Modelling the process of incoming problem reports on released software products

For big software developing companies, it is important to know the amount of problems of a new software product that are expected to be reported in a period after the date of release, on a weekly basis. For each of a number of past releases, weekly data are present on the number of such reports. Based on the type of data that is present, we construct a stochastic model for the weekly number of problems to be reported. The (non‐parametric) maximum likelihood estimator for the crucial model parameter, the intensity of an inhomogeneous Poisson process, is defined. Moreover, the expectation maximization algorithm is described, which can be used to compute this estimate. The method is illustrated using simulated data. Copyright © 2004 John Wiley & Sons, Ltd.     

计算机控制光学表面抛光的磨头运动方式和参数的优化研究

对影响计算机数控抛光表面误差收敛速度的主要因素———磨头工作函数进行了详细的讨论。提出了以趋近因子作为评价磨头参数优化的参量。对目前流行的行星式磨头和平转动磨头分别作优化,给出了最佳参数组合,为提高计算机控制抛光的效率提供了理论依据。     

磁流变抛光材料去除的研究

磁流变抛光是近十年来的一种新兴的先进光学制造技术 ,它利用磁流变抛光液在梯度磁场中发生流变而形成的具有粘塑行为的柔性“小磨头”进行抛光。被抛光光学元件的材料去除是在抛光区内实现的。首先简要阐述了磁流变抛光的抛光机理 ,然后利用标准磁流变抛光液进行抛光实验。研究了磁流变抛光中几种主要工艺参数对抛光区的大小和形状以及材料去除率的影响情况。最后给出了磁流变抛光材料去除的规律。     

中小口径非球面元件加工技术的探讨

结合非球面轮廓检验和抛光工艺技术设备的研究 ,探讨了一种规范化的针对中小口径非球面元件的加工方法 ,并具体分析了实现非球面高效率批量化生产的技术途径 ,为中小非球面元件的广泛应用提供了有利的技术支持。     

金属的化学-机械抛光技术研究进展

介绍了近年来金属化学—机械抛光(CMP)技术的一些研究进展。内容包括CMP技术的实验方法进展与抛光效果的表征,CMP设备与消耗品的发展。分析了目前CMP技术存在的问题,提出了可能解决问题的一些建议。认为定量CMP速率方程的建立是解决好终点在线检测的关键之一。     

CVD金刚石厚膜的机械抛光及其残余应力的分析

较粗糙的表面是影响金刚石厚膜广泛使用的因素之一.本文对CVD金刚石厚膜进行了机械抛光的正交实验研究.实验结果表明,影响抛光效率的因素依次为抛光盘的磨粒、转速、正压力和抛光面积.采用较大粒度的磨盘,适当增加转速和压力有利于提高抛光的效率.此外用XRD方法对机械抛光前后的膜的残余应力进行了测定和对比分析,结果表明,经过机械抛光,残余拉应力明显减小.     

A Simple Method to Tune Up Screen‐Printed Carbon Electrodes Applicable to the Design of Disposable Electrochemical Sensors

We report an easy method to tune up screen‐printed carbon electrodes (SPCEs) for application in fabricating disposable electrochemical sensors. Simply by ultrasonic polishing a bare SPCE in a γ‐Al₂O₃ slurry, the surface roughness was drastically smoothed coupled with a large increase in hydrophilicity. The as‐generated micromorphology on the surface of the SPCE was found to be ideal for the immobilization of catechol to minimize the overpotential in the sensitive detection of nicotinamide adenine dinucleotide (NADH) and hydrazine. Physical characterization by both XPS and AFM studies specify that the adsorption behavior is related to the carbon surface functionalities and the trapping of γ‐Al₂O₃ on the polished‐SPCE.     

成像级CdSe中红外波片的表面处理工艺研究

本文利用改进的垂直无籽晶气相升华法生长出尺寸达Φ30×40 mm的优质硒化镉(CdSe)单晶体。解理晶体,通过X射线衍射仪测试精确的获得(001)晶面。然后定向切割、研磨、抛光,获得了尺寸为20×20×3mm~3的CdSe中红外波片初胚。以弱碱性溶液与刚玉粉的混合液作为抛光液,利用化学机械抛光法对CdSe中红外波片进行表面抛光处理。结果显示,抛光处理有效的减少了波片表面的损伤层、划痕及结构缺陷,晶片表面的粗糙度降低,在2~20μm波段透过率较高(达到70%),满足中红外波片的应用需求。     

DISPERSION OF NANODIAMOND AND ULTRA-FINE POLISHING OF QUARTZ WAFER

Mechanochemical Modification (MCM) of nanodiamond surface with DN-10 was studied in relation to the performance of nanodiamond in polishing quartz wafers. Results show that the modified nanodiamond is more stable in the pH range 8-11. A super smooth surface with an average roughness of 0.214 nm was achieved using a nanodiamond-based slurry regulated by N-(2-hydroxyethyl)ethylenediamine. It is suggested that the principal ultra-fine polishing mechanism of auartz wafer involves atom-level removal under the synergism of chemical and mechanical actions.     

A model for chemical-mechanical polishing of a material surface based on contact mechanics

A new contact-mechanics-based model for chemical-mechanical polishing is presented. According to this model, the local polish rate is controlled by the pressure distribution between features on the wafer and the polishing pad. The model uses an analysis based on the work by Greenwood to evaluate this pressure distribution taking into account pad compliance and roughness. Using the model, the effects of pattern density, applied down-force, selectivity, pad properties, etc. on the evolution of the wafer surface can be readily evaluated. The interaction between individual pad asperities and the wafer pattern is investigated in detail. It is shown that the pressure distribution between an asperity and the wafer surface is discontinuous at edges of features that have different nominal polish rates and that this pressure discontinuity dominates the polish rate and dishing of narrow features.The model is implemented as an algorithm that calculates the evolution of the profile of a set of features on the wafer during the polishing process. The model can be applied to chemical-mechanical polishing used for oxide planarization, metal damascene or shallow trench isolation.