Viscoelastic Windows of Pressure-Sensitive Adhesives

A viscoelastic window (VW) concept has been proposed to identify different types of pressure-sensitive adhesives (PSA's). Such viscoelastic windows are constructed from the values of dynamic storage modulus: G' and dynamic loss modulus G' at frequencies of 10^-2 and 10² rad/sec. These frequencies are chosen because the range covers most of the time scales corresponding to the uses of PSA's at different application rates in performance tests. A four quadrant concept has also been recommended to categorize different types of PSA's based on the location of their VW's on the log-log cross plot of G' and G'. It was found that for most PSA's, the range of G' and G' at room temperature within these selected frequencies falls between 10³ and 10⁶ Pascals. The proposed four-quadrants (top-left hand quadrant of high G' and low G', top-right hand quadrant of high G' and high G', lower left hand quadrant of low G' and low G', and lower right-hand quadrant of low G' and high G') correspond respectively to (1) non-PSA or release coatings (2) high shear PSA's, (3) removable PSA's and medical PSA's and (4) quick and cold stick PSA's. It was also observed that the VW's of general purpose permanent PSA's occupy the central region which straddles part of the four quadrants.     

Applications of the 4×4 determinant method and the POLYGON ENGINE

In the first half of the paper, various types of processing pertaining to a polygon, using the 4×4 determinant theories are explained along with a new containment test algorithm of a point in a polygon. In the latter half of the paper, a general-purpose geometric processor, the POLYGON ENGINE, is presented which can deal with various types of interference problems, such as Boolean operations in solid modelling, hidden line and surface eliminations, ray tracing and so on. It is, a successor of the TRIANGLE PROCESSOR and is also based upon the 4×4 determinant theories [4–6]. While the TRIANGLE PROCESSOR processes a triangulated polygon on a triangle-by-triangle basis, the POLYGON ENGINE can treat a polygon without triangulation. The latter is expected to be more functional, more efficient and easier to use.     

部件试验模态综合的简便方法

本文将一种基于完备模态基的模态综合技术应用于子结构的试验模态综合,获得成功。这种半试验半理论的模态综合方法是一种较为简便的、要求试验工作量较小的试验模态综合法,因为它只要求测量子结构的振动模态和频率即可。数值仿真结果表明,这种简便的试验模态综合法是行之有效的。     

调质状态下40Cr钢的焊接

在合理制定焊接工艺的基础上，采用R307珠光体耐热钢焊条成功地进行40Cr钢在调质状态下的焊接，解决了通常采用25—13型奥氏体焊条焊接出现的焊缝强度低、焊接接头性能差的问题。     

Oxygen Tracer Diffusion in Vitreous Silica

Oxygen diffusion in vitreous silica glass is studied using the gas exchange technique. The tracer concentration profiles are consistent with a model based on two mechanisms, one network and the other interstitial. These processes are coupled through limited network–interstitial exchange. Nuclear reaction analysis and secondary ion mass spectrometry techniques are performed and compared. These results are compared to experiments on transport in thin silica films grown on single-crystal silicon.     

进口与国产高强度耐磨钢板的组织及力学性能

观察了进口、国产高强度耐磨钢板的组织，测试了它们的力学性能及耐磨性能。结果表明，国产准贝氏体钢耐磨板具有良好的强韧性配合，耐磨性能超过进口耐磨钢板，能够替代进口板作为高强度耐磨板。     

聚丙烯表面改性及与涂料的粘结

讨论了聚丙烯制品喷涂着色的优点及影响聚丙烯制品与涂料之间粘结强度的各种因素。综述和评价了对聚丙烯进行表面改性的必要性及各种表面改性方法。     

国外油气化探新进展

本文概述国外油气地球化学勘查的现状。在油气化探基础理论研究方面，国外学者提出了一些新的概念和认识。Ｍ．Ｄ．Ｍａｔｔｈｅｗｓ认为烃类迁移机制可分为弥散式和会聚式２类，并着重探讨了烃类通过会聚式迁移到达近地表时，其渗逸速率、气泡效应、分散相的成分和性质等对近地表层和水柱中烃类背景水平及异常形成的影响。Ｒ．Ｔｏｍｐｋｉｎｓ提出了油气藏地层电池和氧化还原房概念。有的学者对某些具体化探方法的原理提出了新的认识，如汞烃共生说等等。在油气化探应用效果方面，国外大量实例说明，应用非常规物化探之后，预测成功率明显提高，综合油气勘查是今后油气勘探的发展方向。近年有的学者将化探的微生物法扩展到储层研究，较准确地了解地下储层的性质与动态。油气化探技术虽然取得了重要进展，但在诸如烃类迁移机制、干扰因素的影响、应用领域的扩展等等问题上还有待进一步探讨和研究。     

深化内部改革 强化项目管理 走与国际接轨的道路

北京石化工程公司1994年完成设计投资额60亿元以上,取得了有史以来的最好成绩。其成绩的取得是和深化企业改革、健全矩阵式管理体制、狠抓项目管理、走与国际接轨的道路、加强精神文明建设等分不开的。