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121.
Mohamed Lazoul Azzedine Boudrioua Lotfy Mokhtar Simohamed Alexis Fischer Lung Han Peng 《Applied physics. B, Lasers and optics》2013,110(4):459-464
We report a detailed study of multiple wavelengths optical parametric generation in a single grating one-dimensional periodically poled lithium tantalate crystal. Simultaneous collinear and non-collinear generations are observed around the pump collinear direction. Similar spectra are found in continuous spatial positions symmetrical to the collinear direction, with decreasing signal and increasing idler wavelengths, associated with decreasing powers when the far-field angle increases. A phase matching scheme is proposed to describe these interactions. Numerical simulations emphasize the agreement of our phase matching scheme with the experimental results. Single-pass gain and high pump power density are very likely at the origin of the simultaneous collinear and non-collinear QPM interactions. 相似文献
122.
Mokhtar Kirane Salman A. Malik Mohammed A. Al‐Gwaiz 《Mathematical Methods in the Applied Sciences》2013,36(9):1056-1069
We consider the inverse source problem for a time fractional diffusion equation. The unknown source term is independent of the time variable, and the problem is considered in two dimensions. A biorthogonal system of functions consisting of two Riesz bases of the space L2[(0,1) × (0,1)], obtained from eigenfunctions and associated functions of the spectral problem and its adjoint problem, is used to represent the solution of the inverse problem. Using the properties of the biorthogonal system of functions, we show the existence and uniqueness of the solution of the inverse problem and its continuous dependence on the data. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
123.
Ehsan Mohammadpour Mokhtar Awang 《Applied Physics A: Materials Science & Processing》2012,106(3):581-588
An effective finite-element (FE) approach for modeling the structure and the deformation of single-walled carbon nanotubes
(SWCNTs) and multi-walled carbon nanotubes (MWCNTs) is presented. An individual tube was modeled using a frame-like structure
with beam elements. The effect of van der Waals forces, crucial in MWCNTs, was modeled by spring elements. The success of
this new carbon nanotube (CNT) modeling approach was verified by comparing the simulation results for single- and multi-walled
nanotubes and graphene with other experimental and computational results available in the literature. Simulations of final
deformed configurations were in excellent agreement with the atomistic models for various deformations. The proposed approach
successfully predicts the experimentally observed values for mechanical behavior of SWCNTs and MWCNTs. The results demonstrated
that the proposed FE technique could provide a valuable tool for studying the mechanical behavior of different types of nanotubes,
as well as their effectiveness as load-bearing entities in nanocomposite materials. 相似文献
124.
N.S. Shahabuddin N.A. Awang H. Ahmad H. Arof K. Dimyati Z. Yusoff S.W. Harun 《Optics & Laser Technology》2012,44(4):741-743
A Supercontinuum (SC) generation in photonic crystal fiber (PCF) is demonstrated using an amplified picosecond stretched-pulses from a passive mode-locked Bismuth-based Erbium-doped fiber laser (Bi-EDFL). The Bi-EDFL employs of a piece of a highly nonlinear 49 cm long Bismuth-based Erbium-doped fiber (Bi-EDF), an optical isolator and a polarization controller in a cavity to generate a mode-locked stretched-pulse via a nonlinear polarization rotation technique. It operates at 1560 nm with a repetition rate of 42 MHz and a pulse width of 131 fs. The SC lights, which extends from 1250 nm to 1910 nm as well as in the visible green wavelength region are obtained with a 100 m long PCF and the amplified pump power of 30 dBm. 相似文献
125.
Chen T Wang Q Chen R Zhang B Jewart C Chen KP Maklad M Swinehart PR 《Optics letters》2012,37(6):1064-1066
We present spatially resolved Rayleigh scattering measurements in different polarization-maintaining (PM) fibers for high-temperature pressure sensing. The pressure-induced birefringence in the fiber cores is interrogated using polarization-resolved frequency-swept interferometry. The pressure responses of a PM photonic crystal fiber and a twin-air-hole PM fiber are investigated for a pressure range of 0 to 13.8 MPa (0-2000 psi) at room temperature and at temperatures as high as 800 °C. The proposed sensing system provides, for the first time to our knowledge, a truly distributed pressure-sensing solution for high-temperature applications. 相似文献
126.
Awad A. Ibraheem M. A. Hassanain S. R. Mokhtar M. A. Zaki Zakaria M. M. Mahmoud M. El-Azab Farid 《Physics of Atomic Nuclei》2012,75(8):969-972
Microscopic folding calculations based upon the effective M3Y nucleon-nucleon interaction and the nuclearmatter densities of the interacting nuclei have been carried out to explain recently measured experimental data of the 6He+120Sn elastic scattering cross section at four different laboratory energies near the Coulomb barrier. The extracted reaction cross sections are also considered. 相似文献
127.
Jean-Marc Richard Xavier Artru Mokhtar Elchikh Jacques Soffer Oleg Teryaev 《中国物理 C》2009,33(12):1153-1158
We discuss model-independent constraints on spin observables in exclusive and inclusive reactions, with special attention to the case of photoproduction. 相似文献
128.
A simple and sensitive method for the analysis of sterols, tocopherols and triterpenic dialcohols from the unsaponifiable fraction from oil samples in a single analytical run using liquid chromatography coupled to mass spectrometry was developed. With this method, the compounds could be detected directly after dissolving the unsaponifiable fraction in acetonitrile without necessity of time-consuming sample pre-treatment or derivatization. Separation of the analytes was carried out at room temperature, by using a C18 column (5 μm i.d. 3.0 mm × 250 mm) with a linear gradient of acetonitrile/water (0.01% acetic acid) at a flow rate of 1.5 mL/min. The full scan mass spectra of the investigated compounds were measured by an ion trap mass spectrometer equipped with an APCI ion source. The optimized methodology was suitable for the identification of 23 compounds belonging to different families present in olive oil and other kinds of oils, as well as for the quantification of 15 analytes (vs. their commercial standards). 相似文献
129.
130.
In this paper we consider a nonlinear programming problem of the form to minimize f(x) subject to a x b, where f is a differentiable function on En and a and b are fixed vectors in En. We develop a variation of the feasible direction algorithm of Topkis and Veinott for solving the above problem and provide explicit expressions of the optimal directions for a family of direction-finding problems using different normalization constraints. We show that the algorithm converges to a Kuhn-Tucker point. The reported computational results indicate efficiency of the algorithm. It also indicates the strong effect of the form of the normalization constraint on convergence properties. 相似文献