一类特殊整数规划问题的DNA计算

基于生化反应原理的DNA计算由于在解决一类困难问题,特别是完全问题上具有硅计算机无法比拟的优势,因此对DNA计算的研究具有重要意义．提出了约束方程组的“秩”以及约束方程的3种“约束补链”概念,并基于这些概念,利用在基于表面的DNA计算中采用荧光标记的策略,给出了一类特殊整数规划问题最优解的一种基于DNA计算的求解算法．新算法利用荧光猝灭技术来排除非解,从而得到满足约束条件的所有可行解,最后再通过比较所有可行解的目标函数值来求得问题的所有最优解．算法分析表明,新算法具有解读、编码简单和错误率低的特点。     

基于蚁群算法求路径规划问题的新方法及仿真

该文提出了一种基于蚁群算法求解路径规划问题的新方法及其仿真,蚁群算法就是对自然界中蚂蚁的寻食过程进行模拟而得出的一种模拟进化算法。与传统的算法相比,该算法的主要特点是正反馈和并行性,正反馈使得该算法能很快发现较好解,并行性使得该算法易于实现并行计算。虽然蚁群算法在时间复杂度上可能不如传统的算法,但是理论研究表明该方法是一种基于种群的鲁棒性较强的模拟进化算法。最后,利用Java语言对蚁群算法和改进的Dijkstra算法进行了仿真,并进行了比较。     

基于极值动力学的自组织优化算法求解TSP问题

旅行商问题(traveling salesman problem, TSP)具有很强的理论研究和工程应用价值. 在定义离散状态变量和局部适应度的基础上, 分析了TSP优化解的微观特征; 将自组织临界(self-organized criticality, SOC)的概念引入到组合优化领域, 提出了一种基于极值动力学的自组织优化算法. 该算法利用快速下降和间断涨落的动态搜索过程, 高效地遍历解空间中的局部最优解. 针对TSPLIB中典型实例, 计算结果表明其求解效率和优化性能均优于模拟退火和遗传算法等优化方法. 文中算法提供了一种全新的思路, 有助于从系统角度理解组合优化问题的复杂性, 并分析合理的优化动力学过程.     

A branch and price approach for deployment of multi-tier software services in clouds

This paper considers a service deployment problem that combines service placement and replication level decisions in a cloud computing context. The services are composed of multiple components that are to be placed on nodes in the private cloud of the service provider or, if the private cloud has limited capacity, partly in a public cloud. In the service delivery, the provider has to take into account the quality of service guarantees offered to his end-users. To solve the problem, we develop a branch and price algorithm, where the subproblems both are formulated as a linear mixed integer program and a shortest path problem with resource constraints (SPPRC) on a network with a special structure. The SPPRC can be solved by an exact label-setting algorithm, but to speed up the solution process, we develop a heuristic label-setting algorithm based on a reduced network and simplified dominance rule. Our results show that using the heuristic subproblem solver is efficient. Furthermore, the branch and price algorithm performs better than a previously developed pre-generation algorithm for the same problem. In addition, we analyze and discuss the differences in solutions that utilize resources in a public cloud to different degrees. By conducting this analysis we are able to identify some essential characteristics of good solutions.     

多目标卫星数传调度蚁群优化算法

卫星数传调度问题具有任务多、资源少、调度约束复杂等特点,为满足多目标优化调度的理论和现实需要,提出了多目标卫星数传调度蚁群优化算法。算法建立了基于任务调度关系的解构造图,提出了用于可行解构造的自适应伪随机概率决策模型,以及基于Pareto解偏离度的全局信息素更新策略。仿真结果表明,算法具有较好的Pareto前沿收敛性,各优化目标都能得到较好的指标评价值,所获得的Pareto解集规模适度,Pareto解的多样性、分布均匀性和散布范围都较好。     

Two-machine flow shop scheduling problem with blocking,multi-task flexibility of the first machine,and preemption

