基于改进的选择算子和交叉算子的遗传算法

为了有效解决遗传算法中收敛速度与局部最优解的矛盾,文中提出了一种具有改进的选择算子和改进的交叉算子的遗传算法。使用文中改进的选择算子,能够增加算法收敛于全局最优解的概率,从而不容易陷入局部最优,也就增加了找到最优解的概率,使用文中改进的交叉算子可以加快算法的收敛速度,从而缩短寻找最优解的时间。实验证明,这两种改进算子的结合能以较快速度收敛于全局最优解,因此能很好地解决遗传算法中收敛速度与局部最优解之间的矛盾。     

基于改进的选择算子和交叉算子的遗传算法

为了有效解决遗传算法中收敛速度与局部最优解的矛盾,文中提出了一种具有改进的选择算子和改进的交叉算子的遗传算法。使用文中改进的选择算子,能够增加算法收敛于全局最优解的概率,从而不容易陷入局部最优,也就增加了找到最优解的概率,使用文中改进的交叉算子可以加快算法的收敛速度,从而缩短寻找最优解的时间。实验证明,这两种改进算子的结合能以较快速度收敛于全局最优解,因此能很好地解决遗传算法中收敛速度与局部最优解之间的矛盾。     

遗传算法的改进与应用

遗传算法是一种借鉴生物界自然选择和自然遗传机制的随机搜索算法,它与传统的算法不同。大多数古典的优化算法是基于一个单一的度量函数(评估函数)的梯度或较高次统计,以产生一个确定性的试验解序列;遗传算法不依赖于梯度信息,而是通过模拟自然进化过程来搜索最优解。该文针对传统遗传算法的缺陷,提出了一些新的改进思路,即从搜索技术和遗传算子等的角度来改进遗传算法。     

遗传算子的分析

阐述了遗传算法的特点，分析了遗传算法中选择算子、交叉算子和变异算子的特性，讨论了不同遗传算子对算法最优结果的获得所起的作用，提出了改善算法性能的措施，并设计了切实可行的选择算子、交叉算子和变异算子。模拟结果表明，遗传算法能在较短的时间内提供优化解，为解决复杂的优化问题提供了可行方案。     

多点随机搜索算法估计反应动力学参数

提出一种多点随机搜索算法，一方面它汲取随机搜索算法的优点以克服陷人局部最优点；另一方面它通过判断搜索过程目标函数变化趋势，从而能在响应曲面的下降方向上前进，加快寻优进程。与遗传算法相比较，多点随机搜索算法能以更快的速度找到全局最优解；与梯度下降算法相比较，它能以更高的概率找到全局最优解。本文将多点随机搜索算法应用于2-氯苯酚在超临界水中氧化反应动力学参数的估算，获得动力学模型对实验数据拟合的相对误差绝对值之和比文献报道降低了14．1％。     

基于工件位置交叉算子的车间作业调度算法

交叉算子是遗传算法中最主要的遗传算子,对种群的搜索性能起着重要的作用。基于操作编码的遗传算法多采用两点交叉算子,研究发现这种交叉算子收敛速度慢,容易陷入局部最优解,为此设计了一种基于工件位置的交叉算子,通过试验仿真验证了该算子在收敛速度和求全局最优解上有显著优势。     

遗传算子的分析

阐述了遗传算法的特点,分析了遗传算法中选择算子、交叉算子和变异算子的特性,讨论了不同遗传算子对算法最优结果的获得所起的作用,提出了改善算法性能的措施,并设计了切实可行的选择算子、交叉算子和变异算子。模拟结果表明,遗传算法能在较短的时间内提供优化解,为解决复杂的优化问题提供了可行方案。     

基于改进遗传算法的舰船路径规划

遗传算法在解决非线性问题上具有良好的适用性,但是也存在着收敛性慢和局部最优解的缺陷,并且在实际应用中缺乏特定知识的利用.针对舰船路径规划的特点,对标准遗传算法进行了改进和优化,采用基于坐标的一维编码方式,设计了插入算子、删除算子、平滑算子和扰动算子,提高了进化效率.计算机仿真结果表明,该算法在收敛速度和输出全局最优解的概率相对于标准遗传算法都有了显著提高.     

基于自适应遗传算法的软件测试用例自动生成

在软件测试中,测试成功的关键是快速、高效的生成测试用例.遗传算法是一种通过模拟自然界生物进化过程搜寻最优解的一种算法,算法通过选择、交叉和变异操作引导算法搜索方向,逐步接近全局最优解.传统遗传算法由于具有较好的全局搜索能力,因此被很多科研人员应用于测试用例生成.但遗传算法的固有缺陷"早熟收敛",容易导致算法收敛于局部最优.针对这种情况,提出一种自适应遗传算法,该算法交叉算子和变异算子可根据程序变化自动调整,随后,将改进后的算法应用于一程序的测试用例生成中.测试结果表明该算法在测试用例生成的效率和效果方面优于传统搜索算法和普通改进算法.     

