新型并行遗传算法及其在参数估计中的应用

基于极大似然法的参数估计实质上是一个复杂的非线性优化问题,传统的优化方法计算效率较低且容易陷入局部极值。该文将单纯形法与并行遗传算法相结合,提出了一种新的并行遗传算法,可以有效地防止搜索过程中的早熟现象。应用于系统初始状态未知时的参数估计问题,获得了满意的结果。     

基于局部进化的Hopfield神经网络的优化计算方法

提出一种基于局部进化的Hopfield神经网络优化计算方法，该方法将遗传算法和Hopfield神经网络结合在一起，克服了Hopfield神经网络易收敛到局部最优值的缺点，以及遗传算法收敛速度慢的缺点。该方法首先由Hopfield神经网络进行状态方程的迭代计算降低网络能量，收敛后的Hopfield神经网络在局部范围内进行遗传算法寻优，以跳出可能的局部最优值陷阱，再由Hopfield神经网络进一步迭代优化。这种局部进化的Hopfield神经网络优化计算方法尤其适合于大规模的优化问题，对图像分割问题和规模较大的200城市旅行商问题的优化计算结果表明，其全局收敛率和收敛速度明显提高。     

自适应域多群体遗传算法求解发酵动力学模型参数

发酵动力学模型参数估计是基于最小二乘的参数估计问题,是根据满足最小二乘的标准来解决模型的最佳参数匹配,求解该问题可采用遗传算法,但简单遗传算法容易陷入局部最优。本文提出一种自适应域多群体遗传算法,它通过自调整参数域,避免陷入局部最优,同时还提高搜索到的解是全局最优解的可靠性,适用于很多领域的应用优化问题。     

一种结合Tabu搜索的自适应遗传算法研究

针对标准遗传算法（SGA）在全局优化问题中容易出现早熟和收敛速度慢,提出了一种TS-AGA算法。新算法通过将禁忌搜索（TS）和自适应遗传算法（AGA）相结合。以自适应遗传算法（AGA）为基础,用遗传算法进行全局搜索,用禁忌搜索法（TS）作局部搜索,可以加快收敛速度,同时可以抑制早熟现象,避免过早收敛到局部最优。测试函数仿真结果表明,新算法能很好的抑制早熟收敛,同时在计算速度和计算结果方面都有改进,是一种快速有效的优化算法。     

基于遗传算法的网络处理器任务分配问题

流水线模式是网络处理器常用的一种编程模式,将任务映射到处理器处理引擎上去是NP-完全问题。针对以往基于遗传算法的解决方案过早收敛的局限性,提出m Ga Pipe算法。该算法采用优化交叉算子IMX和混合变异算子Hybrid M,避免遗传算法出现过早收敛,从而显著提高遗传算法解决此类问题的准确度。仿真结果显示m Ga Pipe算法在同等条件下将收敛到最优解的比率从传统遗传算法的解决方案的9.25%提升到52.25%。     

基于模糊遗传算法的极大似然参数估计

提出用模糊遗传算法和极大似然估计法结合的方法,通过模糊推理调节遗传算法的交叉和变异概率,使参数估计不受变量初值影响,提高求解精度和收敛速度,并以三参数威布尔分布为例进行参数估计.结果表明,改进的遗传算法在求解效率和收敛性能上达到了较好的平衡,能更好地将优化方法和极大似然估计法相结合,优于一般遗传算法,从而使模糊推理方法更好地应用于数理统计中.     

基于自适应遗传算法的改进及实现

遗传算法是一种应用于优化问题的启发式算法,对求解简单问题的全局最优解具有很好的收敛性,但求解复杂优化问题则容易出现过早收敛、稳定性差等现象。为解决上述问题,论文提出了一种自适应遗传算法的改进方法,分别优化了交叉概率和变异概率的计算方式,并运用经典测试函数对该算法进行了验证,分析了此改进的优缺点。实验结果表明,改进后的自适应遗传算法比标准遗传算法可以更好地避免进化初期的停滞、过早收敛现象,具有更高的稳定性。     

基于改进型遗传算法的数字电路优化

遗传算法（ Genetic Algorithm,GA）是一种模拟生物界自然选择的智能优化算法,已经被广泛应用到各个领域。文中主要针对传统遗传算法在应用于数字电路优化设计中时所出现的未成熟收敛和收敛速度慢的问题,提出一种新的个体选择方法。该方法将保留最优个体选择方式和改进轮盘赌选择方式相结合,能够在保持种群的多样性的同时有效地提高数字电路优化的精确度。将该算法应用到最小分类网络的设计中,实验结果验证了改进算法的合理性和有效性。     

