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Search Results: 1 - 10 of 22869 matches for " Md. Al-Mamun "
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Analysis of Optical Properties for Square, Circular and Hexagonal Photonic Crystal Fiber  [PDF]
Md. Bellal Hossain, Abdullah Al-Mamun Bulbul, Md. Abdul Mukit, Etu Podder
Optics and Photonics Journal (OPJ) , 2017, DOI: 10.4236/opj.2017.711021
Abstract: This paper presents four rings square, circular, and hexagonal photonic crystal fiber (PCF) geometry for analyzing different optical properties in a wavelength ranging from 800 nm to 1600 nm. These three types of geometry have been used for analyzing Effective area, Propagation constant, Confinement loss and Waveguide dispersion. Silica glass is chosen as background material and the cladding region is made of four air hole layers. COMSOL Multiphysics (v.5) software is used to simulate these proposed PCF geometries. From the numerical analysis, it is found that the effective area is small for hexagonal PCF geometry and large for square PCF geometry (11.827 μm2, 10.588 μm2 and 9.405 μm2 for square, circular, and hexagonal PCF geometry respectively). From the analysis, the Confinement loss is approximately zero at wavelength ranges from 800 nm to 1250 nm and approximately zero waveguide dispersion is achieved from 900 nm to 1500 nm for all the three PCF structures. Again, negative dispersion approximately 30.354 ps/(nmkm) is achieved for circular PCF structure at the wavelength of 900 nm.
Synthesis, Structural and Physical Properties of Cu1–xZnxFe2O4 Ferrites  [PDF]
Shahida Akhter, Deba Prasad Paul, Md. Abdul Hakim, Dilip Kumar Saha, Md. Al-Mamun, Alhamra Parveen
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.211223
Abstract: Zn substituted Cu-Zn ferrites with a composition Cu1-xZnxFe2O4 have been synthesized by standard double sintering ceramic method and characterized by X-ray diffraction. The single-phase cubic spinel structure of all the samples has been confirmed from X-ray diffraction analyses. The lattice constant is found to increase linearly with the manganese content obeying Vegard’s law. This increase in lattice parameter is explained in terms of the sizes of component ions. It is well known that density plays a key role in controlling the properties of polycrystalline ferrites. The X-ray and bulk densities of the Cu-Zn ferrite is significantly decreased whereas porosity increased with increasing Zn concentration, thereby giving an impression that zinc might be helping in the densification of the materials. SEM micrographs exhibit a decrease in grain size with increasing Zn content. The real part of initial permeability, μ′ increase with increasing Zn contents upto x = 0.5 after that it decreases with higher Zn content.
Effect of Sintering Temperature on Structural and Magnetic Properties of Ni0.55Zn0.45Fe2O4 Ferrites  [PDF]
Robiul Islam, Md Obaidur Rahman, M. Abdul Hakim, Dilip Kumar Saha, Saiduzzaman Saiduzzaman, Saroaut Noor, Md Al-Mamun
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.35048
Abstract: The effect of frequency and sintering temperature on initial permeability of Ni0.55Zn0.45Fe2O4 ferrites have been studied by using an impedance analyzer. The samples were prepared by conventional double sintering ceramic technique using oxide nanoparticles of grain size 30 - 50 nm. Single phase spinal structure has been confirmed for the prepared samples by X-ray diffraction. As the sintering temperatures increase from 1160℃ to 1300℃, the permeability gradually increases. The increase of permeability is ascribed to the increase of density and grain size. Grain size is expected to grow with the increase of sintering temperature. Ferrites with large average grain size posses higher initial permeability. The Curie temperatures determined from temperature dependence of permeability of the samples sintered at different temperatures are found to be Tc = (321 ± 1)℃ and independent of sintering temperature. At Ts = 1300℃, Tc is found to increase substantially which can be explained by the fact that Zn has evaporated from the surface layer.
