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Numerical studies on swirling of internal fire whirls with experimental justifications

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Building Simulation 2021年第5期14卷 1499-1509页

作者： Zheming gao S.S.Li y.gao H.y.Hung Wan-ki Chow Midea Residential Air Conditioner Division FoshanGuangdongChina College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbinHeilongjiangChina Department of Building Services Engineering The Hong Kong Polytechnic UniversityHunghomKowloonHong KongChina

Numerical studies on internal fire whirls(IFW)generated in a vertical shaft model with a single corner gap were reported in this *** generation of IFW,burning rate of fuel and temperature were studied experimentally *** simulations on medium-scale IFW were carried out using a fully-coupled large eddy simulation incorporating subgrid scale turbulence and a fire source with heat release rates compiled from experimental *** transient flame shape was studied and then simulated numerically by using *** dynamic phenomena of generation and development of IFW were simulated and then compared with experimental *** predicted results were validated by comparing with experimental data,which demonstrated that an IFW can be simulated by Computational Fluid *** results for flame surface,temperature,and flame length agreed well with the experimental *** IFW flame region and intermittent region were longer than those for an ordinary pool *** modified empirical formula for centerline temperature was *** of vertical and tangential velocity in axial and radial directions were also *** vortex core radius was found to be determined by the fuel bed *** field was not measured extensively due to resources *** measured temperature distribution with predictions is acceptable because temperature is related to the heat release rate,air flow and pressure gradient.

关键词： internal fire whirl large eddy simulation vertical structure flame surface

The improvement of an object-oriented classification using multi-temporal MODIS EVI satellite data

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International Journal of Digital Earth 2009年第3期2卷 219-236页

作者： y.gao J.-F.Mas A.Navarrete Centro de Investigaciones en Ecosistemas-Universidad Nacional Autonoma de Mexico(UNAM) Antigua Carretera a Pa tzcuaro No.8701Col.Ex Hacienda de San Jose de la Huerta C.P.58190 MoreliaMichoacanMexico Centro de Investigaciones en Geografıa Ambiental-Universidad Nacional Autonoma de Mexico(UNAM) Antigua Carretera a Pa tzcuaro No.8701Col.Ex Hacienda de San Jose de la Huerta C.P.58190 MoreliaMichoacanMexico

This paper investigates the contribution of multi-temporal enhanced vegetation index(EVI)data to the improvement of object-based classification accuracy using multi-spectral moderate resolution imaging spectral-radiometer(MODIS)*** object-oriented classification,similar pixels are firstly grouped together and then classified;the produced result does not suffer the speckled appearance and closer to human *** data are from the MODIS sensor aboard Terra spacecraft.69 EVI data(scenes)were collected during the period of three years(20012003)in a mountainous vegetated *** data sets were used to study the phenology of the land cover *** land cover types show distinct fluctuations over time in EVI values and this information might be used to improve object-oriented land cover *** experiments were carried out:one was only with single date MODIS multispectral data,and the other one including also the 69 EVI *** classes were distinguished:temperate forest,tropical dry forest,grassland,irrigated agriculture,rain-fed agriculture,orchards,lava flows and human *** two classifications were evaluated with independent verification data,and the results showed that with multitemporal EVI data,the classification accuracy was improved 5.2%.Evaluated by McNemar’s test,this improved was significant,with significance level p=0.01.

关键词： enhanced vegetation index(EVI) moderate resolution imaging spectral-radiometer(MODIS) phenology object-based image classification

MAGNETORESISTANCE EFFECT OBSERVED IN Fe/Mo MULTILAyERS PREPARED By ELECTRON BEAM EVAPORATION

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Acta Metallurgica Sinica(English Letters) 2003年第3期16卷 237-240页

作者： T.He B.Zhao y.gao F.Zeng F.Pan Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua UniversityBeijing 100084 China

The Fe/Mo multilayers were prepared by electron beam evaporation, the micro structure and magnetic properties of the multilayers were studied by X-ray diffraction, vibrating-sample magnetometer (VSM) et al. The experimental results revealed that the Fe/Mo multilayers in our experimental conditions behaved magnetoresistance effect with a sharp peak on magnetoresistance (MR) ratio curve, and magnetoresistance is easily saturated at low applied magnetic fields. For [Fe(1.5nm)/Mo(1.0nm)]4,2 multilayers, MR ratio could arrive to 0.1%. The antiferromagnetic interlayer coupling could be observed in some films at room temperature. The strength of the antiferromagnetic interlayer coupling J in the films is low because of the low saturation field Hs. The relationship between magnetic properties and micro structure was also discussed in this paper.

关键词： magnetoresistance multilayer antiferromagnetic interlayer coupling nonmagnetic scattering

Development of dipole magnet power supply for BEPC-II energy upgrading project

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Radiation Detection Technology and Methods 2019年第2期3卷 32-36页

作者： X.L.Guo B.Chen C.Han y.gao University of Chinese Academy of Sciences Beijing 100049China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Dongguan Neutron Science Center Dongguan 523803China

Purpose In order to make BEPC-II to run at a higher energy,the Institute of High Energy Physics undertook an upgrading *** of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies;therefore,these four magnet power supplies are developed for the BEPC-II *** The power supplies adopt topologies of thyristor rectifiers to realize a high-power *** the control unit of each power supply,a digital current closed loop is adopted,and the key components in the feedback loop are thermostatically *** order to improve the performances of the power supplies,analog voltage regulators are added to the inner control *** These four power supplies have been tested and have already been officially used in BEPC-II,and their powers have reached the requirements of the *** test results of the current stability are described and shown in this paper,which testifies that the stabilities meet the design *** A digital control is applied to each SCR rectifier *** performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops,which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.

