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Multiphase fluid dynamics and transport processes of low capillary number cavitating flows

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Acta Mechanica Sinica 2009年第2期25卷 161-172页

作者： Xiangbin Li Guoyu Wang Zhiyi yu Wei Shyy Department of Thermal Energy Engineering Beijing Institute of Technology 100081 Beijing China Department of Nuclear Science and Engineering North China Electric Power University 102206 Beijing China Department of Aerospace Engineering University of MichiganAnn Arbor MI 48109 USA

To better understand the multiphase fluid dynamics and associated transport processes of cavitating flows at the capillary number of 0.74 and 0.54, and to validate the numerical results, a combined computational and experimental investigation of flows around a hydrofoil is studied based on flow visualizations and time-resolved interface movement. The computational model is based on a modified RNG k-ε model as turbulence closure, along with a vapor-liquid mass transfer model for treating the cavitation process. Overall, favorable agreement between the numerical and experimental results is observed. It is shown that the cavi- tation structure depends on the interaction of the water-vapor mixture and the vapor among the whole cavitation stage, the interface between the vapor and the two-phase mixture exhibits substantial unsteadiness. And, the adverse motion of the interface relates to pressure and velocity fluctuations inside the cavity. In particular, the velocity in the vapor region is lower than that in the two-phase region.

关键词： Low capillary number cavitation Multiphasedynamics Flow visualization Turbulent cavitationmodeling

Biodegradable Materials for Bone Repairs:A Review

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Journal of Materials Science & Technology 2013年第6期29卷 503-513页

作者： Lili Tan Xiaoming yu Peng Wan Ke Yang Institute of Metal Research Chinese Academy of Sciences72 Wenhua Road

With attractive research and development of biomaterials, more and more opportunities have been brought to the treatments of human tissue repairs. The implant is usually no need to exist in the body accompanied with the recovery or regeneration of the tissue lesions, and the long-term effect of exotic substance to human body should be reduced as lower as possible. For this purpose, biodegradable materials, including polymers, magnesium alloys and ceramics, have attracted much attention for medical applications due to their biodegradable characters in body environment. This paper in turn introduces these three different types of widely studied biodegradable materials as well as their advantages as implants in applications for bone repairs. Relevant history and research progresses are summarized.

关键词： Biomaterial Biodegradable Polymer Magnesium Ceramie Bone repair

Mechanism Analysis of Additional Damping Control Strategies for the High-frequency Resonance of MMC Connected to AC Grid

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CSEE Journal of Power and Energy Systems 2023年第3期9卷 1173-1181页

作者： Yanqi Hou Chongru Liu yu Wang Wei Kong State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China State Grid Economic and Technological Research Institute Co.Ltd. Beijing 102209China State Grid Corporation of China Beijing 100031China

High-frequency resonance can occur when a modular multilevel converter(MMC)is inserted into an AC *** damping control is a relatively low-cost resonance suppression strategy compared to passive damping *** paper analyzes the influences of a feed-forward voltage filter and feedback current filter for the inner controller for the high-frequency impedance characteristics of the MMC based on a ***,the mechanism,influencing factors,and limitations of the existing strategy including an additional lowpass filter in the voltage feed-forward stage are ***,a resonance suppression strategy for the inclusion of additional cascaded notch filters in the voltage feed-forward stage is proposed,and its parameter design method and applicable scenarios are *** addition,this paper analyzes the effects of the inclusion of an additional control in other stages for the inner controller of the ***,the correctness of the theoretical analysis and the proposed strategy is verified based on the simulation of an actual project on PSCAD/EMTDC.

关键词： Additional damping control strategy additional cascaded notch filters additional low-pass filter modular multilevel converter(MMC) high-frequency resonance

Fabrication of AlN-TiC/Al composites by gas injection processing

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Rare Metals 2006年第6期25卷 659-664页

作者： yu Huashun CHEN Hongmei MA Rendian MIN Guanghui The Key Laboratory of Liquid Structure and Heredity of Materials Ministry of Education Shandong University Jinan 250061 China

The fabrication of AlN-TiC/Al composites by carbon- and nitrogen-containing gas injection into Al-Mg-Ti melts was studied. It was shown that AlN and TiC particles could be formed by the in situ reaction of mixture gas （N2 ＋ C2H2 ＋ NH3） with Al-Mg-Ti melts. The condition for the formation of AlN was that the treatment temperature must be higher than 1373 K, and the amounts of AlN and TiC increased with the increase of the treatment temperature and the gas injection time It was considered that AlN was formed by the direct reaction of Al with nitrogen-containing gas at the interface of the gas bubble and the melt. However, the mechanism of TiC formation is a combination mechanism of solution-precipitation and solid-liquid reaction.

关键词： in situ composites gas injection aluminum nitride titanium carbide

Refinement and migrating behaviors in Al-Si hypereutectic alloys solidified under electromagnetic vibration

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Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 301-308页

作者： Jianbo yu Zhongming REN Kan9 DENG Shanghai Enhanced Laboratory of Ferro-Metallurgy Shanghai University Shanghai 200072 China

The effects of electromagnetic vibration （EMV） on the refinement and migration of primary silicons in the A1-18 wt pct Si alloy were investigated systematically. It was found that EMV could effectively refine primary silicons. The equivalent diameter of primary silicon first decreases slowly with the current increasing from 1 A to 3 A, but then drops rapidly between 3 A and 10 A, next gradually decreases with increasing current intensity. When the EMV intensity was low, the primary silicons were agglomerated and expelled to the top of a sample, the segregation of silicon grains gradually decreased and the agglomerating phenomena disappeared with the increase of EMV intensity, and the star-like coarse primary silicons turned refined flake or square morphology. The refinement and migration of primary silicons depended on the Lorentz force, gravity and the effective viscous force.

