An Algorithm for Solving Generalized Single Row Facility Layout Problem

Layout design problem is to determine a suitable arrangement for the departments so that the total costs associated with the flow among departments become least. Single Row Facility Layout Problem, SRFLP, is one of the layout problems that have many practical applications. This problem and its specific scenarios are often used to model many of the raised issues in the field of facility location. SRFLP is an arrangement of n departments with a specified length in a straight line so that the sum of the weighted distances between the pairs of departments is minimized. This problem is NP-hard. In this paper, first, a lower bound for a special case of SRFLP is presented. Then, a general case of SRFLP is presented in which some new and real assumptions are added to generate more practical model. Then a lower bound, as well as an algorithm, is proposed for solving the model. Experimental results on some instances in literature show the efficiency of our algorithm.

Layout problem of multi-component systems arising for improving maintainability

To improve the maintainability design efficiency and quality,a layout optimization method for maintainability of multi-component systems was proposed.The impact of the component layout design on system maintainability was analyzed,and the layout problem for maintainability was presented.It was formulated as an optimization problem,where maintainability,layout space and distance requirement were formulated as objective functions.A multi-objective particle swarm optimization algorithm,in which the constrained-domination relationship and the update strategy of the global best were simply modified,was then used to obtain Pareto optimal solutions for the maintainability layout design problem.Finally,application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method.The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.

Ant Colony System for a Fuzzy Adjacent Multiple-Level Warehouse Layout Problem

A warehouse layout problem where the warehouse has more than one level and both the distance from the cell to the receive/exit bay and demand of item types are fuzzy variables is proposed. The problem is to find a layout with the minimum transportation cost subject to adjacency and other constraints. A fuzzy expected value model is given and an ant colony system is designed to solve the problem. Computational results indicate the efficiency and effectiveness of the method.

Integrated optimal method for cell formation and layout problems based on hybrid SA algorithm with fuzzy simulation

To adapt to the complex and changeable market environment,the cell formation problems(CFPs) and the cell layout problems(CLPs) with fuzzy demands were optimized simultaneously. Firstly,CFPs and CLPs were described formally. To deal with the uncertainty fuzzy parameters brought,a chance constraint was introduced. A mathematical model was established with an objective function of minimizing intra-cell and inter-cell material handling cost. As the chance constraint of this problem could not be converted into its crisp equivalent,a hybrid simulated annealing(HSA) based on fuzzy simulation was put forward. Finally,simulation experiments were conducted under different confidence levels. Results indicated that the proposed hybrid algorithm was feasible and effective.

Pod Layout Problem in Kiva Mobile Fulfillment System Using Synchronized Zoning

This article studies the pod layout problem in the Kiva mobile fulfillment system which adopts the synchronized zoning strategy. An integer programming model for the pod layout problem is formulated under the premise of knowing the relationship of the pods and items. A three-stage algorithm is proposed based on the Spectral Clustering algorithm. Firstly, the pod similarity matrix and the Laplacian matrix are constructed according to the relationship of the pods and items. Secondly, the pods are clustered by the Spectral Clustering algorithm and assigned to each zone based on the cluster results. Finally, the exact locations of pods in each zone are determined by the historical retrieval frequency of items, using the real data of a large-scale Kiva mobile fulfillment system to simulate and calculate the order picking efficiency before and after the adjustment of the pod layout. The results showed that the pod layout using synchronized zoning strategy can effectively improve the picking efficiency.

A Mixed-Integer Programming Formulation for a Simplified Model of the Double Row Layout Problem

The double row layout problem(DRLP)is to assign facilities on two rows in parallel so that the total cost of material handling among facilities is minimized.Since it is vital to save cost and enhance productivity,the DRLP plays an important role in many application fields.Nevertheless,it is very hard to handle the DRLP because of its complex model.In this paper,we consider a new simplified model for the DRLP(SM-DRLP)and provide a mixed integer programming(MIP)formulation for it.The continuous decision variables of the DRLP are divided into two parts:start points of double rows and adjustable clearances between adjacent facilities.The former one is considered in the new simplified model for the DRLP with the purpose of maintaining solution quality,while the latter one is not taken into account with the purpose of reducing computational time.To evaluate its performance,our SM-DRLP is compared with the model of a general DRLP and the model of another simplified DRLP.The experimental results show the efficiency of our proposed model.

An extended discrete particle swarm optimization algorithm for the dynamic facility layout problem

We extended an improved version of the discrete particle swarm optimization (DPSO) algorithm proposed by Liao et al.(2007) to solve the dynamic facility layout problem (DFLP). A computational study was performed with the existing heuristic algorithms, including the dynamic programming (DP), genetic algorithm (GA), simulated annealing (SA), hybrid ant system (HAS), hybrid simulated annealing (SA-EG), hybrid genetic algorithms (NLGA and CONGA). The proposed DPSO algorithm, SA, HAS, GA, DP, SA-EG, NLGA, and CONGA obtained the best solutions for 33, 24, 20, 10, 12, 20, 5, and 2 of the 48 problems from (Balakrishnan and Cheng, 2000), respectively. These results show that the DPSO is very effective in dealing with the DFLP. The extended DPSO also has very good computational efficiency when the problem size increases.

