二维抛物型方程参数反演模型的拟牛顿法

讨论了二维变系数抛物型方程的参数识别反问题,将其归为最优化问题,指定待定参数的函数类形式,用拟牛顿法来演化待求参数的最优估计值,并将该方法运用于线性扩散方程和具有分段函数系数的二维抛物型方程的参数识别反问题的数值模拟中,数值结果表明拟牛顿法（BFGS）解决此类问题是有效的和可行的。     

演化算法求解光纤光栅反问题的研究进展

对演化算法求解光纤光栅反问题的研究进行了综述。光纤光栅的反问题即从给定的光纤光栅反射谱（或透射谱）,重构得到光栅的长度、周期、折射率调制深度等参数,以及应力、温度分布等,是在传感和通讯领域都会遇到的一类重要问题。演化算法由于具有计算简单、普适性强、潜在的并行性等优点,近年来被广泛用于求解光纤光栅的反问题,其中主要有遗传算法、模拟退火算法、粒子群优化算法等。文章分析了演化算法求解光纤光栅反问题的优势和不足,并对其研究前景进行了展望。     

科恩-沈方程与含时科恩-沈方程的一个自适应有限元数值方法

在材料分析、纳米光学等研究中,高质量数值模拟多体系统电子密度的随时间演化是一类重要研究内容.演化中产生的时间依赖偶极子等物理量,是更进一步研究的基础.此类数值模拟分为两个步骤.即多体系统的基态求解、及以基态为初值的系统的动态演化模拟.这两个步骤可以分别通过数值求解科恩-沈(Kohn-Sham)方程及含时科恩-沈(time-dependent Kohn-Sham)方程实现.本文中,我们提出一类基于有限元方法的数值求解框架,为这两个步骤提供一个统一的模拟实现.在基态求解中,我们利用一类自洽场迭代对方程进行线性化,采用局部最优块预处理共轭梯度法求解导出的广义特征值问题,并设计了一个基于多重网格方法的预优对求解进行有效加速.在动态演化模拟中,针对方程的结构,我们提出了一个基于隐式中点公式的数值方法,利用预估-校正方法对方程进行线性化处理,并设计了一个针对复值线性系统的代数多重网格求解器用于加速时间推进.特别地,我们基于提出的数值方法,分别针对科恩-沈及含时科恩-沈方程导出了残量型后验误差估计子,并实现了基于局部加密的网格自适应方法,用于进一步改善数值模拟效率.数值解展示了方法的有效性.     

区间粒子算法与线源反问题求解

目前国内外对线源反问题数值求解尚没有一种成熟有效的算法。本文在研究区间搜索算法基础上,提出了一种新的求解算法—区间粒子算法(Range Particle Algorithm)来求解线源反问题。首先简要介绍了线源反问题的求解特点,并根据线源方程建立了反问题求解的目标函数;其次基于该目标函数,设计了区间粒子算法来求解,探讨了算法实现的基本步骤和参数调整问题;最后通过模拟数据和实测数据分别检验了该算法求解的效果,结果表明区间粒子算法求解精度高、收敛速度快和计算稳定,在线源反问题数值求解中是适用的。     

求解分式规划的社会认知算法

对分式规划问题进行了研究,由于此类问题目标函数为分式,传统的梯度类算法求解此类问题很困难.结合近年来出现的一类新的智能算法——社会认知算法,给出了该类问题的一种有效求解方法.该算法是基于社会认知理论,通过一系列的学习代理来模拟人类的社会性以及智能性从而完成对目标的优化.该算法对目标函数的解析性质没有要求,具有易实现、高效以及普适性.数值结果表明了该方法在求解分式规划问题中的有效性.     

改进约束人工蜂群算法及金融应用

为了有效求解约束优化问题，提出一种改进人工蜂群算法。该算法引入Pareto支配准则提高算法探索能力，避免算法早熟。在雇佣蜂阶段，通过识别种群当前状态自适应选取搜索方程与约束处理策略，引导种群快速进入可行区域。在跟随蜂阶段，利用全局最优解引导种群进行搜索，提高算法开发能力。通过对CEC 2006中20个测试函数实验结果分析表明，该算法能够有效求解约束优化问题。进而，将该算法应用于求解投资组合优化问题，通过数值实验说明该算法是求解投资组合优化问题的有效算法，可以用于求解此类金融问题。     

基于进化策略的线性变分不等式求解算法

基于在求解变分不等式过程中存在着传统数字计算机的迭代算法很难满足并行性要求的问题,提出了求解一类线性变分不等式问题的进化策略算法.将进化策略算法用于求解线性变分不等式的数值方法,充分发挥了进化策略算法的全局收敛和并行搜索的特性,满足了工程技术中并行求解变分不等式问题的要求.数值计算结果表明,该算法收敛速度快、精度高,稳定性好,是一种解决线性变分不等式问题的有效方法.     

