Disturbances due to time-dependent body forces in a non-isotropic elastic medium     

Sasadhar De 《Pure and Applied Geophysics》1971,87(1):128-133

Summary In this paper, the disturbances produced due to time-dependent body forces in an anisotropic elastic medium resting on a semi-infinite non-isotropic layer have been discussed.  相似文献   

On the wave propagation in inhomogeneous non-isotropic media     

Sasadhar De 《Pure and Applied Geophysics》1971,89(1):118-125

Summary FollowingEason, we have discussed here the propagation of elastic waves in non-homogeneous spheres and cylinders when the curved surface is given a uniform normal loading. The material is assumed to be transversely isotropic with respect to a direction of symmetry, the stress and displacement components within the body may be assumed to depend on one space co-ordinate and time alone. The particular case in which the elastic parameters are proportional to (radius) ⁿ has been considered.  相似文献   

Problem on the vibrations of plates     

Sasadhar De 《Pure and Applied Geophysics》1971,92(1):45-51

Summary In this paper, the problem on the vibrations of rectangular, elliptical and circular plates of non-isotropic material have been solved by using Galerkin's method. With the help of this method, the same problem for an isotropic circular plate has also been considered at the end.  相似文献   

On love waves in heterogeneous media     

Tapan Kumar De 《Pure and Applied Geophysics》1968,70(1):18-21

Summary Love waves in a half space with one homogeneous elastic layer overlying a semiinfinite medium having elastic properties varying with depth has been considered. The frequency equation for small wave lengths has been obtained, considering general variation, and has been shown to involve the first three derivatives of the rigidity of the heterogeneous medium at its interface with the homogeneous layer.  相似文献   

A SIMPLE PROGNOSTIC CLOSURE ASSUMPTION TO DEEP CONVECTIVE PARAMETERIZATION:I          下载免费PDF全文

Chen Dehui  Philippe Bougeault 《Acta Meteorologica Sinica》1993,7(1):1-18

In this work,the problem of dependency of the predicted rainfall upon the grid-size in mesoscale numerical weatherprediction models is addressed.We argue that this problem is due to (i) the violation of the quasi-equilibrium assump-tion,which is underlying most existing convective parameterization schemes,and states that the convective activity maybe considered in instantaneous equilibrium with the larger-scale forcing;and (ii) the violation of the hydrostatic approx-imation,made in most mesoscale models,which would induce too large-scale circulation in occurrence of strong con-vection.On the contrary,meso-β and meso-α scale models,i.e.models with horizontal grid size ranging from 10 to 100km,have a capacity to resolve motions with characteristic scales close to the ones of the convective motions.Wehypothesize that a possible way to eliminate this problem is (i) to take a prognostic approach to the parameterization ofdeep convection,whereby the quantities that describe the activity of convection are no longer diagnosed from the instan-taneous value of the large-scale forcing,but predicted by time-dependent equations,that integrate the large-scale forc-ing over time;(ii)to introduce a mesoscale parameter which varies systematically with the grid size of the numericalmodel in order to damp large-scale circulation usually too induced when the grid size becomes smaller (from 100 km to10 kin).We propose an implementation of this idea in the frame of one existing scheme,already tested and used for along time at the French Weather Service.The results of the test through one-dimensional experiments with the Phase Ⅲof GATE data are reported in this paper;and the ones on its implementation in the three-dimensional model with theOSCAR data will be reported in a companion paper.  相似文献   

The efficiency of the conversion of solar energy into wind energy by means of Hadley cells   总被引：1，自引：0，他引：1  

A. De Vos  P. van der Wel 《Theoretical and Applied Climatology》1993,46(4):193-202

Summary In the present paper, we apply endoreversible thermodynamics in order to calculate the upper bound for the fraction of solar energy absorbed by the Earth, that can be converted into the mechanical energy present in the atmosphere. We assume the presence of six Hadley cells in the Earth's wind system and find an upper limit of 1.17%. For Mars we assume a single Hadley cell and find an upper limit of 0.87%.With 10 Figures  相似文献   

Preliminary Sr and Nd isotopic data for recent lavas from Vesuvius volcano     

Graziella Caprarelli  Shigeko Togashi  Benedetto De Vivo 《Journal of Volcanology and Geothermal Research》1993,58(1-4)

  相似文献   

Ground deformations in collapsed caldera structures     

Giuseppe De Natale  Folco Pingue 《Journal of Volcanology and Geothermal Research》1993,57(1-2)

A method is presented to analyze the effect of stress-strain discontinuities on the ground deformations generated by a pressure source. This is meant to simulate the effects due to caldera structures, likely to present fractured zones at the borders of the collapsed area. A method originally developed by Crouch (1976) to solve plane-strain problems has been used to simulate deformation curves for several source and discontinuity geometries. The main result is that the location of the discontinuities controls the extension of the deformed zone, and always reduces it with respect to a continuous medium. With respect to a homogeneous medium the presence of lateral discontinuities also acts towards lowering the overpressure required to produce a given amount of deformation. These results indicate that, when analyzing ground deformations in calderas, the use of classical methods involving continuous media should be avoided, or at least taken with caution. These methods, in fact, assume that the extension of the deformed zone is only linked to the source depth.Some examples of ground deformations in active calderas have been analyzed in the framework of the results obtained from theoretical modeling. Four calderas recently affected by ground deformations have been considered: Rabaul (New Guinea), Campi Flegrei (Italy), Long Valley and Yellowstone (U.S.A.). The effects of collapsed structures on the deformation field are possibly evidenced for all the four calderas. At Rabaul and Campi Flegrei, the fracture systems mainly affecting the ground deformations probably represent younger, innermost collapses and are well evidenced by seismicity studies. Ground deformations are here concentrated in an area much smaller than the one enclosed by geologically visible caldera rims. In particular, at Rabaul, the effect of the innermost collapse can explain the high concentration of the uplift in the period 1971–1985, previously modeled by a very shallow source (1–3 km) in terms of overpressure in the main magma chamber, probably located at 4–5 km of depth.  相似文献   

A SIMPLE PROGNOSTIC CLOSURE ASSUMPTION TO DEEP CONVECTIVE PARAMETERIZATION:Ⅱ          下载免费PDF全文

Chen Dehui  Philippe Bougeault 《Acta Meteorologica Sinica》1993,7(2):212-223

A series of 3D predictions,dealing with the development of a heavy storm observed during the OSCAR experiment,were carried out by utilizing the PERIDOT model,and introducing alternatively the cumulus parameterization scheme of Bougeault (1985) and the prognostic one (Chen,1989;Chen and Bougeault,1993),with three different grid sizes:160 km,80 km,40 km.The feasibility of the new prognostic scheme and its improvement on the problem of dependency of the predicted rainfall upon the grid size of the numerical model were verified by comparison of the rainfall observed and those predicted.The results demonstrate that,in general,the predicted rainfall increases when the grid size decreases for both diagnostic and prognostic schemes.However,with the new prognostic scheme,the numerical model is capable,on the one hand,for the larger grid sizes,to increase the rainfall,which is under-estimated with the scheme of Bougeault (1985);on the another hand,for the smaller grid sizes,to reduce the rainfall,which is usually over-estimated.In other word,there is an obvious improvement on the problem under study.  相似文献   

The Crust of the Western Mediterranean Ridge From Deep Seismic Data and Gravity Modelling   总被引：2，自引：0，他引：2  

C. Truffert  N. Chamot-Rooke  S. Lallemant  B. De  Voogd  P. Huchon  X. Le  Pichon 《Geophysical Journal International》1993,114(2):360-372

  相似文献