Blocking flow shop scheduling problem has been extensively studied in recent years; however, some applications mentioned for this problem have some additional characteristics that have not been well considered. Multi-task flexibility of machines and preemption are two of such characteristics. Multi-task flexible machines are capable of processing the operations of at least one other machine in the system. In addition, if preemption is allowed, the solution space grows, and solutions that are more efficient may be obtained. In this study, the two-machine flow shop scheduling problem with blocking, multi-task flexibility of the first machine, and preemption is investigated by considering the minimization of makespan as criterion. It is proved that the complexity of the problem is strongly NP-hard. Because of preemption and multi-task flexibility, there are infinite schedules for each sequence; however, it is shown that a dominant schedule can be defined for each sequence. Two mathematical models are proposed for optimally solving the small-sized instances. Furthermore, a variable neighborhood search algorithm (VNS) and a new variant of it, namely, dynamic VNS (DVNS), are presented to find high quality solutions for large-sized instances. Unlike the VNS algorithm, the DVNS algorithm does not need tuning for the shaking phase. Nevertheless, computational results show that DVNS has even a slightly better performance. The VNS and DVNS algorithms are also compared with some of the best-performing metaheuristics already developed for the flow shop scheduling problem with blocking and minimization of makespan as criterion. Computational results reveal that both algorithms are superior to the others for large-sized instances.     

Coupling of logistic regression analysis and local search methods for characterization of water distribution system contaminant source

Accidental or intentional drinking water contamination has long been and remains a major threat to water security throughout the world. An inverse problem can be constructed, given sensor measurements in a water distribution system (WDS), to identify the contaminant source characteristics by integrating a WDS simulation model with an optimization method. However, this approach requires numerous compute-intensive simulation runs to evaluate potential solutions; thus, determining the best source characteristic within a reasonable computational time is challenging. In this paper, we describe the development of a WDS contamination characterization algorithm by coupling a statistical model with a heuristic search method. The statistical model is used to identify potential source locations of contamination and a local search aims at further refining contaminant source characteristics. Application of the proposed approach to two illustrative example water distribution networks demonstrates its capability of adaptively discovering contaminant source characteristics as well as evaluating the degree of non-uniqueness of solutions. The results also showed that the local search as an optimizer has better performance than a standard evolutionary algorithm (EA).     

A dandelion-encoded evolutionary algorithm for the delay-constrained capacitated minimum spanning tree problem

This paper proposes an evolutionary algorithm with Dandelion-encoding to tackle the Delay-Constrained Capacitated Minimum Spanning Tree (DC-CMST) problem. This problem has been recently proposed, and consists of finding several broadcast trees from a source node, jointly considering traffic and delay constraints in trees. A version of the problem in which the source node is also included in the optimization process is considered as well in the paper. The Dandelion code used in the proposed evolutionary algorithm has been recently proposed as an effective way of encoding trees in evolutionary algorithms. Good properties of locality has been reported on this encoding, which makes it very effective to solve problems in which the solutions can be expressed in form of trees. In the paper we describe the main characteristics of the algorithm, the implementation of the Dandelion-encoding to tackled the DC-CMST problem and a modification needed to include the source node in the optimization. In the experimental section of this article we compare the results obtained by our evolutionary with that of a recently proposed heuristic for the DC-CMST, the Least Cost (LC) algorithm. We show that our Dandelion-encoded evolutionary algorithm is able to obtain better results that the LC in all the instances tackled.     

一种基于蚁群系统的组播路由算法

提出一种基于蚁群系统的求解QoS(quality of service)组播路由问题的新算法.算法中控制参数及路由选择策略根据迭代过程所处的不同阶段自适应调整.综合考虑QoS路由中所有约束条件的同时，也充分考虑各个约束自身的独立特性.实验证明算法所得的解不但较高程度地满足各个约束条件,而且多样性好、收敛速度快,能满足实际网络服务质量要求.     

