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161.
Mohd Hanapiah M. Yusoff H. Abu Hassan M.R. Hashim M.K. Abd-Rahman 《Optics Communications》2009,282(20):4063-4071
In this paper the analysis of multiple reflections in photonic crystal (PhC) multimode interference (MMI) couplers using eigen-mode expansion method is presented. The analysis is conducted on a hybrid PhC structure which consisted of 1-D PhC multimode waveguide sandwiched between 2-D PhC input/output waveguides. In PhC multimode waveguide, where the mechanism of wave confinement is not due to total internal reflection but due to photonic bandgap properties, the reflectivity at 2-D PhC facet wall would be very large for all the guided modes in the waveguide when ever the image formed due to MMI effect does not coincides with the output access waveguide. 相似文献
162.
Kavita Kumari Ankush Vij K. H. Chae Mohd. Hashim Rezq Naji Aljawfi P. A. Alvi 《辐射效应与固体损伤》2017,172(11-12):985-994
Ni-doped CeO2 nanoparticles were prepared by using the co-precipitation method. The prepared nanoparticles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The XRD results infer that Ni-doped CeO2 nanoparticles have single phase nature similar to that of pure CeO2 nanoparticles. We have calculated lattice parameters using Powder-X software, particle size using Scherer’s formula and strain using the Williamson-Hall method for all the synthesized samples. We have observed a systematic decrease in the lattice parameters, particle size and strain with an increase in Ni doping in CeO2. The FE-SEM micrographs also confirm that Ni-doped CeO2 have nanocrystalline behavior and particles are spherical shaped. From the Raman spectra, it is observed that the intensity of classical CeO2 vibration modes first increases then decreases with Ni doping. The NEXAFS spectra measured at Ce M4,5 and Ni L3,2 edges clearly indicate that Ce ions are in the +4 valence state and Ni ions are in the +2 valence state. 相似文献
163.
Sharul Ashikin Kamaruddin Kah-Yoong Chan Ho-Kwang Yow Mohd Zainizan Sahdan Hashim Saim Dietmar Knipp 《Applied Physics A: Materials Science & Processing》2011,104(1):263-268
Zinc oxide (ZnO) thin films and micro- and nanostructures are very promising candidates for novel applications in emerging
thin-film transistors, solar cells, sensors and optoelectronic devices. In this paper, a low-cost sol–gel spin coating technique
was used to fabricate ZnO films on glass substrates. The sol–gel fabrication process of the ZnO films is described. The influence
of precursor concentration on the material properties of the ZnO films was investigated. Atomic force microscopy and X-ray
diffractometry were employed to examine the structural properties of the ZnO films. The optical properties of the ZnO films
were characterized with ultraviolet–visible spectroscopy. The experimental results reveal that the precursor concentration
in the sol–gel spin coating process exerts a strong influence on the properties of the ZnO films. The effects of the precursor
concentration are discussed. 相似文献
164.
We extend the operational matrices technique to design a spectral solution of nonlinear fractional differential equations (FDEs). The derivative is considered in the Caputo sense. The coupled system of two FDEs is considered, subjected to more generalized integral type conditions. The basis of our approach is the most simple orthogonal polynomials. Several new matrices are derived that have strong applications in the development of computational scheme. The scheme presented in this article is able to convert nonlinear coupled system of FDEs to an equivalent S-lvester type algebraic equation. The solution of the algebraic structure is constructed by converting the system into a complex Schur form. After conversion, the solution of the resultant triangular system is obtained and transformed back to construct the solution of algebraic structure. The solution of the matrix equation is used to construct the solution of the related nonlinear system of FDEs. The convergence of the proposed method is investigated analytically and verified experimentally through a wide variety of test problems. 相似文献
165.
