带损伤复合材料层压板剩余强度估算方法研究

 针对带损伤, 特别是冲击损伤的复合材料层压板的剩余强度估算, 提供易于工程使用 的思路和方法。包括: ① 提出了一种不依赖具体分析方法的统一的损伤记录与表征方法——损 伤数据结构DDS; ②提出了一种全新的缺口强度破坏判据——损伤影响(D I) 破坏判据; ③ 提出 了简单易用的估算冲击分层的弯曲应变能密度分层模型; ④提出了一套能够分析包括预埋分层 和冲击分层在内, 并能够处理单一分层以及多分层的损伤剩余强度估算方法。对共计12 种材料 体系、52 种铺层形式的开孔拉抻强度、预埋分层压缩强度及冲击后压缩强度进行了大量估算分 析, 与近百组试验结果相比均有良好一致性。     

机敏支撑结构的振动主动控制

 机敏结构是具有传感和执行双重功能的结构形式，无需外界帮助可自适应调节其状态。通过机敏结构建立了三维支撑结构的振动主动控制系统，利用Hamilton原理和变分法中的Euler公式导出了压电机敏结构的离散控制方程，采用加速度反馈实现了支架的振动主动控制。     

THE WIDE-BAND PLASMA WAVE INVESTIGATION

As part of the Cluster Wave Experiment Consortium (WEC), the Wide-Band (WBD) Plasma Wave investigation is designed to provide high-resolution measurements of both electric and magnetic fields in selected frequency bands from 25 Hz to 577 kHz. Continuous waveforms are digitised and transmitted in either a 220 kbit s^-1 real-time mode or a 73 kbit s^-1 recorded mode. The real-time data are received directly by a NASA Deep-Space Network (DSN) receiving station, and the recorded data are stored in the spacecraft solid-state recorder for later playback. In both cases the waveforms are Fourier transformed on the ground to provide high-resolution frequency-time spectrograms. The WBD measurements complement those of the other WEC instruments and also provide a unique new capability for performing very-long-baseline interferometry (VLBI) measurements.     

Near Infrared Spectrometer for the Near Earth Asteroid Rendezvous Mission

The Near-Infrared Spectrometer (NIS) instrument on the Near-Earth Asteroid Rendezvous (NEAR) spacecraft is designed to map spectral properties of the mission target, the S-type asteroid 433 Eros, at near-infrared wavelengths diagnostic of the composition of minerals forming S asteroids. NIS is a grating spectrometer, in which light is directed by a dichroic beam-splitter onto a 32-element Ge detector (center wavelengths, 816–1486 nm) and a 32-element InGaAs detector (center wavelengths, 1371–2708 nm). Each detector reports a 32-channel spectrum at 12-bit quantization. The field-of-view is selectable using slits with dimensions calibrated at 0.37° × 0.76° (narrow slit) and 0.74° × 0.76° (wide slit). A shutter can be closed for dark current measurements. For the Ge detector, there is an option to command a 10x boost in gain. A scan mirror rotates the field-of-view over a 140° range, and a diffuse gold radiance calibration target is viewable at the sunward edge of the field of regard. Spectra are measured once per second, and up to 16 can be summed onboard. Hyperspectral image cubes are built up by a combination of down-track spacecraft motion and cross-track scanning of the mirror. Instrument software allows execution of data acquisition macros, which include selection of the slit width, number of spectra to sum, gain, mirror scanning, and an option to interleave dark spectra with the shutter closed among asteroid observations. The instrument was extensively characterized by on-ground calibration, and a comprehensive program of in-flight calibration was begun shortly after launch. NIS observations of Eros will largely be coordinated with multicolor imaging from the Multispectral Imager (MSI). NIS will begin observing Eros during approach to the asteroid, and the instrument will map Eros at successively higher spatial resolutions as NEAR's orbit around Eros is lowered incrementally to 25 km altitude. Ultimate products of the investigation will include composition maps of the entire illuminated surface of Eros at spatial resolutions as high as 300 m.     

Effects of polarization and resolution on SAR ATR

Lincoln Laboratory is investigating the detection and classification of stationary ground targets using high resolution, fully polarimetric, synthetic aperture radar (SAR) imagery. A study is summarized in which data collected by the Lincoln Laboratory 33 GHz SAR were used to perform a comprehensive comparison of automatic target recognition (ATR) performance for several polarization/resolution combinations. The Lincoln Laboratory baseline ATR algorithm suite was used, and was optimized for each polarization/resolution case. Both the HH polarization alone and the optimal combination of HH, HV, and VV were evaluated; the resolutions evaluated were 1 ft/spl times/1 ft and 1 m/spl times/1 m. The data set used for this study contained approximately 74 km/sup 2/ of clutter (56 km/sup 2/ of mixed clutter plus 18 km/sup 2/ of highly cultural clutter) and 136 tactical target images (divided equally between tanks and howitzers).     

用隐式多重网格法计算三维粘性流动

求解高雷诺湍流流动时,边界层法向网格间距较流向和展向相比非常小,因此边界层中存在高度伸缩的网络,这将大大降低多重网格的求解效率。通过谐调的处理多重网格过程的各个细节,既提高了解的精度,又克服了网格展弦比的影响,使得计算效率提高了6～7倍。     

用极大似然法辨识轴对称飞行器的气动参数

采用极大似然法完成了轴对称飞行器的非线性气动参数辨识。根据飞行弹道的特性,采用考虑了横侧向运动耦合的纵向三自由度飞行动力学模型;为了反映气动参数随马赫数的变化,给出了一种考虑马赫数变化的气动参数数学模型,并采用了分段辨识的技巧;通过采用建模前估计法的辨识结果作为极大似然法的初值,保证了极大似然法的收敛,计算结果表明：这种算法对大攻角下的非线性气动参数能获得满意的辨识结果。     

雷达和红外成像双传感器信息融合目标识别研究

提出了一种利用目标的雷达和红外成像２种独立的传感器信息的互补性来构造特征向量的信息融合方法——联合向量空间法,并用对应的自适应信息融合系统进行目标识别。仿真证实比用单传感器的效果明显优越,从而说明了本文方法的有效性。     

液体推进剂一甲肼与水二元物系汽液相平衡的研究

一甲肼是一种重要的液体推进剂,分离反应过程所生成的水是确保一甲肼质量的关键。测定了甲基肼－水（ＭＭＨ－Ｈ２Ｏ）物系在１０１．３３ｋＰａ下的汽液平衡,以及电解质对其汽液平衡的影响。采用盐效应和溶剂化的方法,研究了不同电解质对ＭＭＨ－Ｈ２Ｏ汽液平衡的盐效应。