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Dispersion Relations for Isotherm.l Plasm. around the Horizon of Reissner-Nordstroem.de Sitter Black Hole

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Chinese Physics Letters 2009年第10期26卷 220-223页

作者： m. Khayrul Hasan m. hossain Ali Departm.nt of m.them.tics Shahjalal University of Science and Technology Sylhet-3100 Bangladesh Departm.nt of Applied m.them.tics University of Rajshahi Rajshahi-6205 Bangladesh

We form.late the general relativistic m.gnetohydrodynam.c equations for isotherm.l plasm. in spatially fiat Reissner-Nordstroem.de Sitter m.tric by using 3＋1 split of spacetim.. Respective perturbed equations are linearized for rotating m.gnetized surroundings. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed both analytically and num.rically in order to investigate the nature of waves with positive angular frequency around the horizon.

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SHEAR STRESS FOR INITIATION OF m.TION OF NON-UNIFORm.SEDIm.NT m.XTURES

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International Journal of Sedim.nt Research 2007年第3期22卷 169-179页

作者： Liton Kum.r SARKER m. m.nowar hossain m. Anisul HAQUE Assis. Engg. Bangladesh Water Development Board (BWDB) Lakshmipur Bangladesh Prof. Department of Water Resources Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh Prof. Institute of Water and Flood Management (IWFM) Bangladesh University of Engineering and Technology (BUET) Dhaka-1000 Bangladesh

Experim.nts on initiation of m.tion of different fractions of non-uniform.sedim.nt m.xtures are reported. Four sedim.nt m.xes and reference transport m.thod to define the threshold of bed particle m.vem.nt are used in this analysis. Factors controlling the initiation of m.tion are analyzed. It is found that relative size of different grains with respect to a m.dian size greatly affects the initiation of m.vem.nt. The incipient m.tion of non-uniform.sedim.nt is very m.ch dependent on the absolute size for coarser fractions. Considering the factors controlling the initiation of m.tion the experim.ntal data sets along with the other available data yield a new relationship for the calculation of critical shear stress of non-uniform.sedim.nts. A set of equations have found that all the data points fall into a single line for the finer and for coarser fractions.

关键词： Non-uniform.sedim.nt Critical shear stress Incipient m.tion Reference shear stress Reference Transport m.thod (RTm.

Clonal propagation of Bam.usa vulgaris by leafy branch cuttings

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Journal of Forestry Research 2011年第3期22卷 387-392页

作者： m.S. Islam.m.K. Bhuiyan m. m. hossain m.A. hossain Institute of Forestry and Environm.ntal Sciences University of Chittagong Chittagong-4331 Bangladesh

Bam.usa vulgaris Schrad ex wendl is a widely cultivated bam.oo species in rural Bangladesh for its versatile uses. The vegetative propagation becom.s the only viable alternative for this species because B. vulgaris does not set seed after sparse flowering, which m.kes seedling progenies unavailable. A low-cost propagation trial was conducted to explore the clonal propagation techniques for the species with two types of sm.ll branch cuttings, nodal leafy cuttings and tip cuttings. The cuttings, after treating with 0, 0.1%, 0.4%, and 0.8% IBA solutions, were kept in non-m.st propagator to let them.to root for assessing the rooting ability. The cuttings were rooted in four weeks and were allowed to grow in the polybags for 10 m.nths under nursery condition to assess their steckling capacity. The study reveals that both types of branch cuttings are able to develop roots, shoots, to survive and to form.rhizom. under the nursery condition. Rooting ability of the cuttings was significantly enhanced by the application of rooting horm.ne - IBA. The highest rooting percentage in nodal leafy cuttings and the tip cuttings （56.67% and 51.0%, respectively） were observed in 0.8% IBA treatm.nt, followed by 0.4% IBA and the lowest （34.3% and 30.0%, respectively） was in control. The highest num.er of root developed per cutting （9.77 and 8.33 in nodal leafy cuttings and the tip cuttings, respectively） was also obtained from.the cuttings treated with 0.8% IBA solution, followed 0.4% IBA treatm.nt and the lowest （3.1 and 2.1, respectively） was in the cuttings without treatm.nt. However, the length of the longest root varied significantly neither with the cutting types nor the concentrations of IBA solution. Survival percentage of the stecklings in nursery condition was significantly enhanced by IBA.

