A model for assessing the layout structural complexity of manufacturing systems

The layout of a manufacturing facility/system not only shapes its material flow pattern and influence transportation and operation cost, but also affects logistics and parts/machine assignment decisions. The layout of manufacturing systems determines its structural complexity by virtue of its design configuration characteristics. This paper introduces a new model and indices for assessing the structural complexity of manufacturing systems layout in the physical domain. Six complexity indices, based on the physical structural characteristics of the layout, have been introduced and formulated. They are layout density, path, cycle, decision points, redundancy distribution and magnitude indices. An overall Layout Complexity Index (LCI) which combines all indices is developed using a novel method based on radar plots which is insensitive to the order of plotting the individual indices. The use of the developed LCI is demonstrated using six typical types of manufacturing systems layouts and relevant guidelines are presented. The developed model and complexity indices help design system layouts for least complexity and compare layout alternatives that meet the specifications, at early design stages. It supports making trade-off decisions regarding manufacturing systems flexibility and complexity and their associated costs.     

Multiobjective layout optimization of robotic cellular manufacturing systems

This paper proposes a multiobjective layout optimization method for the conceptual design of robot cellular manufacturing systems. Robot cellular manufacturing systems utilize one or more flexible robots which can carry out a large number of operations, and can conduct flexible assemble processes. The layout design stage of such manufacturing systems is especially important since fundamental performances of the manufacturing system under consideration are determined at this stage. In this paper, the design criteria for robot cellular manufacturing system layout designs are clarified, and objective functions are formulated. Next, layout design candidates are represented using a sequence-pair scheme to avoid interference between assembly system components, and the use of dummy components is proposed to represent layout areas where components are sparse. A multiobjective genetic algorithm is then used to obtain Pareto optimal solutions for the layout optimization problems. Finally, several numerical examples are provided to illustrate the effectiveness and usefulness of the proposed method.     

制造系统中的单向环型设备布局设计

提出一种优化建模与虚拟现实技术相结合的求解策略，较好地解决了制造系统中的单向环型设备布局问题．研究该问题的固有特性，提出三条定理，构建了一个启发式算法，并实现了一个沉浸式虚拟布局设计的例子．     

Loop layout design problem in flexible manufacturing systems using genetic algorithms

A common layout for flexible manufacturing systems is a loop network with machines arranged in a cycle and materials transported in only one direction around the cycle. Traffic congestion is usually used as the measure for evaluating a loop layout, which is defined as the number of times a part traverses the loop before its processing is completed. This paper investigates the problem of designing a loop layout system with genetic algorithms. The essence of the problem is how to determine the order of machines around the loop subject to a set of part-route constraints so as to optimize some measures. A hybrid approach of genetic algorithms and neighborhood search is developed for solving the problem. The proposed method is tested on hypothetical problems. Computational results demonstrate that genetic algorithms can be a promising approach for loop layout design in flexible manufacturing systems. Two typical measures, the minsum and minmax congestion measures, are examined and computational experiments show that the minsum approach outperforms the minmax approach.     

Solving a multi-floor layout design model of a dynamic cellular manufacturing system by an efficient genetic algorithm

This paper presents a mixed-integer programming model for a multi-floor layout design of cellular manufacturing systems (CMSs) in a dynamic environment. A novel aspect of this model is to concurrently determine the cell formation (CF) and group layout (GL) as the interrelated decisions involved in the design of a CMS in order to achieve an optimal (or near-optimal) design solution for a multi-floor factory in a multi-period planning horizon. Other design aspects are to design a multi-floor layout to form cells in different floors, a multi-rows layout of equal area facilities in each cell, flexible reconfigurations of cells during successive periods, distance-based material handling cost, and machine depot keeping idle machines. This model incorporates with an extensive coverage of important manufacturing features used in the design of CMSs. The objective is to minimize the total costs of intra-cell, inter-cell, and inter-floor material handling, purchasing machines, machine processing, machine overhead, and machine relocation. Two numerical examples are solved by the CPLEX software to verify the performance of the presented model and illustrate the model features. Since this model belongs to NP-hard class, an efficient genetic algorithm (GA) with a matrix-based chromosome structure is proposed to derive near-optimal solutions. To verify its computational efficiency in comparison to the CPLEX software, several test problems with different sizes and settings are implemented. The efficiency of the proposed GA in terms of the objective function value and computational time is proved by the obtained results.     

