Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain...Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.展开更多
Dear Editor,This letter deals with the stabilization of a resilient model predictive control(MPC)algorithm with a dynamic event-triggered mechanism subject to Denial-of-Service(Do S)attacks.Different from previous wor...Dear Editor,This letter deals with the stabilization of a resilient model predictive control(MPC)algorithm with a dynamic event-triggered mechanism subject to Denial-of-Service(Do S)attacks.Different from previous works,this letter is based on the designed threshold function to dynamically trigger and gives the upper bound conditions for intersampling intervals with attack and attack-free scenarios to converge.展开更多
Starting from vorticity equation, the triggering mechanism and amplitude decay of shear waves in the ocean are discussed in this paper. The theoretical analysis indicates that by the action of stripped external force ...Starting from vorticity equation, the triggering mechanism and amplitude decay of shear waves in the ocean are discussed in this paper. The theoretical analysis indicates that by the action of stripped external force (for examples, the sudden setting of stripped wind, moving stripped wind, etc. ), shear waves can be triggered. This is qualitatively consistent with satellite observations. The amplitude decay process of shear waves by the action of side friction is also discussed in the paper. The theoretical model is quantitatively consistent with satellite observations.展开更多
Dear editor,Recently,researchers have obtained many new results about the multi-agent systems(MASs)[1]-[3].In[1],the fixed-time cooperative control(FTCC)algorithm of linear MASs with matched disturbances was proposed....Dear editor,Recently,researchers have obtained many new results about the multi-agent systems(MASs)[1]-[3].In[1],the fixed-time cooperative control(FTCC)algorithm of linear MASs with matched disturbances was proposed.The nonholonomic chained-form dynamics case was considered in[2].In[3],the output tracking problem with data packet dropout was solved for high-order MASs.Moreover,delay frequently occurs because of the non-ideal data transmission[4],and the corresponding FTCC algorithm of MASs with delay was given in[5].展开更多
There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Base...There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Based on the theory of a 3D viscous-spring artificial boundary,this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program,which was applied to an ABAQUS finite element model.Based on near-fault and far-field groundmotions obtained fromtheNGA-WEST2 database,the dynamic responses of a utility tunnel and its internal pipeline in different inputmechanisms of near-fault and far-field groundmotions were compared according to bidirectional input and tridirectional input,respectively.Generally,the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion,and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel.In addition,the joint dislocation of the upper and lower three-way joints of the pipeline in the branch systemunder the seismic action led to local stress concentrations.In general,the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline fromdamage during the rare earthquake.展开更多
Earthquakes triggered by dynamic disturbances have been confirmed by numerous observations and experiments.In the past several decades,earthquake triggering has attracted increasing attention of scholars in relation t...Earthquakes triggered by dynamic disturbances have been confirmed by numerous observations and experiments.In the past several decades,earthquake triggering has attracted increasing attention of scholars in relation to exploring the mechanism of earthquake triggering,earthquake prediction,and the desire to use the mechanism of earthquake triggering to reduce,prevent,or trigger earthquakes.Natural earthquakes and large‐scale explosions are the most common sources of dynamic disturbances that trigger earthquakes.In the past several decades,some models have been developed,including static,dynamic,quasi‐static,and other models.Some reviews have been published,but explosiontriggered seismicity was not included.In recent years,some new results on earthquake triggering have emerged.Therefore,this paper presents a new review to reflect the new results and include the content of explosion‐triggered earthquakes for the reference of scholars in this area.Instead of a complete review of the relevant literature,this paper primarily focuses on the main aspects of dynamic earthquake triggering on a tectonic scale and makes some suggestions on issues that need to be resolved in this area in the future.展开更多
