Q. Zong - Academia.edu (original) (raw)
Papers by Q. Zong
49th IEEE Conference on Decision and Control (CDC), 2010
ABSTRACT An Integral Sliding Mode approach to hierarchical control of interconnected systems with... more ABSTRACT An Integral Sliding Mode approach to hierarchical control of interconnected systems with uncertainties arising from unknown interconnection states and unknown parametric variation is proposed. The work is based on a recent study using constrained LQR showing that a two-level hierarchical control system with global coordination control provides a suitable architecture for control of uncertain interconnected systems, in which the control coordinator seeks to balance the effects of the interaction uncertainties. The new method is viewed as an extension to the constrained LQR approach and a nonlinear tutorial example problem is used to illustrate the comparison.
Journal of Geophysical Research: Space Physics, 2013
ABSTRACT [1] In this study, we apply superposed epoch analysis to the 1.5–6.0 MeV electron flux d... more ABSTRACT [1] In this study, we apply superposed epoch analysis to the 1.5–6.0 MeV electron flux dropout events observed on Solar, Anomalous, Magnetospheric Particle Explorer satellite for 110 magnetic storms related to coronal mass ejections (CMEs) associated with interplanetary shocks during 1998–2003, which can help to study one of the scientific objectives of the recently launched Van Allen Probe—to determine and quantify the mechanisms of the losses in the outer radiation belt. Results obtained in this paper show that the impact of high solar wind dynamic pressure (Pdy) on the magnetosphere would lead to much larger electron flux dropout than low dynamic pressure. Furthermore, it is shown that southward interplanetary magnetic field (IMF) condition can result in more significant dropout compared with northward IMF condition. In addition, the largest local dropout is caused by high Pdy with northward IMF at L∼5.1. Dropouts under high Pdy and southward IMF conditions are the largest, whereas dropouts under low Pdy and northward IMF conditions are the smallest. Our study tackles the problem of quantifying the dropouts of electrons by calculating the radiation belt content index and finding the spatial distribution of dropout and the location of maximum dropout. Another finding is that Pdy and IMF affect the dropouts in CME-driven storms. These new findings provide insight into which mechanisms play a more important role in different dropout events.
Journal of Geophysical Research: Space Physics, 2013
ABSTRACT [1] We have identified eight events with double-belt structure in the outer radiation be... more ABSTRACT [1] We have identified eight events with double-belt structure in the outer radiation belt from 110 coronal mass ejection (CME) driven magnetic storms and 223 corotating interaction regions (CIR) driven storms during 1994 to 2003 based on the SAMPEX data sets. Among them, three cases are related to CME-driven magnetic storms and five cases are related CIR-driven storms. All double-belt structure events in the outer radiation belt are found during the recovery phase of a magnetic storm for both CME- and CIR-related events—they usually start to form within 3–4 days after the onset of the magnetic storm. The preconditions needed to form a double-belt structure, for all the CME-related events, are found to be high solar wind dynamic pressure (Pdy) and southward interplanetary magnetic field Bz; nevertheless, for the CIR-related events, they are found to be associated with high-speed stream with southward interplanetary magnetic field, which is enhanced by a suitably orientated By component.It is further found that the flux distributions of the double-belt structure can be fitted well with a simply exponential decay function of L∗. Based on the radiation belt content index, the proportion of the total number of 1.5–6.0 MeV electrons inside the position of maximum fluxes to that outside the maximum fluxes keeps rising during the double-belt period, which implies that the acceleration mainly occurs at regions inside the location of maximum fluxes. We suggest that the plasmapause and the strong wave-particle interactions with VLF and ULF waves near it play an important role in the development of the double-belt structures.
Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, 2014
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2014
On the low-latitude dayside magnetopause, the magnetic field signatures of FTEs, identified from ... more On the low-latitude dayside magnetopause, the magnetic field signatures of FTEs, identified from bipolar variations in the normal components, appear to vary with distance from the magnetopause. If spacecraft takes a trajectory which remains in the magnetosheath and just grazes the sheath-side of the moving FTE structures, it will register a peak in the field magnitude typically accompanied by a
ABSTRACT We present a case study of ionospheric and magnetospheric response to a prolonged interv... more ABSTRACT We present a case study of ionospheric and magnetospheric response to a prolonged interval of strongly northward IMF along with enhanced solar wind dynamic pressure on November 9, 2004. Comprehensive space and ground based observations are examined to investigate global electrodynamic properties of the ionosphere and magnetosphere under northward IMF conditions, including the Cluster satellites located near the high-altitude southern cusp region, the low-altitude DMSP and Fast spacecraft, and ground radar network and magnetometer chains. Global patterns of high-latitude ionospheric convection obtained from the assimilative mapping of ionospheric electrodynamics (AMIE) procedure based on various ground and low-altitude spacecraft measurements show the formation of reserved ionospheric convection in both northern and southern hemispheres simultaneously for nearly 2 hours. Global MHD simulations are also carried out to investigate the physical processes involved in the solar wind-magnetosphere-ionosphere interaction, particularly, the reconnection configuration near the magnetopause, the transport of mass and energy, and the coupling between the magnetosphere and the ionosphere during northward IMF. Cluster observations indicate that multiple magnetopause crossings had been encountered by the spacecraft due to variations in the solar wind dynamic pressure, and the plasma characteristics are consistent with magnetic reconnection taking place tailward of the spacecraft location.
Advances in Space Research, 2005
The Cluster constellation of spacecraft has returned substantial new data on particle and field v... more The Cluster constellation of spacecraft has returned substantial new data on particle and field variations in the near-and midmagnetotail regions of EarthÕs magnetosphere. Using the Research with Adaptive Particle Imaging Detectors (RAPID) system onboard the four Cluster vehicles, we have identified substorm-related energetic (E > 20 keV) electron enhancement events during the period March 2001 through October 2001 in the geocentric radial range of 4-19 Earth radii. We have used concurrent data from other Cluster instruments as well as from the POLAR, IMAGE, FAST, GPS, and geostationary orbit spacecraft in order to understand particle injection and transport phenomena throughout this key region of the magnetotail. Electron enhancements in the plasma sheet at intermediate radial distances have been studied in a global substorm context. A particularly well-observed substorm case occurred on August 27, 2001 when Cluster was almost exactly in the midnight meridian. We find evidence that Cluster was very near the near-Earth substorm neutral line and that magnetic reconnection began some seven minutes prior to the substorm auroral brightening of the expansive phase onset. We also study in some detail the recovery phase of the substorm and the associated expansion of the plasma sheet over the 4-satellite Cluster constellation.
Université Paul Sabatier - Toulouse III.
Astrophysics and Space Science, 2014
ABSTRACT We report the multi-satellite (LANL, GOES-10 and Cluster) observation data of electron f... more ABSTRACT We report the multi-satellite (LANL, GOES-10 and Cluster) observation data of electron flux evolutions and chorus wave excitation in the radiation belt during the geomagnetic storm and substorm from 10 to 14 January, 2002. The seed (50–225 keV) electron flux increased 50 times in five hours during the storm main phase, and the relativistic (>0.6 MeV) electron flux increased about 60 times at night side during the recovery phase. In the meanwhile, the Cluster satellites detected intense chorus waves (the wave power up to ∼10−3 nT2 Hz−1) at MLT≈3 when passing through the outer radiation belt. Using a Gaussian fit to the observed chorus spectra, we calculate the drift-averaged diffusion coefficients and then solve a 2-D Fokker-Planck diffusion equation. We simulate the energetic electron flux evolutions driven by chorus waves in two cases: with and without seed electron injections. We show that the energetic electron flux increases 79 times in three days with injection, comparable to the observation. However, the flux increases only 3 times in three days without injection, far below the observation. The current results suggest that the injected seed electrons and chorus waves play important roles in the buildup of the radiation belt electrons.
