三芯电缆载流量及温度场计算的有限元法

针对直埋方式的三芯交联聚乙烯（XLPE）电力电缆利用有限元法能任意布置结点和网格的特点,建立了地下电缆温度场计算模型,阐述了其计算原理.通过实例计算结果与实验数据对比表明,采用有限元法分析电力电缆载流量和温度场切实可行,且计算精确度高.     

Enhancing formation and retention of hollow structural integrity through intermediate and outermost layer design in seeded emulsion polymerization of hollow latex particles

The synthesis of hollow latex particles through seeded emulsion polymerization involves a series of intricate steps, including the formation of distinct polymer layers with specific properties. Despite extensive research, preserving the desired hollow structure remains challenging due to the unclear role of the encapsulating polymer layers. This study systematically adjusts the glass transition temperature (T_g) of the intermediate layer by varying the butyl acrylate (BA) ratio in the monomer feed mixture. By controlling the reaction temperature during alkali swelling, we explore the critical influence of T_g on hollow latex particle formation from carboxylated core latex particles. To ensure long-term hollow structure retention after drying, a rigid outer layer is polymerized onto the intermediate layer. Surprisingly, higher divinylbenzene (DVB) mass ratios (5.0 and 10.0 wt%) do not result in a highly crosslinked hollow shell due to DVB self-nucleation. This paper emphasizes the importance of precise design parameters for both intermediate and outermost layers in achieving and maintaining hollow latex particle structures. Understanding each layer's role and optimizing their compositions contribute to advancing hollow latex particle synthesis through seeded emulsion polymerization.     

官地水轮发电机定子铁心安装工艺

介绍了具有斜立筋结构的水轮发电机定子铁心安装工艺,分析了定子机座和定子铁心的结构特点。对铁心叠装定位的确定、各项叠装工艺参数的合理选择及叠装过程中的难点进行了阐述,并给出了具体的工艺措施。实际运行表明,该定子铁心安装工艺切实可行,各项验收指标优良。     

一种异形导体模具设计的简单方法

介绍一种设计异型导体模具的简单方法,通过借助计算机绘图软件,可以简单、准确、快速地进行模具的配制,同时,也可以计算出相应的成缆直径,从而能快速地求出电缆制造中其它辅料的用量。     

共铁芯式电炉变压器新型中性点横差保护

提出并论述了共铁芯式主调合一的电炉变压器中性点端子经简单改接可实现新型中性点横差保护。当共铁芯式主调合一的电炉变压器发生高压绕组匝间短路、同相2个分支绕组之间短路、不同相之间的相间短路、单相接地短路以及中低压绕组匝间短路和相间短路时,中性点横差保护都能快速动作跳开高压侧断路器。该保护的优点是:一种保护能保护多种类型的短路故障且动作灵敏度高,保护匝间短路的灵敏度远高于纵差保护,且简单可靠。     

Displacement fields around 1/2[111] screw dislocations in bcc metals and their defocus convergent-beam electron diffraction patterns

Displacement fields have been calculated around 1/2[111] screw dislocations with various types of core structures in bcc metals. Three types of cores are studied: two types of polarized cores with large and small extensions of the displacement fields and an isotropic core. The difference in the displacement along the [111] direction Δu_z from that for the elastic solution has been evaluated for each type of dislocation. In the outside of the core region, the Δu_z values are close to zero along the six directions and the regions with Δu_z>0 and Δu_z<0 are alternately arranged, lying between those directions. Appreciable difference in Δu_z has been detected between the polarized cores and the isotropic core up to large distance from the core region. The defocus convergent-beam electron diffraction patterns have been calculated for the dislocations with the incident beam parallel to the dislocation line. Winding and spiral features have been shown in the higher-order Laue zone (HOLZ) lines for the dislocated structures, which have been confirmed by a preliminary experiment. In addition, small shifts of the HOLZ lines have been shown by the calculation between the polarized cores and the isotropic one.     

磁性不锈钢丝编织铠装损耗的实验研究

本文介绍了上海电缆研究所对单芯交联聚乙烯电力电缆的磁性不锈钢丝编织铠装损耗开展的实验研究和理论计算 ,证明磁性不锈钢丝编织铠装的损耗可达铜损耗的 1 .9倍 ,降低了电缆允许的载流量。该实验研究为工程应用提供了依据     

Comparative study of decision tree classifier and best first tree classifier for fault diagnosis of automobile hydraulic brake system using statistical features

Hydraulic brakes are the most important components in automobile. It requires advanced supervision and fault diagnosis to improve the safety of passenger, reliability and economy. Condition monitoring is one of the major division through which the reliability of such components could be monitored. The condition of the brake components can be monitored by using the vibration characteristics which will reveal the condition of the brake systems. In this paper machine learning algorithm using vibration monitoring is proposed as a possible solution to this problem. From the hydraulic brake test set up, the vibration signals were acquired by using a piezoelectric transducer and data acquisition system. C4.5 decision tree algorithm was used to extract statistical features from vibration signals. Feature selection was also carried out. Since no much of methodologies are available to find the effective number of features for a given problem, a detailed study is needed to find the best possible number of features. Hence the effect of number of features was studied by using decision tree. The selected features were classified using C4.5 decision tree algorithm and Best first decision tree algorithm with pre pruning and post pruning techniques. The results are discussed and conclusions of the study are presented.     

泥质砂岩中束缚水的介电特性

泥质砂岩“双水模型”只讨论了束缚水和自由水在导电响应上的差异,本文对泥质砂岩介电响应机理进行分析,说明了粘土颗粒表面的束缚水和自由水在介电响应上的差异。另外,在大量实验测量的基础上,计算得到束缚水的复介电常数值,结果表明理论分析和实验测量是一致的。利用上述理论和实验研究结果修正了电磁波测井的解释模型,并将该模型用于实际测井资料解释,求得的冲洗带残余油饱和度(S_(or))和束缚水饱和度(S_(wirr))与取心分析值符合较好。依据上述理论和实验分析提出了电磁波测井资料解释应用的新领域。     

微悬浮乳液堵调剂性能研究

生产实践证实,常规化学堵调剂对层间渗透率级差大于3的地层不能达到理想的调剖和堵水效果.以油溶性树脂为主剂,并添加乳化剂、稳定剂及其他助剂,经乳化机剪切和乳化后,制备成粒径为1～5 μm且性能稳定的水包油微悬浮乳液堵调剂.通过实验确定了该堵调剂的最佳配方：50％～60％（表示质量浓度,以下同）树脂＋0.35％～0.40％十八烷基三甲基氯化铵或0.35％～0.40％十二烷基苯磺酸钠＋0.1％羟甲基纤维素＋0.10％～0.15％氯化钙＋1％～5％石蜡＋水;同时还确定了针对该堵调剂的破乳配方,即当乳化剂为十八烷基三甲基氯化铵时,破乳剂宜选用质量浓度为2％～3％的氢氧化钠水溶液,当乳化剂为十二烷基苯磺酸钠时,破乳剂宜选用质量浓度为3％～5％的氯化钙水溶液.通过对微悬浮乳液堵调剂的油溶率、酸溶率和粒径等各项指标进行性能测试,结果反映出该堵调剂具有良好的选择性及注入性.岩心驱替实验结果表明,该堵调剂的突破压力梯度达26 MPa/m,堵水率大于97％,耐水冲刷性能优于常规凝胶,并且适用于渗透率级差为7的岩心.