A new hybrid method using evolutionary algorithms to train Fuzzy Cognitive Maps

A novel hybrid method based on evolutionary computation techniques is presented in this paper for training Fuzzy Cognitive Maps. Fuzzy Cognitive Maps is a soft computing technique for modeling complex systems, which combines the synergistic theories of neural networks and fuzzy logic. The methodology of developing Fuzzy Cognitive Maps relies on human expert experience and knowledge, but still exhibits weaknesses in utilization of learning methods and algorithmic background. For this purpose, we investigate a coupling of differential evolution algorithm and unsupervised Hebbian learning algorithm, using both the global search capabilities of Evolutionary strategies and the effectiveness of the nonlinear Hebbian learning rule. The use of differential evolution algorithm is related to the concept of evolution of a number of individuals from generation to generation and that of nonlinear Hebbian rule to the concept of adaptation to the environment by learning. The hybrid algorithm is introduced, presented and applied successfully in real-world problems, from chemical industry and medicine. Experimental results suggest that the hybrid strategy is capable to train FCM effectively leading the system to desired states and determining an appropriate weight matrix for each specific problem.     

Disturbed Exploitation compact Differential Evolution for limited memory optimization problems

This paper proposes a novel and unconventional Memetic Computing approach for solving continuous optimization problems characterized by memory limitations. The proposed algorithm, unlike employing an explorative evolutionary framework and a set of local search algorithms, employs multiple exploitative search within the main framework and performs a multiple step global search by means of a randomized perturbation of the virtual population corresponding to a periodical randomization of the search for the exploitative operators. The proposed Memetic Computing approach is based on a populationless (compact) evolutionary framework which, instead of processing a population of solutions, handles its statistical model. This evolutionary framework is based on a Differential Evolution which cooperatively employs two exploitative search operators: the first is based on a standard Differential Evolution mutation and exponential crossover, and the second is the trigonometric mutation. These two search operators have an exploitative action on the algorithmic framework and thus contribute to the rapid convergence of the virtual population towards promising candidate solutions. The action of these search operators is counterbalanced by a periodical stochastic perturbation of the virtual population, which has the role of “disturbing” the excessively exploitative action of the framework and thus inhibits its premature convergence. The proposed algorithm, namely Disturbed Exploitation compact Differential Evolution, is a simple and memory-wise cheap structure that makes use of the Memetic Computing paradigm in order to solve complex optimization problems. The proposed approach has been tested on a set of various test problems and compared with state-of-the-art compact algorithms and with some modern population based meta-heuristics. Numerical results show that Disturbed Exploitation compact Differential Evolution significantly outperforms all the other compact algorithms present in literature and reaches a competitive performance with respect to modern population algorithms, including some memetic approaches and complex modern Differential Evolution based algorithms. In order to show the potential of the proposed approach in real-world applications, Disturbed Exploitation compact Differential Evolution has been implemented for performing the control of a space robot by simulating the implementation within the robot micro-controller. Numerical results show the superiority of the proposed algorithm with respect to other modern compact algorithms present in literature.     

神经网络与DE算法在自适应滤波中的应用

为了满足电流互感器自动测试系统中处理采集数据的需求,提出了一种基于神经网络与微分进化算法的自适应滤波器.在传统自适应滤波器结构中引入神经网络,提高了非线性处理能力;而微分进化算法则能保证全局最优解.试验表明,将改进后的滤波器应用于测试系统中具有较好的滤波效果,验证了该滤波方法应用于工业测控领域的正确性与可行性.     

基于差分演化的粒子群算法

粒子群优化算法是一种简单有效的随机全局优化算法.但粒子群优化算法有易陷入局部极值点,进化后期收敛速度慢,精度较差的缺点.为了改进粒子群优化算法,将差分演化算法融合到粒子群优化算法中,在算法中,将粒子每代的所有局部最优位置进行变异、杂交、选择操作,提出了基于差分演化的粒子群算法.使粒子群算法和差分演化的探测和开发能力得到有效利用与平衡,提高了求解进度和效率,并通过仿真验证算法的性能优于带线性递减权重的粒子群优化算法和差分演化算法.     

Differential evolution in constrained numerical optimization: An empirical study

Motivated by the recent success of diverse approaches based on differential evolution (DE) to solve constrained numerical optimization problems, in this paper, the performance of this novel evolutionary algorithm is evaluated. Three experiments are designed to study the behavior of different DE variants on a set of benchmark problems by using different performance measures proposed in the specialized literature. The first experiment analyzes the behavior of four DE variants in 24 test functions considering dimensionality and the type of constraints of the problem. The second experiment presents a more in-depth analysis on two DE variants by varying two parameters (the scale factor F and the population size NP), which control the convergence of the algorithm. From the results obtained, a simple but competitive combination of two DE variants is proposed and compared against state-of-the-art DE-based algorithms for constrained optimization in the third experiment. The study in this paper shows (1) important information about the behavior of DE in constrained search spaces and (2) the role of this knowledge in the correct combination of variants, based on their capabilities, to generate simple but competitive approaches.     

