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In Vivo Corrosion Resistance of Ca-P Coating on AZ60 Magnesium Alloy

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Journal of Bionic Engineering 2013年第2期10卷 156-161页

作者： Xing Xiao Haiying yu Qingsan Zhu Guangyu Li Yang qu Rui Gu First Hospital of Jilin University Changchun 130021 P. R. China Shandong Qianfoshan Hospital Jinan 250014 P. R. China Shandong Tumour Hospital Jinan 250117 P. R. China College of Materials Science and Engineering Jilin University Changchun 130022 P. R. China China Japan Union Hospital of Jilin University Changchun 130033 P. R. China

Magnesium-based alloys are frequently reported as potential biodegradable orthopedic implant materials. Controlling the degradation rate and mechanical integrity of magnesium alloys in the physiological environment is the key to their applications. In this study, calcium phosphate （Ca-P） coating was prepared on AZ60 magnesium alloy using phosphating technology. AZ60 samples were immersed in a phosphating solution at 37 ± 2 ℃ for 30 min, and the solution pH was adjusted to 2.6 to 2.8 by adding NaOH solution. Then, the samples were dried in an attemperator at 60 ℃. The degradation behavior was studied in vivo using Ca-P coated and uncoated magnesium alloys. Samples of these two different materials were implanted into rabbit femora, and the corrosion resistances were evaluated after 1, 2, and 3 months. The Ca-P coated samples corroded slower than the uncoated samples with prolonged time. Significant differences （p 〈 0.05） in mass losses and corrosion rates between uncoated samples and Ca-P coated samples were observed by micro-computed tomography. The results indicate that the Ca-P coating could slow down the degradation of magnesium alloy in vivo.

关键词： Ca-P coating mass loss micro-computed tomography corrosion resistance magnesium alloy

Improved Goldschmidt division method using mapping of divisors

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Science China(Information Sciences) 2013年第9期56卷 288-293页

作者： YAN Wen qu XiuJie CHEN He yu JiYang LONG Teng School of Information and Electronics Beijing Institute of Technology The Electronic Engineering Technology Research Center of China Academy of Space Tech

To achieve high precision with fewer storage resources, an improved Goldschmidt division method of using the mapping of divisors is presented. The improved division method does not need the initial approximation, which means that the look-up table can be saved. Then a mapping method is proposed to reduce the relative errors of the iteration results through multiplying the dividends and divisors by the mapping coefficients simultaneously. Since the mapping coefficients are all fixed factors, the mapping method applies CSD coding in the multiplication with fixed factors to reduce the hardware resources. Finally, using fewer hardware resources, the proposed method can achieve smaller relative errors.

关键词： Goldschmidt division method mapping of divisors CSD coding multiplication with fixed factors fewer hardware resources

Thermal properties of diamond/Al composites by pressure infiltration:comparison between methods of coating Ti onto diamond surfaces and adding Si into Al matrix

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Rare Metals 2016年第3期35卷 249-255页

作者： Cai-yu Guo Xin-Bo He Shu-Bin Ren Xuan-Hui qu Institute for Advanced Materials and Technology University of Science and Technology Beijing

This study was pertained to the effects of Ti coating on diamond surfaces and Si addition into Al matrix on the thermal conductivity（TC） and the coefficient of thermal expansion（CTE） of diamond/Al composites by pressure *** fracture surfaces,interface microstructures by metal electro-etching and interfacial thermal conductance of the composites prepared by two methods were *** results reveal that Ti coating on diamond surfaces and only12.2 wt% Si addition into Al matrix could both improve the interfacial bonding and increase the TCs of the *** the Ti coating layer introduces more interfacial thermal barrier at the diamond/Al interface compared to adding 12.2 wt% Si into Al *** diamond/Al composite with 12.2 wt% Si addition exhibits maximum TC of 534 W·m^-1·K^-1and a very low CTE of 8.9×10^-6K^-1,while the coating Ti-diamond/Al composite has a TC of 514 W·m^-1·K^-1 and a CTE of 11.0×10^-6K^-1.

