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Preparation and Magnetic Properties of Mn-Zn Ferrites by the Co-precipitation Method

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Journal of Wuhan University of Technology(Materials Science) 2009年第6期24卷 875-878页

作者：李雪张俊喜 School of Environmental and Chemical engineering Shanghai University Electrochemical Research Group Shanghai University of Electric PowerKey Laboratory of State Power Corporation of China

Mn-Zn ferrites （Mn1-xZnxFe2O4） with different compositions were prepared by the coprecipitation method, and the influences of such synthesis conditions as pH value, composition and volume ratio （R） of the mixed solution and NH4HCO3.solution on their microstructures and magnetic properties were discussed. The samples were characterized by X-ray diffraction （XRD） and magnetization measurement instrument. Lattice parameters and average crystalline size of the synthesized materials were calculated from the corresponding XRD patterns with the related software Jade.5. For samples of different pH values, only one phase was found when pH values were 7.0, 8.0 and 9.0. The sample with pH value of 7.0 exhibited the highest saturation magnetic induction, the lowest coercive force, and crystallized best. For samples of different R values with pH value of 7.0, only one phase was observed in all samples, and the sample with R value of 2.3.exhibited the highest saturation magnetic induction and the lowest coercive force. The composition has mainly afected the magnetic properties, and the saturation magnetic induction increases with the increase of the content of Zn （x）, but decreases when x is beyond 0.6. The trend of coercive force is on the contrary. However, no magnetism is exhibited when the x value is up to 0.8.

关键词： co-precipitation method microstructure magnetic property Mn-Zn ferrite

NEAR WAKE OF A MODEL HORIZONTAL-AXIS WIND TURBINE

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Journal of Hydrodynamics 2009年第2期21卷 285-291页

作者： HU Dan-mei DU Zhao-hui School of power and Enviromental engineering Shanghai University of Electric Power Shanghai 200090 China School of Mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China

An experimental investigation on the properties of the near wake behind the rotor of a Horizontal-Axis Wind Turbine （HAWT） was carried out at model scale. Measurements were made with a stationary slanted hot-wire anemometer using the technique of phase-locked averaging. The primary aim is to study the formation and development of the three-dimensional wake. Five axial locations were chosen within four chord lengths of the blades over a range of tip speed ratios. The results show that during the downstream developmerit of the wake, the wake centre traces a helical curve with its rotation direction opposite to that of the rotor. The distribution of mean velocity behind the HAWT rotor reveals an expansion and a decay of the three-dimensional wake. The shapes of the mean velocity distribution are similar along the blades span at the same downstream axial location. It is shown that the turbulence levels in the wake are higher than those in the non-wake region. The circumferential component and the radial component of the turbulence intensity are higher than the axial component. Our study offers some food of thought for better understanding of the physical features of the flow field as well as the performance of HAWT.

关键词： horizontal-axis wind turbine wake flow hot-wire anemometry experimental

Variable structure multiple model for articulated human motion tracking from monocular video sequences

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Science china(Information Sciences) 2012年第5期55卷 1138-1150页

作者： HAN Hong 1,TONG MingLei 2,CHEN ZhiChao 1 & FAN YouJian 1 1 Key Laboratory of Intelligent Perception and Image Understanding of Ministry of Education of china,Institute of Intelligent Information Processing,Xidian University,Xi'an 710071,china 2 School of Computer and Information engineering,{3. University of electric power,{3. 200090,china 1. Key Laboratory of Intelligent Perception and Image Understanding of Ministry of Education of china Institute of Intelligent Information Processing Xidian University Xi’an 710071 China2. School of Computer and Information Engineering Shanghai University of Electric Power Shanghai 200090 China

A new model-based human body tracking framework with learning-based theory is introduced in this *** propose a variable structure multiple model (VSMM) framework to address challenging problems such as uncertainty of motion styles,imprecise detection of feature points,and ambiguity of joint *** human joint points are detected automatically and the undetected points are estimated with Kalman *** motion models are learned from motion capture data using a ridge regression *** model set that covers the total motion set is designed on the basis of topological and compatibility relationships,while the VSMM algorithm is used to estimate quaternion vectors of joint *** using real image sequences and simulation videos demonstrate the high efficiency of our proposed human tracking framework.

