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An Improved Solution for Beam on Elastic Foundation using Quintic Displacement Functions
Tongji Univ,Youquan Feng,Wenya Shu 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2
The theory of beam on elastic foundation is a simple and popular analytic approach for computing the response of laterally loaded piles. For a laterally loaded pile with constant subgrade reaction coefficient, an analytical solution can be easily deduced based on the theory of beam on elastic foundation when the load distribution and boundary condition are simple. However, when the subgrade reaction coefficient increases linearly with the depth or when the constraint condition is complex, an approximate solution can only be obtained by numerical method. At present, the node-spring simulation method and the modifying stiffness matrix method are two main solution methods for beam on elastic foundation with a nonuniform distribution of subgrade reaction coefficient, but a large number of elements are necessary for obtaining a sufficient calculation accuracy. Based on the Winkler elastic foundation model, an improved Finite Element (FE) method for the laterally loaded pile on an elastic foundation with a linearly distributed modulus of the subgrade reaction is proposed. A quintic displacement function is proposed as an approximate solution, and the weighted residual method is used for solving differential equations. The corresponding element stiffness matrix and nodal force vector are derived, and a more accurate nodal displacement, element internal force and displacement distribution can then be obtained by employing fewer elements. Three beams on elastic foundations under different boundaries and loading conditions are taken as typical examples to compare the difference of the calculation accuracy between the improved method and the node-spring simulation method. A laterally loaded pile is analyzed by the improved method, and the numerical results show that two elements for one soil layer can provide a sufficient calculation accuracy.
Jingang Xiong,Moqiang Xiong,Youquan Liu,Xiang Li,Shujun Hu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.2
A novel self-centering frame with Y-eccentrically braced structure (SC-YEBFs) has been proposed in this paper to solve the problem that the storey drift of structure may exceed the specified limit in standards when self-centering beam-column joints are applied in high-rise and larger spans buildings, and the SC-YEBFs not only has the self-centering performance of self-centering frame system, but also has the high lateral stiffness and energy dissipating capacity of Y-Eccentrically braced frame. To study the lateral load behavior and influencing factors of SC-YEBFs, cyclic loading tests of two scaled specimens of SC-YEBFs substructure (SCS) were conducted, and seven finite element models corrected by the experiment were established to perform parametric analysis. The experiment and finite element analysis results indicated that the shear link has greatly increased the lateral stiffness and energy dissipating capacity of the self-centering structure, at the same time, it has maintained a good self-centering performance and replace ability. With an increase in the cross-sectional area and initial prestress of post-tensioned steel strands, the lateral load capacity and self-centering performance can be improved. The self-centering performance can be effectively improved by reducing the friction coefficient at the rotation connections. SC-YEBFs further extending the application field of self-centering structural systems, and making it possible to be applied to high-rise and larger spans structures.
Aminated cassava residue-based magnetic microspheres for Pb(II) adsorption from wastewater
Xinling Xie,Jie Huang,Youquan Zhang,Zhangfa Tong,Anping Liao,Xingkui Guo,Zuzeng Qin,Zhanhu Guo 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.2
Aminated cassava residue magnetic microspheres (ACRPM) were synthesized via an inverse emulsion method by using chemically modified cassava residue as a crude material, and acrylic acid (AA), acrylamide (AM), and methyl methacrylate (MMA) as monomers and a polyethylene glycol/methanol system (PEG/MeOH) as the porogen. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption and vibrating sample magnetometry (VSM) were used to characterize the ACRPM. The results indicated that amino groups were grafted to the cassava residue magnetic microspheres, and the Fe3O4 nanoparticles were encapsulated in the microspheres. After porogen was added, the particle size of the ACRPM decreased from 16.5 μm to 150 nm with a pore volume of 0.05510m3/g, and the specific surface area of the ACRPM increased from 3.02 to 12.34m2/g. The ACRPM were superparamagnetic, and the saturation magnetization was 9.8 emu/g. The maximum adsorption capacity of Pb(II) on the ACRPM was 390mg/g. The ACRPM exhibited a large specific surface area and provided many adsorption sites for metal ion adsorption, which favored a high adsorption capacity. Additionally, the Pb(II) adsorption process was fitted to pseudo-second-order kinetic and Langmuir isothermal adsorption models. This suggests that the Pb(II) adsorption process was dominated by a chemical reaction process and that chemisorption was the rate-controlling step during the Pb(II) removal process. In addition, the adsorbent exhibited good stability after six consecutive reuses.