一种改进的遗传算法在无功优化中的应用

针对电力系统无功优化问题,采用遗传算法（GA）是一种有效的全局优化概率搜索算法。为了降低系统有功损耗,保证无功电力在规定范围之内,将混沌搜索引入到标准遗传算法,提出了一种结合混沌搜索的改进遗传算法。通过混沌序列搜索产生初始种群,同时对交叉、变异、选择算子进行了改进,进一步改善了遗传算法的全局寻优能力,并有效防止了局部收敛,提高了算法的收敛速度和计算精度。对系统进行了无功优化,并进行仿真。仿真结果表明,改进的遗传算法能更精确地寻找到全局最优解,并明显加快了收敛速度,性能优于标准遗传算法。     

基于改进遗传算法的电气设备仓库货位优化

货位分配问题是自动化立体仓库优化的关键。针对传统遗传算法难以收敛至全局最优解的问题,提出了一种改进遗传算法的电气设备仓库货位优化方法。该方法根据优化目标构建了数学模型,使用拉丁超立方抽样法对算法初始化环节进行优化;为了克服遗传算法的局部搜索能力差和收敛速度慢问题,使用改进自适应交叉变异及逆转操作和模拟退火操作构成改进模拟退火遗传算法。实验结果表明,相比于传统遗传算法的求解结果,改进算法显著提高了对目标函数的优化,并且其收敛性和稳定性更佳,该算法在实际工程应用中提出了有效的解决方案。     

Parameter optimization of moving horizon estimation based on hybrid intelligent algorithm

In the application of moving horizon estimation (MHE) algorithm, the window length will affect the estimation accuracy and the computing efficiency. For this kind of problem, a method of parameter optimization is proposed to obtain suitable window length. Firstly, in order to facilitate online solution, the optimization problem involved in the algorithm is transformed into a quadratic programming (QP) problem in matrix form. Secondly, for the time index and the estimated residual index that measure different properties, the normalization idea is adopted to incorporate them into the same dimension to design the fitness function, and a genetic optimization algorithm based on simulated annealing mechanism is given to search for the optimal window length. Finally, the proposed parameter optimization method is verified by two cases. The results show that the parameter optimization method has the advantages of excellent local search ability and sufficient convergence, and the window length obtained by this method can better take into account the two performance indexes of the MHE algorithm and improve the estimation performance.     

A hybrid approach using genetic and fruit fly optimization algorithms for QoS-aware cloud service composition

This paper addresses the QoS-aware cloud service composition problem, which is known as a NP-hard problem, and proposes a hybrid genetic algorithm (HGA) to solve it. The proposed algorithm combines two phases to perform the evolutionary process search, including genetic algorithm phase and fruit fly optimization phase. In genetic algorithm phase, a novel roulette wheel selection operator is proposed to enhance the efficiency and the exploration search. To reduce the computation time and to maintain a balance between the exploration and exploitation abilities of the proposed HGA, the fruit fly optimization phase is incorporated as a local search strategy. In order to speed-up the convergence of the proposed algorithm, the initial population of HGA is created on the basis of a heuristic local selection method, and the elitism strategy is applied in each generation to prevent the loss of the best solutions during the evolutionary process. The parameter settings of our HGA were tuned and calibrated using the taguchi method of design of experiment, and we suggested the optimal values of these parameters. The experimental results show that the proposed algorithm outperforms the simple genetic algorithm, simple fruit fly optimization algorithm, and another recently proposed algorithm (DGABC) in terms of optimality, computation time, convergence speed and feasibility rate.     

Multi-objective parameter estimation of induction motor using particle swarm optimization

In order to simplify the offline parameter estimation of induction motor, a method based on optimization using a particle swarm optimization (PSO) technique is presented. Three different induction motor models such as approximate, exact and deep bar circuit models are considered. The parameter estimation methodology describes a method for estimating the steady-state equivalent circuit parameters from the motor performance characteristics, which is normally available from the manufacturer data or from tests. The optimization problem is formulated as multi-objective function to minimize the error between the estimated and the manufacturer data. The sensitivity analysis is also performed to identify parameters, which have the most impact on motor performance. The feasibility of the proposed method is demonstrated for two different motors and it is compared with the genetic algorithm and the classical parameter estimation method. Simulation results show that the proposed PSO method was indeed capable of estimating the parameters over a wide operating range of the motor.     