考虑交通时变特性的城乡快递无人机配送优化研究

针对农村快递网点运营成本高、网点建设滞后导致的电商物流配送成本高问题,提出了城乡客运班车+无人机的快递配送模式。在考虑了配送过程中路网交通的时变特性的情况下,以无人机—车辆配送系统总成本最小为优化目标,建立了时变网络下带时间窗的无人机—车辆路径问题（TDVRPDTW）模型,并提出一个由基于最近邻思想的改进CW算法和动态规划启发式算法构成的两阶段启发式算法来求解TDVRPDTW。最后,通过算例求解验证构建模型的合理性和求解算法的有效性,为制定农村物流配送的城乡客运班车+无人机快递配送方案提供决策支持。     

Fuzzy hybrid simulated annealing algorithms for topology design of switched local area networks

Topology design of switched local area networks (SLAN) is classified as an NP-hard problem since a number of objectives, such as monetary cost, network delay, hop count between communicating pairs, and reliability need to be simultaneously optimized under a set of constraints. This paper presents a multiobjective heuristic based on a simulated annealing (SA) algorithm for topology design of SLAN. Fuzzy logic has been incorporated in the SA algorithm to handle the imprecise multiobjective nature of the SLAN topology design problem, since the logic provides a suitable mathematical framework to address the multiobjective aspects of the problem. To enhance the performance of the proposed fuzzy simulated annealing (FSA) algorithm, two variants of FSA are also proposed. These variants incorporate characteristics of tabu search (TS) and simulated evolution (SimE) algorithms. The three proposed fuzzy heuristics are mutually compared with each other. Furthermore, two fuzzy operators, namely, ordered weighted average (OWA) and unified AND–OR (UAO) are also applied in certain steps of these algorithms. Results show that in general, the variant which embeds characteristics of SimE and TS into the fuzzy SA algorithm exhibits more intelligent search of the solution subspace and was able to find better solutions than the other two variants of the fuzzy SA. Also, the OWA and UAO operators exhibited relatively similar performance.     

求解多目标最小生成树问题的改进算法

多目标最小生成树问题是典型的NP问题,Zhou和Gen提出了一种用于计数多目标最小生成树问题的所有非劣最优最小生成树的算法,但该算法无法保证能够找到所有非劣最优最小生成树.针对此问题,提出一种改进的计数算法,并定性说明改进算法能够找到问题的所有非劣最优最小生成树.改进算法在进行子树剔除时增加了一些条件.模拟实验结果表明,改进后的计数算法能够找到所有的非劣最优解.这也说明该算法具有应用的潜力.     

Elucidating multiprocessors flow shop scheduling with dependent setup times using a twin particle swarm optimization

Particle swarm optimization (PSO) is a novel metaheuristic, which has been applied in a wide variety of production scheduling problems. Two basic characteristics of this algorithm are its efficiency and effectiveness in providing high-quality solutions. In order to improve the traditional PSO, this study proposes the incorporation of a local search heuristic into the basic PSO algorithm. The new, hybrid, metaheuristic is called “twin particle swarm optimization (TPSO)”. The proposed metaheuristic scheme is applied to a flow shop with multiprocessors scheduling problem, which can be considered a real world case regarding the production line. This study, as far as the multiprocessors flow shop production system is concerned, utilizes sequence dependent setup times as constraints. Finally, simulated data confirm the effectiveness and robustness of the proposed algorithm. The data test results indicate that TPSO has potential to replace PSO and become a significant heuristic algorithm for similar problems.     

A heuristic for the periodic rural postman problem

The periodic rural postman problem (PRPP) is variant of the classical rural postman problem whose applications arise in garbage collection and street sweeping. In the PRPP each required arc/edge of a graph must be visited a given number of times over an m-day planning period in such a way that service days are equally spaced. The PRPP amounts to select a service day combination for each required arc/edge and to determine a postman tour for each day of the planning period. The objective is to minimize the total distance travelled. In this paper a simple but effective heuristic for the undirected PRPP is presented. Extensive computational results indicate that the algorithm is capable of providing high quality solutions. To our knowledge this is the first methodological paper devoted to a periodic arc routing problem.     

