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701.
An overview of the material developments currently being pursued by the European Space Agency (ESA) with respect to X-ray, γ-ray and neutron detection media is given. The benefits underlying the selection of specific materials are discussed. In the X-ray regime the basic microphysics behind degraded spectral performance caused by the polarization effect and Te inclusions, have been investigated. We have found that both effects degrade the spectra by producing a localised distortion of the electric field. The underlying cause for the distortion does however differ. For the γ-ray regime, a low-noise equivalent scintillator to LaBr3 has been developed in the form of CeBr3. Three inch crystals with a FWHM energy resolution of 4.4% at 662 keV have successfully been produced. For neutron detection, a boron compound based solid state neutron detector has been developed that is sensitive to neutrons, alpha particles and 60 keV X-rays. The measured detection efficiency in detection for thermal neutrons was found to be in the order of a few per cent. 相似文献
702.
1700℃热校准风洞 总被引:1,自引:0,他引:1
1700℃热本单位风洞是一台高温、高速的稳态与动态温度校准装置。本文介绍了1700℃热校准风洞的主要性能和特点,以及为此而采取的保温与冷却相结合的结构设计、高温内壳设计和其它的一些技术方法。 相似文献
703.
The Desert Research and Technology Studies (D-RATS) 2011 field test involved the planning and execution of a series of exploration scenarios under operational conditions similar to those expected during a human exploration mission to a near-Earth asteroid (NEA). The focus was on understanding the operations tempo during simulated NEA exploration and the implications of communications latency and limited data bandwidth. Anchoring technologies and sampling techniques were not evaluated due to the immaturity of those technologies and the inability to meaningfully test them at D-RATS. Reduced gravity analogs and simulations are being used to fully evaluate Space Exploration Vehicle (SEV) and extravehicular (EVA) operations and interactions in near-weightlessness at a NEA as part of NASA's integrated analogs program. Hypotheses were tested by planning and performing a series of 1-day simulated exploration excursions comparing test conditions all of which involved a single Deep Space Habitat (DSH) and either 0, 1, or 2 SEVs; 3 or 4 crewmembers; 1 of 2 different communications bandwidths; and a 50-second each-way communications latency between the field site and Houston. Excursions were executed at the Black Point Lava Flow test site with a remote Mission Control Center and Science Support Room at Johnson Space Center (JSC) being operated with 50-second each-way communication latency to the field. Crews were composed of astronauts and professional field geologists. Teams of Mission Operations and Science experts also supported the mission simulations each day. Data were collected separately from the Crew, Mission Operations, and Science teams to assess the test conditions from multiple perspectives. For the operations tested, data indicates practically significant benefits may be realized by including at least one SEV and by including 4 versus 3 crewmembers in the NEA exploration architecture as measured by increased scientific data quality, EVA exploration time, capability assessment ratings, and consensus acceptability ratings provided by Crew, Mission Operations, and Science teams. A combination of text and voice was used to effectively communicate over the communications latency, and increased communication bandwidth yielded a small but practically significant improvement in overall acceptability as rated by the Science team, although the impact of bandwidth on scientific strategic planning and public outreach was not assessed. No effect of increased bandwidth was observed with respect to Crew or Mission Operations team ratings of overall acceptability. 相似文献
704.
给出一种多通道用户界面的三维表示模型,证明目标选择是多通道人机交互技术的核心。针对多通道用户界面中输入信息的不精确性,运用模糊模式识别理论,提出根据不精确输入信息进行的目标选择算法。 相似文献
705.
高职院校学生心理健康问题及解决途径 总被引:1,自引:0,他引:1
盖玉莲 《西安航空技术高等专科学校学报》2009,27(4)
近年来,高职院校学生的心理问题比较突出,但最终解决问题的效果却不尽人意.旨在探讨新时期高职学生心理健康的现状和存在的问题,分析这些问题的成因,提出了设置健全的心理健康教育机构、加强心理教育师资建设、普及心理学知识、开展心理咨询活动、展开校际合作和进行社会实践活动的心理健康教育模式,以达到对高职学生心理健康教育的效果. 相似文献
706.
707.
Elchin S. Babayev Aysel A. Allahverdiyeva 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,40(12):1941-1951
There are collaborative and cross-disciplinary space weather studies in the Azerbaijan National Academy of Sciences conducted with purposes of revealing possible effects of solar, geomagnetic and cosmic ray variability on certain technological, biological and ecological systems. This paper describes some results of the experimental studies of influence of the periodical and aperiodical changes of geomagnetic activity upon human brain, human health and psycho-emotional state. It also covers the conclusions of studies on influence of violent solar events and severe geomagnetic storms of the solar cycle 23 on the mentioned systems in middle-latitude location. It is experimentally established that weak and moderate geomagnetic storms do not cause significant changes in the brain’s bioelectrical activity and exert only stimulating influence while severe disturbances of geomagnetic conditions cause negative influence, seriously disintegrate brain’s functionality, activate braking processes and amplify the negative emotional background of an individual. It is concluded that geomagnetic disturbances affect mainly emotional and vegetative spheres of human beings while characteristics reflecting personality properties do not undergo significant changes. 相似文献
708.
本文使用状态转移矩阵与积分型级数解表达式,推出了线性时变系统外干扰完全补偿原理表达式,此式简单、精确,便于终端关机方程使用,文中并给出了一组初值t_p,Ψ可变动的伴随函数解析解表达式。 相似文献
709.
从1787年美国宪法制定至今已有200多年,这部牛车时代制定的不过8000字的宪法修改很少,却能够适应逐步形成的现代工业社会的需要,主要原因是宪法中的某些重要措辞如“贸易条款”、“必要与适当”、“正当程序”及“诚实信用”等极富弹性。美国宪法第1和第8款第3项的“贸易条款”最集中地体现了它的价值。因此,了解美国宪法中的“贸易条款”对于认识美国宪法和法律具有重要意义。 相似文献
710.
针对2A12-T4铝合金薄板类零件在加工过程中,采用110℃保温6小时去应力处理后,对材料硬度略有升高的现象进行了不同参数的工艺试验,试验结果表明在240℃~260℃范围内加热4~6小时的去应力处理,既可降低材料硬度HRB4~7,又能满足设计要求的强度指标,对降低零件机械加工切削力、减小零件残余应力是十分有利的。 相似文献