关键词： Metal matrix composites Coating Thermal conductivity Coefficient of thermal expansion Pressure infiltration

Hardware-based high-performance string lookup with value retrieval using extended Bloom filter

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The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 97-101页

作者： LI Qi-yue qu yu-gui ZHAO Bao-hua Department of Electronic Engineering and Information Science University ofScience and Technology of China Hefei 230027 China Department of Computer University of Science and Technology of ChinaHefei 230027China

in network packet processing, high-performance string lookup systems are very important. In this article, an extended Bloom filter data structure is introduced to support value retrieval string lookup, and to improve its performance, a weighted extended Bloom filter （WEBF） structure is generalized. The optimal configuration of the WEBF is then derived, and it is shown that it outperforms the traditional Bloom filter. Finally, an application-specific integrated circuit （ASIC）-based technique using WEBF is outlined.

关键词： Bloom filter value retrieval string lookup Hash function ASIC

Microstructure characterization of a pressureless infiltrating oxidized SiCp preform by Al-8Mg

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 223-228页

作者： Shu-bin Ren Xiao-yu Shen Xin-bo He Xuan-hui qu School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The microstructure of a pressureless infiltrating 55vol% oxidized SiC preform by Al-8Mg alloy was characterized by transmission electron microscopy （TEM）, high resolution TEM （HRTEM）, field emission scanning electron microscopy （FE-SEM）, and X-ray diffraction. The TEM image of the interface between Al and SiC shows that the surface of SiC is covered by a rough nanocrystal layer of MgAl2O4, Al2O3, and Si, produced by the interfacial reaction of Al, Mg, and SiO2 on the surface of SiC. The Al-SiC interface is also examined by HRTEM to be better understood how MgAl2O4 and Al2O3 are produced. Dendritic Al2O3 crystals are embedded in the pores of the composite generated from the mutual bonding of SiO2 on the surface of SiC. Columnar AlN crystals of about 250 nm in length are bunched vertically on the SiC particle surface.

关键词： microstructure composites interfaces pressureless infiltration oxidation.

QoE Assessment and Prediction Method for HighDefinition Video Stream Using Image Damage Accumulation

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China Communications 2016年第7期13卷 48-59页

作者： Yang Geng Luoming Meng Yao Wang yu Yang Zhiguo qu State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China Global Energy Interconnection Research Institute Nanjing 210003China Information Security Center Beijing University of Posts and TelecommunicationsBeijing 100876China Jiangsu Engineering Center of Network Monitoring Nanjing University of Information Science and Technology Nanjing 210044 China

The accuracy of the traditional assessment method of the quality of experience(Qo E) has been facing challenges with the growth of high-definition(HD) video streaming *** display-quality damage is the main factor that affects the Qo E in HD video services through UDP network *** this paper,we introduce a novel objective factor known as image damage accumulation(IDA) to assess user's Qo E in HD video ***,this paper quantitatively analyzed the effect on user quality of experience by IDA and established a mapping relationship between mean opinion scores and ***,the probability of image damage caused by compression and transmission were *** on this analysis,an objective Qo E assessment and prediction method for HD video stream service that evaluated the user experience according to IDA are *** proposed method can achieve assessment and prediction accuracy on three distinct subjective tests.

