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Applied Mathematics and Mechanics(English Edition) 2019年第9期40卷 1285-1300页

作者： M. MADHU n. s. sHAsHIKUMAR b. MAHAnTHEsH b. J. GIREEsHA n. KIsHAn Department of studies and Research in Mathematics Kuvempu University Shankaraghatta 577451 India Department of Mathematics Christ Deemed to be University Bangalore 560029 India Department of Mathematics Osmania University Telangana 500007 India

The entropy generation and heat transfer characteristics of magnetohydrodynamic (MHD) third-grade fluid flow through a vertical porous microchannel with a convective boundary condition are analyzed. Entropy generation due to flow of MHD non-newtonian third-grade fluid within a microchannel and temperature-dependent viscosity is studied using the entropy generation rate and Vogel's model. The equations describing flow and heat transport along with boundary conditions are first made dimensionless using proper non-dimensional transformations and then solved numerically via the finite element method (FEM). An appropriate comparison is made with the previously published results in the literature as a limiting case of the considered problem. The comparison confirms excellent agreement. The effects of the Grashof number, the Hartmann number, the biot number, the exponential space-and thermal-dependent heat source (EsHs/THs) parameters, and the viscous dissipation parameter on the temperature and velocity are studied and presented graphically. The entropy generation and the bejan number are also calculated. From the comprehensive parametric study, it is recognized that the production of entropy can be improved with convective heating and viscous dissipation aspects. It is also found that the EsHs aspect dominates the THs aspect.

关键词： microchannel entropy generation bejan number third-grade fluid magnetic field

Electrical properties of rare earth based tungsten bronze vanadates

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Journal of Rare Earths 2012年第11期30卷 1134-1137页

作者： b.b.Mohanty P.s.sahoo R.n.P.Choudhary Department of Physics Betnoti College Betnoti Department of Physics ITER

barium based tungsten bronze （Tb） oxides having high dielectric constant and low loss, can be effectively used as transducers, actuators, capacitors and also in memory devices. All these characteristics stimulated the researchers to replace toxic and hazardous lead based materials by barium based Tb materials from industry. In the present research work, polycrystalline samples of baasrRTi3VTO30 （R=Dy, sm, La） were synthesized by a high temperature solid state reaction technique. Preliminary structural （X-ray diffraction） analyses of these com- pounds showed the formation of single-phase orthorhombic structures at room temperature having average crystallite size of the order of some nanometer for all the compounds. The scanning electron micrographs （sEM） provided information on the quality of the samples and showed more or less homogeneous distribution of grains over the entire surface of the samples. Detailed dielectric study in a wide temperature range （30-500 ℃） showed ferro to para phase transition for Dy and sm substituted samples whereas no such transition was observed for La substituted samples. both the grain and grain boundary resistances exhibited negative temperature coefficient of resistance behavior much like semiconductors. The dc conductivity of all the compounds obeyed Arrhenius relation.

关键词： ceramics X-ray diffraction dielectric properties electrical conductivity rare earths

Performance analysis of silicon nanowire transistors considering effective oxide thickness of high-k gate dielectric

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Journal of semiconductors 2014年第4期35卷 48-51页

作者： s.Theodore Chandra n.b.balamurugan national Instruments Electronics Laboratory Department of ECE Thiagarajar College of Engineering

We have analyzed the effective oxide thickness （EOT） of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional si02 gate insulator with a material that has a much higher dielectric constant （high-k） gate, materials like si3n4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier （natori） approach, which is composed of several matlab scripts. Our results show that hafnium oxide （HfO2） gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of lifO2 is found to be 0.4 nm.

关键词： high-k dielectric hafnium oxide silicon nanowire transistor effective oxide thickness

superhydrophobic PVDF/TiO_2-siO_2 Membrane with Hierarchical Roughness in Membrane Distillation for Water Recovery from Phenolic Rich solution Containing surfactant

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Chinese Journal of Polymer science 2019年第6期37卷 609-616页

