A Simplified Numerical Model for Post-tensioned Steel Connections with Bolted Angles

Zhi-Hua Chen,Hongxing Li,Zhongwei Zhao,Haiqing Liu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

Post-tensioned (PT) self-centering beam–column connections has been developed for its good seismic performance. Many researchers have investigated its mechanical behavior by numerical or experimental method. Prior researches have indicated that the analysis by elaborate FE models is very time consuming. To overcome this disadvantage, a simplified numerical model was established in this paper. The accuracy of results derived by this model was validated against prior investigations on interior PT connections with top-and-seat angles. Influence of initial PT force on mechanical behavior of PT connection was investigated. The Geometric and material nonlinearities, and strands can be considered in the modeling. A planar steel frame structure was established and hysteretic analysis was conducted. Results indicated that the computational cost can be greatly reduced by this model.

Force identification technique by the homotopy method

Ma Chao,Hua Hongxing 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

Force identification problem is a well-known ill-posed problem because of the inversion process involved and the noise included in themeasured data. In this paper, a homotopy method based on L-curve criterion is proposed to deal with this issue. The validity of themethod is illustrated by both the linear and nonlinear systems in the numerical examples. Moreover, the accuracy and efficiency of theproposed method are compared with those of the traditional one and Tikhonov technique by L-curve criterion. Results show that theproposed method gives more reliable results than the other two methods.

Dynamic stiffness matrix of an axially loaded slender double-beam element

Li Jun,Hua Hongxing,Li Xiaobin 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6

The dynamic stiffness matrix is formulated for an axially loaded slender double-beam element in which both beams are homogeneous, prismatic and of the same length by directly solving the governing differential equations of motion of the double-beam element. The Bernoulli-Euler beam theory is used to define the dynamic behaviors of the beams and the effects of the mass of springs and axial force are taken into account in the formulation. The dynamic stiffness method is used for calculation of the exact natural frequencies and mode shapes of the double-beam systems. Numerical results are given for a particular example of axially loaded double-beam system under a variety of boundary conditions, and the exact numerical solutions are shown for the natural frequencies and normal mode shapes. The effects of the axial force and boundary conditions are extensively discussed.

Dynamic stiffness matrix of an axially loaded slenderdouble-beam element

Jun, Li,Hongxing, Hua,Xiaobin, Li Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.6

The dynamic stiffness matrix is formulated for an axially loaded slender double-beam element in which both beams are homogeneous, prismatic and of the same length by directly solving the governing differential equations of motion of the double-beam element. The Bernoulli-Euler beam theory is used to define the dynamic behaviors of the beams and the effects of the mass of springs and axial force are taken into account in the formulation. The dynamic stiffness method is used for calculation of the exact natural frequencies and mode shapes of the double-beam systems. Numerical results are given for a particular example of axially loaded double-beam system under a variety of boundary conditions, and the exact numerical solutions are shown for the natural frequencies and normal mode shapes. The effects of the axial force and boundary conditions are extensively discussed.

Engineering a High-Affinity PD-1 Peptide for Optimized Immune Cell-Mediated Tumor Therapy

Yilei Chen,Hongxing Huang,Yin Liu,Zhanghao Wang,Lili Wang,Quanxiao Wang,Yan Zhang,Hua Wang 대한암학회 2022 Cancer Research and Treatment Vol.54 No.2

Purpose The purpose of this study was to optimize a peptide (nABP284) that binds to programmed cell death protein 1 (PD-1) by a computer-based protocol in order to increase its affinity. Then, this study aimed to determine the inhibitory effects of this peptide on cancer immune escape by coculturing improving cytokine-induced killer (ICIK) cells with cancer cells. Materials and Methods nABP284 that binds to PD-1 was identified by phage display technology in our previous study. AutoDock and PyMOL were used to optimize the sequence of nABP284 to design a new peptide (nABPD1). Immunofluorescence was used to demonstrate that the peptides bound to PD-1. Surface plasmon resonance was used to measure the binding affinity of the peptides. The blocking effect of the peptides on PD-1 was evaluated by a neutralization experiment with human recombinant programmed death-ligand 1 (PD-L1) protein. The inhibition of activated lymphocytes by cancer cells was simulated by coculturing of human acute T lymphocytic leukemia cells (Jurkat T cells) with human tongue squamous cell carcinoma cells (Cal27 cells). The anticancer activities were determined by coculturing ICIK cells with Cal27 cells in vitro. Results A high-affinity peptide (nABPD1, KD=11.9 nM) for PD-1 was obtained by optimizing the nABP284 peptide (KD=11.8 μM). nABPD1 showed better efficacy than nABP284 in terms of increasing the secretion of interkeulin-2 by Jurkat T cells and enhancing the in vitro antitumor activity of ICIK cells. Conclusion nABPD1 possesses higher affinity for PD-1 than nABP284, which significantly enhances its ability to block the PD-1/PD-L1 interaction and to increase ICIK cell-mediated antitumor activity by armoring ICIK cells. PurposeThe purpose of this study was to optimize a peptide (nABP284) that binds to programmed cell death protein 1 (PD-1) by a computer-based protocol in order to increase its affinity. Then, this study aimed to determine the inhibitory effects of this peptide on cancer immune escape by coculturing improving cytokine-induced killer (ICIK) cells with cancer cells.Materials and MethodsnABP284 that binds to PD-1 was identified by phage display technology in our previous study. AutoDock and PyMOL were used to optimize the sequence of nABP284 to design a new peptide (nABPD1). Immunofluorescence was used to demonstrate that the peptides bound to PD-1. Surface plasmon resonance was used to measure the binding affinity of the peptides. The blocking effect of the peptides on PD-1 was evaluated by a neutralization experiment with human recombinant programmed death-ligand 1 (PD-L1) protein. The inhibition of activated lymphocytes by cancer cells was simulated by coculturing of human acute T lymphocytic leukemia cells (Jurkat T cells) with human tongue squamous cell carcinoma cells (Cal27 cells). The anticancer activities were determined by coculturing ICIK cells with Cal27 cells <i>in vitro</i>.ResultsA high-affinity peptide (nABPD1, K_D=11.9 nM) for PD-1 was obtained by optimizing the nABP284 peptide (K_D=11.8 μM). nABPD1 showed better efficacy than nABP284 in terms of increasing the secretion of interkeulin-2 by Jurkat T cells and enhancing the <i>in vitro</i> antitumor activity of ICIK cells.ConclusionnABPD1 possesses higher affinity for PD-1 than nABP284, which significantly enhances its ability to block the PD-1/PD-L1 interaction and to increase ICIK cell-mediated antitumor activity by armoring ICIK cells.

