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Investigation of structural,magnetic and optical properties of rare earth substituted bismuth ferrite

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Journal of Rare Earths 2013年第4期31卷 370-375页

作者： t.Durga Rao t.Karthik Saket Asthana Advanced Functional Materials Laboratory Department of PhysicsIndian Institute of Technology Hyderabad Department of Materials Science and Engineering Indian Institute of Technology Hyderabad

Polycrystalline BiFeO3 and rare earth substituted ***3 （BRFO, R=Y, Ho and Er） compounds were prepared by rapid solid state sintering technique. Structural phase analysis indicated that all the compounds stabilized in rhombohedral structure （R3c space group） and a small orthorhombic phase fraction was observed in BRFO compounds. From the Raman spectra results, the changes in the phonon frequencies （A1） and line widths suggested lattice distortion in the BRFO compounds as was evidenced in the XRD analysis. Compared to the linear variation of magnetization with magnetic field （M-H） shown by BFO, an obvious M-H loop was observed in BRFO compounds which could be due to the suppression of space modulated spin structure and was explained on the basis of weak ferromagnetism and field induced spin reorientation. UV-Vis spectroscopy evidenced a change in local FeO6 envi- ronment due to shift in the 6Alg→4t2g energy transition band. BRFO compounds with improved remnant magnetization and coercive field are applicable for magnetoelectric devices.

关键词： structural distortion spin-reorientation G-type antiferromagnet rare earths

the tendency toward Higher Integration of *** Problems for Copper Based Lead Frame Materials

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功能材料 1993年第2期24卷 100-105页

作者： t Sakamoto Japan Electronic Materials Society Japan 本刊通讯编委

the inereasing market needs forthe VLSI(Very Large Scale IntegratedCircuit)can be classified as follows:(1)Higher packaging dellsity(2)More advanced and multifarious

关键词： the tendency toward Higher Integration of I.C.and Problems for Copper Based Lead Frame Materials 功能材料

Performance and Internal Flow of Sirocco Fan Using Contra-Rotating Rotors

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Journal of thermal Science 2008年第1期17卷 35-41页

作者： J.Fukutomi t.Shigemitsu t.Yasunobu Institute of Science and technology The University of Tokushima2-1 Minamijyosanjima-choTokushima 770-8506JAPAN Institute of Science and technology The University of Tokushima2-1 Minamijyosanjima-choTokushima 770-8506JAPAN Research Associate Graduate School of Advanced technology and Science The University of Tokushima2-1 Minamijyosanjima-choTokushima 770-8506JAPAN

A sirocco fan using contra-rotating rotors in which an inner rotor is settled inside the sirocco fan rotor and each rotor rotates in an opposite direction was proposed for the purpose of getting the higher pressure and making the structure of a sirocco fan more compact. If the high discharge pressure is obtained with the adoption of the contra-rotating rotors, it could be used for various purposes. Pressure coefficient of a sirocco fan with contra-rotating rotors is 2.5 times as high as the conventional sirocco fan and the maximum efficiency point of contra-rotating rotors shifts to larger flow rate than a conventional sirocco fan. On the other hand, it was clarified from the flow measurement results that circumferential velocity component at the outlet of the outer rotor of contra-rotating ro- tors becomes larger than a conventional one. In the present paper, the performance of a conventional sirocco fan and a sirocco fan with contra-rotating rotors are shown and the internal flow field at the outlet of outer rotor of both cases is clarified. then, the effect of different kind of contra-rotating rotors on the performance and internal flow field is investigated and the rotor design with higher performance would be discussed.

关键词： Sirocco fan High pressure Contra-rotating rotors Slow angle Circular arc blade Aerofoil blade

A kinetic model for a single step biodiesel production from a high free fatty acid (FFA) biodiesel feedstock over a solid heteropolyacid catalyst

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Green Energy & Environment 2019年第3期4卷 328-341页

作者： Aashish Gaurav Stéphane Dumas Chau t.Q.Mai Flora t.t.Ng Department of Chemical Engineering University of Waterloo

Production of biodiesel from yellow grease(waste cooking oil and waste animal fats) is fast emerging as a promising alternative to address the twin challenges before the biodiesel industry today-fluctuation in prices of vegetable oil and the food versus fuel debate. Yellow grease has a high percentage of free fatty acids(FFA) and proves to be an unsuitable feedstock for biodiesel production from commercially viable alkalicatalyzed production systems due to saponification problems.'Green' methodologies based on heterogeneous solid acid catalyzed reactions have the potential to simultaneously promote esterification and transesterification reactions of yellow grease to produce biodiesel without soap formation and offer easy catalyst separation without generation of toxic streams. this paper presents kinetic studies for the conversion of model yellow grease feeds to biodiesel using a heteropolyacid supported on alumina(HSiW/Al2O3) using a batch autoclave. three model yellow grease feeds were prepared using canola oil with added FFA such as palmitic, oleic and linoleic acid. A pseudo homogeneous kinetic model for the parallel esterification and transesterification was developed. the rate constants and activation parameters for esterification and transesterification reactions for the model yellow grease feeds were determined. the rate constants for esterification are higher than the transesterification rate constants. the kinetic model was validated using the experimental biodiesel data obtained from processing a commercial yellow grease feed. the kinetic model could be used to design novel processes to convert various low-value waste oils, fats and non-food grade oils to sustainable biodiesel.

