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Insights into structural and spectroscopic characterization of Sm^(3+)doped orange rich red emitting CsmgPO_(4)phosphors

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Journal of Rare Earths 2022年第12期40卷 1837-1848,I0001页

作者： m.k.Pradhan S.Dash Department of Physics and Astronomy National Institute of Technology RourkelaRourkela769008OdishaIndia

In the present study,Sm^(3+)activated inorganic orthophosphate CsmgPO_(4)(CSmP)phosphors were prepared by adopting a solid-state reaction *** structural phase purity and morphological features were studied by X-ray powder diffraction(XRD)and scanning electron microscopy(SEm),*** molecular structure and vibrational modes were substantiated with the Fourier transform infrared spectroscopy(FTIR)and Raman spectroscopy *** optical bandgap of the host and Sm^(3+)doped phosphors was deduced from the diffused reflectance(DR)spectra with a typical value of 5.72 eV and a small variation is observed with increasing concentrations.A systematic study of photoluminescence(PL)properties of Sm^(3+)doped CSmP phosphors was carried *** the room temperature excitation and emission spectra,it is found that the phosphor emits in the orange rich red light under the suitable excitation of 402 nm in the UV region and concentration quenching occurs at x=0.02 doping *** emission peaks observed at around 562,598 and 644 nm confirm the characteristic Sm^(3+)4 f-4 f *** temperature-dependent photoluminescence(TD-PL)of the x=0.02(optimum doping)is recorded from 30 to 210℃,showing good thermal stability even at 150℃.The thermal quenching mechanisms are discussed based on the configuration coordinate model of excitation and *** prepared phosphors are found to exhibit near thermal stability compared to the commercially available red *** decay time and quantum efficiency were *** colour coordinates are found to lie in the orangish-red region of the colour *** the prepared phosphors CSmP:x Sm^(3+)can be useful as a red component in designing UV excitable chip-based phosphor-converted white LED applications.

关键词： Charge compensation Red phosphors Thermal stability Configuration coordinate model Luminescence Rare earths

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Generalized thermoelastic functionally graded spherically isotropic solid containing a spherical cavity under thermal shock

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Applied mathematics and mechanics(English Edition) 2008年第10期29卷 1263-1278页

作者： m.k.Ghosh m.kanoria Department of mathematics Serampore CollegeSeramporeHooghly-712201India Department of Applied mathematics University of Calcutta 92 A.P.C.RoadKolkata-700009India

This paper is concerned with the determination of thermoelastic displacement, stress and temperature in a functionally graded spherically isotropic infinite elastic medium having a spherical cavity, in the context of the linear theory of generalized thermoelasticity with two relaxation time parameters （Green and Lindsay theory）. The surface of cavity is stress-free and is subjected to a time-dependent thermal shock. The basic equations have been written in the form of a vector-matrix differential equation in the Laplace transform domain, which is then solved by an eigenvalue approach. Numerical inversion of the transforms is carried out using the Bellman method. Displacement, stress and temperature are computed and presented graphically. It is found that variation in the thermo-physical properties of a material strongly influences the response to loading. A comparative study with a corresponding homogeneous material is also made.

关键词： generalized thermoelasticity functionally graded material (FGm) Green-Lindsay theory vector-matrix differential equation Bellman method

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Displacements and stresses in composite multi-layered media due to varying temperature and concentrated load

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Applied mathematics and mechanics(English Edition) 2007年第6期28卷 811-822页

作者： m.k.Ghosh m. kanoria Department of mathematics Serampore CollegeSeramporeHooghly-712 201India Department of Applied mathematics University of Calcutta92 A. P. C. RoadKolkata-700 009India

This paper deals with the determination of the thermo-elastic displacements and stresses in a multi-layered body set up in different layers of different thickness having different elastic properties due to the application of heat and a concentrated load in the uppermost surface of the medium. Each layer is assumed to be made of homogeneous and isotropic elastic material. The relevant displacement components for each layer are taken to be axisymmetric about a line, which is perpendicular to the plane surfaces of all layers. The stress function for each layer, therefore, satisfies a single equation in absence of any body forces. The equation is then solved by integral transform technique. Analytical expressions for thermo-elastic displacements and stresses in the underlying mass and the corresponding numerical codes are constructed for any number of layers. However, the numerical comparison is made for three and four layers.

