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941.
A technological process of removing a complex-shaped ceramic core from the interior of GTE thin-walled blade castings is considered. We propose an aluminium oxide-based method for removing a core by leaching accompanied by process intensification with a carboxylic acid additive. 相似文献
942.
S. A. Danilova 《Russian Aeronautics (Iz VUZ)》2007,50(3):344-348
A problem on dynamic determination of a time interval in scheduling aperiodic requests in real-time systems is considered. It is shown that the application of a combined approach based on the combination of the probability method and the method of fuzzy sets provides an effective problem solution. 相似文献
943.
A. B. Shigapov 《Russian Aeronautics (Iz VUZ)》2007,50(4):450-454
Based on the data on composition and calorific power of diesel fuel and solar oil, the conditional expressions of fuels and values of their enthalpies are considered. The data on thermodynamic properties of combustion products are obtained and generalized by calculating the process of air-fuel mixture combustion in a wide range of parameter variations. 相似文献
944.
O. N. Naumov 《Russian Aeronautics (Iz VUZ)》2012,55(2):164-169
The results of the statistical analysis for the rotational motion of a light descent capsule under deployment of the orbital cable system are presented. At mathematical simulation a cable is considered to be a weightless inextensible mechanical linkage. The cable is deployed according to the predetermined law. The basic spacecraft is oriented along the local geovertical by means of its own stabilization system. The simulation is carried out by the statistical testing method. The motion characteristics being studied include: modulus of the capsule angular velocity and the nutation angle at the final point of the cable deployment. 相似文献
945.
Non-standard situation on a spacecraft (Earth’s satellite) is considered, when there are no measurements of the spacecraft’s angular velocity component relative to one of its body axes. Angular velocity measurements are used in controlling spacecraft’s attitude motion by means of flywheels. The arising problem is to study the operation of standard control algorithms in the absence of some necessary measurements. In this work this problem is solved for the algorithm ensuring the damping of spacecraft’s angular velocity. Such a damping is shown to be possible not for all initial conditions of motion. In the general case one of two possible final modes is realized, each described by stable steady-state solutions of the equations of motion. In one of them, the spacecraft’s angular velocity component relative to the axis, for which the measurements are absent, is nonzero. The estimates of the regions of attraction are obtained for these steady-state solutions by numerical calculations. A simple technique is suggested that allows one to eliminate the initial conditions of the angular velocity damping mode from the attraction region of an undesirable solution. Several realizations of this mode that have taken place are reconstructed. This reconstruction was carried out using approximations of telemetry values of the angular velocity components and the total angular momentum of flywheels, obtained at the non-standard situation, by solutions of the equations of spacecraft’s rotational motion. 相似文献
946.
N Munakata K Makita D Bolsee D Gillotay G Horneck 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2000,26(12):1995-2003
Environmental UV radiation can be quantified using spore dosimetry, which measures the inactivation of repair-deficient Bacillus subtilis spores dried on a membrane filter. The system exhibits highly selective sensitivity to UV radiation, not being affected by various environmental adversities, such as high and low temperature and humidity. Biologically-effective dose rate and cumulative dose of ambient radiation are measurable under various conditions at various places on the earth, including tropical, temperate, and polar sites. Applications to monitor the exposure at the surface of organisms including humans and plants have also been advanced. 相似文献
947.
The spatial motion relative to the center of mass is considered for a capsule on an elastic tether, when it is unrolled from
a spacecraft by a special program. The spacecraft is in a circular orbit and oriented relative to the local vertical, which
is guaranteed by operation of its own stabilization system. Angular motion of the capsule relative to the tether direction
is studied, and the main factors influencing the stability of this motion are analyzed. An approximate quasi-linear mathematical
model of the capsule attitude motion is obtained, which allows one to estimate the influence of major disturbances of its
motion. The results of numerical simulations are presented for characteristic cases of the capsule motion. 相似文献
948.
Altitude—temporal cross-sections q(z, t) of atmospheric ionization rates by solar protons above the polar regions were calculated using the GOES-10 satellite data on solar proton fluxes for the period of solar proton flare (SPF) on July 14, 2000. The values of q(z, t) were used further in calculations of variations of the atmospheric chemical composition during the flare in the northern
and southern polar regions (70°N and 70°S) by two different 1D photochemical models of the atmosphere (neutral and charged
components). The calculation results have shown considerable variation of the ozone content after SPF: a decrease of [O3]
was about 80% at altitudes of 65–75 km above northern and 25% in the layer of 55–65 km above the southern polar region. Such
decrease of the ozone content is a result of reactions with [NO] and [OH] whose concentrations have grown substantially during
SPF. According to calculations, the increase of electron concentration during SPF has reached 3–4 orders of magnitude at altitudes
of 50–80 km. A comparison of the calculation results with the observational data on [NO], [NO2], and [O3] from the UARS and HALOE satellites for 70°N have shown a good qualitative correspondence, however, for variations of nitric oxides there are quantitative
discrepancies. 相似文献
949.
B. B. Kreisman 《Cosmic Research》2012,50(1):65-75
Within the framework of the circular restricted three-body problem a family of inverse periodic orbits around the two attracting
bodies (the Egorov’s family) and families generated by it at the 1:1, 2:1, and 3:1 resonances for three-dimensional orbits
in the Sun-Earth and Earth-Moon systems are considered. Their relationship with families generated by orbits around the libration
points L
1, L
2 and L
3 is investigated. One of the families contains periodic solutions that seem promising as possible orbits for the space radio
telescope of the Millimetron project. 相似文献
950.
A system for recording and analysis of flight information including the technical condition of a control object and the state of its controller’s health in real time aboard a flight vehicle and in ground-based air traffic control centers is described. 相似文献