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961.
从教育生态学的角度来看,英语阅读课的教学是在一个由多种因子构成的生态环境中进行的。按照能否在教学过程中得到控制或调整,本文将这些因子分成可控和不可控两大类,并分析了对于阅读教学影响较大的几种可控因子,包括学习氛围、学校的设施、阅读动机和学习策略等。对这些因子的干预能够改善教学生态环境,提高学生英语阅读的效率。 相似文献
962.
雨雾环境下温度传感器动态特性测试方法 总被引:1,自引:0,他引:1
针对雨雾环境下温度传感器的动态特性测试,对常规测试装置进行了改进,研究了雨雾环境的产生和控制方法,并提出了雨雾环境下传感器动态特性的试验方法,在此基础上对某传感器进行了试验,得到了其常规环境和雨雾环境下的动态特性试验结果,试验结果表明雨雾环境下传感器的动态特性会大幅提高;最后,对试验结果和试验中存在的问题进行了分析,明确了试验方法的改进方向。 相似文献
963.
K. Fayazbakhsh A. Abedian 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Application of the existing materials selection methods is not much popular in space environment. This is in spite of involvement of the selection process in this field with a wide range of influential factors (e.g. conventional mechanical properties and over 21 space environmental effects). In this paper an introductory road map for employing systematic materials selection methods in the field by engaging the selection process with mechanical properties and only one of the space environmental factors is presented. Here, selected case studies, which are involved with outgassing phenomenon of materials in vacuum condition, highlight the incapability of some of the methods in dealing with such example problems. The study specifically indicates the effectiveness of the most recently introduced method, i.e. Z-transformation, over other existing methods. The results show that considering the mechanical properties of materials in conjunction with the space environmental effects produce much more reliable ranking of the candidate materials. Besides, the results recommend introducing more space environmental aspects in the selection process may produce a better outcome. 相似文献
964.
Erika M. Harnett Robert M. Winglee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The Moon spends 20% of its orbit within the terrestrial magnetosphere. During this time it experiences a dynamic plasma environment, including high-speed streams, flux ropes and a flux of heavy ions from ionospheric outflows. 3D multi-fluid simulations of the Moon within the magnetosphere during a substorm shows that a highly variable plasma flow can develop in the vicinity of the Moon due to the passage of a flux rope. The transit of a flux rope past the Moon potentially leads to a plasma wake that is mis-aligned from the optical wake by nearly 30°. This will have implications when determining the range of space weathering and surface charging the lunar surface experiences. 相似文献
965.
966.
Orbital debris environment models are essential in predicting the characteristics of the entire debris environment, especially for altitude and size regimes where measurement data is sparse. Most models are also used to assess mission collision risk. The IDES (Integrated Debris Evolution Suite) simulation model has recently been upgraded by including a new sodium–potassium liquid coolant droplet source model and a new historical launch database. These and other features of IDES are described in detail. The accuracy of the IDES model is evaluated over a wide range of debris sizes by comparing model predictions to three major types of debris measurement data in low Earth orbit. For the large-size debris population, the model is compared with the spatial density distribution of the United States (US) Space Command Catalog. A radar simulation model is employed to predict the detection rates of mid-size debris in the field of view of the US Haystack radar. Finally, the small-size impact flux relative to a surface of the retrieved Long Duration Exposure Facility (LDEF) spacecraft is predicted. At sub-millimetre sizes, the model currently under-predicts the debris environment encountered at low altitudes by approximately an order of magnitude. This is because other small-size debris sources, such as paint flakes have not yet been characterised. Due to the model enhancements, IDES exhibits good accuracy when predicting the debris environment at decimetre and centimetre sizes. Therefore, the validated initial conditions and the high fidelity future traffic model enables IDES to make long-term debris environment projections with more confidence. 相似文献
967.
968.
为保证飞机座舱环境和设备舱电子设备正常工作,现代飞机大都采用高压除水空气循环制冷系统进行环境控制,针对系统出口温度这一重要参数,在给定条件下,通过定性、定量相结合的分析方法,推导出了飞机环境控制系统出口温度的计算公式,找出了系统出口温度与水分离器出口温度及涡轮膨胀比的关系,并对误差进行了分析,给出了修正方法,对飞机环境控制系统设计计算具有指导作用。 相似文献
969.
航空发动机地面模拟吞水试验 总被引:3,自引:1,他引:3
马庆祥 《燃气涡轮试验与研究》2002,15(4):39-44
介绍了航空发动机地面模拟吞水试验的试验目的、试验设备、大气中的雨水状况;提出了军、民用发动机的吞水试验要求;分析了试验选用的雨滴直径;计算了试验用水量。 相似文献