Papers by Keyword: Statistical Calculation

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Authors: Yuan Bin Zhang, Hui Luo, Tong Guang Zhai
Abstract: The population and size of porosities in three kinds of cast aluminum alloys, i.e. A713, A356T6-1 and A356T6-2, were statistically measured using a commercial software Spirit, and several distribution functions were tried to fit the cumulative pore size distribution data. It was found that a general extreme value (GEV) distribution function was the most appropriate function to quantify the cumulative pore size distribution in these cast aluminum alloys. The stress-number of cycles to failure (S-N) curves of these alloys were characterized by four point bend fatigue testing on MTS810 materials testing system, with the parameter f=20Hz, R=0.1, and in ambient air. The fatigue strength of A713, A356T6-1 and A356T6-2 aluminum alloy was measured to be 94.5 MPa, 150.6MPa and 117.3MPa respectively. The fatigue properties of these alloys could not be evaluated just by population and size distribution of the pores, the microstructure state, shape and position of pores, and other weakest links that may initiate a fatigue crack should be taken into account synthetically.
Authors: De Xiang Wang, Pei Qi Ge, Lei Zhang, Zhen Jie Zhu
Abstract: Sliding and plowing are discriminated based on Hertz contact, and the grain number statistics model is established considering that grain size and abrasive protrusion height fit normal distribution. The analysis shows that less than 5% of grains are contacting with workpiece in the grinding arc, about 96% of contacting grains plow and about 4% cut. Sliding grains accounting for contacting grains is about 0.2%, which is almost negligible.
Authors: Virginia Burghelea, Nela Stafie
Authors: Xin Chun Wang, Xing Hua Ma, Bing Han
Abstract: The whole unknown parameters estimation and hypothesis testing is the most common and most commonly used statistical inference,so clarify the relationship between them is very important.Clearing both unity and not uniformity will help to amend the emergence of some specious argument of statistical work. In this paper, some differences were analyzed on interval estimation and hypothesis testing of statistical inference theory,the scope of their application of two methods was discussed, the dualityof Neyman —Pearson hypothesis testing and confidence interval was described Then provided the method of determining the unknown parameters’ confidence interval in hypothesis the same time, it provided the ideas how to solve the problem of refusal field of hypothesis test througn confidence interval . As the confidence interval of the statistics varies with the selected significance level and sample size, it is heavily influenced by subjective factors.
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