用适应值激励机制提出遗传算法的效率

分析了传统遗传算法作为函数优化器在宏观进化机制上的局限性，讨论了群体的可进化性在函数优化中的作用。在此基础上提出在遗传算法中引入适应值激励机制，用它来动态地提高群体的可进化性。数值实验表明，带有适应值激励机制的改进遗传算法的搜索效率得到很大提高。     

多重群体遗传算法在多选择背包问题中的应用

为了解决多选择背包问题,引入了多重群体遗传算法作为求解方法,根据此问题的特点而制定了具体的杂交、变异方法,设计了遗传算法。在算法中以目标函数加惩罚函数为适应值评价函数,采用新陈代谢的选择策略,以更好地保持进化过程中的遗传多样性。实践表明,引入了多重群体遗传算法之后,求解此问题效率有明显的改善与提高。     

多重群体遗传算法在多选择背包问题中的应用

在解决多选择背包问题中，引入了多重群体遗传算法作为求解方法，根据此问题的特点，制定了具体的杂交、变异方法，设计了遗传算法。在算法中以目标函数加惩罚函数为适应值评价函数，采用新陈代谢的跨世代选择策略，以更好地保持进化过程中的遗传多样性。实践表明，引入了多重群体遗传算法之后，求解此问题效率有明显的改善与提高。     

基于适应值共享的多生境排挤遗传算法

针对优化多模函数时单纯使用共享和排挤机制的遗传算法所存在的缺陷,提出了基于适应值共享的多生境排挤遗传算法。基本思想是：按照共享的思想在对个体的适应值进行调整的同时,将排挤选择和相似个体中适应度最差个体被替换的策略分别应用于选择算子和群体的进化中。理论分析和数值实验表明,该算法很好地维持了种群多样性,对于各类多峰函数具有较强的搜索能力。     

基于进化个体适应值灰度的自适应交互式遗传算法

为将交互式遗传算法成功应用于复杂优化问题,有必要提高交互式遗传算法的性能。提出基于进化个体适应值灰度的交互式遗传算法,该算法采用灰度衡量进化个体的适应值评价不确定性;通过适应值区间的分析,提取反映进化种群分布的信息;基于此,给出了进化个体的交叉和变异概率。将该算法应用于服装进化设计系统,结果表明该算法在每代可以获取更多的满意解。     

自适应遗传算法

在遗传算法中约束条件贯穿于遗传运算的始终，这样必定影响运算效率。因为随着进化过程的进行，适应度较低的一些个体逐渐被淘汰，而适应度较高的个体越来越多，且都集中在最优点附近。基于遗传算法这种优胜劣汰的进化思想，该文提出一种改进的遗传算法——自适应遗传算法。其主要思想是在群体进化若干代后，将弱解空间删除，在以后的进化进程中以同样的群体大小只在强解空间进行群体的繁殖，则可加大强解空间的个体密度，提高解的精度，这样有助于性能优良的个体的产生，并且有可能缩短群体进化过程。将这种自适应遗传算法用于复杂函数的优化，算例结果表明该方法是有效和可靠的。     

包含交叉和变异操作的交互式遗传算法

传统交互式遗传算法在优化隐式性能指标时会使用户产生疲劳,影响优化质量与优化效率。为此,提出一种改进的交互式遗传算法。采用二元排序确定适应值评价的不确定度,根据评价序列的最大信息差异计算种群的收敛率,通过收敛率衡量种群进化状态,基于适应值不确定度和种群收敛率设计自适应交叉算子和变异算子,给出交叉概率和变异概率的计算公式,利用包含用户偏好信息的遗传策略引导进化,从而使进化结果更加客观。将该算法应用于服装进化设计系统,结果表明,与传统交互式遗传算法( T-IGA)相比,该算法可获取更多的满意解,提高了优化效率。     

元胞遗传算法的全局优化性能仿真分析

元胞遗传算法将遗传操作限制在邻域内进行,减缓了优势个体在群体中的扩散速度,具有更好的全局探索能力,在求解复杂优化问题中显示出优越性.与传统遗传算法对比,以选择压力作为分析手段,对元胞遗传算法进行定性分析.通过求解具有不同特征的函数,分析进化过程群体多样性变化.从进化过程群体分布图,直观得出元胞遗传算法具有较好的维持群体多样性能力;统计结果表明,元胞遗传算法能极大提高全局收敛率,并且求解稳定性更好.     

