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791.
中段弹道目标的温度场与红外辐射特性计算   总被引:1,自引:0,他引:1  
申文涛  朱定强  蔡国飙 《宇航学报》2010,31(9):2210-2217
红外辐射特性是预警系统探测识别弹道中段目标的重要特征之一。通过计算飞行时目标与太阳、地球的相对位置,确定目标的受外辐射照射状态。利用有限容积法计算锥形目标的三维温度场,采用双向反射分布函数(BRDF)计算目标表面对太阳、地球辐射的反射特性,并结合自身红外辐射,得到了不同类型中段目标红外辐射特性变化情况和空间分布情况。最后,分析了外部辐射环境和目标材料特性对目标红外辐射特性的影响,为中段预警探测提供了参考。  相似文献   
792.
在原子氧剥蚀效应地面模拟设备中对一种抗原子氧复合材料β布进行了原子氧剥蚀效应试验、试样湿度升高对原子氧效应的影响试验以原子氧与紫外辐射复合效应试验研究,对试验前后β布试样的质量及表面形貌进行了比较,得出了在材料在设备中的反应特点以及温度变化、紫外辐射对材料的原子氧效应的影响规律。另外对这种材料与原子氧的反应机理进行了分析,得出了一些有意义的结论。  相似文献   
793.
复杂边界条件下的多层多孔壁温度场的计算模型   总被引:3,自引:0,他引:3  
经过推导给出了具有孔内和内外表面对流换热及外表面热辐射复杂边界条件下的多层多孔壁温度场的计算模型,并以具有陶瓷隔热涂层的全气膜覆盖气冷叶片为例进行了温度场计算。计算结果表明:陶瓷涂层具有明显的隔热效果,并可明显地减小冷却空气用量;燃气温度对壁温影响较大;考虑热辐射将更加符合实际物理过程;对于涡轮叶片若不考虑热辐射将低估壁温 1. 5% ~3. 5% 。该模型可用于多层多孔壁冷却结构形式的发动机高温部件的优化设计。  相似文献   
794.
真空紫外线辐射对聚合物材料的作用   总被引:3,自引:1,他引:3       下载免费PDF全文
针对空间环境条件综述了真空紫外线辐射对材料物理、化学等性能的影响及机理。聚合物材料在真空紫外线作用下,表面粗糙度上升,结构发生明显变化,拉伸强度下降。同时透光率、耐热性等均发生变化。真空紫外线与原子氧等其它空间环境因素有一定程度的协同效应。不同材料对各因素的敏感程度稍有差异。  相似文献   
795.
在空间恶劣环境下要求星载高稳晶振正常有效地工作,需要对其在空间辐照环境下的频率特性变化进行研究,利用地面辐照设备模拟空间辐照环境,通过不断增加辐照剂量,研究晶振相位噪声、短期频率稳定度、谐杂波以及输出功率等特性。  相似文献   
796.
The radiation environment at the altitude of the International Space Station (ISS) is substantially different than anything typically encountered on Earth in both the character of the radiation field and the significantly higher dose rates. Concerns about the biological effects on humans of this highly complex natural radiation field are increasing due to higher amount of astronauts performing long-duration missions onboard the ISS and especially if looking into planned future manned missions to Mars. In order to begin the process of predicting the dose levels seen by the organs of an astronaut, being the prerequisite for radiation risk calculations, it is necessary to understand the character of the radiation environment both in- and outside of the ISS as well as the relevant contributions from the radiation field to the organ doses.  相似文献   
797.
