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91.
俞渭良  张振利  童京富 《上海航天》1997,14(3):3-7,,11,
详细介绍了××改型导弹折叠舵研究课题的成果。内容包括:主要设计要求、研制程序、方案的拟定、设计、试验及结果分析、结论等部分。通过试制及试验,证明把高强度扭力杆应用于折叠舵的展开机构具有展开能量大、展开时间短、重量轻、体积小、结构简单等优点。该项技术不但使××改型导弹折叠舵课题获得成功,而且可以推广应用到需要折叠与展开的其他飞行器上  相似文献   
92.
本文针对目前战术导弹广泛使用捷联系统这个现状,以及对大机动飞行器采用姿态角误差反馈进行控制有时出现的奇异问题,提出并研究了基于四元数进行大机动战术导弹姿态控制系统的设计问题.首先,给出了大机动飞行情况下基于四元数描述的弹体动力学模型,然后,基于非线性控制系统综合方法设计了姿态控制系统,并验证了系统的稳定性.研究结果表明,基于四元数进行姿态控制系统的设计,既解决了姿态角表示法存在的奇异性问题,又可减少捷联计算机的计算量,对战术导弹具有重要实际意义.最后,通过数值仿真验证了本文提出方法的有效性.  相似文献   
93.
Several studies in animals over the past decade have shown that prolonged exposures to pressures within the range 226 mm Hg to 160 mm Hg (30,000 to 37,500 ft) are likely to lead to brain damage. This often results in neurological and behavioural disturbance, which may be subtle and reversible or gross and ultimately fatal. The appearance of these impairments is often delayed until several hours or even days after exposure. Immediate survival does not necessarily ensure recovery. In contrast, decompression to pressures below 160 mm Hg or above 226 mm Hg are unlikely to have adverse effects if the exposure is survived. The most probable outcomes of such decompressions are death or uneventful recovery.  相似文献   
94.
Several observations indicate that the cloud deck of the venusian atmosphere may provide a plausible refuge for microbial life. Having originated in a hot proto-ocean or been brought in by meteorites from Earth (or Mars), early life on Venus could have adapted to a dry, acidic atmospheric niche as the warming planet lost its oceans. The greatest obstacle for the survival of any organism in this niche may be high doses of ultraviolet (UV) radiation. Here we make the argument that such an organism may utilize sulfur allotropes present in the venusian atmosphere, particularly S(8), as a UV sunscreen, as an energy-converting pigment, or as a means for converting UV light to lower frequencies that can be used for photosynthesis. Thus, life could exist today in the clouds of Venus.  相似文献   
95.
扩展旋转矢量捷联姿态算法   总被引:1,自引:0,他引:1  
周江华  苗育红  肖刚 《宇航学报》2003,24(4):414-417
给出了一种新的旋转矢量捷联姿态构造算法,该算法由陀螺样本的多重积分来构造旋转矢量的最小二乘估计。新算法具有较好的顺序递推结构,易于在机载计算机上编程实现,比传统方法更容易满足一些限制较多的特殊应用。文中还给出了该算法在机载计算机上的计算流程及算法的局部硬件化实现。  相似文献   
96.
The gravitational interaction between the Sun and the planetary solar system gives rise to the well-known tidal waves at the planets. The tidal wave originating in the Earth's crust perpetually transforms the microstructure of the Earth's crust leading to a variation of the concentration of natural radioactive gases in the terrestrial air and to changed conditions of their leakage to the Earth's atmosphere. These variations give rise to bursts of thermal and slow neutrons in the vicinity of the Earth's crust, because the radioactive gases are sources of energetic alpha particles that induce neutron production upon the interaction with the nuclei of elements of the Earth's crust and atmosphere. In this work, the idea of neutron production in the ground coat is extended to the other celestial bodies interacting with one another.  相似文献   
97.
The dynamics of the proton energy spectrum during the solar cycle is studied. The spectra were determined by 1–100 MeV particle fluxes measured by different instruments mounted aboard the Earth's IMP-8 satellite for more than one hundred quiet-time intervals in the period between 1974 and 1991. The galactic branch of the spectra (E p > 10 MeV) constructed for every quiet interval was fitted by a power law function, J =CE . The theory predicts that in the 1–100 MeV energy range, where the adiabatic cooling of particles is dominant, = 1, while we have derived a double-peak distribution. The main maximum has the mean value = 1.35. The mean value of the second, much weaker maximum, is = 0.95. Within the main maximum, values are distributed in accordance with the Gaussian law with a standard deviation D/ = 0.12. The substantial difference of from unity requires the elaboration of a new model of modulation processes in the inner heliosphere. The values corresponding to the second maximum show that modulation processes correspond sometimes to theoretical conceptions. It is shown that correlates weakly with parameters A and describing the solar branch of the spectrum (J(E) = AE ). At the same time, a more significant correlation is observed between and the solar activity index, R z, the counting rate of the Deep River neutron monitor, and the energy value in the minimum of the energy spectrum flux, E min.  相似文献   