基于选择压力的全局优化元胞遗传算法分析

元胞遗传算法将遗传操作限制在邻域内进行,减缓了优势个体在群体中的扩散速度,具有更好的全局收敛性,在求解复杂优化问题中显示出优越性。与传统遗传算法对比,以选择压力作为分析手段,对元胞遗传算法进行定性分析。通过求解具有不同特征的函数,分析进化过程群体多样性变化,从进化过程群体分布图,直观得出元胞遗传算法具有较好的维持群体多样性能力;从计算的统计结果,得出元胞遗传算法能极大提高全局收敛率,并且求解稳定性更好。     

多模态函数优化的协同多群体遗传算法

讨论了多模态函数优化的遗传算法(GA)求解方法.分析了传统的基于排挤选择模型 和基于适应值共享的GA方法的特点和不足,应用模式理论研究了GA群体进化行为.提出了 宏观小生境思想和协同多群体GA的基本框架和详细算法流程,并给出了一种自动小生境半径 估计方法.采用典型函数进行了实例计算,结果表明了协同多群体GA的有效性.     

基于可进化性的自适应遗传算法

针对传统遗传算法容易陷入局部最优解的问题,提出一个基于可进化性的自适应遗传算法。将个体可进化性作为适应度函数的参数加入到随进化代数动态调整的非线性适应度函数中,动态调整整个种群的交叉与变异概率以逸出局部最优。实验结果表明,该算法可改善适应度不高但具有较好进化能力个体的生存概率,且提高了种群多样性与搜索效率。     

Genetic search: analysis using fitness moments

Genetic algorithms (GAs) are efficient and robust search methods that are being employed in a plethora of applications with extremely large search spaces. The directed search mechanism employed in GAs performs a simultaneous and balanced exploration of new regions in the search space and exploitation of already-discovered regions. This paper introduces the notion of fitness moments for analyzing the working of GAs. We show that the fitness moments in any generation may be predicted from those of the initial population. Since a knowledge of the fitness moments allows us to estimate the fitness distribution of strings, this approach provides for a method of characterizing the dynamics of GAs. In particular, the average fitness and fitness variance of the population in any generation may be predicted. We introduce the technique of fitness-based disruption of solutions for improving the performance of GAs. Using fitness moments, we demonstrate the advantages of using fitness-based disruption. We also present experimental results comparing the performance of a standard GA and two other GAs (the controlled disruption GA and the adaptive GA) that incorporate the principle of fitness-based disruption. The experimental evidence clearly demonstrates the power of fitness-based disruption     

A novel parallel hybrid intelligence optimization algorithm for a function approximation problem

A novel parallel hybrid intelligence optimization algorithm (PHIOA) is proposed based on combining the merits of particle swarm optimization with genetic algorithms. The PHIOA uses the ideas of selection, crossover and mutation from genetic algorithms (GAs) and the update velocity and situation of particle swarm optimization (PSO) under the independence of PSO and GAs. The proposed algorithm divides the individuals into two equation groups according to their fitness values. The subgroup of the top fitness values is evolved by GAs and the other subgroup is evolved by the PSO algorithm. The optimal number is selected as a global optimum at every circulation which shows better results than both PSO and GAs, then improves the overall performance of the algorithm. The PHIOA is used to optimize the structure and parameters of the fuzzy neural network. Finally, the experimental results have demonstrated the superiority of the proposed PHIOA to search the global optimal solution. The PHIOA can improve the error accuracy while speeding up the convergence process, and effectively avoid the premature convergence to compare with the existing methods.     

Periodical switching between related goals for improving evolvability to a fixed goal in multi-objective problems

Evolutionary computation plays a principal role in intelligent design automation. Evolutionary approaches have discovered novel and patentable designs. Nonetheless, evolutionary techniques may lead to designs that lack robustness. This critical issue is strongly connected to the concept of evolvability. In nature, highly evolvable species tend to be found in rapidly changing environments. Such species can be considered robust against environmental changes. Consequently, to create robust engineering designs it could be beneficial to use variable, rather than fixed, fitness criteria. In this paper, we study the performance of an evolutionary programming algorithm with periodical switching between goals, which are selected randomly from a set of related goals. It is shown by a dual-objective filter optimization example that altering goals may improve evolvability to a fixed goal by enhancing the dynamics of solution population, and guiding the search to areas where improved solutions are likely to be found. Our reference algorithm with a single goal is able to find solutions with competitive fitness, but these solutions are results of premature convergence, because they are poorly evolvable. By using the same algorithm with switching goals, we can extend the productive search length considerably; both the fitness and robustness of such designs are improved.     