作者： n.Hamzah C.P.Leo b.s.Ooi school of Chemical Engineering Engineering Campus Universiti Sains Malaysia

superhydrophobic poly(vinylidene fluoride)(PVDF) membrane incorporated with nanoparticles was applied in membrane distillation to recover water from phenolic rich solution containing surfactant. The membranes coated on woven support were fabricated using phase inversion with dual bath coagulation and post-modified using silane. The membranes incorporated with TiO_2, siO_2, or a mixture of TiO_2-siO_2 nanoparticles achieved the water contact angle higher than 160°. The addition of TiO_2-siO_2 mixture into PVDF matrix further enhanced the hierarchical roughness of membrane. Hence, PVDF/TiO_2-siO_2 membrane achieved the highest permeation flux and rejected 99.9% of gallic acid in the feed(100 g/L). PVDF/TiO_2-siO_2 membrane also maintained a relative flux(J/J0) higher than0.9 after 8 h of operation. Even with the presence of surfactant in phenolic rich solution, PVDF/TiO_2-siO_2 membrane was able to exhibit relative flux above 0.8. The significant changes on the hydrophobicity and chemical properties of PVDF/TiO_2-siO_2 membrane due to fouling were not observed after 50 h of static adsorption test.

关键词： superhydrophobic PVDF nano particles Roughness Membrane distillation

secure Probabilistic Prediction of Dynamic Thermal Line Rating

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Journal of Modern Power systems and Clean Energy 2022年第2期10卷 378-387页

作者： n.safari s.M.Mazhari C.Y.Chung s.b.Ko Grid Operations support SaskPower.ReginaSKS4P 0S1Canada the Department of Electrical and Computer Engineering University of SaskatchewanSaskatoonSKS7N 5A9Canada

Accurate short-term prediction of overhead line(OHL)transmission ampacity can directly affect the efficiency of power system operation and *** overcstiniation of the dynamic thermal line rating(DTLR)can lead to the lifetime degradation and failure of OHLs,safety hazards,*** paper presents a secure yet sharp probabilistic model for the hour-ahead prediction of the *** security of the proposed DTLR limits the frequency of DTLR prediction exceeding the actual *** model is based on an augmented deep learning architecture that makes use of a wide range of predictors,including historical climatology data and latent variables obtained during DTLR ***,by introducing a customized cost function,the deep neural network is trained to consider the DTLR security based on the required probability of exceedance while minimizing the deviations of the predicted DTLRs from the actual *** proposed probabilistic DTLR is developed and verified using recorded experimental *** simulation results validate the superiority of the proposed DTLR compared with the state-of-the-art prediction models using well-known evaluation metrics.

关键词： Deep neural network dynamic thermal line rating overhead line prediction recurrent neural network

Idiosyncratic behaviour of(na_(0.49)5K_(0.455)Li_(0.05))(nb_(0.95)Ta_(0.05))O_3-La_2O_3 ceramics: synergistically improved thermal stability, ageing, and fatigue properties

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Journal of Advanced Ceramics 2019年第1期8卷 79-89页

作者： bhupender RAWAL n. n. WATHORE b.PRAVEEnKUMAR H. s. PAnDA Armament Research and Development Establishment Department of Materials Engineering Defence Institute of Advanced Technology

La_2 O_3 doped(na0.495 K0.455 Li0.05)(nb0.95 Ta0.05)O_3 ceramics are prepared using modified milling process, and the influences of La2 O3 on ferroelectric behaviour, ageing characteristics, thermal stability, electrical stability, crystal structure, microstructure, dielectric and piezoelectric properties were reported. La_2 O_3 addition improved the ferroelectric characteristic substantially, and obtained remnant polarization(Pr) and maximum strain(smax) around 34.3 C/cm^2 and 0.13% ***_2 O_3 doped ceramics improved the thermal stability and were stable up to 180 ℃ compared to undoped ceramics(120 ℃). The Rietveld refinement along with the high-temperature X-ray diffraction studies suggested the presence of monoclinic phase in La doped compositions, which is responsible for their idiosyncratic behaviour. The maximum values were obtained around 179 pC/n and 0.385 for piezoelectric constant(d33) and electromechanical coupling factor(kp) respectively in La_2 O_3 doped samples(0.02 wt%), which also exhibited the lowest ageing rate and stable electrical fatigue behaviour.