基于异位交叉的遗传算法的研究

针对目前遗传算法搜索速度较慢的问题，对提高遗传算法收敛速度的不同方法进行了分析。提出一种加快收敛速度的异位交叉算子，并给出算法仿其实验。仿真结果表明，这种交叉算子可比一般的对等位交叉算子更有效地提高收敛速度，且不易陷入局部最优解。具有实现简单、易于应用及鲁捧性强的特点。     

Multi-operator based evolutionary algorithms for solving constrained optimization problems

Over the last two decades, many sophisticated evolutionary algorithms have been introduced for solving constrained optimization problems. Due to the variability of characteristics in different COPs, no single algorithm performs consistently over a range of problems. In this paper, for a better coverage of the problem characteristics, we introduce an algorithm framework that uses multiple search operators in each generation. The appropriate mix of the search operators, for any given problem, is determined adaptively. The framework is tested by implementing two different algorithms. The performance of the algorithms is judged by solving 60 test instances taken from two constrained optimization benchmark sets from specialized literature. The first algorithm, which is a multi-operator based genetic algorithm (GA), shows a significant improvement over different versions of GA (each with a single one of these operators). The second algorithm, using differential evolution (DE), also confirms the benefit of the multi-operator algorithm by providing better and consistent solutions. The overall results demonstrated that both GA and DE based algorithms show competitive, if not better, performance as compared to the state of the art algorithms.     

GENETIC ALGORITHM APPROACH TO A LUMBER CUTTING OPTIMIZATION PROBLEM

Genetic algorithms are a technique for search and optimization based on the Darwinian principle of natural selection. They are iterative search procedures that maintain a population of candidate solutions. The best or most fit solutions in that population are then used as the basis for the next generation of solutions. The next generation is formed using the genetic operators reproduction, crossover, and mutation. Genetic algorithms have been successfully applied to engineering search and optimization problems. This paper presents a discussion of the basic theory of genetic algorithms and presents a genetic algorithm solution of a lumber cutting optimization problem. Dimensional lumber is assigned a grade that represents its physical properties. A grade is assigned to every board segment of a specific length. The board is then cut in various locations in order to maximize its value, A genetic algorithm was used to determine the cutting patterns that would maximize the board value.     

一种基于知识进化的多层次结构产品整体方案创新设计方法

研究并提出了一种基于知识进化的多层次结构产品整体方案创新设计系统模型,该模型根据机械产品都具有多层次结构的特点,通过把机械方案设计过程看作是一个状态空间的求解问题,用基因算法（DGA）从整体上控制其搜索过程,构建了新的多层次基因编码体系。为了适应新的编码体系重新构建了交叉和变异等基因操作,并利用复制、交换和变异等操作进行一次次迭代,最终自动生成一组最优的设计方案。该系统经过实例验证具有很高的有效性、准确性和实用性。     

Structured population genetic algorithms: a literature survey

The Genetic Algorithm (GA) has been one of the most studied topics in evolutionary algorithm literature. Mimicking natural processes of inheritance, mutation, natural selection and genetic operators, GAs have been successful in solving various optimization problems. However, standard GA is often criticized as being too biased in candidate solutions due to genetic drift in search. As a result, GAs sometimes converge on premature solutions. In this paper, we survey the major advances in GA, particularly in relation to the class of structured population GAs, where better exploration and exploitation of the search space is accomplished by controlling interactions among individuals in the population pool. They can be classified as spatial segregation, spatial distance and heterogeneous population. Additionally, secondary factors such as aging, social behaviour, and so forth further guide and shape the reproduction process. Restricting randomness in reproduction has been seen to have positive effects on GAs. It is our hope that by reviewing the many existing algorithms, we shall see even better algorithms being developed.     

