分散搜索算法求解多目标优化问题

最近涌现了各种进化方法来解决多目标优化问题,分散搜索也是一种可以解决多目标问题的算法。该算法的结构引用进化算法的杂交和变异算子来增强它的性能,但该算法与其他进化算法的不同在于一系列操作策略不再基于随机性原理,而是运用“分散-收敛集聚”的迭代机制。论文在多目标优化问题区域讨论分散搜索算法,寻找多目标的非支配集或Pareto最优解。实验表明,分散搜索算法具有很好的收敛性和分布性。     

单线图动态规划最优布局成图技术

提出了一种基于动态规划算法得到布局最优解实现区域电网单线图生成的方法.根据电网空间数据构建拓扑模型,执行广度优先算法得到多个能构成连通图的邻接矩阵以及矩阵遍历序列,根据邻接矩阵宽度计算出能容纳全部设备的正方形范围,并建立了设备最小间距为优化目标的数学模型.提出了动态规划最优布局求解的算法,应用该算法求解布局最优解数组,最后按照最少交叉原则进行正交化处理.应用实例表明通过最优解布局的成图美观且高效.     

混合蚁群算法求解分布式系统任务分配问题

任务分配问题是被公认的NP-hard问题,应用广泛。在对分布式系统任务分配问题进行分析的基础上,将蚂蚁寻求任务分配方案的过程用一种新的图形表示方式来实现。针对蚁群优化算法易陷入局部最优的固有缺陷,提出了一种新的混合算法,该算法将蚁群优化算法与简单禁忌搜索算法相结合,增强了算法的局部搜索能力,提高了任务分配问题解的质量。实验结果表明混合算法的求解性能较优。     

基于中心解的改进人工蜂群算法

为了解决人工蜂群(ABC)算法在用于函数优化时所具有的局部探索能力不强、收敛精度不高的问题,提出一种基于中心解的人工蜂群算法。该算法结合中心解和当前最优候选解的优点,并将中心解引入到跟随蜂的局部变异策略中。跟随蜂采用轮盘赌的形式,选择某些适应度值较好的蜜源,在雇佣蜂中心解的基础上深度局部寻优,并在每次迭代中逐维更新蜜源每一维度的值。为了验证该算法的有效性,选择六个基准测试函数对三种算法进行仿真对比实验。与标准ABC算法和Best-so-far ABC算法相比,改进的ABC算法的求解精度有较大幅度提高,特别是对于Rastrigin函数,两种不同维数下均达到了理论最优值。实验结果表明:所提算法在收敛速度和寻优精度上都有明显改善。     

文化基因算法在第四方物流路径规划中的应用

第四方物流路径问题是复杂的组合优化问题。基本遗传算法在第四方物流路径问题上存在随着问题规模扩大,算法的成功率和准确率不断下降等缺点。针对基本的遗传算法已经不能满足规模较大的第四方物流问题等缺点,结合实验分析,提出了一种以遗传算法为全局搜索策略的文化基因算法,并针对第四方物流的问题特点设计了相应的局部搜索策略。实验结果表明,与基本遗传算法相比,该混合算法不仅在求解质量上有了较大的改进,并且在大规模第四方物流问题上也能获得质量较好的解,算法的成功率和准确率明显高于基本的遗传算法。因此,基于遗传算法的文化基因算法是解决大规模第四方物流路径问题的一种有效方法。     

Local Search Algorithms for the Maximal Planar Layout Problem

The problem of laying out facilities is practically important in a modern manufacturing environment. This problem can be formulated as a weighted maximal planar graph in which vertices represent facilities and edge weights represent desirability measures between facilities. The objective is to find a planar graph that can be drawn on a plane without any edges intersecting with the highest sum of edge weights. Exact solution method can only solve small sized problems. In this paper, local search algorithms based on steepest ascent, hybrid simulated annealing and tabu search with a non-monotonic cooling schedule, and tabu search with a hashing function are developed to obtain near-optimal solutions. Different search strategies are investigated. All the developed algorithms are compared with existing construction methods and a branch and bound exact algorithm on a set of practical size problems. The proposed algorithms performed very well in terms of solution quality and computation time.     

