铁基非晶纳米晶涂层的耐磨性研究

采用基于机器人的自动化高速电弧喷涂技术在45钢基体上制备了FeCrBSiMnNbY非晶纳米晶涂层。研究了非晶纳米晶涂层在油润滑条件下,不同磨损时间、速度、载荷对涂层的磨损行为。采用扫描电镜（SEM）、能谱分析仪（EDAX）和X射线衍射仪（XRD）对涂层的组织结构进行了表征,利用纳米压痕仪对涂层的力学性能进行了分析,摩擦磨损试验在MM200滑块磨损试验机上进行。结果表明：涂层组织均匀,结构致密,主要由非晶相和α-Fe相纳米晶组成;在相同磨损试验条件下,非晶纳米晶涂层的相对耐磨性为3Cr13涂层的4．6倍,磨损机制主要为脆性疲劳剥落。     

基于支持向量机的威胁判断模型

目标威胁判断是防空作战中一项重要内容,在建立目标威胁模型时,首先要挑选特征参数,分析了影响威胁度的若干因素.这里采用Rough理论中知识约简方法选择目标的特征参数;支持向量机是一类新型机器学习方法,由于其出色的学习能力,该技术已成为当前国际机器学习界的研究热点,利用支持向量机建立了威胁判断模型,给出了实例和解决此问题的支持向量机源程序.通过实例与神经网络法的结果进行了比较,结果表明支持向量机比较精确和简单.     

Performance study of jute-epoxy composites/sandwiches under normal ballistic impact

This study is undertaken to explore the use of natural fiber Jute-epoxy (JE), Jute-epoxy-rubber (JRE) sandwich composite for ballistic energy absorption. Energy absorbed and residual velocities for these composites are evaluated analytically and through Finite Element Analysis (FEA). FE analysis of JE plates is carried out for different thicknesses (3, 5, 10 and 15 mm). JE plates and JRE sandwiches having the same thickness (15 mm) are fabricated and tested to measure residual velocity and energy absorbed. The analytical results are found to agree well with the results of FE analysis with a maximum error of 9%. The study on JE composite plate reveals that thickness influences the energy absorption. Experimental and FE analysis study showed that JRE sandwiches have better energy absorption than JE plates. Energy absorption of a JRE sandwich is about 71% greater than JE plates. Damages obtained from FEA and testing are in good agreement. SEM analysis confirms composites failed by fiber rupture and fragmentation.     

GSVM:一种支持Gather/Scatter的向量存储器

宽单指令多数据流(Single Instruction Multiple Data, SIMD)架构数字信号处理器一般都能高效支持地址连续或等距跨步等规则应用的向量访存,但对于科学与工程计算中广泛存在的不规则应用的数据访存则带宽利用率往往较低,从而大幅降低了其整体运算能效。为了提高不规则应用的向量访存性能,基于某SIMD数字信号处理器的体系结构,设计了一种支持Gather/Scatter访存的向量存储器GSVM。通过设计与SIMD宽度相匹配的向量地址计算单元和合适深度的冲突缓冲器阵列,实现了Gather/Scatter指令向量地址计算、仲裁与缓存的全流水访存操作。实验结果表明,相比以前不支持Gather/Scatter访存的存储器,GSVM在增加22%的硬件代价基础上,基于稀疏矩阵向量乘的测试程序集获得了2～8的性能加速比。     

空间矢量脉宽调制的研究

对空间矢量脉宽调制(SVPWM)的理论进行了较详细的讨论.利用DSP电机控制器TMS320F240实现SVPWM,分析了该方法的特点,并给出了相应的实验结果.     

双机空战模拟结果评判研究

定义了空战模拟结果指标-空战结果矢量和取胜矢量,推导了基于武器杀伤概率的取胜矢量计算方法,为定量研究作战飞机空战效能提供了依据。     

平视显示器教学模拟器改进设计研究

用80C196单片机作为显示处理机构成一块基于AT总线的插卡,用以取代原平视显示器教学模拟器显控计算机和矢量产生器插件板,使系统结构简化、成本降低,并提高系统可靠性。部分设计实例已应用在某型飞机模型器火控系统部件、某型平视显示器电子部件改进设计中。     

时间跨度对GPS坐标序列噪声模型及速度估计影响分析

选取全球范围内72个基准站的坐标序列,采用改进的赤池信息量准则、贝叶斯信息量准则对不同噪声模型组合进行噪声分析,得到基准站坐标序列的最优噪声模型及速度参数,探讨时间序列跨度对噪声模型及速度估计的影响。结果表明,基准站坐标序列噪声模型不能由单一的噪声模型表述,其呈现出多样性特征,主要表现为幂律噪声、高斯马尔科夫噪声、闪烁噪声+白噪声特征,且三坐标分量表现出不同的噪声特性;随着时间跨度的增加,坐标时间序列的最优噪声模型、GPS站速度及其不确定度逐渐由发散趋于收敛,随机游走噪声模型的比重有所增加。结果表明10 a以上的时间跨度是较为理想的噪声模型估计尺度。     

基于高阶滑模微分器的增广比例导引律

导引律的设计在导弹制导与控制中具有重要作用,为了解决增广比例导引中导弹-目标视线角速度和视线角加速度不易获得的问题,设计了一种基于高阶滑模微分器的增广比例导引律。首先,根据高阶滑模微分器的数学模型建立视线角速度和视线角加速度的估计模型;其次,根据视线角速度和视线角加速度的估计值,利用一种光滑无抖阵滑模微分器构造增广比例导引律。最后,通过仿真验证表明,具有滑模微分器结构的增广比例导引律导引性能良好。     

Defense–Growth Causality: Considerations of Regime-Switching and Time- and Country-Varying Effects

This paper develops a panel smooth transition vector autoregressive model to investigate the economic growth–defense causality. This model simultaneously resolves the estimation problems of endogeneity, heterogeneity, and nonlinearity. Empirical results support that the causality is bidirectional, nonlinear, time- and country-varying. Economic growth has a negative impact on military spending and vice versa. The larger the HDI, the smaller the negative causality. Evidently, the increase in the level of country development can reduce the negative impact of military outlays on economic growth. Reducing the ratio of military spending to GDP is beneficial for countries with low HDI scores; however, moderately increasing the share of military expenditure is favorable for countries with extremely high HDI scores. Policy authority needs to set optimal education, health, and economic development shares of GDP for purchasing a maximum economic growth rate.