改进的免疫优化算法对动态约束多目标问题的应用

基于进化理论的动态多目标优化算法极易陷入局部最优,跟踪动态Pareto有效面的速度及效果较差。基于免疫系统机理提出一种改进的免疫优化算法(DMIOA)用于动态约束多目标问题求解。算法通过抗体浓度及其支配度设计抗体与抗原亲和力,随机约束选择算子提高算法约束处理能力,环境识别算子自适应判断环境变化,根据识别结果以不同的方式产生新环境的初始抗体群。数值实验中,将DMIOA应用于两种动态标准测试问题及飞机减速器参数动态设计问题的求解,结果表明:DMIOA能快速跟踪动态Pareto有效面,且在各环境所获面分布均匀,具有较好的实际问题求解能力。     

一类新的寻求全局最优解的填充函数

填充函数法是一种求解多变量、多极值函数全局最优化的有效方法,该方法最早由葛入溥在文献[1]中提出,这种方法的关键是构造填充函数.文中在无Lipschitz连续条件下,考虑用单参数填充函数求解无约束全局优化问题,给出了一类新的形式简单的单参数填充函数.容易证明该填充函数在参数充分小时就能保持其填充性质.根据这个填充函数还提出了一个求解无约束优化问题的填充函数算法,通过一些检验函数的数值运算结果验证了算法的可行性和有效性.     

一类布尔方程组的可满足性阈值研究*

以一类布尔方程组形式的NP问题可满足性阈值估计为研究目的,通过将高斯消去算法与摘叶算法相结合的方法给出了一种求解该问题的完全算法,并通过不同参数条件下对大量随机实例进行数值实验得到了原问题可满足性阈值的算法估计值。所得研究结果不仅首次给出了该问题的可满足性阈值估计,而且可以作为相关启发式完全算法的设计依据。     

Hybridizations of evolutionary algorithms with Large Neighborhood Search

Recent developments of evolutionary algorithms (EAs) for discrete optimization problems are often characterized by the hybridization of EAs with local search methods, in particular, with Large Neighborhood Search. In this survey, we consider some of the most promising directions of this kind of hybridization and provide examples in the context of well-known optimization problems. We distinguish different approaches by the algorithmic components in which they make use of Large Neighborhood Search: initialization, recombination and the local improvement stages of hybrid EAs.     

An adaptive optimization technique for dynamic environments

The use of evolutionary algorithms (EAs) is beneficial for addressing optimization problems in dynamic environments. The objective function for such problems changes continually; thus, the optimal solutions likewise change. Such dynamic changes pose challenges to EAs due to the poor adaptability of EAs once they have converged. However, appropriate preservation of a sufficient level of individual diversity may help to increase the adaptive search capability of EAs. This paper proposes an EA-based Adaptive Dynamic OPtimization Technique (ADOPT) for solving time-dependent optimization problems. The purpose of this approach is to identify the current optimal solution as well as a set of alternatives that is not only widespread in the decision space, but also performs well with respect to the objective function. The resultant solutions may then serve as a basis solution for the subsequent search while change is occurring. Thus, such an algorithm avoids the clustering of individuals in the same region as well as adapts to changing environments by exploiting diverse promising regions in the solution space. Application of the algorithm to a test problem and a groundwater contaminant source identification problem demonstrates the effectiveness of ADOPT to adaptively identify solutions in dynamic environments.     

Immigrant schemes for evolutionary algorithms in dynamic environments: Adapting the replacement rate

One approach for evolutionary algorithms (EAs) to address dynamic optimization problems (DOPs) is to maintain diversity of the population via introducing immigrants.So far all immigrant schemes developed for EAs have used fixed replacement rates.This paper examines the impact of the replacement rate on the performance of EAs with immigrant schemes in dynamic environments,and proposes a self-adaptive mechanism for EAs with immigrant schemes to address DOPs.Our experimental study showed that the new approach ...     

Estimation of distribution and differential evolution cooperation for large scale economic load dispatch optimization of power systems

Economic Load Dispatch (ELD) is an important and difficult optimization problem in power system planning. This article aims at addressing two practically important issues related to ELD optimization: (1) analyzing the ELD problem from the perspective of evolutionary optimization; (2) developing effective algorithms for ELD problems of large scale. The first issue is addressed by investigating the fitness landscape of ELD problems with the purpose of estimating the expected performance of different approaches. To address the second issue, a new algorithm named “Estimation of Distribution and Differential Evolution Cooperation” (ED-DE) is proposed, which is a serial hybrid of two effective evolutionary computation (EC) techniques: estimation of distribution and differential evolution. The advantages of ED-DE over the previous ELD optimization algorithms are experimentally testified on ELD problems with the number of generators scaling from 10 to 160. The best solution records of classical 13 and 40-generator ELD problems with valve points, and the best solution records of 10, 20, 40, 80 and 160-generator ELD problems with both valve points and multiple fuels are updated in this work. To further evaluate the efficiency and effectiveness of ED-DE, we also compare it with other state-of-the-art evolutionary algorithms (EAs) on typical function optimization tasks.     

Hybridization of evolutionary algorithms and local search by means of a clustering method.

