scholarly journals Electronic properties of α − 𝒯3 quantum dots in magnetic fields

2020 ◽  
Vol 93 (9) ◽  
Author(s):  
Alexander Filusch ◽  
Holger Fehske
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Quantum Dot ◽  
Electronic Properties ◽  
Local Density ◽  
Tight Binding ◽  
Long Wavelength ◽  
Infinite Mass ◽  
Long Wavelength Approximation ◽  
Wavelength Approximation

Abstract We address the electronic properties of quantum dots in the two-dimensional α − 𝒯3 lattice when subjected to a perpendicular magnetic field. Implementing an infinite mass boundary condition, we first solve the eigenvalue problem for an isolated quantum dot in the low-energy, long-wavelength approximation where the system is described by an effective Dirac-like Hamiltonian that interpolates between the graphene (pseudospin 1/2) and Dice (pseudospin 1) limits. Results are compared to a full numerical (finite-mass) tight-binding lattice calculation. In a second step we analyse charge transport through a contacted α − 𝒯3 quantum dot in a magnetic field by calculating the local density of states and the conductance within the kernel polynomial and Landauer-Büttiker approaches. Thereby the influence of a disordered environment is discussed as well. Graphical abstract

scholarly journals Effect of a Steady Flow and an Atmospheric Magnetic Field on the Solar p- and f-Modes

2001 ◽  
Vol 203 ◽  
pp. 208-210 ◽  
Author(s):  
R. Erdélyi ◽  
Y. Taroyan
Keyword(s):  
Magnetic Field ◽  
Simple Model ◽  
Uniform Magnetic Field ◽  
The Sun ◽  
Equilibrium Flow ◽  
Frequency Shifts ◽  
Homogeneous Flow ◽  
Long Wavelength ◽  
Long Wavelength Approximation ◽  
Wavelength Approximation

The combined effect of a subsurface steady homogeneous flow and a chromospheric uniform magnetic field on the solar p- and f-modes is evaluated theoretically for a simple model of the Sun. The derived dispersion relation is solved analytically in limit of the long wavelength approximation and is evaluated numerically for arbitrary wavelengths. The influence of an equilibrium flow is more dominant in limit of small wavenumbers. For arbitrary wavelengths the effect of a magnetic field might be stronger than frequency shifts caused by a steady homogeneous flow.

HEAT TRANSFER IN A SLIP FLOW OF PERISTALTIC TRANSPORT OF A MAGNETO-NEWTONIAN FLUID THROUGH A POROUS MEDIUM

2009 ◽  
Vol 02 (03) ◽  
pp. 299-309 ◽  
Author(s):  
AYMAN MAHMOUD SOBH
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Porous Medium ◽  
Slip Flow ◽  
Transverse Magnetic ◽  
Physical Parameters ◽  
Long Wavelength ◽  
Governing System ◽  
Long Wavelength Approximation ◽  
Wavelength Approximation

In this paper, we study the interaction of peristalsis with heat transfer for the flow of a viscous fluid through a porous medium in uniform and nonuniform channels. The flow is subjected to constant transverse magnetic field. Long wavelength approximation (that is, the wavelength of the peristaltic wave is large compared with the radius of the channel) is used to solve the governing system. Closed form expressions are derived for the pressure–flow relationship, temperature, and heat transfer coefficient. The effects of various physical parameters are discussed through graphs.

Magnetohydrodynamic Flow of a Carreau Fluid in a Channel with DifferentWave Forms

2011 ◽  
Vol 66 (3-4) ◽  
pp. 215-222 ◽  
Author(s):  
Tasawar Hayat ◽  
Najma Saleem ◽  
Said Mesloub ◽  
Nasir Ali
Keyword(s):  
Magnetic Field ◽  
Peristaltic Motion ◽  
Carreau Fluid ◽  
Long Wavelength ◽  
Electrically Conducting ◽  
Long Wavelength Approximation ◽  
Wave Forms ◽  
Wavelength Approximation ◽  
Fluid Behaviour ◽  
Pumping And Trapping

In this investigation, we discuss the peristaltic motion based on the constitutive equations of a Carreau fluid in a channel. The fluid is electrically conducting in the presence of a uniform applied magnetic field. Four different wave forms are chosen. The fluid behaviour is studied using long wavelength approximation. Detailed analysis is performed for various emerging parameters on pumping and trapping phenomena. The present results reduce favourably with the currently available results of hydrodynamic case when the Hartman number is chosen zero.

