基于模糊神经网络的武器控制系统信号分析

某新型飞机武器控制系统故障诊断过程复杂,故障征兆和故障原因之间存在着许多不确定因素,精确定位故障存在许多困难.针对这种情况,提出了基于模糊神经网络,研究了模糊神经网络技术在武器控制系统故障诊断领域的应用,并根据系统本身的特点,提出了诊断和算法模型.在此基础上,研制出武器控制系统检查仪,对该方法作了验证.结果表明:该方法是可行和有效的.     

应用统计能量分析法预测板材隔声量

应用统计能量分析法SEA(Statistical Energy Analysis)预测板隔声量,先建立板材的SEA模型,将板材的隔声量预测转变成求解声振动功率的线性代数方程组,对方程组的变量(SEA参数)值进行确定,得出板材的隔声量,再根据混响室法测量板材实际隔声量。将预测结果与实验结果进行对比分析,证明统计能量分析法能有效的预测板材隔声量。     

管道热边界层理论的研究

研究了高粘性液体管道流动的热边界层理论。利用圆柱坐标粘性流运动基本微分方程,提出了管道热边界层方程,推导出边界层中的温度分布以及层流和紊流时热边界层厚度的常微分方程和解析解计算表达式,并通过Matlab编程实例,给出了热边界层厚度解析解与数值解的比较。计算结果表明:1)粘性的影响将使得热边界层的发展加快,随着粘性和流量的增大,其影响将更加显著;2)紊流时热边界层的发展比层流时要慢。     

西北高海拔、高寒地区热媒研究

针对西北高海拔、高寒地区供热速度慢、热效率低等问题,研制出一种新型、高效热媒,热媒在一个大气压下沸点可达到116℃。通过单因素实验及正交实验,优化出了热媒配方;经热媒节能效果现场模拟实验,证明了所研制的热媒能显著改善供热效果;对热媒腐蚀性、风险性进行了分析。该热媒成本低、工艺简单、腐蚀性小、安全性高,具有很好的经济效益和军事效益。     

Bending and stress analysis of polymeric composite plates reinforced with functionally graded graphene platelets based on sinusoidal shear-deformation plate theory

The bending and stress analysis of a functionally graded polymer composite plate reinforced with gra-phene platelets are studied in this paper. The governing equations are derived by using principle of virtual work for a plate which is rested on Pasternak's foundation. Sinusoidal shear deformation theory is used to describe displacementfield. Four different distribution patterns are employed in our analysis. The analytical solution is presented for a functionally graded plate to investigate the influence of important parameters. The numerical results are presented to show the deflection and stress results of the problem for four employed patterns in terms of geometric parameters such as number of layers, weight fraction and two parameters of Pasternak's foundation.     

An experiment evaluating how the tiny mass eccentricities in spin-stabilized projectiles affect the position of impact points

This study investigates and quantifies some possible sources affecting the position of impact points of small caliber spin-stabilized projectiles (such as 12.7 mm bullets). A comparative experiment utilizing the control variable method was designed to figure out the influence of tiny eccentric centroids on the projectiles. The study critically analyzes data obtained from characteristic parameter measurements and precision trials. It also combines Sobol's algorithm with an artificial intelligence algorithm—Adaptive Neuro-Fuzzy Inference Systems (ANFIS)—in order to conduct global sensitivity analysis and determine which parameters were most influential. The results indicate that the impact points of projectiles with an entry angle of 0° deflected to the left to that of projectiles with an entry angle of 90°. The difference of the mean coordinates of impact points was about 12.61 cm at a target range of 200 m. Variance analysis indicated that the entry angle — i.e. the initial position of mass eccentricity — had a notable influence. After global sensitivity analysis, the significance of the effect of mass eccentricity was confirmed again and the most influential factors were determined to be the axial moment and transverse moment of inertia (Izz Iyy), the mass of a projectile (m), the distance between nose and center of mass along the symmetry axis for a projectile (Lm), and the eccentric distance of the centroid (Lr). The results imply that the control scheme by means of modifying mass center (moving mass or mass eccentricity) is promising for designing small-caliber spin-stabilized projectiles.     

Preparation and characterization of HMX/EVA/hBNNSs micro-composites with improved thermal stability and reduced sensitivity

Hexagonal boron nitride nanosheets(HBNNSs)have huge potential in the field of coating materials owing to their remarkable chemical stability,mechanical strength and thermal conductivity.Thin-layer hBNNSs were obtained by a liquid-phase exfoliation of h-BN powders and incorporated into EVA coatings for improving the safety performance of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).HBNNSs and ethylene-vinyl acetate copolymer(EVA)were introduced to HMX by a solvent-slurry process.For com-parison,the HMX/EVA and HMX/EVA/graphene(HMX/EVA/G)composites were also prepared by a similar process.The morphology,crystal form,surface element distribution,thermal decomposition property and impact sensitivity of HMX/EVA/hBNNSs composites were contrastively investigated.Results showed that as prepared HMX/EVA/hBNNSs composites were well coated with hBNNSs and EVA,and exhibited better thermal stability and lower impact sensitivity than that of HMX/EVA and HMX/EVA/G composites,suggesting superior performance of desensitization of hBNNSs in explosives.     

点火载荷下翼柱型装药结构完整性数值分析

针对固体火箭发动机翼柱型装药在点火载荷下结构完整性问题,提出了一种考虑三维损伤黏弹性本构性的数值模拟方法.基于商业有限元软件的二次开发平台,编写用户子程序,展开有限元数值计算,获取翼柱型装药在固化降温、点火载荷下装药结构的应力、应变与位移场分布.结果表明,在温度载荷与点火载荷下,药柱内表面变形模式是不同的.然而,不管在...     

潜艇自航模水下长波遥控系统

提出了利用无线长波对水下潜艇自航模进行长波遥控的通信技术,阐述了长波遥控的发射、接收及天线系统的硬件组成和系统设计。对发射天线的现场测试结果进行了分析,提出了实际电路的阻抗匹配实现方法;对接收信号的噪声和灵敏度等有关问题进行了分析,采用天线的方向性自适应控制技术解决了潜艇水下接收,在实际应用中取得较好的效果。     

AGWN信道中相关干扰对JTIDS接收机干扰效果分析

相关干扰是目前研究的对抗联合战术信息分发系统(JTIDS)比较有效的干扰样式,文中主要针对相关干扰对JTIDS接收机的干扰效果问题进行了深入研究。在建立了AGWN信道中相关干扰下JTIDS接收机模型的基础上,推导了接收机输出误比特率公式,并通过仿真和分析,得到了不同信噪比条件下接收机的最佳检测门限值以及误比特率与干信比的关系曲线,最后研究了干扰频偏对干扰效果的影响。研究表明,相关干扰对JTIDS接收机有着良好的干扰效果,并且对干扰频偏敏感。