Influence of strain rate on interpass softening

Most laboratory simulations of hot rolling involve a scaling down of the strain rate from the much higher industrial levels. This leads to slower softening between each rolling pass, for which corrections must be made. In the present work, torsion testing simulations of “warm” rod rolling were conducted on a Ti-Nb interstitial-free (IF) steel at 840 °C and 770 °C(i.e., in the ferrite range). For this purpose, “strain rate corrected” interpass times were used, in addition to the more familiar corrections for the stress. The results are compared with those obtained from simulations using uncorrected industrial interpass times. At 840 °C, simulations using corrected interpass times led to high levels of softening between the stages of rolling, thus triggering the reinitiation of cycles of dynamic recrystallization. The initially high stress level at the start of these cycles was responsible for the large differences in the pass-to-pass mean flow stress behavior, compared with that observed when using uncorrected industrial interpass times, or continuous deformations. The differences were much less pronounced at 770 °C, where the rate of softening is much slower than at 840 °C. Predictions for softening based on the Avrami equation underestimated the softening observed using the continuous and uncorrected industrial interpass time schedules and overestimated it for the corrected ones. The former is due to the occurrence of recovery, which is not addressed by the Avrami relation, while the latter is due to the precipitation that takes place during the corrected (longer) interpass times. It was also found that simulations using continuous deformations are applicable only if the interpass softening that would be expected using the corrected interpass times does not exceed about 20 pct.     

钢坯修磨金属切除率数学模型的研究

从分析修磨过程运动学和单个磨粒切削入手,建立了磨削深度与磨削过程诸参数(如工艺、材料性能、砂轮性能等)的关系表达式,从而建立起金属切除率与各单项参数的定量关系,为改善或提高修磨效率和修磨过程控制提供了有意义的根据。理论分析与实验结果吻合良好。     

XD－YES：IC功能成品率模拟器的实现

首先建立缺陷空间分布和粒径分布的模型，并讨论了缺陷通过版图产生电路错误的过程，给出了ＩＣ功能成品率模拟器ＸＤ－ＹＥＳ的实现。用ＸＤ－ＹＥＳ对微电子测试图和实际ＩＣ的功能成品率模拟和分析表明，其结果与实际符合很好，从而表明ＸＤ－ＹＥＳ的可行性和实用性。     

固载杂多酸催化剂气相催化合成乙酸丁酯的研究

在气固相反应体系中研究了酸处理膨润士固载的具有 Keggin结构的四种杂多酸在乙酸丁酯合成中的催化性能。实验结果表明 :同一载体负载不同杂多酸催化活性相似 ;不同载体负载的同一种杂多酸的催化活性与催化剂的表面酸性呈顺变关系。同时考察了反应温度 ,空速 ,酸 /醇比对催化活性的影响。在酸 /醇比为 1 ,温度为 1 2 0℃ ,空速为 3～ 5h- 1时 ,正丁醇和乙酸有较高的转化率 ,选择性接近 1 0 0 %。     

Real-time homogenous translucent material editing

This paper presents a novel method for real-time homogenous translucent material editing under fixed illumination. We consider the complete analytic BSSRDF model proposed by Jensen et al. [ [JMLH01] ], including both multiple scattering and single scattering. Our method allows the user to adjust the analytic parameters of BSSRDF and provides high-quality, real-time rendering feedback. Inspired by recently developed Precomputed Radiance Transfer (PRT) techniques, we approximate both the multiple scattering diffuse reflectance function and the single scattering exponential attenuation function in the analytic model using basis functions, so that re-computing the outgoing radiance at each vertex as parameters change reduces to simple dot products. In addition, using a non-uniform piecewise polynomial basis, we are able to achieve smaller approximation error than using bases adopted in previous PRT-based works, such as spherical harmonics and wavelets. Using hardware acceleration, we demonstrate that our system generates images comparable to [ [JMLH01] ]at real-time frame-rates.     

火灾后钢筋混凝土结构强度损伤的分析与计算

以单筋矩形截面梁为例,从分析计算构件的温度场着手,介绍了火灾后钢筋混凝土结构残余强度的计算方法,从而为确定其受损建筑物继续使用的安全性和进行加固补强提供理论依据。     

真空阴极弧离子镀类金刚石碳（DLC）膜的碳弧稳定性研究

选用氩气、氩气加氢气、氩气加乙炔等气体作为介质，石墨作为靶材进行真空阴极弧离子镀来制备类金刚石碳膜。石墨电弧有其独特的电弧特性曲线，不同气体介质对碳弧特性的影响不同，磁场的大小对电弧的稳定性有很大作用，碳弧下基片偏流随电弧电压的增加而减小，试验得到表面光滑的类金刚石碳（DLC）膜，对膜的表面进行了SEM分析。     

一种接入信息高速公路的新技术ADSL

新近出现的非对称数字用户线（ＡＤＳＬ）技术利用用户网中现有的铜双绞线提供１．５～６Ｍｂ／ｓ的下行数字信道，为接入信息高速公路提供了一条新途径，本文首次论述ＡＤＳＬ的基本概念，技术，发展现状和应用，最后论述我们对发展我国ＡＤＳＬ接入设备的几点建议。