半自动输弹机模糊控制系统

针对某半自动输弹机系统实际的输弹过程,提出了模糊控制系统的控制方案,根据本输弹机系统的模型设计了模糊控制参数。运用Matlab/Simulink仿真软件分别对采用模糊控制的系统和采用普通PID控制算法的系统进行仿真,得到各系统的单位阶跃响应曲线图和抗干扰信号图。对输弹机进行上炮试验,对比采用模糊控制的系统和采用普通PID控制算法的系统的实验结果,得到采用模糊算法的输弹机系统的卡膛一致性能很好的满足要求,具有一定的实践意义。     

Burning characteristics of high density foamed GAP/CL-20 propellants

The monolithic foamed propellants with high densities were prepared by casting and two-step foaming processes. Glycidyl azide polymer (GAP) and isocyanate were used as the binder system and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW, CL-20) was employed as the energetic component. The newly designed formulation containing 60 % CL-20 produced a force constant of 1077 J/g and low flame temperature of 2817 K. Two foamed propellants with densities of 1.32 g/cm³ and 1.53 g/cm³ were fabricated by a confined foaming process and examined by closed bomb tests. The results revealed that porosity significantly affects burning performance. A size effect on combustion behaviors was observed for the foamed propellant with 5.56 % porosity, and a double-hump progressive dynamic vivacity curve was obtained. At last, the 30 mm gun test was carried out to demonstrate the interior ballistic performance, and the muzzle velocity increased by 120 m/s at the same maximum chamber pressure when monolithic propellant was added in the charge.     

基于BP人工神经网络的GPS/SINS组合导航算法

基于扩展Kalman滤波的GPS/SINS组合导航算法,需要对原始的非线性连续系统模型进行线性化和离散化处理,要求系统噪声和测量噪声为零均值的高斯白噪声,且易于出现滤波器发散。BP人工神经网络无需对所求解的问题建模,能够很好地逼近系统非线性特性,获得较高精度的导航定位信息;还具有计算过程稳定,不涉及矩阵求逆,不需要迭代逼近,以及容易实现并行处理等优点。设计适用于GPS/SINS组合导航系统的BP网络模型,并在标准的BP算法基础上,采用共轭梯度法改进网络训练速度及精度。最后,通过仿真算例说明BP网络方法用于GPS/SINS组合导航计算的可行性。     

ZCS半桥式DC/DC变流器状态空间法建模及Matlab仿真分析

分析了一种ZCS半桥式DC DC变流器时域工作特性.通过研究其工作各阶段的特性建立了其状态空间模型,采用Matlab语言进行编程仿真,得到其输出电压时域仿真波,与实测吻合,证明了所建状态空间模型的正确性,得到变流器工作的一些有用结论,有助于指导下一步变流器的传导干扰分析和抑制.     

AMESim与MATLAB/Simulink联合仿真技术及应用

分析了AMESim与MATLAB/Simulink的特点,对两者的联合仿真技术进行了研究,解决了联合仿真的接口问题.并把该技术应用于主动悬架系统,取得了良好效果.     

WSEIAC模型的中远程空空导弹武器系统效能分析

依据中远程空空导弹武器平台系统的战术指标,建立了中远程空空导弹武器平台系统的效能评价体系.对ADC扩展模型中的人为因素K进行了修正,在能力矩阵C中增加对载机生存能力和信息支持能力的体现.在此基础上给出了修正扩展模型下的系统效能,计算了在原始ADC模型下的系统效能,并对两种模型下的效能差异进行了比较.     

军用飞机综合效能/费用评估方法

军用飞机的效能与费用是两个相互制约的因素,对两者进行科学合理的综合评估,对于军用飞机的发展和使用有着很重要的意义。在分析综合效能/费用的基本评估指标基础上,提出了在军用飞机全寿命周期综合效能/费用评估指标,重点对作战使用阶段的最佳效能/费用进行评估分析,最后给出结论。     

The effect of al particle size on thermal decomposition,mechanical strength and sensitivity of Al/ZrH2/PTFE composite

To study the thermal decomposition of Al/ZrH2/PTFE with different Al particle size as well as mechanical strength and impact sensitivity under medium and low strain rates, molding-vacuum sintering was adopted to prepare four groups of power materials and cylindrical specimens with different Al particle size. The active decomposition temperature of ZrH2 was obtained by TG-DSC, and the quasi-static me-chanics/reaction characteristics as well as the impact sensitivity of the specimen were studied respec-tively by quasi-static compression and drop-hammer test. The results show that the yield strength of the material decreased with the increase of the Al particle size, while the compressive strength, failure strain and toughness increased first and then decreased, which reached the maximum values of 116.61 MPa, 191％, and 119.9 MJ/m respectively when the Al particle size is 12—14μm because of particle size grading. The specimens with the highest strength and toughness formed circumferential open cracks and reacted partly when pressed. Those with developmental cracks formed inside did not react. It is considered that fracture of specimens first triggered initial reaction between Al and PTFE to release an amount of heat. Then ZrH2 was activated and decomposed, and participated in subsequent reaction to generate ZrC. The impact sensitivity of the specimens decreased with the increase of Al particle size.     

Micromechanical simulation and experimental investigation of aluminum-based nanocomposites

Ceramic reinforced metal matrix nanocomposites are widely used in aerospace and auto industries due to their enhanced mechanical and physical properties. In this research, we investigate the mechanical properties of aluminum/Nano-silica composites through experiments and simulations. Aluminum/Nano-silica composite samples with different weight percentages of silica nanoparticles are prepared via powder metallurgy. In this method, Nano-silica and aluminum powders are mixed and compressed in a mold, followed by sintering at high temperatures. Uniaxial tensile testing of the nanocomposite samples shows that adding one percent of Nano-silica causes a considerable increase in mechanical properties of nanocomposite compared to pure aluminum. A computational micromechanical model, based on a representative volume element of aluminum/silica nanocomposite, is developed in a commercial finite element software. The model employs an elastoplastic material model along with a ductile damage model for aluminum matrix and linear elastic model for nano-silica particles. Via careful determination of model parameters from the experimental results of pure aluminum samples prepared by powder metallurgy, the proposed computational model has shown satisfactory agreement with experiments. The validated computational model can be used to perform a parametric study to optimize the micro-structure of nanocomposite for enhanced mechanical properties.     

Effect of functionally-graded interphase on the elasto-plastic behavior of nylon-6/clay nanocomposites; a numerical study

In nanocomposites, the interphase thickness may be comparable to the size of nano-particles, and hence, the effect of interphase layers on the mechanical properties of nanocomposites may be substantial. The interphase thickness to the nano-particle size ratio and properties variability across the interphase thickness are the most important affecting parameters on the overall behavior of nanocomposites. In this study, the effect of properties variability across the interphase thickness on the overall elastic and elasto-plastic properties of a polymeric clay nanocomposite (PCN) using a functionally graded (FG) interphase is investigated in detail. The results of the computational homogenization on the mesoscopic level show that Young's modulus variation of the interphase has a significant effect on the overall elastic response of nanocomposites in a higher clay weight ratio (Wt). Moreover, strength variation through the interphase has a notable effect on the elasto-plastic properties of PCNs. Also, the increase or decrease in stiffness of interphase from clay to matrix and vice versa have a similar effect in the overall behavior of nanocomposites.