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In a recent article [C. Li et al., Phys. Plasmas 21, 072114 (2014)], Li et al. studied the propagation of surface waves on a magnetized quantum plasma half-space in the Voigt configuration (in this case, the magnetic field is parallel to the surface but is perpendicular to the direction of propagation). Here, we present a fresh look at the problem and obtain a new form of dispersion relation of surface waves of the system. We find that our new dispersion relation does not agree with the result obtained by Li et al. © 2016 Author(s). Source


Naderi A.,Kermanshah University of Technology
Materials Science in Semiconductor Processing | Year: 2015

A new double gate graphene nanoribbon field effect transistor with dual material for gate namely DMG-GNRFET is proposed. DMG-GNRFET includes a gate which is divided to the left and right side materials with different work functions. The left side metal (the source side) has lower work function than the right side one. This difference creates a step in potential profile which decreases band to band tunneling. Due to this step, the proposed structure has lower subthreshold swing, higher saturation current, lower leakage current and consequently higher current ratio than conventional structure. These advantages make DMG-GNRFET more suitable for digital applications. Transport properties of the proposed structure are compared to conventional GNRFET. The devices have been simulated based on self-consistent solution of Poisson and Schrodinger equations within non-equilibrium Green's function formalism. The effects of third nearest neighbor, dangling bands, and edge roughness have been included in the procedure to obtain more reliable simulations. & 2014 Elsevier Ltd. All rights reserved. Source


Tipi A.D.,Kermanshah University of Technology
International Journal of Advanced Manufacturing Technology | Year: 2011

Two forces play the main role on the drop detachment in gas metal arc welding process: the electromagnetic and gravitational forces. Since in an automatic pipeline system, the welding angle varies from 0° to 180° in each pass, the total force will vary, so the drop detaching will not remain invariable during the welding time. In the previous works Doodman Tipi (Int J Adv Manu Technol 50:137-147, 2010 [1]), Doodman Tipi (Int J Adv Manu Technol 50:149-161, 2010 [2]), the angle variation effects on the metal transfer was studied on both transfer modes (free flight and short circuit). In this paper, the effect of the input parameters on the drop detaching is studied. Also, a welding current pattern is presented in order to neutralize the effect of the angle variation around the pipe. Furthermore, suitable patterns for other parameters (arc voltage, travel speed, and electrode speed) are introduced to keep constant the molten electrode volume, heat input, voltage to current relation, and energy density. This would guarantee stabilization of the other welding specifications. Finally, several experimental and simulation examples illustrate to achieve the regular detachment using the presented method, and results are compared with the un-neutralized case. © Springer-Verlag London Limited 2010. Source


Moradi A.,Kermanshah University of Technology
Surface Science | Year: 2015

We develop a new method for calculating the electrostatic surface and bulk plasmon modes of a spherical metal nanoparticle, by taking into account the quantum nonlocal effects. To describe these phenomena, we develop analytical theory based on the quantum hydrodynamical model of plasmon excitation. We derive new dispersion relation for the system and investigate its differences with previous treatments based on the standard nonlocal model. © 2015 Elsevier B.V. Source


Bahiraei M.,Kermanshah University of Technology | Hangi M.,Iran University of Science and Technology
Journal of Magnetism and Magnetic Materials | Year: 2015

Magnetic nanofluids (MNFs) are suspensions which are comprised of a non-magnetic base fluid and magnetic nanoparticles. In this modern set of suspensions which can be called smart or functional fluids, fluid flow, particles movement and heat transfer process can be controlled by applying magnetic fields. Regarding unique characteristics of MNFs, studies in this field have witnessed a phenomenal growth. This paper reviews and summarizes recent investigations implemented on MNFs including those conducted on thermophysical properties, natural convection, forced convection, boiling as well as their practical applications. Moreover, this review identifies the challenges and opportunities for future research. © 2014 Elsevier B.V. Source

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