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Search Results: 1 - 10 of 89 matches for " Aseem Miglani "
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Plane Strain Deformation of a Poroelastic Half-space in Welded Contact with Transversely Isotropic Elastic Half-Space
International Journal of Engineering Science and Technology , 2012,
Abstract: The Biot linearized theory for fluid saturated porous materials is used to study the plane strain deformation of an isotropic, homogeneous, poroelastPic half space in welded contact with a homogeneous, transversely isotropic, elastic half space caused by an inclined line-load in elastic half space. The integral expressions for the displacements and stresses in the two half spaces in welded contact are obtained from the corresponding expressions for an unbounded transversely isotropic elastic and poroelastic medium by applying boundary conditions at the interface. The integrals for the inclined line-load are solved analytically for the limiting casei.e. undrained conditions in high frequency limit. The undrained displacements, stresses and pore pressure are shown graphically. Expression for the pore pressure is also calculated for undrained conditions in the high frequency limit.
Deformation due to distributed sources in micropolar thermodiffusive medium
Sachin Kaushal,Aseem Miglani
Mathematical Sciences Quarterly Journal , 2010,
Abstract: The general solution to the field equations in micropolar generalized thermodiffusive in the context of G-L theory is investigated by applying the Laplace and Fourier transform's as a result of various sources. An application of distributed normal forces or thermal sources or potential sources has been taken to show the utility of the problem. To get the solution in the physical form, a numerical inversion technique has been applied. The transformed components of stress, temperature distribution and chemical potential for G-L theory and CT theory has been depicted graphically and results are compared analytically to show the impact of diffusion, relaxation times and micropolarity on these quantities. Some special case of interest are also deduced from present investigation.
Crisis urbana y respuesta institucional en dos megaciudades. Lecciones del manejo de la devastación sísmica en las ciudades de México y Los ángeles
Aseem Inam
Estudios Demográficos y Urbanos , 2002,
Abstract: Apoyado en un marco analítico derivado tanto de la teoría institucional como de la teoría de la planeación urbana, este estudio examina los resultados de dos programas creados para restablecer el orden y la estabilidad después de una situación de crisis urbana. Estos son: el Programa de Renovación Habitacional Popular en la Ciudad de México, establecido luego del terremoto de 1985, y el Programa Ghost Town establecido en la ciudad de Los Angeles, California, después del terremoto de 1994. Ambos han sido encomiados por su accionar rápido, su financiamiento masivo, el mejoramiento de las condiciones preexistentes, la participación comunitaria, y la coordinación institucional. El argumento principal de este estudio es que las intituciones de planeación urbana en ambas ciudades fueron efectivas durante la crisis provocada por los sismos, principalmente porque se apoyaron en rutinas institucionales: un tipo de procedimiento que suele ser denostado o subestimado porque tiene la reputación de ser extremadamente burocrático. Las instituciones de planeación en la Ciudad de México y Los Angeles respondieron con efectividad porque fueron capaces de adaptar rutinas institucionales, en forma rápida y eficiente, a circunstancias imprevistas y dramáticas. Planteado como un estudio de caso, este análisis se propone clarificar y explicar la dinámica de la planeación urbana en un contexto de crisis de dos maneras: Primero, los estudios de caso demuestran que un análisis institucional explícito y sistemático ayuda a entender mejor qué elementos dan buenos resultados en materia de planeación urbana, y por qué. Segundo, el análisis institucional muestra bajo qué condiciones pueden servir las rutinas institucionales como herramientas poderosas y efectivas para resolver situaciones imprevistas sin importar el contexto sociopolítico dominante.
A Covariant Road to Spatial Averaging in Cosmology : Scalar Corrections to the Cosmological Equations
Aseem Paranjape
Physics , 2007, DOI: 10.1142/S0218271808012322
Abstract: A consistent approach to Cosmology requires an explicit averaging of the Einstein equations, to describe a homogeneous and isotropic geometry. Such an averaging will in general modify the Einstein equations. The averaging procedure due to Buchert has attracted considerable attention recently since it offers the tantalizing hope of explaining the phenomenon of dark energy through such corrections. This approach has been criticized, however, on the grounds that its effects may be gauge artifacts. We apply the fully covariant formalism of Zalaletdinov's Macroscopic Gravity and show that, after making some essential gauge choices, the Cosmological equations receive \emph{spacetime scalar} corrections which are therefore observable in principle, and further, that the broad structure of these corrections is \emph{identical} to those derived by Buchert.
The Averaging Problem in Cosmology
Aseem Paranjape
Physics , 2009,
Abstract: This thesis deals with the averaging problem in cosmology, which has gained considerable interest in recent years, and is concerned with correction terms (after averaging inhomogeneities) that appear in the Einstein equations when working on the large scales appropriate for cosmology. It has been claimed in the literature that these terms may account for the phenomenon of dark energy which causes the late time universe to accelerate. We investigate the nature of these terms by using averaging schemes available in the literature and further developed to be applicable to the problem at hand. We show that the effect of these terms when calculated carefully, remains negligible and cannot explain the late time acceleration.
Nonlinear Structure Formation, Backreaction and Weak Gravitational Fields
Aseem Paranjape
Physics , 2008, DOI: 10.1051/eas/0936009
Abstract: There is an ongoing debate in the literature concerning the effects of averaging out inhomogeneities (``backreaction'') in cosmology. In particular, some simple models of structure formation studied in the literature seem to indicate that the backreaction can play a significant role at late times, and it has also been suggested that the standard perturbed FLRW framework is no longer a good approximation during structure formation, when the density contrast becomes nonlinear. In this work we use Zalaletdinov's covariant averaging scheme (macroscopic gravity or MG) to show that as long as the metric of the Universe can be described by the perturbed FLRW form, the corrections due to averaging remain negligibly small. Further, using a fully relativistic and reasonably generic model of pressureless spherical collapse, we show that as long as matter velocities remain small (which is true in our model), the perturbed FLRW form of the metric can be explicitly recovered. Together, these results imply that the backreaction remains small even during nonlinear structure formation, and we confirm this within the toy model with a numerical calculation.