Alcohol Sensing through Photonic Crystal Fiber at Different Temperature  [PDF]
Etu Podder, Rayhan Habib Jibon, Md. Bellal Hossain, Abdullah Al-Mamun Bulbul, Sagor Biswas, Md. Anamul Kabir
Optics and Photonics Journal (OPJ) , 2018, DOI: 10.4236/opj.2018.810026
Abstract: This paper presents the investigation of relative sensitivity profile of Alcohol through Photonic Crystal fiber at different temperature. Here, 15%, 40%, 60%, 75% of Ethyl Alcohol-water mixture is inserted through the core of Photonic crystal fiber at temperature like 20°C, 25°C and 30°C. COMSOL Multiphysics is used as simulation software and the simulation process is done at wavelength range 600 nm to 1600 nm. From this work, the relative sensitivity is obtained approximately 44, 44.59, 44.85, 45 in percentage at temperature 20°C, 42, 44.2, 44.8, 44.9 in percentage at temperature 25°C, and 42, 43.8, 44.5, 44.85 in percentage at temperature 30°C for 15%, 40%, 60%, 75% of Ethyl Alcohol-water mixture at wavelength 1500 nm respectively. Again, higher sensitivity is achieved when this sensor is operated at lower temperature.
Natural Convection Flow along an Isothermal Vertical Flat Plate with Temperature Dependent Viscosity and Heat Generation
Md. Mamun Molla,Anita Biswas,Abdullah Al-Mamun,Md. Anwar Hossain
Journal of Computational Engineering , 2014, DOI: 10.1155/2014/712147
Abstract: The purpose of this study is to investigate the natural convection laminar flow along an isothermal vertical flat plate immersed in a fluid with viscosity which is the exponential function of fluid temperature in presence of internal heat generation. The governing boundary layer equations are transformed into a nondimensional form and the resulting nonlinear system of partial differential equations is reduced to a convenient form which are solved numerically using an efficient marching order implicit finite difference method with double sweep technique. Numerical results are presented in terms of the velocity and temperature distribution of the fluid as well as the heat transfer characteristics, namely, the wall shear stress and the local and average rate of heat transfer in terms of the local skin-friction coefficient, the local and average Nusselt number for a wide range of the viscosity-variation parameter, heat generation parameter, and the Rayleigh number. Increasing viscosity variation parameter and Rayleigh number lead to increasing the local and average Nusselt number and decreasing the wall shear stress. Wall shear stress and the rate of heat transfer decreased due to the increase of heat generation. 1. Introduction A large number of physical phenomena involve natural convection driven by heat generation. The study of heat generation in moving fluids is important in view of several physical problems such as those dealing with chemical reactions and those concerned with dissociating fluids. Possible heat generation effects may alter the temperature distribution and, therefore, the particle deposition rate. This may occur in such applications related to nuclear reactor cores, fire and combustion modeling, electronic chips, and semiconductor wafers. In fact, the literature is replete with examples dealing with the heat transfer in laminar flow of viscous fluids. Vajravelu and Hadjinicolaou [1] studied the heat transfer characteristics in the laminar boundary layer of a viscous fluid over a linearly stretching continuous surface with viscous dissipation or frictional heating and internal heat generation. In this study, Vajravelu and Hadjinicolaou [1] considered that the volumetric rate of heat generation, [W/m3], should be where is the heat generation constant. The above relation, explained by Vajravelu and Hadjinicolaou [1], is valid as an approximation of the state of some exothermic process and having as the onset temperature. Following Vajravelu and Hadjinicolaou [1], Molla et al. [2–5] investigated the natural convection with heat generation
Outbreak of Egg Drop Syndrome in Bangladesh
Jahangir Alam,Md. Al-Mamun,Mohammed Abdus Samad,Mohammed Rahamat Ullah
International Journal of Biology , 2009, DOI: 10.5539/ijb.v1n1p56
Abstract: An incident alike to egg-drop syndrome (EDS) occurred in commercial egg laying chickens in Gazipur district, Bangladesh from July to November 2005. The chickens showed decreased egg production along with production of shell less and soft shelled eggs when they were at predicted peak production age. Nutritional status, especially crude protein (16.65-18.50%) and calcium (2.15-3.62%) content of the supplied feed was within the range. Virological and serological investigations on causes of decreased egg production and production of soft-shelled and shell less egg by the laying hens revealed that the responsible causative agent is EDS virus. Total seven EDS viruses were isolated from cloacal swab (4), soft-shelled eggs (2) and feces (1). The isolation rate 71.43% (5/7) was higher in second passage than in first passage 28.57% (2/7) in duck embryos. None of the 7 viruses grew in chicken embryo even after second passage. All five flocks tested, were vaccinated against infectious bronchitis and Newcastle disease along with other common vaccines generally used in Bangladesh but not against EDS. Serological investigation revealed that birds in all tested farms (100%) had antibody against EDS virus (in 2 farms in 100% samples and in 3 farms in 80% samples). The source of the virus remained to be determined. To the best of our knowledge, this is the first report of EDS outbreak in Bangladesh. To save poultry industry in Bangladesh from harm of this disease the biosecurity measures should be strictly followed along with vaccination against the disease.