98.
The possibility of using the mode of single-axis solar orientation is considered for a satellite placed into a nearly circular orbit with an altitude of 900 km and bearing a solar sail. The satellite (together with the sail) has an axisymmetric structure, its symmetry axis being the principal central axis of the maximum moment of inertia. The center of the sail pressure lies on this axis and is displaced with respect to the satellite's center of mass. The symmetry axis of the satellite is set to the Sun so that its center of mass would be located between the Sun and the pressure center and would rotate around this axis with an angular velocity of a few degrees per second. The satellite's axis of symmetry makes a slow precession under the action of the gravitational moment and the moment of light pressure forces. Though the maximum magnitudes of these moments are comparable, the moment of the light pressure forces dominates and controls the precession in such a way that the symmetry axis orientation to the Sun remains unchanged.  相似文献   
99.
Bacterial spores have been used as model systems for studying the theory of interplanetary transport of life by natural processes such as asteroidal or cometary impacts (i.e., lithopanspermia). Because current spallation theory predicts that near-surface rocks are ideal candidates for planetary ejection and surface basalts are widely distributed throughout the rocky planets, we isolated spore-forming bacteria from the interior of near-subsurface basalt rocks collected in the Sonoran desert near Tucson, Arizona. Spores were found to inhabit basalt at very low concentrations (相似文献   
100.
During previous long-term manned missions, more than 100 species of microorganisms have been identified on surfaces of materials (bacteria and fungi). Among them were potentially pathogenic ones (saprophytes) which are capable of active growth on artificial substrates, as well as technophilic bacteria and fungi causing damages (destruction and degradation) to various materials (metals and polymers), resulting in failures and disruptions in the functioning of equipment and hardware.

Aboard a space vehicle some microclimatic parameters are optimal for microorganism growth: the atmospheric fluid condensate with its specific composition, chemical and/or antropogenic contaminants (human metobolic products, etc.) all are stimulating factors for the development of bacteria and mould fungi on materials of the interior and equipment of an orbital station during its operational phase(s).

Especially Russian long-term missions (SALJUT, MIR) have demonstrated that uncontrolled interactions of microorganisms with materials will ultimately lead to the appearence of technological and medical risks, significantly influencing safety and reliability characteristics of individual as well as whole systems and/ or subsystems.

For a first conclusion, it could be summarized, that countermeasures and anti-strategies focussing on Microbial Contamination Management (MCM) for the International Space Station (ISS, next long-term manned mission) at least require a new materials test approach.

Our respective concept includes a combined age-ing/biocorrosion test sequence. It is represented here, as well as current status of MCM program, e.g. continuous monitoring (microbiological analyses), long-term disinfection, frequent cleaning methods, mathematical modeling of ISS, etc.  相似文献   

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