Cells actively modulate mechanobiological circuitry against external perturbations to stabilize whole cell/tissue physiology.The dynamic adaption of cells to mechanical force is critical for cells to perform vital bio...Cells actively modulate mechanobiological circuitry against external perturbations to stabilize whole cell/tissue physiology.The dynamic adaption of cells to mechanical force is critical for cells to perform vital biological functions,from single cell migration to embryonic development.Dysregulation of such dynamics has been associated with pathophysiological conditions in cardiovascular diseases,cancer,aging,and developmental disorders[1].Therefore,a direct understanding of cell’s biomechanical adaptive/maladaptive behaviors and the trigger factors causing the transformation of healthy adaption to maladaptation can help reveal the regulatory role of single cell mechanosensitive dynamics in the progression of various degenerative diseases and aging.However,current efforts for uncovering fundamental associations between disease and cell architecture have been focusing on'static'measurements of biophysical properties,which is limited by the requirement of large sample sizes to obtain statistically significant data.We therefore developed a single and highly integrated platform with mechanical stimulation and fine spatiotemporal sensing functions to probe the single cell mechanical dynamics at subcellular level to determine cell’s mechanophenotypes in healthy and disease conditions.We developed an integrated micromechanical system composed of an’ultrasound tweezer’stimulator[2]and a PDMS micropillar array [3] cellular force sensor to in situ noninvasively probe and monitor single cell mechanical dynamics.Vascular smooth muscle cells(VSMCs)from healthy mouse and mouse with induced abdominal aorta aneurysm(AAA)were used for cell mechanobiological study.An ultrasound transducer(V312-SM,Olympus)was used to generate ultrasound pulses to excite lipid-encapsulated microbubbles(Targeson)binding to cell membrane through an RGD-integrin linkage to apply a transient nanonewton force to VSMCs seeded on the PDMS micropillar array.PDMS micropillar array was fabricated and functionalized as previously described [3] and acts as the mechanical force sensor in our platform.Upon a 1 HZ and 10-second ultrasound stimulation,calcium influx was clearly detected in both healthy and AAA-VSMCs by using the fluo-4 calcium sensor,suggesting the microbubble-integrin-actin cytoskeleton(CSK)linkage can serve as a mechanosensory to sense the ultrasound stimulation.We then examined how healthy and AAA VSMCs would exhibit adaptions to mechanical stimulation at a global cellular scale.After the onset of a 10-second ultrasound stimulation,control and AAA-VSMCs displayed distinct dynamics of CSK tension within 30 mins,in which the CSK tension of healthy VSMCs increased within the reinforcement period(0-5 min)and restored to their ground state with the relaxation period(5-10 min);yet AAA-VSMCs displayed compromised dynamics of such CSK tension upon calcium influx.Quantitative analysis and theoretical modelling revealed the critical roles of myosin motor contraction,F-actin filament polymerization in regulating cell mechanosensitive dynamics in response to a transient mechanical perturbation.The distinct force and CSK dynamics in healthy and AAA conditions indicates that the force-dependent CSK molecular kinetics is a critical factor governing the distinct mechanosensitive dynamics of cells under pathologically dysfunctional conditions.Our results reveal that the mechanical adaptive process of cells to mechanical stimulus can measure the cellular mechanobiological phenotypes featured in both pathologically healthy and diseased context.We demonstrated that an altered mechanobiological phenotype,i.e.AAA-VSMCs with distinct actomyosin-CSK properties potentiates a mechanical maladaptation that reflects progressive accumulation of cellular damage and dysfunction.This may further reveal the pathogenic contexts and their physical mediators featuring biophysical dysregulation in cardiovascular diseases.展开更多
Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequen...Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent after- shocks. The results show that the spatial distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric, which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic and static stresses should be con- sidered other than only either of them when studying aftershock triggering in near field.展开更多
In order to achieve dynamical optimization of mobility load balancing,we analyze the conflict between mobility load balancing and mobility robustness optimization caused by the improper operation of handover parameter...In order to achieve dynamical optimization of mobility load balancing,we analyze the conflict between mobility load balancing and mobility robustness optimization caused by the improper operation of handover parameters.To this end,a method of Handover Parameters Adjustment for Conflict Avoidance(HPACA)is proposed.Considering the movement of users,HPCAC can dynamically adjust handover range to optimize the mobility load balancing.The movement of users is an important factor of handover,which has a dramatic impact on system performance.The numerical evaluation results show the proposed approach outperforms the existing method in terms of throughput,call blocking ratio,load balancing index,radio link failure ratio,ping-pong handover ratio and call dropping ratio.展开更多
This paper briefly reviews basic theory of seismic stress triggering. Recent development on seismic stress triggering has been reviewed in the views of seismic static and dynamic stress triggering, application of visc...This paper briefly reviews basic theory of seismic stress triggering. Recent development on seismic stress triggering has been reviewed in the views of seismic static and dynamic stress triggering, application of viscoelastic model in seismic stress triggering, the relation between earthquake triggering and volcanic eruption or explosion, other explanation of earthquake triggering, etc. And some suggestions for further study on seismic stress triggering in near future are given.展开更多
Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/2...Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/29 in PA,which provides an excellent opportunity to investigate the triggering relationship among these events. We calculate the static Coulomb stress changes of the first five events,and find that the local seismicity after the 2018/12/29 M_(w) 7.0 earthquake is mostly associated with positive Coulomb stress changes,including the 2019/05/31 M_(w) 6.1 event,suggesting a possible triggering relationship. However,we cannot rule out the dynamic triggering mechanism,due to increased microseismicity in both positive and negative stress change regions,and an incomplete local catalog,especially right after the first M_(w) 7.0 mainshock. The dynamic stresses from these M_(w) > 6 events are large enough (from 5 kPa to 3532 kPa) to trigger subsequent events,but a lack of seismicity and waveform evidence does not support delayed dynamic triggering among these events,even the shortest time interval is less than 24 hours. In the past 45 years,the released seismic energy shows certain peaks every 5–10 years. However,earthquakes with M_(w) > 6.0 were relatively infrequent between 2004 and 2018 at PA. Hence,it is possible that several regions are relatively late in their earthquake cycles,which would enhance their susceptibility of being triggered by earthquakes at nearby and regional distances.展开更多
The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support fo...The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support for surrounding rock.In this study,the theoretical solution for the dynamic stress concentration factor(DSCF)of a circular tunnel subjected to cylindrical and plane P-waves was derived using the wave function expansion method.The existing equivalent blast stress wave was optimized and the Ricker wavelet was introduced to represent the seismic stress waves.By combining Fourier transform and Duhamel’s integral,the transient response of the underground tunnel under near-field blasts and far-field earthquakes was determined in both the frequency and time domains.The theoretical results were validated by comparing them with those obtained from numerical simulations using ANSYS LS-DYNA software.Numerical simulations were conducted to further investigate the damage characteristics of the underground tunnel and evaluate the effect of initial stress on structural failure under both types of disturbances.The theoretical and numerical simulation results indicated that the differences in the dynamic response and damage characteristics of the underground tunnel were primarily due to the curvature of the stress waves and transient load waveform.The locations of the maximum DSCF values differed between near-field blasts and far-field earthquakes,whereas the minimum DSCF values occurred at the same positions.Without initial stress,the blast stress waves caused spalling damage to the rock mass on the wave-facing side.Shear failure occurred near the areas with maximum DSCF values,and tensile failure occurred near the areas with minimum DSCF values.In contrast,damage occurred only near the areas with maximum DSCF values under seismic stress waves.Furthermore,the initial stress exacerbated spalling and shear damage while suppressing tensile failure.Hence,the blast stress waves no longer induced tensile failure on the tunnel sidewalls under initial stress.展开更多
The spatiotemporal evolution patterns of complete Coulomb stress changes caused by 1988 Ms7.6 earthquake in Lancang-Gengma, Yunnan, are calculated and studied. And the triggering problems of Ms7.2 Gengma shock occurri...The spatiotemporal evolution patterns of complete Coulomb stress changes caused by 1988 Ms7.6 earthquake in Lancang-Gengma, Yunnan, are calculated and studied. And the triggering problems of Ms7.2 Gengma shock occurring 13 minutes after the main shock and of Ms5.0―6.9 aftershocks within 24 days after the main shock are discussed. The results show that the spatial distribution patterns of complete Coulomb stress changes of the Ms7.6 main shock are strongly asymmetric. The areas of positive dynamic and static Coulomb stress are both coincident well with the strong aftershocks' loca-tions. The Ms7.2 Gengma shock and most of strong aftershocks are subjected to the triggering effect of dynamic and static Coulomb stresses induced by the Ms7.6 Lancang earthquake.展开更多