关键词： High magnetic field Electromagnetic vibration HypereutecticAl-Si alloys Primary silicon Refinement Migrating

Preparation,Characterization and Comparative NH_3-sensing Characteristic Studies of PANI/inorganic Oxides Nanocomposite Thin Films

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Journal of Materials Science & Technology 2010年第7期26卷 605-613页

作者： Hulling Tai Yadong Jiang Cuangzhong Xie Junsheng yu State Key Laboratory of-Electronic Thin Films and-Integrated Devices School of Optoelectronic Information University of Electronic Science and Technology of China (UESTC) Chengdu 610054 China

Polyaniline （PANI）, polyaniline/titanium dioxide （PANI/TiO2）, polyaniline/tin oxide （PANI/SnO2） and polyaniline/indium oxide （PANI/In203） thin films were developed by using an in-situ self-assembly method at -10℃. Chemical structure, optical property and morphology of all the thin films were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FTIR） spectroscopy, UV-Vis absorption spectroscopy, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. NH3 gas-sensing properties of PANI and PANI nanocomposite thin films were examined at ambient temperature. The results showed that all the sensors composed of PANI nanocomposite thin films had faster response/recovery rate with better reproducibility, selectivity and long-term stability to NH3 than PANI,thiS film sensor, and PANI/TiO2 nanocomposite thin film sensor showed optimum NH3 gas-sensing characteristics. The effect of humidity on the responses of all the sensors was also investigated.

关键词： PANI/TiO2 PANI/SnO2 , PANI/In2O3 Thin films NH3

FOURIER-CHEBYSHEV PSEUDOSPECTRAL METHOD FOR THREE-DIMENSIONAL VORTICITY EQUATION

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Journal of Computational Mathematics 1998年第5期16卷 417-436页

作者： Li, Jian Guo, Ben-yu Cao, Wei-ming Chinese Acad Sci ICMSEC State Key Lab Sci & Engn Comp Beijing 100080 Peoples R China Shanghai Univ Dept Math Shanghai 201800 Peoples R China

In this paper, a Fourier-Chebyshev pseudospectral scheme with mixed filtering is proposed for three-dimensional vorticity equation. The generalized stability and convergence are proved. The numerical results show the ... 详细信息

关键词： Pseudospectral method vorticity equation error estimates

Corrosion Resistance Mechanism of MgO-CaO Refractories to Refining Slag

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China's Refractories 2014年第2期23卷 35-38页

作者： yu Yanping yu Yanwen Zhangjiang Mechanical and Electrical School Banshan Iron & Steel Co. Ltd

Corrosion resistance and penetration resistance of MgO-CaO materials with different CaO contents （22%, 42%, 49%, 53%, in mass）to refining AOD slag or VOD slag were investigated using static crucible technique by visual observation, SEM and XRD. The corrosion resistance and penetration resistance of speci-mens decrease with the increase of CaO content. This may be caused by the formation of C3S and C2S during the reactions between specimens and the slag. The formed C3S and C2S can restrain the further penetration to the matrix. The higher the CaO content, the more the C2S or C3S formed, the lower the porosity of the speci-mens, and the lower the penetration depth and corrosion rate. The corrosion resistance to AOD slag is better than that to VOD slag, because the reaction between AOD slag and the matrix is slighter than that between VOD slag and the matrix.

关键词： corrosion resistance mechanism magne-sia -calcia refractory refining slag

A SSR Linkage Map of Maizex Teosinte F_2 Population and Analysis of Segregation Distortion

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Agricultural Sciences in China 2011年第2期10卷 166-174页

作者： ZHOU Jun-qing GUO yu-qiu GAO yu-feng LI Jian-sheng YAN Jian-bing National Maize Improvement Center of China China Agricultural UniversityBeijing 00P.R.China International Maize and Wheat Improvement Center（CIMMYT） Mexico D.F.06600Mexico

In this study,a linkage genetic map was constructed using a F2 population derived from a cross between a elite maize inbred,B73,and its progenitor,Teosinte（*** ***）,through 205 simple sequence repeat（SSR） markers and one morphological *** Mapmaker 3.0,polymorphic markers were clustered into 10 groups,covering 10 chromosomes of maizexteosinte,with a total length of 2 002.4 cM and an average interval of 9.7 *** errors were detected using R/QTL（LOD=2.0） in 109 markers referring to 176 individuals,distributed across all 10 chromosomes with a ratio 1.2%.Projected error loci were re-run and 304 out of the 460 were confirmed as errors and replaced.A new linkage map was constructed,in which markers maintained the same order but the total map length decreased to 1 947.8 cM,with an average interval of 9.4 cM between *** total,25.2%（P0.05） markers were identified to have segregation distortion,in which 34.6% deviated towards the pollination parent（B73）,30.8% deviated towards Teosinte,32.7% deviated towards heterozygote and 1.9% deviated towards both *** map was also compared with published maizexteosinte and maize IBM map.

关键词： maize molecular linkage map segregation distortion simple sequence repeat teosinte