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921.
An effect of the Coriolis forces on the process of gas expansion in the turbine stage is considered. Expressions for efficiency with regard for the radial flow passage are derived. The calculation results and statistical data on the geometric parameters of diagonal stages are presented. 相似文献
922.
N. A. Gureeva 《Russian Aeronautics (Iz VUZ)》2009,52(2):138-144
In the framework of a plane problem of elasticity theory in strength analysis based on the finite element method in the hybrid formulation, we suggest that the approximation of displacements and stresses be used as magnitudes of vector and tensor fields, respectively. The quadrilateral finite element, the displacements and stresses of which are accepted as nodal unknowns is proposed. The mixed Reissner functional is applied to form a finite element deformation matrix. 相似文献
923.
The unsteady aerodynamic loads (pressure increment and generalized forces) acting on a deformable thin airfoil section are determined for its arbitrary motion in the incompressible flow with transverse gusts. In this case, the exact Küssner solution in series is used for harmonic oscillation of an airfoil, in which the Theodorsen function is approximated by a sum of fractional functions with poles. In the time domain, these functions are replaced by the unknown functions that satisfy the one-type ordinary first order differential equations. The equations obtained are combined with the differential equations of the airfoil motion in the generalized coordinates and are used for analyzing the aeroelastic system stability and calculating its dynamic response to gust loads. 相似文献
924.
V. A. Arkhipov 《Russian Aeronautics (Iz VUZ)》2009,52(1):83-87
An approach and algorithms are proposed that make it possible to take into account an effect of magnetic interferences introduced by a mobile object, variation of its inclination angles and, hence, to improve precision of the magneto-inertial horizon-compass operation. 相似文献
925.
S. Gadimova H.J. Haubold 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,43(12):1863-1865
Based on resolutions of the United Nations General Assembly, Regional Centres for Space Science and Technology Education were established in India, Morocco, Nigeria, Brazil and Mexico. Simultaneously, education curricula were developed for the core disciplines of remote sensing, satellite communications, satellite meteorology, and space and atmospheric science. This paper provides a brief summary on the status of the operation of the regional centres with a view to use them as information centres of the International Committee on Global Navigation Satellite Systems (ICG), and draws attention to their educational activities. 相似文献
926.
Based on the archive OMNI data for the period 1976–2000 an analysis has been made of 798 geomagnetic storms with D
st
< −50 nT and their interplanetary sources-large-scale types of the solar wind: CIR (145 magnetic storms), Sheath (96), magnetic
clouds MC (62), and Ejecta (161). The remaining 334 magnetic storms have no well-defined sources. For the analysis, we applied
the double method of superposed epoch analysis in which the instants of the magnetic storm beginning and minimum of D
st
index are taken as reference times. The well-known fact that, independent of the interplanetary source type, the magnetic
storm begins in 1–2 h after a southward turn of the IMF (B
z
< 0) and both the end of the main phase of a storm and the beginning of its recovery phase are observed in 1–2 h after disappearance
of the southward component of the IMF is confirmed. Also confirmed is the result obtained previously that the most efficient
generation of magnetic storms is observed for Sheath before MC. On the average parameters B
z
and E
y
slightly vary between the beginning and end of the main phase of storms (minimum of D
st
and D
st
* indices), while D
st
and D
st
* indices decrease monotonically proportionally to integral of B
z
and E
y
over time. Such a behavior of the indices indicates that the used double method of superposed epoch analysis can be successfully
applied in order to study dynamics of the parameters on the main phase of magnetic storms having different duration. 相似文献
927.
928.
P Sonnentrucker B H Foing P Ehrenfreund 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,24(4):519-522
We present a study of the behaviour and ionization properties of four Diffuse Interstellar Bands (DIBs) at lambda lambda 5780, 5797, 6379 and 6613 angstroms. In the lambda lambda 5797, 6379 and 6613 angstrom DIBs, substructures have recently been detected, indicating large gaseous molecular carriers. Studying DIBs in regions with different physical properties in terms of UV flux and density enables us to monitor the behaviour of the carriers and hence to constrain their nature. As a follow-up of Sonnentrucker et al. (1997), we add new lines of sight and generalize the results for lines of sight with 2 or 3 clouds. This refines the Ionization Potential estimates which are between 10 and 13 eV, hence reminiscent of PAH or fullerene cations for those DIBs. 相似文献
929.
V. A. Gladyshev A. Yu. Shchekotov N. V. Yagova J. -J. Berthelier M. Parrot O. S. Akent’eva L. N. Baranskii E. N. Fedorov T. M. Mulyarchik O. A. Molchanov 《Cosmic Research》2012,50(2):103-115
Variations in concentration of ions H+, He+, and O+ are studied at a height of about 700 km using the data of continuous observations onboard the DEMETER satellite at the decline and in the minimum of solar activity from 2004 to 2008. Latitudinal distributions, seasonal behavior,
and irregular variations in ion concentrations and their dependence on solar and geomagnetic activity are considered. Within
this altitude range, for the first time an analysis is performed of the dataset of many-year continuous observations in both
hemispheres from the equatorial to subauroral latitudes. This made it possible to describe the seasonal and irregular variations
of the concentrations of main ion species with better time and spatial resolution than in the available empirical models.
The dependence of concentrations of three types of ions on solar and geomagnetic activity is studied at time scales from several
days to several years, and it is shown that the anti-phase change in concentrations of O+ and light ions known from publications is partly a result of mutual dependence of solar and geomagnetic activity and is observed
only at time scales beginning from several months. At time scales from several days to several weeks, variations in the concentration
of O+ and light ions are governed mainly by solar and geomagnetic activity, respectively. 相似文献
930.
O. B. Barysheva 《Russian Aeronautics (Iz VUZ)》2007,50(4):374-379
The behavior of generalized diffusion coefficients and diffusion flows of individual substances in the multicomponent gas mixture is investigated. The combustion products of liquid rocket propellants being used are considered. 相似文献