Melt processable conducting poly(aniline‐co‐o‐anisidine)/linear low‐density polyethylene composites with ethylene‐acrylic acid copolymer as compatibilizer

Conducting composites of aniline/o‐anisidine copolymer doped by dodecylbenzenesulfonic acid (P(An‐co‐oAs)‐DBSA), linear low‐density polyethylene (LLDPE), and ethylene–acrylic acid copolymer (EAA) as compatibilizer were prepared by melt processing. The effects of composition on electrical conductivity, resistivity‐temperature characteristic, and mechanical properties were also investigated. The electrical conductivity of ternary composites markedly increased due to compatibilizition and protonation effect of the EAA. The SEM micrograph shows that the compatibility between the P(An‐co‐oAs)‐DBSA and the LLDPE matrix is enhanced after the introduction of EAA. The positive temperature coefficient of resistivity characteristic is observed. Tensile strength of P(An‐co‐oAs)‐DBSA/LLDPE/EAA composites is improved, compared with P(An‐co‐oAs)‐DBSA/LLDPE composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1511–1516, 2005     

CF4/CO2混合气体工频击穿特性的试验研究

SF₆是目前电气设备中广泛使用的气体绝缘介质,但其产生的温室效应对环境影响极大,因此,研究能替代SF₆的环保型气体绝缘介质具有重要的意义。CF₄是一种具有低温室效应指数（global warming potential, GWP）和低液化温度的强电负性气体。通过工频击穿试验,研究了CF₄/CO₂混合气体的工频击穿特性,并对其协同效应和GWP值进行分析。结果表明：CF₄混合比为50%的CF₄/CO₂混合气体的绝缘强度能达到纯CF₄的90%左右,同时GWP值低,具有用于气体绝缘的潜力;CF₄/CO₂混合气体的协同效应值在0.12~0.38,表现出明显的协同效应。     

火电厂锅炉送风机的选型

分析了火电厂锅炉送风机的特点,指出了送风机选型中应该注意的问题,从调节特性、运行效率、设备投资3个方面分析比较了离心风机、静叶可调轴流风机和动叶可调轴流风机的特点,提出了200MW及以下机组选用离心风机,300MW及以上机组选用动叶可调轴流风机的建议.     

Numerical investigation and improvement strategy of flow characteristics inside supersonic separator

In order to study the flow behavior and optimize separation performance, a three-dimensional numerical model of an improved supersonic separator was developed. The proposed model takes into account the compressible and strong swirling effect. Four widely-used turbulence models include Sparlart–Allmaras model, realizable k–ε model, shear-stress transport (SST) k–ω model, and Reynolds stress model (RSM) were validated and compared by the experimental date reported in the literature. The comparison results indicated that RSMs have great potential to predict the flow inside supersonic separator. Based on the established numerical model, the distribution of critical parameters such as temperature, pressure, and Mach number was obtained. The influence of the pressure loss ratio on the shockwave location occurred at the divergence section of the Laval nozzle was systematically studied. Analysis about the relationship between the pressure effect and shock wave location was carried out to explore the principal factors that limit the performance of the supersonic separator.     

Al-Zn-Mg合金价电子理论研究

在电子结构上揭示Al-Zn-Mg合金时效强化机理,利用"固体与分子经验电子"理论中的键距差法,计算了Al-Zn-Mg合金中的过饱和固溶体,GP区,η相(MgZn2)以及T相(Al2Mg3Zn3)的电子结构,从而在价电子结构上解释Al-Zn-Mg合金在时效过程中GP区和η(MgZn2)稳定相对合金强化的原因,以及高温过时效时合金强度降低的原因。     

工程投标报价的策略分析与方法

目前招投标已成为我国工程项目产品交易的主要方式,建筑企业如何编制高质量的投标书,确定科学合理的投标报价,提高投标项目的中标率和中标质量,是建筑企业生存与不断发展的关键问题。本文结合投标报价的实际情况,通过对投标报价的程序、投标各阶段应重点做好的工作进行分析,指导企业综合考虑各方面的因素,掌握投标报价的决策、策略与技巧,为企业提高中标率指明了方向。     

逆变型分布式电源T接线路后纵联差动保护的改进方案

当逆变型分布式电源(distributed generation,DG)以T接的方式接入高压配电网时,仅依靠提高电流纵联差动保护的整定值可能导致保护拒动。首先分析了逆变型DG的接入对电流纵联差动保护带来的影响。然后,利用线路母线电压互感器的信息,提出了以线路两端正序补偿电压的差值作为辅助判据的解决方案,并利用正序补偿电压和正序差动电流的相位关系消除动作死区。该方案简单易行,能够实现全线速动,并且不受DG容量、过渡电阻及两侧系统电势相角差等因素的影响。最后,基于PSCAD仿真平台搭建了含逆变型DG的110 k V高压配电网模型,对传统的电流纵差保护及改进的纵差保护进行了对比,验证了改进后保护方案的可靠性和有效性。     

我国木材工业用胶粘剂的现状、存在问题及对策

本文介绍了脲醛树脂胶粘剂、酚醛树脂胶粘剂、三聚氰胺甲醛树脂胶粘剂、聚醋酸乙烯乳液胶粘剂、聚氨酯胶粘剂、热熔胶粘剂等木材工业用胶粘剂的现状和研究进展。分析了目前木材工业用胶粘剂存在的问题,初步提出了解决问题的对策。     

几种云南本地木材的密实化改性研究

对四种云南本地木材的密实化改性工艺以及改性木材的力学性能和吸水性进行了研究。结果表明,采用预抽真空、热处理和电子束辐射的木材密实化改性工艺是可行的,经过改性,木材的密度、硬度和压缩强度可提高５０％～１００％,吸水性则可降低至原木材的１０％～３０％,已超过木地板优良用材西南桦的性能。     

Petri网在基于规则系统一致性问题检查中的应用

基于规则系统是目前应用较为广泛的一类专家系统,但它的知识库不易维护。本文针对基于规则系统的一致性问题,应用图形化建模工具Ｐｅｔｒｉ网的可达性概念和状态方程分析方法,提出了基于Ｐｅｔｒｉ网的一致性检查方法。文中首先对规则的三种Ｐｅｔｒｉ网表示模型进行了比较,并在含约束Ｐｅｔｒｉ网模型基础上,提出了一致性检验的命题方法,最后以实例说明该方法的实现步骤。当规则库较大时,相应的Ｐｅｔｒｉ网模型可能也会很庞