FUZZY MULTI-LEVEL WAREHOUSE LAYOUT PROBLEM:NEW MODEL AND ALGORITHM

This paper deals with a multi-level warehouse layout problem under fuzzy environment, in which different types of items need to be placed in a multi-level warehouse and the monthly demand of each item type and horizontal distance traveled by clamp track are treated as fuzzy variables. In order to minimize the total transportation cost, chance-constrained programming model is designed for the problem based on the credibility measure and then tabu search algorithm based on the fuzzy simulation is designed to solve the model. Some mathematical properties of the model are also discussed when the fuzzy variables are interval fuzzy numbers or trapezoidal fuzzy numbers. Finally, a numerical example is presented to show the efficiency of the algorithm.

眼前山铁矿采区稳定性微震监测可行性研究

文章介绍了眼前山铁矿工程背景及回采过程中面临的地压问题,结合多通道微震监测技术特点,制定了覆盖采区的48通道微震监测系统技术方案。采用D值最优设计理论,对传感器进行了优化布置,确定的采区微震监测技术方案可实现回采过程中采区稳定性实时、在线和全方位立体监测,为采区安全回采提供技术支撑。

Analysis of problems in urban green space system planning in China

这篇论文在在中国在一般、特殊的计划层次计划的城市的绿空间系统(UGSS ) 讨论主要问题。在一般计划水平， UGSS 的问题主要从在城市的性质空格的特征和城市的计划系统的限制因素的无知。大重要性在包围城市的区域在城市，而是绿空格的造的区域被纳入绿空格是不被注意的。而且，因为 UGSS 计划的区域被行政 zoning 严格地限制，绿空格系统在空间模式失去它的完整和合理性。城市的开发计划的时间表错配生态的恢复周期的步和进步。在特殊计划水平，在中国的 UGSS 的问题是空格数量是完了的绿色强调了，但是他们的布局的合理性被忽视……同时，空间结构的要求和到在城市的发展和自然生态的环境之间的平衡的绿空格布局经常被忽略。关于在计划惯例的 UGSS 的布局，存在问题是妥协到存在陆地使用，布局模式的计划绿空格的‘ f illing in' 途径和一个过分的强调。

矩形布局优化问题的局部搜索蜂群算法

带平衡约束的矩形布局问题属于组合优化问题,当问题规模增大时求解困难。为提高求解效率,设计了一个蜂群算法,通过分析解的分布,提供了基于贪心策略的群体初始化方案,选择了有效的变异算子,将蜂群算法的搜索空间聚焦于最优解可能的区域。另外设计了一个二次局部搜索算法,对解的质量进行进一步提升。在10个公开的案例上与目前性能最好的算法进行了对照,提出的蜂群算法在其中9个较大规模的案例上超过了现有算法。理论分析和实验结果表明,相对于现有算法,所提蜂群算法能明显提高求解效率。

具有安全间隙及物料装卸点的多行布局问题建模与优化

针对当前多行布局研究中忽略设施安全间隙及假定物料装卸点重合的不足,结合实际布局情况,提出了具有安全间隙及物料装卸点的多行布局问题。以物流成本和布局面积为优化目标,构建了混合整数规划模型,并运用Gurobi对小规模算例进行了精确求解。结合问题特点,设计了一种融合生物地理学算法和线性规划的两阶段方法,通过分阶段迁移、反向学习机制、自适应变异、局部搜索等操作对原始算法进行改进,并采用双阈值停止准则,去除冗余循环次数。运用该算法求解规模为5~49的若干标准算例,结果对比验证了算法的高效性和稳定性。最后应用所提算法求解实际车间布局问题,经数据比对,进一步验证了算法在求解质量上的优越性。

石津干渠增设清污设备布置方案探讨

石津干渠的下级配套输水工程均为管道输水,管道中设置调流阀、排气阀,为防止调流阀、排气阀堵塞,保证管道输水正常运行,在管道前端设置滤网清污设施。运行多年,发现由于上游未设清污设备导致沧州压力箱涵进口及傅家庄泵站运行存在人工出渣劳动强度大、工作条件艰苦,亟需改造出渣方式及旋转滤网需不间断运行,倘若故障停运会迅速壅高上游渠道水位,影响渠道运行安全等问题。对于污物较多、滤网间断运行问题,可通过在明渠分段拦截清污和增设并联清污设施解决。目前,明渠段大田南干及七分干已增设清污机,树叶、小鱼、塑料包装袋等污物大部分可清除,减轻下游清污压力,下游泵站及管道上调流阀不再频繁淤堵;另外,根据滤网连续运行时的上下游水位差看,清污机有效工作情况下水头损失一般在10 cm以下,多处于4~7 cm之间,低于设计计算值,运行状况良好。后续在持续增设其他清污闸情况下可以彻底提升明渠段水质,打造一流供水渠道。

