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

作者： S K mitro R majumder K m hossain md Zahid Hasan md Emran hossain m A Hadi Bangamata Sheikh Fojilatunnesa mujib Science and Technology University Jamalpur-2012Bangladesh Physics Discipline Khulna UniversityKhulna-9208Bangladesh Department of materials Science and Engineering University of RajshahiRajshahi-6205Bangladesh Department of Electrical and Electronic Engineering International Islamic University ChittagongKumiraChittagong-4318Bangladesh Department 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 machinability. 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 minimum thermal conductivity is very low for Er Pd Bi compared to the several species. This low value of minimum thermal conductivity introduces the potentiality of Er Pd Bi in high-temperature applications such as thermal barrier *** addition, deep optical insights of Er Pd Bi reveal that our material can be used in different optoelectronic and electronic device applications ranging from organic light-emitting diodes, solar panel efficiency, waveguides etc. to integration of integrated circuits. Therefore, we believe that our results will provide a new insight into high-temperature applications and will benefit for the development of promising optoelectric devices as well.

关键词： Er Pd Bi minimum thermal conductivity anisotropy density functional theory(DFT)

magnetic, Dielectric and Complex Impedance Properties of xBa_(0.95)Sr_(0.05)TiO_3–(1-x)BiFe_(0.9)Gd_(0.1)O_3multiferroic Ceramics

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Acta metallurgica Sinica(English Letters) 2016年第6期29卷 505-517页

作者： m.J.miah A.K.m.Akther hossain Department of Physics Bangladesh University of Engineering and Technology Department of Physics Comilla University

xBa_（0.95）Sr_（0.05）TiO_3–（1-x）BiFe_（0.9）Gd_（0.1）O_3[x BST–（1-x）BFGO]（x = 0.00, 0.10, 0.20 and 0.25） multiferroic ceramics were prepared by the standard solid-state reaction technique. Structural characterization was performed by X-ray diffraction. All the samples showed rhombohedral distorted perovskite structure. Surface morphology of the ceramics was studied by the field emission scanning electron microscope（FESEm）. From the FESEm observation, the grain size was observed to be decreased with increasing BST content. Enhanced magnetic properties were observed in BFGO with the increase in BST content because of large lattice distortion. The complex initial permeability increased with the increasing of BST content. The study of dielectric properties showed that the dielectric constant increased, whereas dielectric loss decreased with increasing of BST content due to the reduction of oxygen vacancies. An analysis of the electric impedance and modulus with frequency was performed at different temperatures. Non-Debye-type relaxation processes occur in the compound which was confirmed from the nature of the Cole–Cole plot. The DC conductivity was found to increase with the rise in temperature which indicates the semiconducting behavior of the compound with characteristics of the negative temperature coefficient of resistance. The activation energy, responsible for the relaxation determined from the modulus spectra（0.246 eV）, was found to be almost same as the value obtained from the impedance study（0.240 eV）, indicating that charge carriers overcome the same energy barrier during relaxation. The frequency response of imaginary parts of electric impedance and modulus suggested that the relaxation in xB ST–（1-x）BFGO ceramics follows the same mechanism at various temperatures.

关键词： magnetic properties Dielectric properties Impedance spectroscopy Activation energy

Dispersion Relations for Isothermal Plasma 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 Department of mathematics Shahjalal University of Science and Technology Sylhet-3100 Bangladesh Department of Applied mathematics University of Rajshahi Rajshahi-6205 Bangladesh

We formulate the general relativistic magnetohydrodynamic equations for isothermal plasma in spatially fiat Reissner-Nordstroem-de Sitter metric by using 3＋1 split of spacetime. Respective perturbed equations are linearized for rotating magnetized surroundings. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed both analytically and numerically in order to investigate the nature of waves with positive angular frequency around the horizon.

关键词： No English Keyword

Structural,Dielectric and Complex Impedance Spectroscopy Studies of Lead Free Ca_(0.5+x)Nd_(0.5-x)(Ti_(0.5)Fe_(0.5))O_3

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Journal of materials Science & Technology 2013年第4期29卷 323-329页

作者： m.R.Shah A.K.m.Akther hossain Department of Physics University of PrimeasiaBananiDhaka 1213Bangladesh Department of Physics Bangladesh University of Engineering and TechnologyDhaka 1000Bangladesh

Structural and various electrical properties of polycrystalline Ca0.5＋xNd0,5-x（Ti0.5Fe0.5）O3, prepared by standard solid state reaction technique, were studied. Formation of single phase orthorhombic structure of the compositions was confirmed by X-ray diffraction study. The composition dependence of lattice parameters, density and microstructural study show that they vary significantly with Ca content. The dielectric measurements were carried out at room temperature as function of frequency and composition. The experimental results reveal that the dielectric constant （ε′） increases with increasing Ca content. Similar behavior is observed for the dielectric loss （tanδ） and ac conductivity （σac）. In complex impedance analysis it is observed that the real part （Z′） vs imaginary part （Z″） graph exhibits a tendency of formation of a single semicircular arc for each composition of samples. Different parameters were determined by fitting the experimental data in Cole-Cole empirical formula. A dominance of grain boundary resistance （Rgb） is observed. The Rgb decreases with increasing Ca content. The high ε′ observed in present samples are suitable for fabrication of devices.

