Damghan, Iran

Time filter

Source Type

Mehrad M.,Damghan University
Superlattices and Microstructures | Year: 2015

In this paper a new technique for controlling floating body effect and self-heating effects is proposed. The main idea in the proposed structure is using a L-shape SiGe region in the nano-scale SOI-MOSFET (LS-SOI). The L-shape SiGe region is located in the source region and is extended under channel. The difference band gap between silicon and silicon-germanium cause discontinuity in band diagram which helps to collect channel holes. Reducing the hole density in channel of the proposed LS-SOI in comparison to conventional SOI-MOSFET (C-SOI) results in suppressed floating body effect. Also, the SiGe region under the channel decreases the lattice temperature in the LS-SOI. Replacing the SiGe with higher thermal capability than buried oxide is useful to have a reliable structure. Moreover, effective mobility, off current and sub-threshold swing improves in the proposed structure. © 2015 Elsevier Ltd. All rights reserved.

Zareiee M.,Damghan University
Superlattices and Microstructures | Year: 2015

In this paper a novel feature of a nano-scale SOI-MOSFET is presented. The goal of the proposed Si3N4 Layer SOI-MOSFET (SL-SOI) is inserting a Si3N4 layer in the channel region. This layer in the channel region which has different band gap than silicon causes uniform electric field. So, hot carrier effect and gate current are controlled sufficiently. Moreover, Si3N4 layer in the channel is extended in the buried oxide to reduce the lattice temperature, and sub-threshold slope. The proposed structure is simulated with two-dimensional ATLAS simulator and compared with conventional SOI-MOSFET. The results show that the new device has a high performance which expands nano-scale MOSFET applications in high temperature. © 2015 Elsevier Ltd. All rights reserved.

Grivani G.,Damghan University | Akherati A.,Damghan University
Inorganic Chemistry Communications | Year: 2013

Polymer-supported bis (2- hydroxylanyl) acetylacetone Schiff base ligand was prepared by reaction of bis (2- hydroxylanyl) acetylacetone with chloromethylated polystyrene in DMF. In the subsequent reaction of this polymer-supported Schiff base ligand with MoO2(acac)2 the polymer-supported bis (2- hydroxylanyl) acetylacetonato MoO2 Schiff base complex was prepared. This polymer-supported molybdenum Schiff base catalyst was highly active and selective in epoxidation of various alkenes in the presence of tert-buthyl hydroperoxide (TBHP) in CCl4. It can be recovered and reused for 8 times without any loss in its activity. © 2012 Elsevier B.V.

Abbasi Molai A.,Damghan University
Information Sciences | Year: 2013

In this paper, the LU-factorization is extended to the fuzzy square matrix with respect to the max-product composition operator called L°U- factorization. Equivalently, we will find two fuzzy (lower and upper) triangular matrices L and U for a fuzzy square matrix A such that A = L°U, where "°" is the max-product composition. An algorithm is presented to find the matrices L and U. Furthermore, some necessary and sufficient conditions are proposed for the existence and uniqueness of the L°U-factorization for a given fuzzy square matrix A. An algorithm is also proposed to find the solution set of a square system of Fuzzy Relation Equations (FRE) using the L°U-factorization. The algorithm finds the solution set without finding its minimal solutions and maximum solution. It is shown that the two algorithms have a polynomial-time complexity as O(n3). Since the determination of the minimal solutions is an NP-hard problem, the algorithm can be very important from the practical point of view. © 2011 Elsevier Inc. All rights reserved.

Pourhassan B.,Damghan University
Physics of the Dark Universe | Year: 2016

In this paper, we investigate cosmological models of the extended Chaplygin gas in a universe governed by Horava-Lifshitz gravity. The equation of state for an extended Chaplygin gas is a (n+2)-variable equation determined by An, α, and B. In this work, we are interested to the case of second order (n=2) equation of state which recovers quadratic barotropic equation of state. In that case there are four free parameters. We solve conservation equation approximately and obtain energy density in terms of scale factor with mentioned free parameters. Under some assumptions we relate free parameters to each other to have only one free independent parameter (A2). It help us to obtain explicit expression for energy density in terms of scale factor. The allowed values of the second order extended Chaplygin gas parameter is fixed using the recent astrophysical and cosmological observational data. Thermodynamics of the model investigated based on the first and second law of thermodynamics. © 2016.

