A cutting plane algorithm for the site layout planning problem with travel barriers

Site layout planning is an imperative procedure that may significantly impact the productivity and the efficiency of logistical operations undertaken on a construction site. This paper considers the site layout planning problem (SLPP) which entails the allocation of temporary facilities on a construction site in the presence of travel barriers such that the total transportation cost between facilities is minimised. In order to account for travel barriers, the SLPP is typically solved under the assumption that the available region for facility layout can be discretised. In this paper, we propose a general Mixed Integer Programming (MIP) model to represent the SLPP, accounting for the presence of barriers, and we show how space-discretised formulations can be derived from this model. In particular, we propose a novel MIP model, which permits facilities to cover multiple locations. This is then benchmarked against a commonly adopted MIP model in the literature. We also highlight a systematic procedure to convert the continuous feasible space in SLPP to a set of discretised locations based on the concept of d-visibility, enabling us to approximate the barrier distance function embedded in the objective function. In particular, we focus on presenting a simple space discretisation approach for converting the continuous SLP into a discrete problem for which the discrete SLP models would be applicable. Space-discretised MIP formulations are highly combinatorial and we introduce a cutting plane algorithm to improve their tractability. Specifically, we propose a novel exact location-decomposition algorithm which works from a relaxed MIP formulation and iteratively generates feasibility cuts to converge to an optimal solution. Both space-discretised MIP models and the decomposition algorithm are tested on a large group of instances to analyse their effectiveness in solving the SLPP. Computational results indicate that the proposed location-decomposition algorithm improves on the pure MIP approach and provides a competitive framework to solve realistic SLPP instances.     

Towards measuring the effectiveness of a facilities layout

Performance measurement models are essential to support various decision making problems that may arise during life cycle of a facilities layout. Available models are only suitable for early stages in the design phase of life cycle. However, measurement models have a great consequence in other phases also such as production planning, control and when modification to be incorporated due to the changes in market demand, which happens very often in today's global competition. In addition, the existing models have considered only material handling cost as the performance measurement factor. Nevertheless, the empty travel of material handling equipment, layout flexibility and area utilisation have a significant contribution towards the layout effectiveness. It is therefore necessary to have a measurement model to determine the facilities layout's effectiveness by considering all significant factors. A measurement model considering a set of three layout effectiveness factors—facilities layout flexibility (FLF), productive area utilisation (PAU) and closeness gap (CG)—is developed in our research. The proposed model will enable the decision-maker of a manufacturing enterprise to analyse a layout in three different aspects, based on which they can make decision towards productivity improvement. This paper mainly discusses about the measurement of the CG. The CG is developed with respect to the objective of bringing closer the highly interactive facilities/departments. The CG presented in this paper extends other related works by incorporating numerous aspects of layout that include empty travel of material handling equipment, information flow, personnel flow and equipment flow.     

Solving an extended multi-row facility layout problem with fuzzy clearances using GA

Multi-row facility layout problem (MRFLP) is a class of facility layout problems, which decides upon the arrangement of facilities in some fixed numbers of rows in order to minimize material handling cost. Nowadays, according to the new layout requirements, the facility layout problems (FLPs) have many applications such as hospital layout, construction site layout planning and layout of logistics facilities. Therefore, we study an extended MRFLP, as a novel layout problem, with the following main assumptions: 1) the facilities are arranged in a two-dimensional area and without splitter rows, 2) multiple products are available, 3) distance between each pair of facilities, due to inaccurate and flexible manufacturing processes and other limitations (such as WIPs, industrial instruments, transportation lines and etc.), is considered as fuzzy number, and 4) the objective function is considered as minimizing the material handling and lost opportunity costs. To model these assumptions, a nonlinear mixed-integer programming model with fuzzy constraints is presented and then converted to a linear mixed-integer programming model. Since the developed model is an NP-hard problem, a genetic algorithm approach is suggested to find the best solutions with a minimum cost function. Additionally, three different crossover methods are compared in the proposed genetic algorithm and finally, a sensitivity analysis is performed to discuss important parameters.     

Planning facilities layout in clinical laboratories using a group decision making process

A group decision making process used for planning the facilities layout in clinical laboratories is described. While quantitative and computer-based models can be used for planning alternative layout plans, considerations of qualitative and personal factors should be given during the layout finalization phase. The visual evaluation of detailed architectural drawings of alternative layout plans, by a group of the laboratory employees, can result in generating ideas for modifications. These modifications are incorporated in a new plan. The process of evaluation of a modified plan, generating ideas for further improvements, and readjusting the layout plan would result in an effective laboratory layout. This can increase employee morale and productivity. The group decision making process was successfully applied to redesigning the facility layout in a hospital clinical laboratory.     

