供应链中控制多级存储的射频辨识Push/Pull混合策略设计与仿真

由于射频辨识(radio frequency identification,RFID)激励的电子看板系统能够从远端看见供应链节点企业库存的状况,使得广域分布的供应链多级存储能够实现RFID激励的Pull控制.本文根据供应链分销网络多级存储的结构特点,以及系统运作期间各阶段节点企业的功能,在不同阶段采用不同的控制策略.因此,设计了多种不同的RFID激励的Push/Pull混合控制策略.为了比较和验证各混合策略对多级存储的控制性能,建立了以总库存成本、总缺货损失、总运行成本和库存周转率作为评价策略性能的指标体系.由于供应链系统的动态性与随机性,难以进行数学建模和精确求解,因此基于离散事件系统仿真原理,设计并实现了仿真模型.通过对各策略下多种结构的供应链分销网络多级存储的仿真,验证并分析了制造商阶段采用Push控制,分销商和零售商阶段采用Pull控制的策略的有效性和最优性.     

基于协同进化的约束多目标优化算法

针对约束多目标优化算法存在难以有效地兼顾收敛性和多样性的问题,提出一种基于协同进化的约束多目标优化算法.第一阶段,通过基于稳态演化的可行解搜索方式得到一个具有一定数量可行解的种群;第二阶段,将这个种群拆分为两个子种群,并通过双子种群协同进化的方式实现对收敛性和多样性的兼顾;最后采用标准约束多目标优化问题CF1～CF7、...     

物料需求计划与准时生产制的对比分析

本文对西方的物料需求计划(MRP)和日本的准时生产制(JIT)这两种生产管理控制方法的产生背景、构成要素、运行机制及性能进行了对比。综述了将二者结合起来的混合控制策略的研究情况。探讨了不同控制策略在计算机集成制造系统中与制造过程集成的可能性。并结合中国国情,分析了混合控制策略的应用前景。     

CIMS企业中应用Push/Pull生产方式的研究

文章首先对MRP＿II和JIT生产方式进行了对比,分析各自的优缺点,并针对性地提出一种适合于CIMS类企业Push／Pull生产方式.然后,作者详细研究了Push／Pull生产方式下原材料投入的Push控制方法和后续加工的Pull控制方法.最后,作者研究了Push／Pull生产方式下生产计划和调度策略的基本框架、系统的总体结构和JIT的主生产计划方法等.     

Biogeographic harmony search for emergency air transportation

Harmony search (HS) and biogeography-based optimization (BBO) are two metaheuristic optimization methods which have demonstrated effectiveness on a wide variety of optimization problems. The paper proposes a new hybrid biogeographic harmony search (BHS) method, which integrates the blended migration operator of BBO with HS to enrich harmony diversity, and thus achieves a much better balance between exploration and exploitation. We then apply the BHS method to an emergency air transportation problem, and show that the proposed method is very competitive with the state-of-the-art BBO, HS, and other comparative algorithms on a set of problem instances from real-world disaster relief operations in China.     

Web应用环境下单点登录模式的研究

随着各种网络服务的不断普及和Web服务技术的不断发展,人们对单点登录的需求随之增强,有关单点登录的技术和解决方案也在不断涌现。本文从登录认证的不同实现方式以及单点登录系统内不同服务间的相互关系出发,提出了单点登录系统两种类型的四种基本实现模式:简单Push模式、简单Pull模式、服务流Push模式和服务流Pull模式,并结合每种模式的不同特点对不同的实现模式进行了比较。     

Push/Pull技术及在Domino上的实现

Pull是传统的信息传送模式,Push则是近年来得到迅速发展的与Pull相对的一种信息传送模式。该文对两种传送模式技术作了简要论述,并介绍了一个采用Push／Pull技术的系统的设计与实现。     

A stochastic algorithm for makespan minimized multi-agent path planning in discrete space

Makespan minimized multi-agent path planning (MAPP) requires the minimization of the time taken by the slowest agents to reach its destination. The resulting minimax objective function is non-smooth and the search for an optimal solution in MAPP can be intractable. In this work, a maximum entropy function is adopted to approximate the minimax objective function. An iterative algorithm named probabilistic iterative makespan minimization (PIMM) is then proposed to approximate a makespan minimized MAPP solution by solving a sequence of computationally hard MAPP minimization problems with a linear objective function. At each iteration, a novel local search algorithm called probabilistic iterative path coordination (PIPC) is used to find a sufficiently good solution for each MAPP minimization problem. Experimental results from comparative studies with existing MAPP algorithms show that the proposed algorithm strikes a good tradeoff between the quality of the makespan minimized solution and the computational cost incurred.     

