Experimental investigation on anti-penetration performance of polyurea-coated ASTM1045 steel plate subjected to projectile impact

In this study, the anti-penetration performance of polyurea/ASTM1405-steel composite plate subjected to high velocity projectile was analyzed. Two kinds of modified polyurea material (AMMT-053 and AMMT-055) were selected and a ballistic impact testing system including speed measuring target system and high-speed camera was designed. This experiment was conducted with a rifle and 5.8 mm projectile to explore the effects by the polyurea coating thickness, the polyurea coating position and the glass-fiber cloth on the anti-penetration performance of polyurea/ASTM1405-steel composite plate. The result showed that the effects of polyurea coating position were different between two types of polyurea, and that the effects of glass-fiber position were disparate between two types of polyurea as well. For AMMT-053 polyurea material, it was better to be on front face than on rear face; whereas for AMMT-055 pol-yurea, it was better to be on rear surface although the difference was very subtle. Additionally, formulas had been given to describe the relationship between the effectiveness of polyurea and the thickness of polyurea coating. In general, AMMT-055 had better anti-penetration performance than AMMT-053. Furthermore, five typical damage modes including self-healing, crack, local bulge, spallation and local fragmentation were defined and the failure mechanism was analyzed with the results of SHPB test. Additionally, the bonding strength played an important role in the anti-penetration performance of polyurea/steel composite plate.     

掠海地效翼船——21世纪的新型海上高速运输运载工具

介绍了一种新型海上高速运载工具——地效翼船的过去和现状,特别是其在俄罗斯的发展.分析了地效翼船的性能及技术特点,并讨论了它的商业用途和军事用途.     

基于自由边控制流图的路径覆盖分析实现方法

针对路径覆盖测试,给出了一般循环结构的一种简化处理方案及把按此方案得到的控制流图转化为自由边控制流图方法,并探讨了基于自由边控制流图进行路径覆盖分析的实现方法和优点。     

超声波频率与功率对三合二洗消液抗冻性能影响的研究

针对严寒条件下三合二洗消液防冻结问题,研究采用向消毒液中释放大功率超声波的方法,较好地解决了三合二消毒液在低温时出现沉淀、冻结的问题．     

某型子母弹子弹稳定带参数筛选技术分析

本文以某型子母弹子弹研制过程中遇到的问题为背景,分析了子母弹子弹稳定带对子弹落姿和可靠性影响,通过机理分析和试验验证得出了稳定带参数优化调整方案,对相关产品优化设计及技术改进有一定借鉴意义。     

q∝△(T~(-1))传热时三热源热泵的最优性能普遍关系

本文导出工质与三个热源间的传热系数分别为。α、β和γ,传热规律为q~∝△(T~(-1))时,内可逆三热源热泵的最佳供热系数ψ与供热率Π间的关系:ψ<1时,Π=K_1ψ[T_p(T_H-T_ο)-T_H(T_p-Tο)ψ]/[T_HT_pT_ο(1-△_1ψ)~2];ψ>1时,Π=K_2ψ[T_p(T_H-T_ο)-T_H(T_P-T_ο)ψ]/[T_HT_pT_ο(△_2-ψ)~2];式中,K_1=αγ/(α~(1/2)+γ~(1/2))~2,K_2=βγ/(β~(1/2)+γ~(1/2))~2,△_1=(α/β)~(1/2)(β~(1/2)-r~(1/2)/(α~(1/2)+γ~(1/2)),△_2=(β/α)~(1/2)(α~(1/2)-γ~(1/2))/(β~(1/2)+γ~(1/2))。由此可得许多有用的关系。     

Economic screening procedures in logistic and normal models

Economic screening procedures based on a continuous screening variable X in place of a dichotomous performance variable T are presented. Optimal critical values on the screening variable minimizing the expected cost are obtained for two models; it is assumed that X given T is normally distributed in normal model and P[T = 1|X] is a logistic function of X in the logistic model, and that costs are incurred by screening inspection and misclassification errors. Cases where some parameters are unknown are also considered.     

传热规律对卡诺热泵有限时间(火用)经济最优性能的影响

本文导出了一种较为普遍的传热规律 q∝△(T~n)时内可逆卡诺热泵的最佳供热系数、利润率关系,并藉此讨论了几种传热规律时内可逆卡诺热泵的有限时间(火用)经济最优性能,得到了一些新的普适结果。     

关于有限时间热力学的最小熵产生最大值原则

本文力图从能表征状态的热力学参数熵的变化中找到有关有限时间热力学新的分析方法,提出了工作参数选择的最小熵产生最大值原则。这个原则揭示了有限时间热力学以时间为基础的“率”与非平衡热力学熵产生间的内在联系。据此,我们便可得到正、反向内可逆卡诺循环的最佳工作参数。为有限时间热力学的普遍应用研究提供了一新的线索。     

Fulfillment by Amazon versus fulfillment by seller: An interpretable risk-adjusted fulfillment model

With dual-channel choices, E-retailers fulfill their demands by either the inventory stored in third-party distribution centers, or by in-house inventory. In this article, using data from a wedding gown E-retailer in China, we analyze the differences between two fulfillment choices—fulfillment by Amazon (FBA) and fulfillment by seller (FBS). In particular, we want to understand the impact of FBA that will bring to sales and profit, compared to FBS, and how the impact is related to product features such as sizes and colors. We develop a risk-adjusted fulfillment model to address this problem, where the E-retailer's risk attitude to FBA is incorporated. We denote the profit gaps between FBA and FBS as the rewards for this E-retailer fulfilling products using FBA, our goal is to maximize the E-retailer's total rewards using predictive analytics. We adopt the generalized linear model to predict the expected rewards, while controlling for the variability of the reward distribution. We apply our model on a set of real data, and develop an explicit decision rule that can be easily implemented in practice. The numerical experiments show that our interpretable decision rule can improve the E-retailer's total rewards by more than 35%.