Volume 67, Issue 6-7

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

The use of substitution boxes (S-boxes) in encryption applications has proven to be an effective nonlinear component in creating confusion and randomness. The S-box is evolving and many variants appear in literature, which include advanced encryption standard (AES) S-box, affine power affine (APA) S-box, Skipjack S-box, Gray S-box, Lui J S-box, residue prime number S-box, Xyi S-box, and S 8 S-box. These S-boxes have algebraic and statistical properties which distinguish them from each other in terms of encryption strength. In some circumstances, the parameters from algebraic and statistical analysis yield results which do not provide clear evidence in distinguishing an S-box for an application to a particular set of data. In image encryption applications, the use of S-boxes needs special care because the visual analysis and perception of a viewer can sometimes identify artifacts embedded in the image. In addition to existing algebraic and statistical analysis already used for image encryption applications, we propose an application of root mean square error technique, which further elaborates the results and enables the analyst to vividly distinguish between the performances of various S-boxes. While the use of the root mean square error analysis in statistics has proven to be effective in determining the difference in original data and the processed data, its use in image encryption has shown promising results in estimating the strength of the encryption method. In this paper, we show the application of the root mean square error analysis to S-box image encryption. The parameters from this analysis are used in determining the strength of S-boxes

By applying the micropolar fluid model of Eringen (J. Math. Mech. 16, 1 (1966) and Int. J. Mech. Sci. 31, 605 (1993)), the squeeze film lubrication problems between conical plates are extended in the present paper. A non-Newtonian modified Reynolds equation is derived and applied to obtain the solution of squeeze film characteristics. Comparing with the traditional Newtonian case, the non-Newtonian effects of micropolar fluids are found to enhance the load capacity and lengthen the approaching time of conical plates. Some numerical results are also provided in tables for engineer applications

We construct four types of analytical soliton solutions for the higher-order nonlinear Schrödinger equation with distributed coefficients. These solutions include bright solitons, dark solitons, combined solitons, and M-shaped solitons. Moreover, the explicit functions which describe the evolution of the width, peak, and phase are discussed exactly.We finally discuss the nonlinear soliton tunnelling effect for four types of femtosecond solitons

New positon, negaton, and complexiton solutions of a coupled Korteweg-de Vries - modified Korteweg-de Vries system are constructed directly from the zero seed solution by means of Darboux transformation with different constant selection. The positon, negaton, and complexiton solutions are given out analytically and graphically

The physical science importance of the Cauchy problem of the reaction-diffusion equation appears in the modelling of a wide variety of nonlinear systems in physics, chemistry, ecology, biology, and engineering. A hybrid of Fourier transform and Adomian decomposition method (FTADM) is developed for solving the nonlinear non-homogeneous partial differential equations of the Cauchy problem of reaction-diffusion. The results of the FTADM and the ADM are compared with the exact solution. The comparison reveals that for the same components of the recursive sequences, the errors associated with the FTADM are much lesser than those of the ADM. We show that as time increases the results of the FTADM approaches 1 with only six recursive terms. This is in agreement with the physical property of the density-dependent nonlinear diffusion of the Cauchy problem which is also in agreement with the exact solution. The monotonic and very rapid convergence of the results of the FTADM towards the exact solution is shown to be much faster than that of the ADM

Boundary layer equations are derived for the first time for a Williamson fluid. Using Lie group theory, a symmetry analysis of the equations is performed. The partial differential system is transferred to an ordinary differential system via symmetries, and the resulting equations are numerically solved. Finally, the effects of the non-Newtonian parameters on the solutions are discussed

To enhance the efficiency of eavesdropping detection in the quantum secure direct communication protocol, an improved quantum secure direct communication protocol based on a four-particle Green-Horne-Zeilinger (GHZ) state is presented. In the protocol, the four-particle GHZ state is used to detect eavesdroppers, and quantum dense coding is used to encode the message. In the security analysis, the method of entropy theory is introduced, and two detection strategies are compared quantitatively by using the constraint between the information that the eavesdroppers can obtain and the interference that has been introduced. If the eavesdropper wants to obtain all the information, the detection rate of the quantum secure direct communication using an Einstein-Podolsky-Rosen (EPR) pair block will be 50% and the detection rate of the presented protocol will be 87%. At last, the security of the proposed protocol is discussed. The analysis results indicate that the protocol proposed is more secure than the others

Flows of a Brinkman fluid due to a plane boundary moving in its plane are studied using Laplace transform. The solutions that have been obtained for the velocity are presented in simple forms in terms of the complementary error function erfc(.). They satisfy all imposed initial and boundary conditions and can easily be reduced to the similar solutions for Newtonian fluids

