This paper gives a structural concept for linear interconnected control systems with multidelays,which is based on equivalence method of lyapunovs frequency area, a sufficient \{criteria\} is obtained for the intercon...This paper gives a structural concept for linear interconnected control systems with multidelays,which is based on equivalence method of lyapunovs frequency area, a sufficient \{criteria\} is obtained for the interconnected stabilization of linear constant control system with multidelays,at the same time,the estimation of bound both time delays and parametric perturbation are given.展开更多
The difficulty to select the best system parameters restricts the engineering application of stochastic resonance （SR）. An adaptive cascade stochastic resonance （ACSR） is proposed in the present study. The propose...The difficulty to select the best system parameters restricts the engineering application of stochastic resonance （SR）. An adaptive cascade stochastic resonance （ACSR） is proposed in the present study. The proposed method introduces correlation theory into SR, and uses correlation coefficient of the input signals and noise as a weight to construct the weighted signal-to-noise ratio （WSNR） index. The influence of high frequency noise is alleviated and the signal-to-noise ratio index used in traditional SR is improved accordingly. The ACSR with WSNR can obtain optimal parameters adaptively. And it is not necessary to predict the exact frequency of the target signal. In addition, through the secondary utilization of noise, ACSR makes the signal output waveforrn smoother and the fluctuation period more obvious. Simulation example and engineering application of gearbox fault diagnosis demonstrate the effectiveness and feasibility of the proposed method.展开更多
X-ray bright points （XBPs） are small-scale brightenings in the solar corona. Their counterparts in the lower atmosphere, how- ever, are poorly investigated. In this paper, we study the counterparts of XBPs in the up...X-ray bright points （XBPs） are small-scale brightenings in the solar corona. Their counterparts in the lower atmosphere, how- ever, are poorly investigated. In this paper, we study the counterparts of XBPs in the upper chromosphere where the Hot line center is formed. The XBPs were observed by the X-ray Telescope （XRT） aboard the Hinode spacecraft during the observing plan （HOP0124） in August 2009, coordinated with the Solar Magnetic Activity Research Telescope （SMART） in the Kwasan and Hida Observatory, Kyoto University. It is found that there are 77 Hot brightenings in the same field of view of XRT, and among 57 XBPs, 29 have counterparts in the Hot channel. We found three types of relationship： Types a, b and c, correspond- ing to XBPs appearing first, Hot brightenings occurring first and no respective correspondence between them. Most of the strong XBPs belong to Type a. The Hot counterparts generally have double-kernel structures associated with magnetic bipoles and are cospatial with the footpoints of the XBP loops. The average lag time is -3 minutes. This implies that for Type a the heating, presumably through magnetic reconnection, occurs first in the solar upper atmosphere and then goes downwards along the small-scale magnetic loops that comprise the XBPs. In this case, the thermal conduction plays a dominant role over the non-thermal heating. Only a few events belong to Type b, which could happen when magnetic reconnection occurs in the chromosphere and produces an upward jet which heats the upper atmosphere and causes the XBP. About half of the XBPs belong to Type c. Generally they have weak emission in SXR. About 62% Hot brightenings have no corresponding XBPs. Most of them are weak and have single structures.展开更多
文摘This paper gives a structural concept for linear interconnected control systems with multidelays,which is based on equivalence method of lyapunovs frequency area, a sufficient \{criteria\} is obtained for the interconnected stabilization of linear constant control system with multidelays,at the same time,the estimation of bound both time delays and parametric perturbation are given.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2011CB706805)the National Natural Science Foundation of China (Grant No. 51035007)
文摘The difficulty to select the best system parameters restricts the engineering application of stochastic resonance （SR）. An adaptive cascade stochastic resonance （ACSR） is proposed in the present study. The proposed method introduces correlation theory into SR, and uses correlation coefficient of the input signals and noise as a weight to construct the weighted signal-to-noise ratio （WSNR） index. The influence of high frequency noise is alleviated and the signal-to-noise ratio index used in traditional SR is improved accordingly. The ACSR with WSNR can obtain optimal parameters adaptively. And it is not necessary to predict the exact frequency of the target signal. In addition, through the secondary utilization of noise, ACSR makes the signal output waveforrn smoother and the fluctuation period more obvious. Simulation example and engineering application of gearbox fault diagnosis demonstrate the effectiveness and feasibility of the proposed method.
基金supported by the National Basic Research Program of China (Grant No.2011CB811402)the National Natural Science Foundation of China (Grant Nos.10878002,10610099,10933003,10673004,10073005,10403003,and 11025314)
文摘X-ray bright points （XBPs） are small-scale brightenings in the solar corona. Their counterparts in the lower atmosphere, how- ever, are poorly investigated. In this paper, we study the counterparts of XBPs in the upper chromosphere where the Hot line center is formed. The XBPs were observed by the X-ray Telescope （XRT） aboard the Hinode spacecraft during the observing plan （HOP0124） in August 2009, coordinated with the Solar Magnetic Activity Research Telescope （SMART） in the Kwasan and Hida Observatory, Kyoto University. It is found that there are 77 Hot brightenings in the same field of view of XRT, and among 57 XBPs, 29 have counterparts in the Hot channel. We found three types of relationship： Types a, b and c, correspond- ing to XBPs appearing first, Hot brightenings occurring first and no respective correspondence between them. Most of the strong XBPs belong to Type a. The Hot counterparts generally have double-kernel structures associated with magnetic bipoles and are cospatial with the footpoints of the XBP loops. The average lag time is -3 minutes. This implies that for Type a the heating, presumably through magnetic reconnection, occurs first in the solar upper atmosphere and then goes downwards along the small-scale magnetic loops that comprise the XBPs. In this case, the thermal conduction plays a dominant role over the non-thermal heating. Only a few events belong to Type b, which could happen when magnetic reconnection occurs in the chromosphere and produces an upward jet which heats the upper atmosphere and causes the XBP. About half of the XBPs belong to Type c. Generally they have weak emission in SXR. About 62% Hot brightenings have no corresponding XBPs. Most of them are weak and have single structures.
