Transmission of Dirac Electrons Through Graphene Multilayers with Gaussian Profile

2012 ◽  
Vol 1371 ◽  
Author(s):  
J. A. Aguilar-Hernández ◽  
J. Madrigal-Melchor ◽  
J. C. Martínez-Orozco ◽  
I. Rodríguez-Vargas
Keyword(s):  
Graphene Sheet ◽  
Gaussian Distribution ◽  
Matrix Method ◽  
Stop Band ◽  
Angle Of Incidence ◽  
Gaussian Profile ◽  
Number Of Layers ◽  
T Matrix ◽  
The Difference ◽  
Maximum Minimum

ABSTRACTIn this work, we use the T-matrix method to study the tunneling of Dirac electrons through graphene multilayers. A graphene sheet is deposited on top of slabs of SiO2-SiC substrates, of which we applied a Gaussian distribution in the size width of the SiC substrate. We calculate the transmittance as a function of energy for different incident angles and different number of layers of the Gaussian distribution. We obtain different stop-band regions. These regions are wider when the width of the barrier is increased. Furthermore, it is possible to tune the width and the position of stop-band with the angle of incidence, the σ value of the Gaussian distribution, and the difference between the maximum-minimum sizes of the barrier.

Seismogram synthesis for multi-layered media with irregular interfaces by global generalized reflection/transmission matrices method. I. Theory of two-dimensional SH case

1990 ◽  
Vol 80 (6A) ◽  
pp. 1696-1724 ◽  
Author(s):  
Xiao-fei Chen
Keyword(s):  
Matrix Method ◽  
Computation Time ◽  
Source Area ◽  
Layered Media ◽  
Two Dimensional ◽  
Finite Frequency ◽  
Number Of Layers ◽  
Efficient Scheme ◽  
T Matrix ◽  
Irregular Topography

Abstract In this paper, we present a new method of seismogram synthesis for multi-layered media with irregular interfaces due to an arbitrary source. This method can be viewed as either an extension of the T matrix method for an inclusion to multi-layered media by introducing the global generalized R/T matrices, or an extension of the generalized R/T coefficients method for horizontally layered media to irregular layered ones by incorporating the T matrix method. The formulation obtained in this paper is expressed in terms of the global generalized R/T matrices. These global generalized R/T matrices can be determined from integrals along each interface and integral over source area via a recursive relation. This formulation provides an efficient scheme of computation, especially when the number of layers increases. Also, this formulation can be applied to any finite frequency, although for higher frequency it needs more computation time than for lower frequency. As examples, we give solutions of three specific problems, namely, horizontally layered media, irregular topography, and an irregular layer over a half-space.

Effect of Flaw Dimensions on Ductile Fracture Behavior of Non-Aligned Multiple Flaws in a Plate

2011 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito
Keyword(s):  
Ductile Fracture ◽  
Flat Plate ◽  
Fracture Behavior ◽  
Maximum Load ◽  
Surface Flaws ◽  
Fracture Tests ◽  
The Difference ◽  
Almost All ◽  
Maximum Minimum

The fitness-for-service codes require the characterization of non-aligned multiple flaws for flaw evaluation, which is performed using a flaw proximity rule. Worldwide, almost all such codes provide their own proximity rule, often with unclear technical bases of the application of proximity rule to ductile or fully plastic fracture. In particular, the effect of flaw dimensions of multiple surface flaws on fully plastic fracture of non-aligned multiple flaws had not been clear. To clarify the effect of the difference of part through-wall and through-wall flaws on the behavior of fully plastic fracture, the fracture tests of flat plate specimens with non-aligned multiple part through-wall flaws were conducted. When the flaw depth a was shallow with 0.4 in ratio of a to thickness t, the maximum load Pmax occurred at penetration of multiple flaws and the effect of vertical distance of non-aligned multiple flaws H on Pmax was not so significant. However, when flaw depth was deep with 0.8 in a/t, Pmax occurred after penetration of flaws and the effect of H on Pmax could be seen clearly. It was judged that the through-wall flaw tests were appropriate for discussion of the effect of H on Pmax and the alignment rule of multiple flaws. In addition, in order to clarify the appropriate length parameter to estimate Pmax of test specimens with dissimilar non-aligned through-wall multiple flaws, the fracture tests of plate specimens were also conducted. The effect of different flaw length on Pmax was discussed with maximum, minimum and averages of dissimilar non-aligned multiple flaw lengths. Experimental results showed that the maximum length lmax would be an appropriate length parameter to estimate Pmax, when the non-aligned multiple through-wall flaws were dissimilar.

