Thermoelectric spin diffusion in a ferromagnetic metal

We present a semiclassical theory of spin diffusion in a ferromagnetic metal subject to a temperature gradient. Spin-flip scattering can generate pure thermal spin currents by short-circuiting spin channels while suppressing spin accumulations. A thermally induced spin density is locally generated when the energy dependence of the density of states is spin polarized.     

Computing Orbits of the Automorphism Group of the Subsequence Poset B m,n

Let B _m,n denote the set of all words obtained from the cyclic word of length n on an alphabet of m letters in by deleting on all possible ways and their natural order. In [Order, 16: 179–194, 1999] Burosch et al. computed the automorphism group of the poset B _m,n . In this paper, we apply this result to obtain all of orbits of the natural action of Aut(B _m,n ) on B _m,n .     

Finite‐volume‐type VOF method on dynamically adaptive quadtree grids

This paper describes a finite‐volume volume‐of‐fluid (VOF) method for simulating viscous free surface flows on dynamically adaptive quadtree grids. The scheme is computationally efficient in that it provides relatively fine grid resolution at the gas–liquid interface and coarse grid density in regions where flow variable gradients are small. Special interpolations are used to ensure volume flux conservation where differently sized neighbour cells occur. The numerical model is validated for advection of dyed fluid in unidirectional and rotating flows, and for two‐dimensional viscous sloshing in a rectangular tank. Copyright © 2004 John Wiley & Sons, Ltd.     

Operational risk modelling and organizational learning in structured finance operations: a Bayesian network approach

This paper describes the development of a tool, based on a Bayesian network model, that provides posteriori predictions of operational risk events, aggregate operational loss distributions, and Operational Value-at-Risk, for a structured finance operations unit located within one of Australia's major banks. The Bayesian network, based on a previously developed causal framework, has been designed to model the smaller and more frequent, attritional operational loss events. Given the limited availability of risk factor event information and operational loss data, we rely on the elicitation of subjective probabilities, sourced from domain experts. Parameter sensitivity analysis is performed to validate and check the model's robustness against the beliefs of risk management and operational staff. To ensure that the domain's evolving risk profile is captured through time, a formal approach to organizational learning is investigated that employs the automatic parameter adaption features of the Bayesian network model. A hypothetical case study is then described to demonstrate model adaption and the application of the tool to operational loss forecasting by a business unit risk manager.     

Investigating the effect of heat treatment on hydrogen permeation behavior of API X-70 steel

Pipeline steels absorb different amounts of hydrogen during transportation of sour oil and gas. Since hydrogen-related damages such as hydrogen-induced cracking are strongly affected by hydrogen permeation behavior of steels, the purpose of this study determined to investigate hydrogen permeation behavior in API X-70 pipeline steel using electrochemical permeation method. The effect of heat treatment was also considered. It was found that hydrogen diffusivity increased by annealing the X-70 and it was decreased by normalizing. The condition was reverse for hydrogen apparent solubility. Finally, it was concluded that change in hydrogen diffusivity can be attributed to changes in grain size due to heat treatment.     

Remarks on the Wiener index of unicyclic graphs

Unicyclic graphs are connected graphs with the same number of vertices and edges. Tang and Deng (J. Math. Chem. 43:60–74, 2008) considered the problem of classification of all unicyclic graphs with the first three smallest and largest Wiener indices. In this paper, by construction of some classes of unicyclic graphs, the classification of unicyclic graphs with the first three maximum and minimum Wiener indices is completed.     

Investigating the Temperature Dependency of Oil and Water Relative Permeabilities for Heavy Oil Systems

A look into the literature on the temperature dependency of oil and water relative permeabilities reveals contradictory reports. There are some publications reporting shifts in the water saturation range as well as variations in the relative permeability curves by temperature. On the other hand, some authors have blamed the experimental artifacts, viscous instabilities and fingering issues for these variations. We have performed core flooding experiments to further investigate this issue. Glass bead packs and sand packs were used as the porous media, and Athabasca bitumen with varying viscosities was displaced by hot water at differing temperatures. The unsteady-state method of relative permeability measurement was applied and the experimental data were history matched by a simulator that is tailor made to predict the relative permeabilities. The matches were obtained by varying the relative permeability correlation parameters. The results indicated that the initial water saturation has a direct relation with temperature, while residual oil saturation generally drops at higher temperatures. Although the water saturation range shifts, no direct and unique trend for either oil or water relative permeability is justified. The spread in relative permeabilities especially in the case of higher permeable cores suggests that viscous instabilities are present. As the same saturation shift happens by only changing the oil viscosity, the relative permeability variations with temperature can be attributed to oil to water viscosity ratio changes with temperature. Temperature dependency of relative permeabilities is more related to experimental artifacts, viscous fingering and viscosity changes than fundamental flow properties.     

Damping in a Squeezed Bath and Its Time Evolution through the Complete Class of Gaussian Quasi-Distributions

By virtue of the thermo-entangled states representation of the density operator and using the dissipative interaction picture, we solve the master equation of a driven damped harmonic oscillator in a squeezed bath. We show that the essential part of the dynamics can be expressed by the convolution of the initial Wigner function with a special kind of normalized Gaussian in the phase space and relate the dynamics with the change of Gaussian ordering of the density operator.