategy is used to ensure that individuals with the best single objective value are able to evolve into the next generation and have more opportunities to generate offspring. This strategy aims to improve the convergence rate. Then this novel two-archive strategy is applied to improving the Non-dominated Sorting Genetic Algorithm (NSGA-III). Simulation experiments are conducted on benchmark test sets and experimental results show that our proposed algorithm with the two-archive strategy has a better performance than other state-of-art algorithms.     

改进灰狼优化算法求解模糊车间调度问题

模糊车间调度问题是复杂调度的经典体现,针对此问题设计优秀的调度方案能提高生产效率。目前对于模糊车间调度问题的研究主要集中在单目标上,因此提出一种改进的灰狼优化算法（improved grey wolf optimization,IGWO）求解以最小化模糊完成时间和最小化模糊机器总负载的双目标模糊柔性作业车间调度问题。该算法首先采用双层编码将IGWO离散化,设计一种基于HV贡献度的策略提高种群多样性;然后使用强化学习方法确定全局和局部的搜索参数,改进两种交叉算子协助个体在不同更新模式下的进化;接着使用两级变邻域和四种替换策略提高局部搜索能力;最后在多个测例上进行多组实验分析验证改进策略的有效性。在多数测例上,IGWO的性能要优于对比算法,具有良好的收敛性和分布性。     

A self-organizing random immigrants genetic algorithm for dynamic optimization problems

In this paper a genetic algorithm is proposed where the worst individual and individuals with indices close to its index are replaced in every generation by randomly generated individuals for dynamic optimization problems. In the proposed genetic algorithm, the replacement of an individual can affect other individuals in a chain reaction. The new individuals are preserved in a subpopulation which is defined by the number of individuals created in the current chain reaction. If the values of fitness are similar, as is the case with small diversity, one single replacement can affect a large number of individuals in the population. This simple approach can take the system to a self-organizing behavior, which can be useful to control the diversity level of the population and hence allows the genetic algorithm to escape from local optima once the problem changes due to the dynamics.     

基于遗传算法的弹性TSP研究

文中针对遗传算法求解TSP问题，探讨了使用弹性边控制策略来保证群体的多样性，并结合TSP问题的特点，定义了一种新的衡量群体的多样性的方法。通过对算法的分析和测试表明，该算法的改进是有效的。     

An efficient memetic algorithm for total weighted tardiness minimization in a single machine with setups

The single machine scheduling problem with sequence-dependent setup times with the objective of minimizing the total weighted tardiness is a challenging problem due to its complexity, and has a huge number of applications in real production environments. In this paper, we propose a memetic algorithm that combines and extends several ideas from the literature, including a crossover operator that respects both the absolute and relative position of the tasks, a replacement strategy that improves the diversity of the population, and an effective but computationally expensive neighborhood structure. We propose a new decomposition of this neighborhood that can be used by a variable neighborhood descent framework, and also some speed-up methods for evaluating the neighbors. In this way we can obtain competitive running times. We conduct an experimental study to analyze the proposed algorithm and prove that it is significantly better than the state-of-the-art in standard benchmarks.     

高维多目标头脑风暴优化算法

多目标优化的两个核心指标是收敛性和多样性,而对二者加以优化和权衡是多目标进化算法的关键.头脑风暴优化算法作为一种新型的群体智能优化算法,一经提出便引起了众多研究者的关注.本文在对现有的多目标头脑风暴优化算法研究的基础上,通过对决策变量进行分析,围绕收敛性和多样性分别进行优化,在对收敛性优化时通过分解策略增加选择压力,而在对多样性优化时以参考点更新种群增加多样性,最终扩展并提出了高维多目标头脑风暴优化算法.此外,本文提出一种以角点为聚类中心的自适应聚类方式,明确个体的导向,提高种群的扩展性.与现有的几种效果较好的多目标进化算法进行比较,大量的仿真结果表明了本文的算法具有优秀的性能.     

