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Some large values of in-situ stress and related engineering geological problems in China
Yanjun Shang,박형동,Yongyue Shi,Guangxiang Yuan,Yuanchun Sun 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.2
In recent years, different methods have been applied to in-situ stress estimation for stability analysis of increasing large-scale tunnels in China. It was found that some extraordinary stress values are mostly associated with, although not a necessity of, engineering geological problems such as collapse, rock burst and squeezing. This paper focuses on finding the relationship among abnormal in-situ stress component values. The exposure in ground surface with unloading and erosion contributes a lot to relatively higher horizontal stress and lateral coefficient values of igneous and metamorphic rocks, while this situation is not the case for sedimentary rocks. Comparing stress data and connecting some abnormal values with typical case examples for better understanding and estimating stress is the main feature of this paper.
Xueqi Shi,Weiyi Su,Hongyu Zhang,Jing Fang,Ning Xu,Yanjun Jiang,Hao Li 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
Alpha-ketoglutaric acid (a-KG) is a crucial intermediate with broad application prospects. However, thedownstream separation of a-KG from fermentation broth with low concentration and complex componentshas become the bottleneck of large-scale production. In this study, a-KG was separated from theactual fermentation broth by aqueous two-phase system (ATPS) and crystallization. The optimal ATPScomposed of acetone/(NH4)2SO4 was selected by studying the phase diagram and a-KG distributionbehavior in different organic solvents and salts/sugars. Under the optimized conditions, the purity ofa-KG products from crude fermentation broth reached 98.08%, and the one-pass extraction efficiencywas 90.52%. The removal of cell debris and soluble proteins increased with the increase of acetone and(NH4)2SO4 concentrations, with the removal ratios reaching up to 99.44% and 86.54%. In addition,92.56% of the glucose was distributed in the aqueous phase. Although the a-KG fermentation broth ismore complex than the whole-cell biotransformation, impurities in the crude fermentation broth couldbe efficiently removed and a higher a-KG distribution coefficient was obtained. Meanwhile, the recovered(NH4)2SO4 could be reused for fermentation medium. This strategy provides an economical and effectivemethod combined with upstream biosynthesis to recover a-KG and other bioproducts from crude fermentationbroth.
Xiangyang Zhou,Yanjun Shi,Lingling Li,Rui-fang Yu,Libo Zhao 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.6
This paper presents a high precision compound control scheme based on non-singular terminal sliding mode and extended state observer (ESO) for an aerial inertially stabilized platform (ISP) to suppress the effects of multi-source disturbances on the control performance of the ISP. Firstly, a non-singular terminal sliding mode controller is proposed to achieve high disturbance rejection ability, by which the multi-source disturbances are integrally suppressed as an aggregate disturbance. And then, to restrain the chattering effect of the sliding mode control, a disturbance compensation scheme based on the extended state observer is proposed. By the ESO, the disturbances are observed and compensated in real time and hence the chattering effect is significantly alleviated. Meanwhile, a parameter configuration method is proposed to simplify the ESO design. To verify the method, simulations and experiments are conducted. The results show that the proposed compound control scheme has excellent ability in both disturbance rejection and chattering reduction, by which the stabilization precision of the ISP is improved significantly.