An optimal layout of container yards

This study presents a method for designing the layout of container yards where transfer cranes and yard trucks are used for stacking containers in the yard and delivering them between the yard and the quay. A method to determine the layout type, the outline of the yard, and the numbers of vertical and horizontal aisles is suggested. For estimating the effects of the design variables on operational cost terms, formulas for estimating the number of relocations by yard cranes and the expected travel distance of trucks are derived. Numerical examples are provided to illustrate the design procedure. It was also shown that the layout in which blocks are laid out parallel to the side with the gate or the quay outperforms that in which blocks are laid out perpendicular to the side with the gate or the quay.     

Fuzzy computer-aided design of process manufacturing facilities

Preliminary design of process manufacturing facilities involves, among other things, the synthesis of detailed layout designs. In current practice, this spatial design process is very labor-intensive and expensive. This paper describes a prototype CAD system which models design decision-making, providing a computable framework for automation. The CAD system performs auto-elicitation of an expert's judgment in the form of fuzzy sets using interactive computer graphics. These fuzzy sets are then used in a heuristic search process employing multi-objective, non-linear optimization. Designs synthesized by this fuzzy CAD system are comparable to those generated by hand, and in some cases exceed a practitioner's design in quality. The CAD system, as presently constructed, provides multiple solutions. Conclusions and recommendations regarding processing speed and unrepresented heuristic content are made.     

Allowing for weight considerations in container loading

Only very few of the existing container loading algorithms include in their logic any references to the weight or the load bearing abilities of the items to be stowed. The paper aims to make a contribution to overcoming this shortcoming. It shows how a procedure which has already been evaluated in some detail in the literature can be adapted in a fairly straightforward manner to deal with fragility considerations. The approach suggested is based on opportunity cost notions. It is demonstrated that the results obtained can be vastly superior to a procedure which considers load bearing ability merely in terms of a constraint on the packing options available at each stage. Additional refinements of the basic approach and questions related to its practical implementation are also discussed, as are possible extensions to enable `soft' positioning rules to be incorporated. Received: 6 February 1997 / Accepted: 25 June 1997     

VLSI floorplan repair using dynamic white-space management,constraint graphs,and linear programming

In VLSI layout, floorplanning refers to the task of placing macrocells on a chip without overlap while minimizing design objectives such as timing, congestion, and wire length. Experienced VLSI designers have traditionally been able to produce more efficient floorplans than automated methods. However, with the increasing complexity of modern circuits, manual design flows have become infeasible. An efficient top-down strategy for overlap removal which repairs overlaps in floorplans produced by placement algorithms or rough floorplanning methodologies is presented in this article. The algorithmic framework proposed incorporates a novel geometric shifting technique coupled with topological constraint graphs and linear programming within a top-down flow. The effectiveness of this framework is quantified across a broad range of floorplans produced by multiple tools. The method succeeds in producing valid placements in almost all cases; moreover, compared with leading methods, it requires only one-fifth of the run-time and produces placements with 4–13% less wire length and up to 43% less cell movement.     

Stability aspects of pallet loading

Summary The algorithm-orientated literature on packing problems has concentrated on methods for achieving an efficient utilisation of the transport or storage medium concerned. Many problems arising in practice, however, also involve other objectives in addition to that of minimising unused space. The stability of the load is a prime example. The paper considers the stability objective in the context of pallet loading and examines approaches for generating stable stacking patterns that are also optimal from the viewpoint of space utilisation. A statistical performance analysis of the methods described is presented and potentially fruitful directions for further research are discussed.     

仿生学与包装设计

通过许多实例,从生物自我包装的原理和功能、包装造型设计这两个方面,论述了仿生学原理在商品包装设计中的应用现状及前景。     

Design of unidirectional cyclic layouts

This work is concerned with the unidirectional cyclic layout problem, which is known to be NP-complete. This type of problem arises, for example, in the determination of workstation locations around a closed loop conveyor system, in the allocation of cutting tools on the sites around a turret, in the positioning of stations around a unidirectional single loop AGV path. Although it can be formulated as a Quadratic Assignment Problem, in general there are two special cases satisfying additional assumptions. In the Balanced Unidirectional Cyclic Layout problem, the material flow is conserved at every workstation. In the Equidistant Unidirectional Cyclic Layout Problem, distances between circular candidate locations are all equal. It is known that both problems are equivalent, which makes any valid formulation of the balanced flow problem also valid for the equidistant problem and vice versa. We first analyse and show new features of the existing formulations. Then we discuss and propose new heuristics using ideas originally introduced for two well-known combinatorial optimization problems: the Asymmetric Travelling Salesman Problem and the Linear Ordering Problem. Based on the computational tests we can say they are both accurate and efficient.     

Evaluation of heuristics for a class-constrained lot-to-order matching problem in semiconductor manufacturing

While semiconductors are being used in an increasing number of products, semiconductor manufacturers continually look for ways to make their processes more efficient. This paper will focus on an issue in the manufacturing process called the class-constrained lot-to-order matching problem (CLOMP), where individual lots of microprocessors are matched to customer orders, while seeking to optimize multiple objectives. Due to its complexity, the problem is decomposed into two stages—the first identifies which customer orders to fill while the second assigns specific lots to the chosen orders. We design an experiment with four first-stage sorting rules, four second-stage heuristics and two production cases. Based on our simulation results, this paper will recommend the first-stage sorting rule and second-stage heuristic which attain the best results with regards to our measures of effectiveness.     

