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12.
In recent times, rapid urbanisation coupled with scarcity of land forces several structures to come up ever closer to each
other, which may sometime cause severe damage to the structures from both strength and serviceability point of view, and therefore,
a need is felt to devise simplified methods to capture the effect of footing interference. In the present study, an attempt
has been made to model the settlement behaviour of two strip footings placed in close spacing on layered soil deposit consisting
of a strong top layer underlying a weak bottom layer. Theory of elasticity is employed to derive the governing differential
equations and subsequently solved by the finite difference method. The perfectly rough strip footings are considered to be
resting on the surface of two-layer soil system, and the soil is assumed to behave as linear elastic material under a range
of static foundation load. The effect of various parameters such as the elastic moduli and thickness of two layers, clear
spacing between the footings and footing load on the settlement behaviour of closely spaced footings has been determined.
The variation of vertical normal stress at the interface of two different soil layers as well as at the base of the failure
domain also forms an important part of this study. The results are presented in terms of settlement ratio (ξδ), and their variation is obtained with the change in clear spacing between two footings. The present theoretical investigation
indicates that the settlement of closely spaced footings is found to be higher than that of single isolated footing, which
further reduces with increase in the spacing between the footings. 相似文献
13.
Anirudh Pradhan Vineet K. Yadav Lallan Yadav A. K. Yadav 《Astrophysics and Space Science》2007,312(3-4):267-273
Cylindrically symmetric inhomogeneous cosmological model for perfect fluid distribution with electromagnetic field is obtained.
The source of the magnetic field is due to an electric current produced along the z-axis. F
12 is the non-vanishing component of electromagnetic field tensor. To get the deterministic solution, it has been assumed that
the expansion θ in the model is proportional to the shear σ. Physical and geometric aspects of the models are also discussed in presence and absence of magnetic field.
相似文献
14.
Anirudh Pradhan Anil Kumar Yadav R. P. Singh Vipin Kumar Singh 《Astrophysics and Space Science》2007,312(3-4):145-150
A new class of solutions of Einstein field equations has been investigated for inhomogeneous cylindrically symmetric space-time with string source. To get the deterministic solution, it has been assumed that the expansion (θ) in the model is proportional to the eigen value σ 1 1 of the shear tensor σ i j . Certain physical and geometric properties of the models are also discussed. 相似文献
15.
Anirudh Pradhan Hassan Amirhashchi Rekha Jaiswal 《Astrophysics and Space Science》2011,334(2):249-260
A new class of dark energy models in a Locally Rotationally Symmetric Bianchi type-II (LRS B-II) space-time with variable
equation of state (EoS) parameter and constant deceleration parameter have been investigated in the present paper. The Einstein’s
field equations have been solved by applying a variation law for generalized Hubble’s parameter given by Berman: Nuovo Cimento
74:182 (1983) which generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential-law
form. Using these two forms, Einstein’s field equations are solved separately that correspond to expanding singular and non-singular
models of the universe respectively. The dark energy EoS parameter ω is found to be time dependent and its existing range for both models is in good agreement with the three recent observations
of (i) SNe Ia data (Knop et al.: Astrophys. J. 598:102 (2003)), (ii) SNe Ia data collaborated with CMBR anisotropy and galaxy clustering statistics (Tegmark et al.: Astrophys. J. 606:702 (2004)) and latest (iii) a combination of cosmological datasets coming from CMB anisotropies, luminosity distances of high redshift
type Ia supernovae and galaxy clustering (Hinshaw et al.: Astrophys. J. Suppl. 180:225 (2009); Komatsu et al. Astrophys. J. Suppl. 180:330 (2009)). The cosmological constant Λ is found to be a positive decreasing function of time and it approaches a small positive value
at late time (i.e. the present epoch) which is corroborated by results from recent supernovae Ia observations. The physical
and geometric behaviour of the universe have also been discussed in detail. 相似文献
16.
The present study deals with locally rotationally symmetric (LRS) Bianchi type II cosmological model representing massive
string. The energy-momentum tensor for such string as formulated by Letelier (Phys. Rev. D 28:2414, 1983) is used to construct massive string cosmological model for which we assume that the expansion (θ) in the model is proportional to the shear (σ). This condition leads to A=B
m
, where A and B are the metric coefficients and m is proportionality constant. For suitable choice of constant m, it is observed
that in early stage of the evolution of the universe string dominates over the particle whereas the universe is dominated
by massive string at the late time. Our model is in accelerating phase which is consistent to the recent observations of type
Is supernovae. Some physical and geometric behavior of the model is also discussed. 相似文献
17.
In this paper we study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic
FRW universe filled with barotropic fluid and dark energy. The scale factor is considered as a power law function of time
which yields a constant deceleration parameter. We consider the case when the dark energy is minimally coupled to the perfect
fluid as well as direct interaction with it. The cosmic jerk parameter in our derived models is consistent with the recent
data of astrophysical observations. It is concluded that in non-interacting case, all the three open, close and flat universes
cross the phantom region whereas in interacting case only open and flat universes cross the phantom region. We find that during
the evolution of the universe, the equation of state (EoS) for dark energy ω
D
changes from ω
D
>−1 to ω
D
<−1, which is consistent with recent observations. 相似文献
18.
The present study deals with a spatially homogeneous and anisotropic Bianchi-I cosmological models representing massive strings.
The energy-momentum tensor, as formulated by Letelier (1983), has been used to construct massive string cosmological models for which we assume the expansion scalar in the models is
proportional to one of the components of shear tensor. The Einstein’s field equations have been solved by applying a variation
law for generalized Hubble’s parameter in Bianchi-I space-time. We have analysed a comparative study of accelerating and decelerating
models in the presence of string scenario. The study reveals that massive strings dominate in the decelerating universe whereas
strings dominate in the accelerating universe. The strings eventually disappear from the universe for sufficiently large times,
which is in agreement with current astronomical observations. 相似文献
19.
Anirudh Pradhan Rekha Jaiswal Kanti Jotania Rajeev Kumar Khare 《Astrophysics and Space Science》2012,337(1):401-413
We present two dark energy (DE) models with an anisotropic fluid in Bianchi type-VI
0 space-time by considering time dependent deceleration parameter (DP). The equation of state (EoS) for dark energy ω is found to be time dependent and its existing range for derived models is in good agreement with the recent observations.
Under the suitable condition, the anisotropic models approach to isotropic scenario. We also find that during the evolution
of the universe, the EoS parameter for DE changes from ω>−1 to ω=−1 in first model whereas from ω>−1 to ω<−1 in second model which is consistent with recent observations. The cosmological constant Λ is found to be a positive decreasing
function of time and it approaches a small positive value at late time (i.e. the present epoch) which is corroborated by results
from recent type Ia supernovae observations. The cosmic jerk parameter in our derived models is also found to be in good agreement
with the recent data of astrophysical observations. The physical and geometric aspects of both the models are also discussed
in detail. 相似文献
20.
Anil Kumar Yadav Anirudh Pradhan Ajay Kumar Singh 《Astrophysics and Space Science》2012,337(1):379-385
The present study deals with spatially homogeneous and totally anisotropic locally rotationally symmetric (LRS) Bianchi type
I cosmological model with variable G and Λ in presence of imperfect fluid. To get the deterministic model of Universe, we assume that the expansion (θ) in the model is proportional to shear (σ). This condition leads to A=ℓB
n
, where A, B are metric potential. The cosmological constant Λ is found to be decreasing function of time and it approaches a small positive
value at late time which is supported by recent Supernovae Ia (SN Ia) observations. Also it is evident that the distance modulus
curve of derived model matches with observations perfectly. 相似文献