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921.
Victor Vilarrasa Diogo Bolster Marco Dentz Sebastia Olivella Jesus Carrera 《Transport in Porous Media》2010,85(2):619-639
The injection of supercritical CO2 in deep saline aquifers leads to the formation of a CO2 plume that tends to float above the formation brine. As pressure builds up, CO2 properties, i.e. density and viscosity, can vary significantly. Current analytical solutions do not account for CO2 compressibility. In this article, we investigate numerically and analytically the effect of this variability on the position
of the interface between the CO2-rich phase and the formation brine. We introduce a correction to account for CO2 compressibility (density variations) and viscosity variations in current analytical solutions. We find that the error in
the interface position caused by neglecting CO2 compressibility is relatively small when viscous forces dominate. However, it can become significant when gravity forces
dominate, which is likely to occur at late times of injection. 相似文献
922.
Victor S. Aksenov Dmitrii I. Baklanov Sergey V. Golovastov Victor V. Golub Vladimir P. Efremov Andrey S. Saveliev Vladislav V. Volodin 《Flow, Turbulence and Combustion》2010,84(4):607-616
The present paper describes the influence of magnetic field on the spark discharge utilized for initialization of detonation. The method of schlieren time-based scanning shows the increase of shock wave velocity in the case when magnetic field was applied to the area of electrical discharge in the air. The critical energy values are obtained for a direct initialization of detonation in hydrogen–air and hexane–air mixtures. Magnetic field has a significant influence on the deflagration–combustion transition in both mixtures at the critical energy values. Pressure and velocity of the shock front were measured by ICP pressure transducers, flame front was recorded by photo-diodes. Two cases were studied experimentally: external magnetic field is produced by inductance coils connected to capacitor; own magnetic field is induced directly by discharge current in the cables positioned in special way. 相似文献
923.
924.
Quasilinearity below the 1st eigenvalue 总被引:1,自引:0,他引:1
Victor L. Shapiro 《Proceedings of the American Mathematical Society》2001,129(7):1955-1962
This paper establishes the existence of two nontrivial weak solutions for a quasilinear Dirichlet problem below the first eigenvalue via the mountain pass theorem.
925.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
926.
Rumjanek Victor M. da Costa João Batista N. Echevarria Áurea Cavalcante Márcia F. 《Structural chemistry》2000,11(5):303-306
The room temperature [13C]NMR spectrum of 2,4-bis(N-pyrrolidinyl)-6-chloro-s-triazine shows doubled signals for the pyrrolidine rings, which suggests restricted rotation about the Ar-C—N bond. The rotational barrier around this bond was determined by [13C]dynamic NMR (DNMR) spectra run at different increasing temperatures and also by the PM3 Hamiltonian contained in the MOPAC package. The values thus obtained, 16.6 and 13.6 kcal mol–1, respectively, are in good agreement. 相似文献
927.
Eleonora Erdmann Marcos L. Dias Victor J. R. R. Pita Hugo Destéfanis Fernanda Monasterio Delicia Acosta 《Macromolecular Symposia》2007,258(1):82-89
Summary: Preparation and morphology of high density polyethylene (HDPE)/ polyamide 6 (PA 6)/modified clay nanocomposites were studied. The ability of PA 6 in dispersing clays was used to prepare modified delaminated clays, which were then mixed with HDPE. Mixing was performed using melt processing in a torque rheometer equipped with roller rotors. After etching the materials with boiling toluene and formic acid at room temperature, the morphology was examined by SEM analyses, showing that the PA 6 formed the continuous phase and HDPE the dispersed phase. X-ray diffraction patterns show that the (001) peak of the clay is dramatically decreased and shifted to lower angles, indicating that intercalated/exfoliated nanocomposites are obtained. TEM analyses confirmed the typical structure of exfoliated nanocomposites. A scheme for the mechanism of exfoliation and/or intercalation of these HDPE /PA 6/ /organoclay nanocomposites is proposed. 相似文献
928.
Ernest M. Asani Victor N. Khrustalev Rachel M. Williamson Rodolfo A. Martinez Clifford J. Unkefer Tatiana V. Timofeeva 《Journal of chemical crystallography》2007,37(10):663-667
[1,2,3-13C3]-1-(Phenylsulfinyl)-3-benzyloxyacetone, C16H16O3S, (3) has been synthesized and its crystal structure has been determined by a single-crystal X-ray diffraction analysis. The X-ray diffraction study revealed that compound 3 crystallizes in the monoclinic crystal system in the acentric space group Pc, with cell constants at T = 100 K: a = 16.073(5), b = 5.5079(16), c = 7.949(2) Å, β = 100.221(4)°, V = 692.6(3) Å3, Z = 2, d calc = 1.383 g/cm3. Compound 3 contains the chiral tetravalent three-coordinated sulfur atom, which has a distorted tetrahedral configuration with a lone electron pair occupying one of the tetrahedron vertices. In the crystal, the molecules are packed in stacks along the b axis; the stacks consist of the molecules of the same chirality. Furthermore, the stacks of the molecules of the opposite chirality alternate along the c axis. The molecules in neighboring stacks are arranged by head-to-tail orientations. There are no short intermolecular contacts in the crystal of 3. 相似文献
929.
We set out to efficiently compute the solution of a sequence of linear systems Aixi = bi, where the matrix Ai is tightly related to matrix Ai –1. In the setting of an hp -adaptive Finite Element Method, the sequence of matrices Ai results from successive local refinements of the problem domain. At any step i > 1, a factorization already exists and it is the updated linear system relative to the refined mesh for which a factorization must be computed in the least amount of time. This observation holds the promise of a tremendous reduction in the cost of an individual refinement step. We argue that traditional matrix storage schemes, whether dense or sparse, are a bottleneck, limiting the potential efficiency of the solvers. We propose a new hierarchical data structure, the Unassembled Hyper-Matrix (UHM), which allows the matrix to be stored as a tree of unassembled element matrices, hierarchically ordered to mirror the refinement history of the physical domain. The factorization of such an UHM proceeds in terms of element matrices, only assembling nodes when they need to be eliminated. Efficiency comes in terms of both performance and space requirements. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
930.
Following the optimization approach to brittle fracture, we consider the evolution of a crack in a domain as solution of the global problem of constrained minimization of the total potential energy with respect to both state variables (the displacement vector) and shape variables (parameters of the crack shape). This formulation describes the initiation of a crack in a homogeneous body and its stable as well as unstable propagation, which allows also a kink (topology change) of the crack during the evolution process. By this we assume that contact can occurs between the opposite crack faces. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献