温差发电的热力过程研究及材料的塞贝克系数测定

建立了半导体温差发电器件的基本模型；从稳态的热传导方程出发，对发电器件进行了热力学分析，推导出P型和N型半导体内部的温度分布函数及输出功率和发电效率的表达式；测定了一种Bi-Te-Sb-Se半导体热电材料在低温下的塞贝克系数随温度的变化关系，绘制了曲线并进行数值拟合；结果表明，该种半导体热电材料在低温下性能不佳，需改进配方或生产工艺方可使用。     

Support tool for material and process combinations during early design

The aim of this research is to develop an Expert System (ES) that is linked into a 3D design package, which will provide comparison data for various material and manufacturing process combinations to produce a design. The early design stage is the optimum time to ensure that the material and manufacturing process chosen will realize a design's requirements.

This paper focuses on the steps within the process to create the Expert System and provides an example of its use. The CAD package chosen is AutoCAD 2004. A recognition module has been developed to recognize a 3D model and to segregate the model into that of the quadratic and polyhedron primitives within a database. A generic material and manufacturing database has been designed. This has established a basic platform from which the different material and manufacturing processes can be compared. As each manufacturing process has process-specific rules, it is necessary to examine the 3D model for the suitability of the processing method chosen within the ES.

This ES aims to increase the knowledge available to the designer to aid in the decision-making process, through the comparison reports generated and the web link and specific documentation facility within the software package.     

Architectural layout design optimization

This article presents an optimization model of the quantifiable aspects of architectural floorplan layout design, and a companion article presents a method for integrating mathematical optimization and subjective decision making during conceptual design. The model presented here offers a new approach to floorplan layout optimization that takes advantage of the efficiency of gradient-based algorithms, where appropriate, and uses evolutionary algorithms to make discrete decisions and do global search. Automated optimization results are comparable to other methods in this research area, and the new formulation makes it possible to integrate the power of human decision-making into the process.     

Design Computing Unit: University of Sydney

Conclusion Design research has a long history dating back to Vitruvius. However, it has only been in the last three decades that a small number of coherent research streams has developed. At the same time there has been an increasing interest by research funding bodies in funding design research. The research of the Design Computing Unit is concerned with developing an understanding of design as a process. It uses the computational paradigm as its starting point and treats design as a very complex form of intelligent human behavior. The results of this research are a better understanding of design as a process rather than design tools. The apparently unique nature of design, namely, how the act of designing changes the stated problem, means that research into design requires more than the simple importation of ideas from other areas. Design research is only now coming to grips with the need to generate its own paradigm.     

Data frame model for the engineering design process

Computers are being integrated into the technological design process, just as they are being integrated into banking practice, airline reservations, and many other activities. Until now, computers have served as tools used by designers in methods dictated by the paper-based information systems to which humanity has become accustomed. Computers perform design calculations or analyses, and produce documentation such as drawings, schedules, specifications, and tapes to control production machines. However, as more technical information is stored in computer memories, and as the communication networks between computers develop, different working methods, adapted to electronics-based rather than paper-based information systems, may develop.This paper explores briefly the process of design, and then, using some concepts published in the last few years, proposes a model of the design process that can be implemented by computer. Emphasis is placed on the ‘frame’ concept with a final reference to recent research in artificial intelligence. The paper does not attempt to give a comprehensive survey of the subject of problem solving in engineering design. Furthermore, the ideas expressed have not yet been used to create a working design program. The examples used as illustrations of various concepts are therefore only partial.     

Manufacturing process selection in engineering design. Part 1: the role of process selection

Whilst material selection methods are becoming mature, the selection of processes has been neglected — particularly after the preliminary design stages. This paper presents a view of current approaches to selection issues in engineering design with particular reference to process selection techniques. The need is highlighted for more focused selection techniques once a manufacturing task has been identified. A new methodology to aid the creation of task-based process selection procedures is outlined in Part 2 (A.M. Lovatt, H.R. Shercliff, J. Mater. Des., 19 (1998) 217–230).     

纳滤膜系统优化设计模式探讨

纳滤膜技术在水处理领域中的规模化应用正在受到广泛关注.而纳滤膜的筛选与膜系统的优化设计是应用过程中首要解决的关键问题之一.由于纳滤膜种类繁多、对溶质截留范围宽、分离机理复杂等多变因素决定了纳滤膜系统应该采用多元化的设计模式,而不是简单模拟反渗透膜系统.选择NF270芳香族聚酰胺材料纳滤膜为例,论述了不同类型的无机盐溶液在不同压力、流量、盐度、温度、pH值等条件下,浓差极化因子对商品化纳滤膜性能的影响;并与反渗透膜性能变化规律和系统设计进行对比,给出了此类纳滤膜在一定盐度进水条件下的合理化设计建议:1)设计压力与进水盐度无关;2)系统回收率与流程长度无关;3)盐的截留率只取决于系统收率.试图为纳滤膜选择及纳滤膜系统设计新模式提供理论依据,并为提出完整的纳滤膜系统设计新模式做出初步的探索.     