考虑交通流量的改进型电动汽车充/换电设施选址布局

为了有效促进电动汽车在我国的蓬勃发展、提高电动汽车使用效能并降低交通物流业的环境污染,本文拟通过构建考虑交通流量的电动汽车充/换电设施规划方法进行电动汽车充/换电设施优化布局研究。首先,从便利性原则、经济性原则、安全性原则、可行性原则4个方面分析电动汽车充/换电设施的布局原则;在此基础上,综合分析典型选址模型的局限性,以充/换电设施的服务能力最大化为目标,构建考虑交通流量的改进型电动汽车充/换电设施截流选址模型;然后,考虑到该模型的NP-hard特性,将二进制粒子群算法引入充/换电设施的布局模型求解中以提高计算效率;最后,以深圳市某区域为实例,基于MATLAB软件进行电动汽车充/换电设施规划布局研究,为该区域充/换电设施布局提供行之有效的方案。     

A dynamic multi-objective approach for the reconfigurable multi-facility layout problem

The multi-facility layout problem involves the physical organization of departments inside several facilities, to allow flexible and efficient operations. This work studies the facility layout problem in a new perspective, considering a group of facilities, and two different concerns: the location of departments within a group of facilities, and the location of departments inside each facility itself. The problem is formulated as a Quadratic Programming Problem with multiple objectives and unequal areas, allowing layout reconfigurations in each planning period. The objectives of the model are: the minimization of costs (material handling inside facilities and between facilities, and re-layout); the maximization of adjacency between departments; and the minimization of the “unsuitability” of department positions and locations. This unsuitability measure is a new objective proposed in this work, to combine the characteristics of existing locations with the requirements of departments. The model was tested with data from the literature as well as with a problem inspired in a first tier supplier in the automotive industry. Preliminary results show that this work can be viewed as an innovative and promising integrated approach for tackling real, complex facility layout problems.     

考虑多重覆盖的应急设施多级协同布局鲁棒优化

应急设施的合理布局是灾后实现物资高效、公平和稳定供应的重要保障.针对突发自然灾害的不确定性,研究基于多重覆盖的应急设施多级协同布局鲁棒优化问题.首先,提出多级设施选址下的多重覆盖水平函数,以最小覆盖水平和期望总成本最优为目标,建立应急设施多级协同选址双目标优化模型;其次,应用基数不确定集和p-鲁棒方法构建两类鲁棒优化模型,分别研究场景内不确定需求和随机场景对设施布局的影响;最后,以湖南省救灾备荒种子储备库选址为例进行实证分析,验证所提出优化模型的有效性.研究结果表明:多级协同布局相比传统布局方案更具优势;鲁棒优化模型能够有效应对不确定情形和随机场景下的物资需求;决策者的风险偏好程度和预算水平对设施协同布局有重要影响,需对二者进行综合权衡.     

轨道交通车站乘客集散系统Anylogic仿真优化

为了研究地铁轨道交通车站站台乘客行为的特殊性对地铁轨道交通车站设施设备布局的影响,本文运用基于社会力模型算法的Anylogic动态仿真软件构建了面向复杂交织乘客行人流的地铁轨道交通站台场景模型。以某市地铁轨道交通车站为例对该模型进行了校核与验证,针对地铁车站内的设施设备布局的缺陷提出了优化改进措施。实证研究表明:优化后的地铁轨道交通站台场景模型,能够科学合理地阐述客流组织与地铁轨道交通之间的动态关系,同时对其他地铁轨道交通车站的规划设计与运营具有重要的借鉴与指导意义。     

空间布局的约束图方法

空间布局的自动化是智能CAD领域的研究方向之一,旨在为设计师提供智能辅助工具，用于求解在建筑、厂房设备、大规模集成电路以及产品包装等等若干领域出现的布局问题.图论方法是空间布局研究的主要途径之一.以往的布局模型由于难以充分表达知识与约束,使得设计过程与结果难以控制.本文提出一种可应用于2D及3D布局的规范约束图及层次约束图模型,给出了约束图解的存在条件.该模型可以表示精细的布局知识与约束,在一定程度上克服了以往图模型不能充分表达布局知识与约束的不足.本文还给出了基于约束图的布局生成算法.     

