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571.
Myung-Hee Y. Kim Garry D. Qualls Tony C. Slaba Francis A. Cucinotta 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
For the evaluation of organ dose and dose equivalent of astronauts on space shuttle and the International Space Station (ISS) missions, the CAMERA models of CAM (Computerized Anatomical Male) and CAF (Computerized Anatomical Female) of human tissue shielding have been implemented and used in radiation transport model calculations at NASA. One of new human geometry models to meet the “reference person” of International Commission on Radiological Protection (ICRP) is based on detailed Voxel (volumetric and pixel) phantom models denoted for male and female as MAX (Male Adult voXel) and FAX (Female Adult voXel), respectively. We compared the CAM model predictions of organ doses to those of MAX model, since the MAX model represents the male adult body with much higher fidelity than the CAM model currently used at NASA. Directional body-shielding mass was evaluated for over 1500 target points of MAX for specified organs considered to be sensitive to the induction of stochastic effects. Radiation exposures to solar particle event (SPE), trapped protons, and galactic cosmic ray (GCR) were assessed at the specific sites in the MAX phantom by coupling space radiation transport models with the relevant body-shielding mass. The development of multiple-point body-shielding distributions at each organ made it possible to estimate the mean and variance of organ doses at the specific organ. For the estimate of doses to the blood forming organs (BFOs), data on active marrow distributions in adult were used to weight the bone marrow sites over the human body. The discrete number of target points of MAX organs resulted in a reduced organ dose and dose equivalent compared to the results of CAM organs especially for SPE, and should be further investigated. Differences of effective doses between the two approaches were found to be small (<5%) for GCR. 相似文献
572.
O.E. Ehinlafa O.A. Falaiye J.O. Adeniyi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
This is to investigate ways of improving the Equatorial F2-layer peak heights estimated from M(3000)F2 ionosonde data measured using the Ionospheric Prediction Service (IPS-42) sounder at Ouagadougou, Burkina Faso (Latitude +12.4°N, Longitude +1.5°W, Dip latitude +5.9°N) during a low solar activity year (1995). For this purpose, we have compared the observed hmF2 (hmF2obs) deduced using an algorithm from scaled virtual heights of quiet day ionograms and the predicted hmF2 values which is given by the IRI 2007 model (hmF2IRI 2007) with the ionosonde measured M(3000)F2 estimation of the hmF2 values (hmF2est) respectively. The correlation coefficients R2 for all the seasons were found to range from 0.259 to 0.692 for hmF2obs values, while it ranges from 0.551 to 0.875 for the hmF2IRI 2007 values. During the nighttime, estimated hmF2 (hmF2est) was found to be positively correlated with the hmF2obs values by the post-sunset peak representation which is also represented by the hmF2IRI 2007 values. We also investigated the validity of the hmF2est values by finding the percentage deviations when compared with the hmF2obs and hmF2IRI 2007. 相似文献
573.
Analytical and numerical approaches of a solar array thermal analysis in a low-earth orbit satellite
Hui Kyung Kim Cho Young Han 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
This paper researches the thermal analysis of a fixed-type solar array in a low-earth orbit satellite through both an analytical method with a simplified thermal model and a numerical method with a detailed thermal model. 相似文献
574.
Interplanetary physics study is an important ingredient in space weather research. Considerable progress this aspect has been achieved by the space physics community of China in recent years. This brief report summarizes the latest advances of the interplanetary physics research in China during the period of 2008--2010. This report includes solar corona and solar wind, interplanetary transients, energetic particles, MHD simulation, space plasma, and prediction methods for physical phenomena originating from both solar corona and interplanetary space. 相似文献
575.
利用SOHO/MDI全日面纵向磁图, 计算了三个描述太阳活动区磁场复杂性和非势性的特征物理量, 即纵向磁场最大水平梯度Bz, 强梯度中性线长度L, 孤立奇点数目η. 为检验太阳光球磁场特征在质子事件短期预报中是否有效, 采用BP神经网络方法, 建立了基于这三个磁场特征物理量简单的太阳质子事件短期(24h)预报模型. 模 型在对2002年和2003年连续两年的样本检测中, 有很高的准确率(2002年和2003年 分别为90 %, 87.54 %)和较高的 质子事件报准率(2002年和2003年分别为60 %, 75 %),从而为光球磁场特征物理量作为质子事件预报的有效因子提供了依据. 相似文献
576.
577.
针对卫星在轨太阳辐射热流计算过程中计算参数多,计算过程复杂的问题,提出了一种简化的计算方法。该方法在分析卫星、地球和太阳三者之间空间几何关系的基础上,建立了新的计算坐标系,在计算坐标系中对卫星、地球和太阳的位置进行了重新规定,并在此坐标系中推导了卫星太阳辐射热流的计算公式。运用此方法对卫星太阳辐射热流进行分析求解时,轨道参数之间的空间角度关系更为简单,仅需对7个主要参数进行计算,与传统方法相比较计算量减少了约2/3。 相似文献
578.
基于过渡过程安排的PID控制器设计 总被引:2,自引:0,他引:2
分析了过渡过程安排法对PID控制的影响,提出了一种基于过渡过程安排法的PID控制器设计的新方法。针对航天器太阳电池板热真空试验,搭建温度控制系统,进行物理仿真实验。实验表明,该方法能够实现快速无超调控制,控制器参数选取方便,适应性、鲁棒性得到增强。 相似文献
579.
Removing Solar Radiation Based on the Empirical Mode Decomposition Method for Seismo-Ionospheric Anomaly Before the M9.0 Tohoku Earthquake 下载免费PDF全文
The ionospheric effect from solar activity can be seen as the background in the process of detecting the ionospheric precursor prior to strong earthquakes. The ionospheric variation induced by the forthcoming earthquake can be covered by the strong solar background during the period of high solar activity. The issue of how to remove the ionospheric effect from solar radiation is of outstanding significance. In this paper, a method of Empirical Mode Decomposition (EMD) is used to eliminate the solar background. As a case study, the global ionospheric map TEC before the M9.0 Tohoku earthquake on 11 March 2011 is analyzed. After the effect of solar radiation is removed using the EMD method, the precursor of the imminent earthquake is more obvious. The ionospheric anomaly had a local character and only appeared close to the earthquake epicenter while the useful signals were covered by the solar radiation background with traditional method, which implies that the EMD method is effective in eliminating solar radiation background. 相似文献
580.
针对航天器太阳电池阵电设计和热设计中需要准确考虑阴影影响的问题,提出了一种可以精确计算太阳电池阵阴影的方法。首先使用三角网格来建立3D模型,其次考虑了航天器本体构件间的相对运动,然后用一个“包围盒”去截取模型上的三角网格点,再把这些点投射到太阳电池阵上,最后把太阳电池阵分成小方格,分别使用逐点比较法和最小矩形法来生成阴影图形。给出了月球车遮挡计算的实例,仿真分析表明生成阴影图形时,最小矩形法具有更高的速度。使用本文所述的方法,可计算结构复杂、构件间有相对运动的航天器本体对太阳电池阵造成的遮挡,能生成精确的阴影图形,为后续计算受遮挡的太阳电池阵的输出特性奠定了基础。 相似文献