Simplifying the automatic design of a fuzzy logic controller using evolutionary programming

With the availability of a wide range of Evolutionary Algorithms such as Genetic Algorithms, Evolutionary Programming, Evolutionary Strategies and Differential Evolution, every conceivable aspect of the design of a fuzzy logic controller has been optimized and automated. Although there is no doubt that these automated techniques can produce an optimal fuzzy logic controller, the structure of such a controller is often obscure and in many cases these optimizations are simply not needed. We believe that the automatic design of a fuzzy logic controller can be simplified by using a generic rule base such as the MacVicar-Whelan rule base and using an evolutionary algorithm to optimize only the membership functions of the fuzzy sets. Furthermore, by restricting the overlapping of fuzzy sets, using triangular membership functions and singletons, and reducing the number of parameters to represent the membership functions, the design can be further simplified. This paper describes this method of simplifying the design and some experiments performed to ascertain its validity.     

多目标微分进化改进算法及应用

微分进化算法作为一种新型、简单、高效的并行随机优化算法,近年来在许多领域得到了应用,多目标微分进化便是其中的一种。针对传统多目标微分进化算法中微分进化控制参数不能自适应调整、算法容易出现早熟和退化的现象,采用惯性权重参数自适应调整的控制策略以及改进的拥挤距离算法对多目标微分进化进行改进,并将改进后的算法用于控制系统PID参数优化仿真试验。结果表明,改进后的多目标微分进化算法具有较好的收敛性和分布性以及较高的搜索效率。     

基于自适应差异进化法的电力系统无功优化

差异进化算法（DE）是一种新的进化算法,近年来的研究和应用已经展示出很大的应用潜力,但其中的某些参数需通过试验确定,影响了实用性。提出一种自适应差异进化算法（FADE）,能使算法的控制参数粮据求解问题的不同在优化过程中自适应发生改变,并应用于无功优化问题。通过IEEE-30节点算例系统的仿真结果证明,与DE和GA算法相比,模糊差异进化算法具有很强的自适应性及通用性。     

Differential evolution for optimizing the positioning of prototypes in nearest neighbor classification

Nearest neighbor classification is one of the most used and well known methods in data mining. Its simplest version has several drawbacks, such as low efficiency, high storage requirements and sensitivity to noise. Data reduction techniques have been used to alleviate these shortcomings. Among them, prototype selection and generation techniques have been shown to be very effective. Positioning adjustment of prototypes is a successful trend within the prototype generation methodology.Evolutionary algorithms are adaptive methods based on natural evolution that may be used for searching and optimization. Positioning adjustment of prototypes can be viewed as an optimization problem, thus it can be solved using evolutionary algorithms. This paper proposes a differential evolution based approach for optimizing the positioning of prototypes. Specifically, we provide a complete study of the performance of four recent advances in differential evolution. Furthermore, we show the good synergy obtained by the combination of a prototype selection stage with an optimization of the positioning of prototypes previous to nearest neighbor classification. The results are contrasted with non-parametrical statistical tests and show that our proposals outperform previously proposed methods.     

基于Tent混沌搜索的差分进化算法及其应用

针对差分进化算法求解函数优化问题存在过早收敛和不稳定等缺陷,提出一种利用Tent混沌搜索的差分进化算法(TCDE).用Tent映射初始化种群,并以种群搜索到的最优个体为基础产生Tent混沌序列,以提高种群多样性,增强算法跳出局部最优解的能力.几个典型测试函数的测试结果表明TCDE的搜索能力优于DE.将改进算法应用于近似计算导数,仿真结果表明,新算法不仅能近似求解一阶导数,还能近似计算较复杂的高阶导数.     

Differential Evolution and Levenberg Marquardt Trained Neural Network Scheme for Nonlinear System Identification

This paper proposes a new nonlinear system identification scheme using differential evolution (DE), neural network and Levenberg Marquardt algorithm (LM). Here, DE and LM in a combined framework are used to train a neural network for achieving better convergence of neural network weight optimization. A number of examples including a practical case-study have been considered for implementation of different system identification methods namely, only NN, DE+NN and DE+LM+NN. After, a series of simulation studies of these methods on the different nonlinear systems it has been confirmed that the proposed DE and LM trained NN approach to nonlinear system identification has yielded better identification results in terms of time of convergence and less identification error.     

