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Zhenhua Zhang,Xiaochuan Chen,Huayan Yao,Xiang Huang,Luwang Chen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7
Jurassic Red-Bed sandstone is one of the main types of rock composing unstable slopes on both banks of the Three Gorges Reservoir (TGR) in China. It is vulnerable to tensile strength degradation when exposed to cyclic wet-dry conditions under reservoir operation. Therefore, the law behind this needs to be clarified in order to accurately evaluate the stability of a sandstone slope located in the drawdown area of the TGR. In this paper, Jurassic Red-Bed sandstone specimens from the Majiagou landslide in the TGR area were collected for experiments with cyclic wet-dry procedures. After each wet-dry cycle, efforts were made to implement splitting tests, measure clay mineral contents and ion contents in the soak solution, and observe changes in microstructures. The tensile strength is experimentally demonstrated to be a process of damage accumulation under the integrated actions of water pressure, calcite dissolution, and clay mineral hydration, among which hydration of illite contributes the most to the damage. The loss of the cement material and the cyclic expansion and shrinkage of clay minerals weaken the cementation between grains, leading to the tensile strength degradation.
Zhao, Yucheng,Chen, Hamn-Ching,Yu, Xiaochuan Techno-Press 2015 Ocean systems engineering Vol.5 No.4
The numerical simulation of wave slamming on a 3D platform deck was investigated using a coupled Level-Set and Volume-of-Fluid (CLSVOF) method for overset grid system incorporated into the Finite-Analytic Navier-Stokes (FANS) method. The predicted slamming impact forces were compared with the corresponding experimental data. The comparisons showed that the CLSVOF method is capable of accurately predicting the slamming impact and capturing the violent free surface flow including wave slamming, wave inundation and wave recession. Moreover, the capability of the present CLSVOF method for overset grid system is a prominent feature to handle the prediction of wave slamming on offshore structure.
Carbon molecular sieves from soybean straw-based activated carbon for CO2/CH4 separation
Yuxian Xu,Xiaochuan Chen,Dan Wu,Yongjin Luo,Xinping Liu,Qingrong Qian,Liren Xiao,Qinghua Chen 한국탄소학회 2018 Carbon Letters Vol.25 No.-
Soybean straw (SS)-based activated carbon was employed as a precursor to prepare carbon molecular sieves (CMSs) via chemical vapor deposition (CVD) technique using methane as carbon source. Prior to the CVD process, SS was activated by 0.5 wt% ZnCl2, followed by a carbonization at 500°C for 1 h in N2 atmosphere. N2 (77 K) adsorption-desorption and CO2 (273 K) adsorption tests were carried out to analyze the pore structure of the prepared CMSs. The results show that increasing the deposition temperature, time or methane flow rate leads the decrease in N2 adsorption capacity, micropore volume and average pore diameter of CMSs. The adsorption selectivity coefficient of CO2/CH4 achieves as high as 20.8 over CMSs obtained under the methane flow rate of 30 mL min–1 at 800°C for 70 min. The study demonstrates the prepared CMSs are a candidate adsorbent for CO2/CH4 separation.
Xiao Yue,Jiankui Chen,Yiqun Li,Rong Zou,Zhihao Sun,Xiaochuan Cao,Song Zhang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4
Skid-steered mobile robots are often used in outdoor exploration due to their robust mechanical structure and high maneuverability. When they track reference path on a slope with boundaries, ensuring the tracking accuracy and stability of the skid-steered mobile robot is the major target. However, the gravity makes the relationship between wheels and ground more complex on the slope, and variational slope angle also makes it difficult for tracking control. The common control methods focus on plane motion, where only the plane forces are taken into account and the gravity is normally ignored. It may lead to some performance limitations such as the accuracy of motion on a slope. To address these problems, a model predictive control strategy combined with a fuzzy system is proposed in this paper, which has considered the dynamics of the body and wheels on the slope. We improved the two dimensional kinematics and dynamics model of the robot, which makes the three dimensional motion control more accurate. And the control method allows the robot to adapt to slopes with different angles and to make the path tracking stable to curvature mutation. Both experiment and simulation results demonstrate the effectiveness and superiority of the proposed model and method.