Siting park-and-ride facilities using a multi-objective spatial optimization model

Park-and-ride services are an important component of many public transportation systems in the United States. Locating park-and-ride facilities is an essential step when planning for these services. In this research we focus on three major siting/modeling concerns that need to be addressed when siting park-and-ride facilities: covering as much potential demand as possible, locating park-and-ride facilities as close as possible to major roadways, and siting such facilities in the context of an existing system. Unfortunately, existing models do not enable each of these concerns to be simultaneously addressed. This paper presents a multi-objective spatial optimization model for integrating these considerations. This model is applied for siting park-and-ride facilities in Columbus, Ohio. Application results show the usefulness of the developed model in supporting transit planning in an urban region.     

A new intelligent algorithm for dynamic facility layout problem in state of fuzzy constraints

In the present paper, the dynamic facilities layout problem is studied in presence of ambiguity of information flow. Product demand (and consequently material flow) is defined as fuzzy numbers with different membership functions. The problem is modeled in fuzzy programming. Three models of expected value, chance-constrained programming and dependent-chance programming and two hybrid intelligent algorithms are then presented. At the end, efficiency of algorithms for solving fuzzy models of dynamic facilities layout is shown through some numerical examples.     

基于Wang-Landau算法的动态设施布局方法

动态设施布局问题是设施在车间内多个阶段的布局规划问题。目前,针对动态设施布局问题,国内外学者对离散模型研究较多,而对连续模型的研究却较少。根据连续动态设施布局的特性与需求,构建了不等面积设施的动态设施布局连续模型。求解该模型的难点在于缺乏一种高效的布局优化方法。Wang-Landau算法是一种改进的蒙特卡罗算法。通过将Wang-Landau算法与空位点放置策略、外推移动策略、内压移动策略三种启发式策略相结合,提出一种基于Wang-Landau抽样的启发式算法,并以此求解该模型。使用文献中已有的测试算例对提出的算法进行测试,计算结果表明,所提出的算法在求解连续动态设施布局问题上是有效的。     

面向手机3D动画自动生成的空间分层布局规划

手机3D动画自动生成系统是将用户发送的短信,经过信息抽取、情节规划等一系列的处理,最终生成一段与短信内容相关的三维动画并发送给接收方这一过程.布局规划是系统的一个重要组成部分,其功能是将模型放置到场景的可用空间上.通过对布局问题的研究,本文提出了一种基于区域布局和模型布局的分层布局方法,其包括定性规划和定量计算两个部分,利用语义网技术建立分层布局知识库,基于规则的方法推导出分层布局定性规划方案,并对模型位置进行动态计算.最后,通过实验验证了分层布局规划的有效性和多样性,满足了自动生成系统对布局规划的要求.     

Interactive microcomputer graphic methods for smoothing craft layouts

Computer-aided layout planning has been under development since the early 1960s, and many layout programs are based on the powerful and well known program, CRAFT (Computerized Relative Allocation of Facilities Technique by Armour and Buffa 1963).

Unfortunately, the major drawback of these facilities layout programs is that they often create unrealistic and impractical designs since the resulting block layouts can have odd shapes. Most architectural building designs require that the rooms and departments be in the form of squares, rectangles or L-shapes. The traditional approach to rectifying this problem is to manually modify the block plans at the corresponding expense of time and effort.

This paper identifies the problems and proposes interactive graphic methods for smoothing CRAFT layouts. In addition, a new method for the assessment of layout efficiency is introduced to measure the quality of a layout before and after smoothing.     

An improved genetic algorithm for multi-floor facility layout problems having inner structure walls and passages

This study proposes an improved genetic algorithm to derive solutions for multi-floor facility layouts that are to have inner structure walls and passages. The proposed algorithm models the multi-floor layout of facilities on gene structures. These gene structures consist of a five-segmented chromosome. Improved solutions are produced by employing genetic operations known as selection, crossover, inversion, mutation, and refinement of these genes for successive generations. All relationships between the facilities, passages, and lifts are represented as an adjacency graph. The shortest path and distance between two facilities is calculated using Dijkstra's algorithm of the graph theory. Comparative testing shows that the proposed algorithm performs better than other existing algorithm for the multi-floor facility layout design. Finally, the proposed algorithm is applied to the multi-deck compartment layout problem of the ship with the computational result compared with the multi-deck compartment layout of the actual ship.     