A complete multi-robot path-planning algorithm

In the domain of multi-robot path-planning problems, robots must move from their start locations to their goal locations while avoiding collisions with each other. The research problem that we addressed is to find a complete solution for the multi-robot path-planning problem. Our first contribution is to recognize the solvable instances of the problem with our solvability test; the theoretical analysis has already been provided to show the validity of this test. Our second contribution is to solve this problem completely, in polynomial time, with the Push and Spin (PASp) algorithm. Once the problem was solved, we found decisions within the complete solution that may improve the performance of the complete algorithm. Hence, our third contribution is to improve the performance by selecting the best path from the set of complete paths. We refer to the improved version of our algorithm as the improved PASp algorithm. In terms of the completeness evaluation, the mathematical proofs demonstrate that the PASp is a complete algorithm for a wider class of problem instances than the classes solved by the Push and Swap (PAS), Push and Rotate (PAR), Bibox or the tractable multi-robot path-planning (MAPP) algorithms. Moreover, PASp solves any graph recognized to be solvable without any assumptions. In addition, the theoretical proof of the PASp algorithm showed completive polynomial performance in terms of total-path-lengths and execution time. In our performance evaluation, the experimental results showed that the PASp performs competitively, in reasonable execution time, in terms of number of moves compared to the PAS, PAR, Bibox and MAPP algorithms on a set of benchmark problems from the video-game industry. In addition, the results showed the scalability and robustness of PASp in problems that can be solved only by PASp. Such problems require high levels of coordination with an efficient number of moves and short execution time. In grid and bi-connected graphs with too many cycles, PASp required more moves and more time than the PAS, PAR and Bibox algorithms. However, PASp is the only algorithm capable of solving such instances with only one unoccupied vertex. Furthermore, adding heuristic search and smooth operation to the improved PASp showed significant further improvement by reducing the number of moves for all problem instances. PASp produced the best plans in a bit higher time. Finally, the PASp algorithm solves a wider class of problems and performs more completely in very complex/crowded environments than other state-of-art algorithms. Additionally, the Spin operation introduces a novel swapping technique to exchange two items and restore others in a graph for industrial applications.     

A hybrid evolutionary algorithm for multiobjective variation tolerant logic mapping on nanoscale crossbar architectures

Nanoscale crossbar architectures have received steadily growing interests as a result of their great potential to be main building blocks in nanoelectronic circuits. However, due to the extremely small size of nanodevices and the bottom-up self-assembly nanofabrication process, considerable process variation will be an inherent vice for crossbar nanoarchitectures. In this paper, the variation tolerant logical mapping problem is treated as a bilevel multiobjective optimization problem. Since variation mapping is an NP-complete problem, a hybrid multiobjective evolutionary algorithm is designed to solve the problem adhering to a bilevel optimization framework. The lower level optimization problem, most frequently tackled, is modeled as the min–max-weight and min-weight-gap bipartite matching (MMBM) problem, and a Hungarian-based linear programming (HLP) method is proposed to solve MMBM in polynomial time. The upper level optimization problem is solved by evolutionary multiobjective optimization algorithms, where a greedy reassignment local search operator, capable of exploiting the domain knowledge and information from problem instances, is introduced to improve the efficiency of the algorithm. The numerical experiment results show the effectiveness and efficiency of proposed techniques for the variation tolerant logical mapping problem.     

Total flow time minimization in no-wait job shop using a hybrid discrete group search optimizer

The no-wait job shop scheduling problem is a well-known NP-hard problem and it is typically decomposed into timetabling subproblem and sequencing subproblem. By adopting favorable features of the group search technique, a hybrid discrete group search optimizer is proposed for finding high quality schedules in the no-wait job shops with the total flow time criterion. In order to find more promising sequences, the producer operator is designed as a destruction and construction (DC) procedure and an insertion-based local search, the scrounger operator is implemented by differential evolution scheme, and the ranger operator is designed by hybridizing best insert moves. An efficient initialization scheme based on Nawaz–Enscore–Ham (NEH) heuristic is designed to construct the initial population with both quality and diversity. A speed-up method is developed to accelerate the evaluation of the insertion neighborhood. Computational results based on well-known benchmark instances show that the proposed algorithm clearly outperforms a hybrid differential evolution algorithm and an iterated greedy algorithm. In addition, the proposed algorithm is comparable to a local search method based on optimal job insertion, especially for large-size instances.     

多智能体路径规划研究进展

多智能体路径规划是一类寻找多个智能体从起始位置到目标位置且无冲突的最优路径集合的问题,针对该问题的研究在物流、军事和安防等领域有着大量的应用场景.对国内外关于多智能体路径规划问题的研究进展进行系统整理和分类,按照结果最优性的不同,多智能体路径规划算法被分为最优算法和近似算法2类.最优的多智能体路径规划算法主要分为基于A*搜索、基于代价增长树、基于冲突搜索和基于规约的4种算法.近似的多智能体路径规划算法主要分为无边界次优的算法和有边界次优的算法2类.基于上述分类,分析各种算法的特点,介绍近年来具有代表性的研究成果,并对多智能体路径规划问题未来的研究方向进行展望.     

