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Rangpur, Bangladesh

Begum Rokeya University , formerly Rangpur University, is a government financed public university in Bangladesh. It is the second public university in Rangpur Division. Wikipedia.

Tasnim I.,Begum Rokeya University | Masud M.M.,Bangladesh University of Engineering and Technology | Mamun A.A.,Jahangirnagar University
Journal of the Korean Physical Society | Year: 2014

The fundamental properties of cylindrical and spherical dust-acoustic (DA) waves in dusty plasmas with consisting of negatively charged mobile dust, two populations of nonthermal ions with distinct temperatures, and Boltzmann-distributed electrons, are rigorously investigated both theoretically and analytically. The modified Gardner (mG) equation is derived by using the reductive perturbation method. The basic features of nonplanar DA modified Gardner solitons (mGSs) are analyzed by using numerical solutions of the mG equation. The nature and the basic characteristics of the mGSs are found to be significantly modified by the existence of two-temperature nonthermal ions. The implications of our investigations in understanding the nonlinear electrostatic perturbations observed in some astrophysical and space plasmas, where distinct-temperature nonthermal ions can significantly modify the wave dynamics, are briefly discussed in this current analysis. © 2014 The Korean Physical Society. Source

Tasnim I.,Begum Rokeya University | Masud M.M.,Bangladesh University of Engineering and Technology | Mamun A.A.,Jahangirnagar University
Plasma Physics Reports | Year: 2014

The effects of nonextensivity and nonthermality of ions of two distinct temperatures on dustacoustic Gardner solitons (DAGSs) in an unmagnetized dusty plasma system are investigated theoretically. The constituents of the dusty plasma under consideration are negatively charged mobile dust fluid, Boltzmann-distributed electrons, and ions of two distinct temperatures following nonextensive (q) and nonthermal distributions, respectively. The Korteweg-de Vries (KdV), modified KdV, and Gardner equations are derived by using the reductive perturbation technique, and thereby their characteristic features are compared. It is observed that both the nonextensive and nonthermal ions significantly modify the basic properties and polarities of dust-acoustic solitary waves. The present investigation may be of relevance to space and laboratory dusty plasma systems. © 2014, Pleiades Publishing, Ltd. Source

Abdur Razzak M.,Rajshahi University of Engineering and Technology | Mashiar Rahman M.,Begum Rokeya University
Results in Physics | Year: 2015

In this paper, a new novel energy balance method based on the harmonic balance method is proposed to obtain higher-order approximations of strongly nonlinear problems arising in engineering. Especially, second-order approximation is considered in this paper. Results found in this paper are compared with the exact result and other existing results. The results show that the proposed method gives better result for both small and large amplitudes of oscillation than other existing results. The method is illustrated by examples. It has been shown that the proposed method is very effective, convenient and quite accurate to nonlinear engineering problems. © 2015 The Authors. Source

Ashrafi K.S.,Begum Rokeya University | Mamun A.A.,Jahangirnagar University | Shukla P.K.,Ruhr University Bochum
Journal of Plasma Physics | Year: 2014

Polarization force (acting on a dust grain) and its modification by polarity of dust, non-isothermal (viz. non-thermal and trapped) ions, adiabaticity of electrons and ions, etc. have been investigated theoretically. It has been found that the polarization force is significantly modified by these effects, i.e. the magnitude of the polarization force is significantly decreased by the presence of non-thermal ions and by the adiabaticity of electrons and ions. On the other hand, it is significantly increased by the presence of trapped ions. It has been also shown that the magnitude of the polarization force is increased (decreased) by electric potential in the case of positively (negatively) charged dust. The relevance of our investigation to some space and astrophysical plasma situations is discussed. Copyright © 2013 Cambridge University Press. Source

Kamruzzaman M.,Begum Rokeya University | Dutta R.,City University of Bangladesh | Podder J.,Bangladesh University of Engineering and Technology
Semiconductors | Year: 2012

Cd 1 - xPb xS thin films were prepared by spray pyrolysis technique onto glass substrate at 300°C temperatures. The prepared films were characterized elemental, structural and optical properties by energy dispersive X-ray, scanning electron microscopy, X-ray diffraction and UV-VIS spectrophotometer. Energy dispersive X-ray confirmed the presence of Cd, S and Pb in the films. SEM images show that the deposition covered the substrate well uniformly and incorporation of Pb. Crystal structure was found hexagonal and the estimated grain size was lies in between 9 to 49 nm. The optical band gap was decreased from 2. 43 to 2. 07 eV. © 2012 Pleiades Publishing, Ltd. Source

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