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881.
A. I. Golovanov 《Russian Aeronautics (Iz VUZ)》2010,53(2):161-166
A technique for numerical finite element analysis of large elastoplastic strains is proposed. A problem is formulated in terms
of principal stretches and their logarithms in the current basis of the left distortion tensor. It is shown that the “classical”
multiplicative decomposition of the total strain gradient into the product of elastic and plastic strain gradients is equivalent
to the presentation of total stretches as a product of elastic and plastic stretches. 相似文献
882.
We reveal a functional diagram, design features of a receiver electrode system, a principle of forming primary informative
signals, a technique for synthesizing angular characteristics and estimating indicated errors, channel realization and algorithms
of forming output signals of an ionmarking aerodynamic angle and airspeed sensor with logometric informative signals and interpolation
processing scheme. 相似文献
883.
Using the results of numerical modeling of nonstationary gas hydrodynamic working processes in the gas conduit variable section
channel when removing and cooling hot gases of different purpose technical plants, an engineering technique has been developed
to provide the gas conduit operation under limitations on the flow temperature in the outlet plant section. A multiparametric
area of permissible gas conduit operation connecting the characteristics of technical plants, gas conduit and water feeding
system is presented. 相似文献
884.
A. T. Y. Lui 《Space Science Reviews》2011,158(1):43-68
Electric currents permeate space plasmas and often have a significant component along the magnetic field to form magnetic
flux ropes. A larger spatial perspective of these structures than from the direct observation along the satellite path is
crucial in visualizing their role in plasma dynamics. For magnetic flux ropes that are approximately two-dimensional equilibrium
structures on a certain plane, Grad-Shafranov reconstruction technique, developed by Bengt Sonnerup and his colleagues (see
Sonnerup et al. in J. Geophys. Res. 111:A09204, 2006), can be used to reveal two-dimensional maps of associated plasma and field parameters. This review gives a brief account
of the technique and its application to magnetic flux ropes near the Earth’s magnetopause, in the solar wind, and in the magnetotail.
From this brief survey, the ranges of the total field-aligned current and the total magnetic flux content for these magnetic
flux ropes are assessed. The total field-aligned current is found to range from ∼0.14 to ∼9.7×104 MA, a range of nearly six orders of magnitude. The total magnetic flux content is found to range from ∼0.25 to ∼2.3×106 MWb, a range of nearly seven orders of magnitude. To the best of our knowledge, this review reports the largest range of
both the total field-aligned current and the total magnetic flux content for magnetic flux ropes in space plasmas. 相似文献
885.
In this paper, a simple technique for calculating the ideal ejector thrust augmenter of a jet engine is presented. It is based on the well-known method for averaging the parameters of a nonuniform gas flow with the entropy of the initial flow being unchanged. Making use of the technique presented, we compare the calculated data on the pressure ratio in the gas being ejected as well as the thrust boost coefficient with those obtained by the other authors. Also shown is the existence of the thrust boost maximum in the ideal and real thrust augmenters when the value of the ejection coefficient is approximately equal to 100. 相似文献
886.
R. Modzelewska M.V. Alania 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
We show that the higher range of the heliolongitudinal asymmetry of the solar wind speed in the positive polarity period (A > 0) than in the negative polarity period (A < 0) is one of the important reasons of the larger amplitudes of the 27-day variation of the galactic cosmic ray (GCR) intensity in the period of 1995–1997 (A > 0) than in 1985–1987 (A < 0). Subsequently, different ranges of the heliolongitudinal asymmetry of the solar wind speed jointly with equally important corresponding drift effect are general causes of the polarity dependence of the amplitudes of the 27-day variation of the GCR intensity. At the same time, we show that the polarity dependence is feeble for the last unusual minimum epoch of solar activity 2007–2009 (A < 0); the amplitude of the 27-day variation of the GCR intensity shows only a tendency of the polarity dependence. We present a three dimensional (3-D) model of the 27-day variation of GCR based on the Parker’s transport equation. In the 3-D model is implemented a longitudinal variation of the solar wind speed reproducing in situ measurements and corresponding divergence-free interplanetary magnetic field (IMF) derived from the Maxwell’s equations. We show that results of the proposed 3-D modeling of the 27-day variation of GCR intensity for different polarities of the solar magnetic cycle are in good agreement with the neutron monitors experimental data. To reach a compatibility of the theoretical modeling with observations for the last minimum epoch of solar activity 2007–2009 (A < 0) a parallel diffusion coefficient was increased by ∼40%. 相似文献
887.
V.V. Lyahov V.M. Neshchadim 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
A procedure for investigating the stability of a current sheath, taking into account the effect of plasma polarization, is offered. The kinetic equation with a self-consistent electromagnetic field for perturbation of the distribution function is solved. On the basis of this solution, the tensor of dielectric permeability for a non-electroneutral current sheath plasma is calculated, and the dispersion equation for the study of possible instability modes of this current sheath is obtained. The instability of the current sheath of the magnetospheric tail with respect to tearing perturbations, and the influence of the effect of plasma polarization on the development of tearing instability, are investigated. 相似文献
888.
Negative effect of cosmic ray particles is a serious danger for astronauts and onboard equipment. When planning interplanetary
flights it becomes one of the main obstacles. The aim of this work is to analyze currently available methods of protecting
spacecraft against cosmic rays using magnetic fields and to choose the most effective method. Three variants of protection
systems were considered, two of which had been described in scientific literature: with azimuth and axial magnetic filed.
The third, more general method (with helical magnetic field) is suggested here for the first time. The first two variants
are extreme special cases of the third one. The exact solution is obtained for the problem of motion of a charged relativistic
particle in the helical magnetic field, and a criterion of particle reflection is determined. A comparative analysis of reflection
characteristics of the chosen systems has been performed, and the conclusion about the optimal configuration of the magnetic
protection is drawn. 相似文献
889.
The investigation of stability and precision of the previously proposed implicit scheme of direct integration for the finite
element equations of motion is presented. The scheme parameter values that ensure its unconditional stability in the nonlinear
problems are determined and comparison with existing procedures is given. 相似文献
890.
T. Z. Gimadieva 《Russian Aeronautics (Iz VUZ)》2009,52(1):37-40
A mathematical model of motion for a string of liferafts being water dropped is presented under the assumption of a plane system motion. An example of calculations is given. 相似文献