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Effects of Hydromagnetic and Thermophoresis of Unsteady Forced Convection Boundary Layer Flow over Flat Plates

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Journal of Applied Mathematics and Physics 2016年第9期4卷 1756-1776页

作者： md. Jashim Uddin md. yeakub ali Department of Mathematics Chittagong University of Engineering & Technology Chittagong-4349 Bangladesh Department of Electrical & Electronic Engineering International Islamic University Chittagong Chittagong-4318 Bangladesh

In this paper, we analyze unsteady two dimensional hydromagnetic forced convection boundary layer flow of a viscous incompressible fluid along flat plates with thermophoresis. The potential flow velocity has been taken as a function of the distance x and time t. The governing partial differential equations are transformed to ordinary differential equation by applying local similarity transformation. The resulting similarity equations are then solved numerically for unsteady case, applying Nachtsheim-Swigert shooting iteration technique with six order Runge-Kutta method. The variations in fluid velocity, fluid temperature and species concentration are displayed graphically and discussed for different material parameters entering into the analysis. The effects of the pertinent parameters on the skin-friction coefficient, wall heat transfer coefficient and wall deposition flux rate are also displayed in tabulated form and discussed them from the physical point of view. An analysis of the obtained results shows that the flow field is influenced appreciably by the magnetic field parameter and the thermophoresis particle deposition.

关键词： Forced Convection Hydromagnetic Field Similarity Solution Unsteady Thermophoresis

Spin Glass Phase Exists in the Random Weak Disorder for the Villain Model

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Journal of Applied Mathematics and Physics 2014年第13期2卷 1190-1195页

作者： md. yeakub ali Sunil Dhar Department of Mathematics Chittagong University of Engineering and Technology Chittagong Bangladesh

In this work we have studied non random Villain model by introducing simple defects to calculate degeneracies of the first excited states using Pfaffian approach through a perturbation theory. The distributions of excitations of the ground states are displayed graphically. The results are indicated that spin glass occurs in the weak disorder for the Villain model. At the concentration of defect bonds p=0.03, the distribution behaves in the same manner as for p=0.5 for different sizes of lattice. The latest result of the spin glass is presented in this paper.

关键词： Spin Glass First Excitations Distribution Square Lattice

Unsteady Mixed Convection Slip Flow around a Stretching Sheet in Porous Medium

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Journal of Applied Mathematics and Physics 2022年第10期10卷 3016-3036页

作者： md. Aminul Islam md. yeakub ali Romena Akter S. M. Osman Gani Department of Mathematics Chittagong University of Engineering & Technology Chattogram Bangladesh Department of Natural Science Port City International University Chattogram Bangladesh

The heat and mass transfer of unsteady MHD two-dimensional mixed convection boundary layer flow over an exponentially porous stretching sheet is presented in this paper. Multiple slip conditions, radiation, suction or blowing, heat generation or absorption along with magnetism and porous medium are incorporated. We reduce the leading equations which are partial differential equations into a family of ordinary differential equations that are non-linear using a set of similarity transformations. The resulting equations with coupled boundary conditions are solved numerically with the aid of bvp4c solver with MATLAB package. The impacts of several non-dimensional governing parameters on the flow fields such as velocity, temperature and concentration profiles along with friction coefficient, temperature gradient and concentration gradient are portrayed graphically and discussed in detail. The result indicates that the magnetic parameter decreases the skin friction coefficient. Thermal boundary layer thickness reduces with increasing radiation parameters and enhances with increasing Prandtl number. It is also observed that the thermal slip parameter depreciates the heat transfer rate and the mass slip parameter diminishes the mass transfer rate. A comparison has been made between the current results and the numerical results of previous studies and observed a very close good agreement.