最大最小目标的多旅行商问题求解

研究一类多旅行商问题,对所有旅行商所走的环路,寻求最大长度最小化.设计了一种新的局部搜索算子,该算子既能进行一条环路的优化,也能对两条环路进行重组优化,与现有的局部搜索算子相比,在计算成本相当的条件下,其寻优能力更好;以该算子为基础,提出了“搜索-选优-变异-搜索”的迭代策略,按此策略设计了竞争搜索算法.在公开的数据集上进行了实验,与近期文献相比,计算结果有所改进.     

面向柔性作业车间调度的多策略鲸鱼优化算法

以某大型家具企业的柔性生产制造过程中调度问题为研究对象,提出了一种主要用于求解柔性作业车间调度问题的多策略鲸鱼优化算法(multi-strategy whale optimization algorithm, MWOA),首先,为了提高初始种群的多样性,引入混沌理论来初始化种群;同时设计了非线性收敛因子和自适应惯性权重系数来平衡全局探索和局部开发能力;然后结合差分进化(differential evolution, DE)算子提高了WOA的利用和搜索能力,最后采取最优个体混沌搜索策略,减少WOA算法出现早熟收敛现象的概率.以最小化最大完工时间为求解目标,对基准测试问题与某家具企业的生产制造过程的调度优化问题进行了求解,结果表明提出来的多策略鲸鱼优化算法克服了基本鲸鱼优化算法寻优精度低、收敛速度慢及容易陷入局部最优等缺陷,与对比算法比较,取得了更好的寻优效果.     

基于Java/XML的异构数据同步系统的设计和实现

提出一种基于发布一订阅模式的Push和Pull异构数据同步系统.该系统基于Java和XML这两种与平台无关的技术,采用了数据库触发器对数据库的变化进行捕捉,使用控制变化表来保存数据变化,并利用XML文件作为中介存储来交换变化数据,进而达到数据同步的目的.依据系统的设计,以关系型数据库SQL Server和MySQL为实例,应用Java语言进行了具体代码的实现.     

混合群体增量学习算法求解闭环布局问题

闭环布局问题（CLLP）是一种NP-困难的混合优化问题,它在大小可调的矩形环上寻找设施最佳放置次序,目标是最小化设施之间物料流的运输成本。现有方法均采用元启发式算法来寻找最优的设施放置次序,并且通过枚举方法来获得最优的矩形环大小,而枚举方法的计算效率不高。为了解决这个问题,提出了求解CLLP的混合群体增量学习（HPBIL）算法,分别使用离散群体增量学习（DPBIL）算子和连续PBIL（CPBIL）算子同时对设施放置次序和矩形环大小进行优化,提高了搜索效率;同时还设计了一个局部搜索算法来优化每代中的部分优质解,以提高算法的求精能力。在13个CLLP测试实例上进行实验,结果表明HPBIL算法在9个测试实例上找到了新的最优布局,它对CLLP的寻优能力明显优于对比算法。     

广义粒子群优化模型

粒子群优化算法提出至今一直未能有效解决的离散及组合优化问题．针对这个问题,文中首先回顾了粒子群优化算法在整数规划问题的应用以及该算法的二进制离散优化模型,并分析了其缺陷．然后,基于传统算法的速度一位移更新操作,在分析粒子群优化机理的基础上提出了广义粒子群优化模型（GPSO）,使其适用于解决离散及组合优化问题．GPSO模型本质仍然符合粒子群优化机理,但是其粒子更新策略既可根据优化问题的特点设计,也可实现与已有方法的融合．该文以旅行商问题（TSP）为例,针对遗传算法（GA）解决该问题的成功经验,使用遗传操作作为GPSO模型中的更新算子,进一步提出基于遗传操作的粒子群优化模型,并以Inverover算子作为模型中具体的遗传操作设计了基于GPSO模型的TSP算法．与采用相同遗传操作的GA比较,基于GPSO模型的算法解的质量与收敛稳定性提高,同时计算费用显著降低．     

一类动态非线性约束优化问题的新解法

动态非线性约束优化是一类复杂的动态优化问题,其求解的困难主要在于如何处理问题的约束及时间（环境）变量。给出了一类定义在离散时间（环境）空间上的动态非线性约束优化问题的新解法,从问题的约束条件出发构造了一个新的动态熵函数,利用此函数将原优化问题转化成了两个目标的动态优化问题。进一步设计了新的杂交算子和带局部搜索的变异算子,提出了一种新的多目标优化求解进化算法。通过对两个动态非线性约束优化问题的计算仿真,表明该算法是有效的。     

求解约束优化问题的佳点集多目标进化算法

结合数论中的佳点集理论和多目标优化方法,提出一种求解约束优化问题的进化算法。将约束优化问题转化为多目标优化问题,引入佳点集理论,以确保所构造的个体在搜索空间内分布均匀,设计变异算子增加个体多样性,采用分群局部搜索方式,并根据Pareto非支配关系选择群体中的优势个体。实验结果表明,该算法具有较好的稳定性。     

用PHP实现Web页面无闪动刷新

介绍了PHP技术的优点及其应用前景以及页面刷新的两种技术：Client Pull和Server Push,详细阐述了利用PHP技术实现Web页面无闪动刷新的技术。