中国海上风电产业布局研究

中国海上风电产业面临未来短期开发建设速度的调整和中长期巨大潜在需求的释放,海上风电产业布局优化与能力提升成为热点论题。总结了当前海上风电产业发展现状,基于产业布局理论,梳理了山东省和东南沿海省份的海上风电产业环境条件,并采用层次分析法对海上风电产业布局的优劣进行了对比分析,得出海上风电产业面临空间布局不合理、发展不均衡、存在明显短板弱项等问题。最后,提出了优化项目开发模式与规划管理、促进产业合理布局与良性发展、加强技术研发创新与推广应用的政策建议。

利用命题逻辑最大可满足性的冗余通孔最优插入方法

在纳米尺度的集成电路设计中,冗余通孔插入是减轻通孔失效造成良率降低问题的常用技术.文中将最优冗余通孔插入问题规约到命题逻辑最大逻辑可满足性(maximum satisfiability,Max SAT)问题,并利用完备求解器求取最优解.Max SAT问题是一个NP困难问题,采用2种方法来降低求解难度;一是预选取方法,将提前确定的不与其他通孔产生冲突的冗余通孔作为部分解来降低问题的规模;二是分治法,根据连通分量将原问题划分成多个子问题分别求解,降低求解的复杂度.同时,从理论上证明这2种方法能够保证解的最优性.在2019年国际物理设计研讨会(ISPD)举办的详细布线比赛基准测试集上进行实验的结果表明,所提出的插入方法带来的时间开销不到详细布线时间的5%,算法的最优性保证了最大化解决插入冲突后的插入率,在所有可插入通孔中,冗余通孔的插入率为67%~87%.

考虑冗余的极小碰集问题研究

针对海上采油平台可燃气体探测器布设优化问题,首先建立了一个精确理论模型;通过对精确理论模型进行降维、简化和数字化处理,得到一个近似应用模型,该模型可视为极小碰集问题的一个变体,即考虑冗余的极小碰集问题。证明了冗余度大于或等于2的极小碰集问题都是NP-完备的。结合探测器布设的应用背景,针对冗余度为2的问题设计了一个启发式算法,旨在保证冗余度的前提下,极小化所需探测器的数目。仿真结果表明,该算法可以在不显著增加或减少探测器安装数目的情况下,使得任何一个拟泄漏点在任何风向下发生泄漏,都可以至少被两个探测器探测到,从而大大提高平台的安全性。

缺陷板材二维排样的一种随机密钥遗传算法

讨论缺陷板材二维排样问题,即用一张带缺陷区域的板材切割出若干种矩形件,对每种矩形件允许从板材上切割的数量不做限制,优化目标为板材切割出的矩形件的总价值最大.将放置规则和随机密钥遗传算法相结合求解排样方式,用放置规则确定当前待排样矩形件在板材上的放置位置,用随机密钥遗传算法确定矩形件的排样序列和排样参数,用极大空闲空间技术处理板材的空闲空间和缺陷区域.为了提高遗传算法对解空间的搜索范围,放置规则采用最下最左和最左最下两种不同的启发式.通过数值实验比较所提方法与文献方法,实验结果表明,所提方法计算时间较少、排样价值较高.

云南水富港扩能工程总体布局设计要点

针对山区河流水流条件复杂、陆域纵深狭窄、港口布局受限的问题,提出可行的解决方案,采取相应工程措施,实现港区“铁、公、水”联运功能;并针对水域布置的关键问题,通过物理模型试验,优化平面布置,改善通航条件。营运期验证表明,码头泊位前沿水流平缓、流态稳定,船舶装卸作业可靠度较高,技术路线和研究方法合理可行。

群塔平面优化布置问题的数学建模与求解

群塔平面布置是一个典型的工程优化问题。本文从工程施工的实践角度出发,对工程设计和施工人员所提出的群塔平面优化问题进行了深入分析,明确了塔吊平面布置问题的目标函数除了考虑塔吊租金之外,还应当考虑施工区域未覆盖和重复覆盖的影响,利用罚函数实现了多个目标的组合。对设计变量和约束条件都进行了归一化处理。对于所建立的优化数学模型,采用了具备本质并行性、全局收敛性的智能优化算法进行了求解。最后,利用本文所建立的方法对一个实际工程的群塔平面优化布置问题进行了分析求解,分别给出了塔吊数量为5、6、7时的最优布置方案,并根据工程的实际状况进行了分析。数值算例表明,本文所提出的方法具备可用性和有效性,能够解决一般的群塔平面优化布置问题。

城市集中供热管网中存在的问题及优化设计

随着我国城市化建设的加快,对供热管网结构的要求也越来越高。枝状管网作为集中供热管网的主要形式之一,具有造价低廉、运行与管理较为简单等优势,在城市建设中得到了有效应用。但是该管网在长时间应用中,会出现局.部故障,影响供热的效果。为了进一步提高集中供热管网运行的效果,对其中的问题进行了分析,并提出优化措施,希望能够为相关学者提供借鉴价值。