In view of the three-dimensional dynamic abutment pressure,the influence of the far-field hard stratum(FHS)in deep,thick coal seams is indeterminant.Based on elastic foundation theory,a three-dimensional dynamic predi...In view of the three-dimensional dynamic abutment pressure,the influence of the far-field hard stratum(FHS)in deep,thick coal seams is indeterminant.Based on elastic foundation theory,a three-dimensional dynamic prediction model of the abutment pressure was established.Using this model,the dynamic change in the coal seam abutment pressure caused by the movement of the FHS was studied,and a method for determining the dynamic change range of the abutment pressure was developed.The results of the new prediction model of the abutment pressure are slightly higher than the measured values,with an error of 0.51%,which avoids the shortcomings of the results because the Winkler foundation model results are lower than the measured values and have an error of 9.98%.As time progresses,the abutment pressure and its distribution range are affected by the FHS movement,which has the characteristics of gradually increasing dynamic change until the FHS fractures.The peak value of the abutment pressure increases linearly with time,and the influence range increases with time following a power function with an exponent of less than 1.The influence range of the FHS movement on the abutment pressure ahead of the working face,behind the working face,and along the working face is 10 times,25 times,and 17 times the mining thickness,respectively.According to the actual geological parameters,the dynamic change range of the coal seam abutment pressure was determined by drawing an additional stress curve and by determining the threshold value.These research results are of great significance to the partition optimization of the roadway support design of deep,thick coal seams.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52274075,42122052,52379098)。
文摘Landslides triggered by seismic activity have led to substantial human and economic losses.Nevertheless,the fundamental physical mechanisms underlying the vibration and rupture of rock slopes during earthquakes remain poorly understood.In this study,finite element method-based numerical simulations were conducted based on the rock slope at Dagangshan Hydropower Station in Sichuan province,China.Firstly,systematic analysis in both the time and frequency domains were performed to examine the seismic dynamic characteristics of the slope.Subsequently,the transfer function method and the multiple stepwise linear regression method were employed to clarify the underlying mechanism and determine critical factors influencing the slope instability during earthquakes.Time-domain analysis reveals that rock slope dynamic response exhibits notable elevation,surface,and local amplification effects.Specifically,the Peak Ground Acceleration(PGA)amplification coefficient(MPGA)is significantly higher at elevated locations,near the slope surface and in areas with protrusions.Moreover,the existence of fracture zones and anti-shear galleries minimally influences the dynamic responses but considerably affect the rupture.Specifically,fracture zones exacerbate rupture,while anti-shear galleries mitigate it.Frequency-domain analysis indicates that the dynamic responses of the slope are closely correlated with the degree of slope rupture.As earthquake magnitude increases,the rupture degree of the slope intensifies,and the dominant frequency of the response within the slope decreases,e.g.,its value shifts from 3.63 to 2.75 Hz at measurement point 9near the slope surface.The transfer function of rock slope,calculated under the excitation of wide flat spectrum white noise can reflect the interrelationships between the inherent properties and the rupture degree.Notably,the peak of the transfer function undergoes inversion as the degree of rupture increases.Furthermore,through multiple stepwise linear regression analysis,four key factors influencing the surface dynamic response of the slope were identified:rock strength,slope angle,elevation,and seismic dominant frequency.These findings provide valuable insights into the underlying mechanisms of rock slope dynamic responses triggered by earthquakes,offering essential guidance for understanding and mitigating seismic impacts on rock slopes.
文摘Dear Editor,This letter deals with the stabilization of a resilient model predictive control(MPC)algorithm with a dynamic event-triggered mechanism subject to Denial-of-Service(Do S)attacks.Different from previous works,this letter is based on the designed threshold function to dynamically trigger and gives the upper bound conditions for intersampling intervals with attack and attack-free scenarios to converge.
文摘Starting from vorticity equation, the triggering mechanism and amplitude decay of shear waves in the ocean are discussed in this paper. The theoretical analysis indicates that by the action of stripped external force (for examples, the sudden setting of stripped wind, moving stripped wind, etc. ), shear waves can be triggered. This is qualitatively consistent with satellite observations. The amplitude decay process of shear waves by the action of side friction is also discussed in the paper. The theoretical model is quantitatively consistent with satellite observations.
基金supported in part by the National Natural Science Foundation of China(62103099,61921004)the Natural Science Foundation of Jiangsu Province of China(BK20210214).
文摘Dear editor,Recently,researchers have obtained many new results about the multi-agent systems(MASs)[1]-[3].In[1],the fixed-time cooperative control(FTCC)algorithm of linear MASs with matched disturbances was proposed.The nonholonomic chained-form dynamics case was considered in[2].In[3],the output tracking problem with data packet dropout was solved for high-order MASs.Moreover,delay frequently occurs because of the non-ideal data transmission[4],and the corresponding FTCC algorithm of MASs with delay was given in[5].
基金National Key R&D Program of China under Grants No.2019YFC1509301.
