Using container inspection history to improve interdiction logistics for illicit nuclear materials

Strengthening the United States' ability to prevent adversaries from smuggling nuclear materials into the country is a vital and ongoing issue. The prospect of additional countries, such as Iran, obtaining the know‐how and equipment to produce these special nuclear materials in the near future underscores the need for efficient and effective inspection policies at ports and border crossings. In addition, the reduction of defense and homeland security budgets in recent years has made it increasingly important to accomplish the interdiction mission with fewer funds. Addressing these complications, in this article, we present a novel two‐port interdiction model. We propose using prior inspection data as a low‐cost way of increasing overall interdiction performance. We provide insights into two primary questions: first, how should a decision maker at a domestic port use detection data from the foreign port to improve the overall detection capability? Second, what are potential limitations to the usefulness of prior inspection data—is it possible that using prior data actually harms decision making at the domestic port? We find that a boundary curve policy (BCP) that takes into account both foreign and domestic inspection data can provide a significant improvement in detection probability. This BCP also proves to be surprisingly robust, even if adversaries are able to infiltrate shipments during transit. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 433‐448, 2013     

NICALON SiC/Al 预制丝热膨胀特性研究

本文研究了NICALON SiC束丝纤维增强铝预制丝在15～400℃温度区间内的热膨胀特性。研究表明预制丝两次热循环后得到的膨胀曲线不一致,该曲线在15～400℃范围的平均热膨胀系数分别为3.2×10~(-6)℃~(-1)、4.1×10~(-6)℃~(-1)。本文对预制丝的热膨胀行为进行了理论分析和探讨,计算值和实验值较为符合。     

基于模糊Petri网的航材供应链冲突诊断建模与分析

结合航材供应链特点,建立航材供应链冲突诊断指标体系,并将节点问协作指标引入体系之中。通过模糊产生式规则,建立航材供应链冲突诊断模型,进行诊断推理,找出引起冲突的关键因素,并提出航材供应链冲突的防范对策。     

共晶复合陶瓷损伤过程的有限元分析

针对共晶复合陶瓷的微观结构特征,建立了含强约束界面相的有限元模型,模拟了包含片状夹杂共晶复合陶瓷材料的外载应力场分布规律;应用ANSYS的APDL语言进行编程,对材料的损伤过程进行了研究。结果表明材料的破裂由基体损伤决定,随着外载荷的增加,损伤破坏沿界面延伸,并逐渐向基体内部扩展,最终造成基体的断裂。     

超音速气流中热塑性复合材料壁板的非线性热颤振特性

热塑性复合材料结构在高速流场中的颤振行为是可重复使用航天器设计中需要考虑的问题.基于Mindlin厚板理论和Von-Karman大变形理论描述热塑性复合壁板结构大变形,超音速气动力采用活塞气动理论.考虑温度引起的壁板面内热应力和热塑性材料力学性能的改变.根据虚功原理和有限元法推导建立了热塑性复合材料壁板的热颤振模型,进...     

Experimental and numerical study of the blast wave decrease using sandwich panel by granular materials core

Among the intrinsic properties of some materials, e.g., foams, porous materials, and granular materials, are their ability to mitigate shock waves. This paper investigated shock wave mitigation by a sandwich panel with a granular core. Numerical simulations and experimental tests were performed using Autodyn hydro-code software and a shock tube, respectively. The smoothed particle hydrodynamics (SPH) method was used to model granular materials. Sawdust and pumice, whose properties were determined by several compression tests, were used as granular materials in the sandwich panel core. These granular materials possess many mechanisms, including compacting (e.g., sawdust) and crushing (e.g., pumice) that mitigate shock/blast wave. The results indicated the ineffectiveness of using a core with low thickness, yet it was demonstrated to be effective with high thickness. Low-thickness pumice yielded better results for wave mitigation. The use of these materials with a core with appropriate core reduces up to 88% of the shock wave. The results of the experiments and numerical simulations were compared, suggesting a good agreement between the two. This indicates the accuracy of simulation and the ability of the SPH method to modeling granular material under shock loading. The effects of grain size and the coefficient of friction between grains have also been investigated using simulation, implying that increasing the grain size and coefficient of friction between grains both reduce overpressure.     

自润滑弹带挤进过程中渗出油量的对比计算

从弹带的作用及特性出发, 通过数值计算和统计计算 2种方法计算了自润滑弹带挤进过程中的渗出油量,初步得出了渗出油量和行程之间的关系。这一问题的解决为自润滑弹带材料的选择提供了理论依据。通过对 2种算法的比较可知, 数值计算误差更小一些, 而统计计算对数学条件要求不太苛刻。     

弹道冲击下层合板破坏模式及抗弹性能实验研究

以舰用轻型复合装甲研究为背景,针对不同纤维增强种类(包括玻纤织物 C400、C200、SW220 和芳纶纤维织物T750)以及不同面密度层合板结构,在6.2 g刚性微曲面柱形弹弹道冲击下的防护能力展开实验研究,着重讨论了层合板结构弹道冲击下破坏模式、弹体初始侵彻速度及面密度与抗弹能力和抗弹效率之间的关系,认为不同的破坏模式体现了不同的吸能特性和纤维失效机理.     

通用雷达装备维修器材储供标准模型

研究了通用雷达装备零部件寿命分布类型,给出了以可靠性为依据确定维修器材储供数量和排序参数的计算公式,分析了器材最小包装对计算结果和维修器材排序参数的影响,以及器材关键性对排序的影响及评判方法。     

活塞环表面CrTiAlN复合涂层的抗高温腐蚀性能研究

采用多弧离子镀技术,利用Cr靶和TiAl靶,在活塞环材料65 Mn钢基体上制备了CrTiAlN复合涂层,并对电镀Cr、CrN和CrTiAlN复合涂层在800℃下的抗高温腐蚀性能进行了比较分析,用扫描电镜、能谱仪和X射线衍射仪观察分析了样品表面高温腐蚀氧化膜。结果表明:CrTiAlN复合涂层具有优异的抗高温腐蚀性能,在800℃时仍具有良好的抗高温腐蚀性能,其氧化机理是O向涂层内部扩散氧化,在高温腐蚀过程中,CrTiAlN涂层中的Cr发生了选择性氧化,优先形成了Cr2O3,CrTiAlN涂层氧化层区域的结构由外至里组成顺序为Cr2O3、Al2O3+TiO2、(Cr,Ti,Al)N。涂层外层的Cr2O3氧化物有利于阻碍氧元素向涂层内部扩散,能够降低涂层的高温腐蚀速度。