Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distri...Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distribution is calculated by the air-bearing model at the head/disk interface with respect to the helium content and the pressure obtained is then input to the molecular dynamics model to understand the lubricant transfer mechanism. Finally, the effects of pressure at the boundary condition and disk velocity on lubricant transfer are discussed in relation to the helium fraction within the air-helium gas mixtures. Results show there is a decrease in the pressure difference with an increase in the helium percentage, which leads to a decrease in the volume of the lubricant transferred. The results also suggest that the lubricant is not easily to transfer in gas mixtures with a high percentage of helium, even when both higher disk velocities and pressure boundary conditions are applied.展开更多
The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on N...The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on Navier-Stokes （NS） and continuity equations. The air bearing pressure on the surface of the lubrication film is solved by the modified Reynolds equation based on Fukui and Kaneko （FK） model. Then the lubricant film deformations for a plane slider and double-track slider are obtained. The equation of lubricant film thickness is deduced with the consideration of van der Waals force, the air bearing pressure, the surface tension, and the external stresses. The lubricant depletion under heat source is simulated and the effects of different working conditions including initial thickness, flying height and the speed of the disk on lubricant depletion are discussed. The main factors that cause the lubricant flow and depletion are analyzed and the ways to reduce the film thickness deformation are proposed. The simulation results indicate that the shearing stress is the most important factor that causes the thickness deformation and other terms listed in the equation have little influence. The thickness deformation is dependent on the working parameter, and the thermal condition evaporation is the most important factor.展开更多
Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, w...Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, which is one of the materials in slider. A partial fluorinated hexaphenoxy cyclotriphosphazene chemical, X-1 P, was analyzed to research on its function to reduce the cata- lytic decomposition of lubricant. The surface free energy of X-1 P coated on head surface was also investigated. Contact start-stop (CSS) tester was employed to investigate the reflow effective of X-1 P on lubricant PFPE. Results indicate that thermal stability and reflow of lubricant will be im- proved in the presence of X-1 P on the slider.展开更多
Head waves are usually considered to be the refracted waves propagating along flat interfaces with an underlying higher velocity.However,the path that the rays travel along in media with irregular interfaces is not cl...Head waves are usually considered to be the refracted waves propagating along flat interfaces with an underlying higher velocity.However,the path that the rays travel along in media with irregular interfaces is not clear.Here we study the problem by simulation using a new approach of the spectral-element method with some overlapped elements（SEMO） that can accurately evaluate waves traveling along an irregular interface.Consequently,the head waves are separated from interface waves by a time window.Thus,their energy and arrival time changes can be analyzed independently.These analyses demonstrate that,contrary to the case for head waves propagating along a flat interface,there are two mechanisms for head waves traveling along an irregular interface：a refraction mechanism and transmission mechanism.That is,the head waves may be refracted waves propagating along the interface or transmitted waves induced by the waves propagating in the higher-velocity media.Such knowledge will be helpful in constructing a more accurate inversion method,such as head wave travel-time tomography,and in obtaining a more accurate model of subsurface structure which is very important for understanding the formation mechanism of some special areas,such as the Tibetan Plateau.展开更多
The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological mode...The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological model. The perturbation theory is employed to set up the dynamic pressure equation. The Reynolds equation and dynamic pressure equations are solved by finite difference method. The results obtained by the difference methods agree well with that calculated by the close solutions. IBM3370 slider is employed as a physical model. The slider of the system can keep flying at 20 nm height, which promises a potential application on high density recording device.展开更多