文摘There are few studies on the dynamic-response mechanism of near-fault and far-field ground motions for large underground structures,especially for the branch joint of a utility tunnel(UT)and its internal pipeline.Based on the theory of a 3D viscous-spring artificial boundary,this paper deduced the equivalent nodal force when a P wave and an SV wave were vertically incident at the same time and transformed the ground motion into an equivalent nodal force using a self-developed MATLAB program,which was applied to an ABAQUS finite element model.Based on near-fault and far-field groundmotions obtained fromtheNGA-WEST2 database,the dynamic responses of a utility tunnel and its internal pipeline in different inputmechanisms of near-fault and far-field groundmotions were compared according to bidirectional input and tridirectional input,respectively.Generally,the damage to the utility tunnel caused by the near-fault ground motion was stronger than that caused by the far-field ground motion,and the vertical ground motion of near-fault ground motion aggravated the damage to the utility tunnel.In addition,the joint dislocation of the upper and lower three-way joints of the pipeline in the branch systemunder the seismic action led to local stress concentrations.In general,the branch system of the utility tunnel had good seismic performance to resist the designed earthquake action and protect the internal pipeline fromdamage during the rare earthquake.
基金supported by the National Natural Science Foundation of China(NSFC grants No.12172036,51774018)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT,IRT_17R06)+2 种基金the Russian Foundation for Basic Research,Grant Number 20‐55‐53032Russian State Task number 1021052706247‐7‐1.5.4the Government of Perm Krai,research project No.С‐26/628.
文摘Earthquakes triggered by dynamic disturbances have been confirmed by numerous observations and experiments.In the past several decades,earthquake triggering has attracted increasing attention of scholars in relation to exploring the mechanism of earthquake triggering,earthquake prediction,and the desire to use the mechanism of earthquake triggering to reduce,prevent,or trigger earthquakes.Natural earthquakes and large‐scale explosions are the most common sources of dynamic disturbances that trigger earthquakes.In the past several decades,some models have been developed,including static,dynamic,quasi‐static,and other models.Some reviews have been published,but explosiontriggered seismicity was not included.In recent years,some new results on earthquake triggering have emerged.Therefore,this paper presents a new review to reflect the new results and include the content of explosion‐triggered earthquakes for the reference of scholars in this area.Instead of a complete review of the relevant literature,this paper primarily focuses on the main aspects of dynamic earthquake triggering on a tectonic scale and makes some suggestions on issues that need to be resolved in this area in the future.
基金the financial support from the American Heart Association ( 16SDG31020038)
文摘Cells actively modulate mechanobiological circuitry against external perturbations to stabilize whole cell/tissue physiology.The dynamic adaption of cells to mechanical force is critical for cells to perform vital biological functions,from single cell migration to embryonic development.Dysregulation of such dynamics has been associated with pathophysiological conditions in cardiovascular diseases,cancer,aging,and developmental disorders[1].Therefore,a direct understanding of cell’s biomechanical adaptive/maladaptive behaviors and the trigger factors causing the transformation of healthy adaption to maladaptation can help reveal the regulatory role of single cell mechanosensitive dynamics in the progression of various degenerative diseases and aging.However,current efforts for uncovering fundamental associations between disease and cell architecture have been focusing on'static'measurements of biophysical properties,which is limited by the requirement of large sample sizes to obtain statistically significant data.We therefore developed a single and highly integrated platform with mechanical stimulation and fine spatiotemporal sensing functions to probe the single cell mechanical dynamics at subcellular level to determine cell’s mechanophenotypes in healthy and disease conditions.We developed an integrated micromechanical system composed of an’ultrasound tweezer’stimulator[2]and a PDMS micropillar array [3] cellular force sensor to in situ noninvasively probe and monitor single cell mechanical dynamics.Vascular smooth muscle cells(VSMCs)from healthy mouse and mouse with induced abdominal aorta aneurysm(AAA)were used for cell mechanobiological study.An ultrasound transducer(V312-SM,Olympus)was used to generate ultrasound pulses to excite lipid-encapsulated microbubbles(Targeson)binding to cell membrane through an RGD-integrin linkage to apply a transient nanonewton force to VSMCs seeded on the PDMS micropillar array.PDMS micropillar array was fabricated and functionalized as previously described [3] and acts as the mechanical force sensor in our platform.Upon a 1 HZ and 10-second ultrasound stimulation,calcium influx was clearly detected in both healthy and AAA-VSMCs by using the fluo-4 calcium sensor,suggesting the microbubble-integrin-actin cytoskeleton(CSK)linkage can serve as a mechanosensory to sense the ultrasound stimulation.We then examined how healthy and AAA VSMCs would exhibit adaptions to mechanical stimulation at a global