Topology Optimization in Aircraft and Aerospace Structures Design

Topology optimization has become an effective tool for least-weight and performance design, especially in aeronautics and aerospace engineering. The purpose of this paper is to survey recent advances of topology optimization techniques applied in aircraft and aerospace structures design. This paper firstly reviews several existing applications: (1) standard material layout design for airframe structures, (2) layout design of stiffener ribs for aircraft panels, (3) multi-component layout design for aerospace structural systems, (4) multi-fasteners design for assembled aircraft structures. Secondly, potential applications of topology optimization in dynamic responses design, shape preserving design, smart structures design, structural features design and additive manufacturing are introduced to provide a forward-looking perspective.     

Integrated design of workcells and unidirectional flowpath layout

In manufacturing cells layout design with a unidirectional flow system, the accurate distance between two workcells can be uncovered with both the determination of IO port locations after the layout design of the cell with its orientation and the unidirectional flowpath layout design. This paper presents the method to obtain a global solution for manufacturing workcells and unidirectional flowpath layout design (ICFLD) with consideration of IO ports of workcells. The flow distance between two workcells is calculated from output port of one workcell to input port of the other workcell through the unidirectional flowpath layout. A zero-one integer programming model is developed for the ICFLD problem. And a heuristic algorithm for the ICFLD problem is developed by decomposing the ICFLD problem into two subproblems and iteratively and alternately solving the decomposed subproblems. Computational experiments are performed and its results are analyzed.     

An extraction-based verification methodology for MEMS

Micromachining techniques are being increasingly used to develop miniaturized sensor and actuator systems. These system designs tend to be captured as layout, requiring extraction of the equivalent microelectromechanical circuit as a necessary step for design verification. This paper presents an extraction methodology to (re-)construct a circuit schematic representation from the layout, enabling the designer to use microelectromechanical circuit simulators to verify the functional behavior of the layout. This methodology uses a canonical representation of the given layout on which feature-based and graph-based recognition algorithms are applied to generate the equivalent extracted schematic. Extraction can be performed to either the atomic level or the functional level representation of the reconstructed circuit. The choice of level in hierarchy is governed by the trade off between simulation time and simulation accuracy of the extracted circuit. The combination of the MEMS layout extraction and lumped-parameter circuit simulation provides MEMS designers with VLSI-like tools enabling faster design cycles, and improved design productivity     

Intelligent approach to a CAD system for the layout design of a ship engine room

The current layout design of a ship engine room not only depends on a skilled designer but also has many design constraints and regulations to be considered. At preliminary design stage CAD systems need to be intelligent in the sense that they must be able to use knowledge to achieve the designer’s goal. In this paper, we present an approach to implement a practical knowledge-based system for the machinery layout design of a ship engine room. The knowledge-base is implemented and verified in the actual CAD environment of a ship engine room, named MADES (Machinery ArrangementDesign Expert System), which we develop in this study. Design knowledge is represented byobject-oriented concept, and nonmonotonic reasoning enables the values of closely related objects to be consistent. The approaches presented in this paper provide a practical example of a knowledge-based system for complex design problems, and can also provide guidance on implementing an integrateddesign expert system that extends the capability of existing CAD systems.     

A granularity model for balancing the structural complexity of manufacturing systems equipment and layout

The structural complexity of a manufacturing system results primarily from the complexity of its equipment and their layout. The balance between both complexity sources can be achieved by searching for the best system granularity level, which yields a manufacturing system with the least overall structural complexity. A new system granularity complexity index is developed to sum up and normalize the complexity resulting from the system layout complexity and the equipment structural complexity. A previously developed layout complexity index together with a code-based structural complexity assessment are used to determine the structural complexity of standalone pieces of equipment and to arrive at a balance between the two sources of complexity. Cladistics analysis is used to hierarchically cluster required pieces of equipment and bundle them into more integrated equipment and machines and demonstrate the possible different system granularity levels. The new developed model is a useful tool to create specific system configuration and layout alternatives based on system components adjacency, and then select the system design with the least overall structural complexity among those alternatives. The results of the presented case study clearly demonstrated this trade-off where decomposing manufacturing systems into a highly granular configuration with standalone machines maximizes system layout complexity and minimizes equipment complexity, while at a low level of granularity pieces of equipment are bundled into complex integrated machines, lines or cells but with a very simple system layout.     