When the decrease in the space between magnetic head and disk arrived at 10 nm or less, which is much lower than the mean free path of gas molecules, the gas flow presents distinctive features against the macro featur...When the decrease in the space between magnetic head and disk arrived at 10 nm or less, which is much lower than the mean free path of gas molecules, the gas flow presents distinctive features against the macro features because of the rarefied effects. The modified Reynolds equation considering rarefied gas effect is used to calculate the rarefied region of a negative pressure magnetic head working in the distance of 10 nm. Inverse Knudsen number was adopted to calculating the ratio of the rarefied area. According to the numerical resuks, discussions and analyses are then presented to reveal the rarefied effect on the working performances of a magnetic head. The results show that the magnetic head works in the slip-flow and transition regions and moves to the transition region with the increase in velocity. Furthermore, the maximum rarefied effects occur at the side edges where the flying height is thinner and pressure is lower, rather than in the minimum flying height on the rear. The results also show that with considering the rarefied effects, the load-carrying capacity of the magnetic head and the maximum pressure decrease significantly, but the minimum pressure slightly changes.展开更多
For the purpose of solving the problem that too large pole tip recession （PTR） is produced in magnetic rigid disk heads by mechanical polishing, a chemical mechanical nano-grinding experiment is performed by using a...For the purpose of solving the problem that too large pole tip recession （PTR） is produced in magnetic rigid disk heads by mechanical polishing, a chemical mechanical nano-grinding experiment is performed by using a float-piece polisher with a tin plate to achieve a more plane and smoother surface. A basal solution, addition agents and a range of pH value are suitably selected to find a kind of slurry, with which the PTR can be controlled on sub-nanometer scale and the giant magnetic resistance （GMR） corrosion and electrostatic damage （ESD） can be avoided. Moreover, the cause that TiC protrudes from the substrate surface of the heads is studied. The appropriate shape and size of diamond abrasive are selected according to the chemical activation of A1203 and TiC in the same slurry. In this way, the chemical and mechanical interactions are optimized and the optimal surface that has small PTR and TiC asperity is achieved. Ultimatily, the chemical mechanical nano-grinding in combination with mechanical nano-grinding is adopted. Sub-nanometer PTR is achieved and the TiC asperity is eliminated by the chemical mechanical nano-grinding with large size ofmonocrystalline followed by mechanical nano-grinding with smalle polycrystalline diamonds.展开更多
Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Th...Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors （moisture content） and output factors （head brown rice recovery, specific energy consumption）. Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice （77.4%） and the minimum value of specific energy consumption （0.66 kWh/ton） corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content （13.7%）, head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.展开更多
This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engin...This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.展开更多
We studied the quantum dot-liposome complex (QLC), which is the giant unilamellar vesicle with quantum dots (QDs) incorporated in its lipid bilayer. A spin coating method in conjunction with the electroformation techn...We studied the quantum dot-liposome complex (QLC), which is the giant unilamellar vesicle with quantum dots (QDs) incorporated in its lipid bilayer. A spin coating method in conjunction with the electroformation technique yielded vesicles with highly homogeneous unilamellar structure. We observed QD size dependence of the QLC formation: QLCs form with blue, green and yellow-emission QD (core radius ~1.05 nm, 1.25 nm and 1.65 nm) but not with red-emission QD (core radius ~2.5 nm). In order to explain this size dependence, we made a simple model explaining the QD size effect on QLC formation in terms of the molecular packing parameter and the lipid conformational change. This model predicts that QDs below a certain critical size (radius ≈ 1.8 nm) can stably reside in a lipid bilayer of 4 - 5 nm in thickness for Egg-PC lipids. This is consistent with our previous experimental results. In the case of red-emission QD, QD-aggregations are only observed on the fluorescent microscopy instead of QLC. We expected that the reduction of packing parameter (P) would lead to the change of specific QD radius. This prediction could be verified by our experimental observation of the shift of the specific QD size by mixing DOPG.展开更多
Influenza causes seasonal outbreaks yearly and unpredictable pandemics with high morbidity and mortality rates.Despite significant efforts to address influenza,it remains a major threat to human public health.This iss...Influenza causes seasonal outbreaks yearly and unpredictable pandemics with high morbidity and mortality rates.Despite significant efforts to address influenza,it remains a major threat to human public health.This issue is partially due to the lack of antiviral drugs with potent antiviral activity and broad reactivity against all influenza virus strains and the rapid emergence of drug-resistant variants.Moreover,designing a universal influenza vaccine that is sufficiently immunogenic to induce universal antibodies is difficult.Some novel epitopes hidden in the hemagglutinin(HA)trimeric interface have been discovered recently,and a number of antibodies targeting these epitopes have been found to be capable of neutralizing a broad range of influenza isolates.These findings may have important implications for the development of universal influenza vaccines and antiviral drugs.In this review,we focused on the antibodies targeting these newly discovered epitopes in the HA domain of the influenza virus to promote the development of universal anti-influenza antibodies or vaccines and extend the discovery to other viruses with similar conformational changes in envelope proteins.展开更多