一种带有摄动的导向性蚁群算法

针对加入导向性局部搜索(Guided Local Search,GLS)的蚁群算法(Ant Colony Optimization,ACO)容易过早收敛的问题,提出一种带有摄动的导向性蚁群算法(Perturbation Guided Ant Colony Optimization,PGACO),该算法在当前解表现出过早收敛的趋势时,采用摄动(Perturbation)方式干扰解构建过程,使当前解移动到其邻域空间,从而产生一个新的可行解来避免算法过早收敛,提高算法求解的精度。实验结果表明,PGACO能有效地改善过早收敛问题,获得更优的可行解和执行速度,同时具有更强的全局搜索能力,能进一步提高算法的性能。     

A geometric solution to the simultaneous bounded domain stabilization problem

This paper presents an algorithmic method for solving the two-plant simultaneous bounded domain stabilization problem for SISO LTI systems. This problem has no closed form solution. The solution provides robust performance in the presence of sensor or actuator failure, or other major parameter changes. Vidyasagar (1987) studied a similar problem involving partially bounded stability domains. However, stability with respect to partially bounded domains only partially bound performance characteristics, such as control energy and transient response. The current investigation gives necessary conditions for simultaneous bounded domain stability and demonstrates a geometry-based solution algorithm which can be automated. The possible solutions to the problem and the admissible solutions are represented as sets of points in Euclidean space. The solution to the problem is found by using computational geometric techniques to detect points in the intersection of these two sets, if there is one, and deducing the simultaneous stabilizing compensator design from the points found in the intersection.     

带固定半径近邻搜索3-opt的离散烟花算法求解旅行商问题

传统烟花算法求解大规模离散问题存在收敛速度慢、求解精度不高等问题.针对旅行商问题的特点,提出一种带固定半径近邻搜索3-opt的离散烟花算法.该算法基于基本烟花算法进行离散化改进,采用整数编码的路径表示方法来表示旅行商问题的解,对爆炸算子、高斯变异算子进行离散化操作策略设计.为了使算法具有较好的局部搜索能力,提出固定半径近邻搜索3-opt策略来提高算法精度和收敛速度,同时采用不检测标志策略提高算法效率.实验结果表明:该算法能有效地求解旅行商问题,其离散烟花算子在全局收敛能力、收敛精度、求解时间和稳定性等方面均优于传统烟花算子;基准测试算例的最优解平均误差率仅为0.002％,优于对比算法.     

A parallel hybrid greedy branch and bound scheme for the maximum distance-2 matching problem

We present a new highly parallel algorithm for fast determination of near-optimal solutions to the NP-hard problem of identifying a maximum distance-2 matching in arbitrary graphs. This problem, known as D2EMIS, has important applications such as determining the maximum capacity of the media access (MAC) layer in wireless ad-hoc networks [1]. It can also be seen as a maximum 2-packing problem [2] on the edge-to-vertex dual graph of the original graph. Our algorithm extends the GRASP [3] philosophy in that partial solutions are constructed by adding in a greedy adaptive manner the “best” nodes that can be found; however, when there are multiple alternatives that can be selected in an iteration, the algorithm branches into as many paths as there are (greedy) alternatives. The algorithm, using appropriate bounds to prune partial solutions that cannot be optimal, produces very fast near-optimal solutions that compare very well against other distributed algorithms and random greedy heuristics proposed before or variants thereof, or exact methods (Integer Programming or Maximum Satisfiability state-of-the-art solvers).     

融入概率学习的混合差分进化算法求解绿色分布式可重入作业车间调度

本文针对绿色分布式可重入作业车间调度问题(GDRJSSP), 提出一种融入概率学习的混合差分进化算法 (HDE PL), 以实现最大完工时间和总能耗最小. 根据GDRJSSP的问题特点, 设计编码和解码规则, 并采用差分进化 算法执行全局搜索来发现优质解区域. 为能更明确地引导全局搜索方向, 设计基于贝叶斯网络结构的多维概率模型 合理学习和积累优质解(即当前种群中的较优解)的模式信息. 结合问题解的结构特征, 提出基于关键路径的4种邻 域结构来构造局部搜索, 并设计基于非关键路径的节能策略来提升算法获取低能耗非劣解的能力. 仿真实验和算 法对比验证了HDE PL可有效求解GDRJSSP.     

Robust optimization using multi-objective particle swarm optimization

This article proposes an algorithm to search for solutions which are robust against small perturbations in design variables. The proposed algorithm formulates robust optimization as a bi-objective optimization problem, and fi nds solutions by multi-objective particle swarm optimization (MOPSO). Experimental results have shown that MOPSO has a better performance at fi nding multiple robust solutions than a previous method using a multi-objective genetic algorithm.