面向结构化布局设计的产品布局多色模型

为实现产品原理方案向结构化布局映射,提出产品布局元层次关系网及产品布局多色模型.首先在布局模块及其属性关系网的基础上构建布局元层次关系网;然后应用多色集合的个人颜色、统一颜色,给出产品布局元层次关系网的数学描述,形成产品布局多色模型,并提出推理算法;再利用个人颜色、统一颜色之间的围道布尔矩阵推理原理,进行产品结构布局设计过程中功能—运动分配—布局模块之间映射过程的形式化描述.应用该模型进行结构化布局设计,可有效地支持产品结构布局设计的公理化;最后在Pro/E平台中利用VC.net 2003工具进行二次开发,并以数控机床结构布局设计为例验证了文中模型和设计方法的可行性和有效性.     

浅谈杂志目录页的版式设计

一直以来,我国的书籍设计只注重封面设计而忽视目录页的编排设计,在目录页的编排设计中,仅局限于它的检索功能,而忽视审美功能和设计内涵。其实,目录页版式设计非常重要,读者会通过浏览目录页来了解这本书的内容概要,感受杂志的特色和风格。因此,目录页设计应该从单纯的提供信息转化为调动读者的视觉感受上来。文章尝试从目录页的发展历史中,归纳出杂志目录页的版式设计规律,重新审视目录页版式设计对于平面设计的研究价值。     

Application of a cascade BAM neural expert system to conceptual design for facility layout

The major contribution of this novel application is the pilot development and feasibility study for a bank of cascade BAM (Bidirectional Associative Memories) neural networks. This improved BAM structure functions as an expert system for conceptual facility layout or for preliminary construction layout design. This application, rather than being a better analytical algorithm or a better production expert system, builds a neural expert system with the capability of incrementally learning layout design examples for a given set of constraints. The cascade BAM incremental learning methodology, which distinguishes this system from the more frequently used Backpropagation Network (BPN) learning system, creates effective multibidirectional generalization behavior from qualitative, goal-driven layout design experience. The initial tests of learnability are presented by its applicability to conceptual layout design problems, and their solutions are assessed and compared with the learning ability of a standard BAM. Issues deserving further investigation are addressed as well.     

平面设计中的版式设计

当今经济高速发展,无论是超市里琳琅满目的商品,还是街道上无处不在的广告栏,无一例外的都包含着版式设计的要素。版式设计随着社会的发展在不同的时期受到各种文化、艺术流派风格的影响,形成了一些设计风格。20世纪80年代以来,电脑的广泛应用巨大的改变了平面设计的现状。随着时代的发展,平面设计中的版式设计发挥着越来越重要的作用,也是设计师需要进一步研究的课题。     

Optimal design of plant lighting system by genetic algorithms

A genetic algorithm technique is developed for the optimal design of a supplemental lighting system for greenhouse crop production. The approach uses the evolutionary parallel search capabilities of genetic algorithms to design the pattern layout of the lamps (luminaires), their mounting heights and their wattages. The total number and the exact positions of luminaires are not predefined (even though possible positions lay on a fixed grid layout), thus the genetic algorithm system has a large degree of freedom in the designing process. The possibilities of mounting heights and luminaire wattages are limited to four different values for each luminaire in this study. A fitness function for the genetic algorithm was developed, taking into account light uniformity, light intensity capability, shading effects of the design, as well as operational and investment costs. The systems designed by the genetic algorithm show improved values of light uniformity and substantial savings without any effect on the light capacity capabilities of the system. Innovative automatically designed systems compare favorably with typical and expert-designed lighting systems.