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.

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.

Research on Cell Manufacturing Facility Layout Problem Based on Improved NSGA-II

With the rapid development of the individualized demand market,the demand for manufacturing flexibility has increased over time.As a result,a cell manufacturing system suitable for many varieties and small batches has been produced.With the goal of minimizing the area and logistics handling volume,and considering the arrangement order of facilities and channel constraints,a mathematical model was established,and the problem was solved by improved NSGA-II.After non-dominated sorting,traditional NSGA-II will cross-operate the individuals with the best sorting to generate new individuals.Such a selection strategy is extremely easy to fall into the local optimal solution.The improved NSGA-II is to improve the original selection operation,which is to select the first half of the excellent individuals in the non-dominated sorting into the cross operation,and then select the last sorted ones of the remaining individuals into the cross operation,and combine the best and the worst ones into the cross operation.Finally,an example is given to simulate and improve the solution of NSGA-II and NSGA-II.The simulation results indicate that the improved NSGA-II population shows more obvious diversity,it is easier to jump out of the local optimal solution than NSGA-II,and the satisfactory layout scheme of manufacturing cells is obtained.Therefore,it is more effective to use improved NSGA-II to solve the problem of manufacturing cell layout.

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.

Current Research Situations,Problems and Recommendations of Land Use Structure and Layout Optimization

Land is the foundation for human survival and development,and all human social and economic activities are inseparable from the land as a space carrier.With the continuous development of China's social economy,China is facing new social development needs such as urban-rural integration and rural revitalization.At the same time,China starts to attach great importance to ecology and has proposed the concept that lucid waters and lush mountains are invaluable assets.In this situation,the rational use of land resources,the optimization of land use structure and layout are also facing new challenges and problems,and more comprehensive consideration is required to make relevant optimization.Using the method of literature comparative analysis,from the conceptual connotation,basic theory,method model,and specific practice of land use structure and layout optimization,this paper analyzed and summarized the current research situations and problems,and finally came up with recommendations for the future research.

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。

四川省抽水蓄能发展思考和总结

四川省发展抽水蓄能以多元开发保障电力供应。结合近几年四川省抽水蓄能规划设计经验,系统阐述了在负荷持续刚性增长背景下,四川省抽水蓄能作为重要的多能互补电源,从双碳目标下能源电力保供、满足负荷中心调峰、促进风光新能源开发等方面的开发必要性。考虑到四川省源荷异地特点下,四川省不同抽水蓄能发挥的功能和作用不同,应在新能源集中区域和靠近负荷中心合理布局,提出了四川省抽水蓄能的开发方式,根据需求和工程实际情况,可因地制宜发展适度规模的混合式抽水蓄能和中小型抽水蓄能。同时,详细总结了四川省抽水蓄能前期工作和开发建设中需要关注的重要关键技术问题,如识别移民环保敏感对象、水文泥沙措施可行经济、复杂地质条件可行、已有工程结合影响、高海拔机电设备适应性等。结合工作经验,提出了四川省抽水蓄能发展建议。

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.

快速通道衔接匝道布局优化与适应性分析

快速通道是指能够实现快速运输的交通系统,它常因瓶颈路段而影响车辆的快速通行。快速通道的匝道布局方案优化设计是减少瓶颈路段产生的重要手段,但目前缺乏定量精细化布局优化方法,同时也难以评估衔接匝道布局方案是否能够适应未来的流量变化。为解决这个问题,提出了一种快速通道衔接匝道布局优化设计方法体系。考虑车流的连续性、快速通道的高效性、地面道路的通畅性、整体通道的流量均衡性与衔接匝道的经济性等因素,以通道内所有车辆通行时间最短为目标,建立了快速通道匝道衔接布局优化模型,并利用遗传算法求解得出不同情形下的最优方案。针对通道系统、快速通道路段和地面出口路段构建了3个适应性评价指标,对最优方案通道应对交通不确定性需求的弹性能力进行了综合评价,为分析通道应对不确定性需求提供了一种方法。以假设广州-深圳高速公路修建上垮桥和地面辅道方案为例,验证了该优化方法的适用性。结果表明:此方法能定量确定不同约束条件下衔接通道的修建个数、位置和匝道车道数,并有效减少因衔接不当和需求不确定性耦合而产生的瓶颈路段,保证了快速通道的高效通行,完善了在设计阶段以衔接匝道布局优化解决快速通道拥挤问题的方法体系。

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。

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。

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。

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。

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%.

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.

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。

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。