Layout problem of multi-component systems arising for improving maintainability

To improve the mainlainability 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.

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.

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.

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.

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.

Analysis of problems in urban green space system planning in China

This paper discusses the major problems in urban green space system （UGSS） planning at both general and special planning levels in China. At general planning level, the problems of the UGSS are mainly from the ignorance in the characteristics of urban nature spaces and the limitation factors of the urban planning system. Great importance is attached to the green spaces in the built area of city, but the green spaces in surrounding areas of the city is unnoticed. Furthermore, because the area of UGSS planning is strictly limited by the administrative zoning, the green space system loses its integrity and rationality in spatial patterns. The schedules of urban development planning mismatched the paces and progresses of the ecological restoration cycles. At special plan level, the problem of the UGSS in China is that the green spaces quantity was over emphasized but the rationality of their layouts is neglected.. Meanwhile, the requirement of the spatial structures and the green spaces layouts to balance between the urban development and the natural ecological environments is often ignored. With regard to the layouts in the UGSS planning practices, the existing problems are the compromising to the existing land-uses, the ＇filling in＇ approach to plan green spaces and an over-emphasis on the layout patterns.

大城市工业用地布局演变中的城市问题研究——以西安市为例

改革开放以来在我国经济转型过程中大城市工业用地的规模和布局发生了巨大变化,并影响城市的空间形态。以西安市为例,基于多源数据,采用定量与定性相结合方法,研究发现1974—2019年西安市工业用地面积呈先持续增长后快速减少变化趋势,空间布局在园区化集聚的过程中具有显著的工业用地郊区化与城市中心用地去工业化特征,布局模式则经历了由改革开放初期“组团布局+扇形扩展”向增量规划时期“圈层扩展+跳跃扩张+轴向集聚”至存量规划时期“外围园区化集聚”转变。帮助企业纾困、城市增长、生活居住条件改善与土地经济价值是推动工业用地布局演变的主要驱动力。工业用地郊区化与城市中心去工业化加剧了职住分离、交通拥堵等城市问题,不利于城市健康可持续发展。

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。

长江江苏段岸线利用与港口布局

长江江苏段拥有全长约８３７ｋｍ的干流岸线资源，至１９９７年底，实际利用率超过１７％，位居沿江各省市之首。但同时也存在岸线利用缺乏统一的规划管理，造成部门与部门、地方与部门以及地方与地方之间存在矛盾、港口码头建设政出多门，布点过多、能力过大与结构雷同的重复建设现象突出和重大岸线开发工程缺乏足够的科学论证、带有一定的盲目与随意性等亟待解决的重大问题。因此，尽快制定权威的岸线功能区划和开发利用规划、建立由省一级政府计划综合部门扎口审批的岸线占用项目管理制度和跨部门、跨地区的港口建设和营运体系，并实行岸线有偿使用等，是解决上述问题的有效途径。

一种结合多目标免疫算法和线性规划的双行设备布局方法

设备布局对于提高生产效率和降低运营成本具有重要意义.本文针对半导体加工制造中常见的双行设备布局问题,提出了一种结合多目标免疫算法和线性规划的双行设备布局方法来同时优化物料流成本和布局面积两个目标.首先,建立了问题的混合整数规划模型;其次,针对问题既含有组合方面(机器排序)又含有连续方面(机器精确位置)的特点,分别设计了一种多目标免疫算法来获取非支配的机器排序集合,提出了一种基于线性规划的方法来构造任一非支配机器排序对应的连续的非支配解集;最后,由所有连续的非支配解来构造最后Pareto解.实验结果表明,该方法对于小规模问题能获得最优Pareto解,对于大规模问题能够获得具有良好分布性的Pareto解且其质量远好于NSGA-II和精确算法获得的解.

