天然像胶的环氧化改性与表征

以有机过乙酸为环氧化试剂，在天然橡胶乳中实施环氧化反应，可达高环氧化程度，获得不同环氧化程度的环氧天然橡胶（ＥＮＲ）。并通过红外光谱（ＩＲ），差示扫描量热分析（ＤＳＣ），核磁共振（１３ＣＮＭＲ）测量等手段对产物作了全面分析和表征。结果表明，本研究得到的天然橡胶的环氧化改性物是无规共聚物，环氧化反应基本按化学计量进行，改性物的环氧化程度可以用ＤＳＣ法间接测定。环氧化天然橡胶具有优良的耐油性和气密性。     

正齿轮压力角的有效设计区间

为了不同的特殊用途，已经设计出了各种类型的正齿轮，但压力角在设计过程中起着重要的任用。本文运用极角函数来描述正齿轮压力角的有效设计区间。凸曲一，直线，凹曲线是齿的三个基本要素，在主动齿轮，被动齿轮的齿条的设计中都占有适当的区间。配对齿轮的设计区间是由它们各自的设计区间交叉而构成的。对每个设计区间的出现尖点的可能性也做了研究。     

角焊趾处表面裂纹的疲劳分析

本篇论文主要研究了钢板的角焊接肩或角焊接接头的应力集中区域内半椭圆形裂纹的疲劳扩展和结合特性。疲劳试验对象是带有类似于角焊接头的角焊缝机加工钢板试样。我们在这些试样的角焊趾处预先设置了一个和多个同面半椭圆表面裂纹，应用有限单元应力分析法解得角焊趾几何形状的近似修正系数ＭＫ等、并运用一个分析模型来模拟多相同面半椭圆形裂纹的扩展至疲劳破坏。     

Effect of animal sex and size on effort when pelting lambs

Pelting load data were collected and analysed for 304 lambs (comprising 46% ewes, 26% cryptorchids and 28% rams), all of which came from one farm. Although typically about 24% more impulse (Ns) had to be applied for pelting ram lambs than for ewe or cryptorchid lambs, only one-third of this increase was attributable to the distinct sexual category of rams; the rest was due to rams being heavier. Carcass size had a much greater effect on pelting load than animal sex: a change in dressed carcass weight of slightly less than 1 kg has the same effect on impulse requirement as the net sex effect. These findings suggest that the differences in pelting effort associated with animal sex are of relatively minor significance compared with the large differences occurring over the range of lamb size normally processed.