关键词： dielectric fatigue piezoelectric thermal stability

Green ionic metal-organic frameworks as nanocatalysts for CO_(2)fixation

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nano Research 2025年第1期18卷 260-269页

作者： nuria Martín Miguel Maireles-Porcar Julián sánchez Velandia belén Altava Francisco G.Cirujano Eduardo García-Verdugo Departamento de Química Inorgánica y Orgánica Universidad Jaume IAv.Sos Baynats/nCastellóde la PlanaCastellón 12071Spain

Co,ni,and Zn iso-reticular coordination polymers of 2,5-dihydroxyterphthalic acid(H_(2)dot)can be rapidly obtained under room temperature and aqueous conditions using either sodium or ammonium hydroxide as the bases to deprotonate the *** use of metal bromides and tetrabutylammonium hydroxide(TbAOH)as the base allows the green synthesis of ionic metal-organic frameworks(MOFs),characterized by X-ray diffraction(XRD),Fourier transform infrared(FTIR),scanning electron microscopy(sEM),thermo gravimetric analysis(TGA),H-nuclear magnetic resonance(nMR),elemental analysis,and X-ray photoelectron spectroscopy(XPs),and employed in the pressure,solvent,and additive-free CO_(2)fixation to epoxides by its cycloaddition to epichlorohydrin,exhibiting a cooperative behavior between the MOF and the ionic liquid formed within the framework,achieving TOns of the confined tetrabutylammonium bromide(TbAbr)up to 700.

关键词： metal-organic frameworks(MOFs) ionic liquids heterogeneous catalysis CO_(2)conversion

Positron Energy Levels in Cd-based semiconductors

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Communications in Theoretical Physics 2013年第6期59卷 756-762页

作者： b.Abbar s.Mécabih s.Amari n.benosman b.bouhafs Laboratoire de Modélisation et de simulation en sciences des Département de Physique Université Djillali Liabès

Using the full potential linearized augmented plane wave FP-LAPW method within local density ap-proximation LDA, we have studied positron diffusion and surface emission in Cd-based semiconductors. This requires the calculation of electron and positron band structures. In the absence of experimental and theoretical data for CdX (X=s,se,Te) we have treated the si, which has been studied by several authors, as a test case. Predictive results on positron effective masses, deformation potentials, positron work functions, diffusion constants and positron mobilities are presented for CdX (X=s, se, Te). Our calculated data for si are compared with experimental and recent theoretical results.

关键词： DFT FP-LAPW semiconductors positron diffusion

Direct microwave leaching conditions of rare earth elements in fluorescent wastes

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Journal of Rare Earths 2024年第6期42卷 1165-1174,I0007页

作者： A.bilen b.birol M.n.saridede s.s.Kaplan M.s.sonmez Department of Metallurgical and Materials Engineering Yildiz Technical UniversityIstanbulTurkey Department of Chemical Engineering and Materials science Stevens Institute of TechnologyNew JereyUSA Department of Metallurgical and Materials Engineering Istanbul Technical UniversityIstanbulTurkey

The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s *** can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth *** the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent *** the yields were *** the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HnO_(3)),sulphuric acid(H_(2)sO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were *** highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(s:L),and 90 *** energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction ***,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed ***,mathematical models of all experimental studies are created with the response surface box-behnken method and the correlation coefficients of all the models are over 90%.

关键词： Rare earth elements(REEs) Direct microwave leaching Fluorescent waste Kinetic models Response surface method

Development of Zeff diagnostic system on the Globus-M（M2） tokamak and the first experimental results

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Plasma science and Technology 2019年第10期21卷 33-39页

作者： E A TUKHMEnEVA s Yu TOLsTYAKOV G s KURsKIEV V K GUsEV V b MInAEV Yu V PETROV n V sAKHAROV A Yu TELnOVA n n bAKHAREV P b sHEGOLEV E O KIsELEV Ioffe Institute

studying the behavior of effective ion charge Zeff, which indicates the degree of pollution of plasma and can provide valuable information about many processes taking place in plasma, mechanisms of the releasing impurities, transport, etc is of great interest. This paper describes the development of the Zeff diagnostic system for the Globus-M2 tokamak. The effective ion charge is determined on the basis of measurements of the bremsstrahlung intensity and Thomson scattering data-Te and ne profiles. The results of the first Zeff measurements obtained for several discharges on the Globus-M tokamak are presented in this paper. The results have been validated by simulation using the AsTRA transport code for the same discharges, and it has demonstrated a good agreement with the experimental results.

关键词： tokamak effective ion charge magnetic confinement