关键词： Mixed Convection Porous Medium Slips Boundary Conditions Suction/Blowing

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Open Journal of Fluid Dynamics 2016年第4期6卷 279-302页

作者： Mohammed Nasir Uddin md. yeakub ali N. M. Ridwan Zahed md. Jashim Uddin Department of Mathematics Chittagong University of Engineering & Technology Chittagong Bangladesh Department of Electrical & Electronic Engineering International Islamic University Chittagong Chittagong Bangladesh

Unsteady mixed convective boundary layer flow of viscous incompressible fluid along isothermal horizontal plate is analyzed through Similarity Solutions. The governing partial differential equations are transformed into ordinary differential equations using the similarity transformation and solved numerically along with shooting technique. The flow field for the fluid velocity, temperature and concentration at the plate surface are significantly influenced by the governing parameters such as unsteadiness parameter, permeability parameter, Prandtl number, Schmidt number and the other driving parameters. The results show that both fluid velocity and temperature decrease but no significant effect on concentration for the increasing values of Prandtl number. It is also exposed that velocity and concentration is higher at lower Schmidt number for low Prandtl fluid. Finally, the dependency of the Skin-friction co-efficient, Nusselt number and Sherwood number, which are of physical interest, are also illustrated in tabular form for the governing parameters.

关键词： Similarity Solution Unsteady Flow Mixed Convection Boundary Layer Flow Horizontal Plate Incompressible Fluid

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Open Journal of Fluid Dynamics 2015年第4期5卷 391-406页

作者： md. yeakub ali Mohammed Nasir Uddin md. Jasim Uddin N. M. Ridwan Zahed Department of Mathematics Chittagong University of Engineering & Technology Chittagong Bangladesh

Similarity solution of unsteady convective boundary layer flow along isothermal vertical plate with porous medium is analyzed. The plate surface is reactive with the fluid and generates inert specie which diffuses inside the boundary. The flux of the specie at the plate is proportional to specie concentration at the plate. The governing equations of continuity, momentum, energy and specie diffusion are transformed into ordinary differential equation by using the similarity transformation and solved numerically by using free parameter method along with shooting technique. The dimensionless velocity, temperature and concentration profiles are obtained and presented through figures for different parameters entering into the problem. The local Skin-friction co-efficient, Nusselt number and Sherwood number at the plate for physical interest are also discussed through tables.

关键词： Similarity Solution Unsteady Flow Porous Medium Convective Boundary Layer Flow Vertical Plate

Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh

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Acta Oceanologica Sinica 2019年第6期38卷 100-116页

作者： Gour Chandra Paul md. Emran ali Department of Mathematics University of RajshahiRajshahi 6205Bangladesh Department of Textile Engineering Northern University BangladeshDhaka 1230Bangladesh

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M2 along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,

关键词： shallow water equations method of lines higher order finite difference approximation method surge nested scheme

Surface Morphology and Thermo-Electrical Energy Analysis of Polyaniline (PANI) Incorporated Cotton Fabric

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Energy Engineering 2024年第1期121卷 1-12页

作者： md.Shohan Parvez md.Mustafizur Rahman Mahendran Samykano Mohammad yeakub ali Automotive Engineering Research Group Faculty of Mechanical and Automotive Engineering TechnologyUniversiti Malaysia Pahang Al-Sultan AbdullahPekanMalaysia Department of Textile Engineering Khulna University of Engineering&Technology(KUET)KhulnaBangladesh Centre for Research in Advanced Fluid and Processes(CARIFF) Universiti Malaysia Pahang Al-Sultan AbdullahLebuhraya Tun RazakGambangMalaysia Mechanical Engineering Programme Area Faculty of EngineeringUniversiti Teknologi BruneiBruneiDarussalam

