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Search Results: 1 - 10 of 139940 matches for " K. Hossain "
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Synthesis and Magnetic Properties of Ba2Ni2–xZnxFe12O22  [PDF]
Sajal Chandra Mazumdar, A. K. M. Akther Hossain
World Journal of Condensed Matter Physics (WJCMP) , 2012, DOI: 10.4236/wjcmp.2012.24030
Abstract: Y-type hexagonal ferrites with the nominal chemical composition Ba2Ni2-xZnxFe12O22 (0.0 ≤ x ≤ 0.6 with a step of 0.1) have been synthesized by the conventional solid state reaction method and sintered in the temperature range 1150℃-1250℃ to study their structural and magnetic properties. The aim of the present work is to increase the magnetic properties of Y-type hexaferrites by Zn substitution. X-ray diffraction analysis confirms the formation of the hexagonal phase. The effect of chemical composition on the lattice parameter, density and porosity is studied. The lattice parameter increases with Zn substitution. The density increases with Zn substitution up to a certain level and after that density decreases. The ac magnetic properties of the hexaferrites sintered at temperature 1200℃ are characterized within the frequency range 100 kHz -120 MHz. The real part (μi') of the complex initial permeability for different compositions indicates that μi' decreases with increase in frequency. The permeability increases with the increase in Zn content, reaches a maximum value and then decreases with further increase in Zn content. Magnetization has been measured using the Superconducting Quantum Interference Device (SQUID) magnetometer. The saturation magnetization is observed to be maximum at x = 0.1 and then decreases with Zn content for x > 0.1. From the M-H curve it is clear that at room temperature the polycrystalline Ba2Ni2-xZnxFe12O22 compositions are in ferrimagnetic state.
Three Dimensional Numerical Modeling of Flow and Pollutant Transport in a Flooding Area of 2008 US Midwest Flood  [PDF]
Xiaobo Chao, A. K. M. Azad Hossain, Yafei Jia
American Journal of Climate Change (AJCC) , 2013, DOI: 10.4236/ajcc.2013.22012
Abstract: This paper presents the development and application of a three-dimensional numerical model for simulating the flow field and pollutant transport in a flood zone near the confluence of the Mississippi River and Iowa River during the US Midwest Flood in 2008. Due to a prolonged precipitation event, a levee along the Iowa River just upstream of Oakville, Iowa broke, and the small town was completely flooded for a couple of weeks. During this period, the high water level in the flood zone reached about 2.5 metersabove the ground, and wind was the major force for the flow circulation. It was observed that some pollutants were leaked from the residential and farming facilities and transported into the flood zone. Leaking of pollutants from these facilities was reported by different news media during the flood and was identified using high resolution satellite imagery. The developed 3D numerical model was first validated using experimental measurements, and then applied to the flood inundated zone in Oakville for simulating the unsteady hydrodynamics and pollutant transport. The simulated pollutant distributions were generally in good agreement with the observed data obtained from satellite imagery.
A Finite Element Analysis on MHD Free Convection Flow in Open Square Cavity Containing Heated Circular Cylinder  [PDF]
Sheikh Anwar Hossain, M. A. Alim, S. K. Saha
American Journal of Computational Mathematics (AJCM) , 2015, DOI: 10.4236/ajcm.2015.51003
Abstract: The problem of Magnetohydrodynamic (MHD) free convection heat transfer in a square open cavity containing a heated circular cylinder at the centre has been investigated in this work. As boundary conditions of the cavity, the left vertical wall is kept at a constant heat flux, bottom and top walls are kept at different high and low temperature respectively. The remaining side wall is open. Finite element analysis based on Galerkin weighted Residual approach is used to visualize the temperature distribution and fluid flow solving two-dimensional governing mass, momentum and energy equations for steady state, natural convection flow in presence of magnetic field in side an open square cavity. A uniformly heated circular cylinder is located at the centre of the cavity. The object of this study is to describe the effects of MHD on the thermal fields and flow in presence of such heated circular cylinder by visualization of graph. The investigations are conducted for different values of Rayleigh number (Ra) and Hartmann number (Ha). The results show that the temperature field and flow pattern are significantly dependent on the above mentioned parameters.
