This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquake...This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquakes occurring along the Tancheng-Lujiang fault zone and its bilateral areas in Shandong,Liaoning,Hebei,Jiangsu and Jiangxi Provinces in the period from 1966 to 2005. Results show that:( 1) For M7. 0 and M6. 0earthquakes,med-term abnormities are the greatest in number,short-term abnormities come second,and imminent anomalies are the least. For M5. 0 earthquakes,short-term abnormities are often the most in number,imminent anomalies come second,and the med-term ones are the least.( 2) Precursory anomalies are periodical,part of the med and short-term anomalies are shown as short-term and imminent anomalies during their development.( 3) The development of precursor shows quasi-synchronism; the closer to earthquake occurrence time,the more turning changes of anomalies will appear.( 4)Anomalies mainly occur within an epicenter distance of 100 km, showing a relative concentrated distribution in space,and the shorter the distance to epicenter,the higher the anomaly station / item rate.( 5) The spatial distribution of anomalies is relatively correlated to the strike of structures,having a good consistency with the structure.( 6)There is no significant correlation between duration of abnormities and the epicenter distance.( 7) The higher the magnitude of the earthquake,the greater the amplitude of the abnormities measured with the same observation approach.( 8) In terms of the itemsof the observations,fluid abnormities are the greatest in number,followed by deformation and electromagnetism observations.( 9) For all observation items,med and short-term abnormities make up the majority and short-term and imminent anomalies the minority.( 10) In fluid,deformation and electromagnetism observations,fairly reliable anomalies are about double the number of reliable anomalies.展开更多
Low-energy electron microscopy （LEEM） has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride （h-BN） films. The h-B...Low-energy electron microscopy （LEEM） has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride （h-BN） films. The h-BN films are grown on heteroepitaxial Co using chemical vapor deposition （CVD） at low pressure. Our findings from LEEM studies include the growth of monolayer film having two, oppositely oriented, triangular BN domains commensurate with the Co lattice. The growth of h-BN appears to be self-limiting at a monolayer, with thicker domains only appearing in patches, presumably initiated between domain boundaries. Reflectivity measurements of the thicker h-BN films show oscillations resulting from the resonant electron transmission through quantized electronic states of the h-BN films, with the number of minima scaling up with the number of h-BN layers. First principles density functional theory （DFT） calculations show that the positions of oscillations are related to the electronic band structure of h-BN.展开更多
基金supported financially by Science for Earthquake Resilience(XH14064Y)the open foundation of the State Key Laboratory of Geodesy and Earth's Dynamics(SKLGED2014-5-2-E)the major national science and technology support project(2012BAK19B04-05-02)
文摘This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquakes occurring along the Tancheng-Lujiang fault zone and its bilateral areas in Shandong,Liaoning,Hebei,Jiangsu and Jiangxi Provinces in the period from 1966 to 2005. Results show that:( 1) For M7. 0 and M6. 0earthquakes,med-term abnormities are the greatest in number,short-term abnormities come second,and imminent anomalies are the least. For M5. 0 earthquakes,short-term abnormities are often the most in number,imminent anomalies come second,and the med-term ones are the least.( 2) Precursory anomalies are periodical,part of the med and short-term anomalies are shown as short-term and imminent anomalies during their development.( 3) The development of precursor shows quasi-synchronism; the closer to earthquake occurrence time,the more turning changes of anomalies will appear.( 4)Anomalies mainly occur within an epicenter distance of 100 km, showing a relative concentrated distribution in space,and the shorter the distance to epicenter,the higher the anomaly station / item rate.( 5) The spatial distribution of anomalies is relatively correlated to the strike of structures,having a good consistency with the structure.( 6)There is no significant correlation between duration of abnormities and the epicenter distance.( 7) The higher the magnitude of the earthquake,the greater the amplitude of the abnormities measured with the same observation approach.( 8) In terms of the itemsof the observations,fluid abnormities are the greatest in number,followed by deformation and electromagnetism observations.( 9) For all observation items,med and short-term abnormities make up the majority and short-term and imminent anomalies the minority.( 10) In fluid,deformation and electromagnetism observations,fairly reliable anomalies are about double the number of reliable anomalies.
文摘Low-energy electron microscopy （LEEM） has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride （h-BN） films. The h-BN films are grown on heteroepitaxial Co using chemical vapor deposition （CVD） at low pressure. Our findings from LEEM studies include the growth of monolayer film having two, oppositely oriented, triangular BN domains commensurate with the Co lattice. The growth of h-BN appears to be self-limiting at a monolayer, with thicker domains only appearing in patches, presumably initiated between domain boundaries. Reflectivity measurements of the thicker h-BN films show oscillations resulting from the resonant electron transmission through quantized electronic states of the h-BN films, with the number of minima scaling up with the number of h-BN layers. First principles density functional theory （DFT） calculations show that the positions of oscillations are related to the electronic band structure of h-BN.
