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在轨航天器故障检测与诊断问题需要面对模型的非线性,而且要求尽量提高其检测的精度,为此设计了基于径向基函数(RBF)神经网络的动量轮非线性故障检测与诊断(FDD)方案。首先应用RBF补偿建模误差,提高检测精度,并选择李雅普诺夫函数证明其收敛性;然后应用非线性观测器来产生故障残差,给出了阈值以及故障检测的时间;应用RBF网络对故障信号进行重构,并据此设计了带学习能力的FDD策略。再次建立了详细的动量轮模型,通过不同条件下的仿真研究分别验证残差的阈值特性、时间特性以及RBF的重构能力,仿真结果表明了算法的有效性。 相似文献
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135.
Pietro Ubertini Neil Gehrels Ian Corbett Paolo de Bernardis Marcos Machado Matt Griffin Michael Hauser Ravinder K. Manchanda Nobuyuki Kawai Shuang-Nan Zhang Mikhail Pavlinsky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The use of space techniques continues to play a key role in the advance of astrophysics by providing access to the entire electromagnetic spectrum from radio to high energy γ rays. The increasing size, complexity and cost of large space observatories places a growing emphasis on international collaboration. Furthermore, combining existing and future datasets from space and “ground based” observatories is an emerging mode of powerful and relatively inexpensive research to address problems that can only be tackled by the application of large multi-wavelength observations. While the present set of astronomical facilities is impressive and covers the entire electromagnetic spectrum, with complementary space and “ground based” telescopes, the situation in the next 10–20 years is of critical concern. The James Webb Space Telescope (JWST), to be launched not earlier than 2018, is the only approved future major space astronomy mission. Other major highly recommended space astronomy missions, such as the Wide-field Infrared Survey Telescope (WFIRST), the International X-ray Observatory (IXO), Large Interferometer Space Antenna (LISA) and the Space Infrared Telescope for Cosmology and Astrophysics (SPICA), have yet to be approved for development. 相似文献
136.
Ts.P. Dachev B.T. Tomov Yu.N. Matviichuk Pl.G. Dimitrov N.G. Bankov G. Reitz G. Horneck D.-P. Häder M. Lebert M. Schuster 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Space radiation has been monitored successfully using the Radiation Risks Radiometer-Dosimeter (R3D) installed at the ESA EXPOSE-R (R3DR) facility outside of the Russian Zvezda module of the International Space Station (ISS) between March 2009 and January 2011. R3DR is a Liulin type spectrometer–dosimeter with a single Si PIN detector 2 cm2 of area and 0.3 mm thick. The R3DR instrument accumulated about 2 million measurements of the absorbed dose rate and flux of 10 s resolution. The total external and internal shielding before the detector of R3DR device is 0.41 g cm−2. The calculated stopping energy of normally incident particles to the detector is 0.78 MeV for electrons and 15.8 MeV for protons. After the Coronal Mass Ejection (CME) at 09:54 UTC on 3 April 2010, a shock was observed at the ACE spacecraft at 0756 UTC on 5 April, which led to a sudden impulse on Earth at 08:26 UTC. Nevertheless, while the magnetic substorms on 5 and 6 of April were moderate; the second largest in history of GOES fluence of electrons with energy >2 MeV was measured. The R3DR data show a relatively small amount of relativistic electrons on 5 April. The maximum dose rate of 2323 μGy day−1 was reached on 7 April; by 9 April, a dose of 6600 μGy was accumulated. By the end of the period on 7 May 2010 a total dose of 11,587 μGy was absorbed. Our data were compared with AE-8 MIN, CRESS and ESA-SEE1 models using SPENVIS and with similar observations on American, Japanese and Russian satellites. 相似文献
137.
为实现对航天器热平衡试验平衡温度的预测,建立了热平衡温度预测的方程式,对影响预测结果的各参数进行了分析。首先,由节点网络法推导出平衡温度表达式,介绍了其基于非线性最小二乘法的求解过程,建立了平衡温度的迭代方程;其次,结合大量的试验数据,对影响迭代结果的3个因素进行了统计分析,并最终确定了各因素的合理取值范围;最后,利用温度预测程序对某空间相机热平衡试验中低温工况的平衡温度进行了预测,并与试验结束后的结果进行了对比。结果表明,预测温度与试验数据的误差为±1℃(在3%之内),满足精度要求,对热平衡温度准确的预测有效的缩短了试验时间,节省试验费用。 相似文献
138.
为研究宇宙辐射环境中航天器里的模拟互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)集成电路性能和各种效应,并在辐射效应所产生机制的基础上,从设计和工艺方面提出了模拟CMOS集成电路主要抗辐射加固设计方法.在宇宙环境中,卫星中的模拟CMOS集成电路存在CMOS半导体元器件阈值电压偏离、线性跨导减小、衬底的漏电流增加和转角1/f噪声幅值增加.所以提出了3种对模拟CMOS集成电路进行抗辐射加固的方法:1)抗辐射模拟CMOS集成电路的设计;2)抗辐射集成电路版图设计;3)单晶半导体硅膜(Silicon on Insulator,SOI)抗辐射工艺与加固设计.根据上面的设计方法研制了抗辐射加固模拟CMOS集成电路,可以取得较好的抗辐射效果. 相似文献
139.
María G. Molina M.A. Cabrera R.G. Ezquer P.M. Fernandez E. Zuccheretti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Numerical solutions for signal processing are described in this work as a contribution to study of echo detection methods for ionospheric sounder design. The ionospheric sounder is a high frequency radar for geophysical applications. The main detection approach has been done by implementing the spread-spectrum techniques using coding methods to improve the radar’s range resolution by transmitting low power. Digital signal processing has been performed and the numerical methods were checked. An algorithm was proposed and its computational complexity was calculated. 相似文献
140.
Ali G. Hafez Essam Ghamry Hideki Yayama Kiyohumi Yumoto 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Geomagnetic storm sudden commencements (SSC) contain a wealth of information which is useful in many applications. It is important to point out that the SSCs used in this study are sampled at the rate of one sample per second in order get use of such high resolution data. In this paper, two studies are made on the geomagnetic SSC and an SSC onset automatic detection algorithm is introduced. The first study is about finding the relationship between the SSC rise time and its amplitude. Where it is found that there is a positive correlation between the amplitude and the amplitude gradient which is the amplitude divided by rise time. The second study is checking the spectrum of the SSC, starting from its onset until the end of the SSC rise time. This check had proved that the SSC contains both low and high frequency regions. This led us to introduce a new term, namely the SSC variation rate (VR). This VR is defined as the maximum rate of change of the field in the higher-frequency region of the SSC. These two studies were the guide to build an SSC automatic detector of one sample per second data using multi resolution analysis (MRA) of the discrete wavelet transform (DWT). The data set contains 134 SSCs with different VRs that were collected from the Circum-pan Pacific Magnetometer Network (CPMN). It is found that the standard deviation of the detection error is 41 s and that the average error is 9 s. From the calculated error distribution function, it is found that the detection error is within the range of −1.5 to 3 min. The detection process, as will be shown in the article, takes 70 s for one station and 3 min if the decision is related to the detection(s) of other stations. These results demonstrate the superiority of the proposed algorithm over other algorithms in which the detection error ranges between −8 and 5 min and the detection process takes 2–10 min. In addition to being faster and more accurate than the other algorithms, the proposed algorithm is the first algorithm that automatically detects the SSC onset times from high-resolution data unlike previous studies that focused on determining the SSC times automatically using one-minute resolution data. 相似文献