Dynamic and heuristic fuzzy connectives-based crossover operators for controlling the diversity and convergence of real-coded genetic algorithms

Genetic algorithms are adaptive methods which may be used as approximation heuristic for search and optimization problems. Genetic algorithms process a population of search space solutions with three operations: selection, crossover, and mutation. A great problem in the use of genetic algorithms is the premature convergence, a premature stagnation of the search caused by the lack of diversity in the population and a disproportionate relationship between exploitation and exploration. The crossover operator is considered one of the most determinant elements for solving this problem. In this article we present two types of crossover operators based on fuzzy connectives for real-coded genetic algorithms. The first type is designed to keep a suitable sequence between the exploration and the exploitation along the genetic algorithm's run, the dynamic fuzzy connectives-based crossover operators, the second, for generating offspring near to the best parents in order to offer diversity or convergence in a profitable way, the heuristic fuzzy connectives-based crossover operators. We combine both crossover operators for designing dynamic heuristic fuzzy connectives-based crossover operators that show a robust behavior. © 1996 John Wiley & Sons, Inc.     

含忽略工序和不相关机的混合流水车间调度

研究从炼钢等生产过程提炼出的含忽略工序和不相关并行机的混合流水车间调度问题,以最小化最大完工时间为目标,建立整数规划模型,并提出结合全局搜索、自适应遗传算法和候鸟优化的遗传候鸟优化算法以求解该模型。在算法中采用与处理时间相关的全局搜索和随机程序以获得初始种群,提出自适应交叉和变异操作改进遗传算法解,在迭代进程中,引入基于工件、机器和工序位3种邻域搜索结构的候鸟优化算法更新最佳解。仿真实验中将遗传候鸟优化算法的实验结果与几种启发式算法进行对比,证明了模型和算法的有效性。     

基于改进遗传算法的多示例神经网络优化

多示例神经网络是一类用于求解多示例学习问题的神经网络,但由于其中有不可微函数,使用反向传播训练方法时需要采用近似方法,因此多示例神经网络的预测准确性不高。〖BP）〗为了提高预测准确性,构造了一类优化多示例神经网络参数的改进遗传算法, 借助基于反向传播训练的局部搜索算子、排挤操作和适应性操作概率计算方式来提高收敛速度和防止早熟收敛。通过公认的数据集上实验结果的分析和对比,证实了这个改进的遗传算法能够明显地提高多示例神经网络的预测准确性,同时还具有比其他算法更快的收敛速度。     

Genetic algorithms and neural networks: optimizing connections and connectivity

Genetic algorithms are a robust adaptive optimization method based on biological principles. A population of strings representing possible problem solutions is maintained. Search proceeds by recombining strings in the population. The theoretical foundations of genetic algorithms are based on the notion that selective reproduction and recombination of binary strings changes the sampling rate of hyperplanes in the search space so as to reflect the average fitness of strings that reside in any particular hyperplane. Thus, genetic algorithms need not search along the contours of the function being optimized and tend not to become trapped in local minima. This paper is an overview of several different experiments applying genetic algorithms to neural network problems. These problems include

1. (1) optimizing the weighted connections in feed-forward neural networks using both binary and real-valued representations, and

2. (2) using a genetic algorithm to discover novel architectures in the form of connectivity patterns for neural networks that learn using error propagation.

Future applications in neural network optimization in which genetic algorithm can perhaps play a significant role are also presented.     

A Genetic Algorithm for Multiobjective Robust Design

The goal of robust design is to develop stable products that exhibit minimum sensitivity to uncontrollable variations. The main drawback of many quality engineering approaches, including Taguchi's ideology, is that they cannot efficiently handle presence of several often conflicting objectives and constraints that occur in various design environments.Classical vector optimization and multiobjective genetic algorithms offer numerous techniques for simultaneous optimization of multiple responses, but they have not addressed the central quality control activities of tolerance design and parameter optimization. Due to their ability to search populations of candidate designs in parallel without assumptions of continuity, unimodality or convexity of underlying objectives, genetic algorithms are an especially viable tool for off-line quality control.In this paper we introduce a new methodology which integrates key concepts from diverse fields of robust design, multiobjective optimization and genetic algorithms. The genetic algorithm developed in this work applies natural genetic operators of reproduction, crossover and mutation to evolve populations of hyper-rectangular design regions while simultaneously reducing the sensitivity of the generated designs to uncontrollable variations. The improvement in quality of successive generations of designs is achieved by conducting orthogonal array experiments as to increase the average signal-to-noise ratio of a pool of candidate designs from one generation to the next.     

文件传输的遗传算法优化研究

给出了文件传输问题的边着色模型。遗传算法是一种借鉴生物界自然选择和进化机制发展起来的高度并行的、随机搜索算法，具有自适应性。为了求解文件传输问题，文章在引入一种新的自适应性的交换概率和变异概率的基础士，提出了一种面向求解文件传输问题的遗传算法。提供了遗传算法的结构并讨论了遗传算子。本文给出了一个例子说明算法的收敛性和收敛效率，仿真结果表明了算法的有效性。