In this study, we numerically investigated the transient steady state for the problem of double-diffusive convection in porous triangular enclosures with the effects of thin fin, various thermal and concentration boundary conditions in the presence of heat source. Finite difference method was employed to solve the dimensionless governing equations of the problem. The effects of governing parameters, namely heat generation parameter, buoyancy parameter and Lewis number on the streamlines, temperature and concentration contours as well as selected velocity component in the x-direction, Nusselt and Sherwood numbers and average Nusselt and Sherwood numbers at the enclosure bottom wall in the case of fixed boundary conditions and the case various boundary conditions were considered. The present results are validated by favorable comparisons with previously published results. All the results are presented in graphical and tabular forms and discussed.

A numerical investigation of unsteady magnetohydrodynamic free convection in an inclined square cavity filled with a fluid-saturated porous medium and with internal heat generation has been performed. A uniform magnetic field inclined with the same angle of the inclination of the cavity is applied. The governing equations are formulated and solved by a direct explicit finite-difference method subject to appropriate initial and boundary conditions. A parametric study illustrating the influence of the Hartmann number, Rayliegh number and the inclination angle of the cavity on the flow and heat transfer characteristics such as the streamlines, isotherms and the Nusselt number is performed. The velocity components at mid section of the cavity as well as the temperature profiles are reported graphically. The values of Nusselt number for various parametric conditions are presented in tabular form.

The problem of double-diffusive convection in inclined finned triangular porous enclosures for various thermal and concentration boundary conditions and in the presence of heat source or sink was studied. The finite difference method was employed to solve the dimensionless governing equations of the problem. The effects of the governing parameters, namely the dimensionless time parameter, the inclination angle, Darcy number, heat generation/absorption parameter, the buoyancy parameter and the Rayleigh number on the streamlines, temperature and concentration contours as well as selected velocity component in the x-direction, local and average Nusselt numbers and local and average Sherwood number at the heated and concentrated wall for various values of the aspect ratio and the position of the fin were considered. The present results are validated by favorable comparisons with previously published results. All the results of the problem were presented in graphical and tabular forms and discussed.

Continuum equations governing thermal non-equilibrium modeling of steady natural convection inside wavy enclosures with the effect of thermal radiation are developed. These equations account for such effects as the inter-phase heat transfer coefficient effect, the thermal radiation effect, the modified conductivity ratio effect and the Rayleigh number effect. Finite difference method is employed to solve these equations and comparisons between previous published works are presented. Numerical results for the flow and heat transfer for the fluid and solid phases are obtained for various combinations of the physical parameters. Graphical and tabular results illustrating interesting features of the physics of the problem are presented and discussed.

Bulk chalcogenide Ge20Se80−xTex (where x = 0, 10, 20 and 30 at.%) glasses were prepared using the meltquench technique. The total structure factors of these alloys are obtained from the X-ray scattering data in the momentum transfer interval 0.61≤K≤16.45 ˚A−1. From reverse Monte Carlo (RMC) simulations of the X-ray scattering data, the short and intermediate-range order parameters are obtained. The simulations are useful to compute the partial pair distribution functions, gij(r), and the partial structure factors, Sij(K). In Te-rich glass, the first sharp diffraction peak (FSDP) appears as a shoulder, instead of a peak for others, confirms that Se–Se bonds in addition to Ge–Ge bonds are responsible for the intermediate-range order inside these glasses. The partial coordination numbers and the bond angle distributions within the first coordination shell have been calculated. The ratio of the first to second peak positions (r1/r2) and the corresponding bond angle (theta) have confirmed that the Ge(Se1/2)4 tetrahedra, connected by Se–Se chains, can be considered as the main building units inside the investigated glasses.

Bulk chalcogenide Ge20Se80−xTex (where x = 0, 10, 20 and 30 at.%) glasses were prepared using the meltquench technique. The total structure factors of these alloys are obtained from the X-ray scattering data in the momentum transfer interval 0.61≤K≤16.45 ˚A−1. From reverse Monte Carlo (RMC) simulations of the X-ray scattering data, the short and intermediate-range order parameters are obtained. The simulations are useful to compute the partial pair distribution functions, gij(r), and the partial structure factors, Sij(K). In Te-rich glass, the first sharp diffraction peak (FSDP) appears as a shoulder, instead of a peak for others, confirms that Se–Se bonds in addition to Ge–Ge bonds are responsible for the intermediate-range order inside these glasses. The partial coordination numbers and the bond angle distributions within the first coordination shell have been calculated. The ratio of the first to second peak positions (r1/r2) and the corresponding bond angle (theta) have confirmed that the Ge(Se1/2)4 tetrahedra, connected by Se–Se chains, can be considered as the main building units inside the investigated glasses.

Amorphous GexSe100−x (with x=10, 20 and 40 at%) alloys were prepared using the melt–quench technique. Two-dimensional Monte Carlo of the total pair distribution functions (MCGR) have been found and used to assemble the three-dimensional atomic configurations using the reverse Monte Carlo (RMC) method. The simulations are useful to compute the partial pair distribution functions and the partial structure factors of the studied glasses. The partial pair distribution functions indicate that the basic building units are GeSe4 and Ge2Se6 tetrahedral units in the Se-rich and Ge-rich glasses, respectively. Some of these tetrahedral units are connected by the homopolar units as confirmed by the bond angle distribution functions. The partial structure factors have shown that not only the homopolar Ge–Ge bonds, but also Se–Se bonds are behind the appearance of the first sharp diffraction peak (FSDP) in the total structure factor.

Amorphous GexSe100−x (with x=10, 20 and 40 at%) alloys were prepared using the melt–quench technique. Two-dimensional Monte Carlo of the total pair distribution functions (MCGR) have been found and used to assemble the three-dimensional atomic configurations using the reverse Monte Carlo (RMC) method. The simulations are useful to compute the partial pair distribution functions and the partial structure factors of the studied glasses. The partial pair distribution functions indicate that the basic building units are GeSe4 and Ge2Se6 tetrahedral units in the Se-rich and Ge-rich glasses, respectively. Some of these tetrahedral units are connected by the homopolar units as confirmed by the bond angle distribution functions. The partial structure factors have shown that not only the homopolar Ge–Ge bonds, but also Se–Se bonds are behind the appearance of the first sharp diffraction peak (FSDP) in the total structure factor.

Some aspects of the irreversible dynamics of a generalized Jaynes– Cummings model are addressed. By working in the dressed-state representation, it is possible to split the dynamics of the entanglement and coherence. The exact solution of the master equation in the case of a high-Q cavity with atomic decay is found. Effects of the atomic spontaneous decay on the temporal evolution of partial entropies of the atom or the field and the total entropy as a quantitative measure entanglement are elucidated. The degree of entanglement, through the sum of the negative eigenvalues of the partially transposed density matrix and the negative mutual information has been studied and compared with other measures.

Some aspects of the irreversible dynamics of a generalized Jaynes– Cummings model are addressed. By working in the dressed-state representation, it is possible to split the dynamics of the entanglement and coherence. The exact solution of the master equation in the case of a high-Q cavity with atomic decay is found. Effects of the atomic spontaneous decay on the temporal evolution of partial entropies of the atom or the field and the total entropy as a quantitative measure entanglement are elucidated. The degree of entanglement, through the sum of the negative eigenvalues of the partially transposed density matrix and the negative mutual information has been studied and compared with other measures.