基于差分进化算法的拥塞车流区域疏散模型

拥塞车流区域进行车辆疏散的过程中,存在较强的无序性.导致传统的车流疏散的过程中,由于车流密度突变导致的疏散准确性存在缺陷.提出差分进化算法的拥塞车流区域疏散方法.将拥塞车流区域中的车辆看作一个个独立的粒子,对粒子的初始速度和初始位置进行初始化操作,获取粒子位置和速度的变化范围.然后利用差分进化算法针对早熟的粒子进行操作,获取粒子的多样性,避免了种群过早收敛.最后利用差分进化算法对拥塞区域中车辆的连续变量函数进行优化,从而实现了拥塞车流区域的疏散.实验结果表明,利用改进算法进行拥塞车流区域疏散,能够有效提高疏散的准确率,缩短了疏散时间.     

基于混沌理论的差异演化算法研究

差异演化算法（Differential Evolution,DE）足一种基于群体个体间差异的进化计算方法,可以对高维复杂空间进行有效搜索。利用混沌（Chaos）信号的遍历性与随机性,结合DE算法,提出了一种基于混沌的DE优化算法（CDE）。与DE相比,CDE减少了控制参数。通过典型高维非线性测试函数的验证,测试结果显示该方法在优化速度、搜索效率和避免陷入局部极值点方面,大大提高DE算法的性能,在不同情兜下几乎具有最佳的函数优化性能,从而具有一定的鲁棒性。     

Differential Evolution Training Algorithm for Feed-Forward Neural Networks

An evolutionary optimization method over continuous search spaces, differential evolution, has recently been successfully applied to real world and artificial optimization problems and proposed also for neural network training. However, differential evolution has not been comprehensively studied in the context of training neural network weights, i.e., how useful is differential evolution in finding the global optimum for expense of convergence speed. In this study, differential evolution has been analyzed as a candidate global optimization method for feed-forward neural networks. In comparison to gradient based methods, differential evolution seems not to provide any distinct advantage in terms of learning rate or solution quality. Differential evolution can rather be used in validation of reached optima and in the development of regularization terms and non-conventional transfer functions that do not necessarily provide gradient information. This revised version was published online in June 2006 with corrections to the Cover Date.     

一种新的自适应非单点模糊辨识器

鉴于常规单点模糊逻辑系统在解决不确定性问题中存在的不足,该文在分析非单点模糊逻辑理论的基础之上,提出了一种新的自适应非单点模糊辨识器,并且详细论述了其相关理论、具体实现步骤和参数优化方法。针对一种糖酵解混沌振荡器模型的非线性动态系统辨识问题,采用非单点模糊逻辑系统对其进行了仿真研究,取得了较好的逼进和收敛效果,从而验证了该非单点模糊辨识器的可行性和有效性。该研究结果表明了基于非单点模糊逻辑系统构造的自适应辨识器能够在一定精度和时间区域内跟踪非线性动态系统的输出,并且非单点模糊理论将能够在控制等其它应用领域取得较好的应用效果。     

Adaptive Fuzzy Logics for Contextual Hedge Interpretation

The article presents several adaptive fuzzy hedge logics. These logics are designed to perform a specific kind of hedge detection. Given a premise set Γ that represents a series of communicated statements, the logics can check whether some predicate occurring in Γ may be interpreted as being (implicitly) hedged by technically, strictly speaking or loosely speaking, or simply non-hedged. The logics take into account both the logical constraints of the premise set as well as conceptual information concerning the meaning of potentially hedged predicates (stored in the memory of the interpreter in question). The proof theory of the logics is non-monotonic in order to enable the logics to deal with possible non-monotonic interpretation dynamics (this is illustrated by means of several concrete proofs). All the adaptive fuzzy hedge logics are also sound and strongly complete with respect to their [0,1]-semantics.     

基于模糊策略的ATM网络路由选择

文章综合考虑了用户需求和网络状态,制定出相应的模糊规则,采用模糊逻辑方法完成ATM网络的路由选择。仿真结果表明,该方法具有运算简单,实时性强,硬件实现方便的优点。     

自适应模糊控制的仿真研究

本文将一种在线变动模糊划分的自适应模糊控制应用在不同对象的控制仿真中，取得了良好的控制品质。对于不同对象，模糊控制器在线判断对象特征，预测控制过程所需能量，在线动态变化模糊集合的划分。控制器需人工设置的参数很少，易于实用到实际控制过程中，本文还给出了模糊控制系统稳定的一个充分条件。     

一种基于模糊逻辑的被动测量自适应抽样算法

结合被动抽样测量系统的特殊性,分析了模糊逻牟译控制理论应用于被动测量系统统抽样算法上的可行性,仿真结果表明,基于模糊逻辑控制理论的自适应抽样算法能够动态地调整被动测量系统地抽样间隔,使网络测量准确度和计算机资源费用达到优化。