An application of an expert system in layout compaction of VLSI design

Abstract

Recent research in knowledge‐based expert systems of VLSI design tools has concentrated on placement, routing, and cell generation. This paper presents an alternative application for artificial intelligence (AI) techniques on compaction design for a VLSI mask layout‐expert compactor. In order to overcome the shortcomings of iterative search through a large problem space within a working memory, and therefore, to speed‐up the runtime of compaction, a set of rule‐based region query operations and knowledge‐based techniques for the plane sweep method are proposed in this system. Experimental results have explored the possibility of using expert system technology (EST) to automate the compaction process by “reasoning” out the layout design and applying sophisticated expert rules to its knowledge base.     

Linear programming and Lagrangian relaxation heuristics for designing a material flow network on a block layout

This paper focuses on the problem of designing a material flow network for a given block layout. For an efficient design of a network, we simultaneously consider locations of input and output points, flow paths, and the smoothness of material flow paths. A mixed integer programming formulation is given for the problem with the objective of minimising the sum of transportation cost, cost related to flow paths, and penalty cost for non-smooth flows, i.e., flows with many turns. We suggest two heuristic algorithms based on the linear programming relaxation and the Lagrangian relaxation techniques. To evaluate performance of the suggested algorithms, a series of computational experiments is performed on well-known problem instances as well as randomly generated test problems. Results show that the suggested algorithms give good solutions in a reasonable amount of computation time.     

出奇才能制胜--谈包装设计的个性展示

现代市场经济高度繁荣,商品经济的竞争也非常激烈,良好的产品包装在此起着前所未有的重要作用。要使包装得到消费者的认可,包装设计的个性化体现则是其中的关键。     

产品操作界面元素布局多目标优化设计

目的针对产品设计中操作界面布局设计时存在的随意性、不确定性大等问题,使用多目标优化设计的方法,寻找界面元素的最优布置,以提升界面的使用舒适性和人机交互效率。方法在分析了工效学准则和界面布局美度评价准则的基础上,确立了层次性、相关性、简洁性和舒适性四个界面布局基本原则,并依据原则构建了界面元素布局多目标优化数学模型,在此模型的基础上采用改进的遗传算法,建立基于遗传算法的界面元素布局多目标优化方法。结果给出产品操作界面布局设计的基本原则,提出一种基于遗传算法的产品操作界面元素布局的多目标优化方法及流程。结论提出的布局原则和优化方法能较好地协助设计师获得满足设计需求的布局方案,实例结果表明了理论模型的合理性与遗传算法对于界面元素布局多目标优化问题求解的有效性。     

Two new heuristic algorithms for the maximal planar layout problem

The adjacency problem is an important subproblem in facility layout planning. It is known to be NP-complete, so heuristics are required to solve large problem instances. In this paper two new heuristics for the adjacency problem are introduced which belong to a special class of constructive methods called Triangulation Expansion Heuristics. Extensive numerical experiments have been carried out in order to evaluate the proposed methods in terms of computing times and solution quality. It has been found that at least one method is clearly superior to the best methods proposed in the literature so far (Eades et al. 1982, Leung 1992).     

A simulated annealing algorithm based on a closed loop layout for facility layout design in flexible manufacturing systems

Facility layout design problems in flexible manufacturing systems (FMS) differ from traditional facility design problems and are more difficult to solve because there are more constraints that must be considered (i.e., cell shape, cell orientation, pick-up and drop-off point positions). The focus of this paper is on the closed loop type layout, which is based on a predetermined layout pattern. This layout pattern is commonly found in manufacturing settings since it requires a simplified material handling system configuration and since it facilitates a modular and expandable layout structure. The open-field type layout problem, where there is no predetermined layout pattern, may potentially have a more efficient configuration, since there are fewer restrictions. However, this problem is more difficult to solve and may result in configurations that are not desirable due to the lack of structure or modularity. The procedure developed in this paper improves the efficiency of the closed loop configuration by changing the rectangular shape of the loop to different sizes. In many cases, the resulting closed loop layout proves to be as efficient as the open field layout. A simulated annealing procedure (SA-CL) is used to search for the configuration that minimizes the total material handling costs. A comparison of the results with existing methods indicates that, based on solution quality and computational time, the SA-CL offers a favourable alternative for efficient layout design.     

科学与艺术地打造包装

提出了科学与艺术的完美结合才能构造一件优秀的包装。并对实现这一目的,在包装设计中应如何进行和成功地把握进行了探讨。     

Solution of facility layout problems with pickup/drop-off locations using random search techniques

Due to non-polynomial hardness, the facility layout problem (FLP) becomes more critical when pickup/drop-off (P/D) locations are considered in the design of an open field layout under a manufacturing environment. This paper proposes an indigenous model of the facility layout problem based on random search techniques and its solution methodology using a genetic algorithm (GA), simulated annealing (SA) and a hybrid algorithm (HA). The paper illustrates the performance of different random search operating parameters in solving the facility layout problem considering P/D locations along the periphery of rectangular machine blocks. The preliminary experiments were carried out on three facility layout test problems having six, eight and ten machines in order to fix the different operating parameters such as crossover operator, crossover rate, initial temperature, temperature reduction factor, number of generations, population size, etc. The results of extensive preliminary experimentation were utilized to solve facility layout problems having 12 and 18 machines and, finally, were compared with the existing procedures in the literature. The experimental tables and related analysis performed via the solution methods by applying GA, SA and HA revealed that random-search-based modeling of FLP considering P/D and its solution as suggested in this paper is worth pursuing.     

系统化理念中的包装设计

缺乏整合性的无序包装设计状态,既不利于包装科技的发展,也影响了包装业在经济建设中的价值定位及可持续发展战略实施.文中在对包装历史与现实思考的基础上,提出了包装的系统化设计理念,以期推动当代包装设计的理性发展及设计实践的进步.