Backreaction of Cosmological Perturbations in Covariant Macroscopic Gravity
Aseem Paranjape
Physics , 2008, DOI: 10.1103/PhysRevD.78.063522
Abstract: The problem of corrections to Einstein's equations arising from averaging of inhomogeneities ("backreaction") in the cosmological context, has gained considerable attention recently. We present results of analysing cosmological perturbation theory in the framework of Zalaletdinov's fully covariant Macroscopic Gravity. We show that this framework can be adapted to the setting of cosmological perturbations in a manner which is free from gauge related ambiguities. We derive expressions for the backreaction which can be readily applied in \emph{any} situation (not necessarily restricted to the linear perturbations considered here) where the \emph{metric} can be brought to the perturbed FLRW form. In particular these expressions can be employed in toy models studying nonlinear structure formation, and possibly also in N-body simulations. Additionally, we present results of example calculations which show that the backreaction remains negligible well into the matter dominated era.
Cosmology with Galaxy Clusters: Systematic Effects in the Halo Mass Function
Aseem Paranjape
Physics , 2014, DOI: 10.1103/PhysRevD.90.023520
Abstract: We investigate potential systematic effects in constraining the amplitude of primordial fluctuations \sigma_8 arising from the choice of halo mass function in the likelihood analysis of current and upcoming galaxy cluster surveys. We study the widely used N-body simulation fit of Tinker et al. (T08) and, as an alternative, the recently proposed analytical model of Excursion Set Peaks (ESP). We first assess the relative bias between these prescriptions when constraining \sigma_8 by sampling the ESP mass function to generate mock catalogs and using the T08 fit to analyse them, for various choices of survey selection threshold, mass definition and statistical priors. To assess the level of absolute bias in each prescription, we then repeat the analysis on dark matter halo catalogs in N-body simulations designed to mimic the mass distribution in the current data release of Planck SZ clusters. This N-body analysis shows that using the T08 fit without accounting for the scatter introduced when converting between mass definitions (alternatively, the scatter induced by errors on the parameters of the fit) can systematically over-estimate the value of \sigma_8 by as much as 2\sigma\ for current data, while analyses that account for this scatter should be close to unbiased in \sigma_8. With an increased number of objects as expected in upcoming data releases, regardless of accounting for scatter, the T08 fit could over-estimate the value of \sigma_8 by ~1.5\sigma. The ESP mass function leads to systematically more biased but comparable results. A strength of the ESP model is its natural prediction of a weak non-universality in the mass function which closely tracks the one measured in simulations and described by the T08 fit. We suggest that it might now be prudent to build new unbiased ESP-based fitting functions for use with the larger datasets of the near future.
Radiative Effect on Flow and Heat Transfer over a Vertically Oscillating Porous Flat Plate Embedded in Porous Medium with Oscillating Surface Temperature  [PDF]
Monika Miglani, Net Ram Garg, Mukesh Kumar Sharma
Open Journal of Fluid Dynamics (OJFD) , 2016, DOI: 10.4236/ojfd.2016.62010
Abstract: The effect of radiation on flow and heat transfer over a vertically oscillating porous flat plate embedded in porous medium with oscillating surface temperature is investigated. The analytic solutions of momentum and energy equations are obtained. The velocity and temperature profiles are computed. The frictional force at the plate due to viscosity of fluid is estimated in terms of non dimensional skin friction coefficient and heat convection at the plate is estimated in the form of Nusselt number. The effects of physical parameters Prandtl number Pr, Grashof number Gr, Suction parameter S and radiative parameter R on velocity and temperature profiles are analyzed through graphs. The effects of oscillation on the velocity and temperature profiles are shown through 3-D surface plot.
昆虫学报 , 2013,
Abstract: 卵黄蛋白原(vitellogenin,Vg)是主要的卵黄蛋白前体,在雌虫血餐之后在脂肪体内大量合成。卵黄蛋白原的调节元件已经被用于驱动蚊子(与寄生虫发生最大相互作用的场所)中抗寄生基因的组织特异性表达。不过,迄今为止,对在印度引起60%~70%疟疾发生的库态按蚊Anophelesculicifacies中的内源启动子尚未进行过分析。本研究通过PCR扩增了包括5′端上游调节区在内的库态按蚊A.culicifacies卵黄蛋白原基因,并命名为AncuVg(GenBank登录号为JN113091)。它含有一个大约6.2kb的开放阅读框,编码2052个氨基酸,具有一个16个氨基酸残基的推断的信号肽。也含有一个N_Vitellogenin区和一个VWF型D区,这两个区在其他昆虫卵黄蛋白原中也保守。估计多肽分子量为238.0kDa,含有4个共有的(RXXR/S)切割位点,C端附近有一个GL/ICG基序,其后是9个半胱氨酸残基和1个位于GL/ICCG基序上游第18个氨基酸残基处的DGXR基序。在推断的氨基酸序列上发现3个聚丝氨酸区,其中2个位于氨基端,1个位于羧基端。根据同义密码子相对使用概率值,通过有效密码子数,测定了蚊子卵黄蛋白原基因密码子的偏倚性程度。也预测了库态按蚊A.culicifaciesVg的三维结构。分析了AncuVg基因,以理解Vg基因的转录调节。对Vg基因5′端上游区进行的系统发育分析表明,它们聚类于蚊子的3大分枝。也用各种生物信息学工具分析分析了Vg的同源性和特征。
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