Linear viscoelastic properties of mixtures of 3- and 4-arm polybutadiene stars

The viscoelastic properties of a three-arm and a four-arm star polybutadiene with the same arm molecular weight (M_a) were studied. The zero-shear recoverable compliance (J⁰_e) and plateau modulus (G⁰_N) for these stars are the same. The zero-shear viscosity (η₀) of the three-arm star is 20% lower than that of the four-arm star. Mixtures of the stars had J⁰_e and G⁰_N unchanged. A $\text{50}\text{50}$ mixture of the three- and four-arm star was diluted with a low molecular weight linear polybutadiene. G⁰_N∝ø²; J⁰_e∝ø^?1 and M_e∝ø^?1, as expected for dilution with a θ-solvent.     

太钢电弧炉上应用四星接法MOA的必要性

分析了太钢电弧炉变压器高压侧相间过电压的产生原因，比较了用于限制过电压的避雷器的两种接法．结论是用四垦接法ＭＯＡ限制过电压的效果较显著．     

不甩线圈的多星形移相变极

对于某些槽数和极数比的多星形移相变极电机,提出与前人不同的是在两种极数下均不甩去线圈的绕组方案,使绕组利用率高,且线圈及其联接都较简单.这种绕组方案在一种极数下并联支路略有不平衡,其所引起的电机定子铜耗的增加是极其有限的,不致影响电机的正常运行.     

人造导星技术及导星用激光系统

论述了自适应光学系统对人造导星的需要;简单介绍了两类激光导星;重点描述了销激光导星的产生机理及可用于销激光导星的一些激光系统.     

紧凑型边界扫描技术的功能与现状

芯片一体化进程的加剧以及对功耗控制的关注日益增加,边界扫描技术面临新的挑战,这些挑战来源于调试、应用、测试等方面,紧凑型边界扫描技术对此提出了有效的解决方法;以IEEE1149.7标准以及国内外文献报道为依据,对精简引脚与增强功能边界扫描技术的测试规范进行系统的分析,重点对该技术的新功能、新特性和新应用进行详细介绍;针对符合IEEE1149.1标准的测试系统与被测系统如何升级以实现IEEE1149.7标准新功能的问题提出了相应的建议;最后总结了该技术的发展方向和应用前景。     

Novel tin‐coupled star‐shaped medium vinyl butadiene rubber. I. Arm number and its effect on properties

To achieve low rolling resistance, high wet grip, and favorable overall performance, star‐shaped medium vinyl butadiene rubber (S‐MVBR) was designed and prepared by “core‐first” method, where novel multifunctional organolithium containing Sn atom as initiator, THF as structure regulator, and carbon–hydrogen compound as solvent. The results showed that coupling reaction between SnCl₄ and dilithium is stoichiometrical, and this method has much higher efficiency than the “arm‐first” method. When dilithium is composed of 4–10 repeating units, the average arm number of S‐MVBR is conveniently controlled between 3 and 5 by initiator functionality, which can be easily regulated by the mole ratio of active lithium of dilithium short chain to Cl^? in SnCl₄. As Sn coupling decreases numbers of noncrosslinking free ends, S‐MVBR has lower rolling resistance, dynamic heating and higher wet grip than linear MVBR. Meanwhile, mechanical properties and processing properties are improved. And the formation of multiarm structure has little effect on viscosity. S‐MVBR with arm number of 3.8 has optimal overall performance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3917–3923, 2007     

扩展双星树的 Wiener-E 指标和 Wiener-O 指标

扩展双星树（T（n）n1,n2）是 n－1长路径的两端点分别联结 n1条悬挂边和 n2条悬挂边所得到的图。论文根据扩展双星树的结构特征,研究了扩展双星树的类Wiener指数,给出了一般计算公式。     

小电流接地系统两点异相接地的故障分析

根据实际运行中发生的一起导致主变差动保护动作的故障,分析了不同接地情况下对小电流接地系统运行的影响,给出了线路电流互感器不完全星形接线时,互感器中性线断线对线路保护的影响,对调度和变电运维人员处理相关异常情况具有一定的指导意义。     

卡塞格林式星敏感器杂散光分析

卡塞格林系统是新型星敏感器的光学系统,具有口径大、体积小的优点,但外界杂散光对卡塞格林系统的影响很大。介绍了一种焦距为425mm,口径为102mm的卡塞格林系统,考虑轴外渐晕的影响,给出星敏感器主遮光罩以及主、次遮光罩的设计方法。这种设计方法相比于其他方法更加便捷和精准。并用Tracepro对系统进行杂散光分析。计算得到点源垂直照度透射比（Point Source Transmittance,PST）曲线。分析结果表明,当杂散光入射角大于临界角30°时,PST值小于10-8量级,满足系统使用要求。证明设计方法是可行的。     

星级酒店人性化财务管理目标探讨

人性化管理已逐渐提升为现代星级酒店管理的主流管理理念,星级酒店财务管理也不例外。以人性化管理为出发点,分析目前星级酒店传统财务管理目标存在的不足,提取人性化管理与财务管理目标的焦点,并就财务管理目标的制定、执行与人性化管理的结合提出了相应的策略,为企业达到价值最大化的财务目标提供有力保障。