cellular scale.After the onset of a 10-second ultrasound stimulation,control and AAA-VSMCs displayed distinct dynamics of CSK tension within 30 mins,in which the CSK tension of healthy VSMCs increased within the reinforcement period(0-5 min)and restored to their ground state with the relaxation period(5-10 min);yet AAA-VSMCs displayed compromised dynamics of such CSK tension upon calcium influx.Quantitative analysis and theoretical modelling revealed the critical roles of myosin motor contraction,F-actin filament polymerization in regulating cell mechanosensitive dynamics in response to a transient mechanical perturbation.The distinct force and CSK dynamics in healthy and AAA conditions indicates that the force-dependent CSK molecular kinetics is a critical factor governing the distinct mechanosensitive dynamics of cells under pathologically dysfunctional conditions.Our results reveal that the mechanical adaptive process of cells to mechanical stimulus can measure the cellular mechanobiological phenotypes featured in both pathologically healthy and diseased context.We demonstrated that an altered mechanobiological phenotype,i.e.AAA-VSMCs with distinct actomyosin-CSK properties potentiates a mechanical maladaptation that reflects progressive accumulation of cellular damage and dysfunction.This may further reveal the pathogenic contexts and their physical mediators featuring biophysical dysregulation in cardiovascular diseases.
文摘Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent after- shocks. The results show that the spatial distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric, which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic and static stresses should be con- sidered other than only either of them when studying aftershock triggering in near field.
基金supported by the National Natural Science Foundation of China under Grant No.61071118the National Basic Research Program of China(973 Program)under Grant No.2012CB316004+1 种基金Special Fund of Chongqing Key Laboratory(CSTC)Chongqing Municipal Education Commission’s Science and Technology Research Project under Grant No.KJ111506
文摘In order to achieve dynamical optimization of mobility load balancing,we analyze the conflict between mobility load balancing and mobility robustness optimization caused by the improper operation of handover parameters.To this end,a method of Handover Parameters Adjustment for Conflict Avoidance(HPACA)is proposed.Considering the movement of users,HPCAC can dynamically adjust handover range to optimize the mobility load balancing.The movement of users is an important factor of handover,which has a dramatic impact on system performance.The numerical evaluation results show the proposed approach outperforms the existing method in terms of throughput,call blocking ratio,load balancing index,radio link failure ratio,ping-pong handover ratio and call dropping ratio.
基金Chinese Joint Seismological Science Foundation (602005).
文摘This paper briefly reviews basic theory of seismic stress triggering. Recent development on seismic stress triggering has been reviewed in the views of seismic static and dynamic stress triggering, application of viscoelastic model in seismic stress triggering, the relation between earthquake triggering and volcanic eruption or explosion, other explanation of earthquake triggering, etc. And some suggestions for further study on seismic stress triggering in near future are given.
基金The National Natural Science Foundation of China under contract Nos 41704049,41890813,91628301 and 41974068the Chinese Academy of Sciences under contract Nos QYZDY-SSW-DQC005 and 133244KYSB20180029+3 种基金the foundation of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0205the foundation of Youth Innovation Promotion Association,Chinese Academy of Sciences under contract No.YIPA2018385the United States National Science Foundation under contract No.EAR-1736197the Foundation of Science Foundation for the Earthquake Resilience of China Earthquake Administration under contract No.XH20072.
文摘Philippine archipelago (PA) has strong background seismicity,but there is no systematic study of earthquake triggering in this region. There are six earthquakes (M_(w) > 6) occurred between 2018/12/29 and 2019/09/29 in PA,which provides an excellent opportunity to investigate the triggering relationship among these events. We calculate the static Coulomb stress changes of the first five events,and find that the local seismicity after the 2018/12/29 M_(w) 7.0 earthquake is mostly associated with positive Coulomb stress changes,including the 2019/05/31 M_(w) 6.1 event,suggesting a possible triggering relationship. However,we cannot rule out the dynamic triggering mechanism,due to increased microseismicity in both positive and negative stress change regions,and an incomplete local catalog,especially right after the first M_(w) 7.0 mainshock. The dynamic stresses from these M_(w) > 6 events are large enough (from 5 kPa to 3532 kPa) to trigger subsequent events,but a lack of seismicity and waveform evidence does not support delayed dynamic triggering among these events,even the shortest time interval is less than 24 hours. In the past 45 years,the released seismic energy shows certain peaks every 5–10 years. However,earthquakes with M_(w) > 6.0 were relatively infrequent between 2004 and 2018 at PA. Hence,it is possible that several regions are relatively late in their earthquake cycles,which would enhance their susceptibility of being triggered by earthquakes at nearby and regional distances.
