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Razzak M.A.,Rajshahi University of Engineering and Technology
Alexandria Engineering Journal | Year: 2017

In this paper, a new noble modified iterative method is proposed to obtain the approximate solution of strongly nonlinear oscillator systems having a rational and an irrational forces. The approximate frequency and the corresponding periodic solution can easily be determined by the present proposed method. Two examples are considered to illustrate the effectiveness and convenience of this procedure. The results obtained in this paper show good agreement with the corresponding numerical solution (considered to be exact) for both small and large amplitudes of oscillation. Furthermore, the method provides better result than other existing results (those results obtained by several authors). The main advantage of the present method is its simplicity which contains up to third harmonic terms. These harmonic terms make the solution rapidly converge. The method is important and powerful for solving nonlinear oscillator systems arising in nonlinear science and engineering. © 2017 Faculty of Engineering, Alexandria University.

Mustafi N.N.,Rajshahi University of Engineering and Technology | Raine R.R.,University of Auckland | Verhelst S.,Ghent University
Fuel | Year: 2013

Among the different efforts towards the reduction in pollutant emissions from direct injection (DI) diesel engines, the use of gaseous fuels as a partial supplement for diesel fuel has been proposed by many researchers. An experimental investigation was performed to investigate the influence of dual-fuel combustion on the performance and exhaust emissions of a DI diesel engine fueled with natural gas (NG) and biogas (BG). The engine was operated at a constant speed of 1750 rpm and at two different loads: low (∼3 N m) and high (∼28 N m), which were about 10% and 85% respectively of the rated torque output of the engine at 1800 rpm. In this work, the combustion pressure and the rate of heat release were evaluated experimentally in order to analyze the combustion characteristics and their effects on exhaust emissions including particulate matter (PM) for single-fuel (diesel) and dual fuel combustion modes. In dual fuel mode, the peak cylinder pressure was found to be similar to diesel at 75% of the rated output of the engine. About 27-30% higher maximum net heat release rates were obtained for NG and biogas fueling respectively compared to diesel fueling. Longer ignition delays but shorter combustion durations were characterized for dual fueling operations. Specific NOx emissions for dual fueling was always lower than diesel fueling case. Significantly lower specific PM emissions but sharply increased unburned hydrocarbons (UHC) emissions were measured for biogas-diesel dual fuel operations as compared to diesel fueling. © 2013 Elsevier Ltd. All rights reserved.

Islam M.R.,Rajshahi University of Engineering and Technology | Parveen M.,Kitami Institute of Technology | Haniu H.,Kitami Institute of Technology
Bioresource Technology | Year: 2010

Agricultural waste in the form of sugarcane bagasse was pyrolyzed in a fixed-bed fire-tube heating reactor under different pyrolysis conditions to determine the role of final temperature, sweeping gas flow rate and feed size on the product yields. Final temperature range studied was between 375 and 575 °C and the highest liquid product yield was obtained at 475 °C. Liquid products obtained under the most suitable conditions were characterized by physical properties, elemental analysis, GCV, FT-IR, 1H NMR analysis and distillation. The empirical formula of the bio-oil with heating value of 23.5 MJ/kg was established as CH 1.68O 0.557N 0.012. Comparison with other approaches showed that the liquid product yield by this simpler reactor system was higher with better physico-chemical properties as fuel. These findings show that fixed-bed fire-tube heating pyrolysis is a good option for production of bio-oils from biomass solid wastes. © 2010 Elsevier Ltd. All rights reserved.

Islam S.M.Z.,Rajshahi University of Engineering and Technology | Young B.,University of Hong Kong
Thin-Walled Structures | Year: 2013

Cold-formed stainless steel tubular structural members which may experience web crippling failure due to localise concentrated loads or reactions are investigated. A series of tests on fibre-reinforced polymer (FRP) strengthening of cold-formed stainless steel tubular structural members subjected to End-Two-Flange and Interior-Two-Flange loading conditions is presented. The strengthening only applied to a localise area of the members under concentrated load. A total of 58 web crippling tests were conducted. The investigation mainly focused on the effects of different surface treatment, different adhesive, and FRP for strengthening of stainless steel tubular sections against web crippling. The behaviour of stainless steel members strengthened by different widths of FRP plate against web crippling has been also investigated in this study. The test specimens consisted of ferritic stainless steel EN 1.4003 square and rectangular hollow sections. Two different surface treatments were considered. Furthermore, six different adhesives and six different FRPs were also considered in this study. The properties of adhesive and FRP as well as the bonding between the FRP and stainless steel tube have significant influence on the effectiveness of the strengthening. Most of the strengthened specimens were failed by debonding of FRP plates form the stainless steel tubes. Six different failure modes were observed in the tests, namely the adhesion, cohesion, combination of adhesion and cohesion, interlaminar failure of FRP plate, FRP delaminating failure and web crippling failure. The failure loads, failure modes, and the load-web deformation behaviour of the ferritic stainless steel sections are presented in this study. It was found that the web crippling capacity of ferritic stainless steel tubular sections may increase up to 51% using FRP strengthening. © 2012 Elsevier Ltd. All rights reserved.