求解单行布局问题的一种变邻域搜索算法

设施布局问题对于企业内部的物流合理化起着重要作用,单行布局问题作为设施布局问题的一个典型特例,属NP-hard问题,常规方法难以精确求解。针对单行布局问题的复杂性,提出了一种改进的变邻域搜索算法进行求解。首先构建单行布局问题的数学模型,然后分析模型并构造一种有效的初始解;针对问题特征,设计了4种邻域结构,该邻域结构采用了从简单到复杂的推进搜索机制;改进了局部搜索算法并对邻域结构进行搜索;最后进行了实例验证,并与多种经典算法进行了对比,结果表明,所提变邻域搜索算法可在短时间内得到单行布局问题高质量的近优解。

改进的实数编码遗传算法在产品布局设计中的应用

为求解复杂结构产品的布局设计问题,对实数编码遗传算法进行了改进,直接将问题的求解变量作为染色体基因进行编码,提出了一种解空间编码遗传算法。在求解问题前,对布局问题进行了预处理。在求解过程中,首先引入模拟退火算法的思想对解进行选择;然后对不同类型变量采用不同的交叉和变异算子进行了处理,并在变异前对个体的连续变量随机加一个扰动量,以控制其搜索范围;最后对求解的中间结果按最优保留策略进行了处理。该算法实现了3维空间布局规划的自动寻优,并求解了2维和3维带性能约束的布局问题,验证了该算法的可行性和有效性。

基于指派问题的Bay位排箱优化模型与算法

提出了解决集装箱船全航线配载问题的分解算法,将配载问题分解为Bay位选择和Bay位中集装箱箱位指定两个子问题.主要研究了Bay位中装载同一目的港集装箱时,不同重量集装箱在Bay位中的排箱方法.以重心高度最低、横倾力矩最小为目标建立优化模型,将Bay位中不同重量集装箱排箱问题看成是箱位指派问题,采用禁忌搜索算法求解.实际模拟结果表明该方法可行,为集装箱船全航线配载优化提供了一个实用的优化模型.

双行布局问题的分解策略及启发式求解方法

为克服现有方法在求解大规模双行布局问题时存在的计算时间长、性能不稳定等问题,提出了结合问题特征的分解策略,将大规模双行布局问题分解为较易求解的组合优化问题与线性规划问题两个子问题,并分别建立了相应的数学模型.提出了3种基于不同优先规则的启发式求解方法,该方法的特征是机器成对分配,且结合了线性规划法.对大量不同规模（6～36台机器）的测试问题进行了验算与对比.试验结果表明,所提启发式方法尤其是其中的heuristic3启发式方法,能快速有效地求解双行布局问题,与现有方法相比,在运行效率和求解偏差上具有优势.

一种基于遗传算法的工艺品布局求解算法

在组件特征模型的基础上 ,针对工艺品布局创新的需要提出亚组件的概念 ,在遗传算法中引入人机交互技术 ,在适合度函数中引入形象度和抽象度 ,形成一种基于遗传算法的布局自动求解算法 .以斑铜工艺品布局求解为例 ,对该算法进行了验证 .理论和实例分析表明 ,该算法能快速有效地生成多个斑铜工艺品的布局方案 .

基于粒度分层的布局设计模型

研究了问题求解的粒度理论在布局建模中的应用 .综合相邻图、规范约束图以及层次约束图模型为不同粒度的组成部分 ,提出了基于粒度分层的布局模型和粒度投影规则方法 .该模型能够克服单一粒度模型难以充分表达约束、求解时搜索量大等不足 .在粒度世界的结构非拓扑且非半序的情况下 ,由投影规则可建立不同粒度世界间的联系 ,使不同粒度世界上的结构及约束信息能够有效转换 。

物流系统规划设计方法综述

综合分析了物流系统规划设计方法中的若干关键问题。主要包括在布局设计方面的数学模型和计算机辅助设施布局算法、选址—分派问题上的研究状况分类、车辆—路径方面的模型和算法以及在选址—路径问题上的模型和算法的系统归纳和整理。