Bianchi Type I Bulk Viscous Stiff Fluid Tilted Cosmological Model in General Relativity     

Raj Bali  Keshav Sharma 《Astrophysics and Space Science》2001,275(4):485-497

Bianchi Type I Bulk viscous fluid tilted cosmological model without shearviscosity is investigated. The behaviour of the model in presence andabsence of bulk viscosity is discussed. The physical and geometricalconsequences of the models are also discussed.  相似文献   

Tilted Cosmological Models Filled with Disordered Radiation in General Relativity     

Raj Bali  B.L. Meena 《Astrophysics and Space Science》2002,281(3):565-575

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The Himalayan Collisional Orogeny: A Metamorphic Perspective     

WANG Jiamin  WU Fuyuan  ZHANG Jinjiang  Gautam KHANAL  YANG Lei 《《地质学报》英文版》2022,96(6):1842-1866

This paper introduces how crustal thickening controls the growth of the Himalaya by summarizing the P-T-t evolution of the Himalayan metamorphic core. The Himalayan orogeny was divided into three stages. Stage 60–40 Ma: The Himalayan crust thickened to ~40 km through Barrovian-type metamorphism (15–25 °C/km), and the Himalaya rose from <0 to ~1000 m. Stage 40–16 Ma: The crust gradually thickened to 60–70 km, resulting in abundant high-grade metamorphism and anatexis (peak-P, 15–25 °C/km; peak-T, >30 °C/km). The three sub-sheets in the Himalayan metamorphic core extruded southward sequentially through imbricate thrusts of the Eo-Himalayan thrust, High Himalayan thrust, and Main Central thrust, and the Himalaya rose to ≥5,000 m. Stage 16–0 Ma: the mountain roots underwent localized delamination, causing asthenospheric upwelling and overprinting of the lower crust by ultra-high-temperature metamorphism (30–50 °C/km), and the Himalaya reached the present elevation of ~6,000 m. Underplating and imbricate thrusting dominated the Himalaya’ growth and topographic rise, conforming to the critical taper wedge model. Localized delamination of mountain roots facilitated further topographic rise. Future Himalayan metamorphic studies should focus on extreme metamorphism and major collisional events, contact metamorphism and rare metal mineralization, metamorphic decarbonation and the carbon cycle in collisional belts.  相似文献   

Laboratory experiments on the influence of soil pipes on slope failure     

Raj H. Sharma 《Landslides》2015,12(2):345-353

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Performance of flexible retaining walls supporting dry cohesionless soils under cyclic loads     

Raj Siddharthan  Emmanuel M. Maragakis 《国际地质力学数值与分析法杂志》1989,13(3):309-326

A finite element model is proposed for studying the seismic response of a flexible retaining wall/soil system. The model accounts for nonlinear hysteretic soil behaviour, and also for the increase in lateral stresses and settlement related to grain slip caused by cyclic loads. The response computed by the proposed method was compared with responses recorded at the Cambridge centrifuge facility, and found to be in reasonable agreement. The model was then used to identify the importance of factors such as flexibility of the wall and relative density of the backfill. The study reveals that the maximum bending moments given by current design procedures are nonconservative for stiffer walls. Deflections of flexible walls are of major concern. Flexible walls supporting a sand of medium density yield the greatest deflection.  相似文献   

A gravitationally non-degenerate cosmological model with expanding and shearing viscous fluid in general relativity     

Raj Bali  Deepak Raj Jain 《Astrophysics and Space Science》1987,139(1):175-181

The object of this paper is to investigate the behaviour of viscosity in a cosmological model, in which the coefficient of shear viscosity is assumed to be proportional to rate of expansion in the model. The behaviour of the model in the absence of shear viscosity is also discussed.  相似文献   

Unsteady flow of a non-Newtonian visco-elastic fluid between two coaxial circular cylinders     

Krishna Raj Choubey 《Astrophysics and Space Science》1984,105(2):301-305

In this paper, the flow of a visco-elastic liquid between two coaxial circular cylinders has been studied when inner cylinder is moving from rest for a certain period with linearly growing speed and then stops suddenly. The Laplace transform technique has been employed to solve the basic differential equations. The expression for the velocity field is obtained.  相似文献   

Magneto-viscous fluid cosmological model of plane symmetry in general relativity     

Raj Bali 《Astrophysics and Space Science》1984,107(1):155-165

The object of this paper is to investigate the behaviour of magnetic field in a viscous fluid cosmological model. Various physical and geometrical properties of the model have also been discussed.  相似文献   

Shrinkage and swelling of coal induced by desorption and sorption of fluids: Theoretical model and interpretation of a field project     

Hema J. Siriwardane  Raj K. Gondle  Duane H. Smith 《International Journal of Coal Geology》2009,77(1-2):188-202

Geologic sequestration in deep unmineable coal seams and enhanced coalbed methane production is a promising choice, economically and environmentally, to reduce anthropogenic gases such as carbon dioxide in the atmosphere. Unmineable coal seams are typically known to adsorb large amounts of carbon dioxide in comparison to the sizeable amounts of sorbed methane, which raises the potential for large scale sequestration projects. During the process of sequestration, carbon dioxide is injected into the coalbed and desorbed methane is produced. The coal matrix is believed to shrink when a gas is desorbed and swell when a gas is sorbed, sometimes causing profound changes in the cleat porosity and permeability of the coal seam. These changes may have significant impact on the reservoir performance. Therefore, it is necessary to understand the combined influence of swelling and shrinkage, and geomechanical properties including elastic modulus, cleat porosity, and permeability of the reservoir.The present paper deals with the influence of swelling and shrinkage on the reservoir performance, and the geomechanical response of the reservoir system during the process of geologic sequestration of carbon dioxide and enhanced coalbed methane production in an actual field project located in northern New Mexico. A three-dimensional swelling and shrinkage model was developed and implemented into an existing reservoir model to understand the influence of geomechanical parameters, as well as swelling and shrinkage properties, on the reservoir performance. Numerical results obtained from the modified simulator were compared to available measured values from that site and previous studies. Results show that swelling and shrinkage, and the combination of geomechanical and operational parameters, have a significant influence on the performance of the reservoir system.  相似文献   

Bianchi type VI0 magnetized bulk viscous massive string cosmological model in General Relativity     

Raj Bali  Ratna Banerjee  S. K. Banerjee 《Astrophysics and Space Science》2008,317(1-2):21-26

The paper consists of some exact solutions for a homogeneous Bianchi type VI₀ universe. The material distribution is taken to be a magnetized bulk viscous fluid in presence of massive cosmological string. We assume that current is flowing along x-direction. Therefore, the magnetic field is in yz-plane. For deterministic model of the universe, we assume that shear (σ) is proportional to the expansion (θ) and ζ θ=constant=ξ where ζ the coefficient of bulk viscosity and θ the expansion in the model. The physical and kinematical parameters of the models thus formed are discussed.  相似文献