Rahman M.M.,Chittagong University of Engineering and Technology
International Journal of Hydrogen Energy | Year: 2015
Aqueous-phase reforming of glycerol was investigated over a series of Ni and Cu-Ni bimetallic catalysts supported on multiwalled carbon nanotubes (MWNT). The reaction was carried out in a continuous flow fixed bed reactor (240 °C, 40 atm) with a solution of 1 wt% glycerol in DI water at a flow rate of 0.05 mL/min. Amongst the catalysts tested, bimetallic 1Cu-12Ni/MWNT catalyst gave the higher H2 selectivity (86%) and glycerol conversion (84%) than the benchmark 12Ni/MWNT catalyst. Irrespective of Cu and Ni ratio, bimetallic Cu-Ni catalysts showed higher selectivity and glycerol conversion towards H2 production than the Ni catalyst. The presence of Cu in bimetallic catalysts resulted in suppression of undesirable methanation reaction. Catalysts characterized by XRD and XPS showed a significant peak shift of Ni in bimetallic Cu-Ni catalysts than the Ni catalyst, suggesting a strong interaction between Cu and Ni. Also H2-TPR analysis showed that introducing Cu increased Ni reducibility. The bimetallic interaction is thought to be responsible for the lowered methane yield and ultimately, higher hydrogen yield observed. © 2015 Hydrogen Energy Publications, LLC.
Hafez M.G.,Chittagong University of Engineering and Technology
Alexandria Engineering Journal | Year: 2016
In this article, the exp(-Φ(ξ))-expansion method is modified for (3+1)-dimensional space-time coordinate system and successfully implemented to construct the new exact traveling wave solutions of the (3+1)-dimensional coupled Klein-Gordon-Zakharov equation. The solutions of this equation are expressed in terms of hyperbolic, trigonometric, exponential and rational functions. The results illustrate its effectiveness for solving nonlinear coupled partial differential equations arises in mathematical physics and engineering. The annihilation phenomena of the wave propagation in the x-y plane are also investigated. Furthermore, the three-dimensional surface plots due to the obtained solutions are also given to make the dynamics of the equation visible. © 2016 Faculty of Engineering, Alexandria University.
Humayun Kabir S.M.,Chittagong University of Engineering and Technology |
Yeo T.-I.,University of Ulsan
Journal of Mechanical Science and Technology | Year: 2014
In this paper, an attempt is made to extend the total strain energy approach for predicting the fatigue life subjected to mean stress under uniaxial state. The effects of means stress on the fatigue failure of a ferritic stainless steel and high pressure tube steel are studied under strain-controlled low cycle fatigue condition. Based on the fatigue results from different strain ratios, modified total strain energy density approach is proposed to account for the mean stress effects. The proposed damage parameter provides convenient means of evaluating fatigue life with mean stress effects considering the fact that the definitions used for measuring strain energies are the same as in the fully-reversed cycling (R = -1). A good agreement is observed between experimental life and predicted life using proposed approach. Two other mean stress models (Smith-Watson-Topper model and Morrow model) are also used to evaluate the low cycle fatigue data. Based on a simple statistical estimator, the proposed approach is compared with these models and is found realistic. © 2014 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.
Bhuiya M.M.K.,Central Queensland University |
Bhuiya M.M.K.,Chittagong University of Engineering and Technology |
Chowdhury M.S.U.,University of New South Wales |
Saha M.,University of Adelaide |
Islam M.T.,University of Malaya
International Communications in Heat and Mass Transfer | Year: 2013
This work deals with the experimental investigation on Nusselt number, friction factor and thermal performance factor in a circular tube equipped with perforated twisted tape inserts with four different porosities of Rp = 1.6, 4.5, 8.9 and 14.7%. The experiments were conducted in a turbulent flow regime with Reynolds number ranging from 7200 to 49,800 using air as the working fluid under uniform wall heat flux boundary condition. The experimental results revealed that both heat transfer rate and friction factor of the tube fitted with perforated twisted tapes were significantly higher than those of the plain tube. Over the range investigated, Nusselt number, friction factor and thermal performance factor in the tube with perforated twisted tape inserts was found to be 110 -340, 110 -360 and 28-59% higher than those of the plain tube values, respectively. In addition, the empirical correlations of Nusselt number, friction factor and thermal performance factor were formulated from the experimental results of tape inserts. © 2013 Elsevier Ltd.
Dombkowski A.A.,Wayne State University |
Sultana K.Z.,Chittagong University of Engineering and Technology |
Craig D.B.,Wayne State University
FEBS Letters | Year: 2014
Improving the stability of proteins is an important goal in many biomedical and industrial applications. A logical approach is to emulate stabilizing molecular interactions found in nature. Disulfide bonds are covalent interactions that provide substantial stability to many proteins and conform to well-defined geometric conformations, thus making them appealing candidates in protein engineering efforts. Disulfide engineering is the directed design of novel disulfide bonds into target proteins. This important biotechnological tool has achieved considerable success in a wide range of applications, yet the rules that govern the stabilizing effects of disulfide bonds are not fully characterized. Contrary to expectations, many designed disulfide bonds have resulted in decreased stability of the modified protein. We review progress in disulfide engineering, with an emphasis on the issue of stability and computational methods that facilitate engineering efforts. © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.