粉末高温合金FGH96惯性摩擦焊接头常温力学性能分析

第二代粉末高温合金FGH96是采用损伤容限设计思想研制的新型粉末高温合金,是当前750℃工作条件下满足高推比、高燃效发动机使用要求的涡轮盘、环形件和其他热端部件的理想材料.结合FGH96惯性摩擦焊接头的组织特征和强化相γ′数量分析接头的显微硬度和常温拉伸性能.结果表明,FGH96惯性摩擦焊接头具有良好的常温力学性能.     

基于图形变形法的固体火箭发动机优化设计

基于图形变形法探索固体火箭发动机优化设计空间，通过可视化展示设计空间形态，能够提高固体火箭发动机优化设计效率和质量。采用试验设计方法对设计变量和约束条件重要性进行排序，简化优化模型；采用图形变形法对简化优化模型在不同试验设计点进行可视化分析；可视化选取可行设计空间中目标函数较小的点作为初始点。应用三种常规优化算法对4个不同初始点进行优化计算，计算结果表明，图形变形法优选的初始点使优化效率有不同程度的提高，优化结果具有更好的全局最优解特性；与遗传算法比较，效率提高400倍以上。     

Search radar detection and track with the Hough transform. II.detection statistics

For pt.I see ibid., vol.30, no.1, (Jan.1994). This paper describes the calculation of P_F and P_D for the Hough transform technique when the primary threshold crossings are weighted by their power before transforming (i.e., noncoherent integration). After expressions for P_F and P_D are derived, we examine the question of optimal granularity of the Hough accumulator space. We also investigate the relationship between primary and secondary thresholds and its effect on detectability     

Investigation of corona initiation voltage at reduced pressures

The results of an experimental study of the 60 Hz ac corona inception voltage at reduced pressures for a cylindrical conductor and a parallel ground plane are presented. Several spacings and bare and insulated conductors of several diameters are considered. Empirical expressions from which a reasonably accurate prediction of the corona inception voltage (CIV) may be made have been inferred from experimental data     

On the relation between the mass loss rate and the stellar parameters of OB-type stars

We discuss mass loss relations for OB-type stars as a function of luminosity, effective temperature, and mass. We conclude that a simple first order linear regression relation is as good as any other more sophisticated relation, with the advantage that the simple form consumes much less computer time when used in evolutionary codes.     

Light scattering in planetary atmospheres

This paper reviews scattering theory required for analysis of light reflected by planetary atmospheres. Section 1 defines the radiative quantities which are observed. Section 2 demonstrates the dependence of single-scattered radiation on the physical properties of the scatterers. Section 3 describes several methods to compute the effects of multiple scattering on the reflected light.     

Hard rock cosmic ray archaeology

Recent examinations of extraterrestrial materials exposed to cosmic rays for different intervals of time during the geological history of the solar system have generated a wealth of new information on the history of cosmic radiation. This information relates to the temporal variations in

1. the flux and energy spectrum of low energy (solar) protons of ? 10 MeV kinetic energy;
2. the flux and energy spectrum of (solar) heavy nuclei of Z > 20 of kinetic energy, 0.5–10 MeV/n;
3. the integrated flux of protons and heavier nuclei of ? 0.5 GeV kinetic energy, and
4. the flux and energy spectrum of nuclei of Z > 20 of medium energy — 100–2000 MeV/n kinetic energy.

The above studies are entirely based on the natural detector method which utilises two principal cosmogenic effects observed in rocks, (i) isotopic changes and (ii) changes in the crystalline structure of rock constituents, due to cosmogenic interactions. The information available to date in the field of hard rock cosmic ray archaeology refers to meteorites and lunar rocks/soil. Additional information based on study of cosmogenic effects in man-made materials exposed to cosmic radiation in space is also discussed. It is shown that the natural detectors inspite of their extreme simplicity have begun to provide cosmic ray information in a very quantitative and precise manner comparable to the most sophisticated electronic particle detectors. The single handicap in using the hard rock detectors is however the uncertainty regarding their manner of exposure, geometry etc. At present, a variety of techniques are being used to study the evolutionary history of extraterrestrial materials and as this field grows, uncertainties in cosmic ray archaeology will correspondingly decrease.     

用于被动寻的导弹的带末端落角约束的变结构导引律

使被动寻的导弹在较低的平飞弹道情况下，以较小的俯冲过载和最佳攻击姿态精确命中目标；采用带落角约束的变结构导引律，对弹目距离及距离变化率进行估计，克服被动寻的导弹不能测距的约束，同时使切换开关增益随时间自适应变化以减小俯冲过载；利用某型在研被动寻的导弹的气动参数，对此变结构导引律进行了数学仿真，仿真结果表明，在较低的平飞弹道约束条件下及过载要求范围内，该导引律能以期望落角命中静止与机动的坦克目标，对弹目距离变化率及距离的较大估计误差具有较强的鲁棒性。     

An Overview of the Fast Auroral SnapshoT (FAST) Satellite

The FAST satellite is a highly sophisticated scientific satellite designed to carry out in situ measurements of acceleration physics and related plasma processes associated with the Earth's aurora. Initiated and conceptualized by scientists at the University of California at Berkeley, this satellite is the second of NASA's Small Explorer Satellite program designed to carry out small, highly focused, scientific investigations. FAST was launched on August 21, 1996 into a high inclination (83°) elliptical orbit with apogee and perigee altitudes of 4175 km and 350 km, respectively. The spacecraft design was tailored to take high-resolution data samples (or `snapshots') only while it crosses the auroral zones, which are latitudinally narrow sectors that encircle the polar regions of the Earth. The scientific instruments include energetic electron and ion electrostatic analyzers, an energetic ion instrument that distinguishes ion mass, and vector DC and wave electric and magnetic field instruments. A state-of-the-art flight computer (or instrument data processing unit) includes programmable processors that trigger the burst data collection when interesting physical phenomena are encountered and stores these data in a 1 Gbit solid-state memory for telemetry to the Earth at later times. The spacecraft incorporates a light, efficient, and highly innovative design, which blends proven sub-system concepts with the overall scientific instrument and mission requirements. The result is a new breed of space physics mission that gathers unprecedented fields and particles observations that are continuous and uninterrupted by spin effects. In this and other ways, the FAST mission represents a dramatic advance over previous auroral satellites. This paper describes the overall FAST mission, including a discussion of the spacecraft design parameters and philosophy, the FAST orbit, instrument and data acquisition systems, and mission operations.     

The problem with aviation COTS

Commercial Off the Shelf (COTS) has become a byword for acquisition reform, but there are significant risks associated with the use of COTS products in military systems. These risks are especially acute for aviation systems. This paper explains how COTS can negatively affect military acquisitions and gives ideas on how to plan and resolve COTS caused problems