关键词： Yellow grease Canola oil Free fatty acids Heteropolyacid Kinetics for esterification and transesterification

Breather solutions of modified Benjamin-Bona-Mahony equation

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Chinese Physics B 2021年第2期30卷 220-226页

作者： G t Adamashvili technical University of Georgia Kostava Street 77Tbilisi0179Georgia

New two-component vector breather solution of the modified Benjamin-Bona-Mahony(MBBM)equation is *** the generalized perturbation reduction method,the MBBM equation is reduced to the coupled nonlinear Schr¨odinger equations for auxiliary *** analytical expressions for the profile and parameters of the vector breather oscillating with the sum and difference of the frequencies and wavenumbers are *** two-component vector breather and single-component scalar breather of the MBBM equation is compared.

关键词： modified Benjamin-Bona-Mahony equation generalized perturbation reduction method vector breather nonlinear waves

Real-time per-pixel focusing method for light field rendering

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Computational Visual Media 2021年第3期7卷 319-333页

作者： t.Chlubna t.Milet P.Zemcík Faculty of Information technology Brno University of Technology61200 BrnoCzech Republic

Light field rendering is an image-based rendering method that does not use 3 D models but only images of the scene as input to render new *** field approximation,represented as a set of images,suffers from so-called refocusing artifacts due to different depth values of the pixels in the *** information about depths in the scene,proper focusing of the light field scene is limited to a single focusing *** correct focusing method is addressed in this work and a real-time solution is proposed for focusing of light field scenes,based on statistical analysis of the pixel values contributing to the final *** existing techniques,this method does not need precomputed or acquired depth *** requirements and streaming bandwidth are reduced and real-time rendering is possible even for high resolution light field data,yielding visually satisfactory *** evaluation of the proposed method,implemented on a GPU,is presented in this paper.

关键词： image-based rendering light field plenoptic function computational photography

Prediction model for the diffusion length in silicon-based solar cells

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Journal of Semiconductors 2009年第7期30卷 3-6页

作者： Cheknane A Benouaz t Laboratoire d'Etude et Dveloppement des Matriaux Semiconducteurs et Dilectrques Universit Amar Telidji de Laghouat Laboratoire de Modlisation UniversitAbou BakarBelkaid de Tlemcen Algrie

A novel approach to compute diffusion lengths in solar cells is presented. thus, a simulation is done; it aims to give computational support to the general development of a neural networks （NNs）, which is a very powerful predictive modelling technique used to predict the diffusion length in mono-crystalline silicon solar cells. Furthermore, the computation of the diffusion length and the comparison with measurement data, using the infrared injection method, are presented and discussed.

关键词： diffusion length minority-cartier lifetime infrared injection solar cell prediction modelling

Review of Sodic Soil Reclamation with a Snapshot of Current Research Activity

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Chinese Geographical Science 2022年第6期32卷 1099-1109页

作者： tÓtH tibor Institute for Soil Sciences Centre for Agricultural ResearchBudapest 1022Hungary

For centuries, reclamation of sodic soils has been an essential part of cropping practices in several parts of the world. Parallel to increasing population, the need for new cropland constantly re-evaluates land suitability concepts. therefore, the importance of sodic soils as potential croplands is increasing worldwide. Although theoretically farmers can choose from a wide variety of reclamation options, according to profitability, business plans, and human and financial resources, in practice, few reclamation methods are applied at large scale. this article touches on the early history, 20th Century intensive research, and current trends of sodic soil reclamation. New approaches such as leaching, chemical amendments, addition of organic material, and biological and microbial improvements are discussed, and also brand-new approaches are reviewed. the early history is reviewed using historical books, the achievements of the last hundred years using basic technical literature, mostly books, and the current approaches of our time with fresh publications, mostly papers and two very recent conferences published in English.

关键词： gypsuming liming chemical reclamation new technology sodic soil

the Effect of Intraband transitions on the Optical Spectra of Metallic Carbon Nanotubes

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Chinese Physics Letters 2013年第7期30卷 172-175页

作者： t.Movlarooy Department of Physics University of ShahroodShahroodIran

First-principles calculations of the electronic structure and linear optical properties of metallic carbon nanotubes are carried out using the full-potential linear-augmented plane-wave *** effect of intraband transition and electric-field polarization on the optical spectra of(5,2)chiral,(15,0)zigzag,and(8,8)armchair metallic carbon nanotubes are *** optical spectra are calculated for both electric-field polarizations,parallel and perpendicular to the axis of the *** is revealed that the optical spectra are anisotropic along these two *** the parallel polarization to the tube axis,adding the intraband transition contributions shows that the dielectric function has singularity at zero frequency due to the screening effect in metallic carbon nanotubes.

关键词： polarization metallic band