A devastating MW 7.7 earthquake struck near Mandalay,Myanmar,on March 28,2025,causing extensive damage and casualties across Myanmar and neighboring regions.The 2025 event occurred in a well-recognized seismic gap alo...A devastating MW 7.7 earthquake struck near Mandalay,Myanmar,on March 28,2025,causing extensive damage and casualties across Myanmar and neighboring regions.The 2025 event occurred in a well-recognized seismic gap along the Sagaing Fault.Here we focus on the mainshock rupture properties based on backprojection of teleseismic P waves and early aftershock locations,analysis of near-field seismic recordings for the mainshock initiation,and remotely triggered seismicity following the MW 7.7 mainshock.We find that the~500 km mainshock rupture can be revealed by both rapid back-projection of teleseismic P waves from multiple broadband arrays and early aftershock locations within about 3 h from the Thai Meteorological Department(TMD)catalog.The rupture speed went supershear in the southward propagation after the initial bilateral subshear ruptures,as expected for large strike-slip earthquakes of such sizes.Clear fault zone head waves that are reflected along a bimaterial fault interface are observed at the only near-fault station GE.NPW on the slower side about 2.6 km away from the Sagaing fault,consistent with the preferred direction of a supershear rupture propagating to the south.In addition,aftershocks from the regional TMD catalog appear to be located mostly to the east of the mainshock rupture.While we cannot completely rule out mis-locations from the one-sided station distribution,these off-fault seismicity could also be explained by reactivations of subsidiary faults within the Shan Plateau,or an eastward dipping of the mainshock rupture plane.Although no immediate foreshocks were found from several nearby stations,we identify one sub-event with magnitude~6 at the beginning of the mainshock with a slightly different focal mechanism about 20–30 km south of the hypocenter determined by the United States Geological Survey(USGS).The mainshock also occurred when the tidal stresses reached its maximum on the right-lateral strike-slip fault,likely indicating that the timing of the mainshock is modulated by the solid earth tides.We find a significant increase of seismic activity near the Thailand/Myanmar border,in multiple(geothermally active)regions of Yunnan province in Southwest China,as well as the Xingfengjian reservoir in the Guangdong province in South China.Because static stress changes from the mainshock are small but negative near the Thailand/Myanmar border,the occurrence of microseismicity in this and other regions can be mainly explained by remote triggering from dynamic stress changes of the mainshock rupture.Our analyses demonstrate the importance of rapid analysis on openly available seismic data and catalog to better understand the rupture properties and triggered seismicity following large earthquakes.展开更多
The reflected field of pulsed cylindrical waves from a liquid-solid interface is studied by the numerical method and the experimental method. The reflected field is calculated and shown in gray pictures. The calculate...The reflected field of pulsed cylindrical waves from a liquid-solid interface is studied by the numerical method and the experimental method. The reflected field is calculated and shown in gray pictures. The calculated incident angles θn (n=1, 2, 3, ...) of a series of minimums (or nulls) on the reflected wavefront are presented. The measured angle of the minimum from Schlieren photograph is consistent with that by calculation. The appearance of minimums is explained by the interference between the reflected wave and the head wave, and by the radiated dissipation of the head wave. The leading phase angle of the head wave to the reflected wave is proved to be about 3π/4 by the numerical calculation.展开更多
基金supported by the National Natural Science Foundation of China (51505093, 51605113)the Young Talents Project of Education Department of Guizhou Province (KY[2016]116)+1 种基金the Science and Technology Project of Guizhou Province ([2016]1035)the Science and Technology Innovation Project for Overseas Scholars of Guizhou Province
文摘Lubricant transfer and distribution at the head/disk interface in air-helium gas mixtures is investigated using a developed model that combines an air-bearing model with a molecular dynamics model. The pressure distribution is calculated by the air-bearing model at the head/disk interface with respect to the helium content and the pressure obtained is then input to the molecular dynamics model to understand the lubricant transfer mechanism. Finally, the effects of pressure at the boundary condition and disk velocity on lubricant transfer are discussed in relation to the helium fraction within the air-helium gas mixtures. Results show there is a decrease in the pressure difference with an increase in the helium percentage, which leads to a decrease in the volume of the lubricant transferred. The results also suggest that the lubricant is not easily to transfer in gas mixtures with a high percentage of helium, even when both higher disk velocities and pressure boundary conditions are applied.
