Methods based on discrete optimization for finding road network rehabilitation strategies

We study a dynamic optimization problem arising in the (long-term) planning of road rehabilitation activities. In this area one seeks a pavement resurfacing plan for a road network under budget constraints. Our main approach is to model this as an integer programming problem with underlying dynamic programming structure. We investigate properties of this model and propose a solution method based on Lagrangian relaxation where one gets subproblems that are shortest path problems. Some computational experiences based on realistic data are reported.     

改进的万有引力搜索算法在函数优化中的应用

万有引力搜索算法应用于函数优化问题时易陷入局部最优解且优化精度不高。针对这些问题,提出了一种改进的万有引力搜索算法。该算法通过引入反向学习策略、精英策略和边界变异策略,显著地提高了万有引力搜索算法中粒子的探索能力与开发能力,获得了较强的全局优化能力和局部优化能力。通过对6个非线性基准函数进行仿真实验,结果表明：与基本的万有引力搜索算法、加权的万有引力搜索算法和人工蜂群算法相比,改进的万有引力搜索算法在求解复杂函数的优化问题时具有更好的优化性能。     

基于SQP局部搜索的多子群果蝇优化算法

针对基本果蝇优化算法在寻优过程中种群多样性降低导致算法易陷入早熟收敛的问题,提出了基于序列二次规划（SQP）局部搜索的多子群果蝇优化算法（MFOA-SQP）。新算法将果蝇种群均匀划分为多个子群,并引入粒子群算法中的惯性权重和学习因子,协同调节果蝇移动方向和步长;每隔一定迭代次数重新划分子群,避免种群单一化,使算法更易跳出局部最优;对子群最优个体进行SQP搜索,提高局部寻优性能。通过6个测试函数和优化广义回归神经网络对银行客户进行分类的实验结果表明,算法在寻优精度和速度方面性能优越,能够有效提高广义回归神经网络的分类准确率。     

基于PSO的预测控制及在聚丙烯中的应用

输入输出受限非线性系统的预测控制问题,可以看作是一个难以直接求解的约束非线性优化问题。针对预测控制在解决此类优化问题时,存在易收敛到局部极小或者非可行解,对初始值敏感等缺点,提出了一种基于微粒群优化方法的非线性预测控制算法。采用微粒群优化算法（PSO）作为模型预测控制的滚动优化方法,在线实时求解最优控制律。将PSO与序贯二次规划（SQP）算法进行对比仿真实验,求解两个标准函数优化问题,结果表明PSO能够快速有效地求得全局最小点,而SQP则很容易陷入局部极小点。将该算法应用于丙烯聚合反应过程的温度控制中,仿真结果显示了该方法的有效性。     

Control oriented modeling and optimization of one dimensional packed bed model of underground coal gasification

To account for nonlinear nature and huge model uncertainties of underground coal gasification (UCG) process, a robust model based control strategy is to be employed. The available models in the literature do not lend themselves to control applications easily. In this work a control oriented one dimensional (1-D) packed bed model of UCG is developed, which can be used in a closed loop configuration with a robust controller to maintain a desired heating value of the exit gas mixture by manipulating the flow rate of injected gases. The model is also capable of predicting time and space profiles of some important parameters, which include solid temperature, composition of exit gas mixture, rates of different chemical reactions and expected life of the UCG reactor in response to different operating conditions and coal properties. Most of these parameters are either impossible or very expensive to measure. There is uncertainty in some coal properties which is addressed by optimizing few input parameters using sequential quadratic programming (SQP) algorithm, a nonlinear optimization technique. The model results are compared with actual field trials which show a good agreement for the calorific value of exit gas.     

基于线性规划和遗传–粒子群算法的烧结配料多目标综合优化方法

针对钢铁企业二次配料工艺,本文采用将硫含量折算为可比成本,兼顾节能减排目标和配料成本,建立了二次配料多目标优化模型;提出了一种基于线性规划和遗传–粒子群算法（GA–PSO）的钢铁烧结配料优化方法.首先采用线性规划算法进行求解,若线性规划方法无法求得最优解,则采用GA–PSO算法进行搜索.该方法应用于某钢铁企业360m2生产线的＂配料优化与决策支持系统＂中,实际运行结果表明,该算法在保证烧结矿质量的前提下,能够有效地减少二氧化硫排放,降低配料成本.     

