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Chakraborty T.K.,Presidency University of Bangladesh
International Journal of Power Electronics and Drive Systems | Year: 2016

This paper concerns the experimental investigations of the three-phase line commutated SCR inverter fed synchronous motor. The fabricated system consists of a line-commuted inverter, a three-phase synchronous motor with the excitation winding connected in series to the inverter input, a terminal voltage sensor and a gate-pulse generating circuit. The firing pulses for SCRs of the inverter are generated by the microprocessor in proper sequence with the help of synchronizing signal derived from the terminal voltages of the synchronous machine. The steady state performance characteristics are obtained experimentally using the fabricated system. The experimental results show that a three-phase synchronous motor supplied by a line commutated inverter with the excitation winding connected in series to the dc link provide excellent characteristics of the conventional dc series motor. © 2016 Institute of Advanced Engineering and Science. All rights reserved. Source


Abdul Jalil M.,Presidency University of Bangladesh | Masum S.M.,University of Dhaka
Tetrahedron Letters | Year: 2012

A general and efficient method for the preparation of biologically important imidazolyl alcohols via ring-opening of epoxides with N-silylated imidazole catalyzed by LiBr under solvent-free conditions is reported. © 2012 Elsevier Ltd. All rights reserved. Source


Taufique K.M.R.,Presidency University of Bangladesh | Shahriar F.M.,Leading University
International Journal of e-Business Research | Year: 2013

Few but mentionable studies have been conducted in typifying the Online Social Media (OSM) users. Studies on innovations taking place within the OSM environment are also very much found. But gaps are present in linking OSM innovations and adoption of innovations by the OSM users. Precise and objective studies to put the OSM users in an adoption spectrum are close to nil, though such studies might carry great significance in this new but exploding field of business and marketing. This study focuses on proposing an 'Adoption Spectrum' for OSM innovations by the users by proliferating Rogers's 'Adoption of Innovation' with the 'Typology of OSM Users'. Absolutely conceptual and qualitative in nature, the study concentrates on assessing the speed and magnitude of adoption of OSM innovations by the users. The proposed spectrum is an alignment between Rogers's work and the OSM user typology. Mentionable limitation of this piece of work may be forwarding the empirical justifications for further study. However, the study may be used as input for managing innovations by the firms that venture through OSM. Copyright © 2013, IGI Global. Source


Bhuyan M.H.,Bangladesh University of Engineering and Technology | Bhuyan M.H.,Presidency University of Bangladesh | Khosru Q.D.M.,Bangladesh University of Engineering and Technology
World Academy of Science, Engineering and Technology | Year: 2011

Carriers scattering in the inversion channel of n- MOSFET dominates the drain current. This paper presents an effective electron mobility model for the pocket implanted nano scale n-MOSFET. The model is developed by using two linear pocket profiles at the source and drain edges. The channel is divided into three regions at source, drain and central part of the channel region. The total number of inversion layer charges is found for these three regions by numerical integration from source to drain ends and the number of depletion layer charges is found by using the effective doping concentration including pocket doping effects. These two charges are then used to find the effective normal electric field, which is used to find the effective mobility model incorporating the three scattering mechanisms, such as, Coulomb, phonon and surface roughness scatterings as well as the ballistic phenomena for the pocket implanted nano-scale n-MOSFET. The simulation results show that the derived mobility model produces the same results as found in the literatures. Source


Nazmul I.M.,Presidency University of Bangladesh | Matsumoto T.,Hokkaido University
International Journal of Solids and Structures | Year: 2012

A new mathematical procedure has been proposed for the determination of crack bridging stresses from perturbed crack opening displacements (COD) in fiber composites. The problem is an ill-posed inverse problem and the proposed procedure exploited concepts from functional analysis and the theory of inverse problems. The transformation from crack bridging stress into COD has been linearized, where the continuous crack bridging stresses functions of infinite dimensional vector spaces were approximated into finite dimensional subspaces. The coordinate representation of functions and the matrix of the transformation facilitated a numerical solution to the inverse problem. Self consistent direct and inverse problems were solved numerically in context to an example. Results establish that the proposed mathematical procedure produces fairly accurate results for engineering application. © 2011 Elsevier Ltd. All rights reserved. Source

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