Khaled M. Chahrour Naser M. Ahmed M. R. Hashim Nezar G. Elfadill M. A. Qaeed 《Applied Physics A: Materials Science & Processing》2014,116(3):1389-1393
In this work, simple fabrication of hexagonally highly ordered porous anodic aluminum oxide (AAO) of Al thin film (1 μm) on Si substrate is described using two-step anodization method for electrochemical synthesis of nanostructures. In this method, the templates were prepared under the controllable conditions of the parameters, which give rise to the possibility of highly ordered nanopore arrays with a well aspect ratio. Pore widening was then fulfilled in 5 wt% phosphoric acid solution at 25 °C. The pore diameter and spacing are proportional to the applied voltage, which is due to the mechanical stress associated with the volume expansion of the aluminum during the anodization according to the mechanical stress model. Pore-widening solution adjusted the pore diameter and thinned the AAO barrier layer at room temperature under the control of etching time. As an application, Cu nanorods arrays embedded in anodic alumina (AAO) template were fabricated by dc electrodeposition. The characterization of the AAO templates and the Cu nanorods produced was made by X-ray diffraction, field emission scanning microscope, energy dispersive X-ray spectroscopy and atomic force microscope (AFM). The images of AFM show that porous AAO template under constant voltage is 40 V which presents the optimum ordering. 相似文献
166.
Alfonso Martinez-Felipe Thamil Selvi Velayutham Marina Yusoff Emma Farquharson Rauzah Hashim 《Liquid crystals》2020,47(8):1180-1194
ABSTRACT Glycolipids prepared from palm kernel oil, PKO, in tropical regions represent an excellent opportunity to develop new surfactant formulations for cosmeceutical and pharmaceutical applications while contributing to sustainable economies. Here we report the synthesis of a new mannoside obtained from palm kernel oil, aManPKO, and we characterise its thermotropic properties by using DSC, POM, SAXS, WAXS, FT-IR and broadband dielectric spectroscopy. aManPKO exhibits a monotropic smectic phase with a partially interdigitated bilayer structure, similar to its major unsaturated component, the oleyl mannoside with a C18:1 monounsaturated alkyl chain. The smectic phase of aManPKO vitrifies below room temperature, which is associated to the C18:1 component, but also to the activation of short-range motions, ~4 Å, by cleavage of strong hydrogen bonding between the polar heads of the mannosides. The stability of the liquid crystal phase, on the other hand, is linked to the presence of weak hydrogen bonding, whose breakage leads to the activation of long rate motions in the range of the layer distances, ~39 Å. 相似文献
167.
In this article we study the combined effect of internal heating and time-periodic gravity modulation on thermal instability in a closely packed anisotropic porous medium, heated from below and cooled from above. The time-periodic gravity modulation, considered in this problem can be realized by vertically oscillating the porous medium. A weak non-linear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number has been obtained in terms of the amplitude of convection which is governed by the non-autonomous Ginzburg?CLandau equation derived for the stationary mode of convection. The effects of various parameters such as; internal Rayleigh number, amplitude and frequency of gravity modulation, thermo-mechanical anisotropies, and Vadász number on heat transport has been analyzed. It is found that the response of the convective system to the internal Rayleigh number is destabilizing. Further it is found that the heat transport can also be controlled by suitably adjusting the external parameters of the system. 相似文献
168.
M.S.H. Chowdhury I. Hashim S. Mawa 《Communications in Nonlinear Science & Numerical Simulation》2009,14(4):1008-1012
In this paper, an analytical expression for the solution of the prey–predator problem by an adaptation of the classical Adomian decomposition method (ADM). The ADM is treated as an algorithm for approximating the solution of the problem in a sequence of time intervals, i.e. the classical ADM is converted into a hybrid numeric–analytic method called the multistage ADM (MADM). Numerical comparisons with the classical ADM, and the classical fourth-order Rungge–Kutta (RK4) methods are presented. 相似文献
169.
170.
Approximate analytical solutions for free convection boundary layers on a heated vertical plate with lateral mass flux embedded
in a saturated porous medium are presented using the modified Adomian decomposition method and Padé technique. Several values
of the wall temperature exponent for illustrating the effects of suction/injection parameter on the flow and heat transfer
are considered. This study also includes the influence of the exponent on an impermeable surface. The results obtained are
comparable to the exact analytical solutions and elucidate reliability and efficiency of the technique. 相似文献