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Com.arative regeneration status in a natural forest and enrichm.nt plantations of Chittagong (south) forest division, Bangladesh

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Journal of Forestry Research 2004年第4期15卷 255-260页

作者： m. kamal hossain m. Lutfor Rahm.n A. T. m. Rafiqul Hoque m. Khairul Alam Institute of Forestry and Environm.ntal Sciences University of Chittagong Chittagong-4331 Bangladesh Institute of Forestry and Environmental Sciences University of Chittagong Chittagong-4331 Bangladesh Institute of Forestry and Environmental Sciences University of Chittagong Chittagong-4331 Bangladesh Forest Botany Division Bangladesh Forest Research Institute Chittagong Bangladesh

The natural regeneration of the tree species in pure natural forest stand and enrichm.nt plantations of Baraitali Forest of Chittagong (South) Forest Division, Bangladesh was studied by stratified random.quadrat m.thod during April 2002 to Novem.er 2002. Totally 100 plots of 3 m.X 3 m.in size represents a total of 64 regenerating tree species from.natural forest with an average seedlings of 24767/hm., while only 40 regenerating tree species were recorded from.enrichm.nt plan-tations with an average seedlings of 18633/hm.. m.xim.m.regeneration in natural forest was found with Castanopsis spp. (2200 seedlings/hm.) followed by Glochidion lanceolarium.(2183 /hm.) whereas, in enrichm.nt plantations m.xim.m.regen-eration was found with Dipterocarpus gracilis (2117/hm.) followed by Anogeissus acum.nata (2000/hm.). For natural forest, highest relative density was found for Castanopsis spp (8.88%), relative frequency for Glochidion lanceolarium.(7.36%), rela-tive abundance for Syzygium.spp. (3.79%) and Im.ortance Value Index were recorded with Glochidion lanceolarium.(18.24%). The corresponding values for enrichm.nt plantations were highest with Dipterocarpus gracilis (11.36%), Glochidion lanceo-larium.(9.71%), Dipterocarpus gracilis (5.92%), Glochidion lanceolarium.(23.32%) respectively. Stem.per hectare of som. com.on trees with their seedlings and saplings in both the natural stands and enrichm.nt plantations showed that only Dip-terocarpus gracilis successfully recruited in both sites but recruitm.nt was higher in natural forest. Like m.ny other prim.ry rain forests, the Baraitoli forest typically has both substantial seedlings and soil seed bank from.which regeneration m.y occur. The naturally regenerated seedlings are quite dense but it could not reach the pole stage due to hum.n interference.

关键词： Regeneration Natural forest Enrichm.nt plantations Relative density Frequency Abundance Im.ortance Value Index

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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.

关键词： Plasm. physics Gravitation and cosm.logy Astrophysics and astroparticles

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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.

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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

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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

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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

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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

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Com.arative study of m.2Ga2C with superconducting m.X phase m.2GaC： First-principles calculations

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Chinese Physics B 2017年第3期26卷 297-302页

作者： m.A Ali m.R Khatun NJahan m.m.hossain Departm.nt of Physics Chittagong University of Engineering and Technology Chittagong 4349 Bangladesh Departm.nt of Physics University of Rajshahi Rajshahi 6205 Bangladesh

The structural, electronic, optical and therm.dynam.c properties of m.2Ga2C are investigated using density func- tional theory （DFT） within the generalized gradient approxim.tion （GGA）. The optim.zed crystal structure is obtained and the lattice param.ters are com.ared with available experim.ntal data. The electronic density of states （DOS） is calculated and analyzed. The m.tallic behavior for the com.ound is confirm.d and the value of DOS at Ferm. level is 4.2 states per unit cell per eV. Technologically im.ortant optical param.ters （e.g., dielectric function, refractive index, absorption coefficient, photo conductivity, reflectivity, and loss function） are calculated for the first tim.. The study of dielectric constant （ε1） indicates the Drude-like behavior. The absorption and conductivity spectra suggest that the com.ound is m.tallic. The reflectance spectrum.shows that this com.ound has the potential to be used as a solar reflector. The therm.dynam.c properties such as the tem.erature and pressure dependent bulk m.dulus, Debye tem.erature, specific heats, and therm.l expansion coefficient of m.2Ga2C m.X phase are derived from.the quasi-harm.nic Debye m.del with phononic effect also for the first tim.. Analysis of Tc expression using available param.ter values （DOS, Debye tem.erature, atom.c m.ss, etc.） suggests that the com.ound is less likely to be superconductor.