With the exponential development in wearable electronics,a significant paradigm shift is observed from rigid electronics to flexible wearable ***(PANI)is considered as a dominant material in this sector,as it is endowed with the optical properties of both metal and ***,its widespread application got delineated because of its irregular rigid form,level of conductivity,and precise choice of *** PANI in textile materials can generate promising functionality for wearable *** research work employed a straightforward in-situ chemical oxidative polymerization to synthesize PANI on Cotton fabric surfaces with varying dopant(HCl)***-treatment using NaOH is implemented to improve the conductivity of the fabric surface by increasing the monomer *** research explores the morphological and structural analysis employing SEM,FTIR and *** surface resistivity was measured using a digital multimeter,and thermal stability is measured using *** successful polymerization,a homogenous coating layer is *** is revealed that the simple pre-treatment technique significantly reduces the surface resistivity of Cotton fabric to 1.27 kΩ/cm with increasing acid concentration and thermal *** electro-thermal energy can also reach up to 38.2°C within 50 s with a deployed voltage of 15 *** modified fabric is anticipated to be used in thermal regulation,supercapacitor,sensor,UV shielding,antimicrobial and other prospective functional applications.

关键词： Polyaniline cotton in-situ polymerization SEM TGA heating fabric

Selection of Rice Genotypes for Salinity Tolerance Through Morpho-Biochemical Assessment

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Rice science 2014年第5期21卷 288-298页

作者： md. Nasim ali Bhaswati GHOSH Saikat GANTAIT Somsubhra CHAKRABORTY Department of Agricultural Biotechnology Faculty Centre for Integrated Rural Development and Management School of Agriculture and Rural Development Ramakrishna Mission Vivekananda UniversityRamakrishna Mission Ashrama NarendrapurKolkata 700103 India Department of Crop Science Faculty of Agriculture University Putra Malaysia43400 Serdang SelangorMalaysia Sasya Shyamala Krishi Vigyan Kendra Ramakrishna Mission Vivekananda UniversityArapanch Sonarpur Kolkata 700150 India

The present study reported the morpho-biochemical evaluation of 15 selected rice genotypes for salt tolerance at the seedling stage. Growth parameters including shoot length, root length, plant biomass, plant turgid weight, plant dry weight along with relative water content were measured after exposure to saline solution （with electrical conductivity value of 12 dS/m）. Genotypes, showing significant differential responses towards salinity in the fields, were assessed through 14 salinity-linked morpho-biochemical attributes, measured at 14 d after exposure of seedling in saline nutrient solution. Relative water content, chlorophyll a/b, peroxidase activity and plant biomass were identified as potential indicators of salt tolerance. Principal component analysis and successive Hierarchical clustering using Euclidean distance revealed that Talmugur, Gheus, Ghunsi, Langalmura, Sabitapalui, and Sholerpona were promising genotypes for further breeding programmes in rice. The maximum Euclidean distance was plotted between Thavallakanan and Talmugur （7.49）, followed by Thavallakanan and Langalmura （6.82）, indicating these combinations may be exploited as parental lines in hybridization programmes to develop salinity tolerant variety.

关键词： chlorophyll content electrical conductivity Oryza sativa L. peroxidase activity prolinecontent relative water content salinity tolerance sugar content superoxide dismutase

Vector Autoregressive （VAR） Modeling and Projection of DSE

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Chinese Business Review 2015年第6期14卷 273-289页

作者： Ahammad Hossain md. Kamruzzaman md. Ayub ali Varendra University Rajshahi Bangladesh University of Rajshahi Rajshahi Bangladesh

In this paper, vector autoregressive （VAR） models have been recognized for the selected indicators of Dhaka stock exchange （DSE）. Bangladesh uses the micro economic variables, such as stock trade, invested stock capital, stock volume, current market value, and DSE general indexes which have the direct impact on DSE prices. The data were collected for the period from June 2004 to July 2013 as the basis on daily scale. But to get the maximum explorative information and reduction of volatility, the data have been transformed to the monthly scale. The outliers and extreme values of the study variables are detected through box and whisker plot. To detect the unit root property of the study variables, various unit root tests have been applied. The forecast performance of the different VAR models is compared to have the minimum residual. Moreover, the dynamics of this financial market is analyzed through Granger causality and impulse response analysis.

关键词： vector autoregressive (VAR) model impulse response analysis Granger causality