Chinese Science Bulletin, 2013
A flapping wave was observed by THEMIS-B (P1) and THEMIS-C (P2) probes on the dawn side of the ma... more A flapping wave was observed by THEMIS-B (P1) and THEMIS-C (P2) probes on the dawn side of the magnetotail, while the solar wind was generally stable. The magnetic activity was quite weak, suggesting that this flapping wave was generated by an internal instability, which normally occurs during magnetic quiet times. Our analysis shows that the flapping wave was propagating downward with a tail-aligned scale of at least 3.7 R E and did not show much change in shape during its propagation from P1 to P2. Correlation analysis employed to estimate the time lag between the corresponding half waveforms of P1 and P2 shows that the propagating velocities along the current sheet normal directions were close to each other in the beginning, but increased linearly later on. The average wavelength of the flapping wave is approximately 4 R E . Theoretical analysis suggests that the ballooning type wave model may not be the mechanism for the observed flapping wave, but that the magnetic double-gradient instability model is a more plausible candidate.
The Astrophysical Journal, 2015
ABSTRACT The wave-particle interaction processes occurring in the solar wind provide crucial info... more ABSTRACT The wave-particle interaction processes occurring in the solar wind provide crucial information to understand the wave dissipation and simultaneous particle heating in plasma turbulence. One requires observations of both wave fluctuations and particle kinetics near the dissipation range, which have, however, not yet been analyzed simultaneously. Here we show new evidence of wave-particle interactions by combining the diagnosis of wave modes with the analysis of particle kinetics on the basis of measurements from the WIND spacecraft with a high cadence of about 3 s. Solar wind protons appear to be highly dynamic in their velocity distribution consisting of varying anisotropic core and beam components. The basic scenario of solar wind proton heating through wave-particle interaction is suggested to be the following. Left-handed cyclotron resonance occurs continuously, and is evident from the observed proton core velocity distribution and the concurrent quasi-parallel left-handed Alfvén cyclotron waves. Landau and right-handed cyclotron resonances are persistent and indicated by the observed drifting anisotropic beam and the simultaneous quasi-perpendicular right-handed kinetic Alfvén waves in a general sense. The persistence of non-gyrotropic proton distributions may cast new light on the nature of the interaction between particles and waves near and beyond the proton gyro-frequency.
Journal of Geophysical Research: Space Physics, 2015
49th IEEE Conference on Decision and Control (CDC), 2010
ABSTRACT An Integral Sliding Mode approach to hierarchical control of interconnected systems with... more ABSTRACT An Integral Sliding Mode approach to hierarchical control of interconnected systems with uncertainties arising from unknown interconnection states and unknown parametric variation is proposed. The work is based on a recent study using constrained LQR showing that a two-level hierarchical control system with global coordination control provides a suitable architecture for control of uncertain interconnected systems, in which the control coordinator seeks to balance the effects of the interaction uncertainties. The new method is viewed as an extension to the constrained LQR approach and a nonlinear tutorial example problem is used to illustrate the comparison.
Journal of Geophysical Research: Space Physics, 2013
ABSTRACT [1] In this study, we apply superposed epoch analysis to the 1.5–6.0 MeV electron flux d... more ABSTRACT [1] In this study, we apply superposed epoch analysis to the 1.5–6.0 MeV electron flux dropout events observed on Solar, Anomalous, Magnetospheric Particle Explorer satellite for 110 magnetic storms related to coronal mass ejections (CMEs) associated with interplanetary shocks during 1998–2003, which can help to study one of the scientific objectives of the recently launched Van Allen Probe—to determine and quantify the mechanisms of the losses in the outer radiation belt. Results obtained in this paper show that the impact of high solar wind dynamic pressure (Pdy) on the magnetosphere would lead to much larger electron flux dropout than low dynamic pressure. Furthermore, it is shown that southward interplanetary magnetic field (IMF) condition can result in more significant dropout compared with northward IMF condition. In addition, the largest local dropout is caused by high Pdy with northward IMF at L∼5.1. Dropouts under high Pdy and southward IMF conditions are the largest, whereas dropouts under low Pdy and northward IMF conditions are the smallest. Our study tackles the problem of quantifying the dropouts of electrons by calculating the radiation belt content index and finding the spatial distribution of dropout and the location of maximum dropout. Another finding is that Pdy and IMF affect the dropouts in CME-driven storms. These new findings provide insight into which mechanisms play a more important role in different dropout events.
