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Austenite Grain Growth Behavior of 30BF Steel Before Rough Rolling
Yong‑feng Chen,Jian‑bo Xie,Yan‑xin Wu,Jian‑xun Fu 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
To investigate the eff ect of heat treatment on the grain size of austenite in 30BF steel, the comparisons of the morphologiesand sizes of austenite grains between heating samples were made with a high-temperature electric resistance furnace, andthe austenite growth models were built with method of mathematics. The results show that most grains in original specimenwith the sizes below 70 μm uniformly distributed. At a heating rate ( v ) of 10 °C/s, the grain size ( d ) value under a certain time( t ) increased by 60–100 μm with raising temperature ( T ) from 850 to 1100 °C, whereas the d value under a certain T merelyincreased by 70–120 μm with raising time to 60 min. Under v = 0.1 °C/s, T = 850 °C, and t = 0 s, the occupied ratio of grainswith sizes of 40–50 μm was 0.165, whereas at 900 °C, the occupied ratio was 0.125. The evolutions of ln (d5.8− d5.80 ) with1/ T were in negative linear correlations, whereas the ln (d5.8− d5.80 ) with ln t were in positive linear correlations. To sum up,the grain growth behavior of steel was elucidated.
Xin Li,Zhina Lian,Bo Dong,Yong Xu,Qiang Yong,Shiyuan Yu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.9
Aqueous two-phase system (ATPS) was applied for extraction bioconversion of xylan by xylanase from Trichoderma viride. Phase diagrams for poly (ethylene glycol) (PEG) and sodium citrate were determined at room temperature. The ATPS composed of 12.99% (w/w) PEG6000 and 12.09% (w/w) sodium citrate was favorable for partition of xylanase and used for extraction bioconversion of xylan. Batch hydrolysis demonstrated that higher concentrations of xylobiose and xylotriose were obtained in the PEG6000/sodium citrate ATPS compared to those in the aqueous system. These results present the potential feasibility of production of xylo-oligosaccharides by extraction bioconversion in ATPS.
Xin, Yong,Wang, Jia-Yang,Li, Liang,Tang, Tian-You,Liu, Gui-Hong,Wang, Jian-She,Xu, Yu-Mei,Chen, Yong,Zhang, Long-Zhen Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.3
Objective: To make sure the feasibility with $^{18F}FDG$ PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Methods: Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and $^{18F}FDG$ PET/CT). The dose distributions of the various regional were realized by SMART. Results: The absolute mean errors of interest area were $2.39%{\pm}0.66$ using 0.6cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Conclusions: Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.
Three-dimensional Seismic Displacement Analysis of Rock Slopes based on Hoek-Brown Failure Criterion
Yong-xin Li,Xiao-li Yang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11
Seismic force is one of the main factors resulting in the slip failure of steep rock slopes. In this paper, the seismic displacement analysis of rock slopes is carried out by virtue of the kinematical theorem of limit analysis and the Newmark method. It is assumed that the slope has a curvilinear cone-shaped failure mechanism and its materials are subjected to the Hoek-Brown failure criterion. The generalized tangential technique is employed to obtain equivalent parameters from the Hoek-Brown criterion. According to the three-dimensional failure mechanism, the internal energy dissipation and external work are respectively calculated, and the effect of horizontal seismic force is included by using the equivalent pseudo-static method. Subsequently, the yield acceleration is calculated for three-dimensional failure mechanism, and the results are shown to be valid when compared with the previous solutions. Parameter analysis is used to represent how the Hoek-Brown criterion parameters impact on the yield acceleration. The failure mechanism is also obtained during the process of limit analysis, and a dimensionless coefficient is adopted to investigate the influence of it on the seismic displacements of slopes. The results of calculations are given for a series of actual seismic waves and compared with the results calculated from empirical formula.
Stability Analysis of Crack Slope Considering Nonlinearity and Water Pressure
Yong-xin Li,Xiao-li Yang 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.6
The soil slopes tend to induce the appearance of tension cracks at the top of slope under various factors, which poses an adverse impact on slope stability. Based on Power-Law nonlinear failure criterion, kinematical approach is adopted in this paper to investigate the effects of underground water and vertical tension cracks on stability of slopes. Notice that the tension cracks tend to propagate vertically, and thus a novel failure mechanism composed by the tension crack and logarithmic spiral shear slide plane is postulated. Theoretically, the worst position of crack propagation makes the stability factor minimal, and the failure surfaces can be obtained under different conditions through optimization. According to the proposed mechanism and nonlinear Mohr-Coulomb strength criterion, the stability factor and safety coefficient of slopes are derived. Subsequently, sensitivity analysis with respect to specific examples is conducted to analyze the influence of tension cracks, nonlinear strength parameters and pore water pressure on the slope stability. The results indicate that slope stability weakens gradually at the presence of tension cracks, and the changing degree is more evident with the increase of the slope angle. Meanwhile, nonlinear parameters have more significant impact on the safety factor with the decreasing value of the slope angle. However, the bigger the slope angle, the greater the height of tension cracks, and therefore the more obvious influence of pore water pressure on slope stability. When the slope angle approaches to be vertical, the height of tension cracks increases sharply. As a matter of fact, the height of tension cracks is highly related to geometrical conditions, strength parameters and water effect, which build a mutual relationship to determine slope stability.