汽车起动机电磁开关粘连故障分析及应急措施

从起动机电磁开关静触点结构、材料，动触点回位弹簧，通电方式等方面对电磁开关粘连作了系统分析；指出了静触点结构、回位弹簧弹力以及通电方式是影响电磁开关粘连的主要因素；提出镶嵌式静触点能降低成本，并能适应恶劣的使用环境；并提出了应对措施。     

光电控制电磁振动排种器的研究

针对目前排种器排种精度不高、稳定性差、排种不均匀及调整范围小的缺点，设计了一种光电控制电磁振动排种器。该排种器以PIC16F877为核心，采用光电控制技术，使得排种器每个工作循环可排1～125粒种子。该排种器每次排种粒数可由按钮开关采用2进制的方式在1～125之间任意设定，改善了其排种稳定性和排种均匀性。可以方便地调整排种量，并可根据需要单步或连续排种。试验结果表明，该排种器具有高的排种精度：单粒率大于98%，漏播率为0。     

罗布泊"耳纹"成因与电磁感应电导仪测量值相关性初探

应用EM38电磁感应电导仪测量法调查了罗布泊“耳纹”地区盐壳电导值，对干盐湖沉积物采取不同尺度和不同空间分辨率的取样与测量。研究结果表明，盐壳土壤EM38电导的各特征参数值均表现出明显的空间变异性，“耳纹”的形成和电磁感应电导所表征的物理量存在较好相关性：“耳纹”黑色区域电导值较高，白色区域电导值较低。     

土壤水分广义电磁测量方法的潜力分析

以我国具有代表性的土壤理化特性层间和空间变异资料为依据。基于广义电磁波与物质相互作用原理,分析了土壤理化特性变异对土壤介电常数、折射率、质量吸收系数等电磁特性参数的影响规律,得出了土壤介电常数的水分敏感性强而土壤的容重、质地影响小,因此土壤水分介电测量法是最具潜力的一类方法的结论。     

温度对桦木单板表面化学镀Ni—Cu—P三元合金的影响

利用化学镀方法在桦木单板表面沉积Ni—Cu—P三元合金,考查施镀温度对镀后单板表面电阻率和电磁屏蔽效能的影响,采用扫描电镜(SEM)观察镀后单板的表面形貌,利用EDS和XPS分析镀层成分,利用X射线衍射(XRD)分析镀层的组织结构,采用直拉法测定镀层与木材表面的结合强度。结果表明:当温度从80℃升高到90℃时,镀层平均表面电阻率从0.451Ω/cm2降低至0.301Ω/cm2;继续升高温度,表面电阻率小幅升高;在90℃时,施镀单板的电磁屏蔽效能在9 k Hz~1.5 GHz频段达到55~60 d B。SEM观察发现镀层连续、致密且具有金属光泽;EDS分析可知镀层中存在Ni、Cu和P元素,XPS分析可知镀层组成为Ni、Cu、P,其质量分数分别为79.84%、11.82%和8.34%;XRD分析表明镀层为微晶态结构;镀层与木材表面结合牢固。     

B-SPLINE FINITE ELEMENT METHOD IN GENERAL 2-D FIELD REGIONS

A B-spline finite etement method for solving general 2-D electromagnetic field problems is established. The B-spline bases for a general field region are constructed using the Bspline interpolation functions defined on a rectangle which contains the region. The Dirichlet boundary condition is dealt with by means of the generalized variational principle. Two numerical examples are given that show the characteristics and practical value of the method.     

Lightning Proof Performance of 500 kV Transmission Line in Chongqing Area

Considering the importance of 500 kV line and taking 500 kV transmission line in Chongqing as an example, the authors calculate lightning strike outage rate (including return stroke and lightning shielding failure) using regulation method, outage rate of return stroke using travelling wave method, and outage rate of lightning shielding failure using EGM. By comparing and analysing the calculating fesults, weakness of insulation and the area of easy to striking are found out, and corresponding improving measure is brought forward. The results show bigger gradient of lightning higher return stroke tripping, and in regulations result of accounting return stroke tripping is more closed to practical experience, accounting shielding failure rate exists obviously defect, and in EGM accounting shielding failure rate have take much factor, result is more close to practical experience.     

汽轮发电机稳态负序工况仿真模型及其对负序损耗计算结果的影响

稳态负序能力是大型汽轮发电机安全可靠运行的重要技术指标之一,而稳态负序损耗的准确计算是确定稳态负序能力的关键和基础。介绍了模拟发电机稳态负序运行工况的传统模型,针对其不足提出了一种新的不对称负载模型,并对2种模型所反映的物理机理和优缺点进行了对比分析。在此基础上,以一台1 550 MW的大型4极核能汽轮发电机为例,采用场路耦合的二维非线性时步有限元方法,结合2种仿真模型对其稳态负序损耗分别进行了计算,并对计算结果进行了详细分析。结果表明：相对于传统的负序模型,笔者提出的不对称负载模型充分考虑了磁饱和与转子附加损耗的影响,计算出的稳态负序损耗更接近实际情况,为准确考核大型汽轮发电机的稳态负序能力奠定了基础。     

The optical isolation method of suppressing electromagnetic interference of automotive ignition system

Electromagnetic radiation, which is caused by the engine ignition system, is the most powerful electromagnetic interference (EMI) source in the vehicles, as well as the main reason of most electronic control unit (ECU) malfunction. In order to reduce interference from ignition noise on ECU, we use optical isolation technology to isolate electrical connections between the interference source and the control circuit. The formation mechanism of the ignition system EMI is analyzed. The possibility of suppressing ignition system EMI with optical isolation technology is discussed. Then, as a result we design an experimental platform of suppressing ignition system EMI. The experimental results show that the effect of suppressing ignition noise, in 20~100 MHz frequency band, is obvious after applying optical isolation circuit. It can address the issue of automotive EMC.     

纳米Fe3O4/PANI复合体系的微波电磁特性研究

用原位化学反应生成法制备了纳米Fe3O4/PANI复合材料,研究了样品在2~18 GHz范围的微波电磁特性与吸收性能以及复合材料组分对电导率、密度的影响.结果表明,Fe3O4颗粒尺寸约12.7 nm,Fe3O4在复合体系中的质量分数为35%左右时,电导率最大,密度相对较低,微波吸收率最高,吸收峰值为-21 dB,-10 dB频宽大于4 GHz,样品同时具有电损耗和磁损耗.可见,通过优化设计,纳米Fe3O4/PANI复合体系可以成为一种性能优良的微波吸收材料.