基金Project supported by the National Natural Science Foundation of China(Grant No.51275124)
文摘The characteristics of lubricant film at head/disk interface （HDI） are essential to the stability of hard disk drives. In this study, the theoretical models of the lubricant flow and depletion are deduced based on Navier-Stokes （NS） and continuity equations. The air bearing pressure on the surface of the lubrication film is solved by the modified Reynolds equation based on Fukui and Kaneko （FK） model. Then the lubricant film deformations for a plane slider and double-track slider are obtained. The equation of lubricant film thickness is deduced with the consideration of van der Waals force, the air bearing pressure, the surface tension, and the external stresses. The lubricant depletion under heat source is simulated and the effects of different working conditions including initial thickness, flying height and the speed of the disk on lubricant depletion are discussed. The main factors that cause the lubricant flow and depletion are analyzed and the ways to reduce the film thickness deformation are proposed. The simulation results indicate that the shearing stress is the most important factor that causes the thickness deformation and other terms listed in the equation have little influence. The thickness deformation is dependent on the working parameter, and the thermal condition evaporation is the most important factor.
文摘Stable lubrication is essential to slider/disk interface of computer hard disk drive. Inert lubricant perfluoropolyether (PFPE) on magnetic hard disk in computer is still prone to catalytic decomposition by Al_2O_3, which is one of the materials in slider. A partial fluorinated hexaphenoxy cyclotriphosphazene chemical, X-1 P, was analyzed to research on its function to reduce the cata- lytic decomposition of lubricant. The surface free energy of X-1 P coated on head surface was also investigated. Contact start-stop (CSS) tester was employed to investigate the reflow effective of X-1 P on lubricant PFPE. Results indicate that thermal stability and reflow of lubricant will be im- proved in the presence of X-1 P on the slider.
基金supported by the National Natural Science Foundation of China (Grant Nos.40874027,90715020,and 90915012)the Institute of Geophysics of the China Earthquake Administration (Grant No.DQJB07B06)Special Public Welfare Industry (Grant Nos.20070804 and 200808008)
文摘Head waves are usually considered to be the refracted waves propagating along flat interfaces with an underlying higher velocity.However,the path that the rays travel along in media with irregular interfaces is not clear.Here we study the problem by simulation using a new approach of the spectral-element method with some overlapped elements（SEMO） that can accurately evaluate waves traveling along an irregular interface.Consequently,the head waves are separated from interface waves by a time window.Thus,their energy and arrival time changes can be analyzed independently.These analyses demonstrate that,contrary to the case for head waves propagating along a flat interface,there are two mechanisms for head waves traveling along an irregular interface：a refraction mechanism and transmission mechanism.That is,the head waves may be refracted waves propagating along the interface or transmitted waves induced by the waves propagating in the higher-velocity media.Such knowledge will be helpful in constructing a more accurate inversion method,such as head wave travel-time tomography,and in obtaining a more accurate model of subsurface structure which is very important for understanding the formation mechanism of some special areas,such as the Tibetan Plateau.
文摘The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological model. The perturbation theory is employed to set up the dynamic pressure equation. The Reynolds equation and dynamic pressure equations are solved by finite difference method. The results obtained by the difference methods agree well with that calculated by the close solutions. IBM3370 slider is employed as a physical model. The slider of the system can keep flying at 20 nm height, which promises a potential application on high density recording device.