Liu, Bijin,Fu, Danjuan,Zhang, Youquan,Chen, Xiaoyun The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.-
Taking the cylindrical float of the floating fence of a floating litter collection device as the research object, based on the shallow immersion characteristics of the cylindrical float, the Morison equation is modified, and the interaction between regular waves and the partially immersed horizontal cylindrical float is discussed in combination with scale model test. The results show that the modified Morison equation can accurately predict the wave force of the horizontal cylindrical float and reveal the influence of amplitude, immersion depth and period on the wave force of the cylindrical float. For partially immersed cylindrical floats, the wave force increases with the increase in wave height and decays with the increase in period. The positive value distribution of the wave force is larger than that of the negative direction, and the difference between the positive and negative directions is mainly affected by the immersion depth.
Changli Hu,Xuede Wang,Guoyu Wang,Youquan Cao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1
The objective of this paper is to investigate the cavity shedding dynamics in unsteady cavitating flows around an axisymmetric body with a blunt headform. A high-speed video camera is used to record the cavity evolution process. The numerical simulations are performed based on the homogenous method coupled with a modified PANS (Partially-averaged Navier-Stokes) turbulence model and Zwart cavitation model. The results show that the predicted time-evolution process of cavity agree fairly well with the corresponding experimental data for two different cavitation numbers ( s = 0.7 and s = 0.6 ). Compared to that of s = 0.6 , the cavity shedding behavior of s = 0.7 presents more fluctuations and instabilities. To elucidate the different shedding structures, the Lagrangian coherent structures (LCS) and particle trajectory methods are also utilized here. It is found that the particle tracers respectively demonstrate the cavity shedding behaviors of conjunction at s = 0.6 and rolling up at s = 0.7 . Moreover, the LCS distributions vary with the timeevolution of vortex structures. The particle trajectories can illustrate the upstream and downstream vortex structures connect together at s = 0.6 but separate at s = 0.7 , which highly consistent with the cavity shedding behaviors.
Liu, Bijin,Fu, Danjuan,Zhang, Youquan,Chen, Xiaoyun The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.1
Taking the cylindrical float of the floating fence of a floating litter collection device as the research object, based on the shallow immersion characteristics of the cylindrical float, the Morison equation is modified, and the interaction between regular waves and the partially immersed horizontal cylindrical float is discussed in combination with scale model test. The results show that the modified Morison equation can accurately predict the wave force of the horizontal cylindrical float and reveal the influence of amplitude, immersion depth and period on the wave force of the cylindrical float. For partially immersed cylindrical floats, the wave force increases with the increase in wave height and decays with the increase in period. The positive value distribution of the wave force is larger than that of the negative direction, and the difference between the positive and negative directions is mainly affected by the immersion depth.
PRR11 and SKA2 gene pair is overexpressed and regulated by p53 in breast cancer
Wang, Yitao,Zhang, Chunxue,Mai, Li,Niu, Yulong,Wang, Yingxiong,Bu, Youquan Korean Society for Biochemistry and Molecular Biol 2019 BMB Reports Vol.52 No.2
Our previous study found that two novel cancer-related genes, PRR11 and SKA2, constituted a classic gene pair that was regulated by p53 and NF-Y in lung cancer. However, their role and regulatory mechanism in breast cancer remain elusive. In this study, we found that the expression levels of PRR11 and SKA2 were upregulated and have a negative prognotic value in breast cancer. Loss-of-function experiments showed that RNAi-mediated knockdown of PRR11 and/or SKA2 inhibited proliferation, migration, and invasion of breast cancer cells. Mechanistic experiments revealed that knockdown of PRR11 and/or SKA2 caused dysregulation of several downstream genes, including CDK6, TPM3, and USP12, etc. Luciferase reporter assays demonstrated that wild type p53 significantly repressed the PRR11-SKA2 bidirectional promoter activity, but not NF-Y. Interestingly, NF-Y was only essential for and correlated with the expression of PRR11, but not SKA2. Consistently, adriamycin-induced (ADR) activation of endogenous p53 also caused significant repression of the PRR11 and SKA2 gene pair expression. Notably, breast cancer patients with lower expression levels of either PRR11 or SKA2, along with wild type p53, exhibited better disease-free survival compared to others with p53 mutations and/or higher expression levels of either PRR11 or SKA2. Collectively, our study indicates that the PRR11 and SKA2 transcription unit might be an oncogenic contributor and might serve as a novel diagnostic and therapeutic target in breast cancer.