Peristaltic thrusting of a thermal-viscosity nanofluid through a resilient vertical pipe

2020 ◽  
Vol 75 (8) ◽  
pp. 727-738 ◽  
Author(s):  
Ramzy M. Abumandour ◽  
Islam M. Eldesoky ◽  
Mohamed H. Kamel ◽  
Mohamed M. Ahmed ◽  
Sara I. Abdelsalam
Keyword(s):  
Pressure Gradient ◽  
Hartmann Number ◽  
Amplitude Ratio ◽  
Variable Viscosity ◽  
Friction Forces ◽  
Long Wavelength ◽  
Viscosity Parameter ◽  
Long Wavelength Approximation ◽  
Wavelength Approximation ◽  
Theoretical Results

AbstractIn the article, the effects of the thermal viscosity and magnetohydrodynamic on the peristalsis of nanofluid are analyzed. The dominant neutralization is deduced through long wavelength approximation. The analytical solution of velocity and temperature is extracted by using steady perturbation. The pressure gradient and friction forces are obtained. Numerical results are calculated and contrasted with the debated theoretical results. These results are calculated for various values of Hartmann number, variable viscosity parameter and amplitude ratio. It is observed that the pressure gradient is reduced with an increase in the thermal viscosity parameter and that the Hartmann number enhances the pressure difference.

Interaction of a conjugated polyaromatic molecule with a single dangling bond quantum dot on a hydrogenated semiconductor

2016 ◽  
Vol 18 (5) ◽  
pp. 3854-3861 ◽  
Author(s):  
Szymon Godlewski ◽  
Marek Kolmer ◽  
Mads Engelund ◽  
Hiroyo Kawai ◽  
Rafal Zuzak ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electronic Properties ◽  
Dangling Bond

Starphene molecules are weakly attached to single dangling bond quantum dots, retaining the unperturbed originally designed electronic properties.

Tensile Stability of Medial Arterial Tissues

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Alan J. Levy ◽  
Xinyu Zhang
Keyword(s):  
Smooth Muscle ◽  
Constitutive Models ◽  
Constitutive Parameter ◽  
Axial Stretch ◽  
Long Wavelength ◽  
Arterial Tissue ◽  
Long Wavelength Approximation ◽  
Geometrical Imperfections ◽  
Wavelength Approximation ◽  
Nominal Load

Tensile stability of healthy medial arterial tissue and its constituents, subject to initial geometrical and/or material imperfections, is investigated based on the long wavelength approximation. The study employs existing constitutive models for elastin, collagen, and vascular smooth muscle which comprise the medial layer of large elastic (conducting) arteries. A composite constitutive model is presented based on the concept of the musculoelastic fascicle (MEF) which is taken to be the essential building block of medial arterial tissue. Nonlinear equations governing axial stretch and areal stretch imperfection growth quantities are obtained and solved numerically. Exact, closed-form results are presented for both initial and terminal rates of imperfection growth with nominal load. The results reveal that geometrical imperfections, in the form of area nonuniformities, and material imperfections, in the form of constitutive parameter nonuniformities, either decrease or increase only slightly with increasing nominal load; a result which is to be expected for healthy tissue. By way of contrast, an examination of a simple model for elastin with a degrading stiffness gives rise to unbounded imperfection growth rates at finite values of nominal load. The latter result indicates how initial geometrical and material imperfections in diseased tissues might behave, a topic of future study by the authors.

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