聚丙烯微孔膜研究进展

聚丙烯（PP）是一种价格低廉的塑料，是目前最主要的制备高分子微孔膜的材料之一。笔者综述了近年来PP微孔膜制备方法的研究进展，重点介绍了熔纺拉伸法（MSCS）、热致相分离法（TIPS）、共混拉伸法、熔融烧结法等PP微孔膜的常用制备方法，并对相关的影响因素进行了讨论。     

变速直驱开关磁阻风力发电系统雷电防护技术研究

根据风力发电机组防雷保护的研究成果和相关行业防雷标准,分析雷电的形成、破坏机理及其破坏形式。结合开关磁阻风力发电系统特征,划分雷电防护区域;按照风力发电机组防雷设计应该遵循的原则,通过外部防护和内部防护相结合,提出开关磁阻风力发电系统各部件防雷保护措施。为工程实践中开关磁阻风力发电系统的雷电防护提供一定的参考。     

呼吸感应体积描记系统中弱信号锁相放大模块的设计

在呼吸感应体积描记呼吸测量系统中,需要测量nV~μV级的微弱感生电压信号,而且在测量过程中,做为传感器的电感线圈容易受到测量环境,呼吸运动以外的其他运动和电子噪声等影响。为适应系统测量范围并降低噪声的影响,设计了一种基于AD630锁相放大电路微弱生理信号检测模块。该模块的锁相放大器具有大于0.96的良好线性度,能检测出传感器的感生电压信号,并分离出直流分量,有效地降低噪声对系统的影响,提高了系统测量的精度,并有望应用于其他微弱生理信号检测。     

两种新的水溶性卟啉的离解常数测定及酸碱诱导聚合

研究了ｍｅｓｏ－四卟啉和ｍｅｓｏ－四卟啉的离解常数。ＴＢＰｈＰ的离解常数为：ｐＫａ４＝１．１３．ｐＫａ３＝１．８８，ｐＫＡ２＝１２．２１；ＴＴＰＳ的离解常数为：ｐＫａ４＝４．４７，ｐＫａ３＝６．２６。外还发现了两卟啉的酸碱诱导聚合。     

海工高性能混凝土用复合胶凝材料的试验研究

在调查分析海工混凝土工程实例的基础上，试验研究了硅酸盐水泥中掺入矿粉、粉煤灰、硅灰等混合材料对海工混凝土性能的影响。研究结果表明，在硅酸盐水泥中掺加矿粉、粉煤灰、硅灰等混合材料可以改善海工混凝土的综合性能。矿物混合材料的复合掺入比单独掺入能更好地改善混凝土抗Cl^-侵蚀性能。海工专用复合胶凝材料生产时宜尽可能地采用多种混合材料。     

Preparation of rechargeable lithium batteries with poly(methyl methacrylate) based gel polymer electrolyte by <Emphasis Type="Italic">in situ</Emphasis>γ-ray irradiation-induced polymerization

An admixture of commercial liquid electrolyte (LB302, 1 M solution of LiPF₆ in 1:1 EC/DEC) and methyl methacrylate (MMA) was enclosed in CR2032 cells. The assembled cells were then -ray-irradiated using configurations of half cells and full cells. Through this in situ irradiation polymerization process, we obtained rechargeable lithium ion cells with poly(methyl methacrylate) (PMMA) based gel polymer electrolytes (GPE). Galvanostatic cycling, AC impedance spectroscopy, and cyclic voltammetry were employed to investigate the electrochemical properties of the cells and the gel polymer electrolyte. This PMMA-based gel polymer electrolyte was found to exhibit a high ionic conductivity (at least 10^–3 S cm^–1) at room temperature. Due to a significant increase in the charge transfer resistance between the GPE and the cathode, the cell impedance of a PMMA-based lithium ion cell is greater than that of a liquid-electrolyte-based cell. The discharge capacity of a LiNi_0.8Co_0.2O₂/GPE/graphite is approximately 145 mAh g^–1 for the first cycle and decreases to123 mAh g^–1 after 20 cycles. In addition, a large initial cell impedance (LICI) was observed in the irradiated positive half cell. In this paper, we propose a possible mechanism related to the detachment of the PMMA layer from the lithium electrode. This detachment of the PMMA layer from the lithium electrode has not been explicitly discussed previously.     

Hydrogen induced cracking of X80 pipeline steel

The hydrogen-induced cracking (HIC) behavior of X80 pipeline steel was studied by means of electrochemical charging, hydrogen permeation tests, tension test, and scanning electron microscopy (SEM). The experimental results indicate that the increase of charging time and charging current density or the decrease of the solution pH value leads to an increase of the hydrogen content in X80 steel, which plays a key role in the initiation and propagation of HIC. It is found that the majority of macro-inclusions w...     

均匀流场中三维陷落腔流激振荡实验研究

针对均匀流场中,三维等高型陷落腔因分离流而产生的流激振荡问题,开展了系列的实验研究.实验过程中,主要考虑来流攻角为0时,流速变化(Re=2.06×105~1.16×106)对三维陷落腔流激振荡特性的影响.同时,分别测量了三维腔体侧壁周向及垂向流体压力,分析了腔体内稳态压力和脉动压力的周口、垂向分布规律及腔口剪切层自持振荡特性.实验结果表明:均匀流场中三维陷落腔内部压力分布复杂,且当雷诺数大于某值时腔体内稳态压力全都呈现出负压,同时腔口随边处存在着较大的脉动压力,且脉动压力随相对高度增加而减小,但腔口导边及侧面处的脉动压力随相对高度增加而增大.剪切层自持振荡频率的无量纲数St数随Re变化为一常数值,但其值略大于气流场中二维陷落腔的St数.     

应力型大模面积光子晶体光纤的纤芯设计

通过施加完美匹配层,利用有限元法,研究热应力诱导的单偏振大模面积光子晶体光纤的偏振特性,计算纤芯参数对场能量分布系数和偏振损耗比的影响.结果表明,随着纤芯折射率提高,两正交偏振模的损耗比下降,当纤芯直径减小时,场能量分布系数降低.     

金属网架天线罩中金属梁杆的感应电流矩量法分析

用矩量法对金属网架天线罩中金属梁杆的感应电流率进行了理论分析,并利用此方法对导电圆柱体的感应电流率进行了仿真分析,数值仿真结果与经典方法吻合较好。针对常规矩量法在处理规则矩形柱体感应电流率中存在的问题提出了改进模型,结果可较理想地满足工程设计的需要。