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Search Results: 1 - 10 of 1870 matches for " Rezaul Karim "
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Mammalian Fauna and Conservational Issues of the Baraiyadhala National Park in Chittagong, Bangladesh  [PDF]
Rezaul Karim, Farid Ahsan
Open Journal of Forestry (OJF) , 2016, DOI: 10.4236/ojf.2016.62011
Abstract: Mammals were studied at the Baraiyadhala National Park, Chittagong from August 2012 to July 2013. Twenty nine species of mammals belonging to 26 genera, 17 families and 9 orders were recorded. Of the recorded species, 2 were primates, 10 rodents, 1 lagomorph (hare), 5 chiropterans (bats), 1 manid, 7 carnivores and 3 ungulates. Rodentia appeared as the largest family contained 10 speices. The overall mammalian population density was 239.12/km2. Irrawardy squirrel (Callosciurus pygerythrus) scored the highest density (112.97/km2) and several species attained the lowest (1/km2 each). Local status (relative abundance) of mammals assessed where 15 (51.72%) species were rare, and according to National Conservation Status, 13 (44.82%) were remarked as threatened species of that area. There were some major threats to the park such as forest fire, encroachment of forest and forest edges by both tribal and landless people, illegal exploitation of forest resources, grazing of livestock and unavailable water reservoirs.
Exact Analytical Solution of K-dV Equation by Extended Direct Method
Rezaul Karim
Pakistan Journal of Social Sciences , 2012,
Abstract: We solve the K-dV equation by an extended version of the direct method due to Clarkson and Kruskal.
Numerical Estimation of Traveling Wave Solution of Two-Dimensional K-dV Equation Using a New Auxiliary Equation Method  [PDF]
Rezaul Karim, Abdul Alim, Laek Sazzad Andallah
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.31004
Abstract:

Korteweg de-Vries (K-dV) has wide applications in physics, engineering and fluid mechanics. In this the Korteweg de-Vries equation with traveling solitary waves and numerical estimation of analytic solutions have been studied. We have found some exact traveling wave solutions with relevant physical parameters using new auxiliary equation method introduced by PANG, BIAN and CHAO. We have solved the set of exact traveling wave solution analytically. Some numerical results of time dependent wave solutions have been presented graphically and discussed. This procedure has a potential to be used in more complex system of many types of K-dV equation.

Dispersion Effect on Traveling Wave Solution of K-dV Equation  [PDF]
Rezaul Karim, Abdul Alim, Laek Sazzad Andallah
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.34044
Abstract:

All solutions of the Korteweg-de Vries(K-dV) equation that are bounded on the real line are physically relevant, depending on the application area of interest. Usually, both analytical and numerical approaches consider solution profiles that are either spatially localized or (quasi) periodic. The development of numerical techniques for obtaining approximate solution of partial differential equations has very much increased in the finite element and finite difference methods. Recently, new auxiliary equation method introduced by PANG, BIAN and CHAO is applied to the analytical solution of K-dV equation and wavelet methods are applied to the numerical solution of partial differential equations. Pioneer works in this direction are those of Beylkin, Dahmen, Jaffard and Glowinski, among others. In this research we employ the new auxiliary equation method to obtain the effect of dispersion term on travelling wave solution of K-dV and their numerical estimation as well. Our approach views the limit behavior as an invariant measure of the fast motion drifted by the slow component, where the known constants of motion of the fast system are employed as slowly evolv- ing observables; averaging equations for the latter lead to computation of the characteristic features of the motion.