This paper presents a hybrid evolutionary algorithm (EA) to solve nonlinear-regression problems. Although EAs have proven their ability to explore large search spaces, they are comparatively inefficient in fine tuning the solution. This drawback is usually avoided by means of local optimization algorithms that are applied to the individuals of the population. The algorithms that use local optimization procedures are usually called hybrid algorithms. On the other hand, it is well known that the clustering process enables the creation of groups (clusters) with mutually close points that hopefully correspond to relevant regions of attraction. Local-search procedures can then be started once in every such region. This paper proposes the combination of an EA, a clustering process, and a local-search procedure to the evolutionary design of product-units neural networks. In the methodology presented, only a few individuals are subject to local optimization. Moreover, the local optimization algorithm is only applied at specific stages of the evolutionary process. Our results show a favorable performance when the regression method proposed is compared to other standard methods.     

Evolutionary optimization for disaster relief operations: A survey

Effective planning and scheduling of relief operations play a key role in saving lives and reducing damage in disasters. These emergency operations involve a variety of challenging optimization problems, for which evolutionary computation methods are well suited. In this paper we survey the research advances in evolutionary algorithms (EAs) applied to disaster relief operations. The operational problems are classified into five typical categories, and representative works on EAs for solving the problems are summarized, in order to give readers a general overview of the state-of-the-arts and facilitate them to find suitable methods in practical applications. Several state-of-art methods are compared on a set of real-world emergency transportation problem instances, and some lessons are drawn from the experimental analysis. Finally, the strengths, limitations and future directions in the area are discussed.     

Simultaneous identification of damage and input dynamic force on the structure for structural health monitoring

In this paper, we present an approach for simultaneous identification of the system parameters and the input dynamic force time history. The inverse problem associated with the system identification is formulated as an optimization problem and is solved using a newly developed dynamic hybrid adaptive firefly algorithm (DHAFA). A modified version of Tikhonov regularization is employed while solving the inverse problem associated with the force identification in order to improve the quality of the solution. Numerical simulation studies have been carried out by solving three distinct numerical examples. Studies presented in this paper indicate that the proposed algorithm is effective in identifying the system parameters as well as the input dynamic force simultaneously and can be effectively used for structural health monitoring purposes. Convergence studies presented in this paper on the newly developed dynamic hybrid firefly algorithm indicate that the proposed algorithm has better convergence characteristics and can be effectively employed for solving complex nonlinear optimization problems associated with system identification.     

Empirical analysis of locality, heritability and heuristic bias in evolutionary algorithms: a case study for the multidimensional knapsack problem

Our main aim is to provide guidelines and practical help for the design of appropriate representations and operators for evolutionary algorithms (EAs). For this purpose, we propose techniques to obtain a better understanding of various effects in the interplay of the representation and the operators. We study six different representations and associated variation operators in the context of a steady-state evolutionary algorithm for the multidimensional knapsack problem. Four of them are indirect decoder-based techniques, and two are direct encodings combined with different initialization, repair, and local improvement strategies. The complex decoders and the local improvement and repair strategies make it practically impossible to completely analyze such EAs in a fully theoretical way. After comparing the general performance of the chosen EA variants for the multidimensional knapsack problem on two benchmark suites, we present a hands-on approach for empirically analyzing important aspects of initialization, mutation, and crossover in an isolated fashion. Static, inexpensive measurements based on randomly created solutions are performed in order to quantify and visualize specific properties with respect to heuristic bias, locality, and heritability. These tests shed light onto the complex behavior of such EAs and point out reasons for good or bad performance. In addition, the proposed measures are also examined during actual EA runs, which gives further insight into dynamic aspects of evolutionary search and verifies the validity of the isolated static measurements. All measurements are described in a general way, allowing for an easy adaption to other representations and problems.     

Hybrid adaptive evolutionary algorithm based on decomposition

The performance of search operators varies across the different stages of the search/optimization process of evolutionary algorithms (EAs). In general, a single search operator may not do well in all these stages when dealing with different optimization and search problems. To mitigate this, adaptive search operator schemes have been introduced. The idea is that when a search operator hits a difficult patch (under-performs) in the search space, the EA scheme “reacts” to that by potentially calling upon a different search operator. Hence, several multiple-search operator schemes have been proposed and employed within EA. In this paper, a hybrid adaptive evolutionary algorithm based on decomposition (HAEA/D) that employs four different crossover operators is suggested. Its performance has been evaluated on the well-known IEEE CEC’09 test instances. HAEA/D has generated promising results which compare well against several well-known algorithms including MOEA/D, on a number of metrics such as the inverted generational distance (IGD), the hyper-volume, the Gamma and Delta functions. These results are included and discussed in this paper.     

Evolutionary Algorithms for Minimax Problems in Robust Design

Many robust design problems can be described by minimax optimization problems. Classical techniques for solving these problems have typically been limited to a discrete form of the problem. More recently, evolutionary algorithms, particularly coevolutionary optimization techniques, have been applied to minimax problems. A new method of solving minimax optimization problems using evolutionary algorithms is proposed. The performance of this algorithm is shown to compare favorably with the existing methods on test problems. The performance of the algorithm is demonstrated on a robust pole placement problem and a ship engineering plant design problem.