On the Accuracy of the Conjugation of High-Orbit Satellites with Small-Scale Regions in the Ionosphere

The degree of uncertainty that arises when mapping high-orbit satellites of the Cluster type into the ionosphere using three geomagnetic field models (T89, T98, and T01) has been estimated. Studies have shown that uncertainty is minimal in situations when a satellite in the daytime is above the equatorial plane of the magnetosphere at the distance of no more than 5 R_E from the Earth’s surface and is projected into the ionosphere of the northern hemisphere. In this case, the dimensions of the uncertainty region are about 50 km, and the arbitrariness of the choice of the model for projecting does not play a decisive role in organizing satellite support based on optical observations when studying such large-scale phenomena as, e.g., WTS, as well as heating experiments at the EISCAT heating facility for the artificial modification of the ionosphere and the generation of artificial fluctuations in the VLF band. In all other cases, the uncertainty in determining the position of the base of the field line on which the satellite is located is large, and additional information is required to correctly compare the satellite with the object in the ionosphere.     

Using the Subsurface Soil Sounding Radar for Investigating the Structure and Total Electron Content of the Martian Ionosphere

The possibilities of using the Martian soil subsurface sounding radar for investigating the structure of the plasma shell surrounding the planet have been considered. Based on the numerical modeling results and actual soil sounding data, it has been shown that the soil sounding mode of the radio-locating MARSIS radar can be used to assess the structure of the Martian ionosphere. As the emitted signals pass to the planet’s surface, it is possible to use the reflected signals to estimate the total electron content of the Martian ionosphere along the flight track of the spacecraft.     

航空电子产品的BAYES可靠性评估

针对航空电子产品可靠性评估问题, 确定了环境因子的分布, 把模拟试验信息通过环境因子折合得到了可靠性的预测分布。利用此预测分布作为验前分布结合飞行试验信息得到可靠性的验后分布。仿真算例表明这种方法比经典统计方法和传统BAYES方法更合理     

电子产品中铅焊接金脆问题浅析

针对航天电子产品广泛采用的Sn-Pb焊料在镀金表面焊接形成焊点的工艺,分析了工业及国内外航天相关标准文件中对焊接后焊点中含金量的要求以及焊点含金量、时效、器件不同封装形式对焊点可靠性的影响,并深入分析了合金焊点金相组织结构,最后介绍了一般去金工艺要求与去金不到位而导致器件失效案例。     

电磁辅助激光熔化沉积的残余应力

针对激光熔化沉积内部残余应力较大的问题,对其产生的机理作了分析。基于电磁场的应用原理,提出电磁辅助激光熔化沉积以降低其残余应力的方法。利用ANSYS参数化编程语言APDL模拟了电磁辅助激光熔化沉积的过程,分析了成形件残余应力的变化规律,结果表明同步加载轴向电磁力能较好地消减成形件内部残余应力。采用X射线衍射结合电解腐蚀的方法进行深度方向的残余应力测量试验,试验结果验证了电磁辅助的有效性。     

Studying the change in characteristics of optical surfaces of a spacecraft

The change in the working characteristics of the optical element sample depending on the thickness of the contamination film applied to the sample has been estimated experimentally. As sources of contamination, the coatings of lens hoods were chosen, which are located in close proximity to the contamination- sensitive optical system of a spacecraft. A series of experiments for applying contamination films of different thickness to the sample of the optical element has been carried out. Based on preliminary estimations, the thickness of the contamination during the entire period of the active existence of the spacecraft will not exceed 3500 Å.     

The Juno Radiation Monitoring (RM) Investigation

The Radiation Monitoring Investigation of the Juno Mission will actively retrieve and analyze the noise signatures from penetrating radiation in the images of Juno’s star cameras and science instruments at Jupiter. The investigation’s objective is to profile Jupiter’s \(>10\mbox{-MeV}\) electron environment in regions of the Jovian magnetosphere which today are still largely unexplored. This paper discusses the primary instruments on Juno which contribute to the investigation’s data suite, the measurements of camera noise from penetrating particles, spectral sensitivities and measurement ranges of the instruments, calibrations performed prior to Juno’s first science orbit, and how the measurements may be used to infer the external relativistic electron environment.     

Hybrid uncertainty-based design optimization and its application to hybrid rocket motors for manned lunar landing

Design reliability and robustness are getting increasingly important for the general design of aerospace systems with many inherently uncertain design parameters. This paper presents a hybrid uncertainty-based design optimization (UDO) method developed from probability theory and interval theory. Most of the uncertain design parameters which have sufficient information or experimental data are classified as random variables using probability theory, while the others are defined as interval variables with interval theory. Then a hybrid uncertainty analysis method based on Monte Carlo simulation and Taylor series interval analysis is developed to obtain the uncer-tainty propagation from the design parameters to system responses. Three design optimization strategies, including deterministic design optimization (DDO), probabilistic UDO and hybrid UDO, are applied to the conceptual design of a hybrid rocket motor (HRM) used as the ascent propulsion system in Apollo lunar module. By comparison, the hybrid UDO is a feasible method and can be effectively applied to the general design of aerospace systems.     

Influence of Simplifying a Geometrical Model of the Gas Turbine Engine Combustion Chamber on the Results of Numerical Modeling

We studied the geometric models of combustion chambers depending on their simplification. It is shown that the error in calculating the parameters does not exceed 8 % under the constraint of the geometrical model of the gas turbine engine (GTE) combustion chamber by an angular sector with a burner device.