电缆截面积计算中如何确定电导系数

在煤炭企业电缆截面积选择计算当中，如何确定电导系数的大小，是一个不能忽视的问题。本文经过分析、计算、论证给出了较为合理、准确的结果，为供电设计中电缆截面积的选择计算提供了重要的依据     

电缆材料绿色化的两大指标——毒性和有害元素的检测和分析

采用了电缆材料绿色化的两大指标———毒性和有害元素含量的两种检测方法,即细胞毒性试验和电感耦合等离子体发射光谱仪法,认为这两种方法具有简便、精确、快速和省钱等优点,文中也提供了某电缆阻水膏和某种电缆护套料分别进行毒性试验和有害元素检测和分析。     

低温反相悬浮合成AA/AM共聚型吸水树脂

采用氧化还原引发体系，反相悬浮法低温合成AA／AM共聚型吸水树脂。研究了不同引发体系、单体组成、交联剂和引发剂浓度、温度、单体中和度对共聚物吸液能力的影响。与单一引发剂相比，采用复合引发体系，反应温度降低，聚合时间缩短，产物吸水速度和吸液能力高于聚丙烯酸钠，保水性略低于后者。共聚物最大吸液能力为：Q去离子水=970mL／g，Q生理盐水=129mL／g，Q人工尿=130mL／g。     

Reduction of alternating current loss in a high-TC superconducting transmission cable by means of helical pitch adjustment

We have reported that the alternating current (ac) losses in a 66 kV_rms 3-core high-T_C superconducting (HTS) transmission cable fabricated by Tokyo Electric Power Company and Sumitomo Electric Industries Ltd. are calculated correctly by using an electric-circuit model. According to the calculated results, the circumferential field losses are dominant in the total ac losses in compared with the self-field losses and the axial-field losses. The helical pitches of each layer in the HTS cable are designed to obtain almost same layer currents, which gives the minimum self-field losses. We think that the optimum helical pitches giving the minimum total losses are different from the helical pitches designed by the companies and calculate the optimum values in the condition of the same helical direction of each layer in the cable. As a result, for example, it is found that the ac loss of 2.1 W m⁻¹ cc⁻¹ at transporting 1 kA_rms can be reduced to 1.8 W m⁻¹ cc⁻¹ (about 14% reductions) after redesigning the cable with the optimum helical pitches. The optimum helical pitches are obtained for each given transport current. After redesigning, the distribution of layer currents is not uniform and the circumferential fields are reduced.     

Feasibility of a 1,400 m Span Steel Cable-Stayed Bridge

This paper describes the feasibility of 1,400 m steel cable-stayed bridges from both structural and economic viewpoints. Because the weight of a steel girder strongly affects the total cost of the bridge, the writers present a procedure to obtain a minimum weight for a girder that ensures safety against static and dynamic instabilities. For static instability, elastoplastic, finite-displacement analysis under in-plane load and elastic, finite-displacement analysis under displacement-dependent wind load are conducted; for dynamic instability, multimodal flutter analysis is carried out. It is shown that static critical wind velocity of lateral torsional buckling governs the dimension of the girder. Finally, the writers briefly compare a cable-stayed bridge with suspension bridge alternatives.     

流动注射悬浮液脉冲进样--火焰原子吸收光谱法测定中草药生地中的铁和锌

以流动注射悬浮脉冲进样－火焰原子吸收光谱法进行了中草药生地中铁和锌元素的测定，生地被干燥，粉碎，过筛后加入琼脂溶液制成悬浮液，然后用流动注射脉冲送入雾化器。实验考察了仪器工作条件，样品悬浮液制备和方法的准确性，用标准加入法测定，该法简便，快捷，测定结果与灰化法一致。     

基于遗传算法进行张弦梁结构索力识别

为识别张弦梁结构索力大小,提出了一种基于静力检测技术的索力识别方法.基于静力检测技术,定义了张弦梁结构索力识别的一般数学模型.通过分析张弦梁结构的整体受力特征,基于有限元方法提出了适用于张弦梁结构索力识别的识别模型.运用改进的遗传算法寻求问题的全局最优解,只需若干点位移实测值便可实现多个索段索力的同时识别.并编制了通用有限元计算程序,数值模拟算例验证了方法的可行性.     

0.6/1kV铝合金电缆在低压供电系统的应用注意事项

近年来铝合金电缆作为一种在某些场合可以替代铜电缆的新材料,在国内工业领域逐步有了较多的应用。因此,如何做好铝合金电缆的工程设计是一个值得讨论的问题。本文通过铝合金电缆与传统铜、铝电缆的比较,分析了它的电气性能、机械性能、连接性能、防腐性能和经济性,并结合工程实例,指出0.6/1 k V铝合金电缆在低压供电系统中的适用场合以及铜铝过渡、防腐蚀、设计选型等注意事项。     

不稳定岩层中平巷掘进的悬拱法

本文在总结先拱后墙平巷掘进经验的基础上，根据射 石力学理论和平巷掘进原理，提出了平巷掘进的悬拱法。实践证明，悬地是不稳定岩层中平巷掘进的有效施工方法。     

影响钒焙烧熟料浸出效果的研究

针对攀枝花钢铁（集团）公司西昌分公司Ｖ２Ｏ５生产中的间歇式浸出物料结块进行了研究,分析了物料结块和影响浸出的原因,提出了防止物料结块的措施和解决方法,达到了提高同率、缩短浸出时间的目的