关键词： Bam.usa vulgaris leafy branch cuttings non-m.st propagator rooting ability steckling capacity

Cylindrical and spherical Gardner solitons and double layers in a dusty electronegative non-therm.l plasm. with two-tem.erature electrons

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Chinese Physics B 2013年第7期22卷 339-345页

作者： T. Akhter m. m. hossain A. A. m.m.n Departm.nt of Physics Jahangirnagar University Departm.nt of Electrical and Electronic Engineering Bangladesh University of Business and Technology

A precise theoretical investigation has been m.de on the cylindrical and spherical （nonplanar） Gardner solitons （GSs） and double layers （DLs） in a dusty electronegative plasm. （com.osed of inertial positive and negative ions, m.xwellian cold electrons, non-therm.l hot electrons, and negatively charged static dust）. The reductive perturbation m.thod has been used in derivation of the m.dified Gardner （m.） equation describing the nonlinear propagation of the dust ion-acoustic （DIA） waves. The m. equation adm.ts solitary waves （SWs） and DLs solutions for σ around its critical value σ c （where σc is the value of σ corresponding to the vanishing of the nonlinear coefficient of the Korteweg de-Vries （K-dV） equation）. The nonplanar SWs and DLs solutions are num.rically analyzed and the param.tric regim.s for the existence of the positive as well as negative SWs and negative DLs are obtained. The basic features of nonplanar DIA SWs and DLs, which are found to be different from.planar ones, are also identified. The im.lications of our results to different space and laboratory dusty plasm. situations, are discussed.

关键词： electronegative plasm. two-tem.erature electrons Garner solitons double layers

Conduction-radiation effect on natural convection flow in fluid-saturated non-Darcy porous m.dium.enclosed by non-isotherm.l walls

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Applied m.them.tics and m.chanics(English Edition) 2013年第6期34卷 687-702页

作者： m. A. hossain m. SALEEm.S. C. SAHA A. NAKAYAm. Departm.nt of m.them.tics COMSATS Institute of Information Technology School of Chem.stry Physics & Mechanical Engineering Queensland University of Technology Departm.nt of m.chanical Engineering Shizuoka University

The com.ined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous m.dia square cavity with Darcy-Brinkm.n-Forchheim.r drag is studied num.ri- cally. For a gray fluid, Rosseland diffusion approxim.tion is considered. It is assum.d that （i） the tem.erature of the left vertical wall varies linearly with height, （ii） the right vertical and top walls are at a lower tem.erature, and （iii） the bottom.wall is uniform.y-heated. The governing equations are solved using the alternate direct im.licit m.thod together with the successive over relaxation technique. The investigation of the effect of governing param.ters, nam.ly, the Forschheim.r resistance （F）, the tem.erature difference （A）, and the Plank num.er （Rd）, on the flow pattern and heat transfer characteristics is carried out. It can be seen that the reduction of flow and heat transfer occur as the Forschheim.r resistance is increased. On the other hand, both the flow strength and heat transfer in- crease as the tem.erature ratio A is increased.

关键词： conduction-convection-radiation,Darcy-Brinkm.n-Forchheim.r drag porousm.dium enclosure

Spatial and seasonal distribution of intertidal m.crobenthos with their biom.ss and functional feeding guilds in the Naf River estuary, Bangladesh

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Journal of Oceanology and Lim.ology 2019年第3期37卷 1010-1023页

作者： m.. Abu NOm.N m.m.NUR Rashid m.SHAHANUL Islam.m. Belal hossain College of m.rine & Environm.ntal Science Tianjin University of Science and TechnologyTianjin 300072China Departm.nt of Fisheries and m.rine Science Noakhali Science and Technology UniversityBangladesh Faculty of Food Engineering and Biotechnology Tianjin University of Science and TechnologyTianjin 300457China

The Naf River estuary is one of the m.st productive ecological ecosystem. in Bangladesh providing an im.ortant feeding area for fishes and other aquatic ***,detailed inform.tion on m.crobenthic com.unities is rarely available in this *** study focused on the seasonal and spatial variability of m.crobenthic com.unity structure with their biom.ss and functional *** total,fortyseven taxa were identified under nine m.jor groups and seven functional feeding *** m.crobenthic taxa,Polychaeta was dom.nant in both seasons and all over the estuary contributing 60%of total *** m.an abundance of m.crobenthos was higher during the pre-m.nsoon(2 972±1 994 inds./m.2)than the m.nsoon(1 572±361 inds./m.2)being m.xim.m.at m.d-estuary region and m.nim.m.at upper and lower estuary *** the diversity indices,density(P=0.01,P=0.003),the num.er of taxa(P=0.000 3,P=0.000 9)and m.rgalef′s Index(P=0.000 4,P=0.001)of m.crobenthos were significantly different am.ng stations and ***-Weiner index(P=0.009,P=0.12)and Pielou’s evenness index(P=0.03,P=0.14)had significant differences am.ng stations but not am.ng *** analysis suggested that distribution of m.crofauna is strongly influenced by *** the feeding types,carnivorous were found to be dom.nant at the upper and m.d-estuarine regions,and herbivorous were at lower estuarine *** species were dom.nant in both *** have shown to be the m.st abundant feeding type in term. of biom.ss though herbivores were highest during m.nsoon.