基金supported by the National Natural Science Foundation of China(Grant Nos.52334003 and 52274105)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.CX20240263).
文摘The dynamic response and failure characteristics of tunnels vary significantly under various dynamic disturbances.These characteristics are crucial for assessing structural stability and designing effective support for surrounding rock.In this study,the theoretical solution for the dynamic stress concentration factor(DSCF)of a circular tunnel subjected to cylindrical and plane P-waves was derived using the wave function expansion method.The existing equivalent blast stress wave was optimized and the Ricker wavelet was introduced to represent the seismic stress waves.By combining Fourier transform and Duhamel’s integral,the transient response of the underground tunnel under near-field blasts and far-field earthquakes was determined in both the frequency and time domains.The theoretical results were validated by comparing them with those obtained from numerical simulations using ANSYS LS-DYNA software.Numerical simulations were conducted to further investigate the damage characteristics of the underground tunnel and evaluate the effect of initial stress on structural failure under both types of disturbances.The theoretical and numerical simulation results indicated that the differences in the dynamic response and damage characteristics of the underground tunnel were primarily due to the curvature of the stress waves and transient load waveform.The locations of the maximum DSCF values differed between near-field blasts and far-field earthquakes,whereas the minimum DSCF values occurred at the same positions.Without initial stress,the blast stress waves caused spalling damage to the rock mass on the wave-facing side.Shear failure occurred near the areas with maximum DSCF values,and tensile failure occurred near the areas with minimum DSCF values.In contrast,damage occurred only near the areas with maximum DSCF values under seismic stress waves.Furthermore,the initial stress exacerbated spalling and shear damage while suppressing tensile failure.Hence,the blast stress waves no longer induced tensile failure on the tunnel sidewalls under initial stress.
基金Supported by the National Natural Science Foundation of China (Grant No. 40364001)the Key Lab. Open Foundation for Earth and Space Environment and Geodesy of the Ministry of Education of China (Grant No. 03-04-07)
文摘The spatiotemporal evolution patterns of complete Coulomb stress changes caused by 1988 Ms7.6 earthquake in Lancang-Gengma, Yunnan, are calculated and studied. And the triggering problems of Ms7.2 Gengma shock occurring 13 minutes after the main shock and of Ms5.0―6.9 aftershocks within 24 days after the main shock are discussed. The results show that the spatial distribution patterns of complete Coulomb stress changes of the Ms7.6 main shock are strongly asymmetric. The areas of positive dynamic and static Coulomb stress are both coincident well with the strong aftershocks' loca-tions. The Ms7.2 Gengma shock and most of strong aftershocks are subjected to the triggering effect of dynamic and static Coulomb stresses induced by the Ms7.6 Lancang earthquake.
基金the National Natural Science Foundation of China[Grant No.U1810102].
文摘In view of the three-dimensional dynamic abutment pressure,the influence of the far-field hard stratum(FHS)in deep,thick coal seams is indeterminant.Based on elastic foundation theory,a three-dimensional dynamic prediction model of the abutment pressure was established.Using this model,the dynamic change in the coal seam abutment pressure caused by the movement of the FHS was studied,and a method for determining the dynamic change range of the abutment pressure was developed.The results of the new prediction model of the abutment pressure are slightly higher than the measured values,with an error of 0.51%,which avoids the shortcomings of the results because the Winkler foundation model results are lower than the measured values and have an error of 9.98%.As time progresses,the abutment pressure and its distribution range are affected by the FHS movement,which has the characteristics of gradually increasing dynamic change until the FHS fractures.The peak value of the abutment pressure increases linearly with time,and the influence range increases with time following a power function with an exponent of less than 1.The influence range of the FHS movement on the abutment pressure ahead of the working face,behind the working face,and along the working face is 10 times,25 times,and 17 times the mining thickness,respectively.According to the actual geological parameters,the dynamic change range of the coal seam abutment pressure was determined by drawing an additional stress curve and by determining the threshold value.These research results are of great significance to the partition optimization of the roadway support design of deep,thick coal seams.
