A Sandwich Control System with Dual Stochastic Impulses

Dear editor,Along with the progress of science and technology and the development of social civilization,control system brings an increasingly significant function in daily life.The application field of control system is very wide,for instance,in mobile technology[1],artificial earth satellite[2],pest control[3],etc.Ribeiro[4]first put forward the concept of random pulse in 1967.At present,impulsive control is used in networked control[5],secure communication[6],etc.In the 21st century,the impulsive control has been used in synchronization of coupled system,intelligent fault identification,image encryption.

Seismicity changes and numerical simulation of coseismic deformation following the 2022 M_(s)6.8 Luding earthquake in Sichuan,China

The Xianshuihe fault is a major tectonic boundary between the Sichuan-Yunnan rhombic and Bayanhar blocks in Southwest China.With an average left-lateral strike-slip movement of 10–15 mm/yr,it is a fast-moving strike-slip continental fault.On September 5,2022,the Ms6.8 Luding earthquake occurred along the Moxi segment of the Xianshuihe fault,reaching a maximum intensity of IX and resulting in a significant number of casualties and severe property damage.This earthquake broke the long-standing seismic quiescence of the Xianshuihe fault,which lasted for more than 40 years,and was followed by a significant number of aftershocks.An outstanding question is how the behavior of the Xianshuihe fault and major earthquakes changed following this mainshock.In this study,we examined the changes in regional seismicity following the Luding earthquake and identified the potential for future strong earthquakes along the Xianshuihe fault.We used a finite element numerical method to simulate the environment of the seismogenic fault and its adjacent areas.In addition,we used the coseismic slip model of the Luding earthquake with the split-node method to calculate how the stress and strain fields in the surrounding area were affected by the2022 mainshock.Coulomb stress changes were resolved in the main faults,and the seismicity of adjacent faults was analyzed in conjunction with the observed seismic data.The results indicate that regional tectonic movement primarily occurred to the southeast along the Moxi segment.The stress field is approximately north-south in tension and east-west in compression.Variation in the stress field in the epicentral region of the Luding earthquake exceeded 1 MPa.The maximum displacement of the coseismic deformation field was concentrated between Moxi town and Tuanjie village,and the Coulomb stress of the fault zone in this region experienced the largest decrease.However,the b-value of the Gutenberg-Richter magnitude-frequency relationship at the epicenter and the surrounding area exhibited an abnormal pattern of decrease-decrease-increase,indicating that the regional stress may not be fully released.This earthquake increased the Coulomb stress in other segments of the Xianshuihe,Anninghe,and Daliangshan faults,whereas the Coulomb stress in the Longmenshan and Xiaojinhe fault zones decreased.In addition,it triggered a series of normal-fault,moderate-sized earthquakes in nearby areas.The Dagangshan reservoir,located~20 km from the epicenter of the Luding earthquake,received an increase of~5.3 MPa in the tensile stress along the NWW-SEE direction.The Xiluodu Reservoir,located approximately 225 km from the epicenter,was less affected by this earthquake,and the seismic activity near the reservoir remained relatively unchanged.In this study,post-earthquake seismicity in the vicinity of the Ms6.8 Luding earthquake was analyzed and predicted by numerical simulation,providing a scientific basis for earthquake prediction and disaster reduction.

Finite element simulation of deformation and stress changes of Kalpin-Kemin fault system in the Southwest Tianshan Orogenic Belt

Under the shadow of the far-field effect of the India-Eurasia collision,the Tianshan orogenic belt underwent tectonic re-activation in the Cenozoic,accompanied by strong tectonic deformation and frequent large earthquakes.Bounded by two rigid cratonic blocks located in its north and south,a series of marginal foreland fold-and-thrust belts are developed within the Tianshan orogenic belt and continue to develop to the bilateral pull-apart basins.Meanwhile,the faults in the orogenic belt are reactivated.The deformation caused by thrust-related structure accounts for larger than 50%of the total convergence of the Tianshan Mountains,which results in the most active structure with large earthquakes in the Tianshan area.Therefore,it is of great significance to study the dynamic process of the newly generated and reactivated thrust-nappe structures in Tianshan orogen via numerical modeling.This paper selects a classical cross-section profile in the western segment of the Southwest Tianshan Mountains,which contains the Kalpin-Maidan-Nalati-Kemin fault system from the south to the north.We attempt to establish a two-dimensional plane strain,viscoelastic finite element model,by treating the regional faults as a whole fault system and considering the topography,fault geometry,and GPS data.The displacement and stress fields of the model are retrieved,the short-term cumulative deformation field of the overall fault system is analyzed,and the rate of Coulomb failure stress change of each fault is also considered.The results show that the deformation is concentrated in the middle and southern parts of the Southwest Tianshan Mountains.In contrast,the deformation of the Kemin fault in the north is relatively small.According to the Coulomb failure stress changes of these four faults and the historical earthquake catalog,the potential seismicity of each fault is qualitatively analyzed.Our preliminary results suggest that the possibility of large earthquake occurrence is higher in the Kalpin fault,Maidan fault,and Nalati fault but lower in the Kemin fault in the near future。