关键词： SCR rectifier Dipole magnet power supply Stability BEPC-II

Spray granulation of Fe and C nanoparticles and their impedance match for microwave absorption

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Journal of Materials Science & Technology 2018年第3期34卷 496-502页

作者： H.Huang y.gao C.F.Fang A.M.Wu X.L.Dong B.S.Kim J.H.Byun G.F.Zhang D.y.Zhou Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Composites Research Division Korea Institute of Materials Science797 Changwon-daeroSeongsan-guChangwonGyeongnam642-831Republic of Korea

The microwave absorbents of Fe and C nanoparticles as magnetic loss and dielectric loss material respectively were composited with the polyvinyl alcohol （PVA） as binder by spray granulation method, The electromagnetic parameters of Fe and C composite particles were analyzed by vector network. The complex permittivity and magnetic permeability of Fe and C composite particles matched well with increasing C nanoparticle content, and then the microwave loss property was improved. A minimum reflection loss （RL） of -42.7 dB at 3.68 GHz for a composite with 4.6 mm in thickness can be obtained when the content ratio of the C nanoparticles, the modified Fe nanoparticles and the PVA is 21：49：30 （Sample 3）.

关键词： Dielectric loss Magnetic loss Spray granulation method Impedance match

A MULTI-CENTER MATCHING STUDy ON THE STATUS OF MENTAL HEALTH OF LEPROSy AFFECTED PERSONS IN COMMUNITIES OF ZHEJIANG

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A MULTI-CENTER MATCHING STUDY ON THE STATUS OF MENTAL HEALTH...

Studying the fine microstructure of the passive film on nanocrystalline 304 stainless steel by EIS,XPS and AFM

2013年全国麻风皮肤性病学术年会

作者： A.Zhou W.Jingquan y.gao Health Bureau of Haining Zhejiang Skin Disease Prevention and Treatment Center Zhejiang Shangyu Skin Disease Prevention and Treatment Hospital

＜正＞Introduction:Zhejiang is located in the coastal southeast of China, with an area of 101,800 square kilometers and a population of 54,426,900. There are 16,471 leprosy registered cases by the end of 2012, among which there are 6400patients alive. Recently leprosy is on a low rate in this area and about 30 new cases are detected every year. In order to

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Studying the fine microstructure of the passive film on nano...

VALENCE CONTRAST STUDIES ON MIXED-VALENCE INORGANIC AND METALO-ORGANIC SOLIDS

2014年全国腐蚀电化学及测试方法学术交流会

作者： Z.J.Zheng y.gao y.Gui M.Zhu School of Materials Science and Engineering South China University of Technology School of Mechanical and Automotive Engineering South China University of Technology

The fine microstructure of the passive films on nanocrystalline(NC)and coarse crystalline(CC)304 stainless steels(SSs)in 0.5 M HSO were investigated by electrochemical impedance spectroscopy(EIS),X-ray photoelectron spectroscopy(XPS)and atomic force microscopy(AFM).The results indicate that the passive film on both CC and NC SSs exhibits a two-layer microstructure consisting of a compact inner layer and a porous

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VALENCE CONTRAST STUDIES ON MIXED-VALENCE INORGANIC AND META...

CALCULATION OF THE EXCHANGE INTERACTION CONSTANT BETWEEN RARE-EARTH AND TRANSITION METAL SUBLATTICESIN R_2Fe_(17_x)Al_x(R=Tb, Gd AND Dy)COMPOUNDS

Sixteenth Congress of the International Union of Crystallography

作者： P.Coppens y.gao M.R.Pressprich A.Frost-Jensen Chemistry Department State University of New York at BuffaloBuffaloNY 14214 SUNy X3 beamline at Brookhaven National Laboratory UptonNY 11973USA

＜正＞Since the position of the absorption edge differs for atoms of the same element in different chemical environments,resonance scattering can be used to study valency and the effect of site coordination on the electron-binding *** valence-specific diffraction combines crystallography with spectroscopy and gives unique,site-specific,information on electronic *** have applied valence-contrast diffraction at seven different wavelengths to single crystals of the mixed valence low-dimensional conducting

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Acta Metallurgica Sinica(English Letters) 2002年第4期15卷 401-404页

作者： y.M.Hao,C.X.Cui,y.gao,W.P.Zhao and J.S.MengDepartment of Physics, Tianjin Normal University, Tianjin 300074, China School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China Manuscript received 11 September 2001 in Department of Physics Tianjin Normal University Tianjin 300074 China School of Materials Science and Engineering Hebei University of Technology Tianjin 300130 China

An approximate calculation of the exchange interaction constant J_(RT)between the rare-earth sublattice and the transition metal sublattice in R_2Fe_(17-x)Al_x (R= Tb,Gd, and Dy) compounds is given by the molecular-field model and the results of neutron *** calculated values, -J_(R,T)/k, for Dy_2Fe_(17-x)Al_x (x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7,Gd_2Fe_(17-x)Al_x (x=7, 8) compounds are 8.62K, 8.64K, 9.52K, 10.34K and 10.66K, 10.65K, and 9.85K,respectively, they are in agreement with the experimental values, -J_(R,T)/k, of Dy_2Fe_(17-x)Al_x(x=5, 6, 7 and 8), Tb_2Fe_(10)Al_7 and Gd_2Fe_(17-x)Al_x (x=7, 8) compounds, which are 8.77K, 9.25K,10.1K, 10.9K and 10.35K, 10.1K, and 10.3K, respectively. The origins of the difference between thecalculated and the experimental results are discussed.

关键词： neutron diffraction magnetic coupling constant molecular-field model two-sublattice model