A modified Intelligent Water Drops algorithm and its application to optimization problems

The Intelligent Water Drop (IWD) algorithm is a recent stochastic swarm-based method that is useful for solving combinatorial and function optimization problems. In this paper, we investigate the effectiveness of the selection method in the solution construction phase of the IWD algorithm. Instead of the fitness proportionate selection method in the original IWD algorithm, two ranking-based selection methods, namely linear ranking and exponential ranking, are proposed. Both ranking-based selection methods aim to solve the identified limitations of the fitness proportionate selection method as well as to enable the IWD algorithm to escape from local optima and ensure its search diversity. To evaluate the usefulness of the proposed ranking-based selection methods, a series of experiments pertaining to three combinatorial optimization problems, i.e., rough set feature subset selection, multiple knapsack and travelling salesman problems, is conducted. The results demonstrate that the exponential ranking selection method is able to preserve the search diversity, therefore improving the performance of the IWD algorithm.     

Parameter selection of support vector regression based on hybrid optimization algorithm and its application

Choosing optimal parameters for support vector regression (SVR) is an important step in SVR design, which strongly affects the performance of SVR. In this paper, based on the analysis of influence of SVR parameters on generalization error, a new approach with two steps is proposed for selecting SVR parameters . First the kernel function and SVM parameters are optimized roughly through genetic algorithm, then the kernel parameter is finely adjusted by local linear search. This approach has been successfully applied to the prediction model of the sulfur content in hot metal. The experiment results show that the proposed approach can yield better generalization performance of SVR than other methods.     

基于DE和PSO的混合智能算法及其在模糊EOQ模型中的应用*

设计了融合差分进化和PSO算法优点的混合智能优化算法DEPSO,通过在粒子迭代过程中,随机选择一定数量的粒子进行差分进化操作,增加粒子的多样性,使陷入局部极小的粒子逃出,以保证DEPSO的全局收敛性能,并采用典型测试函数验证了DEPSO的性能。针对模糊相关机会规划EOQ模型求解难题,设计了基于模糊模拟方法和DEPSO的智能求解算法来计算模糊事件的可信性,从而得到了使库存费用不超过预算水平的可信度最大的最优订货量,算例证实了此求解算法的有效性。     

Parameter selection of support vector regression based on hybrid optimization algorithm and its application

Choosing optimal parameters for support vector regression （SVR） is an important step in SVR. design, which strongly affects the pefformance of SVR. In this paper, based on the analysis of influence of SVR parameters on generalization error, a new approach with two steps is proposed for selecting SVR parameters, First the kernel function and SVM parameters are optimized roughly through genetic algorithm, then the kernel parameter is finely adjusted by local linear search, This approach has been successfully applied to the prediction model of the sulfur content in hot metal. The experiment results show that the proposed approach can yield better generalization performance of SVR than other methods,     

A new gradient based particle swarm optimization algorithm for accurate computation of global minimum

Stochastic optimization algorithms like genetic algorithms (GAs) and particle swarm optimization (PSO) algorithms perform global optimization but waste computational effort by doing a random search. On the other hand deterministic algorithms like gradient descent converge rapidly but may get stuck in local minima of multimodal functions. Thus, an approach that combines the strengths of stochastic and deterministic optimization schemes but avoids their weaknesses is of interest. This paper presents a new hybrid optimization algorithm that combines the PSO algorithm and gradient-based local search algorithms to achieve faster convergence and better accuracy of final solution without getting trapped in local minima. In the new gradient-based PSO algorithm, referred to as the GPSO algorithm, the PSO algorithm is used for global exploration and a gradient based scheme is used for accurate local exploration. The global minimum is located by a process of finding progressively better local minima. The GPSO algorithm avoids the use of inertial weights and constriction coefficients which can cause the PSO algorithm to converge to a local minimum if improperly chosen. The De Jong test suite of benchmark optimization problems was used to test the new algorithm and facilitate comparison with the classical PSO algorithm. The GPSO algorithm is compared to four different refinements of the PSO algorithm from the literature and shown to converge faster to a significantly more accurate final solution for a variety of benchmark test functions.     

