巨型框架多功能减振结构脉动风振的时程分析

本文以一种结构方案为算例 ,建立了巨型框架多功能减振结构及抗振结构的分析模型 ,并随机模拟了脉动风的速度时程 ,由此研究了巨型框架多功能减振结构脉动风振的位移及加速度时程反应 ,结果表明巨型框架多功能减振结构能够显著降低结构的风振反应 ,是一种较有前途的结构形式。     

Coupling monolayers for protection of microelectronic circuits

Two polymeric coatings, a silicone gel (Dow Corning 6646) and an epoxy resin (Dexter FP 4402), were glob-top coated onto representative microelectronic circuits, AT&T Triple Track Testers (TTTs), and subjected to the Pressure Cooker Test (PCT). Coupling monolayers were self- assembled on the TTTs prior to encapsulation to improve the moisture protection capabilities of the coatings. Leakage current measurements were made to evaluate the effect of applied monolayers on the moisture protection capability. The moisture protection capability was assessed in short-term and long-term leakage current measurements. MHDA (16-mercaptohexadecanoic acid) and APS (gamma-aminopropyltriethoxysilane) monolayers, in combination with silicone gel and epoxy resin respectively, exhibited very good moisture protection performance.     

Reliability of III–V based heterojunction bipolar transistors

This paper reviews the reliability of III-V based heterojunction bipolar transistors (HBTs). These devices have many potential advantages over other solid-state microwave devices. However, because of the tradeoff between performance and reliability, they are not being used to any great extent in power microwave applications. In the type of III-V HBT device most fully developed, the AlGaAs/GaAs HBT, leakage currents play a major role in the dominant mode of degradation. Because low-frequency noise is related to these leakage currents it has been used extensively in the analysis of the performance and reliability limitations of these devices. The reliability of other types of III-V HBT devices, such as InGaP/GaAs and InP based devices, is also discussed.     

Slon磁选机分选攀钢铁矿的工业试验

赣州有色冶金研究所与攀钢选钛厂合作，应用Slon-1500立环脉动高梯度磁选机进行了微细粒级钛铁矿磁选-浮选流程中磁选部分的工业试验，当给矿品位为9．23％TiO2时，经一次磁选作业，可得到含TiO2为19．58％，回收率为63．12％的良好指标，为浮选获得最终钛精矿奠定了坚实的基础。     

An experimental study of heat transfer enhancement with a pulsating flow

A pulsating flow in a pipe was experimentally investigated to determine the effect of pulsation on the rate of heat transfer. The influence of hydrodynamic parameters and characteristics of the pulsation on heat transfer was carefully studied. In order to adjust the pulsating parameters, a self‐oscillator was designed so the length of the resonator and the length of the outlet nozzle could be adjusted. The results show that the heat transfer rate is strongly affected by both the hydrodynamic parameters and the configuration of the resonator. With the increase of the flow rate of the liquid and the length of the chamber, heat transfer is enhanced. There is an optimal length at which the heat transfer enhancement attends to the best. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(5): 279–286, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20020     

综采放顶煤支架防倒防窜技术改造

对裴沟矿“三软”不稳定厚煤层综采放顶煤支架在大坡度条件下存在的倒架、支架上窜问题进行分析 ,用悬挂式提底座油缸扶倒架 ,加长调底座油缸 ,防止支架上窜 ,提高综采放顶煤的产量和工效。     

东鞍山烧结厂磁浮流程可行性的研究

选用立环脉动高梯度强磁机和新研制的新型捕收剂，东鞍山贫赤铁矿石经实验室试验，采用两段连续磨矿－强磁抛尾－混磁精再磨－正浮选工艺流程，可得到品位大于64％的精矿、铁回收率超过70％的指标。     

基于广义二阶积分器的表贴式永磁同步电机低速转子位置检测方法

在基于脉振高频电流注入的表贴式永磁同步电机无位置传感器控制中,常采用高阶滤波器来调制信号以抑制阶跃信号带来的误差。该文提出一种基于广义二阶积分器的新型转子位置观测器,由两个广义二阶积分器串联构成。前级实现高频信号提取功能,后级用于误差幅值获取。该结构有效减小了信号处理产生的延时,减轻了运算负担;同时在位置观测器中引入微分前馈控制,明显降低了动态过程中阶跃信号对位置观测器的影响;最后基于RT-LAB控制器对上述方法进行了实验,结果表明所提观测器改善了系统的控制性能。     

低压电器短路分断对自身通信的干扰机理研究

建立控制与保护开关电器(CPS)触头系统和电弧运动的数学模型,对短路电流进行仿真计算,结果与试验结果较吻合。在Maxwell仿真环境下建立了主回路导体和电缆线模型,仿真短路电流下通信电路周边的瞬态空间电磁场分布,进一步得到通信电缆产生的感应电压和感应电流。根据仿真和计算结果,给出了低压电器的设计建议。     

不同材质电缆支架对电缆运行适用性研究

在大电流作用下,电缆支架的导磁性会改变电缆周围的磁场分布,进而影响电缆本体运行,导致其温升变化,以往电力规程规范对于电缆支架的选材并未给出明确说明。文中以江苏省电力公司镇江市南徐220 kV变电站电缆为例,采用二维电磁场-流体场-温度场多物理场耦合有限元计算方法,研究不同载流量、不同电缆材质支架对电缆运行温升的影响。结果表明不同材质电缆支架因涡流引起的电缆支架温升不会危及人身及设备安全,是否选用非磁性材质支架应综合考虑涡流引起的损耗及经济性。文中考虑了电缆支架的影响,给出了支架选择时的理论与工程应用依据,对提高电缆建设经济性和运行可靠性有重要意义。