Back analysis for rock model surrounding underground roadways in coal mine based on black hole algorithm

The huge plastic deformation is the characteristic of the underground roadways in coal mine. Therefore, to compute the stability of underground roadways, a elastic–plastic constitutive model of surrounding rock must be obtained. Many elastic–plastic constitutive models for rock mass have been proposed. In this study, a generalized constitutive law for an elastic–plastic constitutive model is applied. Using this generalized constitutive law, the problem of model identification is transformed to a problem of parameter back analysis, which is a typical and complicated optimization. To improve the efficiency of the traditional optimization method, a black hole algorithm is applied in this study. Combining the generalized constitutive law for an elastic–plastic constitutive model and black hole algorithm, a new back analysis method for model identification of rocks surrounding underground roadways in coal mine is proposed. Using this new method, the elastic–plastic constitutive models for two underground roadways in Huainan coal mine has been back-calculated. The results are compared with those of traditional genetic algorithm, fast genetic algorithm and immune continuous ant colony algorithm, that proposed in previous studies. The results show that the new model back analysis algorithm can significantly improve the computation efficiency and the computation effect, and is a very good method for back analysis the rock model surrounding underground roadways in coal mine.     

基于粒子群优化的低阶时滞系统辨识

为了解决低阶时滞系统阶跃响应辨识问题,提出基于粒子群优化的参数估计方法.方法主要包括参数初值计算和参数估计两部分.首先,采用积分方程方法估计时滞系统参数初值,通过设置参数初值估计误差,得到系统参数取值范围.然后,为了减小由观测噪声引起的参数估计误差,采用粒子群优化算法优化模型参数.最后,通过仿真实验分别验证文中方法在不同噪声条件下辨识低阶时滞系统的性能.实验表明,文中方法具有良好的参数估计精度和较强的抗噪能力,可有效解决噪声条件下低阶时滞系统的阶跃响应辨识问题.     

基于方差缩减技术的一种自适应粒子滤波器设计

退化现象是粒子滤波(PF)在非线性状态估计应用中存在的主要问题, 重采样过程一定程度上解决了粒子退化现象, 但同时带来了退化现象所导致的样本贫化问题. 本文将方差缩减技术用于PF之中, 通过给所有粒子权重赋予一个指数衰减因子来解决粒子退化现象, 该衰减因子可以根据有效粒子数进行自适应、迭代的选取, 随后通过一个定理来证明了该方法的有效性, 并基于此提出了一种自适应粒子滤波(APF)算法, 给出了算法的具体步骤, 同时对参数选取的原则和算法的局限性进行了详细的讨论. 最后, 通过一个数值例子说明了本文所提出的APF算法在计算负荷不大的条件下较采样-重要性-重采样粒子滤波(PF-SIR)、遗传粒子滤波(GPF)、粒子群优化粒子滤波(PSOPF)具有更高的估计精度.     

Parameter estimation of chaotic systems by a nonlinear time-varying evolution PSO method

An important issue in nonlinear science is parameter estimation for Lorenz chaotic systems. There has been increasing interest in this issue in various research fields, and it could essentially be formulated as a multidimensional optimization problem. A novel evolutionary computation algorithm, nonlinear time-varying evolution particle swarm optimization (NTVEPSO), is employed to estimate these parameters. In the NTVEPSO method, the nonlinear time-varying evolution functions are determined by using matrix experiments with an orthogonal array, in which a minimal number of experiments would have an effect that approximates tothe full factorial experiments. The NTVEPSO method and other PSO methods are then applied to identify the Lorenz chaotic system. Simulation results demonstrate the feasibility and superiority of the proposed NTVEPSO method.     

Robust state estimator design for uncertain linear systems using optimization techniques

The estimation of state variables of dynamic systems in noisy environments has been an active research field in recent decades. In this way, Kalman filtering approach may not be robust in the presence of modeling uncertainties. So, several methods have been proposed to design robust estimators for the systems with uncertain parameters. In this paper, an optimized filter is proposed for this problem considering an uncertain discrete-time linear system. After converting the subject to an optimization problem, three algorithms are used for optimizing the state estimator parameters: particle swarm optimization (PSO) algorithm, modified genetic algorithm (MGA) and learning automata (LA). Experimental results show that, in comparison with the standard Kalman filter and some related researches, using the proposed optimization methods results in robust performance in the presence of uncertainties. However, MGA-based estimation method shows better performance in the range of uncertain parameter than other optimization methods.     

基于遗传算法的分段Chen系统的参数估计

对比研究了单种群遗传算法和多种群遗传算法在分段Chen系统参数估计中的应用,通过构造一个合适的适应度函数,将Chen系统的多参数估计问题转化成一个多参数的寻优问题,利用遗传算法全局寻优性对其进行计算。仿真结果表明,相对于采用单种群遗传算法估计分段Chen系统参数,多种群遗传算法在准确性、鲁棒性方面具有明显的优势。