带落角约束的新型二阶滑模三维制导律

针对导弹在三维空间中攻击地面机动目标问题,提出了一种带落角约束的三维有限时间制导律。为提高收敛速度和抑制抖振现象,基于非齐异快速终端滑模面和二阶滑模控制理论设计了含耦合项的非奇异快速终端二阶滑模三维制导律,设计过程中无需对系统模型作线性化处理并且避免了奇异问题的出现。针对目标机动信息和视线角耦合带来的总扰动,设计了非齐次干扰观测器进行估计并补偿。并对制导律的稳定性和有限时间收敛特性进行了严格的数学证明。仿真验证了本文提出制导律的有效性和优越性。      

Fe3Al基合金拉伸和蠕变性能的改进

研究了合金化对Fe3Al力学性能的影响,结果表明加入微量的Ce对提高Fe3Al基合金室温塑性非常有效果.通过X-射线光电子能谱表层分析证明了微量Ce的加入改变了氧化物的化学组成,从而使试样表面快速钝化.用W,Ni或者Mo,尤其是W与Ni或者W与Mo复合合金化可以使Fe3Al基合金的高温强度和蠕变抗力明显提高.W、Ni或者Mo的加入会明显改善合金的微观组织,它们在合金中能够形成含有W的类似M6C碳化物形式的沉淀相.     

Si3N4/SiC纳米复合材料的制备力学性能及强韧化机理

ＳｉＣ纳米粒子进入Ｓｉ３Ｎ４基体使其力学性能大幅度增高,引起了研究者有大关注,本文评述了Ｓｉ３Ｎ４／ＳｉＣ纳米复合材料的制备工芤及其力学性能,分析了力学性能提高的主要原因,讨论了材料中存在的强化增韧机理。     

1N ADN基推力器瞬态启动性能试验研究

为研究1N ADN基推力器的瞬态启动性能,给推力器在轨使用提供参考,通过设计推力器高空模拟热试车系列工况,研究了催化床不同预热温度、喷注压力、不同寿命阶段推力器的瞬态启动性能,获得不同条件下推力器开机加速性t90指标.结果表明1N ADN基推力器t90随预热温度的上升呈现先减小后增大的趋势;推力器喷注压力降低,t90变大;同时,研究了ADN基 推进剂地面存储时长对推力器的瞬态启动性能的影响,实验结果显示在存贮时间内,推力器t90指标保持稳定.     

基于三维点云重建的助推器位姿估计

助推器分离是运载火箭发射过程中的关键动作之一,常用的激光雷达姿态测量技术在助推器分离阶段受外界干扰严重,难以准确获得位姿。基于视觉的助推器位姿变化测量技术具有优秀的抗干扰能力,通过搭建三维点云重建网络,以图像为输入,三维点云为输出,在构建的助推器分离过程的图像 点云数据上进行了训练和测试,对测试重建的助推器点云使用主成分分析的方法完成了位姿的估算。测试结果表明,所建立的三维点云重建网络可以根据仿真图像数据,精确测量助推器分离阶段的位姿变化,在R2score指标下,对三维坐标的预测分数均在0.98以上,姿态角平均误差约为21°,预测分数则均在0.80以上。     

Al_2O_（3P）／Zn－Al复合材料的硬度与耐磨性能

研究了流变铸造法制备的Ａｌ２Ｏ３Ｐ／Ｚｎ－Ａｌ复合材料硬度和耐磨性能。结果表明Ａｌ２Ｏ３Ｐ的加入，提高了Ｚｎ－Ａｌ合金的室温和高温硬度，改善了其耐磨性能。颗粒体积含量增加，或者颗粒粒径的减小都将提高该复合材料的硬度和耐磨性，而试验温度的增加会引起其硬度的迅速降低。不过，Ａｌ２Ｏ３Ｐ的加入显著改善了Ｚｎ－Ａｌ合金耐高温性能。此外，文中还研究了淬火、回火或循环热处理对该复合材料硬度值的影响。     

Radio occultation electron density profiles from the FORMOSAT-3/COSMIC satellites over the Brazilian region: A comparison with Digisonde data