Numerical Modeling of Sediment Transport and Its Effect on Algal Biomass Distribution in Lake Pontchartrain Due to Flood Release from Bonnet Carré Spillway  [PDF]
Xiaobo Chao, Yafei Jia, A. K. M. Azad Hossain
Journal of Geoscience and Environment Protection (GEP) , 2016, DOI: 10.4236/gep.2016.49006
Abstract: In order to protect the city of New Orleans from the Mississippi River flooding, the Bonnet Carré Spillway (BCS) was constructed from 1929 to 1936 to divert flood water from the river into Lake Pontchartrain and then into the Gulf of Mexico. During the BCS opening for flood release, large amounts of freshwater, nutrients, sediment, etc. were discharged into Lake Pontchartrain, and caused a lot of environmental problems. To evaluate the environmental impacts of the flood water on lake ecosystems, a two-dimensional numerical model was developed based on CCHE2D and applied to simulate the flow circulation, sediment transport and algal biomass distribution in Lake Pontchartrain. The effect of sediment concentration on the growth of algae was considered in the model. The numerical model was calibrated using field measured data provided by USGS, and then it was validated by the BCS Opening Event in 1997. The simulated results were generally in good agreement with filed data and satellite imagery. The field observation and numerical model show that during the spillway opening for flood release, the sediment concentration is very high, which greatly restricts the growth of algae, so there is no algal bloom observed in the lake. After the closure of BCS, the sediment concentration in the lake reduces gradually, and the nutrient concentration of the lake is still high. Under these conditions, numerical results and satellite imagery showed that the chlorophyll concentration was high and algal bloom might occur.
The Central Cattle Breeding and Dairy Farm, Bangladesh waste contributes in emergence and spread of aminoglycoside-resistant bacteria  [PDF]
Sohel Ahmed, M. Ibrahim Hossain, Tareq Hossan, K. M. Rokibul Islam, orhan Uddin, M. Badier Rahman, M. Anwar Hossain
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.42A038
Aminoglycosides are one of the categories of antibiotics most frequently used in treating several cattle diseases at the Central Cattle Breeding and Dairy Farm (CCBDF), Savar,Dhaka,Bangladesh. Untreated veterinary clinical healthcare waste (VCHW) of diseased cattle at CCBDF which directly disposed to surrounding may contribute to the antibiotic resistant bacteria pollution (ARB) pollution. The investigation analyses the role of VCHW of CCBDF in spreading ARB. Here we studied1) veterinary clinical data and antibiotics treatment history; 2) total and resistant bacteria counts in fecal samples of healthy and diseased cattles as well as VCHW of CCBDF; and 3) finally, data analysis to estimate the burden of VCHW of CCBDF in the pollution of environment with aminoglycoside antibiotics resistant bacteria. The results conclusively demonstrate the spread of 3 different aminoglycoside antibiotics, namely genta- mycin, kanamycin and streptomycin resistant bacte- ria in the surrounding environment alarmingly with high significant value (p < 0.01 - 0.05). This study re- veals the risks to the cattle as well as public health posed by the random VCHW disposal at the CCBDF, Bangladesh.
Heat transfer in a rectangular enclosure with baffles
M. R. Asif,M. S. Hossain,K. A. Hossain
Journal of Engineering and Applied Sciences , 2011,
Abstract: A numerical study has been carried out to investigate the mixed convective two dimensional flows in a vertical enclosure with heated baffles on side walls. All walls are assumed to be adiabatic, but baffles are considered as isothermally heated. Thus, cold flow is imposed through an opening at the bottom of the left wall and by taking heat from the baffles the fluid becomes heated and exits through outlet at the top of the right wall of the enclosure. Heated baffles are placed both at the left and right wall of the enclosure. The present study simulates a practical system such as a silencer. The consequent mathematical model is governed by the coupled equations of mass, momentum and energy and these equations are discritized. The discritized equations with specified boundary conditions are sought by Successive under Relaxation (SUR) method. A wide range of pertinent parameters such as Reynolds number 50 ≤ Re ≤ 300, Richardson number 0 ≤ Ri ≤ 10 and Prandtl number 0.01 ≤ Pr ≤ 2.0 are considered in the present study. Various results such as the streamlines, isotherms, heat transfer rates in terms of the average Nusselt number and temperature and also heating efficiency in the enclosure are presented for different parameters. It is observed that Maximum heating efficiency is found at higher value of Reynolds and Richardson number.