Synthesis and Characterizations of Poly(3-hexylthiophene) and Modified Carbon Nanotube Composites
Mohammad Rezaul Karim
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/174353
Abstract: Poly(3-hexylthiophene) and modified (functionalized and silanized) multiwall carbon nanotube (MWNT) nanocomposites have been prepared through in situ polymerization process in chloroform medium with FeCl3 oxidant at room temperature. The composites are characterized through Fourier transfer infrared spectroscopy (FT-IR), Raman, and X-ray diffraction (XRD) measurements to probe the nature of interaction between the moieties. Optical properties of the composites are measured from ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. Conductivity of the composites is followed by four probe techniques to understand the conduction mechanism. The change (if any) in C=C symmetric and antisymmetric stretching frequencies in FT-IR, the shift in G band frequencies in Raman, any alterations in max of UV-Vis, and PL spectroscopic measurements are monitored with modified MWNT loading in the polymer matrix.
Promoting English Teaching in Monolingual Countries:A Study on Students` Language Learning Inclination in the Context of Bangladesh
Ferdous Ahmed,Rezaul Karim
Pakistan Journal of Social Sciences , 2012,
Abstract: With the tremendous advancement and progress of information technology English language has grasped a superior position in all parts of the world as a vital tool of communication. English is considered to be the window of future progress and prosperity. Consequently, much emphasis is attached on the need to master an effective skill in learning this language by those countries of the globe where English is not taught as the First Language. There have been many different teaching methodologies in the history of Teaching English as a Second Language or Foreign Language. However, they all address the same fundamental question: How can we help students to learn the target language efficiently and effectively?. The following study focuses on this question, and investigates the learning preferences of students for effective language learning and teaching. In this respect it is expected that an EL teacher must attach importance on both learner skills and learner assumptions for teaching English in monolingual countries. In promoting this idea, students should be provided with the chance to clarify and assess their inclination in respect of learning English as a foreign language, particularly in reference to definition of objectives in general and awareness of strategies in learning. Moved with the conviction that learners and learners` inclinations are of vital significance in the development of learner autonomy, we interviewed 230 students having English as a remedial course of study and among them 158 were females while 72 were males. The major reason behind this interview was to extract the learners` respective opinions as to how they prefer learning English. In addition, we also had an extensive interview with nearly 23 teachers working at the same university with the same students in order to know their individual impressions regarding the extent of their awareness of their students` learning choices. The data obtained in the backdrop of this interview reveals significant results indicating a necessity for a closer co-operation between students and teachers about how learning activities should be arranged and implemented in the classroom.
A New Approach to Constraint Weight Learning for Variable Ordering in CSPs
Muhammad Rezaul Karim
Computer Science , 2013, DOI: 10.1109/CEC.2014.6900262
Abstract: A Constraint Satisfaction Problem (CSP) is a framework used for modeling and solving constrained problems. Tree-search algorithms like backtracking try to construct a solution to a CSP by selecting the variables of the problem one after another. The order in which these algorithm select the variables potentially have significant impact on the search performance. Various heuristics have been proposed for choosing good variable ordering. Many powerful variable ordering heuristics weigh the constraints first and then utilize the weights for selecting good order of the variables. Constraint weighting are basically employed to identify global bottlenecks in a CSP. In this paper, we propose a new approach for learning weights for the constraints using competitive coevolutionary Genetic Algorithm (GA). Weights learned by the coevolutionary GA later help to make better choices for the first few variables in a search. In the competitive coevolutionary GA, constraints and candidate solutions for a CSP evolve together through an inverse fitness interaction process. We have conducted experiments on several random, quasi-random and patterned instances to measure the efficiency of the proposed approach. The results and analysis show that the proposed approach is good at learning weights to distinguish the hard constraints for quasi-random instances and forced satisfiable random instances generated with the Model RB. For other type of instances, RNDI still seems to be the best approach as our experiments show.
Heat Generation Effects on MHD Natural Convection Flow along a Vertical Wavy Surface with Variable Thermal Conductivity  [PDF]
Md Abdul Alim, Md Rezaul Karim, Md Miraj Akand
American Journal of Computational Mathematics (AJCM) , 2012, DOI: 10.4236/ajcm.2012.21005
Abstract: The heat generation effects on magnetohydrodynamic(MHD) natural convection flow along a vertical wavy surface with variable thermal conductivity have been investigated. The governing boundary layer equations are first transformed into a non-dimensional form using suitable set of dimensionless variables. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as Keller-box scheme. The numerical results of the surface shear stress in terms of skin friction coefficient and the rate of heat transfer in terms of local Nusselt number, the stream lines as well as the isotherms are shown graphically for a selection of parameters set consisting of thermal conductivity variation parameter, heat generation parameter Q, magnetic parameter M and Prandtl number Pr. Comparison of numerical results of present work with other published data has been shown in table.
Generalized Minimum Perpendicular Distance Square Method of Estimation  [PDF]
Rezaul Karim, Morshed Alam, M. M. H. Chowdhury, Forhad Hossain
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312266
Abstract: In case of heteroscedasticity, a Generalized Minimum Perpendicular Distance Square (GMPDS) method has been suggested instead of traditionally used Generalized Least Square (GLS) method to fit a regression line, with an aim to get a better fitted regression line, so that the estimated line will be closest one to the observed points. Mathematical form of the estimator for the parameters has been presented. A logical argument behind the relationship between the slopes of the lines and has been placed.
Competitive Ability of Different Weed Species
S.M. Rezaul Karim
Journal of Agronomy , 2002,
Abstract: A range of weed species were grown in all combinations with four crop species (wheat, barley, bean and oilseed rape) under field conditions of 1990-91. The weeds were ranked on the basis of their competitive abilities. The degree to which competitive ability was specific to particular combination of crops and weed species was examined. Two indices-crop equivalent and aggressivity were compared to measure the competitive ability of the weeds. Based on aggressivity the ranking order of the weeds for their competitive abilities was, cleavers (Galium aparine L.)> wild oats (Avena fatua L.)> field speedwell (Veronica persica Poir.)> common chickweed (Stellaria media L. Cyrill.)> scented mayweed (Matricaria recutita). The ranking of the weeds varied depending on the associated crop and at different growth stages. There was a poor correlation between crop equivalent and aggressivity.
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