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Stability Analysis of Switched Delay Systems with All Subsystems Unstable
Guang-Deng Zong,Qingzhi Wang,Haibin Sun 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.5
The stability problem of switched delay systems with all subsystems unstable is investigated in this paper. A sufficient criterion is firstly proposed to guarantee asymptomatic stability of nonlinear switched delay systemswith all subsystems unstable, where the stabilization property of switching behaviors is exploited to compensate thedivergence of states. Then by constructing multiple discretized Lyapunov-Krasovskii functionals, stability criteriaare developed for linear switched time-invariant and time-varying delay systems with all subsystems unstable. Finally, two examples are provided to illustrate the feasibility, superiority and application of the proposed approach.
Impact effect analysis for hangers of half-through arch bridge by vehicle-bridge coupling
Shao, Yuan,Sun, Zong-Guang,Chen, Yi-Fei,Li, Huan-Lan Techno-Press 2015 Structural monitoring and maintenance Vol.2 No.1
Among the destruction instances of half-through arch bridges, the shorter hangers are more likely to be ruined. For a thorough investigation of the hanger system durability, we have studied vehicle impact effect on hangers with vehicle-bridge coupling method for a half-through concrete-filled-steel-tube arch bridge. A numerical method has been applied to simulate the variation of dynamic internal force (stress) in hangers under different vehicle speeds and road surface roughness. The characteristics and differences in impact effect among hangers with different length (position) are compared. The impact effect is further analyzed comprehensively based on the vehicle speed distribution model. Our results show that the dynamic internal force induced by moving vehicles inside the shorter hangers is significantly greater than that inside the longer ones. The largest difference of dynamic internal force among the hangers could be as high as 28%. Our results well explained a common phenomenon in several hanger damage accidents occurred in China. This work forms a basis for hanger system's fatigue analysis and service life evaluation. It also provides a reference to the design, management, maintenance, monitoring, and evaluation for this kind of bridge.
Separation of arenols from a low-temperature coal tar by liquid-liquid extraction
Hua-Shuai Gao,Zhi-Min Zong,Zheng Yang,Dao-Guang Teng,Xiu-Hua Sun,Li Yan,Xian-Yong Wei,Qing-Jie Guo,Tian-Sheng Zhao,Hong-Cun Bai 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.5
Low-temperature coal tar (LTCT) is a sticky liquid mixture produced mainly from coal pyrolysis, which contains various value-added chemicals (VACs). Liquid-liquid extraction is considered as one of the green and effective ways to explore the organic composition and separate the VACs from LTCT. Herein, petroleum ether, methanol, and carbon disulfide were used to extract arenols from a LTCT. As a result, the relative content and absolute content of arenols extracted from the LTCT are ca. 96.3% and 85.9%, respectively. Among them, p-cresol is predominant, accounting for 22.2%. The isolated contents of arenols are up to 84.6%. Moreover, a kilogram-scale operation was carried out under the same conditions, which offers a potential application in industrial production.