构造最小生成树的量子算法

图的最小生成树问题是网络优化中的一类基本问题。目前构造最小生成树的算法都是基于传统计算机的算法如Prim算法和Kruskal算法。该文提出了一个用于构造图的最小生成树的量子算法,它结合量子搜索的方法和经典Kruskal算法的思想,对于n个节点m条边的图,依次搜索出n-1条边使它们构成一棵最小生成树。这一算法的时间复杂性为O(nm√)。与经典Kruskal算法相比,在同等条件下,该文的算法有较快的加速。     

Finding of optimal binary morphological erosion filter via greedy and branch & bound searching

In this paper, an effective and efficient algorithm for finding the optimal morphological erosion filter on binary images is proposed. The design of morphological erosion filter is based on statistical method by minimizing mean square error. Traditionally, finding optimal morphological erosion filters requires searching through a large number of structuring-element combinations which is a long search and time consuming procedure. In the proposed method, the problem of finding the optimal solution is reduced to the problem of searching a minimal path on the error code graph (ECG). Since the graph satisfies some greedy criteria, only few nodes need to be traversed and examined. Experiments are conducted to illustrate the validity of our proposed method.This work is supported by National Science Council of Taiwan under grant NSC 83-0404-E-008-022.     

面向主动配电网实时优化调度的图强化学习方法

主动配电网的新能源、储能等能源形式可以有效提高运行的灵活性和可靠性, 同时新能源和负荷也给配电网带来了双重不确定性, 致使主动配电网的实时优化调度决策维度大、建模精度差. 针对这一问题, 本文提出结合图神经网络和强化学习的图强化学习方法, 避免对复杂系统的精准建模. 首先, 将实时优化调度问题表述为马尔可夫决策过程, 并将其表述为动态序贯决策问题. 其次, 提出了基于物理连接关系的图表示方法, 用以表达状态量的隐含相关性. 随后, 提出图强化学习来学习将系统状态图映射到决策输出的最优策略. 最后, 将图强化学习推广到分布式图强化学习. 算例结果表明, 图强化学习在最优性和效率方面都取得了更好的效果.     

Hybrid heuristic search approach for deadlock-free scheduling of flexible manufacturing systems using Petri nets

Based on the Petri net models of flexible manufacturing systems (FMSs), this paper focuses on deadlock-free scheduling problem with the objective of minimizing the makespan. Two hybrid heuristic search algorithms for solving such scheduling problems of FMSs are proposed. To avoid deadlocks, the deadlock control policy is embedded into heuristic search strategies. The proposed algorithms combine the heuristic best-first strategy with the controlled backtracking strategy based on the execution of the Petri nets. The scheduling problem is transformed into a heuristic search problem in the reachability graph of the Petri net, and a schedule is a transition sequence from the initial marking to the final marking in the reachability graph. By using the one-step look-ahead method in the deadlock control policy, the safety of a state in the reachability graph is checked, and hence, deadlock is avoided. Experimental results are provided and indicate the effectiveness of the proposed hybrid heuristic search algorithms in solving deadlock-free scheduling problems of FMSs. Especially, the comparison against previous work shows that both new algorithms are promising in terms of solution quality and computing times.     

一种基于GN算法的动态图划分方法

随着图规模的急剧增长,对动态图进行实时处理的需求日益增加。大多现有的算法针对静态图划分是有效的,直接用其处理动态图会带来较大的通信开销。针对该问题,提出一种基于GN算法的动态图划分方法。首先收集一段时间内加入动态图中的顶点;然后,利用GN算法对这些新加入的顶点进行预划分,产生若干个内部联系紧密的社区;最后,将预划分产生的社区结果插入到已经划分好的当前图中。实验从交叉边数和负载均衡度两方面将该方法与传统流式划分方法进行比较,结果表明,在公开数据集上,该方法的交叉边数降低了13%,负载均衡度减少了42.3%。由此可见,该方法的划分质量明显优于传统的流式划分方法。     

Efficient multi-scale community search method based on spectral graph wavelet

Community search is an important problem in network analysis, which has attracted much attention in recent years. As a query-oriented variant of community detection problem, community search starts with some given nodes, pays more attention to local network structures, and gets personalized resultant communities quickly. The existing community search method typically returns a single target community containing query nodes by default. This is a strict requirement and does not allow much flexibility. In many real-world applications, however, query nodes are expected to be located in multiple communities with different semantics. To address this limitation of existing methods, an efficient spectral-based Multi-Scale Community Search method (MSCS) is proposed, which can simultaneously identify the multi-scale target local communities to which query node belong. In MSCS, each node is equipped with a graph Fourier multiplier operator. The access of the graph Fourier multiplier operator helps nodes to obtain feature representations at various community scales. In addition, an efficient algorithm is proposed for avoiding the large number of matrix operations due to spectral methods. Comprehensive experimental evaluations on a variety of real-world datasets demonstrate the effectiveness and efficiency of the proposed method.     

