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Mahantesh S. Hiremath Ranbir S. Sandhu Leslie W. Morland William E. Wolfe 《国际地质力学数值与分析法杂志》1988,12(2):121-139
Biot's dynamic equations of motion for one-dimensional wave propagation in a fluid-saturated linear elastic isotropic soil are solved using Laplace transformation followed by numerical inversion and the results compared with a direct finite element formulation. A soil column of finite dimension subjected to velocity boundary conditions is analysed, allowing for reflection of waves from boundaries. Comparison of time histories at given points along the column shows that the finite element solution gives good agreement with the Laplace transform solution for low as well as high drag. 相似文献
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M. Toscano J. S. Sandhu M. Bailes R. N. Manchester M. C. Britton S. R. Kulkarni S. B. Anderson B. W. Stappers 《Monthly notices of the Royal Astronomical Society》1999,307(4):925-933
We present improved timing parameters for 13 millisecond pulsars (MSPs), including nine new proper motion measurements. These new proper motions bring to 23 the number of MSPs with measured transverse velocities. In light of these new results we present and compare the kinematic properties of MSPs with those of ordinary pulsars. The mean transverse velocity of MSPs was found to be 85±13 km s−1 , a value consistent with most models for the origin and evolution of MSPs and approximately a factor of 4 lower than that of ordinary pulsars. We also find that, in contrast to young ordinary pulsars, the vast majority of which are moving away from the Galactic plane, almost half of the MSPs are moving towards the plane. This near-isotropy would be expected of a population that has reached dynamic equilibrium. Accurate measurements of MSP velocities have allowed us to correct their measured spin-down rates for Doppler acceleration effects, and thereby derive their intrinsic magnetic field strengths and characteristic ages. We find that close to half of our sample of MSPs have a characteristic age comparable to or greater than the age of the Galactic disc. 相似文献
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A Fourier transform approach is applied to the transient analysis of dynamic soil–structure interaction under SH-motion. The governing equations are formulated in the frequency domain using a Finite Element–Boundary Element (FE–BE) coupling method. After solving the transformed problem, the transient solution is obtained using the discrete inverse Fourier transform with a fast Fourier transform algorithm. Two examples are presented in order to show the numerical performance of the proposed technique. 相似文献
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The performance of a coupled Finite Element—Analytic method in solving elastic wave scattering in infinite spaces is studied for plane SH-waves. The influence of several parameters on the accuracy of the results is investigated. These parameters are the number of terms in the series solution, the number of compatibility points across an imaginary circular interface (i.e. the points for which the continuity of both stresses and displacements are enforced), and the ratio of element dimension to wavelength in the direction of propagation. It was found that the method converges rapidly with the number of terms. Furthermore, both element dimension to wavelength ratio and the number of compatibility points significantly influence the accuracy of the approximate solution. 相似文献
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Numerical performance of some finite element schemes for analysis of seepage in porous elastic media
Several finite element schemes for analysis of seepage in porous elastic media, based on different spatial and temporal discretization, were implemented in computer programs. Their numerical performance is evaluated by comparison with the exact solution for Terzaghi's problem of one-dimensional consolidation. 相似文献
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H.S. Sandhu 《大气与海洋》2013,51(2):137-138
Abstract A small catchment in south‐central Ontario was divided into two zones to evaluate the effect of a small wetland on runoff response during spring snowmelt in 1980. Runoff from the downstream side‐slope zone was produced by a combination of saturation overland flow and subsurface flow. The response to individual snowmelt and rainfall events varied according to antecedent wetness conditions. Runoff delivery from the wetland zone was affected even more by antecedent conditions. For the first and largest event, the response of the wetland was very similar to that of the side‐slope zone, but as the runoff season progressed, the increasing storage capacity of the wetland resulted in more marked contrasts. Quickflow yields and peak flows were much lower from the wetland and response times were longer. Over the whole runoff season, the wetland yielded substantially less runoff mainly because the perched ground water system that sustained it became isolated from the regional ground water system, and this limited the extent of the runoff contributing area in the wetland zone. 相似文献
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Har Amrit Singh Sandhu Hemendra Singh Gusain Manoj Kumar Arora Arun Bawa 《Journal of the Indian Society of Remote Sensing》2018,46(11):1835-1840
Dokriani Glacier is regarded as one of the important glaciers of Bhagirathi River basin, which fed river Ganges. The length of the glacier is about 4.6 km, and snout elevation is about 4028 m m.s.l. The mass balance of this glacier was calculated using field-based measurements for few years during 1994 to 2000. However, due to remote and poor accessibility, the field-based measurements could not continue; thus, remote sensing-based methods become useful tool to estimate the long-term mass balance of the glacier. In this study, glacier mass balance has been determined using accumulation area ratio (AAR) method. Remote sensing data sets, e.g. Landsat TM, ETM?+?and OLI, have been used to estimate AAR for different years from 1994 to 2014. An attempt has also been made to develop a mathematical relationship between remote sensing-derived AAR and field-observed mass balance data of the glacier. Further, this relationship has been used to estimate mass balance of the glacier for different years using remote sensing-derived AAR. Estimated mass balance was validated from ground-observed mass balance for few years. The field-observed and remote sensing-derived mass balance data are compared and showed high correlation. It has been observed that AAR for the Dokriani Glacier varies from 0.64 to 0.71. Mass balance of the glacier was observed between ??15.54 cm and ??50.95 cm during the study period. The study highlights the application of remote sensing in mass balance study of the glaciers and impact of climate change in glaciers of Central Indian Himalaya. 相似文献
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Variational principles governing dynamics of fluid-saturated linear elastic porous media are derived. Complementary as well as direct formulations are discussed. Discontinuities in the field variables, the approximation space and the excitation are allowed for. Extensions of the variational principles to relax smootheness requirements on certain field variables are introduced along with some specizalizations convenient for finite element applications. 相似文献
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Measurements of river water quality at Haridwar, India, taken during 2005–2006 show that the river water does not meet the World Health Organization and Bureau of Indian Standards criteria of drinking water quality, especially with respect to total coliform and fecal coliform. This study investigates the removal of pathogens at a river bank filtration site in Haridwar. Using the quality of river water and the quality of abstracted water from a nearby production well, semi‐empirical models based on the concept of filtration coefficient are developed and tested for their effectiveness in removing pathogens under varying bacteriological quality of source water. A two‐tier model, which includes the effect of clogged layer, is developed to obtain an equivalent filtration coefficient. This coefficient is found to be linearly related with natural logarithm of the concentration of pathogens in the source water. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献