随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所...随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所需的各种网络条件,例如:在时变信道的环境下,保证线性系统可镇定性所需的最低编码率;在间断观测的环境下,保证卡尔曼滤波器稳定性的临界丢包条件;在时不变连接图的环境下,达到线性多自主体系统趋同性所需的网络拓扑结构;在通信资源有限的情况下,基于事件驱动的采样与控制方法等.展开更多
We analyzed 360 permanent and campaign GPS data from 1999 to 2017 in the southern Sichuan-Yunan block, and obtained crustal horizontal deformation in this region.Then, we derived the strain rate using a multi-scale sp...We analyzed 360 permanent and campaign GPS data from 1999 to 2017 in the southern Sichuan-Yunan block, and obtained crustal horizontal deformation in this region.Then, we derived the strain rate using a multi-scale spherical wavelet method.Results reveal a complex pattern of tectonic movement in the southern Sichuan-Yunnan block.Compared to the stable Eurasian plate, the maximum rate of the horizontal deformation in the southern Sichuan-Yunnan block is approximately 22 mm/a.The Xiaojiang fault shows a significantly lower deformation—a left-lateral strike-slip movement of 9.5 mm/a.The Honghe fault clearly shows a complex segmental deformation from the north to south.The northern Honghe fault shows 4.3 mm/a right strike-slip with 6.7 mm/a extension; the southern Honghe fault shows 1.9 mm/a right strike-slip with 1.9 mm/a extension; the junction zone in the Honghe and Lijiang–Xiaojinhe faults shows an obvious clockwise-rotation deformation.The strain calculation results reveal that the maximum shear-strain rate in this region reaches 70 nstrain/a, concentrated around the Xiaojiang fault and at the junction of the Honghe and Lijiang–Xiaojinhe faults.We note that most of the earthquakes with magnitudes of 4 and above that occurred in this region were within the high shear strain-rate zones and the strain rate gradient boundary zone, which indicates that the magnitude of strain accumulation is closely related to the seismic activities.Comparison of the fast shear-wave polarization direction of the upper-crust with the upper-mantle anisotropy and the direction of the surface principal compressive strain rate obtained from the inversion of the GPS data reveals that the direction of the surface principal compressive strain is basically consistent with the fast shear-wave polarization direction of the upper crust anisotropy, but different from the polarization direction of the upper mantle.Our results support the hypothesis that the principal elements of the deformation mechanism in the southern Sichuan-Yunnan block 展开更多
文摘随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所需的各种网络条件,例如:在时变信道的环境下,保证线性系统可镇定性所需的最低编码率;在间断观测的环境下,保证卡尔曼滤波器稳定性的临界丢包条件;在时不变连接图的环境下,达到线性多自主体系统趋同性所需的网络拓扑结构;在通信资源有限的情况下,基于事件驱动的采样与控制方法等.
基金supported by the National Natural Science Foundation of China (Project 41730212)the Basic Research Project of the Institute of Earthquake Forecasting, China Earthquake Administration (Grant No.2017IES0102, 2016IES0201)
文摘We analyzed 360 permanent and campaign GPS data from 1999 to 2017 in the southern Sichuan-Yunan block, and obtained crustal horizontal deformation in this region.Then, we derived the strain rate using a multi-scale spherical wavelet method.Results reveal a complex pattern of tectonic movement in the southern Sichuan-Yunnan block.Compared to the stable Eurasian plate, the maximum rate of the horizontal deformation in the southern Sichuan-Yunnan block is approximately 22 mm/a.The Xiaojiang fault shows a significantly lower deformation—a left-lateral strike-slip movement of 9.5 mm/a.The Honghe fault clearly shows a complex segmental deformation from the north to south.The northern Honghe fault shows 4.3 mm/a right strike-slip with 6.7 mm/a extension; the southern Honghe fault shows 1.9 mm/a right strike-slip with 1.9 mm/a extension; the junction zone in the Honghe and Lijiang–Xiaojinhe faults shows an obvious clockwise-rotation deformation.The strain calculation results reveal that the maximum shear-strain rate in this region reaches 70 nstrain/a, concentrated around the Xiaojiang fault and at the junction of the Honghe and Lijiang–Xiaojinhe faults.We note that most of the earthquakes with magnitudes of 4 and above that occurred in this region were within the high shear strain-rate zones and the strain rate gradient boundary zone, which indicates that the magnitude of strain accumulation is closely related to the seismic activities.Comparison of the fast shear-wave polarization direction of the upper-crust with the upper-mantle anisotropy and the direction of the surface principal compressive strain rate obtained from the inversion of the GPS data reveals that the direction of the surface principal compressive strain is basically consistent with the fast shear-wave polarization direction of the upper crust anisotropy, but different from the polarization direction of the upper mantle.Our results support the hypothesis that the principal elements of the deformation mechanism in the southern Sichuan-Yunnan block
