Implementation of rapid Prototyping technology — A Hong Kong manufacturing industry's perspective

Rapid Prototyping (RP) is a technology for rapid computerised building of 3D physical parts. It can be defined as an automated and patternless process which allows solid physical parts to be made directly from computer data in a short time. RP acts as the manufacturing middle to link up the computer-aided design (CAD) process and manufacturing processes. It includes the making of prototypes for design verification and even the making of tooling for production. With the trend towards concurrent engineering and the widespread use of CAD, RP has quickly become a booming business in the past few years. This paper presents an overview of the implementation of RP technology in Hong Kong and the critical decision factors in implementing RP in the Hong Kong manufacturing industry.     

基于Matlab的地铁系统建模与仿真

为深入研究地铁,有必要对地铁牵引供电系统及车辆进行仿真研究。通过模拟城市地铁系统实际构成与电气参数,根据地铁列车运行原理,运用Matlab／Simulink工具包提出了数学与物理模型相结合的建模方法,建立了轨道交通供电系统与机车模型。仿真得出了地铁机车运行过程中随时间、机车速度及位移变化的功率、电流、电网电压等电气参量波形。仿真结果与实测曲线相一致,表明该仿真模型真实可信。     

Experimental and finite element analysis of parameters in manufacturing of metal bellows

The current article presents an investigation into predicting tool wear in hard machining D2 AISI steel using neural networks. An experimental investigation was carried out using ceramic cutting tools, composed approximately of Al2O3 (70%) and TiC (30%), on cold work tool steel D2 (AISI) heat treated to a hardness of 60 HRC. Two models were adjusted to predict tool wear for different values of cutting speed, feed and time, one of them based on statistical regression, and the other based on a multilayer perceptron neural network. Parameters of the design and the training process, for the neural network, have been optimised using the Taguchi method. Outcomes from the two models were analysed and compared. The neural network model has shown better capability to make accurate predictions of tool wear under the conditions studied.     

New program with new approach for spectral data analysis

This article presents a high-throughput computer program, called EasyDD, for batch processing, analyzing and visualizing of spectral data; particularly those related to the new generation of synchrotron detectors and X-ray powder diffraction applications. This computing tool is designed for the treatment of large volumes of data in reasonable time with affordable computational resources. A case study in which this program was used to process and analyze powder diffraction data obtained from the ESRF synchrotron on an alumina-based nickel nanoparticle catalysis system is also presented for demonstration. The development of this computing tool, with the associated protocols, is inspired by a novel approach in spectral data analysis.     

A predicted modelling of tool life of high-speed milling for SKD61 tool steel

This paper presents an abductive network for predicting tool life in high- speed milling (HSM) operations. The abductive network is composed of a number of functional nodes. These functional nodes are well organised to form an optimal network architecture by using a predicted squared error criterion. Once the cutting speed, feed per tooth, and axial depth of cut are given, tool life can be predicted based on the developed network. Experimental results have shown that the abductive network can be used to predict HSM end mill life under varying cutting conditions and the prediction error of HSM tool life is less than 10%.     

A data acquisition and control system in the MISS electronics standard for the detector on drift tubes

A structure of the data acquisition and control system (DAQC) in the MISS electronics standard for a multichannel detector on drift tubes is described. Its special feature is the use of the specialized LE-83 controller for communications with the computer and LE-83T controller-timer, which fulfills off-line all functions of storing data in its inner memory buffers in real time without an obligatory external trigger launching signal. The rewriting of stored data from the buffer into the computer memory and their transmission via the local network occur periodically in program-specified time intervals. The received data are processed on-line to control the equipment, alert, if a fault is detected, and produce physical results directly to the operator, who interacts with the system through the graphic interface with a possibility of the setup configuration. The system is built as a set of interacting processes, which can operate both on one computer or be distributed on several computers (within the frameworks of the local network).     