Vibrations characteristics of joined cylindrical-spherical shell with elastic-support boundary conditions

Shihao Wu,Yegao Qu,Hongxing Hua 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

Based on the Reissner-Naghdi’s thin shell theory, this paper concentrates on the free vibration of a joined cylindrical-spherical shell with elastic-support boundary conditions by a domain decomposition method. The joined shell is first separated from the elastic-support boundary and then subdivided into some cylindrical and spherical shell segments along the axis of revolution. The elastic-support boundary is regarded as a combination of distributed linear springs and can be treated as a special interface as well as the interface between two adjacent shell segments. Through the variational operation of the whole energy functional, the discretized equations of motion are derived by the expansions of the displacement field for each shell segment with Fourier series and Chebyshev orthogonal polynomials in the circumferential and longitudinal direction, respectively. To analyze the numerical convergence and precision of the present method, a number of case studies have been conducted and the solutions are compared with those derived by ANSYS and those presented in the previous literature to confirm the reliability and accuracy.

On the characteristics of an ultra-low frequency nonlinear isolator using sliding beam as negative stiffness

Xiuchang Huang,Xintian Liu,Hongxing Hua 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.3

A novel structured ultra-low frequency nonlinear passive isolator is presented. The isolator is composed of a knife-edge supported slidingbeam which offers negative stiffness and a vertical mechanical spring in parallel to get quasi-zero dynamic stiffness. The static characteristicsof the isolator are studied. Assuming light viscous damping, the dynamic behavior is investigated and the response under harmonicexcitation is derived using a simple approximation. Frequency response curves (FRCs), which exhibit complex double jump phenomenon,are obtained by harmonic balance method (HBM). The limitation of the excitation force level is obtained. The force transmissibilityis derived and compared with an equivalent linear system with the same damping ratio. The isolation performance of the nonlinearisolator is shown to outperform the linear system for providing a wider isolation region. The influence of system parameters on thetransmissibility is examined and some useful guidelines are given.

Dynamic modeling and analysis of axial vibration of a coupled propeller and shaft system

Chenyang Li,Xiuchang Huang,Hongxing Hua 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

The dynamic and acoustic characteristics of a coupled propeller and shaft system which is modeled by the transfer matrix method are studied. The elasticity of the propeller is taken into consideration by employing the equivalent reduced modeling method. Thus the influence of the elastic propeller on the vibro-acoustic responses of the coupled system is investigated. To reduce the axial vibration of the coupled propeller-shaft system, the influence and location of the vibration isolator on the structural and acoustic responses is presented. Simulation results demonstrate that utilizing the relationship between the natural frequency of the propeller and the resonance frequency range of the shaft can control the vibration of the coupled system without other vibration control method. Utilizing a vibration isolator is another effective way to control vibration. The optimal position for the isolator installed between the shaft and the thrust bearing is investigated.

Transverse impact characteristics of a rubber pipe expansion joint

Yong Chen,Wang Yu,ZhiYi Zhang,Hongxing Hua 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.6

The transverse impact characteristics of a rubber pipe expansion joint are studied. A pair of joints assembled end to end with an inserted middle mass is tested on a drop shock testing machine. Based on the test results, an equivalent fixed-fixed beam model with polynomial stiffness and damping is applied to predict the transverse impact response and identify the nonlinear impact parameters. The least square residual between the computed and test results is defined to drive the identification optimization. The response surface methodology in combination with the generalized reduced gradient method is used to search the best matching coefficients. Final results show that the equivalent bending stiffness of the tested rubber expansion joint gradually decreases with the transverse deformation and is greatly influenced by its internal working pressure.