关键词： Crystal structure Dielectric properties Lead free Perovskite Solid state reaction

Conduction-radiation effect on transient natural convection with thermophoresis

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Applied mathematics and mechanics(English Edition) 2012年第3期33卷 271-288页

作者： S.m.mAHFOOZ m.A.hossain Department of mathematics COMSATS Institute of Information TechnologyPark RoadChak ShahzadIslamabad 44000Pakistan

This paper discusses the effect of thermophoretic particle deposition on the transient natural convection laminar flow along a vertical fiat surface, which is immersed in an optically dense gray fluid in the presence of thermal radiation. In the analysis, the radiative heat flux term is expressed by adopting the Rosseland diffusion approximation. The governing equations are reduced to a set of parabolic partial differential equations. Then, these equations are solved numerically with a finite-difference scheme in the entire time regime. The asymptotic solutions are also obtained for sufficiently small and large time. The obtained asymptotic solutions are then compared with the numerical solutions, and they are found in excellent agreement. moreover, the effects of different physical pa- rameters, i.e., the thermal radiation parameter, the surface temperature parameter, and the thermophoretic parameter, on the transient surface shear stress, the rate of surface heat transfer, and the rate of species concentration, as well as the transient velocity, temperature, and concentration profiles are shown graphically for a fluid （i.e., air） with the Prandtl number of 0.7 at 20℃ and 1.013 × 10^5 Pa.

关键词： radiation optically dense fluid transient natural convection thermophorestic particle deposition

Comparison of Propofol and Fentanyl for Preventing Emergence Agitation Following Sevoflurane Anesthesia in Pediatric Patients: A Single-Center Study in Bangladesh

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Pharmacology & Pharmacy 2024年第6期15卷 223-235页

作者： md. Saiful Islam Khan md. Abir Tazim Chowdhury Farzana Fardousi munama magdum md. Ahaduzzaman Taneem mohammad Shamima Akter Suriya Akter md. Saiful Islam Azad md. mozaffer hossain m. Abdur Rahman Department of Cardiothoracic Anesthesia Evercare Hospital Dhaka Bangladesh Department of Cardiothoracic and Vascular Surgery Evercare Hospital Dhaka Bangladesh Department of Pathology National Institute of Cancer Research & Hospital Dhaka Bangladesh Department of Preventive and Social medicine National Institute of Preventive and Social Medicine Dhaka Bangladesh Department of Anesthesia Sheikh Sayera Khatun Medical College Gopalgonj Bangladesh Department of Anesthesia Dhaka Medical College Dhaka Bangladesh Department of Anesthesia Combined Military Hospital Dhaka Bangladesh Department of Cardiac Anesthesia National Institute of Cardiovascular Disease Dhaka Bangladesh Department of Anesthesia Bangladesh Medical College Dhaka Bangladesh

Background: Emergence agitation (EA) is a common phenomenon observed in pediatric patients following general anesthesia. This study aimed to assess the efficacy of propofol and fentanyl in preventing EA and to compare their associated complications or side effects. methods: This prospective randomized observational comparative study was conducted at Dhaka medical College Hospital from July 2013 to June 2014. The study aimed to evaluate the effects of propofol and fentanyl on EA in children aged 18 to 72 months undergoing circumcision, herniotomy, and polypectomy operations. Ninety children were included in the study, with 45 in each group. Patients with psychological or neurological disorders were excluded. Various parameters including age, sex, weight, American Society of Anesthesiologists (ASA) class, duration of anesthesia, Saturation of Peripheral Oxygen (SPO2), heart rate (HR), respiratory rate (RR), Pediatric Anesthesia Emergence Delirium (PAED) score, duration of post-anesthesia care unit (PACU) stay, incidence of laryngospasm, nausea, vomiting, and rescue drug requirement were compared between the two groups. Results: Age, sex, weight, ASA class, and duration of anesthesia were comparable between the two groups. Perioperative SpO2 and HR were similar in both groups. However, the PAED score was significantly higher in the fentanyl group during all follow-ups except at 30 minutes postoperatively. The mean duration of PACU stay was significantly longer in the fentanyl group. Although the incidence of laryngospasm was higher in the fentanyl group, it was not statistically significant. Conversely, nausea or vomiting was significantly higher in the fentanyl group. The requirement for rescue drugs was significantly higher in the fentanyl group compared to the propofol group. Conclusion: Both propofol and fentanyl were effective in preventing emergence agitation in pediatric patients undergoing various surgical procedures under sevoflurane anesthesia. However, propo

关键词： Emergence Agitation (EA) General Anesthesia Propofol Fentanyl Pediatric Patients Pediatric Anesthesia Emergence Delirium (PAED) Score Bangladesh

