导叶叶片数对多相混输泵内能量损失的影响北大核心

为了提高混输泵的做功性能,降低能量损失,在不同导叶叶片数下,对多相混输泵的外特性及其内部能量损失进行分析。结果表明:当导叶叶片数为10时混输泵的外特性明显比导叶叶片数为7和8时更差,且最高效率偏向小流量工况;不同流量下,导叶叶片数为8时混输泵叶轮内的收缩损失和湍流耗散损失最小,而导叶叶片数对导叶进口的冲击损失影响很小,可不考虑其影响;在所选3组导叶叶片数下,当导叶叶片数等于8时混输泵的性能最优且流道内能量损失最小。     

50m~2立式电收尘器供电改造问题的探讨

本文对郑州铝厂水泥分厂50m~2立电收尘器供电系统的改造加以介绍,如提高变压器输出阻抗、加装保护电阻、增加火花放电频率、增加清灰作用、提高电场有效电晕功率等。结果,使除尘器除尘效率提高到99.5％,使出口排放浓度大幅度降至150～300mg/Nm~3。     

Indoor atmospheric corrosion in Cuba. A report about indoor localized corrosion

Indoor weight loss of steel, chloride, sulphur compounds and dust deposition rate were determined in six storehouses having different characteristics. Relative humidity and temperature were determined in three storehouses. A model for indoor corrosion of steel depending on time of exposure and deposition of dust, sulphur compounds and chlorides is proposed. Dust deposition plays an important role indoors. The position of the sample has also a significant influence on corrosion. Indoor corrosion aggressivity in Cuban storehouses ranges in classification IC3 and IC4 according to the new ISO proposal of indoor aggressivity.A report about the presence of localized corrosion indoors (filiform like) using a special designed sample is made.     

电感电容损耗电阻的讨论

通过对电容电感阻抗的测量，发现实验值偏离理论值。定性地分析了误差的来源，得出的结论是电感电容内部的损耗电阻随着频率的变化而变化，变化方向相反而并非相同。     

弧焊逆变电源的发展趋势分析

本文针对弧焊逆变电源中的几个关键问题，如功率开关器件的性能特点，增大输出变压器的功率，逆变电源的智能控制等，评述了当前的技术水平及今后的发展趋势。     

介质条件对核电用镍基合金传热管SCC的影响

综述了环境因素，包括温度、ＰＨ值、溶解氧、氯离子、氢、荷性碱含硫化合物以及铅等对压水堆核电站蒸汽发生器传热管用基合金材料（８００、６００、６９０合金）和腐蚀破裂（ＳＣＣ）敏感性的影响。     

靶面化合物覆盖度的计算方法研究

由溅射速率方程和反应粒子输运方程得出了靶面化合物的覆盖度。所有方程都用反应室结构参数和宏观参数表示，文中还给出了溅射沉积TiN薄膜的计算结果，结果表明与实验数相吻合，所建立的方法便于工艺优化的实施，属新的工程方法。     

多元靶碰撞级联中的粒子能量

用一种推广的幂指数散射截面求解了溅射输运方程，获得更加一般的渐近解，这个渐近解不但以Urbassek等人几年前所给出的两个解为其特殊情况，而且还为作者提出的SC解提供了新的证据，此外通过计算并分析了Vicanek等人发表的新的输运理论，发现他们所提出的转换理论结果与Monte Carlo模拟结果一致是不正确的。     

波形控制逆变CO2焊接电源关键控制信号的获取

通过分析波形控制CO2焊接过程，介绍了焊接电源空载、燃弧、短路等工作状态的判别，电流、电压、du/dt、di/dt等关键信号的获取方法，为研制波形控制CO2逆变焊机奠定了基础。     

Effect of ultrasonic power and bonding force on the bonding strength of copper ball bonds

Copper wire, serving as a cost-saving alternative to gold wire, has been used in many high-end thermosonic ball bonding applications. In this paper, the bond shear force, bond shear strength, and the ball bond diameter are adopted to evaluate the bonding quality. It is concluded that the ef/~cient ultrasonic power is needed to soften the ball to form the copper bonds with high bonding strength. However, excessive ultrasonic power would serve as a fatigue loading to weaken the bonding. Excessive or less bonding force would cause cratering in the silicon.