Equation of state of matter at high pressures and temperatures by the modified hartree-fock-slater model

Abstract

The equation of state of matter at extremely high pressures P～ 10–100 Mbars and temperatures T～ 5–50 eV has been very intensively investigated^1,2. The experimental determination of the matter properties in this region of parameters is very expensive, while the theory meets with grave difficulties because the matter under these conditions represents a strongly coupled multicomponent nonideal plasma. In practice, for calculations of the equation of state quasiclassical models are used, as those by Thomas-Fermi (TF) and Thomas-Fenni with corrections3. However, they do not include the shell effects. Most consistently these effects can be taken into account by quantomechanical self-consistent models^4–7     

Three-phase free-water flash calculations using a new Modified Rachford–Rice equation

A novel Modified Rachford–Rice equation is developed for three-phase equilibrium calculations in hydrocarbon–water systems, based on the free-water assumption, i.e., the water-rich liquid phase consists of pure water only. In the inner loop of the flash algorithm, the three-phase problem (consisting in a system of two non-linear equations) is replaced by a pseudo-two-phase problem (consisting in a non-linear equation). Unlike previous formulations, the new Modified Rachford–Rice function is guaranteed to monotonically decrease between two adjacent asymptotes. The negative flash concept is used, and a search window is proposed for the vapor fraction. The new free-water flash method proved to be robust, and excellent agreement between full three-phase flash and pseudo-two-phase free-water flash was obtained for various test problems. The proposed method is very useful in compositional reservoir simulation of certain oil recovery methods and in process simulation.     

Application of conjugate-gradient-like methods to a hyperbolic problem in porous-media flow

This paper presents the application of a preconditioned conjugate-gradient-like method to a non-self-adjoint problem of interest in underground flow simulation. The method furnishes a reliable iterative solution scheme for the non-symmetric matrices arising at each iteration of the non-linear time-stepping scheme. The method employs a generalized conjugate residual scheme with nested factorization as a preconditioner. Model runs demonstrate significant computational savings over direct sparse matrix solvers.     

Ramm积分方程的数值解（Ⅱ）

本文提出了解如下三维的Ramm积分方程的一种新的数值方法:采用带滤子的奇异值分解方法计算上述方程的近似解,并取得了令人满意的数值结果。此外,本文还讨论了解这类积分方程的吉洪诺夫正则方法.     

A NOTE ON QUASI-P RADICAL OF ASSOCIATIVE RINGS

Let P be an arbitrary property of rings and homomorphlcally closed. For an arbitraryring A we construct quasi-P radical O.P(A) with transfinite induction, and give another character-ization of quasi-P radical;     

Propagation of Perturbations of Solutions for a Doubly Degenerate Nonlinear Parabolic Equation

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组合泛函方程

本文旨在提出一些泛函方程,它们当中任何一个的解决不仅对泛函方程理论而且对当今组合计数理论的发展将会产生新的突破。     

A reaction-diffusion model for moderately interacting particles

We consider a nonlinear reaction-diffusion model:n Brownian particles move independently inR ^d and eventually die. The interaction, of binary type, affects only the death rate. The radius of interaction goes to zero as the number of particles increases and we characterize a wide range of speeds at which the radius goes to zero. Within this range we show a law of large numbers for the empirical distributions of the alive particles. The limit is independent of the choice of the speed and it is characterized as the solution of a nonlinear reaction-diffusion equation.     

Analysis of different approaches for evaluation of surface energy of microbial cells by contact angle goniometry

Microbial adhesion on solid substrate is important in various fields of science. Mineral-microbe interactions alter the surface chemistry of the minerals and the adhesion of the bacterial cells to mineral surface is a prerequisite in several biobeneficiation processes. Apart from the surface charge and hydrophobic or hydrophilic character of the bacterial cells, the surface energy is a very important parameter influencing their adhesion on solid surfaces. There were many thermodynamic approaches in the literature to evaluate the cells surface energy. Although contact angle measurements with different liquids with known surface tension forms the basis in the calculation of the value of surface energy of solids, the results are different depending on the approach followed. In the present study, the surface energy of 140 bacterial and seven yeast cell surfaces has been studied following Fowkes, Equation of state, Geometric mean and Lifshitz-van der Waals acid-base (LW-AB) approaches. Two independent issues were addressed separately in our analysis. At first, the surface energy and the different components of the surface energy for microbial cells surface are examined. Secondly, the different approaches are evaluated for their internal consistency, similarities and dissimilarities. The Lifshitz-van der Waals component of surface energy for most of the microbial cells is realised to be approximately 40 mJ/m2 +/-10%. Equation of state and Geometric mean approaches do not possess any internal consistency and yield different results. The internal consistency of the LW-AB approach could be checked only by varying the apolar liquid and it evaluates coherent surface energy parameters by doing so. The electron-donor surface energy component remains exactly the same with the change of apolar liquid. This parameter could differentiate between the Gram-positive and Gram-negative bacterial cells. Gram-negative bacterial cells having higher electron-donor parameter had lower nitrogen, oxygen and phosphorous content on their cell surfaces. Among the four approaches, LW-AB was found to give the most consistent results. This approach provides more detailed information about the microbial cell surface and the electron-donor parameter differentiates different type of cell surfaces.     

INVESTIGATIONS ON VINYLENE CARBONATE Ⅰ. PREPARATION AND PROPERTIES OF POLY-(VINYLENEC ARBONATE)

Bulk polymerization of vinylene carbonate using t-butylperoxypivalate at 40℃gave colourless, high molecular weight poly(vinylene carbonate) (PVCA). Solutions of PVCA in acetone and DMF are not stable at 25℃and this degradation was studied. From measurements in DMF with unfractionated PVCA a Mark-Houwink equation was obtained: