应用PDM技术提高中小模具企业的工作效率

基于中小模具企业多品种、小批量、管理混乱的特点,利用产品数据管理(PDM)系统来提高其工作效率是很有必要的。本文根据中小型模具企业的特点提出了适合中小模具企业的需求和功能,并且指出了在中小模具企业中实施PDM系统时应该注意的问题。     

衔铁零件挤压成形工艺理论与实验研究

继电器衔铁零件是一种非对称的Z形薄壁纯铁件,其挤压工艺的凹模设计是一个难点。在构造出坯料和成型零部件的有限元模型的基础上,利用DERORM-3D软件对其进行有限元分析,得到了最优模角和最佳工作带长度,优化型腔结构,为挤压模具结构设计提供了坚实的依据。实验研究结果表明,数值模拟分析准确,模具结构设计合理。     

Synthesis of a cyclic peptide containing norlanthionine: effect of the thioether bridge on peptide conformation

Two diastereomeric analogues of ring C of nisin incorporating a novel norlanthionine residue have been synthesized via a triply orthogonal protecting group strategy. A full structural study was carried out by NMR, which elucidated the conformational properties of the two peptides and enabled the identity of each diastereoisomer to be proposed.     

快速成形技术在铸造中的应用

本文介绍了CA精密铸造技术。阐述了计算机辅助工程，包括UG的三维造型、三维设计。通过三坐标测量机的逆向工程，获得三维模型，然后通过快速成形技术，能迅速得到铸造原型；用ProCast对铸件的浇注工艺进行模拟，以优化浇注参数，消除铸造缺陷，通过模拟．对浇注系统结构进行了优化。     

Modeling water for computer graphics

Water motion is a phenomenon the full complexity of which has yet to be realized in simulation. Although a good deal of work has been done in modeling water waves, there remain interesting behaviours which have not been captured in any existing model. The variety of phenomena realizable by water is extensive, including waves, foam, bubbles, and spray. The present work is motivated by the complexity and range of phenomena possible as well as by the frequency with which such phenomena are encountered. Water motion has been extensively studied from a physical perspective. A computational model should take advantage of past work in this area. Computer scientists have incorporated some physics into models of water; however, currently existing models are incomplete. This paper considers the strengths and shortcomings of previous attempts to model water. The work involves the development of an extension and refinement of an existing microscopic model of fluid, and a formalization of some of the results of using this model. Some results of the model have been compared with the predictions due to hydrodynamic theory. Other results have been presented in the context of the situation being simulated, and the discussion hinges on observations of the real situation rather than on theory. In brief, the model displays great potential for simulation of surface waves, spray, and interactions between solid objects and fluid. The experimental work is largely able to substantiate claims as to the accuracy of the model at simulating the underlying physics.     

“十二五”模具产业技术发展指南及重点项目建议

<正>1模具产业技术发展指南模具是制造业的重要工艺装备,模具技术已成为衡量一个国家产品制造水平的重要标志之一。经过几十年的发展,我国模具技术已有很大进步,但总体来说与发达国家模具技术水平相比尚有10年以上的差距。因此,我国还需大量进口一些高技术     

匀压力线圈作用下板料的磁场力分布和变形规律

根据已失效匀压力线圈的结构参数,分析板料、线圈、外部通道的电流和磁场力分布.结果表明:基于模拟结果的电流方向与匀压力线圈的工作原理一致.提出匀压力线圈失效的原因.然后将板料上的磁场力作为边界条件输入显式分析软件ANSYS/LS-DYNA,分析板料的变形规律.     

基于KBE的汽车覆盖件冲压工艺方案设计

汽车覆盖件的冲压工艺方案设计是一个复杂且经验性强的创造性过程,需要一种支持多种知识表达模式和多智能决策技术的方法,解决工艺方案决策问题.通过以工艺特征为核心来表达知识,建立了基于KBE的覆盖件工艺知识模型,采用基于知识驱动决策树表达模式的特征转换机制来实现设计特征到工艺特征的映射,在工艺知识库的支持下完成工艺方案设计.实现了知识的多种描述形式及其应用,有效地解决了工艺方案设计中基于图形、规则及经验知识的决策判断,提高了汽车覆盖件工艺方案设计的智能化程度.     

"Pack year" smoking histories: what about patients who use loose tobacco?

Life time smoking of ready made cigarettes can be readily quantified as "pack years" smoked, but methods for measuring loose tobacco use are less well established. In this study the frequency of loose tobacco use by 247 hospital in-patients was determined; 64% were current or ex-smokers, 41.3% of whom (25.9% of participants) had smoked loose tobacco. A formula was developed for converting loose tobacco use to pack years smoked, based on the weight of tobacco in ready made cigarettes; 12.5 g or half an ounce of loose tobacco was approximately equivalent to one packet of 20 cigarettes. Using a questionnaire it was found that hospital physicians of all grades were able to convert smoking histories of ready made cigarettes, but not loose tobacco, into number of "pack years" smoked.