轴承的可靠性分析方法

轴承在程上就用非常广泛,由于轴承作为易损件需要经常维护和更换.准确的科学地判断轴承的使用寿命, 对工业生产十分重要.文章针对工业生产中轴承出现故障的特点,建立了故障模型和可靠性函数.介绍了用威布尔分布进行分析轴承的疲劳寿命的方法,并实际计算了可靠度在0.95时轴承的使用寿命.解决了轴承在生产时比较重要的寿命问题.用威布尔分析轴承寿命是对轴承可靠性进行科学、准确的数学量化.该分析方法也可以应用到其他工程实践当中去.     

大型立式泵机组用同步电机两个高差的安装控制

电机定转子磁场中心高差和叶轮与外壳中心高差影响机组运行,分析了影响这两个高差的因素,应保证泵机组在运行状态下这两个高差满足要求,提出了高差安装确定控制方法。     

硫酸亚锡的制备方法

硫酸亚锡的制备方法可分为化学法和电化学法，在化学制备法中，用NH4HCO3作沉淀剂的氧化亚锡－硫酸合成法目前仍为制备硫酸亚锡的主要化学方法之一，锡的转化率为85.6%，产品纯度可达98％，电化学方法可制备纯度高达99％以上的产品，阴离子隔膜电解法电流效率达到了99％，节能明显，基于无污染，是一种最有前景的制备方法。     

Effect of osmotic stress on microstructure and mass transfer in onion and strawberry tissue

We investigated the structural changes in onion epidermis and strawberry cortex tissue due to osmotic stress during osmotic treatment (OT) with sucrose solutions of concentrations ranging from 300 to 600 g kg^?1. We used miniaturised experiments with confocal scanning laser microscopy (CSLM) to monitor microstructural changes—cellular shrinkage and viability—during OT. The overall cellular shrinkage of these plant tissues was not significantly different under the same conditions of osmotic stress. For onion epidermis we determined the transmembrane water flux from the cellular shrinkage and found that the coefficient of water membrane permeability was (1.0 ± 0.39) × 10^?6 mol² J^?1 m^?2 s^?1. Osmotic stress did not affect the cellular viability of onion epidermis but significantly reduced the viability of protoplasts of strawberry in the whole range of solution concentrations. We used Fick's unsteady state second‐order diffusion equation to describe cellular water transport under transient conditions. The pseudo‐diffusional approximation led to water diffusivity values in the range (3–10) × 10^?12 m² s^?1 for both onion epidermis and strawberry cortex tissue. The concentration of the solution did not significantly affect the values of effective water diffusivity, which indicated the primary role of the plasma membrane during the initial stages of OT. Copyright © 2003 Society of Chemical Industry     

ZnS基电致发光薄膜及其制备方法

ZnS是一种优良的光电材料并获得了广泛的应用。介绍了ZnS基薄膜电致发光器件的发展历史、结构及发光机理,主要讨论了ZnS基发光薄膜及蒸发法、溅射法、化学气相沉积法、外延法和溶胶-凝胶法等制备方法的最新研究进展,指出了目前存在的问题及今后的发展趋势。