基金supported by National Basic Research and Development Program of China (973 Program, Grant No. 2003CB716205)
文摘When the decrease in the space between magnetic head and disk arrived at 10 nm or less, which is much lower than the mean free path of gas molecules, the gas flow presents distinctive features against the macro features because of the rarefied effects. The modified Reynolds equation considering rarefied gas effect is used to calculate the rarefied region of a negative pressure magnetic head working in the distance of 10 nm. Inverse Knudsen number was adopted to calculating the ratio of the rarefied area. According to the numerical resuks, discussions and analyses are then presented to reveal the rarefied effect on the working performances of a magnetic head. The results show that the magnetic head works in the slip-flow and transition regions and moves to the transition region with the increase in velocity. Furthermore, the maximum rarefied effects occur at the side edges where the flying height is thinner and pressure is lower, rather than in the minimum flying height on the rear. The results also show that with considering the rarefied effects, the load-carrying capacity of the magnetic head and the maximum pressure decrease significantly, but the minimum pressure slightly changes.
基金National Natural Science Foundation of China(No. 50390061).
文摘For the purpose of solving the problem that too large pole tip recession （PTR） is produced in magnetic rigid disk heads by mechanical polishing, a chemical mechanical nano-grinding experiment is performed by using a float-piece polisher with a tin plate to achieve a more plane and smoother surface. A basal solution, addition agents and a range of pH value are suitably selected to find a kind of slurry, with which the PTR can be controlled on sub-nanometer scale and the giant magnetic resistance （GMR） corrosion and electrostatic damage （ESD） can be avoided. Moreover, the cause that TiC protrudes from the substrate surface of the heads is studied. The appropriate shape and size of diamond abrasive are selected according to the chemical activation of A1203 and TiC in the same slurry. In this way, the chemical and mechanical interactions are optimized and the optimal surface that has small PTR and TiC asperity is achieved. Ultimatily, the chemical mechanical nano-grinding in combination with mechanical nano-grinding is adopted. Sub-nanometer PTR is achieved and the TiC asperity is eliminated by the chemical mechanical nano-grinding with large size ofmonocrystalline followed by mechanical nano-grinding with smalle polycrystalline diamonds.
文摘Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors （moisture content） and output factors （head brown rice recovery, specific energy consumption）. Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice （77.4%） and the minimum value of specific energy consumption （0.66 kWh/ton） corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content （13.7%）, head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.
文摘This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.
文摘We studied the quantum dot-liposome complex (QLC), which is the giant unilamellar vesicle with quantum dots (QDs) incorporated in its lipid bilayer. A spin coating method in conjunction with the electroformation technique yielded vesicles with highly homogeneous unilamellar structure. We observed QD size dependence of the QLC formation: QLCs form with blue, green and yellow-emission QD (core radius ~1.05 nm, 1.25 nm and 1.65 nm) but not with red-emission QD (core radius ~2.5 nm). In order to explain this size dependence, we made a simple model explaining the QD size effect on QLC formation in terms of the molecular packing parameter and the lipid conformational change. This model predicts that QDs below a certain critical size (radius ≈ 1.8 nm) can stably reside in a lipid bilayer of 4 - 5 nm in thickness for Egg-PC lipids. This is consistent with our previous experimental results. In the case of red-emission QD, QD-aggregations are only observed on the fluorescent microscopy instead of QLC. We expected that the reduction of packing parameter (P) would lead to the change of specific QD radius. This prediction could be verified by our experimental observation of the shift of the specific QD size by mixing DOPG.
基金This work was supported by the National Natural Science Foundation of China(Nos.81822027 and 81630090)the National Key R&D Program of China(No.2019YFA0904400)+1 种基金the National Science and Technology Major Projects of Infectious Disease funds(No.2018ZX10301403)the grant from the Chinese Academy of Medical Sciences(No.2019PT350002).