PID神经网络控制器的设计及仿真研究

PID神经网络(PID-NN)是一种新型的前向神经元网络,该隐含层单元分别为比例(P)、积分(I)、微分(D)单元,各层神经元个数、连接方式、连接权初值是按PID控制规律的基本原则确定的。PID神经网络控制器是将神经网络和PID控制规律融为一体,既具有常规PID控制器结构简单、参数物理意义明确之优点,同时又具有神经网络自学习、自适应的功能。本文给出了PID-NN控制器的结构形式,计算公式,从理论上证明了PID-NN的收敛性和稳定性,最后对二阶对象下的系统进行了仿真,证明了PID-NN控制器具有较好的自学习和自适应性。     

基于神经网络的多特征融合刀具磨损量识别

采用切削力信号监测钻削过程钻头的磨损量 ,分别从时域、频域提取了切削力信号的均值、方差、峭度系数和特定频段能量作为刀具磨损的特征信号 ,讨论了特征信号随着刀具磨损量增加的变化规律 ,并将各个特征信号构成的特征矢量输入多层反传神经网络进行融合 ,实现钻削过程刀具磨损量的智能识别。试验结果表明该方法能有效实现多特征融合 ,但识别精度和推广能力有待进一步提高     

步进扫描光刻机硅片台连续扫描时间优化算法

为减少步进扫描光刻机连续曝光扫描运动的扫描过渡时间(扫描时间和步进时间),将硅片台扫描方向曝光扫描运动分解为逻辑步进运动和逻辑扫描运动,提出扫描和步进运动时间重叠的轨迹规划算法(时间重叠算法)处理连续曝光扫描运动。在不破坏运动约束条件下(恒速运动要求以及速度、加速度边界限制),根据时间重叠算法重新计算并推导不同扫描运动路径下连续扫描运动过程的步进和扫描运动转折点。经理论分析和硅片曝光场连续曝光实例计算表明：基于时间重叠算法的轨迹规划可获得时间优化的硅片台连续曝光扫描,比传统扫描方法减少曝光扫描运动过程中的无效率时间,提高步进扫描光刻机生产率,为步进扫描光刻机工程实践提供理论基础。     

On modeling of tool wear using sensor fusion and polynomial classifiers

With increased global competition, the manufacturing sector is vigorously working on enhancing the efficiency of manufacturing processes in terms of cost, quality, and environmental impact. This work presents a novel approach to model and predict cutting tool wear using statistical signal analysis, pattern recognition, and sensor fusion. The data are acquired from two sources: an acoustic emission sensor (AE) and a tool post dynamometer. The pattern recognition used here is based on two methods: Artificial Neural Networks (ANN) and Polynomial Classifiers (PC). Cutting tool wear values predicted by neural network (ANN) and polynomial classifiers (PC) are compared. For the case study presented, PC proved to significantly reduce the required training time compared to that required by an ANN without compromising the prediction accuracy. The predicted results compared well with the measured tool wear values.     

刀具寿命诊断的神经网络技术

提出了一种刀具寿命的检测方法。该方法把模糊逻辑和神经网络结合起来，并用神经网络分解技术，建立了一上刀具状态识别网络。该网络适于进行多传感器刀具复杂状态的识别和分类，具有训练时间短，扫行速度快，可靠性高，抗噪能力强的特点。     

A co-processor design to accelerate sequential monocular SLAM EKF process

Extended Kalman Filter (EKF) is a non-linear state estimation technique which is used to produce values that close to the true value when given with measurement containing noise and other inaccuracies. In Monocular Simultaneous Localization and Mapping (SLAM), EKF is used to estimate position and motion information. In this paper, Monocular SLAM software implementation on a general purpose computer is studied to find the most time consuming part of the estimation program. The analysis concentrates on the Monocular SLAM EKF estimation process which involves prediction, measurement prediction, matching and update. For this purpose, a form of dynamic programming analysis tool called software profiling is utilized to determine which section of the estimation program demands the highest processing time. Based on the analysis, it is found that EKF “matching” process contribute to the highest computation time. The reason behind the time-consuming process is because for every predicted feature in the matching stage, the acceptance region and their cross correlation have to be calculated. In a typical general purpose computer software implementation, the processing is limited to sequences of operations (i.e. sequential processing). Such implementation will delay the next process until the prior process completed. However, further analysis conducted in this paper shows that each feature does not depend on the prior process and can be processed individually. This would allow several features to be processed simultaneously to improve the execution speed. Therefore, an FPGA pipelined and parallel processing architecture is proposed.     