关键词： first-principles calculations density of states (DOS) optical properties therm.dynam.c properties

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Insights into the physical properties and anisotropic nature of ErPdBi with an appearance of low m.nim.m.therm.l conductivity

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Chinese Physics B 2021年第1期30卷 398-406页

作者： S K m.tro R m.jum.er K m.hossain m. Zahid Hasan m. Em.an hossain m.A Hadi Bangam.ta Sheikh Fojilatunnesa m.jib Science and Technology University Jamalpur-2012Bangladesh Physics Discipline Khulna UniversityKhulna-9208Bangladesh Departm.nt of m.terials Science and Engineering University of RajshahiRajshahi-6205Bangladesh Departm.nt of Electrical and Electronic Engineering International Islamic University ChittagongKumiraChittagong-4318Bangladesh Departm.nt of Physics University of RajshahiRajshahi6205Bangladesh

We theoretically study the structural, elastic and optical properties of Er Pd Bi together with its anisotropic behaviors using density functional theory. It is observed that Er Pd Bi satisfies the Born stability criteria nicely and possesses high quality of m.chinability. The anisotropic behavior of Er Pd Bi is reported with the help of theoretical anisotropy indices incorporating 3 D graphical presentation, which suggests that Er Pd Bi is highly anisotropic in nature. It is noticed that the m.nim.m.therm.l conductivity is very low for Er Pd Bi com.ared to the several species. This low value of m.nim.m.therm.l conductivity introduces the potentiality of Er Pd Bi in high-tem.erature applications such as therm.l barrier *** addition, deep optical insights of Er Pd Bi reveal that our m.terial can be used in different optoelectronic and electronic device applications ranging from.organic light-em.tting diodes, solar panel efficiency, waveguides etc. to integration of integrated circuits. Therefore, we believe that our results will provide a new insight into high-tem.erature applications and will benefit for the developm.nt of prom.sing optoelectric devices as well.

关键词： Er Pd Bi m.nim.m.therm.l conductivity anisotropy density functional theory(DFT)

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Non-Newtonian effect on natural convection flow over cylinder of elliptic cross section

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Applied m.them.tics and m.chanics(English Edition) 2020年第2期41卷 361-382页

作者： P.NAG m.m.m.LLA m.A.hossain Departm.nt of m.them.tics and Physics North South UniversityDhaka 1229Bangladesh Center for Applied Scientific Com.uting(CASC) North South UniversityDhaka 1229Bangladesh Departm.nt of m.them.tics University of DhakaDhaka 1000Bangladesh

The non-Newtonian effect in the boundary layer flow over a horizontal elliptical cylinder is investigated num.rically. A m.dified power-law viscosity m.del is used to correlate the non-Newtonian characteristics of the fluid flow. For natural convectionflows, the surface of the cylinder is m.intained by the uniform.surface tem.erature(UST)or the uniform.heat flux(UHF) condition. The governing equations corresponding to theflow are first transform.d into a dim.nsionless non-sim.lar form.using suitable transform.tions. The resulting equations are solved num.rically by an efficient finite difference schem.. The num.rical results are presented for the skin friction coefficient and the local Nusselt num.er with the eccentric angle for different values of the power-law index n. The local skin friction coefficient and the local Nusselt num.er are found to be higher and lower, respectively, for the shear thickening fluids(n > 1) than the other fluids(n≤1).The effects of different elliptical configurations on the average Nusselt num.er are also presented and discussed for both conditions of the surface tem.erature.

关键词： non-Newtonian fluid free convection boundary layer elliptical cylinder

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