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41.
Spatiotemporal Evolution of Intense Short Gaussian Laser Pulses in Weakly Relativistic Magnetized Plasma 下载免费PDF全文
The weakly relativistic regime of propagation of a short and intense laser pulse in the magnetized plasma is investigated. By considering relativistic nonlinearity and using non‐linear Schrödinger equation with paraxial approximation, two second‐order coupled differential equations are obtained for the longitudinal pulse width parameter (in time) and for the transverse pulse width parameter (in space). The simultaneous evolution of spot size and length of a relativistic Gaussian laser pulse in a magnetized plasma can be calculated by the numerical solution of the equations. The effect of magnetic field is investigated. It is observed that in the presence of magnetic field both the self‐compression and the self‐focusing can be enhanced. Furthermore, the interplay between the longitudinal self‐compression and the transverse self‐focusing in a magnetized plasma is investigated. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
42.
Ahmad Pouya Minh-Ngoc Vu Siavash Ghabezloo Zaky Bendjeddou 《International Journal of Solids and Structures》2013,50(20-21):3297-3307
This study focuses on a theoretical estimation of the effective permeability of unsaturated cracked porous media. The closed-form flow solution around and in a superconductive crack, embedded in an infinite porous matrix under a far-field condition, is recalled first. Then the solution of flow around a completely unsaturated (empty) crack that is considered as an obstruction against the flow is determined. The flow solution for partially saturated crack in special configurations is obtained by superposition of the two basic solutions for superconductive and empty cracks. The contribution of an unsaturated crack, with a given saturation degree, to the effective permeability is estimated by using dilute upscaling scheme. Numerical results obtained by Finite Elements Method, are in good agreement with the theoretical results for weak crack densities but show the additional effect of cracks interaction for higher densities. 相似文献
43.
Heydari Zahra Abdy Hamed Ghaziani Mohammad Pouya Kolahdouz Mohammadreza Asl-Soleimani Ebrahim Masnadi-Shirazi Mostafa 《Journal of Solid State Electrochemistry》2021,25(2):583-590
Journal of Solid State Electrochemistry - Organometallic halide perovskites have been arisen as a class of multi-purpose materials with exciting applications in optoelectronic devices such as solar... 相似文献
44.
Pouya Dastmalchi Nosrat Granpayeh Majid Rasouli Disfani 《Optical and Quantum Electronics》2010,42(4):231-239
In this paper we have investigated the performance of a nano-optical power splitter based on gap plasmon waveguides. The structure
consists of the rectangular gap plasmon waveguides in metal films. It is clear that the wave number and correspondingly light
confinement and the loss in the waveguides are the most effective parameters in power splitting, but as we know coupling length
is another important factor which should be considered. Some dependencies of the coupling length and the maximum transfer
power on the structure parameters are studied. It has been shown that approximately 43% transfer power for each arm of the
splitter is achievable. Simulation results have been obtained by the compact finite-difference time-domain method. The considered
structures, because of their small coupling length and dimensions are appropriate for implementation in photonic integrated
circuits. 相似文献
45.
The equations governing plane steady-state flow in heterogeneous porous media containing curved-line intersecting cracks (Pouya and Ghabezloo in Transp Porous Media 84:511?C532, 2010) and the potential solution obtained for these equations are considered here. The theoretical results are first completed for the mass balance at crack intersections points. Then, a numerical procedure based on a singular integral equations method is described concretely to derive this solution for cracked materials. Closed-form expressions of elementary integrals for special choice of collocation points lead to a very quick and easy numerical method. It is shown that this method can be applied efficiently to the study of the steady-state flow in cracked materials with anisotropic matrix permeability and a dense distribution of curved-line intersecting cracks. Some applications of this method to the permeability of cracked materials are given. 相似文献
46.
Guido Mann Jens Vogel Rüdiger Preuß Pouya Vaziri Mohammadali Zoheidi Markus Eberstein Jörg Krüger 《Applied Physics A: Materials Science & Processing》2008,92(4):853-857
High-power optical multimode fibers are essential components for materials processing and surgery and can limit the performance
of expensive systems due to breakdown at the end faces. The aim of this paper is the determination of laser-induced damage
thresholds (LIDT) of fibers (FiberTech) and preforms (Heraeus Suprasil F300). Preforms served as models. They were heated
up to maximum temperatures of 1100, 1300 and 1500°C and cooled down to room temperature at rates of 10 K min−1 (oven) and ∼105 K min−1 (quenched in air) to freeze in various structural states simulating different conditions similar to a drawing process during
the production of fibers. Single- and multi-pulse LIDT measurements were done in accordance with the relevant ISO standards.
