Alireza Heidari

Unsteady Magnetohydrodynamic Heat Transfer in a Semi-Infinite Porous Medium with Thermal Radiation Flux: Analytical and Numerical Study

The unsteady, buoyancy-induced, hydromagnetic, thermal convection flow in a semi-infinite porous regime adjacent to an infinite hot vertical plate moving with constant velocity, is studied in the presence of significant thermal radiation. The momentum and energy conservation equations are normalized and then solved using both the Laplace transform technique and Network Numerical Simulation. Excellent agreement is obtained between both analytical and numerical methods. An increase in Hartmann number (𝑀2) strongly decelerates the flow and for very high strength magnetic fields (𝑀2=20), the flow is reversed after a short time interval. The classical velocity overshoot is also detected close to the plate surface for low to intermediate values of 𝑀2 at both small and large times; however this overshoot vanishes for larger strengths of the transverse magnetic field (𝑀2=10). An increase in radiation-conduction parameter (𝐾𝑟) significantly increases temperature throughout the porous regime at both small and larger times, adjacent to the plate, but decreases the shear stress magnitudes at the plate. Temperature gradient is reduced at the plate surface for all times, with a rise in radiation-conduction parameter (𝐾𝑟). Shear stress is reduced considerably with an increase in Darcian drag parameter (𝐾𝑝).

Flux Dynamics in Y358 Superconductors

Thermally activated flux motion and specific electric resistance in Y358 were studied under different magnetic fields ranging from 0 to 15 kOe. Through investigating the broadening of normal-superconducting transition, we found that the thermally-activated-flux-motion model can describe the electronic effect near the superconducting transition temperature. By modifying this model, specific electric resistance at different magnetic fields was calculated.

Study of the vibrational characteristics of the homonuclear diatomic nuclear schrödinger equation with a numerov method using a number of empirical potential functions

Many empirical potential energy functions have been modeled to represent the potential energy function of a diatomic molecule along whole range of internuclear distance coordinate, whereby one can determine certain molecular constants. Here we employ various potential functions such as Morse, Rydberg, Varshni(II), Varshni(III), Varshni(VI), Pöschl-Teller, Hulburt-Hirschfelder, Lippincott, Frost-Musulin, Linnet, and Rosen-Morse, and the Numerov method to solve the nuclear Schrödinger equation for F2, as an example of a homonuclear diatomic molecule. Herewith, the vibrational and vibration-rotation energy levels are obtained and excellent accuracy is achieved. The potential of employing the Numerov method in engineering physics computations is emphasized.

A New Approach to the Characteristics and Short-Channel Effects of Double-Gate Carbon Nanotube Field-Effect Transistors using MATLAB: A Numerical Study

In this paper, first, the impact of different gate arrangements on the short-channel effects of carbon nanotube field-effect transistors with doped source and drain with the self-consistent solution of the three-dimensional Poisson equation and the Schr¨odinger equation with open boundary conditions, within the non-equilibrium Green function, is investigated. The results indicate that the double-gate structure possesses a quasi-ideal subthreshold oscillation and an acceptable decrease in the drain induced barrier even for a relatively thick gate oxide (5 nm). Afterward, the electrical characteristics of the double-gate carbon nanotube field-effect transistors (DG-CNTFET) are investigated. The results demonstrate that an increase in diameter and density of the nanotubes in the DG-CNTFET increases the on-state current. Also, as the drain voltage increases, the off-state current of the DG-CNTFET decreases. In addition, regarding the negative gate voltages, for a high drain voltage, increasing in the drain current due to band-to-band tunnelling requires a larger negative gate voltage, and for a low drain voltage, resonant states appear

A Novel Analytical Approach to Superconductivity in Single-Walled Carbon Nanotubes Using the Green's Function: A Mathematical Study

The editorial board announced this article has been retracted on January 4, 2013. If you have any further question, please contact us at: jmr@ccsenet.org

Study of Structure and Properties of Cadmium-oxide-doped YBa2Cu3O7–delta Superconductor Using XRD Patterns: A Numerical Investigation

The editorial board announced that this article has been retracted on December 31, 2012. If you have any further question, please contact us at: ijc@ccsenet.org

A New Approach to Decoherence Effects of Spontaneous Emission and Cavity Dissipation on Stimulated Raman Adiabatic Passage in an Optical Cavity: A Computational Study

The editorial board announced that this article has been retracted on January 4, 2013. If you have any further question, please contact us at: apr@ccsenet.org