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Yinsheng Song,Guanqi Wang,Feng Li,Hao Shen,Jing Wang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10
This paper is concerned with the dynamic event-triggered H∞ control issue of singularly perturbed switched systems, in which a persistent dwell-time switching regularity is embraced. The dynamic event-triggered mechanism is introduced to reduce some unnecessary data transmitted in the communication network so as to that the system can maintain the desired performance under better resource efficiency. Under this communication mechanism, a singular perturbation parameter independent criterion is derived to guarantee the globally uniform exponential stability with an H∞ performance for the considered persistent dwell-time switched singularly perturbed systems. Based on the criterion, a method is presented for calculating the gains of the desired controller. Finally, a numerical example is provided to verify the rationality and validity of the proposed method.
Microstructural Characterization of SS304 upon Various Shot Peening Treatments
He, Yinsheng,Li, Kejian,Cho, In Shik,Lee, Chang Soon,Park, In Gyu,Song, Jung-il,Yang, Cheol-Woong,Lee, Je-Hyun,Shin, Keesam Korean Society of Microscopy 2015 Applied microscopy Vol.45 No.3
Plastic deformation was introduced to the austenitic (${\gamma}$) stainless steel of SS304 by air blast shot peening, ultrasonic shot peening, and ultrasonic nanocrystalline surface modification. Various deformation structures were formed. The hardness, the deformation structure and the underlying grain refinement mechanism were investigated. In the deformed region, planar dislocation arrays and deformation twin (DT), the DT-DT intersection and ${\varepsilon}$-martensite structures, and ${\alpha}^{\prime}$-martensite were formed in the respective regions of low, medium, and high strain. The grain refinement mechanism is found to be closely related to the 1) sub-division of coarse grains by DT, shear bands and their intersection, and 2) formation of nano-sized ${\alpha}^{\prime}$-martensite due to the high plastic deformation.
Surface nanocrystallization of pure Cu induced by ultrasonic shot peening.
Li, Kejian,He, Yinsheng,Fang, Chao,Ma, Houyu,Kim, Jaeyong,Lee, Han-Sang,Song, Jung-Il,Yang, Cheol-Woong,Lee, Je-Hyun,Shin, Keesam American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.12
<P>Peening is mainly used as a method of surface treatment for microstructural modification in order to improve surface mechanical properties. The ultrasonic shot peening (USP) technique can cause severe plastic deformation with its high strain rate on the surface of metallic parts. However, systematic studies of microstructural refinement mechanism upon plastic deformation with consideration of alloy systems are rare. In this study, USP-treated Cu samples of 99.96% purity was examined using analytical techniques, Vickers microhardness test, electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). Results of EBSD and microhardness analyses indicated grain refinement with deformation structures and hardness increase down to 400 μm in depth upon treatment. Depth specific TEM analysis of the samples revealed the steps of the grain refinement process to the formation of randomly oriented fine grains.</P>