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Guo, Yanping,Han, Xiaohu,Wei, Wenying The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.5
In this paper, a new fixed point theorem in cone is applied to obtain the existence of at least one positive pseudo-symmetric solution for the second order three-point boundary value problem {x" + f(t, x, x')=0, t $\in$ (0, 1), x(0)=0, x(1)=x($\eta$), where f is nonnegative continuous function; ${\eta}\;{\in}$ (0, 1) and f(t, u, v) = f(1+$\eta$-t, u, -v).
Yanping Guo,Xiaohu Han,Wenying Wei 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.5
In this paper, a new fid point theorem in cone is applied to obtain the existence of at least one positive pseudo-symmetric solution for the second order three-point boundary value problem [수식]where f is nonnegative continuous function; η∈(0,1) and f(t,u,v) =f(1+η-t, u, -v).
Qing Guo,Zhenlei Chen,Yao Yan,Wenying Xiong,Dan Jiang,Yan Shi 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2
Lower limb exoskeleton is a typical wearable robot to assist human motion and improve physiological power. However, the control performance and stability are affected by some unknown model parameters and control algorithms. Therefore, it is necessary to investigate the model parametric identification and the control design of lower extremity exoskeleton. Firstly, the two degree-of-freedom (DoF) exoskeleton model is constructed by the Lagrange technique. Then the biogeography-based learning particle swarm optimization (BLPSO) is used to optimize the B-spline function parameters and the smooth stimulated trajectories is designed. Meanwhile, the BLPSO is also adopted to identify unknown model parameters of the exoskeleton based on the torques and the joint angles. To decline the negative effect of parametric identification error of exoskeleton, the passive backstepping controller is proposed to improve the tracking performance of human-robot motion. Furthermore, the active admittance controller is adopted to improve the motion comfort of tester. Finally, the comparative experimental results are verified on the platform, which show the BLPSO algorithm has better parametric identification accuracy than PSO and GA. Furthermore, the comparative results have verified that the proposed controller can improve the tracking behavior and reduce the human-robot interaction torque in wearable motion.
Yibo Yang,Baixi Chen,Weizhen Zeng,Yanjun Li,Qiaohui Chen,Wenying Guo,Hengchang Wang,Yingqin Chen 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.5
To reduce the cost of lightweight concrete (LWC) partition panels and to address recycling concrete waste, this work utilized completely recycled fine aggregate (CRFA) to replace the natural fine aggregate and ceramsite in the preparation of LWC and LWC partition panels. To this end, an autoclave-free curing process and an air-entraining agent were used to prepare the CRFA-LWC. The workability, compressive strength, drying shrinkage, and pore structure of the CRFA-LWC and the performance of the CRFA-LWC partition panels were then investigated. The results show that the optimal ratio of the CRFA to the cement is 2.2 for the lightweight concrete, and the optimal panel cross section is a rounded rectangular one. All the pores in the CRFA-LWC have a diameter of smaller than 0.17 mm, and the diameter of 89% of them is less than 0.05 mm. In order to satisfy the drying shrinkage requirements stipulated by Chinese code JC/T 169-2016, the CRFA-LWC should be cured for at least 10 days. The economic analysis concludes that the material cost of CRFA-LWC is 40% lower than that of the autoclaved ceramsite concrete. In addition, utilizing CRFA in lightweight concrete can ease the shortage of natural aggregate.
Performances of Concrete Columns with Modular UHPC Permanent Formworks Under Axial Load
Yibo Yang,Baixi Chen,Yong Chen,Huanyang Zhou,Fucai Liu,Xiangming Xie,Junsheng Chen,Wenying Guo,Hengchang Wang 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.5
This research proposed the modular prefabricated permanent formwork system made of ultra-high-performance concrete (UHPC). Two kinds of modular formwork shapes were designed: the flat formwork and the ribbed. The experimental investigation on the axial compression performance of the composite columns that consist of the normal strength concrete (NSC) core and the modular UHPC permanent formwork was demonstrated. Compared with the flat formwork, the ribbed formwork exhibited better bonding with the NSC core. As observed from the test results, the composite column with the ribbed formwork presented a similar axial behavior as the NSC column with a slight improvement in ultimate loads. Therefore, the modular UHPC ribbed permanent formwork could be regarded as the additional cover to the conventional NSC column. In addition, the finite element analysis (FEA) model was also developed to simulate the composite columns numerically. The predicted capacities agreed with the experimental results, which validated the numerical models. The crack pattern estimated by the FEA model revealed that the interaction between the permanent formwork and the inner concrete introduced many tiny cracks to the concrete core. However, as protected by the UHPC permanent formwork, the overall durability of the composite columns can still be enhanced.