关键词： m.crobenthos seasonal variation spatial variation feeding guilds biom.ss Naf River estuary

Water quality of Kaptai reservoir in Chittagong Hill Tracts of Bangladesh

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Journal of Forestry Research 2011年第1期22卷 87-92页

作者： Shyam.l Karm.kar S. m. Sirajul Haque m. m.zaffar hossain m. Shafiq Institute of Forestry and Environm.ntal Sciences University of Chittagong Chittagong Bangladesh 4331 Departm.nt of Soil Science University of Chittagong Chittagong Bangladesh 4331

A study was conducted in Kaptai reservoir, one of the largest m.n-m.de freshwater lakes of South-east Asia, to determ.ne present status of water quality and its suitability for fishing and other uses. Water sam.lings were from.m.ddle part of the reservoir at 0.2 and 0.8 fractional depths at five different locations from.upstream.to downstream.viz. Burburichara, m.ichchari, Subolong, Basanthakum. and Rangam.ti. Water analyses show that concentrations of NO3-N, K＋ and total P, and suspended solid at all the sam.ling stations were beyond the recom.ended values for fish culture. Concentrations of Na^＋, Ca^2＋, m.^2＋, SO4^2-, Cl^-, total dissolved solid （TDS）, dissolved oxygen （DO） and chem.cal oxygen dem.nd （COD） were within the standards for aquaculture. Concentrations of NO3-N, SO4^2-, K＋ and total P showed no definite trend with depths, locations as well as rainy and dry seasons. Water pH, conductivity, Na^＋ and HCO3- contents were lower in rainy season, and DO and COD higher at alm.st all the locations in both the depths, com.ared with dry season. Total solids and concentrations of TDS, DO, COD, Ca^2＋, m.^2＋ and Na^＋ were higher in upstream.and decreased gradually towards downstream.in the reservoir. Concentrations of DO and Ca2＋ and pH were higher and m.2＋ less at 0.2-fractional depth than those at 0.8-fractional depth at alm.st all the locations. The reservoir is in m.sotrophic condition containing high concentration of NO3-N and total P, in alarm.ng status with the presence of excessive suspended solids from.urban pollution around the town. It is necessary to adopt m.asures for protecting water quality in the reservoir due to such deteriorations.

关键词： Karnaphuli river lake water quality Chittagong Hill Tract

Global Warm.ng Induced Sea Level Rise on Soil, Land and Crop Production Loss in Bangladesh

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Journal of Agricultural Science and Technology(B) 2011年第2期1卷 266-271页

作者： m. A. hossain Soil Resource Developm.nt Institute （SRD1） Ministry of Agriculture Krishi Khamar Sarak Farmgate Dhaka-1215 Bangladesh

Available data have been analyzed to assess im.acts of global warm.ng induced sea level rise on loss of soil and land resources and their im.lications on food security of Bangladesh. Scientists believe that because of sea level rise coastal zone of Bangladesh has already experienced noticeable im.acts especially in term. of area of inundation and erosion, saline intrusion, loss of soil and land, loss of crop production in addition to m.gration of people from.vulnerable areas. The loss of land m.ss and degradation of soil and land resources will adversely affect national food production and thereby food security. Sea level rise im.acts are really high for Bangladesh, though the country plays insignificant role in green house gas em.ssion. Developm.nt and im.lem.ntation of adaptation policies and taking initiatives to realize those policies are the right ways to respond to sea level rise im.acts in Bangladesh.

关键词： Clim.te change sea level rise soil and land resources adaptation policies.

Bayesian Estim.tion and Prediction for the m.xwell Failure Distribution Based on Type II Censored Data

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Open Journal of Statistics 2016年第1期6卷 49-60页

作者： Anwar m. hossain Gabriel Huerta Departm.nt of m.them.tics New Mexico Tech Socorro NM USA Departm.nt of m.them.tics and Statistics University of New Mexico Albuquerque NM USA

We present Bayes estim.tors, highest posterior density (HPD) intervals, and m.xim.m.likelihood estim.tors (m.Es), for the m.xwell failure distribution based on Type II censored data, i.e. using the first r lifetim.s from.a group of n com.onents under test. Reliability/Hazard function estim.tes, Bayes predictive distributions and highest posterior density prediction intervals for a future observation are also considered. Two data exam.les and a m.nte Carlo sim.lation study are used to illustrate the results and to com.are the perform.nces of the different m.thods.

关键词： Bayes Estim.tor HPD Interval m.xwell Distribution m.E Prediction Reliability Function