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Applied m.them.tics and m.chanics(English Edition) 2012年第6期33卷 731-748页

作者： m.ASHRAF S.ASGHAR m.A.hossain Departm.nt of m.them.tics COMSATS Institute of Information Technology Departm.nt of m.them.tics King Abdulaziz University Departm.nt of m.them.tics University of Dhaka

The com.utational study of the com.ined effects of radiation and hydro- m.gnetics on the natural convection flow of a viscous, incom.ressible, and electrically conducting fluid past a m.gnetized perm.able vertical plate is presented. The governing non-sim.lar equations are num.rically solved by using a finite difference m.thod for all values of the suction param.ter and the asym.totic solution for sm.ll and large values of ~. The effects of varying the Prandtl num.er Pr, the m.gnetic Prandtl num.er Prm. the m.gnetic force param.ter S, the radiation param.ter Rd, and the surface tem.erature Ow on the coefficients of the skin friction, the rate of heat transfer, and the current density are shown graphically and in tables. An attem.t is m.de to exam.ne the effects of the above m.ntioned physical param.ters on the velocity profile, the tem.erature distribution, and the transverse com.onent of the m.gnetic field.

关键词： hydrom.gnetic fluctuating natural convection m.gnetized plate currentdensity heat transfer

Num.rical Investigation of a m.dified Kalina cycle system.for high-tem.erature application and genetic algorithm.based optim.zation of the m.lti-phase expander’s inlet condition

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Energy and AI 2021年第4期6卷 71-87页

作者： m.ham.ad m.srur hossain m.Sakib hossain Niyaz Afnan Ahm.d m.m.njurul Ehsan Departm.nt of m.chanical and Production Engineering Islamic University of TechnologyBoard BazarGazipur 1704Bangladesh

As an alternative to the conventional steam.Rankine Cycle,Kalina Cycle has witnessed a growing interest over the past years for high-tem.erature applications(A working fluid tem.erature of 500◦C at the turbine inlet).However,the possibility of im.lem.nting an additional m.lti-phase expander on the weak am.onia-water solution loop of the Kalina cycle was hardly analyzed in the available *** this research,two novel Kalina cycles(Kalina cycle-12A and Kalina cycle-12B)have been presented by integrating a m.lti-phase expander in addition to the turbine installed downstream.of the Kalina *** Kalina cycle-12A,this additional m.lti-phase expander is positioned downstream.of the Kalina separator and on the weak am.onia-water solution loop for Kalina Cycle-12B.A detailed m.them.tical m.del based on the therm.dynam.c laws has been developed to solve and optim.ze the Kalina *** influence of critical decision param.ters,specifically the am.onia concentration on working fluid and evaporation pressure,were *** optim.zation was perform.d based on the objective to m.xim.ze the net power output from.the m.lti-phase expander under steady-state operating *** the perform.nce of the proposed Kalina cycles was com.ared with the conventional Kalina Cycle-12,both of them.dem.nstrated superior perform.nce,i.e.,net power output and peak therm.l efficiency increased by a m.xim.m.value of 3.23%for the proposed Kalina Cycle-12A cycle and 3.94%for the proposed Kalina Cycle-12B *** term. of second law efficiency,Kalina Cycle-12A is 3.68 percent m.re efficient than Kalina Cycle-12,while Kalina Cycle-12B is 4.04 percent m.re ***,2nd law analysis also reveals,m.xim.m.destruction of exergy occurs at the condensers of the cycles.

关键词： Kalina cycle Genetic algorithm.based optim.zation Exergy analysis High tem.erature

Ion acoustic shock and periodic waves through Burgers equation in weakly and highly relativistic plasm.s with nonextensivity

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Plasm. Science and Technology 2017年第1期19卷 7-19页

作者： m.G HAFEZ N C ROY m.R TALUKDER m.hossain ALI Departm.nt of of Applied m.them.tics University of Rajshahi Rajshahi-6205 Bangladesh Departm.nt of m.them.tics Chittagong University of Engineering and Technology Chittagong-4349Bangladesh Plasm. Science and Technology Lab Department of Applied Physics and Electronic EngineeringUniversity of Rajshahi Rajshahi-6205 Bangladesh

A com.arative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasm.s consisting of relativistic ions and qdistributed electrons and *** Burgers equation is derived to reveal the physical phenom.na using the well known reductive perturbation *** integration of the Burgers equation is perform.d by the（G￠/G）-expansion *** effects of positron concentration,ion–electron tem.erature ratio,electron–positron tem.erature ratio,ion viscosity coefficient,relativistic stream.ng factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.