Journal of Geophysical Research: Space Physics, 2013
ABSTRACT [1] We have identified eight events with double-belt structure in the outer radiation be... more ABSTRACT [1] We have identified eight events with double-belt structure in the outer radiation belt from 110 coronal mass ejection (CME) driven magnetic storms and 223 corotating interaction regions (CIR) driven storms during 1994 to 2003 based on the SAMPEX data sets. Among them, three cases are related to CME-driven magnetic storms and five cases are related CIR-driven storms. All double-belt structure events in the outer radiation belt are found during the recovery phase of a magnetic storm for both CME- and CIR-related events—they usually start to form within 3–4 days after the onset of the magnetic storm. The preconditions needed to form a double-belt structure, for all the CME-related events, are found to be high solar wind dynamic pressure (Pdy) and southward interplanetary magnetic field Bz; nevertheless, for the CIR-related events, they are found to be associated with high-speed stream with southward interplanetary magnetic field, which is enhanced by a suitably orientated By component.It is further found that the flux distributions of the double-belt structure can be fitted well with a simply exponential decay function of L∗. Based on the radiation belt content index, the proportion of the total number of 1.5–6.0 MeV electrons inside the position of maximum fluxes to that outside the maximum fluxes keeps rising during the double-belt period, which implies that the acceleration mainly occurs at regions inside the location of maximum fluxes. We suggest that the plasmapause and the strong wave-particle interactions with VLF and ULF waves near it play an important role in the development of the double-belt structures.
Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, 2014
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2014
On the low-latitude dayside magnetopause, the magnetic field signatures of FTEs, identified from ... more On the low-latitude dayside magnetopause, the magnetic field signatures of FTEs, identified from bipolar variations in the normal components, appear to vary with distance from the magnetopause. If spacecraft takes a trajectory which remains in the magnetosheath and just grazes the sheath-side of the moving FTE structures, it will register a peak in the field magnitude typically accompanied by a
ABSTRACT We present a case study of ionospheric and magnetospheric response to a prolonged interv... more ABSTRACT We present a case study of ionospheric and magnetospheric response to a prolonged interval of strongly northward IMF along with enhanced solar wind dynamic pressure on November 9, 2004. Comprehensive space and ground based observations are examined to investigate global electrodynamic properties of the ionosphere and magnetosphere under northward IMF conditions, including the Cluster satellites located near the high-altitude southern cusp region, the low-altitude DMSP and Fast spacecraft, and ground radar network and magnetometer chains. Global patterns of high-latitude ionospheric convection obtained from the assimilative mapping of ionospheric electrodynamics (AMIE) procedure based on various ground and low-altitude spacecraft measurements show the formation of reserved ionospheric convection in both northern and southern hemispheres simultaneously for nearly 2 hours. Global MHD simulations are also carried out to investigate the physical processes involved in the solar wind-magnetosphere-ionosphere interaction, particularly, the reconnection configuration near the magnetopause, the transport of mass and energy, and the coupling between the magnetosphere and the ionosphere during northward IMF. Cluster observations indicate that multiple magnetopause crossings had been encountered by the spacecraft due to variations in the solar wind dynamic pressure, and the plasma characteristics are consistent with magnetic reconnection taking place tailward of the spacecraft location.
Advances in Space Research, 2005
The Cluster constellation of spacecraft has returned substantial new data on particle and field v... more The Cluster constellation of spacecraft has returned substantial new data on particle and field variations in the near-and midmagnetotail regions of EarthÕs magnetosphere. Using the Research with Adaptive Particle Imaging Detectors (RAPID) system onboard the four Cluster vehicles, we have identified substorm-related energetic (E > 20 keV) electron enhancement events during the period March 2001 through October 2001 in the geocentric radial range of 4-19 Earth radii. We have used concurrent data from other Cluster instruments as well as from the POLAR, IMAGE, FAST, GPS, and geostationary orbit spacecraft in order to understand particle injection and transport phenomena throughout this key region of the magnetotail. Electron enhancements in the plasma sheet at intermediate radial distances have been studied in a global substorm context. A particularly well-observed substorm case occurred on August 27, 2001 when Cluster was almost exactly in the midnight meridian. We find evidence that Cluster was very near the near-Earth substorm neutral line and that magnetic reconnection began some seven minutes prior to the substorm auroral brightening of the expansive phase onset. We also study in some detail the recovery phase of the substorm and the associated expansion of the plasma sheet over the 4-satellite Cluster constellation.