Nd:YAG laser pulses with durations of 15 ns (1064 nm wavelength) and 8.5 ns (532 nm) at a repetition rate of 10 Hz were used.
For the preforms, LIDT values (1-on-1) ranged from 220 to 350 J/cm2 (1064 nm) and from 80 to 110 J/cm2 (532 nm), respectively. A multi-pulse impact changed the thresholds to lower values. The LIDT (1064 nm wavelength) of the
preforms can be regarded as a lower limit for those of the fibers. 相似文献
47.
Shahram Pouya Manoochehr M. Koochesfahani Andrew B. Greytak Moungi G. Bawendi Daniel G. Nocera 《Experiments in fluids》2008,44(6):1035-1038
Near-surface velocity measurements are carried out with quantum dot (QD) nanoparticles using evanescent wave illumination.
Relying on the small size of QDs, their correspondingly small hydrodynamic radius and high Brownian diffusion coefficient,
we consider the situation where the tracer diffusion length over the inter-frame time Δt is large compared to the size of the interrogation region next to the wall. While keeping all other experimental parameters
fixed, we systematically increase Δt by as much as a factor of 25, resulting in an increase of the QD diffusion length by a factor of 5. Data indicate a significant
overestimation of the “apparent” mean velocity measured experimentally. These results provide a direct confirmation of the
phenomenon of diffusion-induced bias described by the simulations of Sadr et al. (2007). 相似文献
48.
Pouya Maraghechi 《Surface science》2007,601(1):L1
The spontaneous dissociation of trichloroethylene molecules on the Si(1 1 1)7 × 7 surface was investigated using STM. Chlorine atoms were identified by using voltage dependent imaging and by observing voltage dependent tip-induced diffusion. At low coverage, we identify one chlorine that dissociates and binds to an adatom, leaving a nearby chlorovinyl group as the other product bound to the surface. Chlorine atoms show strong site selectivity for corner adatoms and some preference for the faulted half of the unit cell. This result differs significantly from previous studies of chlorine on this surface and a site-selective mobile precursor model is used to explain this discrepancy. The observed site-selectivity is consistent with the high electronegativity value for chlorine. 相似文献
49.
Ali Ebrahimi Sayyed Mostafa Habibi Khorassani Shiva Rezazadeh Abolfazl Azizi Pouya Karimi 《Molecular physics》2014,112(1):41-48
The mutual influence of cation–π and anion–π interactions in the π–Mz+–π–X?–π system (Mz+ = Li+, Na+, K+, Be2+, Mg2+, Ca2+ and X? = F?, Cl?) has been studied by quantum mechanical calculations. Both geometric parameters and energy data reveal that cation–π and anion–π interactions enhance each other in the π–Mz+–π–X?–π system. Individual binding energies (Eion···π) have been estimated in the quintuplet system using a simple new method from electron charge densities calculated at the bond critical points (BCPs) of the ion···π interaction by the atoms in molecules (AIM) method at the M062X/6-31+G(d) level of theory. With respect to the obtained individual binding energies, the strength of an ion···π interaction depends on the cooperative effects of other components. 相似文献
50.
Ali Ebrahimi Pouya Karimi Farideh Badichi Akher Roya Behazin Najmeh Mostafavi 《Molecular physics》2014,112(7):1047-1056
Stability of the π–π stacking interactions in the ben∥substituted-ben and ben∥substituted-COT complexes was studied using the computational quantum chemistry methods (where ben and COT are benzene and cyclooctatetraene, ∥ denotes π–π stacking interaction, substituted-ben and substituted-COT are benzene and cyclooctatetraene which substituted with four ethynyl-X groups, respectively, and X = OH, CH3, H, F, CF3, CN and NO2). In these complexes electron-withdrawing substituents lead to larger binding energies and electron-donating ones lead to weaker interactions compared to X = H. There are meaningful correlations between the Hammett constants and binding energies. The atoms in molecules (AIM) analysis shows that formation of these complexes is accompanied by increase in the electron charge densities at the ring critical points of the substituted-ben and substituted-COT rings which leads to increase/decrease of the π–π stacking interactions in the ben∥substituted-ben/ben∥substituted-COT complexes. The charge transfer occurs from benzene to substituted-ben in the ben∥substituted-ben complexes and from substituted-COT to benzene (with the exception of X = CN) in the ben∥substituted-COT ones. Nuclear magnetic resonance calculations demonstrate that interactions of the more aromatic substituted-ben/less anti-aromatic substituted-COT rings with benzene in the ben∥substituted-ben/ben∥substituted-COT complexes can be helpful to enhance strength of the π–π stacking interactions. Thus, regardless of ring size, the π–π stacking interaction is an aromatic–aromatic interaction and π electron cloud properties of interacting rings affect on the strength of this interaction. 相似文献