Metallurgical equipment is subjected to severe working conditions and the components suffer from various types of physical damages such as abrasion,corrosion and crack. Advanced surface engineering technologies and re...Metallurgical equipment is subjected to severe working conditions and the components suffer from various types of physical damages such as abrasion,corrosion and crack. Advanced surface engineering technologies and resistant coatings on the damaged surface can improve surface properties, extend service lives, reduce maintenance costs and improve product quality in the metallurgical industry. This paper introduces remanufacturing technologies, including electroplating, overlaying welding, thermal spraying and laser surface cladding and their applications in the metallurgical industry, and analyzes the development tendency and prospect of remanufacturing technologies.展开更多
Maintenance of high performance formation control is important for low Earth orbit (LEO) formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear a...Maintenance of high performance formation control is important for low Earth orbit (LEO) formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear and important perturbations affecting the formation configuration,such as J 2 and atmospheric drag,are analyzed as disturbances.Global navigation satellite system based relative positioning with nonlinear filtering is adopted to provide state information associated with the perturbations.By combining disturbance observer based control with H ∞ state feedback,a composite disturbance attenuation controller is proposed for maintenance of continuous and accurate formation.With consideration of precise control relying on micro thrusters,a composite disturbance attenuation based saturated controller is designed and its stability is proved.Finally,through numerical simulations,we demonstrate that control accuracy is improved after effectively avoiding perturbations and that stabilization can be satisfied using this method.展开更多
文摘Metallurgical equipment is subjected to severe working conditions and the components suffer from various types of physical damages such as abrasion,corrosion and crack. Advanced surface engineering technologies and resistant coatings on the damaged surface can improve surface properties, extend service lives, reduce maintenance costs and improve product quality in the metallurgical industry. This paper introduces remanufacturing technologies, including electroplating, overlaying welding, thermal spraying and laser surface cladding and their applications in the metallurgical industry, and analyzes the development tendency and prospect of remanufacturing technologies.
基金supported by the National High-Tech R & D Program (863) of China (No.2008AA12A216)the National Basic Research Program (973) of China (No.2009CB72400101C)
文摘Maintenance of high performance formation control is important for low Earth orbit (LEO) formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear and important perturbations affecting the formation configuration,such as J 2 and atmospheric drag,are analyzed as disturbances.Global navigation satellite system based relative positioning with nonlinear filtering is adopted to provide state information associated with the perturbations.By combining disturbance observer based control with H ∞ state feedback,a composite disturbance attenuation controller is proposed for maintenance of continuous and accurate formation.With consideration of precise control relying on micro thrusters,a composite disturbance attenuation based saturated controller is designed and its stability is proved.Finally,through numerical simulations,we demonstrate that control accuracy is improved after effectively avoiding perturbations and that stabilization can be satisfied using this method.