Eskandari K.,Damghan University
Journal of Molecular Modeling | Year: 2012

The nature of beryllium bonds formed between BeX2 (X is H, F and Cl) and some Lewis bases have been investigated. The distribution of the Laplacian of electron density shows that there is a region of charge depletion around the Be atom, which, according to Laplacian complementary principal, can interact with a region of charge concentration of an atom in the base and form a beryllium bond. The molecular graphs of the investigated complexes indicate that beryllium in BeH2 and BeF2 can form "beryllium bonds" with O, N and P atoms but not with halogens. In addition, eight criteria based on QTAIM properties, including the values of electron density and its Laplacian at the BCP, penetration of beryllium and acceptor atom, charge, energy, volume and first atomic moment of beryllium atom, have been considered and compared with the corresponding ones in conventional hydrogen bonds. These bonds share many common features with very strong hydrogen bonds, however, some differences have also been observed. © Springer-Verlag 2012.

Vali R.,Damghan University
Computational Materials Science | Year: 2011

The electronic band structure, dielectric function, and phonon spectra of SrMoO4 have been studied using density functional theory within the local density approximation. The origin of the peaks in the imaginary part of the dielectric function was analyzed based on the electronic structure. The calculated phonon spectra are in good agreement with available Raman experimental data and provide benchmark theoretical results for the interpretation of future infrared phonon measurements. © 2011 Elsevier B.V. All rights reserved.

Abbasi Molai A.,Damghan University
Computers and Industrial Engineering | Year: 2012

The quadratic programming has been widely applied to solve real world problems. The quadratic functions are often applied in the inventory management, portfolio selection, engineering design, molecular study, and economics, etc. Fuzzy relation inequalities (FRI) are important elements of fuzzy mathematics, and they have recently been widely applied in the fuzzy comprehensive evaluation and cybernetics. In view of the importance of quadratic functions and FRI, we present a fuzzy relation quadratic programming model with a quadratic objective function subject to the max-product fuzzy relation inequality constraints. Some sufficient conditions are presented to determine its optimal solution in terms of the maximum solution or the minimal solutions of its feasible domain. Also, some simplification operations have been given to accelerate the resolution of the problem by removing the components having no effect on the solution process. The simplified problem can be converted into a traditional quadratic programming problem. An algorithm is also proposed to solve it. Finally, some numerical examples are given to illustrate the steps of the algorithm.

Faghei K.,Damghan University
Monthly Notices of the Royal Astronomical Society | Year: 2012

The purpose of this paper is to explore the dynamical behaviour of hot accretion flows with thermal conduction. The importance of thermal conduction in hot accretion flows is confirmed by observations of the hot gas that surrounds SgrA* and a few other nearby galactic nuclei. In this research, the effect of thermal conduction is studied through a saturated form, as is appropriate for weakly collisional systems. The angular momentum transport is assumed to be a result of viscous turbulence and the α-prescription is used for the kinematic coefficient of viscosity. The equations of accretion flow are solved in a simplified one-dimensional model that neglects the latitudinal dependence of the flow. To solve the integrated equations that govern the dynamical behaviour of the accretion flow, we have used an unsteady self-similar solution. The solution provides some insights into the dynamics of quasi-spherical accretion flow and avoids the limits of the steady self-similar solution. In comparison with accretion flows without thermal conduction, the disc generally becomes cooler and denser. These properties are qualitatively consistent with simulations performed in hot accretion flows. Moreover, the angular velocity increases with the magnitude of conduction, while the radial infall velocity decreases. The mass accretion rate on to the central object is reduced in the presence of thermal conduction. We found that viscosity and thermal conduction have opposite effects on the physical variables. Furthermore, the flow represents a transonic point that displaces inward with the magnitude of conduction or viscosity. © 2011 The Author Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Ghal-Eh N.,Damghan University
Radiation Physics and Chemistry | Year: 2011

A Monte Carlo simulation of the light transit time in scintillation detectors is described, with the wavelength dependencies of different interaction processes being taken into account. The simulation results presented give an estimate of the contribution of light transport to the timing resolution of scintillation detectors. © 2010 Elsevier Ltd.

Loading Damghan University collaborators
Loading Damghan University collaborators