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Search Results: 1 - 10 of 6498 matches for " Md. Shafiqul Islam "
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Numerical Solutions of a Class of Second Order Boundary Value Problems on Using Bernoulli Polynomials  [PDF]
Md. Shafiqul Islam, Afroza Shirin
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.29147
Abstract: The aim of this paper is to find the numerical solutions of the second order linear and nonlinear differential equations with Dirichlet, Neumann and Robin boundary conditions. We use the Bernoulli polynomials as linear combination to the approximate solutions of 2nd order boundary value problems. Here the Bernoulli polynomials over the interval [0,1] are chosen as trial functions so that care has been taken to satisfy the corresponding homogeneous form of the Dirichlet boundary conditions in the Galerkin weighted residual method. In addition to that the given differential equation over arbitrary finite domain [a,b] and the boundary conditions are converted into its equivalent form over the interval [0,1]. All the formulas are verified by considering numerical examples. The approximate solutions are compared with the exact solutions, and also with the solutions of the existing methods. A reliable good accuracy is obtained in all cases.
Comparison of Classical Method, Extension Principle and α-Cuts and Interval Arithmetic Method in Solving System of Fuzzy Linear Equations  [PDF]
Sahidul Islam, Md. Saiduzzaman, Md. Shafiqul Islam, Abeda Sultana
American Journal of Computational Mathematics (AJCM) , 2019, DOI: 10.4236/ajcm.2019.91001
Abstract: The system of linear equations plays a vital role in real life problems such as optimization, economics, and engineering. The parameters of the system of linear equations are modeled by taking the experimental or observation data. So the parameters of the system actually contain uncertainty rather than the crisp one. The uncertainties may be considered in term of interval or fuzzy numbers. In this paper, a detailed study of three solution techniques namely Classical Method, Extension Principle method and α-cuts and interval Arithmetic Method to solve the system of fuzzy linear equations has been done. Appropriate applications are given to illustrate each technique. Then we discuss the comparison of the different methods numerically and graphically.
Performance Analysis of Optical Wireless Communication System Employing Neuro-Fuzzy Based Spot-Diffusing Techniques  [PDF]
Shamim Al Mamun, M. Shamim Kaiser, Muhammad R Ahmed, Md. Shafiqul Islam, Md. Imdadul Islam
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.53B2048
Abstract: The spot-diffusing technique provides better performance compared to conventional diffuse system for indoor optical-wireless communication (OWC) system. In this paper, the performance of an OW spot-diffusing communication system using Neuro-Fuzzy (NF) adaptive multi-beam transmitter configuration has been proposed. The multi-beam transmitter generates multiple spots pointed in different directions, hence, forming a matrix of diffusing spots based on position of the receiver and receiver mobility. Regardless of the position of the transmitter and receiver, NF controller target the spots adaptively at the best locations and allocates optimal power to the spots and beam angle are adapted in order to achieve better signal-to-noise plus interference ratio (SNIR). Maximum ratio combining (MRC) is used in the imaging receiver. The proposed OW spot-diffusing communication system is compared with other spot-beam diffusion methods proposed in literature. Performance evaluation revels that the proposed NF based OW spot-diffusing communication system outperforms other spot-beam diffusion methods.
Numerical Solutions of Fredholm Integral Equations Using Bernstein Polynomials
Afroza Shirin,Md. Shafiqul Islam
Computer Science , 2013, DOI: 10.3329/jsr.v2i2.4483
Abstract: In this paper, Bernstein piecewise polynomials are used to solve the integral equations numerically. A matrix formulation is given for a non-singular linear Fredholm Integral Equation by the technique of Galerkin method. In the Galerkin method, the Bernstein polynomials are used as the approximation of basis functions. Examples are considered to verify the effectiveness of the proposed derivations, and the numerical solutions guarantee the desired accuracy.
Photocatalytic Degradation of p-Nitrophenol (PNP) in Aqueous Suspension of TiO2  [PDF]
Shafiqul Islam, Sumon Kumar Bormon, Md. Nadim, Kamrul Hossain, Ahsan Habib, Tajmeri Selima Akhter Islam
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.58057
Abstract: The effects of initial concentrations of PNP, doses of TiO2, cations and anions have been investigated to find out the conditions for the maximum degradation of PNP in presence of 254 nm UV light. The rate of photocatalytic degradation of PNP was increased with increasing TiO2 dose until the dose concentration reached at a value 0.4 g/100 mL. Further increase of TiO2 decreased the degradation. The maximum degradation of PNP was found with the catalyst dose 0.4 g/100 mL at pH 3. The degradation of PNP was decreased with increasing of PNP concentration. About 90% degradation of PNP was observed when 1.0 × 10﹣4 M PNP was irradiated for 2 hours in 0.4 g/100 mL of TiO2 suspension. The effect of Cu(II) and Fe(II) ions on the degradation was also investigated. Addition of Cu(II) ions enhances the percent degradation but excess of Cu(II) ions decreases the degradation. Under the same experimental conditions, the presence of \"\" and \"\" is found to be detrimental to the photodegradation of PNP. Hydrogen ion concentration of reaction mixture was found to increase continuously during photodegradation suggesting mineralization of PNP.