关键词： thermal stress layered body concentrated load Bessel function integral transform

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Synthesis and Properties of Ag-doped Titanium-10 wt% 45S5 Bioglass Nanostructured Scaffolds

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Acta metallurgica Sinica(English Letters) 2015年第4期28卷 467-476页

作者： k.Jurczyk.a.mik.a.zewski k.Niespodziana m.kubicka m.U.Jurczyk m.Jurczyk Department of Conservative Dentistry and Periodontology Poznan University of Medical Sciences Institute of materials Science and Engineering Poznan University of Technology Department of Genetics and Pharmaceutical microbiology Faculty of PharmacyPoznan University of Medical Sciences Division mother’s and Child’s Health Poznan University of Medical Sciences

A new kind of biomedical Ti-45S5 Bioglass-Ag nanocomposites and their scaffolds with antibacterial function was developed by the introduction of 1.5 wt% Ag into the Ti-10 wt% 45S5 Bioglass matrix. The microstructure, hardness and corrosion resistance in Ringer solution of the Ag-doped Ti-45S5 glass were investigated. The Vickers hardness of the bulk Ti-10 wt% 45S5 Bioglass-1.5 wt% Ag nanocomposites reached 480 HVo.3. Contact angles of water on the micro- crystalline Ti and nanostructured Ti-10 wt% 45S5 Bioglass-1.5 wt% Ag sample were determined and show visible decrease from 55.2° to 49.6°. In vitro tests culture of normal human osteoblast cells showed very good cells proliferation, colonization and multilayering. In vitro bacterial adhesion study indicated a significantly reduced number of bacteria （Staphylococcus aureus） on the bulk nanostructured Ti-10 wt% 45S5 Bioglass-1.5 wt% Ag plate surface in comparison with that on microcrystalline Ti plate surface. Development of porous Ti-10 wt% 45S5 Bioglass-1.5 wt% Ag scaffolds aims in enhancing bone ingrowth and prosthesis fixation.

关键词： Biomaterials Nanocrystalline materials Titanium 45S5 Bioglass

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THREE-DImENSIONAL VISUALIZATION OF DEGENERATE FERRITE FORmED BELOW TTT-DIAGRAm BAY IN AN Fe-C-mo ALLOY

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Acta metallurgica Sinica(English Letters) 2003年第3期16卷 169-174页

作者： k.m.Wu m.Enomoto Department of materials Science Ibaraki University Nakanarusawa Hitachi 316-8511 Japan

The evolution of degenerate ferrite in an Fe-0.28wt%C-3.0wt%mo alloy isothermally reacted for 10ks at 20℃ below TTT diagram bay temperature have been revealed utilizing serial sectioning in conjunction with computer reconstruction and visualization. The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary. The degenerate morphology of ferrite may be attributed to repeated nucleation, growth and coalescence of adjacent ferrite crystals. The shape of individual ferrite crystals appears to be rod-like.

关键词： steel phase transformation microstructure ferrite

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New ternary superconducting compound LaRu2As2： Physical properties from density functional theory calculations

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Chinese Physics B 2017年第3期26卷 453-460页

作者： m A Hadi m S Ali S H Naqib A k m A Islam Department of Physics University of Rajshahi Rajshahi 6205 Bangladesh Department of Physics Pabna University of Science and Technology Pabna 6600 Bangladesh International Islamic University Chittagong Chittagong 4203 Bangladesh

In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elas- tic constants ensure the mechanical stability of the compound. The calculated Cauchy pressure, Pugh＇s ratio as well as Poisson＇s ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating （TBC） material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machinable because of its low hardness value of 6.8 GPa. The multi-band nature is observed in the calculated Fermi surface. A highly anisotropic combination of ionic, covalent and metallic interactions is expected to be in accordance with charge density calculation.