SIZE EFFECTS AND A MEAN-STRENGTH CRITERION FOR CERAMICS

On the basis of a large amount of research on the fracture behaviour of ceramics, a new failure criterion is advanced. It is pointed out that the rupture of structural ceramics is governed by the mean stress in a specific zone, rather than by the peak stress value. The size of the process zone was derived as a material constant, and reflects the relation between the toughness and the strength of the material. The results show that the critical maximum stress varies with the stress gradient: the steeper the stress gradient, the higher the critical peak stress. Different experiments concerning the size effect have been carried out and the reason for size effects has been explained by a mean strength theory.     

自然思维下的体验设计研究

目的 探讨用户体验与自然思维的联系,研究自然设计思维在设计过程中的必要性和影响,分析在体验设计中自然设计思维的相关要素,以及如何运用自然设计思维要素进行产品的体验设计。方法 抛开设计者主观的认知定式,基于用户和自然的相互联系,运用用户研究方法,从用户自然行为延续研究和自然心智的合理预判中获取设计思路,并结合移动医疗设计的分析和研究进行论证。结论 人类发展的过程,就是从自然中学习并总结的过程,而用户体验设计的本质,则是理解人类在自然生活中的行为,结合伦理、心理、行为等研究,以自然交流的方法,帮助产品在新场景下顺应人类的自然思维方式。通过提出在体验设计过程中应用三大自然设计思维要素,以此建立新的自然体验设计方法,为创造出更为精准、高效、易用的产品提供借鉴。     

D/A转换器建立时间对输出信号质量的影响

考虑D／A转换器建立时间的影响，建立了D／A转换器输出信号波形的新的时域模型。在此基础上，以正弦信号的发生为例进行了频谱分析。发现了建立过程的平滑作用可以明显地削弱信号的谐波分量，并存在一个最佳转换频率，使谐波失真达到最小值。该结果为D/A信号发生器的优化设计提供了参考依据。     

A simple methodology to define conical tool geometry and welding parameters in friction stir welding

The friction stir welding is a solid state welding process which has been successfully applied for industrial parts. The process development has been supported by experimental and theoretical studies related to weld outcome, material flow and tool geometry. In this study, we propose a new methodology to define the geometry of a conical tool as well as welding parameters for the friction stir welding of thin plates of a given material. This is based on a concept that the tool geometry and process parameters must satisfy four heuristics: a thermal condition and rules relevant to volume, surface and material flow. This all should tend to ensure that the matter reaches an appropriate processing temperature and remains confined to the tool zone without any loss to the surroundings. A calculation algorithm that integrates a basic thermal model, tool geometry and process kinematics is proposed. The methodology and details of tool design are further discussed in relation with the definition of a process window. Experimental investigations on Al 2017-T4 alloys by using a shouldered unthreaded conical tool are presented in support of the model. The outcome of the model and experimental studies is further substantiated by using the published results.     

Advancements in the selective inhibition sintering process development

Selective inhibition sintering (SIS) is a new layer-based rapid prototyping process that fabricates parts by joining polymer powder particles in the part's body to form a coherent solid and by preventing particles from joining at the part's boundary to form edges. This paper presents the fundamentals of the SIS process, its dedicated path generator, material selection research and the application of response surface methodology which has led to optimum performance, given various factors affecting part strength, surface quality and dimensional accuracy.     

Advancements in the selective inhibition sintering process development

Selective inhibition sintering (SIS) is a new layer-based rapid prototyping process that fabricates parts by joining polymer powder particles in the part's body to form a coherent solid and by preventing particles from joining at the part's boundary to form edges. This paper presents the fundamentals of the SIS process, its dedicated path generator, material selection research and the application of response surface methodology which has led to optimum performance, given various factors affecting part strength, surface quality and dimensional accuracy.     

Axiomatic modelling of agile production system design

The manufacturing organisations are witnessing a transformation in the manufacturing paradigm due to increasing competition. Agile manufacturing (AM) is a contemporary manufacturing paradigm which enables the organisations to survive in this competitive scenario. Design engineering is a vital technological enabler of AM. The research on axiomatic design in the field of AM is found to be feeble. In this context, this paper reports an axiomatic model of agile production system design using process variables. A hierarchical structure has been developed to model the design process of an agile production system composed of functional requirements, design parameters and process variables. In the theory of axiomatic design, process variables are created by mapping the design parameters in the process domain. This article serves as an efficient guideline for the design process to clarify the tools, methods and resources of designing agile production system of Indian electronic switches manufacturing organisation.     

