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61.
NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g/cm2 in mass thickness and have predicted that shields of this mass thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the Earth's atmosphere, a very thick, i.e. high mass, shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus. 相似文献
62.
S.A. Washburn S.R. Blattnig R.C. Singleterry S.C. Westover 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The use of active radiation shielding designs has the potential to reduce the radiation exposure received by astronauts on deep-space missions at a significantly lower mass penalty than designs utilizing only passive shielding. Unfortunately, the determination of the radiation exposure inside these shielded environments often involves lengthy and computationally intensive Monte Carlo analysis. In order to evaluate the large trade space of design parameters associated with a magnetic radiation shield design, an analytical model was developed for the determination of flux inside a solenoid magnetic field due to the Galactic Cosmic Radiation (GCR) radiation environment. This analytical model was then coupled with NASA’s radiation transport code, HZETRN, to account for the effects of passive/structural shielding mass. The resulting model can rapidly obtain results for a given configuration and can therefore be used to analyze an entire trade space of potential variables in less time than is required for even a single Monte Carlo run. Analyzing this trade space for a solenoid magnetic shield design indicates that active shield bending powers greater than ∼15 Tm and passive/structural shielding thicknesses greater than 40 g/cm2 have a limited impact on reducing dose equivalent values. Also, it is shown that higher magnetic field strengths are more effective than thicker magnetic fields at reducing dose equivalent. 相似文献
63.
64.
Soybean cultivar selection for Bioregenerative Life Support Systems (BLSSs) – Hydroponic cultivation
R. Paradiso R. Buonomo V. De Micco G. Aronne M. Palermo G. Barbieri S. De Pascale 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Four soybean cultivars (‘Atlantic’, ‘Cresir’, ‘Pr91m10’ and ‘Regir’), selected through a theoretical procedure as suitable for cultivation in BLSS, were evaluated in terms of growth and production. Germination percentage and Mean Germination Time (MGT) were measured. Plants were cultivated in a growth chamber equipped with a recirculating hydroponic system (Nutrient Film Technique). Cultivation was performed under controlled environmental conditions (12 h photoperiod, light intensity 350 μmol m−2 s−1, temperature regime 26/20 °C light/dark, relative humidity 65–75%). Fertigation was performed with a standard Hoagland solution, modified for soybean specific requirements, and EC and pH were kept at 2.0 dS m−1 and 5.5 respectively. 相似文献
65.
66.
基于双响应波段工作的红外热像仪测温原理与误差分析 总被引:1,自引:0,他引:1
为了提高红外热像仪测温的准确性,根据红外辐射理论,从红外热像仪的测温原理出发,分析了基于双响应工作波段的热像仪的测温原理,得出了目标物体的发射率、物体温度计算公式以及相应误差的估算公式,分析了各影响因素对热像仪测量准确度的影响,提供了一种目标物体发射率的测定方法,对利用红外热像仪准确测量内燃机等热能机械表面温度具有重要的意义。 相似文献
67.
68.
Evaluation of a combined electrostatic and magnetostatic configuration for active space-radiation shielding 总被引:1,自引:0,他引:1
Ravindra P. Joshi Hao Qiu Ram K. Tripathi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Developing successful and optimal solutions to mitigating the hazards of severe space radiation in deep space long duration missions is critical for the success of deep-space explorations. A recent report (Tripathi et al., 2008) had explored the feasibility of using electrostatic shielding. Here, we continue to extend the electrostatic shielding strategy and examine a hybrid configuration that utilizes both electrostatic and magnetostatic fields. The main advantages of this system are shown to be: (i) a much better shielding and repulsion of incident ions from both solar particle events (SPE) and galactic cosmic rays (GCR), (ii) reductions in the power requirement for re-charging the electrostatic sub-system, and (iii) low requirements of the magnetic fields that are well below the thresholds set for health and safety for long-term exposures. Furthermore, our results show transmission levels reduced to levels as low as 30% for energies around 1000 MeV, and near total elimination of SPE radiation by these hybrid configurations. It is also shown that the power needed to replenish the electrostatic charges due to particle hits from the GCR and SPE radiation is minimal. 相似文献
69.
K. Clark J. Boldt R. Greeley K. Hand I. Jun R. Lock R. Pappalardo T. Van Houten T. Yan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander. 相似文献
70.
在烘烤过程中,密集烤房内部不同位点的风速之间密切又复杂.为确定风速指标间的关系,测定了密集烤房内405个风速值,对15个风速指标进行了灰色关联聚类分析.结果表明:当聚类临界值为0.8时,15个风速指标可被聚为2类;当聚类临界值为0.7时,15个风速指标可被聚为1类.通过分析,密集烤房内部同一平面不同位点的风速差异较小,可视为均匀一致,密集烤房能够保证装烟室同一层烟叶整体上均处于同样的变色和干燥环境下,从而能够在理论上保证其烟叶相同的烘烤质量. 相似文献