一种基于解析冗余关系的半定性故障隔离方法在航天器推进系统中的应用

针对航天器推进系统的时变特性以及随机因素给故障隔离带来的困难,提出了基于Z-检验分析和解析冗余关系相结合的半定性故障隔离方法。基于状态空间转换的思想,运用基于系统诊断键合图模型建立的解析冗余关系挖掘系统时不变的结构特征空间信息,并对解析冗余关系残差进行趋势分析获取时不变、具有残差变化方向的故障特征矩阵,针对存在随机因素对残差定性化的影响,利用了Z-检验分析对残差进行定性化获取观察特征,通过观测特征与故障特征的比较进行系统故障隔离。将该方法应用于推进系统的故障隔离中,结果证明了该方法能有效避免获取推进系统时变诊断准则以及来自系统建模和参数测量等随机因素的干扰,提高了推进系统故障隔离的鲁棒性。     

大型模拟对抗演习回放系统设计

针对大型模拟对抗演习的实际需要,提出了大型模拟对抗演习辅助讲评系统,对其子系统回放系统进行了重点设计。在分析系统功能的基础上,阐述了系统数据流程和可视化表现模式,论述了系统实现的关键技术,最终实现了回放系统。该系统通过对大型模拟对抗演习过程中产生的大量历史数据进行回放或展示,能够在演习结束或者阶段结束后辅助导演部或指挥员对演习过程作出全面客观的评价,从而达到帮助参演人员对演习过程进行分析评估、查找问题、总结经验和教训的目的。     

论朱德对我军战略战术形成与发展的重大贡献

朱德精辟阐述了以“群众战”为基本内容的人民战争思想,科学提出了红军进行游击战争的指导原则和作战方针,系统论述了抗日游击战战略战术,丰富和发展了我军在解放战争中的战术原则与战术运用,对我军战略战术的形成与发展具有历史性贡献。     

精密坐标镗床CNC系统研究

介绍了作者研制的通用ＣＮＣ系统,该系统以ＡＳＴ３８６作为控制器,采用ＰＷＭ驱动直流伺服电机,并配以软、硬件接口;文中对该系统的主要组成部分作了分析,在此基础上应用传统的ＰＩＤ控制方法设计数字控制器;最后通过实验验证了该系统的输出响应和控制器的性能。     

Survivability assessment of spacecraft impacted by orbit debris

To help optimize the spacecraft design and reduce the risk of spacecraft mission failure, a new approach to assess the survivability of spacecraft in orbit is presented here, including the following three steps:1) Sensitivity Analysis of spacecraft. A new sensitivity analysis method, a ray method based on virtual outer wall, is presented here. Using rays to simulate the debris cloud can effectively address the component shadowing issues. 2) Component Vulnerability analysis of spacecraft. A function"Component functional reduction degree — Component physical damage degree"is provided here to clearly describe the component functional reduction. 3) System-level Survivability Assessment of spacecraft. A new method based on expert knowledge reasoning, instead of traditional artificial failure tree method, is presented here to greatly improve the efficiency and accuracy of calculation.     

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.     

Insensitive energetic microspheres DAAF/RDX fabricated by facile molecular self-assembly

Insensitive energetic materials are promising in the defense weapons field. However, energetic materials still suffer from great challenges and the concern about their safety limits their utilization. In this work, insensitive energetic explosive 3,3′-diamino-4,4′-azoxyfurazan/hexahydro-1,3,5-trinitro-1,3,5-triazine (DAAF/RDX) microspheres were fabricated by self-assembly method. Rod-like DAAF/RDX was prepared by mechanical ball milling for comparison. DAAF/RDX composites with different mass ratios (90:10, 80:20, and 70:30) were obtained. The morphologies and structures of as-obtained DAAF/RDX composites were characterized by scanning electron microscopy (SEM), powder x-ray diffraction (PXRD) and fourier transform infrared spectroscopy (FT-IR). The results showed that DAAF/RDX microspheres exhibited regular shaped microspheres with sizes from 0.5 to 1.2 μm. There was no crystal transition during the modification process. The thermal properties of as-obtained materials were then evaluated by differential scanning calorimetry (DSC) and materials studio software. DAAF/RDX microspheres showed an advanced decomposition peak temperature compared with rod-like DAAF/RDX. The binding energy and peak temperature values at zero β_i (T_P0) of DAAF/RDX (90:10) increased by 36.77 kJ/mol, 1.6 °C, and 58.11 kJ/mol, 12.3 °C compared to DAAF/RDX (80:20) and DAAF/RDX (70:30), indicating the better thermal stability of DAAF/RDX (90:10). The characteristic drop height (H₅₀) of DAAF/RDX (higher than 100 cm) composites was higher than that of raw RDX (25 cm), suggesting significant improvements in mechanical safety. The preparation of DAAF/RDX microspheres is promising for the desensitization of RDX and useful for the formation of other materials and future wide applications.     

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.     

基于TensorFlow的四旋翼无人机着陆地标识别

针对多旋翼无人机在无人干预情况下的自主着陆问题,提出一种基于迁移学习的地面标识图像检测方法.该方法基于TensorFlow深度学习框架,使用迁移学习技术在地面标识数据集上重新训练Inception-v3模型以构建新的地面标识识别模型.以四旋翼无人机为例,将其拍摄的着陆坪图片与其他地面标识图片作为训练集输入神经网络,通过多次训练校正神经网络参数.实验结果表明,基于迁移学习的四旋翼无人机着陆地标识别比直接基于In-ception-v3模型的识别效果要好得多,在仅有数千张训练图片的情况下,测试准确率超过90％.在Windows下训练、测试的模型可移植到树莓派3B上,完成了基于Python和TensorFlow开发的程序在不同操作系统下运行的验证工作.     

国防科技工业企业信息模型的标准化思考

本文从国防科技工业企业信息化发展需要和信息技术应用标准化整体发展需要两个方面出发,论述了国防科技工业企业信息模型标准编制的必要性及作用,并提出了该系列模型标准的定位和整体框架,阐述了其标准化工作开展的思路与方法。