极大熵和声搜索算法求解多目标优化*

给出了求解多目标优化问题的一个新算法。首先利用极大熵函数,将多目标优化问题转换为一个单目标优化问题;然后利用和声搜索算法对其进行求解,进而得到多目标优化问题的有效解。该算法对目标函数的解析性质没有要求且容易实现,数值结果表明了该方法是有效的。     

基于禁忌搜索的启发式算法求解球体Packing问题*

为求解具有NP难度的球体Packing问题,通过将禁忌搜索方法与基于自适应步长的梯度下降法和二分法相结合,提出了一个启发式算法。对50个等球算例进行了实例测试,算法改进了其中44个算例的目前最优结果。大量的实例计算结果表明,该启发式算法是求解球体Packing问题的一个有效算法。     

A new neural network algorithm for planarization problems

To deal with the planarization problem widely used in many applications including routing very-large-scale integration （VLSI） circuits, this paper points out that only when its vertices are arranged in some specific order in a line can a planar graph be embedded on a line without any cross connections or cross edges. Energy function is proposed to meet the need of embedding a graph on a single line and route it correctly. A Hopfield network is designed according to the proposed energy function for such embedding and routing. The advantage of the proposed method is that it not only can detect if a graph is a planar one or not, but also can embed a planar graph or the maximal planar subgraph of a non-planar graph on a single line. In addition, simulated annealing is employed for helping the network to escape from local minima during the running of the Hopfield network. Experiments of the proposed method and its comparison with some existent conventional methods were performed and the results indicate that the proposed method is of great feasibility and effectiveness especially for the planarization problem of large graphs.     

混合算法的邻域结构变更研究及在排样问题上的应用

本文研究了全局搜索算法和局部搜索算法的混合机制,设计了基于邻域搜索和遗传算法的混合搜索算法。该算法结合了遗传算法的全局搜索特性和邻域局部贪婪搜索特性;在分析排样问题碰靠过程特征的基础上,构建了排样问题邻域假设,当邻域假设满足时,遗传算法+邻域搜索能很好发挥作用;当不能判断邻域结构是否满足邻域假设时,提出了建立遗传算法+匹配变邻域的搜索算法,该算法兼顾了组合优化中邻域搜索的局部搜索无效的情况,实现了匹配的变邻域混合算法在排样优化问题中的应用。实例结果标明,排样图形不一样,其求解难度不一样,该算法均搜索到了更好的排样模式,验证了算法的有效性。     

一种求解两级车辆路径问题的Memetic 算法

两级车辆路径问题是指物资必须先由中心仓库配送至中转站(第1级),再由中转站配送至客户(第2级)的一种车辆路径问题。针对该NP难问题提出一种Memetic算法通过自底向上的方式进行求解。首先利用改进的最优切割算法MDVRP-Split将客户合理分配至中转站;然后采用局部搜索解决第1级问题,交叉产生的精英个体通过局部搜索改进。标准算例的测试结果表明,所提出算法更注重求解质量与求解效率的平衡,性能优于其他现有的两种算法。     

图着色问题的启发式搜索蚂蚁算法

针对经典的图着色问题,该文在随机序列启发式搜索求解的基础上,引进蚂蚁算法优化思想,设计了一种新型算法,有效地避免了启发式搜索易陷入局部极小的缺陷。通过给地图着色和仿真实验结果表明,该方法对图着色问题的求解是可行、有效的,且具有通用性。     

A copula-based hybrid estimation of distribution algorithm for m-machine reentrant permutation flow-shop scheduling problem

Aiming at the m-machine reentrant permutation flow-shop scheduling problem (MRPFSSP), a copula-based hybrid estimation of distribution algorithm (CHEDA) is presented to minimize the makespan criterion. Firstly, we establish both the operation-based model and the graph model for MRPFSSP, and then several inherent properties about critical path and blocks are proposed and analyzed. Secondly, the copula theory is utilized to build CHEDA’s probability model (i.e., the joint distribution function, JDF) to efficiently extract the useful information from the excellent individuals. Thirdly, the global search based on the JDF model and a new population sampling method is designed to find the promising sub-regions in the total solution space. Fourthly, a problem-dependent local search based on the critical path and blocks is embedded into CHEDA to enhance the local exploitation ability. Finally, simulation experiments and comparisons demonstrate the effectiveness of the proposed CHEDA.     

病毒进化遗传算法的车辆调度优化模型

为了提高车辆调度优化效率,提出一种病毒进化遗传算法的车辆调度优化模型。建立车辆调度的数学模型,采用遗传算法对模型进行求解,并采用病毒群体感染主群体,主群体在历代个体间纵向传递信息以利于全局优化,病毒群体通过感染操作在同代个体间横向传递信息利于局部搜索,进行仿真对比实验。结果表明,病毒进化遗传算法较好地解决了标准遗传算法存在的不足,加快了车辆调度优化问题的求解效率,获得了更优的车辆调度方案,具有较高的应用价值。