Kinetic adsorption of application of carbon nanotubes for Pb(II) removal from aqueous solution
Kinetic adsorption of application of carbon nanotubes for Pb(II) removal from aqueous solution

Nassereldeen A Kabbashi,Muataz A Atieh,Abdullah Al-Mamun,Mohamed E S Mirghami,MD Z Alam,Noorahayu Yahya,
Nassereldeen A Kabbashi
,Muataz A Atieh,Abdullah Al-Mamun,Mohamed E S Mirghami,MD Z Alam,Noorahayu Yahya

环境科学学报(英文版) , 2009,
Abstract: The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(II) was reach to maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of Pb(II) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). From this study, the results indicates that the highest percentage removal of Pb (96.03%) can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min.
Overview of Malaysian Modularity Manufacturing Practices  [PDF]
Noor Raihani Binti Zainol, Abdullah Al-Mamun, P. Yukthamarani Permarupan
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.37070

Modules and modularity have been popular concepts in operations research instead of products used in Malaysia. In the latest development, Modularity is very important in product design of manufacturing considerations for efficient assembly and complexity to make it better and fasten the process and products. The paper present is a study on overview of modularity products and manufacturing practices in Malaysia such as Traditional Malay House, fordable chair and maintaining services. The process of modularization makes the functional independence as the goal of good design. For the best marketing and end user, industry using modularization process or products leads to creation of product families and uniformity. To make the process of modularity successful, the industry has to ensure that modularity should maintain independence between components and processes in different modules and interchangeability between modules. This paper discusses the modules and modularity which are applied among the manufacturing in the Malaysia in the context of physical products and services.

Responses of Plasma Acetate Metabolism to Hop (Humulus lupulus L.) in Sheep
Mohammad Al-Mamun, Kunio Goto, Sota Chiba, Hiroaki Sano
International Journal of Biological Sciences , 2009,
Abstract: An isotope dilution method using [1-13C]sodium (Na) acetate was conducted to determine the effect of feeding hop (Humulus lupulus L.) residues on plasma acetate metabolism in six adult crossbred sheep. The sheep were fed 63 g/kg BW0.75/d of either mixed hay (MH-diet) of orchardgrass (Dactylis glomerata L.) and reed canarygrass (Phalaris arundinacea L.) at a 60:40 ratio or MH-diet and hop-residues (Hop-diet) at 85:15 ratio with a crossover design for each of 3 week period. The isotope dilution method using single injection of [1-13C]Na acetate was performed thrice; before feeding (BF), 2 h after feeding (2F) and 4 h after feeding (4F), on the 21st day of each dietary treatment. Plasma acetate concentration tended to increase (P= 0.06) and turnover rate was numerically higher (P= 0.16) for MH-diet than Hop-diet. Plasma glucose, NEFA, VFA and lactic acid concentrations were similar between dietary treatments. In both the diets, although plasma concentration of acetate did not change, turnover rate increased significantly (P= 0.02) 2F than BF. Hop-residues did not show any negative impacts on acetate metabolism as well as physiology of animals in the present experimental conditions, hence thereby it could be used as an alternative to MH-diet for rearing sheep.
Statistical optimization of process parameters for the production of citric acid from oil palm empty fruit bunches
N Bari, Z Alam, SA Muyibi, P Jamal, A Al-Mamun
African Journal of Biotechnology , 2010,
Abstract: In this study, optimization of process parameters such as moisture content, incubation temperature and initial pH (fixed) for the improvement of citric acid production from oil palm empty fruit bunches through solid state bioconversion was carried out using traditional one-factor-at-a-time (OFAT) method and response surface methodology (RSM). The possible optimum level of moisture content, incubation temperature, and initial pH were found from the OFAT study to be 70%, 30 - 32oC and 5.5 - 8, respectively. The optimum moisture content of 70.3% (v/w) and incubation temperature of 33.1°C with initial pH of 6.5 gave the maximum production of citric acid (369.16 g/kg of dry EFB). The analysis of variance (ANOVA) of the statistical optimization using central composite design showed that moisture content (p<0.001) and incubation temperature (p<0.0001) as well as the interaction of these two parameters were highly significant for the citric acid production.
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