Structural Optimization of Automotive Body Components Based on Parametric Solid Modeling

Parametric modeling was used to build several models of an automotive front structure concept that utilizes carbon fiber composite materials and the corresponding molding processes. An ultra-lightweight aluminum body front structure was redesigned to include an all-composite front structure. Two alternative concepts were studied which represent the structure as a bonded assembly of shells. Closed sections result from two pieces – an inner and outer. Parametric modeling was found to be a useful tool for building and modifying models to use in optimization concept studies. Such models can be built quickly and both the sketch dimensions and location dimensions are particularly useful for making the adjustments necessary to fit the various body pieces together. The parametric models then must be joined together as one geometric solid model in order to obtain a surface mesh. Structural optimization input data can then be seamlessly and quickly created from the parametric-model-based finite element model to begin the tradeoff studies. This integrated process in which parametric modeling was coupled with structural optimization was used to carry out design studies on the lightweight body front structure. Several carbon fiber material combinations were studied to determine mass reduction potential of certain types of carbon fiber products considered to be lower cost than typical carbon fiber materials used in the past. Structural optimization was used to compare several composite constructions for the design of the bonded front structure. Eight cases were studied using various materials and composite lay-ups. Mass savings estimates from 45–64% over steel were obtained. The most reasonable design consisted of a combination of relatively low cost chopped carbon fiber and woven carbon fiber and using a 20 mm balsa core in the top of the shock tower area. This design had a maximum thickness of 7 mm and a mass reduction over steel of approximately 62%.     

The Design of the Zinc Modelling Language

Zinc is a new modelling language developed as part of the G12 project. It has four important characteristics. First, Zinc allows specification of models using a natural mathematical-like notation. To do so it supports overloaded functions and predicates and automatic coercion and provides arithmetic, finite domain and set constraints. Second, while Zinc is a relatively simple and small language, it can be readily extended to different application areas by means of powerful language constructs such as user-defined predicates and functions and constrained types. Third, Zinc provides sophisticated type and instantiation checking which allows early detection of errors in models. Finally, perhaps the main novelty in Zinc is that it is designed to support a modelling methodology in which the same conceptual model can be automatically mapped into different design models, thus allowing modellers to easily “plug and play” with different solving techniques and so choose the most appropriate for that problem. We describe in detail the various language features of Zinc and the many trade-offs we faced in its design.     

Modelling of a dual circuit induced draft cooling water system for control and optimisation purposes

The successful operation of any petrochemical plant is dependent on the use of several utilities which may include electricity, steam, compressed air, cooling media, refrigeration media, nitrogen, condensate and fuel gas. These utilities form a significant portion of the fixed cost associated with running a plant. Utility optimisation has not received much attention until recently, driven by rising energy costs, stricter environmental policies, more competitive markets, and the threat of climate change. The generation, preparation, and transportation of utilities require energy and therefore should be optimised to reduce losses and improve operating efficiency. One example of such a utility is a cooling water system. This paper describes the modelling of a dual circuit induced draft cooling water system for control and optimisation purposes. The derived model is verified with plant data indicating promising results. The model is represented in a steady-state algebraic form as well as a dynamic state-space form. This provides a convenient basis for simulation studies and controller/optimiser design.     

碳纤维复合材料的超声反射波频域定征分析

对碳纤维复合材料的孔隙率进行超声测试法研究,发现材料前后表面超声回波均值频率偏移量与材料内部孔隙率,与超声信号衰减之间存在着特定关系.提出前后表面回波均值频率偏移特性为基础的超声无损表征方法,通过最小二乘法算法对材料内部孔隙率和超声衰减进行了定量分析,实验结果证明了该方法的实用性.     

Modelling and simulation of a copper electrolysis cell group

The energy consumption of the copper electrolysis process is relatively high. Electrical disturbances – like contact failures and short circuits – even increase the energy consumption and also reduce the quality of copper produced. To better understand and improve the process, a computationally feasible and reliable model of copper electrolysis cell group is of great importance. In this paper a multiphysical FEM model of copper electrolysis cell group is presented. A number of simplifications are proposed to make the model computationally feasible.     

CAD/CAM研究概况之一——CYBER910工作站及ATS软件

本文主要介绍西北轻工业学院CAD/CAM技术开发中心使用美国CDC公司的CYBER 910工作站及其ICEM软件和新加坡ATS电脑私人有限公司的CAD/CAE软件进行的开发研究工作。     

Design and Evaluation of a Carbon Nanotube-Based Programmable Architecture

In the hunt to find a replacement to CMOS, material scientists are developing a wide range of nanomaterials and nanomaterial-based devices that offer significant performance improvements. One example is the Carbon Nanotube Field Effect Transistor, or CNFET, which replaces the traditional silicon channel with an array of semiconducting carbon nanotubes (CNTs). Given the increased variation and defects of nanometer-scale fabrication, and the regular nature of bottom-up self-assembly, field programmable devices are a promising initial application for such technologies. In this paper, we detail the design and evaluation of a novel nanomaterial-based architecture called FPCNA (Field Programmable Carbon Nanotube Array). New nanomaterial-based circuit building blocks are developed and characterized, including a lookup table created entirely from continuous CNT ribbons. To accurately determine the performance of these building blocks, we create variation-aware physical design tools with statistical timing analysis that can handle both Gaussian and non-Gaussian random variables. When the FPCNA architecture is evaluated using this CAD flow, we see a 2.75× performance improvement over an equivalent CMOS FPGA at a 95% yield. In addition, FPCNA offers a 5.07× footprint reduction compared to the baseline FPGA.     