Université Paul Sabatier - Toulouse III.
Astrophysics and Space Science, 2014
ABSTRACT We report the multi-satellite (LANL, GOES-10 and Cluster) observation data of electron f... more ABSTRACT We report the multi-satellite (LANL, GOES-10 and Cluster) observation data of electron flux evolutions and chorus wave excitation in the radiation belt during the geomagnetic storm and substorm from 10 to 14 January, 2002. The seed (50–225 keV) electron flux increased 50 times in five hours during the storm main phase, and the relativistic (>0.6 MeV) electron flux increased about 60 times at night side during the recovery phase. In the meanwhile, the Cluster satellites detected intense chorus waves (the wave power up to ∼10−3 nT2 Hz−1) at MLT≈3 when passing through the outer radiation belt. Using a Gaussian fit to the observed chorus spectra, we calculate the drift-averaged diffusion coefficients and then solve a 2-D Fokker-Planck diffusion equation. We simulate the energetic electron flux evolutions driven by chorus waves in two cases: with and without seed electron injections. We show that the energetic electron flux increases 79 times in three days with injection, comparable to the observation. However, the flux increases only 3 times in three days without injection, far below the observation. The current results suggest that the injected seed electrons and chorus waves play important roles in the buildup of the radiation belt electrons.
Chinese Science Bulletin, 2013
A flapping wave was observed by THEMIS-B (P1) and THEMIS-C (P2) probes on the dawn side of the ma... more A flapping wave was observed by THEMIS-B (P1) and THEMIS-C (P2) probes on the dawn side of the magnetotail, while the solar wind was generally stable. The magnetic activity was quite weak, suggesting that this flapping wave was generated by an internal instability, which normally occurs during magnetic quiet times. Our analysis shows that the flapping wave was propagating downward with a tail-aligned scale of at least 3.7 R E and did not show much change in shape during its propagation from P1 to P2. Correlation analysis employed to estimate the time lag between the corresponding half waveforms of P1 and P2 shows that the propagating velocities along the current sheet normal directions were close to each other in the beginning, but increased linearly later on. The average wavelength of the flapping wave is approximately 4 R E . Theoretical analysis suggests that the ballooning type wave model may not be the mechanism for the observed flapping wave, but that the magnetic double-gradient instability model is a more plausible candidate.
The Astrophysical Journal, 2015
ABSTRACT The wave-particle interaction processes occurring in the solar wind provide crucial info... more ABSTRACT The wave-particle interaction processes occurring in the solar wind provide crucial information to understand the wave dissipation and simultaneous particle heating in plasma turbulence. One requires observations of both wave fluctuations and particle kinetics near the dissipation range, which have, however, not yet been analyzed simultaneously. Here we show new evidence of wave-particle interactions by combining the diagnosis of wave modes with the analysis of particle kinetics on the basis of measurements from the WIND spacecraft with a high cadence of about 3 s. Solar wind protons appear to be highly dynamic in their velocity distribution consisting of varying anisotropic core and beam components. The basic scenario of solar wind proton heating through wave-particle interaction is suggested to be the following. Left-handed cyclotron resonance occurs continuously, and is evident from the observed proton core velocity distribution and the concurrent quasi-parallel left-handed Alfvén cyclotron waves. Landau and right-handed cyclotron resonances are persistent and indicated by the observed drifting anisotropic beam and the simultaneous quasi-perpendicular right-handed kinetic Alfvén waves in a general sense. The persistence of non-gyrotropic proton distributions may cast new light on the nature of the interaction between particles and waves near and beyond the proton gyro-frequency.
Journal of Geophysical Research: Space Physics, 2015