In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and...In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances.展开更多
Dear Editor,Hepatitis C virus（HCV）is a positive-strand RNA virus that belongs to the genus Hepacivirus within the Flaviviridae family.HCV causes chronic liver diseases,and185 million people are infected（Messina et ...Dear Editor,Hepatitis C virus（HCV）is a positive-strand RNA virus that belongs to the genus Hepacivirus within the Flaviviridae family.HCV causes chronic liver diseases,and185 million people are infected（Messina et al.,2015）.Currently,there is no approved vaccine to prevent hepatitis C.HCV induces autophagy through elevating reactive oxygen species（ROS）levels via the unfolded protein response （UPR） or via direct interference with the autophagic pathway.展开更多
A nanopositioning system of both millimetric stroke and nanometric tracking accuracy is a key component for nanofabrication in many applications. In this paper, a novel bi-axial beam-flexure nano servo stage is propos...A nanopositioning system of both millimetric stroke and nanometric tracking accuracy is a key component for nanofabrication in many applications. In this paper, a novel bi-axial beam-flexure nano servo stage is proposed to support a direct writing system for femtosecond laser nanofabrication. The important features of the stage lie in: a mirror symmetric instead of rotational symmetric configuration is adopted to restrict cross axis coupling, and a novel Z-shaped guidance module is proposed to achieve relative large linear stiffness range, in addition a redundant constraints module is introduced to increase off-axis stiffness of the stage. Mechanical analysis and system identification are provided, with which a feedback control algorithm demonstrates the tracking capability for laser fabrication purposes. Based on the fabricated XY nano-stage, real time control and measurements are deployed, demonstrating the millimetric operating workspace and 77.8 nm(RMS) error of tracking a circular trajectory.展开更多
基金The National Basic Research Program of China (973 Program) (No. 2005CB221505)Open Fund of Provincial Open Laboratory for Control Engineering Key Disciplines (No. KG2009-02)
文摘In order to deal with the dynamic positioning system control problems of dredgers working under strong dredging reaction or harsh environments,an adaptive backstepping method is proposed.Disturbances are estimated and compensated for by the adaptive method without extra sensors on dredging equipment,and the control mechanism is simplified.Adaptive control is used to compensate for the reaction and environmental disturbances on the dredger,so the dredger can maintain the desired position with a minimum error and shock.The proposed adaptive robust controller guarantees the global asymptotic stability of the closed-loop system and rapid position tracking of the dredger.The simulation results show that the proposed controller has superior performance in position tracking and robustness to large disturbances.
基金supported by grants from the National Natural Science Foundation of China(81471955,81672035,81301438)the CAMS Innovation Fund for Medical Sciences(CIFMS)(2016-I2M-3-020)+2 种基金the National Key Plan for Research and Development of China(2016YFD0500300)the Program for Changjiang Scholars and Innovative Research Team in University(IRT13007)the Fundamental Research Funds for the Central Universities,the PUMC Youth Fund(3332016085)
文摘Dear Editor,Hepatitis C virus（HCV）is a positive-strand RNA virus that belongs to the genus Hepacivirus within the Flaviviridae family.HCV causes chronic liver diseases,and185 million people are infected（Messina et al.,2015）.Currently,there is no approved vaccine to prevent hepatitis C.HCV induces autophagy through elevating reactive oxygen species（ROS）levels via the unfolded protein response （UPR） or via direct interference with the autophagic pathway.
基金supported by Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry(Grant No.20121028120)the National Natural Science Foundation of China(Grant No.61327003)+4 种基金the Open Foundation of the State Key Laboratory of Fluid Power andMechatronic Systems(Grant No.GZKF-201413)the Fundamental Research Funds of Shandong University(Grant No.2015JC034)the National Key Basic Research Program of China(Grant No.2015CB059900)Beijing Natural Science Foundation(Grant No.3162019)the Fundamental Research Funds of Beihang University(Grant No.74003401)
文摘A nanopositioning system of both millimetric stroke and nanometric tracking accuracy is a key component for nanofabrication in many applications. In this paper, a novel bi-axial beam-flexure nano servo stage is proposed to support a direct writing system for femtosecond laser nanofabrication. The important features of the stage lie in: a mirror symmetric instead of rotational symmetric configuration is adopted to restrict cross axis coupling, and a novel Z-shaped guidance module is proposed to achieve relative large linear stiffness range, in addition a redundant constraints module is introduced to increase off-axis stiffness of the stage. Mechanical analysis and system identification are provided, with which a feedback control algorithm demonstrates the tracking capability for laser fabrication purposes. Based on the fabricated XY nano-stage, real time control and measurements are deployed, demonstrating the millimetric operating workspace and 77.8 nm(RMS) error of tracking a circular trajectory.
