The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with ...The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with a precut planar fault was loaded on a horizontally biaxial servo-controlled press machine to create stick-slip conditions.Digital images of the sample surface were taken by a high-speed camera at a rate of 1000 frames per second during the stick-slip motion and processed using a 2D digital image correlation method to obtain the displacement field.We define a synergism coefficient that describes the relative dispersion of the accumulative fault slip.The results reveal that:(1)a local pre-slip area spreads very slowly along the fault before the MIS develops.It extends at a higher but still slow speed during meta-instable state I(MIS-I).During the final^1.5%of MIS,in meta-instable state II(MIS-II),the local pre-slip area first extends at a speed of^0.9 m/s,and then expands out of the observed image area at a very high speed.These results indicate that the local pre-slip area transforms from a state of quasi-static extension in MIS-I to quasi-dynamic extension in MIS-II.(2)The synergism coefficient of the fault slip decreases to half of its original value in MIS-I and to a quarter of its original value in MIS-II.This continuous decrease of synergism coefficient indicates that the strengthening of fault slip synergism is a characteristic of MIS.(3)Furthermore,the unstable sliding stage includes three sliding processes:initial-,fast-,and adjusted-sliding.There are two pauses between the three sliding processes.展开更多
This article proposes a relay camera videometrics based method to convert an unstable measuring platform to a static reference to solve the problems of large error or invalidation caused by measuring platform instabil...This article proposes a relay camera videometrics based method to convert an unstable measuring platform to a static reference to solve the problems of large error or invalidation caused by measuring platform instability in photogrammetric and videometric measurements.The method installs a relay camera on the unstable platform and captures images of a reference marker fixed on a static reference or vice versa to resolve the 3D movement of the unstable platform relative to the static reference,based on which it corrects the error of the measured results and thus eliminating the influence of the platform movement.It finds new and important applications for videometrics by making high-precision dynamic measurement possible on unstable platforms.Verification experiments and numerical simulations have proven its validity and practicability.展开更多
The impact of the lattice strain on the charge/orbital ordering state was studied by using a heterostructure composed with elec- tron-doped La0.9Hf0.1MnO3 （LHMO） and ferro- and piezoelectric 0.67Pb（Mgl/3Nb2/3）O3-0...The impact of the lattice strain on the charge/orbital ordering state was studied by using a heterostructure composed with elec- tron-doped La0.9Hf0.1MnO3 （LHMO） and ferro- and piezoelectric 0.67Pb（Mgl/3Nb2/3）O3-0.33PbTiO3. The ferroelectric poling induces a significant reduction in the biaxial tensile strain in the LHMO film, leading to a decrease in the film resistance over the whole temperature range and an increase in the insulator to metal transition temperature TIM. The resistance of LHMO film exhibits different responses to the external electric fields and lattice deformation, which is attributed to the coactions of con- verse piezoelectric effect and ferroelectric polarity effect. The modification of charge/orbital ordering phase by the electric fields and ferroelectric polarization suggests that the unstable states in the manganites are sensitive to strain effects.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41172180)Basic Research Funds from the Institute of Geology,China Earthquake Administration(Grant No.IGCEA1203)
文摘The meta-instable state(MIS)is the final stage before fault instability during stick-slip movement.Thus,identification of MIS is of great significance for assessing earthquake hazard in fault zones.A rock sample with a precut planar fault was loaded on a horizontally biaxial servo-controlled press machine to create stick-slip conditions.Digital images of the sample surface were taken by a high-speed camera at a rate of 1000 frames per second during the stick-slip motion and processed using a 2D digital image correlation method to obtain the displacement field.We define a synergism coefficient that describes the relative dispersion of the accumulative fault slip.The results reveal that:(1)a local pre-slip area spreads very slowly along the fault before the MIS develops.It extends at a higher but still slow speed during meta-instable state I(MIS-I).During the final^1.5%of MIS,in meta-instable state II(MIS-II),the local pre-slip area first extends at a speed of^0.9 m/s,and then expands out of the observed image area at a very high speed.These results indicate that the local pre-slip area transforms from a state of quasi-static extension in MIS-I to quasi-dynamic extension in MIS-II.(2)The synergism coefficient of the fault slip decreases to half of its original value in MIS-I and to a quarter of its original value in MIS-II.This continuous decrease of synergism coefficient indicates that the strengthening of fault slip synergism is a characteristic of MIS.(3)Furthermore,the unstable sliding stage includes three sliding processes:initial-,fast-,and adjusted-sliding.There are two pauses between the three sliding processes.
基金supported by the National Natural Science Foundation of China (Grant Nos.11072263,10727202)
文摘This article proposes a relay camera videometrics based method to convert an unstable measuring platform to a static reference to solve the problems of large error or invalidation caused by measuring platform instability in photogrammetric and videometric measurements.The method installs a relay camera on the unstable platform and captures images of a reference marker fixed on a static reference or vice versa to resolve the 3D movement of the unstable platform relative to the static reference,based on which it corrects the error of the measured results and thus eliminating the influence of the platform movement.It finds new and important applications for videometrics by making high-precision dynamic measurement possible on unstable platforms.Verification experiments and numerical simulations have proven its validity and practicability.
基金supported by the Research Grant Council of Hong Kong(Grant No. HKU 702409P)the Seed Funding by the University of Hong Kong
文摘The impact of the lattice strain on the charge/orbital ordering state was studied by using a heterostructure composed with elec- tron-doped La0.9Hf0.1MnO3 （LHMO） and ferro- and piezoelectric 0.67Pb（Mgl/3Nb2/3）O3-0.33PbTiO3. The ferroelectric poling induces a significant reduction in the biaxial tensile strain in the LHMO film, leading to a decrease in the film resistance over the whole temperature range and an increase in the insulator to metal transition temperature TIM. The resistance of LHMO film exhibits different responses to the external electric fields and lattice deformation, which is attributed to the coactions of con- verse piezoelectric effect and ferroelectric polarity effect. The modification of charge/orbital ordering phase by the electric fields and ferroelectric polarization suggests that the unstable states in the manganites are sensitive to strain effects.