基于混沌搜索和权重学习的教与学优化算法及其应用

针对教与学优化算法容易陷入早熟收敛的问题,本研究提出了一种基于混沌搜索和权重学习的教与学优化（teaching-learning-based optimization algorithm based on chaotic search and weighted learning,TLBO-CSWL）算法。在TLBO-CSWL算法的教学阶段,不仅利用权重学习得到的个体来指引种群的进化,而且还使用正态分布随机数来替代原有的均匀随机数。另外,TLBO-CSWL还使用Logistics混沌搜索策略来提高其全局搜索能力。仿真结果表明,TLBO-CSWL的整体优化性能要好于其他所比较的算法。最后,将TLBO-CSWL用于求解非合作博弈纳什均衡问题,获得满意的结果。     

自适应布谷鸟算法及其在化工优化中的应用

动态优化问题广泛存在于化工自动控制过程中,对其求解是化工过程工业发展的一个不可忽视的环节。群智能算法求解此类优化问题时不可避免地存在后期收敛速度慢、求解精度的不高等不足,这一直是一个研究热点。针对新兴的布谷鸟算法与以上问题,提出一种变步长自适应布谷鸟搜索算法(VSACS),将基本布谷鸟搜索(CS)算法中的随机步长改进成根据迭代次数自适应调整的步长。通过15个标准测试函数的测试,结果验证了改进的算法有较快的收敛速度和较高的求解精度。最后将改进的算法用于批示反应器、管式反应器、生物反应器等3个典型的化工动态优化问题中,获得了满意的实验结果,同时也进一步表明该算法的有效性。     

一种改进细菌觅食优化算法及其在软测量建模中的应用

针对软测量建模中模型参数的优化需求,在分析细菌觅食优化算法(BFOA)和粒子群优化(PSO)算法的基础上,将二者有机结合,提出了一种新型细菌觅食粒子群混合优化算法(BSOA)。该算法将PSO粒子移动的思想引入BFOA,有效解决了BFOA趋向性操作中细菌位置更新的盲目性。将其分别用于典型函数的寻优与成品油研究法辛烷值最小二乘支持向量机(LSSVM)模型参数的优化,仿真结果表明:该方法有效增强了算法的全局寻优能力与收敛速度,并在一定程度上改善了模型的预测精度与泛化能力。     

免疫遗传算法及在新产品投入计划中的应用

提出一种新的求解复杂约束优化问题的免疫遗传算法. 算法首先产生大量抗原来训练抗体, 从而建立起一个具有自体和非自体识别能力的免疫系统. 将该免疫系统嵌入到遗传算法中, 即可在遗传过程中不经解码就能识别非法或不可行的染色体. 算法有效地改进了遗传算法求解复杂约束优化问题的性能. 算法用于求解用半无限规划模型描述的新产品投入计划问题, 获得了满意的结果.     

A human learning optimization algorithm and its application to multi-dimensional knapsack problems

Inspired by human learning mechanisms, a novel meta-heuristic algorithm named human learning optimization (HLO) is presented in this paper in which the individual learning operator, social learning operator, random exploration learning operator and re-learning operator are developed to generate new solutions and search for the optima by mimicking the human learning process. Then HLO is applied to solve the well-known 5.100 and 10.100 multi-dimensional knapsack problems from the OR-library and the performance of HLO is compared with that of other meta-heuristics collected from the recent literature. The experimental results show that the presented HLO achieves the best performance in comparison with other meta-heuristics, which demonstrates that HLO is a promising optimization tool.     

梯度微粒群优化算法及其收敛性分析

针对标准微粒群优化算法微粒运动轨迹的收敛性进行了分析.给出并证明了微粒运动轨迹收敛的充分条件.提出一种简便的等高线图判别法,该方法能够通过参数的位置判断微粒轨迹是否收敛并衡量收敛速度.为提高算法的收敛速度.构造出一种梯度微粒群优化算法,给出并证明了该方法收敛的充分条件.仿真结果表明,梯度微粒群优化算法具有优良的搜索性能.     

基于离散人工蜂群算法的云任务调度优化

针对现今云计算任务调度只考虑单目标和云计算应用对虚拟资源的服务的质量要求高等问题,综合考虑了用户最短等待时间、资源负载均衡和经济原则,提出一种离散人工蜂群(ABC)算法的云任务调度优化策略。首先,从理论上建立了云任务调度的多目标数学模型;然后,结合偏好满意度策略并引入局部搜索算子和改变侦察蜂搜索方式,提出多目标离散型人工蜂群(MDABC)算法的优化策略。通过不同的云任务调度仿真实验,显示了改进离散人工蜂群算法相对于基础离散人工蜂群算法、遗传算法以及经典贪心算法,能够得到较高的综合满意度,表明了改进离散人工蜂群算法能够更好地改善虚拟资源中云任务调度系统的性能,具有一定的普适性。