基于分子动力学的β-HMX结晶形貌预测

为了研究温度对β型奥克托今(β-HMX)晶体结晶形貌的影响,在二甲基亚砜(DMSO)溶剂体系中,基于分子动力学模拟方法,采用修正后的附着能模型,分别模拟了298K、328K、358K、388K和418K条件下β-HMX晶体的晶习、能量和晶体形貌。结果表明:温度对HMX的晶体形貌有显著影响。不同晶面受温度影响的程度不同,(10-1)和(020)晶面生长易受温度影响。(10-1)晶面的修正附着能绝对值最大,晶面生长速率最快,相对于其他晶面趋于消失,最终在HMX晶体中无法保留;(020)晶面的修正附着能绝对值最小,晶面生长速率最慢,最终使该晶面在HMX形貌中显露出来。

Quick selection of aluminum galvanic anodes in oil brine via galvanic current

According to dynamics of coupled galvanic anode with carbon steel,the integral of galvanic current vs.time is approximately equal to actual current capacity of galvanic anode.Galvanic current of cast aluminum galvanic anode coupled with carbon steel is tested in3.5%NaCl solution and ambient temperature.Rapid evaluation the performance of galvanic anode using galvanic current is feasible,and the test time is20min.The galvanic current is used to select aluminum galvanic anodes in oil brine,and then test the galvanic anodes with impressed current test method.The result shows,the performance of galvanic anodes degrads in oil brine,but has not much difference in the two media to the preferable anodes,and the optimal galvanic anode is gained.

GIS技术在高难山地直升机起降点选址中的应用

高难山地直升机临时起降点选址困难,可以在起降点选址中引入GIS技术。文章以DEM数据为主要研究对象,以临时起降点场地技术要求为选点约束条件,以GIS空间分析技术为依托,研究高难山地临时起降点选点技术流程和方法。结果表明,研究方法可以大幅提高选址的合理性、安全性和成功率,为类似作业所需临时起降点场地要求建立和优化选址提供参考。