Multi-objective genetic local search algorithm using Kohonen’s neural map

Genetic Algorithms (GAs) are population based global search methods that can escape from local optima traps and find the global optima regions. However, near the optimum set their intensification process is often inaccurate. This is because the search strategy of GAs is completely probabilistic. With a random search near the optimum sets, there is a small probability to improve current solution. Another drawback of the GAs is genetic drift. The GAs search process is a black box process and no one knows that which region is being searched by the algorithm and it is possible that GAs search only a small region in the feasible space. On the other hand, GAs usually do not use the existing information about the optimality regions in past iterations.In this paper, a new method called SOM-Based Multi-Objective GA (SBMOGA) is proposed to improve the genetic diversity. In SBMOGA, a grid of neurons use the concept of learning rule of Self-Organizing Map (SOM) supporting by Variable Neighborhood Search (VNS) learn from genetic algorithm improving both local and global search. SOM is a neural network which is capable of learning and can improve the efficiency of data processing algorithms. The VNS algorithm is developed to enhance the local search efficiency in the Evolutionary Algorithms (EAs). The SOM uses a multi-objective learning rule based-on Pareto dominance to train its neurons. The neurons gradually move toward better fitness areas in some trajectories in feasible space. The knowledge of optimum front in past generations is saved in form of trajectories. The final state of the neurons determines a set of new solutions that can be regarded as the probability density distribution function of the high fitness areas in the multi-objective space. The new set of solutions potentially can improve the GAs overall efficiency. In the last section of this paper, the applicability of the proposed algorithm is examined in developing optimal policies for a real world multi-objective multi-reservoir system which is a non-linear, non-convex, multi-objective optimization problem.     

Fitness landscapes and evolvability

In this paper, we develop techniques based on evolvability statistics of the fitness landscape surrounding sampled solutions. Averaging the measures over a sample of equal fitness solutions allows us to build up fitness evolvability portraits of the fitness landscape, which we show can be used to compare both the ruggedness and neutrality in a set of tunably rugged and tunably neutral landscapes. We further show that the techniques can be used with solution samples collected through both random sampling of the landscapes and online sampling during optimization. Finally, we apply the techniques to two real evolutionary electronics search spaces and highlight differences between the two search spaces, comparing with the time taken to find good solutions through search.     

旅行商问题的人工免疫算法

1 引言旅行商问题(TSP)是一个典型的有序组合优化问题,可以看成是许多领域内复杂工程优化问题的抽象形式。研究TSP问题的求解方法对解决复杂工程优化问题具有重要的参考价值。对于TSP问题,目前还没有完全有效的求解方法,但是,多年来人们一直在不停地探索。近年来,模拟自然界生物进化过程的求解TSP问题的方法不断见诸文献,但以基于     

Genetic algorithms based on an intelligent controller

Genetic algorithms (GAs) have been proven as robust search procedures. Numerous researchers have established the validity of GAs in optimization, machine learning and control applications. This paper presents a new intelligent control scheme using the robust sear h feature of GAs incorporating the basic idea of self-tuning regulators. The proposed controller utilized GAs to search for the changes of system parameters and to calculate the corresponding control law. The optimum parameters and control law are chosen based on the selection mechanism of GAs, which employs the square of the difference between the actual and the estimated outputs as the fitness function. The controller has an on-line parameters identification function and does not require prior knowledge or training data for learning.

The proposed intelligent controller is applied to the load frequency control of a power system to investigate the effectiveness from results obtained from computer simulations, the intelligent controller has been proven to provide good system characteristics.     

随机性对遗传算法演化机制的影响

就杂交过程随机性对遗传算法演化机制的影响进行了讨论,并提出随机性升序排列的三种演化算法。通过实验模拟,比较它们与随机性最高的ESGA算法对四个测试函数的寻优能力。由实验结果可知,随机性适中的TIGA算法对各测试函数的寻优能力最好。     

遗传算法求解多模态优化问题的动力性

多模态函数一般存在多个局部极值解, 局部极值解处适应值的大小很大程度上影响了它们被遗传算法搜索到的概率. 为了弄清楚这种影响机制, 通过分析基因池遗传算法的无限种群动力系统, 刻画了双峰函数局部极值解的适值差与系统不动点之间的解析关系, 进一步分析推广了理论结果的适用范围. 最后, 提出针对多模态优化问题的两阶段遗传算法, 给出了应用理论结果改善遗传搜索性能的范例, 实验结果表明该算法对多模态函数的搜索性能有明显改善, 从侧面证明了理论结果在实际应用中的正确性.