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Compilation of load spectrum of machining center spindle and application in fatigue life prediction
Guofa Li,Shengxu Wang,Jialong He,Kai Wu,Chuanyang Zhou 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
The load spectrum of machining center (MC) is the data basis for fatigue life prediction. A novel compiling method of dynamic cutting load spectrum of MC spindle is proposed, and then applied to the fatigue life prediction. Typical process parameters were determined based on the data collected in the user field by establishing the characteristic load distribution, and dynamic cutting load was measured using the load test platform. Mean-frequency and amplitude-frequency matrices of the load were obtained by the rainflow counting method, and mixture Weibull distribution (MWD) was used to establish the mean and amplitude distribution. Thus, the two-dimensional dynamic cutting load spectrum of spindle was compiled. The eight-level program load spectrum was established, and then applied to the spindle fatigue life prediction. The accuracy of load spectrum is improved because of the MWD, instead of single distribution, and the complete load spectrum compilation process also improves the life prediction accuracy.
A numerical method for estimating the elastic modulus of recycled concrete
Xinzhu Zhou,Jianjun Zheng,Ting Chen,Jian Zhang,Chuanyang Wang,Jiefeng Wu 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.3
This paper aims at presenting a numerical method for estimating the elastic modulus of recycled concrete with crushed aggregates. In the method, polygonal aggregates following a given sieve curve are generated, and placed into a square simulation element with the aid of the periodic boundary condition and the overlap criterion of two polygonal aggregates. The mesostructure of recycled concrete is reconstructed by embedding an old interfacial transition zone (ITZ) layer inside each recycled aggregate and by coating all the aggregates with a new ITZ layer. The square simulation element is discretized into a regular grid and a representative point is selected from each sub-element. The iterative method is combined with the fast Fourier transform to evaluate the elastic modulus of recycled concrete. After the validity of the numerical method is verified with experimental results, a sensitivity analysis is conducted to evaluate the effects of key factors on the elastic modulus of recycled concrete. Numerical results show that the elastic modulus of recycled concrete increases with the increase of the total aggregate content and the elastic moduli of old and new ITZ but decreases with increasing the replacement ratio of recycled aggregate and the thicknesses of old and new ITZ. It is also shown that, for a replacement ratio of recycled aggregate smaller than 0.3, the elastic modulus of recycled concrete is reduced by no more than 10%.
Hypoxia-induced circRNF13 promotes the progression and glycolysis of pancreatic cancer
Zhao Qiuyan,Zhu Zhonglin,Xiao Wenqin,Zong Guanzhao,Wang Chuanyang,Jiang Weiliang,Li Kai,Shen Jie,Guo Xingya,Cui Jianhua,Guo Lihong,Wan Rong 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-
Pancreatic cancer (PC) is one of the most malignant tumors. Rapid progression and distant metastasis are the main causes of patient death. Hypoxia is a hallmark of multiple cancers and is involved in tumor biology. However, little is known about the roles of circRNAs in glycolysis and hypoxia-mediated progression of PC. Here, the expression pattern of hypoxia-related circRNAs was analyzed using RNA sequencing. A unique circRNA termed circRNF13 was found to be upregulated in PC tissues and may be a potential prognostic indicator. HIF-1α and EIF4A3 are involved in regulating the biogenesis of circRNF13. Furthermore, circRNF13 was validated to exert a stimulative effect on cell proliferation, angiogenesis, invasion and glycolysis. Importantly, we found that circRNF13 promoted PDK3 levels by acting as a miR-654-3p sponge, thus promoting the PC malignant process. Collectively, our results reveal that hypoxia-induced circRNF13 mediated by HIF-1α and EIF4A3 promotes tumor progression and glycolysis in PC, indicating the potential of circRNF13 as a prognostic biomarker and therapeutic target for PC.