动态搜索和协同进化的鲸鱼优化算法

针对基本鲸鱼优化算法寻优精度低、收敛速度慢及容易陷入局部最优等缺陷,提出了一种动态搜索和协同进化的鲸鱼优化算法。首先,通过等价替换和Faure序列提高初始解的质量;其次,通过对种群进行分工,提高种群多样性并增强算法跳出局部最优解的能力;最后,根据种群进化信息动态调整搜索策略,从而提高算法的收敛速度和寻优精度。仿真实验结果表明,提出的改进算法相比基本鲸鱼优化算法和部分改进算法具有较好的寻优性能。     

一种基于自主计算的双种群遗传算法

针对多种群遗传算法在处理复杂多峰函数优化问题时效率低下、容易早熟收敛等缺点,提出一种基于自主计算的双种群遗传算法。双种群包括一个主种群和一个协助种群,协助种群通过系统的内、外监视器动态地向主种群传递优良个体和调整迁移间隔,以帮助主种群进化,并改进适应度函数防止迁移者过早死亡以保持种群多样性。实验结果证明,该算法优于标准遗传算法和双种群的多种群遗传算法。     

粒子置换的双种群综合学习PSO算法

针对粒子群算法(PSO)种群多样性低和易于陷入局部最优等问题,提出一种粒子置换的双种群综合学习PSO算法(PP-CLPSO).根据PSO算法的收敛特性和Logistic映射的混沌思想,设计并行进化的PSO种群和混沌化种群,结合粒子编号机制,形成双种群系统中粒子的同号结构和同位结构,其中粒子的惯性权重根据适应度值自适应调...     

基于指标和自适应边界选择的高维多目标优化算法

多目标优化算法的主要目标是实现好的多样性和收敛性.传统的高维多目标优化算法,当目标维数增加时,选择方式难以平衡种群的收敛性与多样性.对此,提出一个基于指标和自适应边界选择的高维多目标优化算法.在环境选择中,首先计算种群中两两个体的指标Iε(x,y)作为第一选择标准;其次,提出一种自适应边界选择策略,利用种群进化信息对超...     

Evolutionary algorithms with dynamic population size and localexploration for multiobjective optimization

Evolutionary algorithms have been recognized to be well suited for multiobjective optimization. These methods, however, need to "guess" for an optimal constant population size in order to discover the usually sophisticated tradeoff surface. This paper addresses the issue by presenting a novel incrementing multiobjective evolutionary algorithm (IMOEA) with dynamic population size that is computed adaptively according to the online discovered tradeoff surface and its desired population distribution density. It incorporates the method of fuzzy boundary local perturbation with interactive local fine tuning for broader neighborhood exploration. This achieves better convergence as well as discovering any gaps or missing tradeoff regions at each generation. Other advanced features include a proposed preserved strategy to ensure better stability and diversity of the Pareto front and a convergence representation based on the concept of online population domination to provide useful information. Extensive simulations are performed on two benchmark and one practical engineering design problems     

多样性保持的和声搜索算法及其TSP求解

为了改善和声记忆库群体多样性, 提高算法的全局寻优能力, 在度量群体多样性指标的基础上, 从参数动态调整方法、和声记忆库更新策略两个方面对基本和声搜索算法进行了改进, 提出了多样性保持的和声搜索算法, 并将该算法应用于TSP的求解。结合TSP问题特点, 设计了基于交换和插入算子的和声微调方法。实例优化结果表明, 改进后的算法不容易陷入局部最优, 优化性能显著提高。     

融合学习策略和邻域搜索的飞蛾火焰算法

为进一步降低基本飞蛾火焰算法陷入局部最优的概率并提高种群多样性,提出一种融合学习策略和邻域搜索的飞蛾火焰算法。将拟反向学习策略嵌入到火焰更新过程,有助于火焰从局部最优中跳出,并且提供了更高的机会接近问题的未知最优解。对飞蛾种群基于适应度值分群,其中一个群采用排序配对学习策略以实现个体间的信息交流,另一个群采用邻域搜索策略以增加种群多样性,这种并行计算能更快地提升整个种群的质量。选取CEC2017测试函数进行数值实验,测试结果和统计分析表明了所提算法具有更高的求解精度和稳定性。将所提算法用于求解OR-Library中的标准实例,结果验证了所提算法对作业车间调度问题是有效的。     

基于多样性反馈的自适应粒子群优化算法

为了进一步提高种群多样性在粒子群优化执行中的效率,提出一种基于多样性反馈的自适应粒子群优化算法(APSO)。APSO采用一种新的种群多样性评价策略,使惯性权值在搜索过程中随多样性自适应性地调整,从而均衡算法的勘探和开发过程。此外,最优粒子采用精英学习策略跳出局部最优区域,从而在保证算法收敛速度的同时能够自适应地调整搜索方向,提高解的精确度。通过一组典型测试函数的仿真结果,验证了APSO的有效性。     

Optimizing sequential diagnostic strategy for large-scale engineering systems using a quantum-inspired genetic algorithm: A comparative study