具有离散采样和调制特性的非线性系统建模

本文用逻辑开关函数法,建立了具有离散采样和调制特性的变流器非线性系统理论模型.此模型适用于整流器、逆变器、变频器等含晶闸管元件的非线性系统动态模拟、谐波计算和稳定性研究.本文列举了此模型在变流器系统动态和谐波分析方面的应用结果.     

Modelling of Optimal Expansion of a Fuzzy Competence Set

A Competence Set, which is a Habitual Domain (HD), is a collection of knowledge and skills. We use these knowledge and skills to solve problems. Based on the concept of fuzzy set theory, this study proposes a method to find an optimal process to expand one's competence set. This process presents an expansion order and by a directed graph, the optimal path of expansion at each stage can be found by a proposed model. This model is a minimization form constrained by max-product fuzzy relation inequalities. With this model, not only the compound skills can be considered, but also the levels of the acquired skills to solve a problem can be described. Theoretical support is accompanied by an illustrative example.     

Modelling and control of a Fuel Cell System and Storage Elements in transport applications

This paper presents in a first step, a modelling approach to control auxiliaries of a PEM Fuel Cell and the design of control laws. Anode and Cathode compartments are considered to derive the voltage behaviour of the Fuel Cell and to control air and hydrogen flow rate as well as pressure. In a second step, the structure specification of an electrical power train with Fuel Cell for high power transport applications is presented. Two choppers are designed and controlled to deliver the power demand from the Fuel Cell itself and Storage Elements added. This work shows that we can characterise and adjust the system control on an actual operating cycle.     

Modelling of piezoelectric transducers applied to piezoelectric motors: a comparative study and new perspective

There has been a great deal of interest devoted to modelling and simulation of electromechanical transducers, and in particular to piezoelectric transducers, during the last decades. Modelling of the electro-mechanical phenomena is a complex matter: transducers comprise laminated structures of varying thickness, consideration of piezoelectric forcing, non-uniform electric field inside the ceramic … Several approaches for modelling the laminate structure have been reported, i.e. classical lamination theory, first order and higher order shear deformation theories. Likewise, the constitutive equations of the piezoelectric media have been included in FEA approaches. In addition, non-uniform electric fields, both linear and quadratic, were analysed. The particular case of travelling wave ultrasonic motors is addressed. This paper reports the comparative results of modelling all these plus additional transducer effects on the accuracy and presents the application to the classical electro-mechanical modelling of the stator of piezoelectric motors. Modelling results are compared with experimental data.     

有限元计算后期处理控件的研究与设计

在有限元计算的后期处理中,矢量场的可视化是相当重要的工作。该文利用ActiveX控件技术,提出了三维矢量场控件的设计方案,为工程计算人员提供了方便。     

Modelling and parameter estimation of a ship boiler

This paper deals with the identification and parameter estimation part of an adaptive control system for a ship boiler. The adaptive control system should be of such a form that it could be implemented on a minicomputer and easily adjusted to other ship boilers with similar characteristics. A nonlinear model of the process, suitable for parameter estimation purposes will be presented and the Extended Kalman filter approach to the estimation problem will be studied. Results based on plant measurements and simulations will be given.     

FC Target的设计与实现

介绍了基于FCP协议的FC target的实现方案.阐述了initiator与target端的体系结构,描述了FCPI/O报文的处理方式.实验结果表明,FCP能够使光纤网络性能得到充分发挥,系统的总体I/O性能明显优于基于iSCSI协议的IP-SAN.     

Modelling of Non‐Periodic Aggregates Having a Pile Structure

This paper presents a procedure for modelling aggregates such as piles that consist of arbitrary components. The method generates an aggregate of components that need to be accumulated, and an aggregate shape represents the surface of the target aggregate. The number of components and their positions and orientations are controlled by five parameters. The components, the aggregate shape and the parameters are the inputs for the method which involves placement and refinement steps. In the placement step, the orientation and initial position of a component are determined by a non‐periodic placement such that each component overlaps its neighbours. In the refinement step, to construct a pile structure, the position of each component is adjusted by reducing the overlap.     

Body Structure Design,Simulation and Parameter Optimization of a Crawler Type Mobile Flat Bedplate Frame Composite Car

The report mainly studied the crawler frame motion platform to reduce weight and increase the intensity. Report described the structural design process which using CAD/CAE technology for solid modeling, simulation analysis, parameter optimization. And it also explained the outstanding advantages of CAD/CAE technology in mechanical design as well as simulation analysis.     

工程布局CAD系统设计与实现

针对工程布局设计的复杂性,提出了开放式的工程布局设计CAD系统的结构框架,讨论了实现该系统的关键方法,包括自动化设计进程建模、基于功能特征的待布物和布局空间几何近似建模、布局知识和布局约束的表达、布局方法应用.基于该系统框架,实现了计算机辅助工程布局设计原型系统,并以车辆动力舱布局设计为背景,对原型系统的有效性进行了验证.