An Econometric Analysis for CO2 Emissions, Energy Consumption, Economic Growth, Foreign Trade and Urbanization of Japan  [PDF]
Sharif Hossain
Low Carbon Economy (LCE) , 2012, DOI: 10.4236/lce.2012.323013
Abstract: This paper examines the dynamic causal relationship between carbon dioxide emissions, energy consumption, economic growth, foreign trade and urbanization using time series data for the period of 1960-2009. Short-run unidirectional causalities are found from energy consumption and trade openness to carbon dioxide emissions, from trade openness to energy consumption, from carbon dioxide emissions to economic growth, and from economic growth to trade openness. The test results also support the evidence of existence of long-run relationship among the variables in the form of Equation (1) which also conform the results of bounds and Johansen conintegration tests. It is found that over time higher energy consumption in Japan gives rise to more carbon dioxide emissions as a result the environment will be polluted more. But in respect of economic growth, trade openness and urbanization the environmental quality is found to be normal good in the long-run.
Application of Resource Efficient and Cleaner Production (RECP) in the Energy Intensive Industry to Promote Low Carbon Industrial Development in Bangladesh  [PDF]
Tahazzud Hossain
Low Carbon Economy (LCE) , 2015, DOI: 10.4236/lce.2015.63009
Abstract: The consumption of natural resources (e.g. raw material, water & energy) in the industries is bringing welfare to the society but per unit of product from the industry is linked with the generation of environmental pollutants and emissions. Resource constraints and climate crisis have come into focus globally; particularly it has become one of the major concerns in the Asia Pacific region. At present, the countries in the Asia Pacific use resources three times greater than the rest of the world to generate one unit of GDP. These countries are more vulnerable to the impacts of resource constraints and climate change. Resource Efficient and Cleaner Production (RECP) has come as a preventive environmental measure to facilitate pollution prevention and reduce carbon intensity per unit of products along with financial profit of the industry. Bangladesh has been considered as one of the transition economies in the South Asia. Industrial sector supports second largest share to the GDP of Bangladesh. The industrial productivity in the country is solely dependent on the locally available natural gas and imported raw materials. Energy Efficiency (EE) and Cleaner Production (CP) measures in the industry can facilitate the promotion of low carbon industrial development through pollution prevention and energy conservation. The main objective of this research is to identify the policy instruments for the promotion of low carbon industrial development in Bangladesh within RECP framework. In this research, ceramics sector has been taken as a research unit. Based on the research objective, three research strategies have been followed which are: 1) review of the existing Environmental Policy, Industrial Policy and Energy Policy of Bangladesh, 2) review of the relevant measures adopted in the regional countries, and 3) case study in a ceramic industry. Stakeholder consultation has been conducted to identify appropriate policy instruments based on multi-criteria evaluation. Through this research, eleven policy instruments have been identified in connection with the promotion of RECP measures in the country with the target of developing low carbon industrial operation. Among the eleven policy instruments seven policy instruments have been identified as prioritized policy instruments based on multi-criteria evaluation through stakeholder consultation. Apart from the prioritized policy instruments the Government of Bangladesh (GoB) has to make realistic sector wise policies and specific policy targets to be achieved within timeline. The GoB has to increase
Structural and Magnetic Properties of Mn0.50-xZn0.50CuxFe2O4  [PDF]
Farhad Alam, Mohammad H. R. Khan, Hari N. Das, Akther A. K. M. Hossain
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.412106

Mn0.50-xZn0.50CuxFe2O4 (where x = 0.0 - 0.3) ferrites have been synthesized by auto combustion method. X-ray diffraction patterns reveal that all compositions are of single phase cubic spinel structure. The lattice parameter decreases with the increase in Cu2+ content obeying the Vegard’s law. The bulk density, average grain size, initial permeability, Néel temperature and saturation magnetic induction of Mn0.50-xZn0.50CuxFe2O4 increased with increasing Cu2+content. It is observed that both density and initial permeability increase with increasing sintering temperature. The maximum initial permeability is found to be 1061 which is almost four times greater than that of the parent composition. The resonance frequency of all the samples shifts towards the lower frequency as the permeability increases with Cu2+ content. It is observed from B-H loops of Mn

Magnetic Hysteresis and Complex Initial Permeability of Cr3+ Substituted Mn-Zn Ferrites  [PDF]
F. Alam, M. L. Rahman, M. H. R. Khan, A. K. M. Akther Hossain
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.514122

The impact of Cr3+ ion on the magnetic properties of Mn0.50Zn0.50CrxFe2-xO4 (with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) has been studied. Ferrite samples were synthesized by combustion method and sintered at various temperatures (1250°C, 1300°C and 1350°C). The structural properties were investigated by means of X-ray diffraction patterns and indicated that the samples possess single phase cubic spinel structure. The lattice parameter decreases with the increase in Cr3+ content, as the ionic radius of Cr3+ ion is smaller than that of Fe3+. The average grain size (D), bulk density (ρB) and initial permeability μidecreases with increase

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