Interactions of ion acoustic multi-soliton and rogue wave with Bohm quantum potential in degenerate plasma

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Chinese Physics B 2017年第9期26卷 301-309页

作者： m S Alam m G Hafez m R Talukder m hossain Ali Department of Applied mathematics University of RajshahiRajshahi-6205Bangladesh Plasma Science and Technology Lab Department of Applied Physics and Electronic EngineeringUniversity of RajshahiRajshahi-6205Bangladesh Department of mathematics Chittagong University of Engineering and TechnologyChittagong-4349Bangladesh

This work investigates the interactions among solitons and their consequences in the production of rogue waves in an unmagnetized plasmas composing non-relativistic as well as relativistic degenerate electrons and positrons, and inertial non-relativistic helium ions. The extended Poincare′–Lighthill–Kuo（PLK） method is employed to derive the two-sided Korteweg–de Vries（KdV） equations with their corresponding phase shifts. The nonlinear Schrodinger equation（NLSE） is obtained from the modified Kd V（mKdV） equation, which allows one to study the properties of the rogue waves. It is found that the Fermi temperature and quantum mechanical effects become pronounced due to the quantum diffraction of electrons and positrons in the plasmas. The densities and temperatures of the helium ions, degenerate electrons and positrons, and quantum parameters strongly modify the electrostatic ion acoustic resonances and their corresponding phase shifts due to the interactions among solitons and produce rogue waves in the plasma.

关键词： wave-wave interaction rogue waves degenerate plasmas Bohm potential

Distributed DC-Bus Signaling Control of Photovoltaic Systems in Islanded DC microgrid

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1741-1750页

作者： Noushin Poursafar m.J.hossain Seyedfoad Taghizadeh macquarie University SydneyNew South WalesAustralia

The stability of an islanded DC microgrid(DCmG)is highly dependent on the presence and performance of the backup energy storage system(BESS),due to the lack of main grid *** condition makes the DCmG vulnerable to the critical situation of absence of the BESS,which could be caused by a fault or being fully charged or *** paper presents an enhanced distributed DC-bus signaling control strategy for converters of photovoltaic systems(PVs)to make the islanded DCmG less dependent on the *** a conventional control approach that utilizes PVs to operate in maximum power point tracking(mPPT)mode and the BESS solely regulating DC-bus voltage,the proposed control method maintains DC-bus voltage via intelligently managing output powers of the *** proposed control method continuously monitors DC-bus voltage and regulates the output powers of all the PVs via switching between mPPT mode and voltage regulating ***,if the DC-bus voltage level is less than a predefined maximum level,the PVs work in mPPT mode;otherwise,the PVs work in voltage regulating mode to maintain DC-bus voltage at an acceptable *** switching between mPPT and voltage regulating control operations results in protecting the DCmG from unavoidable shutdowns conventionally necessary during the absence of the BESS ***,the proposed control method reduces oscillations on the DC-bus voltage during existence of the *** performance and effectiveness of the proposed control strategy are validated through different case studies in mATLAB/Simulink.

关键词： DC microgrid voltage stability islanding mode distributed control distributed generator(DG)

Influence of Lanthanum on the microstructural and Dielectric Properties of Polycrystalline Ba(Ti0.5Fe0.5)O3

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Chinese Physics Letters 2012年第4期29卷 213-216页

作者： m.R.Shah A.K.m.Akther hossain Department of Physics Primeasia UniversityBananiDhaka-1213Bangladesh Department of Physics Bangladesh University of Engineering and TechnologyDhaka-1000Bangladesh

Various polycrystalline Ba1-x Lax (Ti0.5 Fe0.5 )O3 are prepared by using the standard solid state reaction *** shaped samples prepared from each composition are sintered at 1200℃ for 5 h.X-ray diffraction patterns of these compositions confirm the formation of a single phase perovskite *** lattice parameters are decreased but the average grain size increases with the increase of La *** dielectric constant,dielectric loss and ac conductivity are studied as a function of frequency for various compositions,and their behaviors are explained on the basis of the maxwell-Wagner model A three-times enhancement of the dielectric constant is observed with the increase of La content.

关键词： Ti structure technique

Ion acoustic shock and periodic waves through Burgers equation in weakly and highly relativistic plasmas with nonextensivity

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Plasma 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 Department of of Applied mathematics University of Rajshahi Rajshahi-6205 Bangladesh Department of mathematics Chittagong University of Engineering and Technology Chittagong-4349Bangladesh Plasma Science and Technology Lab Department of Applied Physics and Electronic EngineeringUniversity of Rajshahi Rajshahi-6205 Bangladesh

A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and *** Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation *** integration of the Burgers equation is performed by the（G￠/G）-expansion *** effects of positron concentration,ion–electron temperature ratio,electron–positron temperature ratio,ion viscosity coefficient,relativistic streaming 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 plasmas ion acoustic shock and periodic waves weakly and highly relativistic effects Burgers equation