This study aims to validate the electron density profiles from the FORMOSAT-3/COSMIC satellites with data from Digisondes in Brazil during the low solar activity period of the years 2006, 2007 and 2008. Data from three Brazilian Digisondes located in Cachoeira Paulista (22.7°S, 45°W), São Luís (2.5°S, 44.2°W) and Fortaleza (3.8°S, 38°W) were used in the comparisons. Only the profiles whose density peak have been obtained near the stations coordinates were chosen for the comparison. Although there is generally good agreement, some cases of discrepancies are observed. Some of these discrepancies cannot be explained simply by the differences in the position and local time of the measurements made by the satellite and the ground-based station. In such cases it is possible that local conditions, such as the presence of a trans-equatorial wind or electron density gradients, could contribute to the observed differences. Comparison of the F2 layer peak parameters, the NmF2 and hmF2, obtained from the two techniques showed that, in general, the agreement for NmF2 is pretty good and the NmF2 has a better correlation than hmF2. Cachoeira Paulista had the worst correlation for hmF2 possibly because this station is situated in the region under the influence of the equatorial ionization anomaly, a region where it is more difficult to apply the RO technique without violating the spherical symmetry condition.     

Metallic and Oxidized Aluminum Debris Impacting the Trailing Edge of the Long Duration Exposure Facility (LDEF)

A total of 87 microcraters >30 m in diameter that were found in gold substrates exposed on the trailing edge of the non-spinning Long Duration Exposure Facility (LDEF) yielded analyzable projectile residues in their interiors. Using qualitative SEM-EDS analysis methods, some 60 of these craters were formed by natural cosmic-dust particles, while 27 residues (31%) were assigned to orbital debris (Hörz et al., 1993). The far majority of the orbital-debris impacts, 24 (89%) of the 27 events, contained only aluminum in their X-ray spectra. The present study evaluates these aluminum-rich residues in detail and employs a windowless X-ray detector, which permits for the analysis of low-Z elements and specifically of oxygen. This makes it possible to discriminate between oxidized (Al₂O₃) and metallic (Al) projectiles from dramatically different sources, the former produced during solid-fuel rocket firings, the latter resulting from explosively or collisionally disrupted spacecraft.Of the 24 craters analyzed with the windowless detector, 13 (54%) contained Al₂O₃ and 11 (46%) yielded structurally disintegrated Al metal. The oxidized residues preferentially occur in the smaller craters, all <60 m in diameter. Corresponding particles on LDEF's trailing edge are <35 m in diameter. Some 70% of this particle population is composed of Al₂O₃. Although solid-fuel rocket exhaust products are typically <5 m in size, they tend to coagulate into crusts at the rocket nozzle to be shed occasionally as relatively large, aggregate particles. Structurally disintegrated, metallic fragments compose one-third of all particles <35 m, but they dominate all particles >35 m, and thus all craters >60 m. These findings clearly establish that solid-rocket exhaust particles, as well as explosively or collisionally produced debris, exist in low-inclination, high-eccentricity orbits in sufficient quantities that they must be accounted for in models describing the present and future orbital-debris population at typical Shuttle and Space Station altitudes.     

利用偏移矩阵提高CBERS图像预处理几何定位精度的方法研究

偏移矩阵是指由于传感器与卫星平台之间的安装偏差而导致的传感器坐标系与卫星平台坐标系之间的旋转矩阵 ,用于校正传感器与卫星平台坐标系之间不重合而导致的成像偏差。针对CBERS卫星数据处理系统只能使用星上下传姿态和星历数据进行预处理 ,而这些姿态和星历数据也可能存在系统误差的情况 ,我们把预处理图像所有引入误差 ,包括系统安装误差、姿态和星历数据误差、地面处理模型误差等 ,综合导致的成像偏差 ,归结为一个旋转矩阵来校正 ,该旋转矩阵定义为偏移矩阵。当系统成像存在一个较大的系统误差时 ,把该偏移矩阵代入几何校正处理模型中 ,可以得到很好的校正效果。文章方法在CBERS卫星的在轨测试中得到实施并取得较好的效果 ,增加偏移矩阵校正后 ,图像预处理几何定位精度得到显著提高     

新一代机载数据采集器设计思路及应用技术探讨

KAM500采集系统设计思想先进,使用了现代计算机技术和现场可编程逻辑器件,具有各通道同步采样, 数据采集、传输与编码相对独立,数字滤波,利用LOOKUP表进行非线性补偿、调节等特点。该系统通过KSMV2软件进 行编程、管理和数据检查。