Space weather and related ionizing radiation has been recognized as one of the main health concerns for the International Space Station (ISS) crew. The estimation of the radiation effect on humans outside the ISS requires at first order accurate knowledge of their accumulated absorbed dose rates, which depend on the global space radiation distribution, solar cycle and local variations generated by the 3D mass distribution surrounding the ISS. The R3DE (Radiation Risks Radiometer-Dosimeter for the EXPOSE-E platform) on the European Technological Exposure Facility (EuTEF) worked successfully outside of the European Columbus module between February 2008 and September 2009. A very similar instrument named R3DR for the EXPOSE-R platform worked outside the Russian Zvezda module of the ISS between March 2009 and August 2010. Both are Liulin-type detectors, Bulgarian-built miniature spectrometer-dosimeters. The acquired approximately 5 million deposited energy spectra from which the flux and absorbed dose rate were calculated with 10 s resolution behind less than 0.41 g cm−2 shielding. This paper analyses the spectra collected in 2009 by the R3DE/R instruments and the long-term variations in the different radiation environments of Galactic Cosmic Rays (GCR), inner radiation belt trapped protons in the region of the South Atlantic Anomaly (SAA) and relativistic electrons from the Outer Radiation Belt (ORB). The R3DE instrument, heavily shielded by the surrounding structures, measured smaller primary fluxes and dose rates from energetic protons from the SAA and relativistic electrons from the ORB but higher values from GCRs because of the contribution from secondary particles. The main conclusion from this investigation is that the dose rates from different radiation sources around the International Space Station (ISS) have a large special and temporal dynamic range. The collected data can be interpreted as possible doses obtained by the cosmonauts and astronauts during Extra Vehicular Activities (EVA) because the R3DE/R instruments shielding is very similar to the Russian and American space suits average shielding (,  and ). Fast, active measurements are required to assess accurately the dose accumulated by astronauts during EVA.  相似文献   
798.
为提高导航卫星精密定轨与轨道预报精度,提出了一种导航卫星太阳光压摄动的分析建模方法.相较于其他摄动因素模型完善且精度较高,光压摄动由于太阳活动导致太阳能量误差、卫星姿态控制误差和表面材料老化等问题,是最难以精确建模的摄动源,也是动力学模型最大的误差源.基于此,提出了一种基于卫星的姿态控制规律,通过分析法建立卫星太阳光压摄动模型,给出了光压摄动加速度在星体坐标系中的模型,并以GPSBlock IIR为例进行了验证.计算结果表明,该仿真分析法所建立的摄动模型与T30模型、ECOM模型精度接近,达到了光压建模研究的初步计算要求.  相似文献   
799.
Radiation in low Earth orbit (LEO) is mainly composed of galactic cosmic rays (GCR), solar energetic particles and particles in SAA (South Atlantic Anomaly). The biological impact of space radiation to astronauts depends strongly on the particles’ linear energy transfer (LET) and is dominated by high LET radiation. It is important to measure the LET spectrum for the space radiation field and to investigate the influence of radiation on astronauts. At present, the preferred active dosimeters sensitive to all LET are the tissue equivalent proportional counter (TEPC) and the silicon detectors in various configurations; the preferred passive dosimeters are CR-39 plastic nuclear track detectors (PNTDs) sensitive to high LET and thermoluminescence dosimeters (TLDs) as well as optically stimulated luminescence dosimeters (OSLDs) sensitive to low LET. The TEPC, CR-39 PNTDs, TLDs and OSLDs were used to investigate the radiation field for the ISS mission Expedition 13 (ISS-12S) in LEO. LET spectra and radiation quantities (fluence, absorbed dose, dose equivalent and quality factor) were measured for the space mission with different dosimeters. This paper introduces the role of high LET radiation in radiobiology, the operational principles for the different dosimeters, the LET spectrum method using CR-39 detectors, the method to combine the results measured with TLDs/OSLDs and CR-39 PNTDs, and presents the LET spectra and the radiation quantities measured and combined.  相似文献   
800.
梁飞  効迎春  鲁楠  朱峰 《航空学报》2020,41(8):323705-323705
为了分析电气化铁路高速列车电分相电弧对机场全向信标(VOR)的影响,研究其电磁发射特性。利用电磁干扰接收机与频谱仪,分别以点频和扫频方式,对电气化铁路电分相点和普通点进行了大量辐射测试。分析测试数据的异方差性,改进回归分析方法,拟合出电弧在全向信标频段的幅频特性曲线,分析弓网电弧电磁辐射对机场全向信标的影响。结果表明:电分相电磁辐射是随机的,在电分相处比普通点大;现代电气化铁路高速列车经过电分相的测试数据异方差性比较明显,普通的最小二乘估计方法不适用;当电气化铁路电分相点与飞机距离小于4.944 km时,可能会对VOR信号产生影响。  相似文献   
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