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991.
992.
概述了CVD—Si3N4陶瓷及其复合材料在干燥氧气下的氧化行为。Si3N4陶瓷在高温下氧化时,除生成SiO2保护膜外,还生成一薄层比SiO2膜更优异的氧气扩散阻挡层(Si—O—N化合物层),该层具有优异的抗氧化性能。介绍了两种氧化机制模型,同时分析了温度、杂质等对CVD—Si3N4陶瓷氧化行为的影响。 相似文献
993.
994.
A. Antoniou E. Danezis E. Lyratzi L.Č. Popović D. Stathopoulos M.S. Dimitrijević 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
In this paper, using the Gauss-Rotation model (GR model), we analyse the UV C IV resonance lines in the spectra of 20 Oe-stars of different spectral subtypes, in order to detect the structure of C IV region. We study the presence and behavior of absorption clouds and analyse their characteristics. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, the Full Width at Half Maximum (FWHM), the optical depth, as well as the absorbed energy and the column density of the independent regions of matter, which produce the main and the satellite clouds of the studied spectral lines. Finally, we present the relations between these physical parameters and the spectral subtypes of the studied stars and we give our results about the structure of the C IV region in their atmosphere. 相似文献
995.
S Silverstone M Nelson A Alling J P Allen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(9):1544-1551
During the years 2002 and 2003, three closed system experiments were carried out in the \"Laboratory Biosphere\" facility located in Santa Fe, New Mexico. The program involved experimentation of \"Hoyt\" Soy Beans, (experiment #1) USU Apogee Wheat (experiment #2) and TU-82-155 sweet potato (experiment #3) using a 5.37 m2 soil planting bed which was 30 cm deep. The soil texture, 40% clay, 31% sand and 28% silt (a clay loam), was collected from an organic farm in New Mexico to avoid chemical residues. Soil management practices involved minimal tillage, mulching, returning crop residues to the soil after each experiment and increasing soil biota by introducing worms, soil bacteria and mycorrhizae fungi. High soil pH of the original soil appeared to be a factor affecting the first two experiments. Hence, between experiments #2 and #3, the top 15 cm of the soil was amended using a mix of peat moss, green sand, humates and pumice to improve soil texture, lower soil pH and increase nutrient availability. This resulted in lowering the initial pH of 8.0-6.7 at the start of experiment #3. At the end of the experiment, the pH was 7.6. Soil nitrogen and phosphorus has been adequate, but some chlorosis was evident in the first two experiments. Aphid infestation was the only crop pest problem during the three experiments and was handled using an introduction of Hyppodamia convergens. Experimentation showed there were environmental differences even in this 1200 cubic foot ecological system facility, such as temperature and humidity gradients because of ventilation and airflow patterns which resulted in consequent variations in plant growth and yield. Additional humidifiers were added to counteract low humidity and helped optimize conditions for the sweet potato experiment. The experience and information gained from these experiments are being applied to the future design of the Mars On Earth(R) facility (Silverstone et al., Development and research program for a soil-based bioregenerative agriculture system to feed a four person crew at a Mars base, Advances in Space Research 31(1) (2003) 69-75; Allen and Alling, The design approach for Mars On Earth(R), a biospheric closed system testing facility for long-term space habitation, American Institute of Aeronautics and Astronautics Inc., IAC-02-IAA.8.2.02, 2002). 相似文献
996.
In the framework of the general theory for unsteady weakly disturbed fluid flows with free boundaries, a problem is solved to calculate a jet flow around the cascade of plates executing the harmonic oscillations. We developed a program that enables us for the first time to carry out systematic calculations of flow characteristics depending on arbitrary values of determining parameters. 相似文献
997.
以气氢/气氧为推进剂,对圆转方内喷管单元直排塞式喷管进行了热试实验研究。介绍了实验系统及实验发动机主要零部件的结构和设计参数,给出了实验参数测量结果、实验照片和数据分析。无再生冷却塞式喷管发动机采用耐烧蚀材料钨渗铜加工内喷管和燃烧室内衬,碳钢材料加工塞锥,成功进行了多次短时间热试实验。在三个压比下获得了塞式喷管性能数据,实验表明,塞式喷管具有良好的高度补偿能力和较高的效率。在CNPR=110附近,效率达到93%~95%;在CNPR=450附近,效率达到96%~98%;在CNPR=1000附近,效率达到93%~96%。预计在设计点的效率不低于98%。 相似文献
998.
999.
Y12─Ⅱ型飞机结冰对其飞行特性影响的试飞研究 总被引：1，自引：0，他引：1
以Ｙ１２─Ⅱ型飞机防冰系统适航验证试飞为例，就确定飞机结冰部位与防护方法，结冰对飞机飞行性能和操稳特性的影响，带冰着陆的可能性及其安全措施等问题进行了分析和讨论。通过飞行试验，初步检查出飞机结冰造成飞机飞行性能的损失和操稳特性的降低。仅在新机研制中，为防冰系统适航性验证工作提供参考。 相似文献
1000.