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341.
本文针对一种新型轴封的润滑机理和工作性能进行了基本理论研究。光学干涉法已成功地用于研究镜面橡胶密封件的液膜剖面。业已发现,在广泛的工况范围内,存在着弹性流体动力润滑效应。对偏置密封件的其他性能参数的研究证明:其有效应用范围界于填料密封和机械密封之间 相似文献
342.
推进剂内部和推进剂—包复层界面的裂纹、气泡和脱粘的 X-射线实时显像检测系统的产生是固体推进剂火箭发动机质量控制的重大突破。在此之前,用成本很高的普通胶片 X-射线照相法进行抽样检验,而且对送检的每台发动机只能沿推进剂—包复层界面切线方向每隔60度或120度作局部 X-射线检查。新方法具有自动地连续100%检验能力,其成本低于普通的胶 相似文献
343.
一九七八年,美国陆军导弹司令部开始进行一项艰巨的研究任务——为未来的导弹发展一种高级制导系统。为了对付具有二十世纪九十年代以及更远时期预计特性的目标,满足当时战场环境所强加的严格要求和约束条件,设想该系统要“远远超越”目前正在研制的各种系统。本文对此课题重新作了详细说明,并且介绍了最新的发展研究规划。同时,还对迄今已经取得的各种成果作了评述,特别是在以下各个方面:目前正用来分析和模拟导弹及其制导系统的各种数学模型;空气动力学;推进系统;正在研究与分析的各种导引规律;扰动调节控制的发展状况;定位与跟踪目标的信号处理和数字化设计方法研究。本文最后一节还列举了得到合同承包者支持的各种未来计划。 相似文献
344.
The working efficiency and state-of-mind of a Space vehicle crew on long-term missions is dependent on the suitability of living conditions including food. Our purpose was to establish the feasibility of an in vitro muscle protein production system (MPPS) for the fabrication of surrogate muscle protein constructs as food products for Space travelers. In the experimental treatments, we cultivated the adult dorsal abdominal skeletal muscle mass of Carassius (Gold fish). An ATCC fish fibroblast cell line was used for tissue engineering investigations. No antibiotics were used during any phase of the research. Our four treatments produced these results: a low contamination rate, self-healing, cell proliferation, a tissue engineered construct of non-homologous co-cultured cells with explants, an increase in tissue size in homologous co-cultures of explants with crude cell mixtures, maintenance of explants in media containing fetal bovine serum substitutes, and harvested explants which resembled fresh fish filets.
We feel that not only have we pointed the way to an innovative, viable means of supplying safe, healthy, nutritious food to Space voyagers on long journeys, but our research also points the way to means of alleviating food supply and safety problems in both the public and private sectors worldwide. 相似文献
345.
Ishizaki Y Ishizaki T Fukuoka H Kim CS Fujita M Maegawa Y Fujioka H Katsura T Suzuki Y Gunji A 《Acta Astronautica》2002,50(7):453-459
This study evaluated changes of mood status and depressive and neurotic levels in nine young male subjects during a 20-day 6 degrees head-down tilting bed rest and examined whether exercise training modified these changes. Participants were asked to complete psychometrical inventories on before, during, and after the bed rest experiment. Depressive and neurotic levels were enhanced during bed rest period according to the Japanese version of Zung's Self-rating Depression Scale and the Japanese version of the General Health Questionnaire. Mood state "vigor" was impaired and "confusion" was increased during bed rest and recumbent control periods compared to pre-bed rest and ambulatory control periods according to the Japanese version of Profiles of Mood State, whereas the mood "tension-anxiety", "depression-dejection", "anger-hostility" and "fatigue" were relatively stable during experiment. Isometric exercise training did not modify these results. Microgravity, along with confinement to bed and isolation from familiar environments, induced impairment of mental status. 相似文献
346.
Macho L Nemeth S Kvetnansky R Fickova M Tigranian RA Serova L 《Acta Astronautica》1982,9(6-7):385-389
The activity of the enzymes involved in aminoacid metabolism (tyrosine aminotransferase, TAT, tryptophan pyrrolase TP, serine dehydratase, SD) with rapid response to glucocorticoids and enzymes requiring for activity increase repeated administration of corticosterone (alanine aminotransferase, ALT, aspartate aminotransferase, AST) in liver, the changes of lipolysis in adipose tissue and the plasma corticosterone levels were studied in rats subjected to space flight (F), in animals from synchron model experiments (SM, simulated conditions of space flight in laboratory) and in intact controls (C). The increase of plasma corticosterone concentration and of the activity of rapidly (TAT, TP, SD) and slowly activating enzymes (ALT, AST) was found in F group 6-10 hr after space flight (18.5 days on biosatellite COSMOS 1129). This suggested the presence of acute-stress (associated primarily with the landing) and chronic stress induced hypercorticosteronemia during the flight. After the short 6-day period of recovery the plasma corticosterone concentrations and the activities of liver enzymes returned to control levels. The exposition of animals to repeated immobilization stress showed higher response of corticosterone levels in flight rats as compared to intact controls. No changes in basal lipolysis were observed in flight rats in comparison to intact controls, however the stimulation of lipolysis by norepinephrine was lower in animals from F and SM groups. This lower response of lipolytic processes to norepinephrine was found in flight animals also after six days period of recovery. These results showed that there are important changes in the regulation of lipolytic processes in adipose tissue of rats after space flight and in the conditions of model experiments. 相似文献
347.
文章详细叙述了具有恒定曲率半径、口径向外扩张的HE_(11)混合模波纹喇叭的设计和特性,以及喇叭馈电所需要的波纹波导模转换器的设计要点。若给定的曲率半径在设计频率f_0处大于波长的1.2倍左右,则交叉极化旁瓣强度随喇叭频率特性而明显变化,且在f_0附近有低于-50dB的极小值。因此,建议在要求极低交叉极化电平的场合下把这种喇叭作为标准喇叭。文中的归一化曲线显示了作为喇叭参数函数的交叉极化、波束宽度和相位中心的位置,当在1.36:1的频带宽度时,并没受到交叉极化性能的限制,而在频带低端边缘附近,受到反射损耗急剧劣化的影响。对于给定的交叉极化电平,其带宽随曲率半径的增大而增加。文中详细讨论了为获得低交叉极化电平而必备的预防措施以及在模转换器设计中的基本原理。 相似文献
348.
349.
20多年来,火箭工程设计人员一直在研究耐高温、抗氧化陶瓷材料的应用可能性,但是这些材料的主要缺点是易碎和抗热壅塞性差.目前工业用碳陶瓷和陶瓷-陶瓷结构复合材料具有很好的弹性和很强的抗热壅塞性能,这重新引起了人们制造高温火箭发动机复合材料部件的兴趣.这类新材料目前正由欧洲动力装备公司(SEP)生产,其名为SEPCARB和CERASEP,它们具有独特的热和机械性能,可以取代难熔金属而应用于可贮存二元推进剂火箭发动机的整体式喷管和推力室.装有这些部件的工艺发动机已经试验成功,从而为下一代火箭发动机的生产铺平了道路. 相似文献
350.
航天计划中将增加原子频标的使用,以获得精确的时间和稳定的频率。GPS系统所具有的卓越的导航功能主要是由系统中采用的原子频标带来的,新一代的军事通信卫星(Mistar)载有我路复合铷原子频标以满足各种通讯才操作上的需要,第一颗军用通讯卫星,DFS-1使用了事和石英晶体振荡器,第二颗军用通讯卫星,1995年发射的DFS-2,是第一颗使用铷原子频标的军用通讯卫星,这以后发射的卫星都作用了铷原子频标。 相似文献