20CrNiMo牙轮牙爪锻造缺陷对力学性能的影响

KX-250三牙轮钻头上的牙轮牙爪可选用20CrNiMo钢锻造,但20CrNiMo牙轮牙爪在锻造过程中产生的缺陷严重影响产品的力学性能.为此对20CrNiMo牙轮牙爪进行质量跟踪,并对试样进行了力学性能的测试.结果表明：当锻造产生了白点和过热缺陷时,牙轮牙爪的力学性能明显下降,尤其是塑性指标和冲击韧度降低明显.为了防止这些缺陷的产生,还提出了一些对策,以提高牙轮牙爪的力学性能.     

Fine grinding of silicon wafers: a mathematical model for the chuck shape

Fine grinding of silicon wafers is a patented technology to manufacture super flat semiconductor wafers cost-effectively. Two papers on fine grinding were previously published in this journal, one discussed its uniqueness and special requirements, and the other presented the results of a designed experimental investigation. As a follow up, this paper presents a study aiming at overcoming one of the technical barriers that have hindered the widespread application of this technology, namely, the difficulty and uncertainty in chuck preparation. Although the chuck shape is critically important in fine grinding, there are no standard procedures for its preparation. Furthermore, the information on the relation between the set-up parameters and the resulting chuck shape is not readily available. In this paper, a mathematical model for the chuck shape is first developed. Then the model is used to predict the relations between the chuck shape and the set-up parameters. Finally, the results of the pilot experiments to verify the model are discussed.     

颚式破碎机破碎板结构参数研究

应用模糊随机理论确定了破碎板各齿面的破碎力,利用软件ANSYS对破碎板进行有限元分析,得到了破碎板的应力和变形云图,分析出破碎板的受力分布情况,在此基础上对破碎板结构参数进行了研究和改进,结果表明：增加破碎板凸台个数和中间凸台的宽度对改善破碎板的应力集中有明显的作用,延长了破碎板的使用寿命。     

特细碎型复摆颚式破碎机的优化设计

论述了研制特细碎型颚式破碎机的必要性意义，指出只有采用优化设计方法才有可能获得成功。文章还介绍了特细碎型颚式破碎机的优化设计方法、步骤、设计框图及研制出的两种特细型碎颚式破碎机破碎物料后所得产品颗粒的粒度曲线。     

Rumination activity of dairy cows in the 24 hours before and after calving

Monitoring rumination behavior serves multiple purposes in feeding and herd management of dairy cows. The process of calving is a major event for cows, and a detailed understanding of alterations in behavioral patterns of animals in the time around calving is important in calving detection. The objective of this study was to describe the short-term changes in rumination patterns in dairy cows immediately before and after parturition. In total, 17 cows were fitted with rumination sensors that were able to monitor rumination time, number of rumination boli, and number of rumination jaw movements. Rumination time was decreased in the last 4 h antepartum and in the first 8 h postpartum. Cows stopped ruminating 123 ± 58 min (mean ± standard deviation) before calving and resumed ruminating 355 ± 194 min after calving. The number of rumination jaw movements and boli per day were decreased in the 24-h period postpartum. Rumination rate, the number of rumination jaw movements per rumination minute, and the number of boli per rumination minute changed little around calving. The calving event primarily influenced the duration and frequency of various rumination characteristics but not rumination intensity. Among detected characteristics, rumination time showed the greatest potential for monitoring of calving events.     

79m~2沉降电炉电极装置在1.5万t镍冶炼厂的应用

对79m2沉降电炉电极装置进行分析,针对以往电炉电极装置的问题进行了改造,经两年的生产实践证明,设计合理,运行可靠,经济效益显著。     

Architectural Patents and Open-Source Architectures: The Globalisation of Spatial Design Innovations (or Learning from ‘E99’)

Patents are the strongest form of intellectual property rights available internationally, so far unbeaten by open source as a body of innovation and know-how. Mark Garcia , senior lecturer in the Department of Architecture & Landscape at the University of Greenwich, London, here considers the pros and cons of the patent system for architects in the digital age: from issues over patent categorisation by type, to possibilities of micro-royalties through the capacity of design software to track every stage of input from multiple contributors.     

颚式破碎机数字化开发平台

在Solid Works平台上采用VB及API技术开发出颚式破碎机数字化开发平台.介绍了颚式破碎机数字化开发平台的结构、专家系统在破碎机方案设计中的应用及颚式破碎机结构参数的优化设计方法.该平台集设计计算、绘图、参数优化、分析于一体,实现了并行及敏捷设计.     

复摆颚式破碎机的轴承

复摆颚式破碎机上装有两对轴承：一对轴承装在机架与偏心轴之问,通常称为机架轴承,机象军田泵支承偏心轴作叫转运动;另一对轴承装在动颚与偏心轴之间,通常称为动颚轴承,支承动颚在偏心轴回转时作摆动运动。阿对轴承将破碎机运行时的破碎物料负荷传递到机架上．是颚破机重要的零部件之一。