An improved genetic algorithm for facility layout problems having inner structure walls and passages

This study proposes an improved genetic algorithm (GA) to derive solutions for facility layouts that are to have inner walls and passages. The proposed algorithm models the layout of facilities on gene structures. These gene structures consist of a four-segmented chromosome. Improved solutions are produced by employing genetic operations known as selection, crossover, inversion, mutation, and refinement of these genes for successive generations. All relationships between the facilities and passages are represented as an adjacency graph. The shortest path and distance between two facilities is calculated using Dijkstra's algorithm of graph theory. Comparative testing shows that the proposed algorithm performs better than other existing algorithms for the optimal facility layout design. Finally, the proposed algorithm is applied to ship compartment layout problems with the computational results compared with an actual ship compartment layout.Scope and purposeFacility layout problems (FLPs) concerning space layout optimization have been investigated in depth by researchers in many fields, such as industrial engineering, management science, and architecture, and various algorithms have been proposed to solve FLPs. However, these algorithms for the FLP cannot consider inner structure walls and passages within the block plan (or available area). They are also limited to a rectangular boundary shape of the block plan. Therefore, these algorithms could not be directly applied to problems having the curved boundary shape such as ship compartment layout, and an innovative algorithm which can treat such problems is needed. In this study, an improved genetic algorithm (GA) is proposed for solving problems having the inner structure walls and passages within an available area of a curved boundary. A comparative test of the proposed algorithm was performed to evaluate its efficiency. Finally, the proposed algorithm is applied to ship compartment layout problems with the computational results compared with an actual ship compartment layout. From the comparative test and the preliminary applications made to the ship's compartment layout, we demonstrate that the proposed algorithm has the ability to solve the FLPs having the inner structure walls and passages within the available area of the curved boundary.     

Mathematical formulation and a new metaheuristic for the constrained double-floor corridor allocation problem

A layout plan for a manufacturing system that is designed without any facility constraints will most likely be infeasible when confronted with reality. Additionally, considering that land available for building industrial plants is limited and its cost is high, it is necessary to investigate the layout planning of two and multi-floor facilities. To address these shortages in the scientific literature, we focus on the double-floor corridor allocation problem (DFCAP) which covers a wide range of complex facility constraints, such as fixed floor constraints, fixed row constraints, fixed positioning constraints, mutual floor constraints, mutual row constraints, sequencing constraints and adjacency constraints. For the model mentioned above, we term it as a constrained DFCAP (cDFCAP). A mixed-integer linear programming model is formulated for the cDFCAP. In order to solve larger realistic problems, a constrained metaheuristic with the memetic algorithm framework customised for solving the cDFCAP is introduced in this work. In our algorithm, four problem-specific heuristic rules to construct a set of initial solutions are developed. In addition, an ideal parameter combination for our constrained memetic algorithm is determined through a Taguchi experimental design. Finally, the results of a set of cDFCAP instances with different sizes (n = 10∼80) report that our provided approach is effective for the considered problem.     

考虑搬运车辆空载的多行设备布局设计

对于多行设备布局问题,通过对搬运车辆运行情况的分析,建立的模型中以搬运设备的重载运行和空载运行的费用之和最小作为目标函数,设计了相应的遗传算法来求解。通过一个实例进行了模拟计算,进一步与原有模型的仿真结果进行了比较。比较结果说明了利用该模型得到的设备布置方案要优于采用原有模型得到的布置方案。     

用CLP技术解决动画自动生成中的布局规划问题*

以本实验室研制的一个多重论域的约束逻辑程序设计系统BPUCLP为基础,提出用约束逻辑程序(Constraint Logic Programming,CLP)解决布局规划问题。该方法用几何模型表示对象,用算术约束描述对象间的位置关系,并通过BPUCLP的约束求解机制为各个位置变量取值。该方法实现了二维人物初始布局规划和三维卧室家具布局规划。实验证明该方法是有效的。     

An assignment model for dynamic load planning of intermodal trains

Intermodal terminals are important facilities in the container transport network, providing an exchange of containers between road and rail transport. Numerous factors can affect throughput in such highly integrated systems. These include numbers and types of equipment, physical layout, storage capacity and operating strategies. This study aims to improve operating strategies by developing an analytical tool to assist in load planning of container trains. The problem investigated can be described as a dynamic assignment problem with many uncertain parameters. Numerical investigations focus on tuning the proposed model to deal with the uncertainties.