粒度和形貌及粒度分布对RDX安全和热分解性能的影响

采用溶剂/非溶剂法和筛分法,通过控制搅拌速度及溶剂与非溶剂温度差,制备了不同粒度、形貌和粒度分布的RDX粉末。利用激光粒度仪、扫描电子显微镜(SEM)和X射线衍射(XRD)对其进行了相应表征;利用撞击和摩擦感度试验、慢烤试验及DSC测试分别研究了不同粒度、形貌及粒度分布的RDX样品的安全性能和热分解特性。研究结果表明,粒度、形貌及粒度分布是影响RDX安全和热分解性能的重要因素。随着粒度的减小,RDX的机械和热感度显著降低。另外,窄粒度分布的RDX样品普遍具有更低的机械感度,而宽粒度分布的RDX样品通常具有更好的热稳定性。     

基于两类风险的正态分布Bayes试验样本量

对在方差已知正态分布情形下的装备Bayes试验设计方案进行了研究.给出了在两类风险要求下验证试验方案的求解思路、简单假设下试验验证方案的求解过程、试验样本量的计算公式.结合实例对试验设计方案求解的过程进行了分析,通过与经典方法的对比验证了方法的有效性.     

Influence of aircraft surface distribution on electromagnetic scattering characteristics

In this paper, two typical stealth aircraft concepts (wing fuselage blended and flying-wing) were designed. Then three gradually changed surface distribution models with the same plan-form for each concept were created. Based on the multilevel fast multipole algorithm (MLFMA), the vertical polarization transmitting/vertical polarization receiving (VV) and horizontal polariza-tion transmitting/horizontal polarization receiving (HH) radar cross section (RCS) characteristics were simulated with five frequencies between 0.1 and 1.0 GHz. The influences and mechanisms of aircraft surface distribution on electromagnetic scattering characteristics were investigated. The results show that for the wing fuselage blended concept, the VV RCS of this frequency range is higher than the HH RCS in most cases, while it is just the opposite for the flying-wing concept. As for the two aircraft concepts, the RCS levels of HH and VV both decrease with the frequency increasing, but the HH RCS has a faster downward trend. The surface distribution has little influ-ence on HH RCS characteristics. On the contrary, it has a significant impact on VV RCS charac-teristics, and the amplitude of the VV RCS increases with the surface thickness.     

无壳装药接触爆炸冲量计算的几何分析法

通过几何分析方法得出无壳装药接触爆炸冲量的计算公式并和已有的计算公式进行了对比,指出现行计算公式存在的缺陷。通过瞬态爆轰假设,从理论上分析了现有公式的正确性。实验结果表明:采用几何分析的方法得出的计算公式能较好地符合实际。     

基于两类指数不完全数据的最优等间距设计

对来自指数分布总体的类不完全样本：分组样本与一次性样本，当观察时间为等长时，本文研究了最优时间区间长度问题。这种研究是基于渐近方差达到最小的原则。     

气体静压向心轴承静态特性的理论分析

本文根据简化的二维流动模型,提出一种新的计算方法,用以计算小孔节流气体静压向心轴承的承载能力和刚度。该计算方法简单方便,理论计算结果与实验结果很接近,适合于工程上的实际应用。     

指数分布情形下恒定应力加速试验的最优设计

本文主要讨论了指数分布情形下,均值对数与加速应力满足通常的Arrhenius模型或逆幂律情形时,恒定应力加速试验在定数截尾和定时截尾二种情形下试验的最优设计。     

The massive star distribution in the Galaxy and the Magellanic Clouds

The numbers and distribution of Population I O-type stars and Wolf-Rayet stars are reviewed. The numbers of known WR stars in the Galaxy, the LMC and the SMC are 185, 114, and 9, respectively. Distances and galactic distributions determined by various authors are compared. The single star and binary distributions are discussed in the light of evolutionary studies.     

The management of stray radiation issues in space optical systems

The performance of infrared and submillimeter systems can be severely degraded by stray light. Stray light includes off-axis radiation, system diffraction and scattering effects, and thermal self-emission. The purpose of this paper is to identify several keys to preventing system degradation due to stray radiation. The first key is to apply stray light design rules and analysis techniques early in the program before the design is finalized. A systems level analysis using stray light analysis software is often necessary in order to identify more subtle problems and to assess the magnitude of their effect on system performance. Another key is to address contamination control and the choice of surface coatings early in the program. The management of stray radiation issues is extremely cost-effective, if begun early in the program, and can reduce later schedule hardships.     

软件可靠性定量指标的分配与验证

阐述了软件开发过程中可靠性定量指标的分配原则和方法 ,对定量指标的验证进行了分析和探讨 ,研究了基于不同模型的验证方法 ,最后给出了一个控制软件可靠性分配和验证的例子。