Sequential diagnostic strategy (SDS) is widely used in engineering systems for fault isolation. In order to find source faults efficiently, the optimized SDS selects the most useful tests and schedules them in an optimized sequence. In this paper, a multiple-objective mathematical model for SDS optimization problem in large-scale engineering system is established, and correspondingly, a quantum-inspired genetic algorithm (QGA) specially targeted at this SDS optimization problem is developed. This QGA algorithm uses the form of probability amplitude of quantum bit to encode each possible diagnostic strategy extracted from fault-test dependency matrix, and then goes through evolutionary process to find the optimal strategy considering dual objectives of the expected testing cost and the number of contributing tests. Crossover and mutation operations are combined with quantum encoding in this algorithm to expand the diversity of population within a small population size and to increase the possibility of obtaining the global optimum. A case of control moment gyro system from real practice is used to verify the effectiveness of this algorithm, and a comparative study with two conventional intelligent optimization algorithms proposed for this problem, PSO and genetic algorithm, are presented to reveal its advantages.     

基于交叉变异策略的双种群差分进化算法

为加强差分进化算法的全局搜索能力,提出了一种基于交叉变异策略的双种群差分进化算法（CMDPDE）。CMDPDE中,两个种群分别采用大小不同的缩放因子和交叉因子,在每代进化完毕后,对其中缩放因子和交叉因子较小的种群执行交叉或变异策略来寻找更优的个体,同时两个种群之间每10代进行一次信息交流。这种方式与单种群差分进化算法相比,可以通过双种群和交叉变异策略来增加解的多样性,使算法能在更大的范围内寻优。6个Benchmark函数的实验结果证明CMDPDE具有较好的寻优能力。     

基于谱聚类的Web多级缓存替换策略

服务器缓存性能的核心是缓存替换策略,缓存替换策略直接影响缓存的命中率, Web缓存可以解决网络拥塞和用户访问延迟问题,提高服务器的性能.传统缓存替换算法的命中率往往不高,为此文中提出了一种基于谱聚类的多级缓存替换策略.该策略利用循环滑动窗口机制提取日志文件的多项时序特征和访问属性,通过谱聚类对过滤后的数据集进行聚类分析从而得到访问预测结果.多级缓存替换策略综合考虑了缓存对象的局部频率、全局频率以及资源大小能更好地对低价值资源进行剔除,同时对高价值资源进行保留.通过与传统替换算法LRU、LFU、RC、FIFO进行实验对比,实验结果表明本文将谱聚类和多级缓存替换策略进行结合有效地提高了缓存请求命中率和字节命中率.     

基于种群关联策略和强化解集准则的高维多目标进化算法

一般的高维多目标进化算法无法有效处理不同类型的Pareto前沿.针对这一情况,提出一种基于种群关联策略和强化解集准则的高维多目标进化算法(many-objective evolutionary algorithm based on population association strategy and enhanced solution set criterion, MaOEA/PAS-ESC).该算法在环境选择中采用种群关联策略(population association strategy, PAS)和强化解集准则(enhanced solution set criterion, ESC)协同指导种群进化. PAS利用解与参考向量的角度和欧氏距离以及种群中解之间的距离构建角度与距离联合函数(joint function of angle and distance, JFAD),选择多样性良好的解,然后ESC利用参考点与种群间的联系组成适应度函数,选择收敛性良好的解,以共同达到有效平衡多样性和收敛性的目的.实验结果表明,采用MaOEA/PAS-ESC处理高维多目标优化问题具有更强的竞...     

多群多策略差分大规模多目标优化算法

针对差分进化算法在解决大规模多目标优化问题时,出现优化后期多样性不足、收敛速度慢等问题,提出一种多群多策略差分大规模多目标优化算法.根据个体特性不同,将种群分为3个等级不同的子群,利用多群策略的优势维持种群多样性.为减少种群陷入局部最优的概率,在不同等级的子群中引入多个变异策略以较好地平衡子群个体的多样性和收敛性.为保证不同子群间信息得到有效交换,根据3个子群的进化状态确定重新分群时机,既保证个体在本群内得到充分进化,又保证个体在一定的条件下进行信息交换.为利用更多的信息生成优秀的子代,将更新后的子群与其父代子群合并,选出下一代子群.为验证所提出算法的有效性,在一组大规模基准测试问题上评估算法的性能,实验结果表明,所提出算法在两个常用测试指标IGD和HV上明显优于其他对比算法.