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ENTROPY OF NONAUTONOMOUS DYNAMICAL SYSTEMS
Zhu, Yujun,Liu, Zhaofeng,Xu, Xueli,Zhang, Wenda Korean Mathematical Society 2012 대한수학회지 Vol.49 No.1
In this paper, the topological entropy and measure-theoretic entropy for nonautonomous dynamical systems are studied. Some properties of these entropies are given and the relation between them is discussed. Moreover, the bounds of them for several particular nonautonomous systems, such as affine transformations on metrizable groups (especially on the torus) and smooth maps on Riemannian manifolds, are obtained.
Entropy of nonautonomous dynamical systems
Yujun Zhu,Zhaofeng Liu,Xueli Xu,Wenda Zhang 대한수학회 2012 대한수학회지 Vol.49 No.1
In this paper, the topological entropy and measure-theoretic entropy for nonautonomous dynamical systems are studied. Some properties of these entropies are given and the relation between them is discussed. Moreover, the bounds of them for several particular nonautonomous systems, such as affine transformations on metrizable groups (especially on the torus) and smooth maps on Riemannian manifolds, are obtained.
Yi, Hao,Zhuo, Fang,Li, Yu,Zhang, Yanjun,Zhan, Wenda The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5
Instead of extracting every selected harmonic component, the current reference of selective active power filter (APF) can be also obtained by filtering out the fundamental component from distorted load current for computation efficiency. This type of mixed current reference contains kinds of harmonic components and easily involves noises. In this condition, selective harmonic compensation must be realized by the current controller. With regard that selectivity is the most significant feature of controller, this paper presents specific comparison analysis between two types of resonant controllers: proportional-resonant (PR) controller and vector-resonant (VR) controller. The comparison analysis covers the relations, performances, and stability of both controllers. Analysis results conclude that the poorer selectivity of the PR controller could be relatively improved, but limitations from system stability make the improvement hardly realized. By contrast, the VR controller exhibits excellent selectivity and is more suitable for selective APF with mixed current reference. Experimental results from laboratory prototype validate the reasonability of analysis. And the features of each resonant controller are concluded.
Hao Yi,Fang Zhuo,Yu Li,Yanjun Zhang,Wenda Zhan 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5
Instead of extracting every selected harmonic component, the current reference of selective active power filter (APF) can be also obtained by filtering out the fundamental component from distorted load current for computation efficiency. This type of mixed current reference contains kinds of harmonic components and easily involves noises. In this condition, selective harmonic compensation must be realized by the current controller. With regard that selectivity is the most significant feature of controller, this paper presents specific comparison analysis between two types of resonant controllers: proportional-resonant (PR) controller and vector-resonant (VR) controller. The comparison analysis covers the relations, performances, and stability of both controllers. Analysis results conclude that the poorer selectivity of the PR controller could be relatively improved, but limitations from system stability make the improvement hardly realized. By contrast, the VR controller exhibits excellent selectivity and is more suitable for selective APF with mixed current reference. Experimental results from laboratory prototype validate the reasonability of analysis. And the features of each resonant controller are concluded.
Experimental Study on the Effect of Black Shales and Water Interactions on Concrete
( Xin Liao ),( Qingfeng Wang ),( Sixiang Ling ),( Xiyong Wu ),( Wenda Zhang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
Black shales, usually containing pyrite, are easily oxidized and generate acidic porewater. This acidic environment is non favorable for tranditional engineering material, e.g., concrete, and is likely to affect the durability of the engineering structure. This study investigated the corrsions of concrete by acid water from black shale at different immersion depth. Electrical conductivity (EC) and pH values of the solution were monitored at intervals. Concentrations of major ion species were determined for immersion solutions. Micro-fissure development within the rock and concrete samples were determined by comparing the ultrasonic before and after the immersion tests. Mineral and strength analysis was conducted with X-ray diffraction and uniaxial compressive strength apparatus. The results indicate that: 1) capillary action was significant for the water-solid interactions of black shale and concrete, where the chemical reaction of black shale mainly occurred; 2) the immersion solution caused corrosion in the surface of black shale and concrete, which dramatically reduced the compressive strength of black shale but increased that of concrete slightly in the immersion period. This change can be attributed to the products formed by the chemical reaction between the sulfate-rich ion solution and concrete filled in pore structure.
Frequently Occurring Reconnection Jets from Sunspot Light Bridges
Tian, Hui,Yurchyshyn, Vasyl,Peter, Hardi,Solanki, Sami K.,Young, Peter R.,Ni, Lei,Cao, Wenda,Ji, Kaifan,Zhu, Yingjie,Zhang, Jingwen,Samanta, Tanmoy,Song, Yongliang,He, Jiansen,Wang, Linghua,Chen, Yaji American Astronomical Society 2018 The Astrophysical journal Vol.854 No.2