关键词： new superconductor LaRu2As2 density functional theory (DFT) calculations mechanical proper-ties electronic features

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Student Behavior modeling for an E-Learning System Offering Personalized Learning Experiences

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Computer Systems Science & Engineering 2022年第3期40卷 1127-1144页

作者： k.a.hirami m.k.kavitha Devi Department of Computer Science and Engineering Kings College of EngineeringPudukkottai613303India Department of Computer Science and Engineering Thiagarajar College of EngineeringMadurai625015India

With the advent of computing and communication technologies,it has become possible for a learner to expand his or her knowledge irrespective of the place and ***-based learning promotes active and independent *** scale e-learning platforms revolutionized the concept of studying and it also paved the way for innovative and effective teaching-learning *** digital learning improves the quality of teaching and also promotes educational ***,the challenges in e-learning platforms include dissimilarities in learner’s ability and needs,lack of student motivation towards learning activities and provision for adaptive learning *** quality of learning can be enhanced by analyzing the online learner’s behavioral characteristics and their application of intelligent instructional *** is not possible to identify the difficulties faced during the process through evaluation after the completion of e-learning *** is thus essential for an e-learning system to include component offering adaptive control of learning and maintain user’s interest *** this research work.a.framework is proposed to analyze the behavior of online learners and motivate the students towards the learning process accordingly so as to increase the rate of learner’s objective *** to the demands of e-learner,an intelligent model is presented in this study for e-learning system that apply supervised machine learning *** adaptive e-learning system suits every category of learner,improves the learner’s performance and paves way for offering personalized learning experiences.

关键词： Learner behavior modeling e-learning intelligent learning system machine learning algorithm

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Unsteady natural convection Couette flow of heat generating/absorbing fluid between vertical parallel plates filled with porous material

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Applied mathematics and mechanics(English Edition) 2012年第3期33卷 303-314页

作者： B.k.JHA m.k.mUSA Department of mathematics Ahmadu Bello UniversityZaria 234Nigeria mathematics Unit School of Basic and Remedial StudiesAhmadu Bello UniversityFuntua 6007Nigeria

The extended Brink.a. Darcy model for momentum equations and an energy equation is used to calculate the unsteady natural convection Couette flow of a viscous incompressible heat generating/absorbing fluid in a vertical channel （formed by two infinite vertical and parallel plates） filled with the fluid-saturated porous medium. The flow is triggered by the asymmetric heating and the accelerated motion of one of the bounding plates. The governing equations are simplified by the reasonable dimensionless parameters and solved analytically by the Laplace transform techniques to obtain the closed form solutions of the velocity and temperature profiles. Then, the skin friction and the rate of heat transfer are consequently derived. It is noticed that, at different sections within the vertical channel, the fluid flow and the temperature profiles increase with time, which are both higher near the moving plate. In particular, increasing the gap between the plates increases the velocity and the temperature of the fluid, however, reduces the skin friction and the rate of heat transfer.

关键词： heat generating/absorbing fluid natural convection flow porous material acceleration motion

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PV based water pumping system for agricultural irrigation

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Frontiers in Energy 2016年第3期10卷 319-328页

作者： T A BINSHAD k VIJAYAkUmAR m kALEESWARI Department of Electrical Engineering Malaviya National Institute of Technology Jaipur 302017 India Department of Electrical Engineering Poomima University Jaipur302017 India

This paper investigates the operation and analysis of the photovoltaic water pumping system in detail. Power electronic controllers were designed and developed for the water pumping system using a boost converter along with an inverter followed by an induction motor pump set. The proposed system could be employed in agricultural irrigation under any operating condition of varying natures of solar irradiances and temperatures. The configuration and implementation of the system were described in detail. Further, the detailed method of analysis and simulation characteristics of such PV water pumping system was also presented. With the concern of shortage of fossil fuel, global warming and energy security, the proposed PV based water pumping significant demand of electricity agricultural sector. system can meet the and serve for the

关键词： photovoltaic water pumping system power electronic controller solar irradiances and temperature

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Insights into the physical properties and anisotropic nature of ErPdBi with an appearance of low minimum thermal conductivity

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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)

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