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排序方式: 共有253条查询结果,搜索用时 750 毫秒
91.
Qiang Liu Peng-wan Chen Yan-song Guo Jian-jun Su Lu Han Ali Arab Jian-fei Yuan 《防务技术》2021,17(2):495-504
Polyurea is an elastomeric material that can be applied to enhance the protection ability of structures under blast and impact loading.In order to study the compressive mechanical properties of SiC/polyurea nanocomposites under quasi-static and dynamic loading,a universal testing machine and split Hop-kinson pressure bar(SHPB)apparatus were used respectively.The stress-strain curves were obtained on polyurea and its composites at strain rates of 0.001-8000 s-1.The results of the experiment suggested that increase in the strain rates led to the rise of the flow stress,compressive strength,strain rate sensitivity and strain energy.This indicates that all of the presented materials were dependent on strain rate.Moreover,these mechanical characters were enhanced by incorporating a small amount of SiC into polyurea matrix.The relation between yield stress and strain rates were established using the power law functions.Finally,in order to investigate the fracture surfaces and inside information of failed specimens,scanning electron microscopy(SEM)and micro X-ray computed tomography(micro-CT)were used respectively.Multiple voids,crazes,micro-cracks and cracking were observed in fracture surfaces.On the other hand,the cracking propagation was found in the micro-CT slice images.It is essential to understand the deformation and failure mechanisms in all the polyurea materials. 相似文献
92.
郭守苓 《军队政工理论研究》2005,6(4):27-28
提高党委班子领导能力,必须把“两个武装”摆在首位,认真贯彻民主集中制原则,振奋精神状态,保持旺盛斗志,树立和落实科学的指导观,把握部队建设规律,提高领导工作效能,塑造良好整体形象。 相似文献
93.
Takai试剂(CH2I2-Zn-TiCl4)作为亚甲基化试剂能高效地使羰基亚甲基化,这一方法与运用Wittig试剂等方法相比,反应条件更加温和、副产物更少、合成成本较低且收率高。 相似文献
94.
We consider two game‐theoretic settings to determine the optimal values of an issuer's interchange fee rate, an acquirer's merchant discount rate, and a merchant's retail price in a credit card network. In the first setting, we investigate a two‐stage game problem in which the issuer and the acquirer first negotiate the interchange fee rate, and the acquirer and the retailer then determine their merchant discount rate and retail price, respectively. In the second setting, motivated by the recent US bill “H.R. 2695,” we develop a three‐player cooperative game in which the issuer, the acquirer, and the merchant form a grand coalition and bargain over the interchange fee rate and the merchant discount rate. Following the cooperative game, the retailer makes its retail pricing decision. We derive both the Shapley value‐ and the nucleolus‐characterized, and globally‐optimal unique rates for the grand coalition. Comparing the two game settings, we find that the participation of the merchant in the negotiation process can result in the reduction of both rates. Moreover, the stability of the grand coalition in the cooperative game setting may require that the merchant should delegate the credit card business only to the issuer and the acquirer with sufficiently low operation costs. We also show that the grand coalition is more likely to be stable and the U.S. bill “H.R. 2695” is thus more effective, if the degree of division of labor in the credit card network is higher as the merchant, acquirer, and issuer are more specialized in the retailing, acquiring, and issuing operations, respectively. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012 相似文献
95.
随着并行计算的成熟,众多数据密集型的栅格处理算法亟需利用并行计算来缩减执行时间.针对其中一类邻域型算法,构建了用于估计是时间代价的串行/并行时域模型,分析了各个组成的代价影响因素,提出了降低数据I/O代价的并行I/O方法和降低数据通信代价的光圈预测方法.实验证明,所提的两个优化方法可以使邻域型栅格处理算法的并行程序更加充分地利用并行计算资源,进而在一般并行化的基础上进一步提升其并行性能. 相似文献
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99.
喷气燃料中硫化物对银片腐蚀的量化表征 总被引:1,自引:1,他引:0
银片腐蚀主要受喷气燃料中硫化物的影响,不同种类、结构的硫化物对银片腐蚀的影响不同,从喷气燃料中硫化物系统角度来研究对银片腐蚀影响是很有意义的。采用量化自组织神经网络从定性、定量两个方面研究喷气燃料中硫化物对银片腐蚀的影响,研究结果表明,能够从喷气燃料硫化物的存在情况来预测银片腐蚀结果。 相似文献
100.
从目标探测设备、车辆综合电子设备、战场战斗识别系统和导航定位技术四个方面 ,阐述了坦克火控系统中采用的先进数字化技术和设备 ,并简述了将坦克纳入 C3I系统中时所使用的先进的通信系统。 相似文献