数控机床与微机间新型网络通讯系统

基于Win32串行通信原理，利用RS232串口实现了计算机与数控机床之间的文件传输。针对RS232只能实现单点式串行通讯，并且通讯距离较短的缺点，利用现场总线实现了一机程控多台数控机床的网络通讯系统，并延长了数控机床与微机间的通讯距离。     

基于激光扫描的铁谱全谱定量分析系统研究

介绍了最新研制的一种基于激光扫描的铁谱全谱分析系统的工作原理、总体结构和应用实例。该系统利用旋转漏斗结合高梯度磁场制备磨屑的沉积谱片,依靠高精度激光传感器和自动检测装置实现铁谱片的全谱检测,并实时进行数据显示和计算机采集。利用故障诊断软件对全谱数据及其它指标数据进行综合分析,参考设备库和故障库,生成磨损监测和故障诊断报告。     

基于物理属性建模的虚拟汽车碰撞问题的求解

建立了基本物理量的计算机模型，介绍了虚拟环境中建立刚体模型的方法，并以虚拟汽车为例，对其碰撞分析物理属性建模和求解。     

浅谈局域网的维护

随着计算机技术、信息技术的高速发展,网络已被各个单位作为自己获取资源、共享资源的最好工具,局域网作为一种计算机网络,在网络协议上基本符合OSI模型,该网络采用TCP/IP技术,实现数据的传输和处理功能.文章重点讨论了局域网的维护,可供计算机网络维护人员参考.     

基于网络的气相色谱仪远程操控系统设计

现代气相色谱仪器大部分都使用仪器上配备的物理人机界面直接操控仪器。本文设计了一种用于气要色谱仪的远程操控系统,通过互联通信技术,可以在任意时间、任意地点对通信网内的仪器设备进行远程实时控制,完成传统仪器中使用本地人机界面进行的所有操控功能。结合中端气相色谱仪器开发项目中的软键盘系统,从通信网络选择、仪器固件及远端控制软件等方面,阐述了远程操控系统的设计与应用。     

Integration of industrial photogrammetry and neuro-fuzzy system for measuring and modeling deformation of industrial product surfaces under external forces

Deformation of surfaces under external loadings greatly is function of physical laws. But according to the impossibility of identifying all effective factors and modeling their interactions parametrically, analytical methods do not provide good performance generally. So, it is necessary to apply practical methods by carrying out field tests and measuring deformations directly. To achieve this purpose it is required to integrate capabilities of an accurate measurement technique and a flexible modeling method. The capabilities such as: high accuracy and speed in measuring 3D coordinates of desired points, ability to perform measurement in a continuous space and no need to contact with the surface of objects at the time of measurement make close range photogrammetry a reliable tool for measuring geometric parameters of an object before and after deformation. The ability to measure geometric parameters of an object before and after deformation in one hand and following the deformation from physical laws on the other hand make neuro-fuzzy system the first choice for modeling the deformation of objects using outputs of close range photogrammetry.In this paper, a new method has been presented for measuring and modeling deformation of industrial product surfaces under external forces using close range photogrammetry (as an image-based measurement tool) and neuro-fuzzy network (as a behavior modeling tool).     

Computation of helical or spur gear fillets

This paper presents an algorithm for computing the form of helical or spur gear fillets on a digital computer. These types of tools are considered to generate the fillet: rack-type tool (hob, rack cutter, or grinding wheel) with or without a protruberance, shaper cutter, and shaving tool. Formulae for the coordinates of the fillet are derived and the boundary points of the fillet are determined both for non-undercut and undercut gearing. Flow diagrams for the solution of some difficult problems are given.     

Modelling the tooth flanks of hobbed gears in the CAD environment

The paper presents the computer simulation methodology of modelling tooth flanks of cylindrical gears. The modelling consists of a computer simulation of a gear generation. A model of tooth flanks is an envelope curve of a family of envelopes that originate from the rolling motion of a solid tool model in relation to a solid model of the cylindrical gear. The surface stereometry and topography of the tooth flanks, hobbed, are compared to their numerical models. A computer simulation of the gear generation was performed in a mechanical desktop environment.