By the approximate symmetry perturbation method, the perturbed coupled nonlinear Schr¨odinger equation (PCNLSE) is investigated. As a result, the approximate symmetries and infinite series symmetry reduction solutions are obtained. Specially, we take the symmetry reduction for soliton solutions as an example, where the effects of perturbations on soliton solutions are briefly discussed

In this study, the homotopy perturbation transform method (HPTM) is performed to give approximate and analytical solutions of nonlinear homogenous and non-homogenous time-fractional gas dynamics equations. Gas dynamics equations are based on the physical laws of conservation, namely, the laws of conservation of mass, conservation of momentum, conservation of energy etc. The HPTM is a combined form of the Laplace transform, the homotopy perturbation method, and He’s polynomials. The nonlinear terms can be easily handled by the use of He’s polynomials. The numerical solutions obtained by the proposed method indicate that the approach is easy to implement and accurate. Some numerical illustrations are given. These results reveal that the proposed method is very effective and simple to perform

We designed a coupled resonator structure and studied its transmission properties through the tightbinding approach and the transfer matrix method. Based on the coupling of resonant modes and the electro-optic effect, some comb-channels with two orthogonal polarizations can be obtained. The total number of channels is two times the number of resonators. The orthogonal polarization channels cannot only be arranged alternately, but also be separated totally, just through adjusting the intensity of the external electric field. The split wavelength interval of two orthogonal polarizations is linear with the intensity of the external electric field

Lower and upper bounds for the Laplacian energy-like (LEL) molecular structure descriptor are obtained, better than those previously known. These bonds are in terms of number of vertices and edges of the underlying molecular graph and of graph complexity (number of spanning trees)

The spin Hamiltonian parameters (the anisotropic g factors g II , g ⟂ and hyperfine structure constants A II , A ⟂ ) for the Cu 2+ sites in sodium phosphate glasses Na 2 O-9P 2 O 5 and heavy metal fluoride glasses 60ZrF 4 -5LaF 3 -20BaF 2 -15NaF are theoretically investigated by using the high (fourth-) order perturbation formulas of these parameters for a 3d 9 ion in tetragonally elongated octahedra. In these formulas, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters Ds and Dt, are taken into account by considering the relative axial elongation of the ligand octahedron around the Cu 2+ due to the Jahn-Teller effect. According to the calculations, the ligand octahedra around Cu 2+ are suggested to suffer about 12% and 18% relative elongation along the C 4 -axis for the studied Na 2 O-9P 2 O 5 and 60ZrF 4 -5LaF 3 -20BaF 2 -15NaF glasses, respectively. The local structures characterized by the above axial elongations are discussed

The effects of surface roughness and surface force on thin film elastohydrodynamic lubrication (TFEHL) circular contact problems are analyzed and discussed under constant load condition. The multi-level multi-integration (MLMI) algorithm and the Gauss-Seidel iterative method are used to simultaneously solve the average Reynolds type equation, surface force equations, the load balance equation, the rheology equations, and the elastic deformation equation. The simulation results reveal that the difference between the TFEHL model and the traditional EHL model increase with decreasing film thickness. The effects of surface forces become significant as the film thickness becomes thinner. The surface forces have obvious effects in the Hertzian contact region. The oscillation phenomena in pressure and film thickness come mainly from the action of solvation forces

This work presents a new approach for three-dimensional (3D) coastal deformation simulation using differential synthetic aperture interferometry (DInSAR). In doing so, conventional InSAR procedures are implemented to three repeat passes of RADARSAT-1 SAR fine mode data (F1). Further, the DInSAR method is implemented with the phase unwrapping technique. Consequently, DInSAR is used to eliminate the phase decorrelation impact from the interferograms. The study shows the accurate performance of DInSAR with a root mean square error of 0:02 ±0:21 m and 90% confidence intervals. In conclusion, the DInSAR technique produces an accurate 3D coastal geomorphology reconstruction

This numerical study investigates the steady state natural convection of light and heavy water entering a vessel from the left and leaving on the right. The cavity consists of a matrix of cylindrical heated rods as in light and heavy water reactors. The aim of the study is to describe the effects of water inlet velocity on the flow and thermal fields in presence of such heated obstacle. The investigations are conducted for different values of rods temperatures. From the numerical results, it is evident that the flow pattern and temperature fields are significantly dependent on the water inlet velocity and rods temperature