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Effects of Ultrasonic Field on Microstructures and Properties of Semi-solid AZ91D Magnesium Alloy

Journal of Wuhan University of Technology(Materials Science) 2010年第4期25卷 555-560页

作者：陈国平 Mechanical Engineering Institute Hunan Industry University(Zhuzhou) Mechanical and Electrical Engineering Institute Nanchang University

The microstructure distribution rule of semi-solid AZ91D alloy treated by ultrasonic was researched, and mechanical properies of specimens before and after ultrasonic treatment were investigated ***-solid AZ91D melt specimens were processed by ultrasonic under different powers, and its microstructures and mechanical properties at different sampling points in specimens were obtained. The experimental results show that the microstructure of AZ91D alloy at different sampling points under the same ultrasonic power is different in grain size and shape, and there is also great difference among their microstructures at the same sampling point under different ultrasonic powers. AZ91D alloy treated by ultrasonic can obtain increment in both tensile strength and plasticity. Under same ultrasonic power, mechanical properties of specimen at different sampling points have obvious difference, and regularity for change of mechanical properties everywhere is similar to regularity for change of grain size and shape everywhere.

关键词： magnesium alloy AZ91D ultrasonic treatment semi-solid structure distribution rule

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Basic properties of saline soil in Da'an, western Jilin, China

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Research in Cold and Arid Regions 2015年第5期7卷 568-572页

作者： Xin Zhou Qing Wang XueFei Zhang TianWen Yu XuDong Zhang College of Construction Engineering Jilin University

This paper studied the basic properties of saline soil at different depths of a sampling site in Da＇an, China, through field reconnaissance and laboratory analysis. A series of experiments which comprised the analyses of grain size distribution, mineral composition, soil physical properties, soluble salt concent, pH, organic content and cation exchange capacity were conducted. Through these experiments, the distribution rule of each property and their causes are discussed. These results could provide a fundamental base for the study of moisture migration.

关键词： saline soil basic properties distribution rule moisture migration

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Study on the influencing factors of rock-soil thermophysical parameters in shallow geothermal energy

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Journal of Groundwater Science and Engineering 2015年第3期3卷 256-267页

作者： ZHU Xi ZHANG Qing-lian WANG Wan-li LIU Yan-guang The Institute of Hydrogeology and Environmental Geology CAGS Shijiazhuang University of Economics

Thermophysical parameters are the main parameters affecting the utilization efficiency of shallow geothermal energy. Based on the research and evaluation data of shallow geothermal energy in capital cities of China, this paper analyzes the differences between two testing methods and finds that data measured in in-situ thermal conductivity test is closer to the actual utilization. This paper analyzes the influencing factors of thermophysical parameters from lithology, density, moisture content and porosity: The thermal conductivity coefficient of bedrock is generally higher than Quaternary system loose bed soil; as for the coefficient of bedrock, dolomite, shale and granite are higher while gabbro, sandstone and mudstone are lower; as for the coefficient of loose bed, pebble and gravel are higher while clay and silt are lower. As the particle size of sand decreases, the thermal conductivity coefficient declines accordingly. The thermal conductivity coefficient increases linearly with growing density and decreases in logarithm with growing moisture content as well as porosity; specific heat capacity decreases in logarithm with growing density, increases in power exponent with growing moisture content and decreases linearly with growing porosity. The thermal conductivity coefficient is high when hydrodynamic condition is good and vice versa. The conclusions of this paper have guiding significance for the research, evaluation and development of shallow geothermal energy in other areas.

关键词： Shallow geothermal energy Thermophysical property Influencing factor distribution rule

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The Small Sample Credit Risk Rating and its Empirical Study

The Small Sample Credit Risk Rating and its Empirical Study

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2011 International Conference on Business Management and Electronic Information(BMEI 2011)

作者： Qi Fei School of Management Dalian University of Technology Dalian P.R.China Chi Guotai School of Management Dalian University of Technology Dalian P.R.China Sui Cong School of Finance Dongbei University of Finance and Economics Dalian P.R.China

Credit risk rating is used to judge the risk degree of different enterprises and provides some references for measuring the default rates of different *** sufficient sample number can guarantee the accuracy and rationality of credit *** is very difficult to find the ideal large samples in reality,especially in the *** study finds out the distribution rule of rating scores by use of testing the score distribution of small sample commercial bank credit *** to the distribution rule,the sample data are expanded and the bank credit risk ranks are ***,this study reveals the logarithmic distribution rule of commercial bank credit scores in China by testing the distribution rule of rating *** the face of limited sample date of commercial banks,the problem how the data are expanded in credit rating is ***,the credit ranks of 41 Chinese banks who publish the annals can be fixed based on the credit scores of credit ranks of 1000 simulated banks,which solves the problem that nine credit ranks can’t be divided reasonably with small samples of 41 commercial *** this study is of importance for those countries which have few and concentrated banks to do some ratings.

关键词： Credit rating Sample test distribution rule Sample expansion

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