45° REFLECTOMETRY OF SEMICONDUCTOR QUANTUM WELLS

2001 ◽  
Vol 15 (17n19) ◽  
pp. 683-687
Author(s):  
A. SILVA-CASTILLO ◽  
F. PEREZ-RODRIGUEZ
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Growth Direction ◽  
Angle Of Incidence ◽  
Near Surface ◽  
New Information ◽  
Difference Formula ◽  
Exciton Polaritons ◽  
The Difference ◽  
First Time

We have applied the 45° reflectometry for the first time to study exciton-polaritons in quantum wells. The 45° reflectometry is a new polarization-modulation technique, which is based on the measurement of the difference [Formula: see text] between the p-polarization reflectivity (Rp) and the squared s-polarization reflectivity [Formula: see text] at an angle of incidence of 45°. We show that [Formula: see text] spectra may provide qualitatively new information on the exciton-polariton modes in a quantum well. These optical spectra turn out to be very sensitive to the zeros of the dielectric function along the quantum-well growth direction and, therefore, allow to identify the resonances associated with the Z exciton-polariton mode. We demonstrate that 45° reflectometry could be a powerful tool for studying Z exciton-polariton modes in near-surface quantum wells, which are difficult to observe in simple spectra of reflectivity Rp

scholarly journals Numerically efficient version of the T-matrix method

2001 ◽  
Vol 80 (3-4) ◽  
pp. 385-393 ◽  
Author(s):  
A.G. Ramm
Keyword(s):  
Matrix Method ◽  
T Matrix

scholarly journals Convergence of the iterative T-matrix method

2020 ◽  
Vol 28 (19) ◽  
pp. 28269
Author(s):  
Michael Kahnert ◽  
Tom Rother
Keyword(s):  
Matrix Method ◽  
T Matrix

scholarly journals The Influence of a Vitrectomy on the Diurnal Intraocular Pressure

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yong Woo Lee ◽  
Joon Mo Kim ◽  
Seong Hee Shim ◽  
Da Yeong Kim ◽  
Jeong Hun Bae ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Diurnal Fluctuation ◽  
Age And Gender ◽  
History Of ◽  
The Difference ◽  
And Gender ◽  
Diurnal Iop ◽  
Maximum Minimum ◽  
Normal Controls ◽  
Healthy Eyes

Purpose. To evaluate the diurnal intraocular pressure (IOP) in eyes after vitrectomy compared to that of healthy eyes.Methods. Twenty-one patients who had undergone vitrectomy and 21 age- and gender-matched normal controls were enrolled during the same period. We measured the diurnal IOP every two hours between 9 a.m. and 11 p.m. in all patients who were admitted for cataract surgery. Patients with a history of eye surgery (not including vitrectomy) or use of a medication that is associated with IOP were excluded. The IOP and ocular parameters of patients were compared with the same patients’ fellow healthy eyes and with normal eyes of age- and gender-matched controls.Results. There were no significant differences between vitrectomized eyes and normal fellow eyes with regard to all IOP parameters including the maximum, minimum, and IOP fluctuation values. Diurnal fluctuation of IOP (or the difference between the maximum and minimum IOP) was larger in vitrectomized eyes than it was in age- and gender-matched control eyes.Conclusions. Vitrectomy did not markedly affect the IOP. Although there were no severe complications after vitrectomy, the IOP fluctuation was wider in vitrectomized eyes than it was in normal eyes.

Aerodynamic Data for Two Variants of Root Turbine Blade Sections for a 54″ Turbine Rotor Blade

2014 ◽  
Author(s):  
David Šimurda ◽  
Martin Luxa ◽  
Pavel Šafařík ◽  
Jaroslav Synáč ◽  
Bartoloměj Rudas
Keyword(s):  
Limit Load ◽  
Axial Direction ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Angle Of Incidence ◽  
Flow Angle ◽  
Turbine Rotor Blade ◽  
Blade Cascade ◽  
The Difference ◽  
Kinetic Energy Loss

Aerodynamic investigations were performed on planar blade cascades representing two alternative root sections of rotor blades 54″ in length with straight fir-tree root. Each of the variants was designed for different number of blades in the rotor. This paper presents the results of measurements showing the dependency of the kinetic energy loss coefficient and the exit flow angle on the exit isoentropic Mach number and the angle of incidence. Images of the flow fields are also presented. The experimental data is analyzed to assess and document the difference between the two root section designs. Results show that requirement of straight fir tree root leading to high design incidence angles significantly limit operation range. Also in case of root sections with high exit Mach numbers a limit load conditions are an issue. In order to utilize available pressure drop blade cascade throat/pitch ratios should be kept as high as possible which favorites variant with lower number of blades and higher outlet metal angle (relative to axial direction).

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