关键词： human motion tracking ridge regression model groups design variable structure multiple model (VSMM) motion model group adaptation

THE METHOD OF SEMI-FALSE TRANSIENT FOR COMPUTING THE FLOW INTO POROUS MEDIUM IN THE CIRCULAR PIPE

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Journal of Hydrodynamics 2002年第2期14卷 91-95页

作者： Chen Jin-e department of Thermal power engineering, {3. University of electric power, shanghai 200090, china Jiang Jin-liang department of Information and Computing Science, {3. University of electric power, shanghai 200090, china department of Thermal power engineering，{3. University of electric power Shanghai 200090China department of Information and Computing Science，shanghai University of electric {3. Shanghai 200090China

The method of semi-false transient was used to numerically compute the incompressible steady flow into the porous medium in this paper. The fundamental equations were established and numerically solved in the united flow field, which included the space region and the porous region. The non-equidistant non-orthogonal semi-staggered mesh system was used in the method of semi-false transient. The computational results of two problems concerning the flow into porous medium from space region, in which there was the backward flow besides main flow, were obtained and discussed. It is seen from the results that the backward flow is generally not present in the porous medium as the osmotic resistance is very large.

关键词： porous flow incompressible flow steady flow method of semi-false transient

Preparation and Microstructure of Spinel Zinc Ferrite ZnFe_2O_4 by Co-precipitation Method

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Journal of Wuhan University of Technology(Materials Science) 2009年第6期24卷 927-930页

作者：任平 department of Energy Sources and Environment engineering Shanghai University of Electric Power

Spinel zinc ferrites ZnFe2O4, prepared by co-precipitation method using the zinc nitrate Zn（NO3.2·6H2O and ferric nitrate Fe（NO3.3.2H2O as the raw materials, were characterized by the thermo gravimetric analysis （TG） and differential scanning calorimeter （DSC）, X-ray diffraction （XRD） and scanning electron microscope （SEM）. The influence of synthesis conditions, such as Zn/Fe molar ratio, pH value, the sintering temperature and time, on the microstructures was detailedly investigated. The relationships between the microstructures and the synthesis conditions were discussed. The results show that the pure spinel zinc ferrites ZnFe2O4 are formed when the Zn/Fe molar ratio is 1.05∶2 at pH=8.5 or Zn/Fe molar ratio is 1∶2 at Ph=9-10, and the precursors are sintered at 1100 ℃ for 4 h. Especially no other phases are observed when the Zn/Fe molar ratio is 1∶2 at pH=10 and the precursor is sintered above 700 ℃ for 4 h. The higher sintering temperature and longer sintering time contribute to grain growth.

关键词： zinc ferrites ZnFe2O4 microstructures co-precipitation

Effects of Heat Treatment Temperature and Time on Structure and Static Magnetic Property of W-type Ferrite Hollow Microspheres

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Journal of Wuhan University of Technology(Materials Science) 2007年第1期22卷 168-170页

作者：任平 Energy Source and Environmental engineering department Shanghai University of Electric Power

Hollow spheres of hexagonal ferrite BaCozFelrO27 were fabricated through a spray pyrolysis technique using co-precipitation ferrite powder precursor as materials, followed by calcinations in an air atmosphere. The phase composition, micro-morphology, and static magnetic property of the particles were measured by XRD, SEM, and VSM. The results indicate that the method for preparation of ferrite hollow microspheres （FHM） results in a broad particles size distribution. The density of FHM decreased from 5.3. g/ cm^3.to 2.3. g/cm^3. When the heating rate was 5℃/min, and temperature was 1 200℃ for 4 hours, pure W-type ferrites were formed. With the heat treatment temperature and time increasing, the crystal structure becomes perfect, the saturation magnetization is increased and the coercive force is decreased.

