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71.
The Cr-plated coating inside a gun barrel can effectively improve the barrel's erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gun-powder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel's inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface's ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel. 相似文献
72.
基于RTP协议H.264视频流传输QoS保证的研究 总被引:2,自引:0,他引:2
提出一个Linux环境下基于RTP/RTCP的H.264视频流传输的方案,在Linux中调用V4L(VideofourLinux)的API函数采集视频流,经X264压缩,RTP/RTCP协议打包进行传输。并通过RTCP的RR(接收方报告)包反馈信息和吞吐量公式来计算近似带宽,以起始帧量化参数start-qp为视频编码的调节参数,由近似带宽来控制视频编码的参数调整,达到控制输出码率的目的,实现对视频传输的QoS(QualityofService)保证。 相似文献
73.
三坐标雷达目标真实高度估计算法研究 总被引:1,自引:0,他引:1
在目标跟踪领域,通过三坐标雷达的测量值(斜距、仰角及方位角)来估算目标的真实高度一直是个难点。目前主要有两类处理方法:坐标转换法和等效地球半径法。前者把与雷达天线相关的三坐标测量值转换到大地坐标系统来计算目标高度;后者充分考虑地球曲率以及大气折射的特性,通过增加地球半径来估算目标的高度。最后对上述的两类方法进行总结、比较与分析。 相似文献
74.
75.
以二维碳纤维布和廉价的聚硅氧烷为原料,采用先驱体转化工艺制备2D Cf/Si-O-C材料,对其力学性能进行了考察,并与以聚碳硅烷为先驱体制备的2D Cf/SiC材料在价格和性能方面进行了对比。实验表明,2D Cf/Si-O-C材料力学性能较2D Cf/SiC材料有所下降,但成本大大降低。2D Cf/Si-O-C材料弯曲强度达到157.9 MPa,断裂韧性达到8.4MPa.m1/2,剪切强度达到23.4MPa,并且在1400℃下能较好保持材料的力学性能。 相似文献
76.
While there has been significant previous literature on inventory transshipment, most research has focused on the dealers' demand filling decision (when to fill transshipment requests from other dealers), ignoring the requesting decision (when to send transshipment requests to other dealers). In this paper we develop optimal inventory transshipment policies that incorporate both types of decisions. We consider a decentralized system in which the dealers are independent of the manufacturer and of each other. We first study a network consisting of a very large number of dealers. We prove that the optimal inventory and transshipment decisions for an individual dealer are controlled by threshold rationing and requesting levels. Then, in order to study the impact of transshipment among independent dealers in a smaller dealer network, we consider a decentralized two‐dealer network and use a game theoretic approach to characterize the equilibrium inventory strategies of the individual dealers. An extensive numerical study highlights the impact of the requesting decision on the dealers' equilibrium behavior in a decentralized setting. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献
77.
Jacques Fontanel 《Defence and Peace Economics》2013,24(2):135-147
The evolutions of military expenditures in Eastern and Central European countries are difficult to estimate and to compare, due to the lack of available data for these states. Some results of the extent of cuts in defence spending since 1990 are interesting to interpret, but it is difficult for econometricians to use these figures even carefully. The structures of national military expenditure have been modified to the detriment of arms equipment. Thus, the disarmament process needs a special analysis of the arms industry. 相似文献
78.
Martin C. Mcguire 《Defence and Peace Economics》2013,24(4):251-270
A nation's wealth is both an object of conquest to covetous aggressors and a resource to its owners for self defense. To maintain autonomy every country must mount a defense which either makes its capture (1) more expensive than any aggressor can afford, or (2) more expensive than it is worth to aggressors. Whether this condition can be satisfied for all countries simultaneously depends as shown in this paper on relative efficacy of military offense versus defense, the aggregate of wealth among nations and its distribution, and the benefits a conqueror may obtain from conquest, including the duration of these benefits. The paper shows how these factors fit together to determine the sustainability and stability of the international distribution of property as embodied in the configuration of sovereign states. 相似文献
79.
80.
设计了新型半圆管形式的不锈钢板式换热器,对其作为太阳能光电热综合利用一体化系统集热组件的性能进行实验研究。通过新型集热光电热组件及光电组件系统的对比实验,研究该光电热组件在重庆地区夏季应用情况,分析其光电和光热特性。结果表明:在以晴朗为主的天气,半圆管形式的不锈钢板式光电热组件电热系统的电热性能与光电组件系统的相比较,前者的太阳能电池输出功率提高约26.48%,热利用效率提高23.70%以上,新型半圆管形式的光电热组件整体光电热(光电+光热)综合效率可达到25.70%,有效提高了光电热系统的综合效率。新型半圆管形式不锈钢板式换热器的换热面积增大,提高了换热效率,为太阳能光电热综合利用一体化系统在重庆等太阳辐射强度较小地区的应用提供了参考。 相似文献