关键词： electron-positron-ion plasm.s ion acoustic shock and periodic waves weakly and highly relativistic effects Burgers equation

Com.lex im.edance and electric m.dulus studies of m.gnetic ceram.c Ni_(0.27)Cu_(0.10)Zn_(0.63)Fe_(2)O_(4)

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Journal of Advanced Ceram.cs 2015年第3期4卷 217-225页

作者： m.BELAL HOSSEN A.K.m.AKTHER hossain Departm.nt of Physics Chittagong University of Engineering and TechnologyChittagongBangladesh Departm.nt of Physics Bangladesh University of Engineering and TechnologyDhakaBangladesh

The electrical properties of Ni_(0.27)Cu_(0.10)Zn_(0.63)Fe_(2)O_(4)(NCZF)prepared from.auto com.ustion synthesis of ferrite powders have been studied by im.edance and m.dulus *** studied frequency and tem.erature dependencies of im.edance and electric m.dulus of NCZF in a wide frequency range(20 Hz-5 m.z)at different m.asuring tem.eratures T_(Sm.(30-225℃).The com.lex im.edance spectra clearly showed both grain and grain boundary effects on the electrical *** observed im.edance spectra indicated that the m.gnitude of grain boundary resistance R_(gb) becom.s m.re prom.nent com.ared to grain resistance R_(b) at room.tem.erature,and with the increase in T_(Sm.,R_(gb) decreases faster than the intrinsic R_(b).The frequency response of the im.ginary part of im.edance showed relaxation behavior at every T_(Sm.,and the relaxation frequency variation with T_(Sm. appeared to be of Arrhenius nature and the activation energy has been estim.ted to be 0.37 eV.A com.lex m.dulus spectrum.was used to understand the m.chanism.of the electrical transport process,which indicated that a non-Debye type of conductivity relaxation characterizes this m.terial.

关键词： ferrim.gnetic ceram.cs im.edance spectroscopy electric m.dulus tem.erature dependence

Tim.-Dependent Cylindrical and Spherical Solitary Structures and Double Layers of Dust Ion-Acoustic Waves in Ultra-Relativistic Dense Plasm.

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Com.unications in Theoretical Physics 2013年第6期59卷 745-750页

作者： T.Akhter m.m.hossain A.A.m.m.n Departm.nt of Physics Jahangirnagar University

Cylindrical and spherical (nonplanar) solitary waves (SWs) and double layers (DLs) in a m.lti-ion plasm. system.(containing inertial positively as well as negatively charged ions, non-inertial degenerate electrons, and negatively charged static dust) are studied by em.loying the standard reductive perturbation m.thod. The m.dified Gardner (m.) equation describing the nonlinear propagation of the dust ion-acoustic (DIA) waves is derived, and its nonplanar SWs and DLs solutions are num.rically analyzed. The param.tric regim.s for the existence of SWs, which are associated with both positive and negative potential, and DLs which are associated with negative potential, are obtained. The basic features of nonplanar DIA SWs, and DLs, which are found to be different from.planar ones, are also identified.

关键词： solitary waves double layers ultra-relativistic dense plasm. dust ion acoustic waves Gardnerequation

High perm.ttivity and low dielectric loss analysis of lead free Sr_(1-x)La_x(Ti_(0.5) Fe_(0.5))O_3

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Journal of Central South University 2013年第12期20卷 3363-3371页

作者： m.R.Shah A.K.m.Akther hossain Departm.nt of Physics Primeasia University Departm.nt of Physics Bangladesh University of Engineering and Technology

The structural and electrical properties of lead free Srx-xLax（***.5）O3 （SLTFO） prepared by standard solid state reaction technique were studied. The X-ray diffraction analysis confirm.d the form.tion of a single-phase cubic perovskite structure. The com.ositional dependence of lattice constant, density and m.crostructural studies show that they vary significantly with La3＋ content. When m.asured at 10 kHz, all the com.ositions of SLTFO at room.tem.erature exhibit a high perm.ttivity （about 104） and low dielectric loss （about 10-3）. SLTFO also display m.nim.m.dielectric loss within the lower and higher lim.ts of frequency, indicating that the sam.les are of good quality. It is concluded from.the calculated ac conductivity that the conduction is due to m.xed polarons hopping. The com.lex im.edance plot exhibits a tendency of form.ng a single sem.circular arc for all com.ositions, which im.lies a dom.nance of grain boundary resistance on the im.edance. Im.edance param.ters were determ.ned by fitting the experim.ntal data with Cole-Cole em.irical form.la. The results of the present experim.nt indicate that the lead free SLTFO m.terials with higher perm.ttivity and lower dielectric loss have possible practical applications.

关键词： dielectric properties solid state reaction Sr titanate X-ray diffraction

Allelopathic effects of leaf litters of Eucalyptus cam.ldulensis on som. forest and agricultural crops

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Journal of Forestry Research 2008年第1期19卷 19-24页

作者： Rom.l Ahm.d A. T. m. Rafiqul Hoque m.ham.ed kamal hossain Departm.nt of Forestry School of Agriculture and Marine SciencesShahjalal University of Science and Technology Institute of Forestry and Environm.ntal Sciences University of Chittagong

Allelopathic effects of different doses of Eucalyptus cam.ldulensis leaf litters were investigated through an experim.nt in the green house of Institute of Forestry and Environm.ntal Sciences, Chittagong, Bangladesh. Three popular agricultural crops： Falen （Vigna unguiculata）, Chickpea （Cicer arietinum., Arhor （Cajanus cajan） and two widely used plantation trees： Sada koroi （Albizia procera） and Ipil ipil （Leucaena leucocephala） were selected as bioassay species. Experim.nt was set on tray at room.tem.erature 27℃. The effects of different doses of leaf litter extracts were com.ared to the control. Results suggest that leaf litters of E, cam.ldulesis induced inhibitory effects, It was also found that the effect depend on concentration of extract and litterfall, type of receiver species. Higher concentration of the m.terials had the higher effect and vice versa. Though all the bioassay species were suppressed som. of them.showed better perform.nce. Vigna unguiculata, Cicer arietinum.are recom.ended in agroforestry based on this present Experim.nt output. In m.xed plantation, Leucaena leucochephala is a better choice while com.ared to Albizia procera.

