Gas hold-up, mixing time and gas-liquid volumetric mass transfer coefficient of various multiple-impeller configurations: Rushton turbine, pitched blade and techmix impeller and their combinations

Gas hold-up, mixing intensity of dispersion characterised by exchange flows between adjacent impellers and a volumetric mass transfer coefficient are presented for 18 impeller configurations in triple-impeller vessel of inner diameter . Rushton Turbines, six Pitched Blade impellers pumping down and hydrofoil impellers Techmix 335 (Techmix co., Czech republic) pumping up or down and their combinations were used. aqueous solution was used as a liquid phase, which represents non-coalescent batches. Gas hold-ups and volumetric mass transfer coefficients are presented for individual configurations as functions of specific power dissipated and superficial gas velocity. The regression of the mass transfer coefficients shows large standard deviation (30%). The power number included to the regression to express the impeller configuration effect did not improve the standard deviation significantly (23%). The impeller configurations with low power number (less than unity) provide higher dispersion mixing intensities, while the impeller configurations with high power number provide better mass transfer performance.     

1991—1992国外工程塑料进展

介绍了1991～1992年国外工程塑料研究和生产概况。论述了通用工程塑料、特种工程塑料和聚合物合金的研究开发、改性和应用方面的进展。且指出工程塑料发展趋势和特点;对复合材料技术进展作了较详尽的分析与阐述。     

塑料充模流动粘性模型研究

对多种塑料在不同温度下的剪切速率一稳态剪切粘度数据进行Cross粘性模型参数拟合，得到了表征材料粘度的模型参数(B，Tb，τ^*，n)。其拟合效果良好，能较准确地描述塑料熔体在一定剪切速率和温度范围内的粘流特性，为工程计算和塑料熔体模流分析提供了数据支持。结果表明，该方法有较广泛的适用性。     

国外挤出成型加工技术及设备的近期进展

简要评述了国外塑料挤出成型加工技术及设备的近期进展,重点介绍了混炼挤出技术及设备、反应挤出技术及设备以及共挤出成型及设备的发展动向,并列举了国外主要公司的技术成果.     

赫司特赛拉尼斯公司及其聚甲醛产品celcon■

公司发展简史和共聚甲醛的标准品级以及特殊品级。     

稀土塑料助剂开发与应用研究进展

稀土元素具有特殊的电子结构和独特的物理 化学特性,已获得广泛的应用。近年来的研究显示,稀土化合物在改进塑料加工、使用性能及赋予其新功能等方面也具有独特而显著的功效并具有毒性低的优点。综述了稀土化合物作为塑料热稳定剂、填充改性剂、偶联剂、光敏催化剂、转光剂以及彩色颜料应用的研究进展。     

水滴形歧管的结构分析

本文就衣架式模头水滴形歧管的结构设计，根据聚合物加工的流变理论，结合生产实际对水滴形截面的歧管流道分配系统进行分析，使得所设计的挤塑模在尽可能高的流速下，生产出符合尺寸及形状公差的均质片材。     

Probabilistic and interval reliability design of the composite pressure vessel

Considering the randomness or interval character of physical parameters and applied loads of composite pressure vessels (COPV), the COPV reliability-analyzing model is built. And then the computational expressions for the mean value, standard deviation and deviation of fiber stress are deduced by the random factor method. The probabilistic and interval reliability designs on COPV are implemented by utilizing the probabilistic method and interval method combined with the improved particle swarm optimization (PSO) algorithm, respectively. The influence of fluctuation of structure uncertain parameters on COPV design thickness is inspected. Finally, examples are given to demonstrate that both probabilistic and interval reliability methods can satisfy the safety requirement and both are of higher rationality than the traditional safety factor method. And probabilistic method has a lower relative error but a higher computational complexity contrasted with the interval method.     

厚壁变换炉的焊接

壁厚132mm的高温高压容器“二段变换炉”用国外材料制造，焊接过程采用手工电弧焊打底 埋弧自动焊的工艺方法，取得了较好的效果。     

面向海洋通信网络的分布式系统容错机制

针对在船队航行过程中,由于网络通信不稳定引起的P2 P分布式系统节点频发的退出问题,通过优化P2 P分布式架构的容错策略,提高系统的抗灾能力。探讨并设计在海洋环境下分布式系统的容错机制,提出更加适用于全新容错机制的节点选举方法,提高节点选举的可靠性和稳定性。在优化的P2 P架构下,设计并实现基于船队出海环境的分布式数据平台原型系统。通过仿真实验证明该系统具有较好的可伸缩性、独立性和稳定性。