可压缩流体恒温热线风速仪校准方法

开展了恒温(CT)热线风速仪校准方法的研究,以满足可压缩流体中湍流度测量需求。将对数函数与多元回归技术相结合,建立了恒温热线风速仪校准的数学模型,并进行了风洞湍流度测量试验验证。在马赫数Ma=0.3~0.55范围内进行了校准试验,根据建立的数学模型对试验数据进行拟合,拟合优度R2=0.999 82,平均绝对速度偏差Δu=0.18m/s,基本满足了恒温热线风速仪校准精度要求。对马赫数Ma=0.55条件下流场进行了湍流度测量,速度测量偏差为0.034%,流场湍流度Tu=0.14%。试验结果证明了恒温热线风速仪应用于可压缩流体速度测量的可行性。     

Constant power H∞ stabilization control strategy on airborne pump supplying system

以机载泵源系统的恒功率控制为目标，针对作业任务中系统负载随时间变化的情况，采用使液压系统输出功率保持恒定的控制方式来达到充分利用发动机功率的目的，对于机载泵源控制系统的主要被控对象——轴向柱塞式变量泵，建立了其状态方程和流量输出方程，采用H。鲁棒镇定控制策略实时调节泵的排量，仿真结果表明：当负载变化时，系统能根据压力的变化快速转换到恒功率工作曲线下对应的流量状态，所设计的H。控制器能够减小干扰和模型参数不确定对系统稳定性的影响，具有良好的鲁棒性，表明该方法用于机载液压系统可以改善系统工作性能，提高系统功率的利用率。     

GaAs的光学常数的计算

为深入认识GaAs的光学性质,采用从头算法计算其电子结构,并依据线性响应理论计算出它的复介电常数,进而得到复折射率,反射系数,吸收系数等光学常数。     

飞机铆接电阻专用测量仪的研制

飞机铆接电阻专用测量仪是用于测量飞机铆接部件接触质量的专用仪器,它对保证飞机机载电子设备和通讯系统正常工作具有重要作用,在飞机维护中也常常要检测机体电阻是否符合要求.本文介绍了该测量仪的研制目的、工作原理和电路组成.     

Effects of a “day-time” substorm on the ionosphere and radio propagation

Propagation mechanisms of lateral (non-great-circle) signals on a high-latitude HF radio path during magnetospheric substorms that occurred in the day-time have been considered. The path is equipped with oblique ionospheric sounding (OIS) from Murmansk to St. Petersburg. The OIS method gives the possibility to determine propagation modes, MOF (maximum observed frequency) values, signal delays, etc. Data of the CUTLASS radar, the IMAGE magnetometer system, the Finnish riometer chain, and the Tromso ionosonde were also used for the analysis. The main results are the following: (1) the lateral signal propagation takes place, as a rule, if the path midpoint is located near the irregularity region that moves sharply from high to low latitudes. The lateral signal propagation appearing during day-time is a new effect. (2) Formation of dense field-aligned irregularities during a substorm leads to decreasing F2MOF values on radio paths. These results can be useful for problems of radiolocation, HF communications and navigation.     

Anthropogenic trigger of substorms and energetic particles precipitations

The high-frequency (HF) emission in near-Earth space from various powerful transmitters (radio communications, radars, broadcasting, universal time and navigation stations, etc.) form an integral part of the modern world that it cannot do without. In particular, special-purpose research facilities equipped with powerful HF transmitters are used successfully for plasma experiments and local modification of the ionosphere. In this work, we are using the results of a complex space-ground experiment to show that exposure of the subauroral region to HF emission can not only cause local changes in the ionosphere, but can also trigger processes in the magnetosphere–ionosphere system that result in intensive substorm activity (precipitations of high-energy particles, aurorae, significant variations in the ionospheric parameters and, as a consequence, in radio propagation conditions).     

含天然与人工内部缺陷轮盘裂纹扩展特性对比分析

为达到应用人工内部缺陷获得轮盘裂纹扩展特性，开展了含天然与人工内部缺陷轮盘高速旋转低周疲劳裂纹扩展对比试验，并通过无损检测分析、断口分析研究了裂纹扩展特性的差异，提出了含人工缺陷轮盘损伤容限分析思路。无损检测更易识别人工内部缺陷的特征及其变化；人工缺陷区呈碎裂状，有大量的晶间断裂，与天然缺陷区有明显差异；非缺陷区两者无明显差异。天然与人工缺陷区的裂纹扩展速率分别为0.2-0.4μm/次、0.6-1.2μm/次，均远大于基体材料理论值；1#盘加载突变区外断口反推寿命与第二加载阶段循环数的最大误差是12%；2#盘缺陷区外断口反推寿命占总循环数的44.9%-51.9%。基于人工缺陷区定义初始裂纹，排除人工与天然缺陷差异的影响，可获得轮盘裂纹扩展特性。     

Match-mode method and its numerical simulation for rotor-stator interaction source modes and propagation modes in an annular duct with multi-treatments

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Cosmic ray flux at the Earth in a variable heliosphere

In recent years the variability of the cosmic ray flux has become one of the main issues not only for the interpretation of the abundances of cosmogenic isotopes in cosmochronic archives like, e.g., ice cores, but also for its potential impact on the terrestrial climate. It has been re-emphasized that the cosmic ray flux is not only varying due to the solar activity-induced changes of the solar wind but also in response to the changing state of the interstellar medium surrounding the heliosphere. We demonstrate the significance of these external boundary condition changes along the galactic orbit of the Sun for the flux as well as spectra of cosmic rays. Such interstellar–terrestrial relations are a major topic of the International Heliophysical Year 2007.     

极坐标系连续常值推力机动分析

连续常值推力是空间飞行常用的轨道机动方式，在空间交会与星际航行使命中具有重要的应用价值。其中，小推力适合于地球轨道航天器交会机动，而切向或周向推力以及较大的正径向推力可用于脱离地球引力场的逃逸飞行，执行星际交会使命。应用常推力作用下的极坐标系质心运动方程，对机动推力的量值没有限制；在航天器交会应用中，对相对距离也无要求。这种方法可直接获得向径与速度等轨道参数随时间或极角（绕地心的转动角）的变化，便于分析轨道转移与逃逸运动，有助于飞行使命与运动轨迹的设计。特别是，若机动转移的初轨为圆轨道，在推力较小、飞行时间不长的情况下，应用无量纲形式运动方程，可获得具有工程应用价值的近似解。文章给出一些有关的结果与应用案例。