Biological Evaluation of New Schiff Bases: Synthesized from 4-Amino-3,5-dimethyl-1,2,4-triazole, Phenathroline and Bipyridine Dicarboxaldehydes  [PDF]
Md. Shafiqul Islam, Mohammad R. Karim, William Boadi, Seyi Falekun, Aminul H. Miza
Advances in Biological Chemistry (ABC) , 2016, DOI: 10.4236/abc.2016.66016
Abstract: Four new Schiff bases with promising anticancer activity have been synthesized from 4-amino-3,5-dimethyl-1,2,4-triazole and di-pyridyl-aldehydes. Structures have been established by various spectroscopic methods. The compounds were tested in vitro to study their cytotoxicity and anti-oxidative activity in human lung carcinoma (A549), breast carcinoma (BT549), prostate adenocarcinoma (PC3) and mouse preadipocytes (3T3-L1) cells. Compound 1 was found to increase Glutathione (GSH) level slightly in all four cell lines. Compound 4 showed better selectivity and cytotoxicity against both BT549 and A549 cells compared to the anticancer drug tamoxifen. With the exception of compound 4 which reduced GSH levels in A549 and BT549, all other compounds maintained GSH levels in comparison to their respective controls.
Some Novel Schiff Bases from Pyruvic Acid with Amines Containing N & S Donor Atoms: Synthesis, Spectral Studies and X-Ray Crystal Structures  [PDF]
Abdul Azim Jambol, Malai Haniti Sheikh Abdul Hamid, Aminul Huq Mirza, Md. Shafiqul Islam, Mohammad Rezaul Karim
International Journal of Organic Chemistry (IJOC) , 2017, DOI: 10.4236/ijoc.2017.71005
Abstract: Four Schiff bases, from pyruvic acid (1) with amines containing N and S donor atoms, thiocarbohydrazide (2, 61%), 2-methyl-3-thiosemicarbazide (3, 26%), S-benzyldithiocarbazate (4, 51%) and S-n-octyldithiocarbazate (5, 63%) have been successfully synthesized. The conventional method was used and a series of novel linear and cyclic Schiff bases were obtained with or without catalyst. All the Schiff bases were fully characterized by CHN elemental analysis, FT-IR, 1H & 13C NMR, EI-MS and two of the Schiff bases were further characterized by X-ray crystallographic structure analysis. Compound 2 crystallizes in the triclinic space group P-1 and unit cell dimensions are: a = 4.1777(8), b = 5.9538(11), c = 13.458(3) Å, α = 92.759(6), β = 90.813(6), γ = 100.040(6)°, R1 = 0.0439. Compound 3 crystallizes in the orthorhombic space group P n a 2(1) and unit cell dimensions are: a = 5.5992(2), b = 11.3962(5), c = 10.6473(5), α = 92.759(6), β = 90.813(6), γ = 100.040(6)°, R1 = 0.0285. Compounds 2 and 3 were obtained as cyclic Schiff bases which are triazine derivatives.
Invariant densities of random maps have lower bounds on their supports
Pawe Góra,Abraham Boyarsky,Md Shafiqul Islam
International Journal of Stochastic Analysis , 2006, DOI: 10.1155/jamsa/2006/79175
Abstract: A random map is a discrete-time dynamical system in which one of a number of transformations is randomly selected and applied at each iteration of the process. The asymptotic properties of a random map are described by its invariant densities. If Pelikan's average expanding condition is satisfied, then the random map has invariant densities. For individual maps, piecewise expanding is sufficient to establish many important properties of the invariant densities, in particular, the fact that the densities are bounded away from 0 on their supports. It is of interest to see if this property is transferred to random maps satisfying Pelikan's condition. We show that if all the maps constituting the random map are piecewise expanding, then the same result is true. However, if one or more of the maps are not expanding, this may not be true: we present an example where Pelikan's condition is satisfied, but not all the maps are piecewise expanding, and show that the invariant density is not separated from 0.
A generalization of Straube's theorem: existence of absolutely continuous invariant measures for random maps
Md. Shafiqul Islam,Pawel Góra,Abraham Boyarsky
International Journal of Stochastic Analysis , 2005, DOI: 10.1155/jamsa.2005.133
Abstract: A random map is a discrete-time dynamical system in which one of a number of transformations is randomly selected and applied at each iteration of the process. In this paper, we study random maps. The main result provides a necessary and sufficient condition for the existence of absolutely continuous invariant measure for a random map with constant probabilities and position-dependent probabilities.
Mohammed Ashaque Meah,Ahmad Izani M Ismail,Md. Fazlul Karim,Md. Shafiqul Islam
Science of Tsunami Hazards , 2012,
Abstract: A new approach is developed to simulate the effect of far field tsunami in a limited area model domain where the coastal and Island boundaries are curvilinear in nature and the bending is high. The model is designed in a boundary fitted curvilinear grid system. To simulate the effect of far field tsunami, it is considered that the tsunami source is located far away from the model domain. The coastal and island boundaries and the other open boundaries of the model domain are represented by some functions so as to generate the boundary fitted grids. To use the regular finite difference scheme a transformation is used so that the physical domain is transformed into a rectangular one. The transformed shallow water equations are then solved in the transformed domain. The response of the tsunami source due to 26 December 2004 Indonesian tsunami is computed along the western open boundary of the model domain. Based on the response of the tsunami source, an appropriate boundary condition is formulated to simulate the effect of far field tsunami along the coastal belt. All simulations show excellent agreement with the observed data.
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