关键词： microwave absorber ferrite hollow microspheres spray pyrolysis

A NEW DEPTH-AVERAGED TWO-EQUATION (K-) TURBULENT CLOSURE MODEL AND ITS APPLICATION TO NUMERICAL SIMULATION FOR A RIVER

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Journal of Hydrodynamics 1991年第2期3卷 21-28页

作者： Yu Li-ren, shanghai Institute of electric power, shanghai, 200090, P.R. china

The paper mainly focuses on describing the modification made to a new depth-averaged two-equation turbulent closure model based on the revised κ-ω model recently. In the case of side discharged jets with tempera- ture difference and transverse current, the new model has been investigated numerically in detail. As a practical example of application to use the new model, the side discharge of the cooling water from three outlets into a natu- ral river on one bank has been simulated, and the geomorphic variation under water has been treated suitably. Two depth-averaged models, and have been used, the later was the unique one up to the present. Emphasis is placed on the comparative research with different models under the same computational conditions. It has been verified that if the discharged flow rates are relatively small, when the pollutant plume in the near and transitional zons is predicted, the agreement with experimental and field data simulated by the model is better than by the model or other methods commonly used in engineering.

关键词： TURBULENT CLOSURE MODEL AND ITS APPLICATION TO NUMERICAL SIMULATION FOR A RIVER A NEW DEPTH-AVERAGED TWO-EQUATION ITS

Chimney Effect Assessment of the Double-skin Facade

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湖南大学学报（自然科学版） 2009年第S1期36卷 146-150页

作者： QIU Zhong-zhu1,LI Peng2,CHOW Tin-tai3.REN Jian-xing1,WANG Wen-huan1(1.School of Energy & Environment engineering,shanghai University of electric {3.,shanghai 20090,china 2.School of Mechanical engineering,Tongji University,shanghai 200092,china 3.Division of Building Science & Technology,City University of Hong Kong,Hong Kong SAR,china) School of Energy and Environment engineering Shanghai University of Electric Power Shanghai 200090 China School of Mechanical engineering Tongji University Shanghai 200092 China Division of Building Science and Technology City University of Hong Kong Hong Kong Hong Kong

The mathematic model of heat transfer through ventilated double glazing was verified with the measured data,which were from a test chamber equipped with glass face temperature,solar radiation,ambient temperature,and wind speed measurement *** the model validation,the double-skin facade assessment was carried out through simulation with ESP-r software integrating thermal simulation and air low net work *** air flow situation in the air gap was analyzed on the basis of the hourly air velocity simulation data within typical winter week,summer week,spring week and autumn *** differences of chimney effect in different seasons were discussed,and the thermal loads resulted from the ventilated and unventilated double skin facade were presented.

关键词： chimney effect assessment double-skin facade

Dielectric Properties of Capacitive-Type Humidity Sensor Made under Different Pressures

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稀有金属材料与工程 2006年第S3期 366-368页

作者： Jing Wang~1 Xiao-hua Wang~2 (1.School of Electron and Information engineering,Dalian University of Technology,Dalian 116023.china) (2.department of Computer Science and Information,{3. University of electric power,{3. 200090,china)

Capacitive humidity sensors were made of nanometer barium *** pellets were prepared under different pressures between 3.20N to 7850N *** capacitance changes in three orders of magnitude in the relative humidity range of 10%～98%,indicating high humidity sensitivity of the *** a certain measuring frequency,the capacitance of the sensors increases as increasing of the preparation pressure,while the sensitivity of the sensors basically remains the *** frequencies corresponding to the peaks of the dielectric loss of the sensors move to the higher frequency direction as increasing of the relative *** a certain humidity,the frequencies corresponding to the peaks of the dielectric loss move to the higher frequency direction as increasing of the preparation pressure.

关键词： humidity sensor capacitive-type preparation pressure humidity sensing property