Hossain A.,Rajshahi University of Engineering and Technology | Yin J.-H.,Hong Kong Polytechnic University
International Journal of Geomechanics | Year: 2014

An interface between compacted soil and a structure is commonly encountered in various geotechnical engineering projects, e.g., soil nails, retaining walls, shallow foundations, pile foundations, and so on. The interface strength depends on the way the soil-structure interface is formed. A cast-in-situ interface is very common in many geotechnical projects. This kind of interface is formed by placing concrete/cement grout over the prepared soil surface. The cement part can be formed over a prepared soil surface in two ways: (1) by normal gravity grouting and (2) by pressure grouting. In this study, a series of interface direct-shear tests was performed between compacted, completely decomposed granite (CDG) soil and cement grout under saturated conditions with different grouting pressures and normal stresses. The behaviors of the shear-stress- displacement curves of the soil-cement interface are similar to those of CDG soil. Grouting pressure and normal stress have influence on the behavior of the soil-cement interface. The failure envelopes for different grouting pressures are observed to be linear. The apparent effective interface friction angles are constant for different grouting pressures. On the other hand, apparent effective adhesion intercepts increase with grouting pressure.When the shear plane is fixed, the apparent effective interface friction angles for different grouting pressures are greater than the effective friction angle of CDG soil under the same normal stresses, which implies that a compacted CDG soil-cement grout interface behaves as a rough interface. The variation in interface shear strength with grouting pressure (grouting-pressure envelope) at the same shear-plane level is approximately linear, and declivities are constant for different normal stresses. A model is proposed for interface shear strength under saturated conditions that considers grouting pressure as an independent variable. The predicted interface shear strength of the proposed model agrees fairly well with the experimental data. © 2014 American Society of Civil Engineers.

Bari M.W.,Rajshahi University of Engineering and Technology | Shahin M.A.,Curtin University Australia
Geotextiles and Geomembranes | Year: 2014

The design of soil consolidation via prefabricated vertical drains (PVDs) has been traditionally carried out deterministically and thus can be misleading due to the ignorance of the uncertainty associated with the inherent variability of soil properties. To treat such uncertainty in the course of design of soil improvement by PVDs, more rational probabilistic methods are necessary. In this paper, a simplified probabilistic method is proposed in which the inherent variability of the coefficient of consolidation, which is the most significant uncertain soil parameter that affects the consolidation process, is considered. An easy-to-use design procedure and charts are provided for routine use by practitioners. © 2013.

Habib M.S.,Rajshahi University of Engineering and Technology | Ahmad R.,Rajshahi University of Engineering and Technology | Hasan M.I.,Rajshahi University of Engineering and Technology
Applied Optics | Year: 2014

An octagonal photonic crystal fiber (PCF) with an elliptical shape in the center core is numerically investigated for residual dispersion compensation in the wavelength range 1460-1675 nm. The designed fiber exhibits flattened negative dispersion over the S + C + L + U wavelength bands and an average dispersion of -465.5 ps/(nm · km) with an absolute dispersion variation of 10.5 ps/(nm · km). In addition, the proposed PCF shows a high birefringence of 2.68 × 10-2at the operating wavelength 1550 nm, which meets the requirement of high birefringence. Moreover, the variation of two air holes in the first ring up to 5% ensures an average dispersion of -491.5 ps/(nm · km) with a dispersion variation of 13 ps/(nm · km), and birefringence reaches up to 3 × 10-2. Furthermore, to evaluate the sensitivity of the fiber dispersion properties, ±5% variation in the optimum parameters is studied. © 2014 Optical Society of America.

Hosen M.A.,Rajshahi University of Engineering and Technology
Ain Shams Engineering Journal | Year: 2014

In this paper, a modified harmonic balance method based an analytical technique has been developed to determine approximate solutions for a strongly nonlinear oscillator with a discontinuous term which is arising from the motion of rigid rod on the surface without slipping. Usually, a set of nonlinear algebraic equations is solved in this method. However, analytical solutions of these algebraic equations are not always possible, especially in the case of a large oscillation. We have been compared the solution results of this method with the numerical solution in order to validate the approach and assess the accuracy of the solutions has been demonstrated and discussed. We found that, a second order modified harmonic balance method works very well for the whole range of initial amplitudes. The advantage of the using method is its simple procedure and gives almost similar results in comparison with the exact solution. © 2014 Production and hosting by Elsevier B.V. on behalf of Ain Shams University.

Hasan M.I.,Rajshahi University of Engineering and Technology | Razzak S.M.A.,Rajshahi University of Engineering and Technology | Habib M.S.,Rajshahi University of Engineering and Technology
Journal of Lightwave Technology | Year: 2014

A residual dispersion compensating octagonal photonic crystal fiber (OPCF), with an elliptical array of circular air-holes in the fiber core region, is proposed. The full-vector finite-element method with perfectly matched layer boundary is used as the analysis tool. It is demonstrated that it is possible to obtain large average negative dispersion of-562.52 ps/(nm · km) over 240 nm and-369.10 ps/(nm · km) over 630 nm wavelength bands for the fast and the slow axis, respectively. In addition to large negative dispersion, ultra-high birefringence, high nonlinearity, and zero-dispersion wavelengths with low confinement loss are also warranted. The proposed OPCFs would be a promising candidate for residual dispersion compensation, supercontinuum generation, and other applications. © 2014 IEEE.

Islam M.R.,Rajshahi University of Engineering and Technology
Computational Intelligence and Neuroscience | Year: 2014

The aim of this work is to propose a new feature and score fusion based iris recognition approach where voting method on Multiple Classifier Selection technique has been applied. Four Discrete Hidden Markov Model classifiers output, that is, left iris based unimodal system, right iris based unimodal system, left-right iris feature fusion based multimodal system, and left-right iris likelihood ratio score fusion based multimodal system, is combined using voting method to achieve the final recognition result. CASIA-IrisV4 database has been used to measure the performance of the proposed system with various dimensions. Experimental results show the versatility of the proposed system of four different classifiers with various dimensions. Finally, recognition accuracy of the proposed system has been compared with existing N hamming distance score fusion approach proposed by Ma et al., log-likelihood ratio score fusion approach proposed by Schmid et al., and single level feature fusion approach proposed by Hollingsworth et al. © 2014 Md. Rabiul Islam.

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