Design and operation of single-loop dual-rail inter-bay material handling system

Asynchronized automated material handling systems, e.g. automated electrified monorail systems and automated guided vehicle systems, have been playing important roles in manufacturing. Reliability becomes a critical issue as manufacturing enterprises are moving toward automation. In the past, reliability tissue has not been analysed explicitly for these types of systems. In this research, a new measure was proposed to specify reliability. A mixed integer programming model was developed to design flow paths for a special class of material handling systems, i.e. single-loop dual-rail systems. The model can be used to design systems with higher reliability. The model and application procedure in design and analysis were demonstrated through two case studies.     

国外生成式产品设计研究综述

目的 设计是一项复杂的求解过程,合适的方法对开发新产品起着至关重要的作用.设计计算的进步可能促使机器从传统的辅助角色转变为设计内容的生成器.通过回顾国外1998年至今的生成式产品设计方法,指出未来发展趋势与挑战,为产品设计师及相关的技术与应用研究者提供相应的参考.方法 从生成式设计的定义出发,给出生成式设计的定义;整理归纳生成式产品设计的主要步骤及优势;通过综述的形式,将典型的生成式产品设计方法和相关研究进行整理分类;从技术因素和设计因素两个角度总结,对比分析生成式产品设计方法.结论 数据驱动的生成式产品设计将会更好地为设计师带来全新的视角.生成式产品设计的革命性影响能否实现,将取决于设计界和业界思维方式的重大变化.生成式产品设计未来研究的影响,将取决于学术发展和行业研究之间的融合.     

Facility layout optimization using simulation and genetic algorithms

Traditionally, the objective of a facility layout problem has been to minimize the material handling cost of the manufacturing system. While it is important to reduce the amount of material handling, the traditional methods do not address the actual time at which the material is transported. In today's short cycle time production environments, the timing of material movement may have a bigger impact on the productivity of the system than its cost. In this paper, a facility layout optimization technique is presented that takes into consideration the dynamic characteristics and operational constraints of the system as a whole, and is able to solve the facility layout design problem based on a system's performance measures, such as the cycle time and productivity. Each layout solution is presented in the form of a string that is suitable for analysis by a genetic algorithm technique. These solutions are then translated into simulation models by a specially designed automated simulation model generator. Genetic algorithms are used to optimize the layout for manufacturing effectiveness while simulation serves as a system performance evaluation tool. Combined with a statistical comparison technique to reduce the simulation burden, the test results demonstrate that the proposed approach overcomes the limitations of traditional layout optimization methods and is capable of finding optimal or near optimal solutions.     

Design and characterisation of a pulsed neutron interrogation facility

The Joint Research Centre recently obtained a license to operate a new experimental device intended for research in the field of nuclear safeguards. The research projects currently being planned for the new device includes mass determination of fissile materials in matrices and detection of contraband non-nuclear materials. The device incorporates a commercial pulsed neutron generator and a large graphite mantle surrounding the sample cavity. In this configuration, a relatively high thermal neutron flux with a long lifetime is achieved inside the sample cavity. By pulsing the neutron generator, a sample may be interrogated by a pure thermal neutron flux during repeated time periods. The paper reports on the design of the new device and the pulsed fast and thermal neutron source. The thermal neutron flux caused by the neutron generator and the graphite structure has been characterised by foil activation, fission chamber and (3)He proportional counter measurements.     

A new approach to estimating the main error of a primary transducerfor an electromagnetic flowmeter

The existing methods for estimating the error caused by various flow parameters for electromagnetic flowmeters are based on nonhomogeneity in the distribution of a weight vector. The author presents a new numerical flow generator, called the moving stream method, that allows for an estimate of the primary error for a flowmeter during the design stage much more precisely than classical methods. It considers the contribution to measurement error that various flow velocities make within a measurement zone. The simulated flows account for all hydrologic conditions existing in the field     

Tyvek材料在雨衣设计中的应用

目的对Tyvek材料的性能及其在雨衣设计中的应用进行实践与研究,得出雨衣产品设计开发的新思路以及新工艺。方法基于Tyvek材料特性,应用软、硬两种不同标号的材料,用材料复合、隐藏结构、减少裁片等方法进行了雨衣设计工艺实践。结论提出了Tyvek材料在雨衣设计应用中的工艺解决新思路,即质感处理与一体式剪裁。