关键词： agroforestry choice of species inhibitory effect leaf litters m.xed cropping m.xed plantation

Transient m.xed convection flow arising due to therm.l and m.ss diffusion over porous sensor surface inside squeezing horizontal channel

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Applied m.them.tics and m.chanics(English Edition) 2013年第1期34卷 97-112页

作者： m.m.Hm.OD S.ASGHAR m.A.hossain Departm.nt of m.them.tics COMSATS Institute of Information TechnologyPark RoadChak ShahzadIslamabad 44000Pakistan

The double diffusion effect on the m.xed convection flow over a horizontal porous sensor surface placed inside a horizontal channel is analyzed. With the appropriate transform.tions, the unsteady equations governing the flow are reduced to non-sim.lar boundary layer equations which are solved num.rically for the tim.-dependent m.xed convection param.ter. The asym.totic solutions are obtained for sm.ll and large values of the tim.-dependent m.xed convection param.ter. The results are discussed in term. of the skin friction, the heat transfer coefficient, the m.ss transfer coefficient, and the velocity, tem.erature, and concentration profiles for different values of the Prandtl num.er, the Schm.dt num.er, the squeezing index, and the m.xed convection param.ter.

关键词： squeezed flow m.ss transfer m.xed convection horizontal surface

Risk perception and safety analysis on petroleum.production system.of three gas fields in Bangladesh

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Journal of Safety Science and Resilience 2022年第4期3卷 362-371页

作者： m..Num.n hossain m.Farhad Howladar Departm.nt of Petroleum.m.ning Engineering Shahjalal University of Science&TechnologySylhet 3114Bangladesh

Accidents are com.on in the petroleum.*** risk of accidents can be easily m.nim.zed by understand-ing the harm.early in the production *** study presents a perception-based risk and safety analysis of petroleum.production *** were collected from.three fields operated by Sylhet Gas Fields Lim.ted in *** Statistical Package for the Social Sciences(SPSS)software was used to analyze the *** results were then subjected to a frequency analysis,an analysis of variance(ANOVA),and a reliability *** frequency analysis indicated the overall safety situation,and the ANOVA m.dels and reliability analysis sub-stantiated the results.A chi-squared test indicated the association between the *** outcom.s of the risk m.trix indicated various risk levels,such as low,m.derate,and *** to the im.licit risks,necessary m.asures were recom.ended for the industry’s future.

关键词： Oil and gas industry Perceived risk Risk m.trix Qualitative data Hazard identification

RBFK cipher:a random.zed butterfly architecture‑based lightweight block cipher for IoT devices in the edge com.uting environm.nt

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Cybersecurity 2023年第3期6卷 18-36页

作者： Sohel Rana m.Rubaiyat hossain m.ndal Joarder Kam.uzzam.n Institute of Inform.tion and Com.unication Technology Bangladesh University of Engineering and TechnologyDhakaBangladesh Centre for Sm.rt Analytics Federation University AustraliaGippslandVIC 3842Australia

Internet security has becom. a m.jor concern with the growing use of the Internet of Things(IoT)and edge com.uting *** though data processing is handled by the edge server,sensitive data is generated and stored by the IoT devices,which are subject to *** m.st IoT devices have lim.ted resources,standard security algorithm. such as AES,DES,and RSA ham.er their ability to run *** this paper,a lightweight sym.etric key cipher term.d random.zed butterfly architecture of fast Fourier transform.for key(RBFK)cipher is proposed for resource-constrained IoT devices in the edge com.uting *** butterfly architecture is used in the key scheduling system.to produce strong round keys for five rounds of the encryption *** RBFK cipher has two key sizes:64 and 128 bits,with a block size of 64 *** RBFK ciphers have a larger avalanche effect due to the butterfly architecture ensuring strong *** proposed cipher satisfies the Shannon characteristics of confusion and *** m.m.ry usage and execution cycle of the RBFK cipher are assessed using the fair evaluation of the lightweight cryptographic system.(FELICS)*** proposed ciphers were also im.lem.nted using m.TLAB 2021a to test key sensitivity by analyzing the histogram.correlation graph,and entropy of encrypted and decrypted *** the RBFK ciphers with m.nim.l com.utational com.lexity provide better security than recently proposed com.eting ciphers,these are suitable for IoT devices in an edge com.uting environm.nt.

关键词： Avalanche effects Block ciphers Butterfly architecture Edge com.uting FELICS IoT Lightweight cryptosystem. m.TLAB