Morphologies of epitaxial islands on a lattice-misfitted substrate

Under certain growth conditions for systems with a film/substrate lattice misfit, the deposited material is known to aggregate into island-like shapes. We have obtained an analytical expression of the total free energy, which consists of strain energy, surface energy and interfacial energy of a coherent island/substrate system, and the change of equilibrium aspect ratio versus the volume of the island and the misfit of lattices in the system, which provides a broad perspective on island behaviour. These then were used to study the equilibrium shapes of the system. The results show that in order to minimize the total free energy, a coherent island will have a particular height-to-width aspect ratio, called equilibrium aspect ratio, that is a function of the island volume and misfit. The aspect ratio is increased with increasing island volume at a fixed misfit, and with increasing misfit strain between the island and substrate at a fixed island volume. Moreover, the effect of misfit dislocation on the equilibrium shape of the island is also examined. The results obtained are in good agreement with experiment of observations and thus can serve as a basis for interpreting the experiments.     

粉尘云电火花最小点火能的统计分析

基于统计分析的Logistic回归模型,应用以概率表示粉尘云最小点火能的计算方法,在容积为1.28L的Mike 3管内对不同浓度的烟酸粉尘-空气混合物进行了最小点火能测试实验,利用SPSS软件计算得到了各浓度下烟酸粉尘云点火成功概率为10%和50%时的最小点火能。结果表明,烟酸粉尘云最小点火能随浓度的增大呈现先减小后增大的趋势,最后保持在一定的能量范围内。与其他标准的计算结果相比,这种方法给出的结果更符合实际情况,也能满足不同生产环境对安全控制的需要。     

比色高温传感器参数分析及其在爆炸场中的应用

基于比色测温原理,系统分析了中心波长、波长带宽、立体角等因素对仪器响应速度和测温精度的影响,确定了适用于瞬态高温测量的系统参数。提出了基于光电转换系数和工作波长上下极限的比色高温传感器响应计算方法。在优化的标定温度下,用高温黑体炉进行标定实验,通过对标定数据的分析确定了仪器实际工作参数,并对传感器温度响应进行了计算。结果表明用该方法计算得到的响应关系误差在1%以内。利用该比色高温计现场测试了燃料空气爆炸场的瞬态温度响应,得到了爆轰区温度随时间、距离的变化规律。     

爆炸场瞬态高温测试的实验研究

针对爆炸场瞬态高温测量需求,从辐射测温原理出发,建立红外比色测温系统。通过黑体炉实验标定出Si/Ge双通道比色测温仪的波长、带宽、光电转换系数等工作参数和测温范围,并将比色测温仪高温测温量程扩展至3 500℃。利用大能量电火花放电产生的爆炸场标定了测温仪的响应时间,结果显示测温仪响应时间不超过10μs。确定了标准测温仪和超限测温仪的温度计算公式,并将比色测温仪应用于TNT柱状炸药和云爆剂（FAE）爆炸场温度测试,可以为爆炸反应过程诊断和爆炸温度毁伤效应评估提供依据。