关键词： high-definition video stream quality of experience(QoE) image damage accumulation

Numerical Study on the Aerodynamic and Fluid−Structure Interaction of An NREL-5MW Wind Turbine

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China Ocean Engineering 2024年第3期38卷 363-378页

作者： ZHAO Mi yu Wan-li WANG Pi-guang qu Yang DU Xiu-li Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China State Key Laboratory of Bridge Engineering Safety and Resilience Beijing University of TechnologyBeijing 100124China

A 5-MW wind turbine has been modeled and analyzed for fluid-structure interaction and aerodynamic *** this study, a full-scale model of a 5-MW wind turbine is first developed based on a computational fluid dynamics(CFD) approach, in which the unsteady, noncompressible Reynolds Averaged Navier-Stokes(RANS) method is used. The main focus of the study is to analyze the tower shadow effect on the aerodynamic performance of the wind turbine under different inlet flow conditions. Subsequently, the finite element model is established by considering fluid/structure interactions to study the structural stress, displacement, strain distributions and flow field information of the structure under the uniform wind speed. Finally, the fluid-structure interaction model is established by considering turbulent wind and the tower shadow effect. The variation rules of the dynamic response of the one-way and two-way fluid-structure interaction(FSI) models under different wind speeds are analyzed, and the numerical calculation results are compared with those of the centralized mass model. The results show that the tower shadow effect and structural deformation are the main factors affecting the aerodynamic load fluctuation of the wind turbine, which in turn affects the aerodynamic performance and structural stability of the blades. The structural dynamic response of the coupled model shows significant similarity, while the structural displacement response of the former exhibits less fluctuation compared with the conventional centralized mass model. The one-way fluid-structure interaction(FSI)model shows a higher frequency of stress-strain and displacement oscillations on the blade compared with the two-way FSI model.

关键词： computational fluid dynamics methods(CFD) tower shadow effect aerodynamic performance fluidstructure interaction space flow field

Promoting Environmental Risk Assessment and Control of Emerging Contaminants in China

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Engineering 2024年第6期37卷 13-17页

作者： Bin Wang Qian Sui Huijuan Liu Gang yu Jiuhui qu School of Environment Tsinghua UniversityBeijing 100084China School of Resources and Environmental Engineering East China University of Science and TechnologyShanghai 200237China Advanced Interdisciplinary Institute of Environmental and Ecology Beijing Normal UniversityZhuhai 519000China

*** In recent years,China has carried out an extensive preventative battle against air,water,and soil pollution,and the nation’s environmental quality-as reflected by conventional pollutant indicators—has significantly *** the same time,the issue of emerging contaminants(ECs)is beginning to receive increasing *** generally refer to newly discovered or noticeable pollutants that pose risks to the ecological environment or human *** they have not been included in environmental management,or existing management measures are insufficient to effectively prevent and control their *** ECs of greatest concern generally include persistent organic pollutants(POPs),endocrine-disrupting chemicals(EDCs),pharmaceuticals and personal care products(PPCPs),and *** four categories of ECs are not entirely separate,as they interrelate with each other(Fig.1).Chemical production and product usage are the main sources of *** is the world’s largest producer and consumer of bulk chemicals,and the production value of China’s chemical industry is predicted to reach 50%of the global total by 2030[1].Scientific control of ECs based on their environmental risk assessment is a necessary way to support the prevention and legal governance of ECs.

关键词： legal entirely prevention

Effect of Mg and Si on infiltration behavior of Al alloys pressureless infiltration into porous SiCp preforms

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International Journal of Minerals,Metallurgy and Materials 2011年第6期18卷 703-708页

作者： Shu-bin Ren Xiao-yu Shen Xuan-hui qu Xin-bo He School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different *** results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes *** the increase of Mg content in the Al alloys from 0wt% to 8wt%,the infiltration will become much easier,the incubation period becomes shorter and the infiltration rate is faster,but these effects are not obvious when the Mg content is higher than 8wt%.As for Si addition to the Al alloys,it has no obvious effect on the incubation period,but the infiltration rate increases markedly with the increase of Si content from 0wt% to 12wt% and the rate has no obvious change when the content is bigger than 12wt%.The effect of Mg and Si on the incubation period is related to the infiltration mechanism of Al pressureless infiltration into SiCp preforms and their impact on the infiltration rate is a combined result from viscosity and surface tension of Al melt and SiC-Al wetting ability.

关键词： metallic matrix composites infiltration aluminum alloys silicon carbide preforms