单元串联式多电平高压变频器的起源、现状和展望

本文对单元串联式多电平高压变频器的起源和现状进行了总结,同时从无速度传感器矢量控制、大容量化、冗余设计等方面对该技术未来的发展趋势进行了展望。     

对印制电路板环境冲击评估的研究

随着印制电路板产业飞速发展,其引发的环境问题日益受到广泛的关注。然而长期以来如何有效地进行环境冲击评估是业内研究的重点和难点。而本文采用了一种智能的简化分析方法来进行全面的环境冲击评估,以提高评估的经济效益和准确度,并希望能为决策者提供一个可供参考的环境冲击评估的理念和方法。     

外源乙烯对黄瓜幼苗根系生长及内源多胺含量的影响

精确控制营养液溶氧浓度和外源乙烯浓度,研究了黄瓜幼苗根系在低氧水培时的生长情况以及PAs含量的变化。结果表明,外源乙烯对根际低氧逆境下黄瓜幼苗根系的生长有抑制作用,虽然根径增粗,含水量增加,但根系的总根数、总表面积、总体积、干重和鲜重都有所减少,随着乙烯浓度的增加,抑制作用增强;外源乙烯对根际低氧逆境下黄瓜幼苗根系PAs含量有着明显的拮抗作用,外源乙烯使根际低氧逆境下黄瓜幼苗根系的伤害症状加重。     

向家坝水电站右岸隧道进出口边坡的处理研究

文章主要从实践方面介绍了向家坝水电站右岸地方还建公路北线段隧道洞口施工期边坡缺陷处理措施,并总结了几点经验,这对于以后公路隧道洞口的设计和施工,尤其是洞口边坡塌方的处理具有一定指导意义。     

数值试井在白6-2井测试资料分析评价中的应用

数值试井是在近来发展的一项新的试井解释技术，具有处理非均质，复杂边界油气藏问题的优点，弥补了常规解析试井技术的不足。运用数值试井解释技术，结合动、静态资料，通过对白6-1断块白6-2井测试资料的综合分析评价，确定了储层渗流参数，落实了该气藏的边界情况，为该断块下一步开发提供可靠依据。     

企业中层管理人员培训的思考

以分析企业中层管理人员培训的现状为突破口,阐述了中层管理人员培训需求分析的思路和方法。在此基础上对培训内容进行整体设计,指出针对此类培训应采用的培训方式和评估方法。以期对企业中层管理人员的培训起到一些启发和借鉴作用。     

硫化氢吸收液的电化学分解条件研究

理想的脱硫工艺应满足体积小、费用低、净化度高、无二次污染等要求。在碱性溶液吸收微量硫化氢时同步进行电解，可有效减小设备体积，并将硫化氢转变为氢气和硫磺，不产生恶性气味。为此，实验研究了温度、浓度、电流密度、pH值等因素对电解阳极过程的影响，确定了适宜的电解条件，并在该条件下进行了吸收实验。结果表明，在最佳电解条件下，硫化钠溶液能充分吸收天然气中经变压吸附提浓的硫化氢（800 mg/m³），吸收率大于99.9％。     

Analysis of the mechanism of die soldering in aluminum die casting

A mechanism of soldering of an aluminum alloy die casting to a steel die is proposed. A soldering critical temperature is postulated, at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds. The liquid joins the die with the casting upon solidification. The critical temperature is determined by the elements in both the casting alloy and the die material and is equal to the solidus temperature of the resulting alloy. The critical temperature is used to predict the onset of die soldering, and the local liquid fraction is related to the soldering tendency. Experiments have been carried out to validate the concept and to determine the critical temperature for die soldering in an iron-aluminum system. Thermodynamic calculations are used to determine the critical temperature and soldering tendency for the cases of pure aluminum and a 380 alloy in a steel mold. Factors affecting the soldering tendency are discussed, and methods for reducing die soldering are suggested.     

用CMOS工艺实现VSR光电集成接收机的途径

介绍了10Gbit／s速率的甚短距离光传输系统VSR(Very Short Reach)中的接收机。分析了几种有希望用于VSR系统的CMOS工艺兼容的光电探测器。提出用CMOS电路实现VSR光电集成(OEIC)接收机的可能性和实现方法。     

A Study on Turbo—rotor Multi—fault Diagnosis Based on a Neural Network

The multi-fault phenomena are common in the turbo-rotor system of a liquid rocket engine.As it has many excellent qualities,the neural network might be used to solve the problems of multi-fault diagnasis of a turbo-rotor system.First,the feature expression of a common turbo-rotor fault was studied in order to build up the standard fault pattern and satisfy the need of neural network studying and diagnosing.Then.the turbo-rotor fault identification and diagnosis problems were investigated by using a BP(back-propaga-tion)neural network.According to the BP neural network problems,the parallel BP neural network method of multi-fault diagnosis and classification was presented and investigated.The results indicated that the parallel Bp neural network method could solve the turbo-rotor multi-fault diagnosis problems.