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Grigori Muravskii 《地震工程与结构动力学》2000,29(4):399-418
The paper presents a study of time-harmonic surface waves in a linearly inhomogeneous half-space. The study is based on the solution of that problem for an arbitrary (from 0 to 1/2) value of Poisson's ratio. Vertical vibrations due to a vertical harmonic force, which at large distances from the force represent Rayleigh-type waves, and transverse horizontal vibrations due to a horizontal force, which at large distances form waves of Love's type, are considered in detail. Material damping is taken into consideration. Inhomogeneity significantly affects relationships connecting wave characteristics and the frequency of vibration, and it is shown in the paper how this fact can be used for determining material properties (surface shear modulus, degree of inhomogeneity, damping ratio) with the help of experimental results concerning wave propagation over the surface of the half-space. It is shown that for forced waves the relationship between the wave phase angle and distance can significantly differ from a straight line, i.e. the wave number varies with distance. Therefore, it is desirable to relate experimental and theoretical results to such parts of wave propagation line, which correspond to same phase angle intervals. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Grigori Chapiro Alexei A. Mailybaev Aparecido J. de Souza Dan Marchesin Johannes Bruining 《Computational Geosciences》2012,16(3):799-808
There is a renewed interest in using combustion for the recovery of medium viscosity oil. We consider the combustion process
when air is injected into the porous medium containing some fuel and inert gas. Commonly the reaction rate is negligible at
low temperatures, hence the possibility of oxygen breakthrough. In this case, the oxygen gets in contact with the fuel in
the downstream zone leading to slow reaction. We focus on the case when the reaction is active for all temperatures, but heat
losses are negligible. For a combustion model that includes heat and mass balance equations, we develop a method for calculating
the wave profile in the form of an asymptotic expansion and derive its zero- and first-order approximations. This wave profile
appears to be different from wave profiles analyzed in other papers, where only the reaction at the highest temperatures was
taken into account. The combustion wave has a long decaying tail. This tail is hard to observe in the laboratory because heat
losses must be very small for the long tail to form. Numerical simulations were performed in order to validate our asymptotic
formulae. 相似文献
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G. B. Muravskii 《Soil Dynamics and Earthquake Engineering》2001,21(8):661-669
It is shown in this paper that experimental results on stiffness and damping corresponding to cyclic deforming of soils can be well approached theoretically on an interval of strain variation from zero to arbitrary large values of strains. For this purpose, the following two methods are recommended: a modification of the hysteretic model obeying Masing's rule by adding elastic stresses to pure hysteretic stresses that do not change the corresponding backbone curve; and, as the second method, a non-linear model with frequency independent loss of energy in periodic processes. It is shown that in the area close to the free surface of soil, normalized strains resulting from propagation of seismic waves can be very large, even in the case of an input motion of relatively low intensity. Therefore, a using analytical approximations for experimental stress–strain relationships, which are suitable only for an interval of small and medium values of normalized strains, is insufficient in seismic response analysis. 相似文献
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G. B. Muravskii 《地震工程与结构动力学》2007,36(1):13-33
In the paper, several causal linear models leading to nearly frequency independent complex stiffness are studied in time and frequency domains. Along with Biot model other three hereditary models are introduced into analysis. They all ensure practical constancy for damping properties but have limitations concerned with an increase in the real part of complex stiffness of corresponding material elements, as frequency grows. A new suggested method deals with given mechanical system as a whole: the imaginary part of the system compliance is constructed assuming that all elements have constant stiffness (with a modification for imaginary parts near zero frequency) and further the imaginary part of the system is used directly for studying transient vibrations supposing causality of the given mechanical system. The corresponding real part (not needed in the transient response analysis) is determined by Hilbert transformation. Examples relating to systems with one, two and infinite (shear beam) degrees of freedom are carried out for five compared models, allowing to reveal advantages and shortcomings of the models. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Thierry de Wit Dudok Ashot A. Chilingarian Grigori G. Karapetyan 《Acta Geophysica》2009,57(1):102-115
The analysis of weak variations in the energetic particle flux, as detected by neutron or muon monitors, can often be considerably
improved by analysing data from monitor networks and thereby exploiting the spatial coherence of the flux. We present a statistical
framework for carrying out such an analysis and discuss its physical interpretation. Two other applications are also presented:
filling data gaps and removing trends. This study focuses on the method and its various uses. 相似文献
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