文摘Influenza causes seasonal outbreaks yearly and unpredictable pandemics with high morbidity and mortality rates.Despite significant efforts to address influenza,it remains a major threat to human public health.This issue is partially due to the lack of antiviral drugs with potent antiviral activity and broad reactivity against all influenza virus strains and the rapid emergence of drug-resistant variants.Moreover,designing a universal influenza vaccine that is sufficiently immunogenic to induce universal antibodies is difficult.Some novel epitopes hidden in the hemagglutinin(HA)trimeric interface have been discovered recently,and a number of antibodies targeting these epitopes have been found to be capable of neutralizing a broad range of influenza isolates.These findings may have important implications for the development of universal influenza vaccines and antiviral drugs.In this review,we focused on the antibodies targeting these newly discovered epitopes in the HA domain of the influenza virus to promote the development of universal anti-influenza antibodies or vaccines and extend the discovery to other viruses with similar conformational changes in envelope proteins.
基金supported by the National Nonprofit Fundamental Research Grant of China, Institute of Geology, China Earthquake Administration (grant number IGCEA2504)partially supported by National Science Foundation Grant RISE-2425889+1 种基金supported by Earthquake Prediction Open Fund, China Earthquake Administration (Grant No. XH25006D)supported by the International Partnership Program of Chinese Academy of Sciences (Grant No. 164GJHZ2023006MI)
文摘A devastating MW 7.7 earthquake struck near Mandalay,Myanmar,on March 28,2025,causing extensive damage and casualties across Myanmar and neighboring regions.The 2025 event occurred in a well-recognized seismic gap along the Sagaing Fault.Here we focus on the mainshock rupture properties based on backprojection of teleseismic P waves and early aftershock locations,analysis of near-field seismic recordings for the mainshock initiation,and remotely triggered seismicity following the MW 7.7 mainshock.We find that the~500 km mainshock rupture can be revealed by both rapid back-projection of teleseismic P waves from multiple broadband arrays and early aftershock locations within about 3 h from the Thai Meteorological Department(TMD)catalog.The rupture speed went supershear in the southward propagation after the initial bilateral subshear ruptures,as expected for large strike-slip earthquakes of such sizes.Clear fault zone head waves that are reflected along a bimaterial fault interface are observed at the only near-fault station GE.NPW on the slower side about 2.6 km away from the Sagaing fault,consistent with the preferred direction of a supershear rupture propagating to the south.In addition,aftershocks from the regional TMD catalog appear to be located mostly to the east of the mainshock rupture.While we cannot completely rule out mis-locations from the one-sided station distribution,these off-fault seismicity could also be explained by reactivations of subsidiary faults within the Shan Plateau,or an eastward dipping of the mainshock rupture plane.Although no immediate foreshocks were found from several nearby stations,we identify one sub-event with magnitude~6 at the beginning of the mainshock with a slightly different focal mechanism about 20–30 km south of the hypocenter determined by the United States Geological Survey(USGS).The mainshock also occurred when the tidal stresses reached its maximum on the right-lateral strike-slip fault,likely indicating that the timing of the mainshock is modulated by the solid earth tides.We find a significant increase of seismic activity near the Thailand/Myanmar border,in multiple(geothermally active)regions of Yunnan province in Southwest China,as well as the Xingfengjian reservoir in the Guangdong province in South China.Because static stress changes from the mainshock are small but negative near the Thailand/Myanmar border,the occurrence of microseismicity in this and other regions can be mainly explained by remote triggering from dynamic stress changes of the mainshock rupture.Our analyses demonstrate the importance of rapid analysis on openly available seismic data and catalog to better understand the rupture properties and triggered seismicity following large earthquakes.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 19604008 and 10074039).
文摘The reflected field of pulsed cylindrical waves from a liquid-solid interface is studied by the numerical method and the experimental method. The reflected field is calculated and shown in gray pictures. The calculated incident angles θn (n=1, 2, 3, ...) of a series of minimums (or nulls) on the reflected wavefront are presented. The measured angle of the minimum from Schlieren photograph is consistent with that by calculation. The appearance of minimums is explained by the interference between the reflected wave and the head wave, and by the radiated dissipation of the head wave. The leading phase angle of the head wave to the reflected wave is proved to be about 3π/4 by the numerical calculation.
