A wave equation of rock under axial static stress is established using the equivalent medium method by modifying the Kelvin-Voigt model.The analytical formulas of longitudinal velocity,space and time attenuation coeff...A wave equation of rock under axial static stress is established using the equivalent medium method by modifying the Kelvin-Voigt model.The analytical formulas of longitudinal velocity,space and time attenuation coefficients and response frequency are obtained by solving the equation using the harmonic method.A series of experiments on stress wave propagation through rock under different axial static stresses have been conducted.The proposed models of stress wave propagation are then verified by comparing experimental results with theoretical solutions.Based on the verified theoretical models,the influences of axial static stress on longitudinal velocity,space and time attenuation coefficients and response frequency are investigated by detailed parametric studies.The results show that the proposed theoretical models can be used to effectively investigate the effects of axial static stress on the stress wave propagation in rock.The axial static stress influences stress wave propagation characteristics of porous rock by varying the level of rock porosity and damage.Moreover,the initial porosity,initial elastic modulus of the rock voids and skeleton,viscous coefficient and vibration frequency have significant effects on the P-wave velocity,attenuation characteristics and response frequency of the stress wave in porous rock under axial static stress.展开更多
Based on digital seismograms recorded by 11 stations of the Xiaowan Reservoir-induced Earthquake Monitoring Network from May 21,2005 to September 2006,we calculated the inelastic attenuation near Xiaowan reservoir usi...Based on digital seismograms recorded by 11 stations of the Xiaowan Reservoir-induced Earthquake Monitoring Network from May 21,2005 to September 2006,we calculated the inelastic attenuation near Xiaowan reservoir using Atkinson method.We got the relation of Q value to frequency as Q(f)=225.8 f 0.332.Using the Moya method we got the site response of the 11 stations of Xiaowan Network and source parameters of 43 earthquakes.The source parameters were discussed briefly.展开更多
The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to ...The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to identify the vibratory characteristics of the structure. The main advantage of the technique is that the identification of the parameters of the structure is achieved without previous knowledge of the excitation forces. This paper extends the random decrement technique to obtain the mode shapes of the structure using the concept of a multichannel random decrement technique （MCRD）. This technique is based on extracting simultaneous random decrement records from measurements made at several points on the structure. The method is very efficient and simple. Numerical examples are solved and compared with the exact mode shapes extracted using classical modal analysis. An excellent agreement between the extracted modes shapes using the MCRD and those obtained from the classical modal analysis techniques is achieved. The vibration of an offshore structure excited by white noise excitation is used to illustrate the method.展开更多
The widespread application of photodetectors has triggered an urgent need for high-sensitivity and polarization-dependent photodetection.In this field,the two-dimensional(2D)tungsten disulfide(WS_(2))exhibits intrigui...The widespread application of photodetectors has triggered an urgent need for high-sensitivity and polarization-dependent photodetection.In this field,the two-dimensional(2D)tungsten disulfide(WS_(2))exhibits intriguing optical and electronic properties,making it an attractive photosensitive material for optoelectronic applications.However,the lack of an effective built-in electric field and photoconductive gain mechanism in 2D WS_(2)impedes its application in high-performance photodetectors.Herein,we propose a hybrid heterostructure photodetector that contains 1D Te and 2D WS_(2).In this device,1D Te induces in-plane strain in 2D WS_(2),which regulates the electronic structures of local WS_(2)and gives rise to type-Ⅱ band alignment in the horizontal direction.Moreover,the vertical heterojunction built of 2D WS_(2)and 1D Te introduces a high photoconductive gain.Benefiting from these two effects,the transfer of photogenerated carriers is optimized,and the proposed photodetector exhibits high sensitivity(photoresponsivity of ~27.7 A W^(-1),detectivity of 9.5×10^(12)Jones,and short rise/decay time of 19.3/17.6 ms).In addition,anisotropic photodetection characteristics with a dichroic ratio up to 2.1 are achieved.This hybrid 1D/2D heterostructure overcomes the inherent limitations of each material and realizes novel properties,opening up a new avenue towards constructing multifunctional optoelectronic devices.展开更多
基金Projects(51664017,51964015)supported by the National Natural Science Foundation of ChinaProject(JXUSTQJBJ2017007)supported by the Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology,ChinaProjects(GJJ160616,GJJ171490)supported by Science and Technology Project of Jiangxi Provincial Department of Education,China
文摘A wave equation of rock under axial static stress is established using the equivalent medium method by modifying the Kelvin-Voigt model.The analytical formulas of longitudinal velocity,space and time attenuation coefficients and response frequency are obtained by solving the equation using the harmonic method.A series of experiments on stress wave propagation through rock under different axial static stresses have been conducted.The proposed models of stress wave propagation are then verified by comparing experimental results with theoretical solutions.Based on the verified theoretical models,the influences of axial static stress on longitudinal velocity,space and time attenuation coefficients and response frequency are investigated by detailed parametric studies.The results show that the proposed theoretical models can be used to effectively investigate the effects of axial static stress on the stress wave propagation in rock.The axial static stress influences stress wave propagation characteristics of porous rock by varying the level of rock porosity and damage.Moreover,the initial porosity,initial elastic modulus of the rock voids and skeleton,viscous coefficient and vibration frequency have significant effects on the P-wave velocity,attenuation characteristics and response frequency of the stress wave in porous rock under axial static stress.
基金Science and Technology Commission ofYunnan Province(2006SG01),China
文摘Based on digital seismograms recorded by 11 stations of the Xiaowan Reservoir-induced Earthquake Monitoring Network from May 21,2005 to September 2006,we calculated the inelastic attenuation near Xiaowan reservoir using Atkinson method.We got the relation of Q value to frequency as Q(f)=225.8 f 0.332.Using the Moya method we got the site response of the 11 stations of Xiaowan Network and source parameters of 43 earthquakes.The source parameters were discussed briefly.
文摘The random decrement technique is an averaging technique that can be used to extract the free decay response of the structure from its random stationary vibratory response. The free decay response can then be used to identify the vibratory characteristics of the structure. The main advantage of the technique is that the identification of the parameters of the structure is achieved without previous knowledge of the excitation forces. This paper extends the random decrement technique to obtain the mode shapes of the structure using the concept of a multichannel random decrement technique （MCRD）. This technique is based on extracting simultaneous random decrement records from measurements made at several points on the structure. The method is very efficient and simple. Numerical examples are solved and compared with the exact mode shapes extracted using classical modal analysis. An excellent agreement between the extracted modes shapes using the MCRD and those obtained from the classical modal analysis techniques is achieved. The vibration of an offshore structure excited by white noise excitation is used to illustrate the method.
基金supported by the National Natural Science Foundation of China(61805044,62004071 and 11674310)the Key Platforms and Research Projects of Department of Education of Guangdong Province(2018KTSCX050)+1 种基金Guangdong Provincial Key Laboratory of Information Photonics Technology(2020B121201011)"The Pearl River Talent Recruitment Program"(2019ZT08X639)。
文摘The widespread application of photodetectors has triggered an urgent need for high-sensitivity and polarization-dependent photodetection.In this field,the two-dimensional(2D)tungsten disulfide(WS_(2))exhibits intriguing optical and electronic properties,making it an attractive photosensitive material for optoelectronic applications.However,the lack of an effective built-in electric field and photoconductive gain mechanism in 2D WS_(2)impedes its application in high-performance photodetectors.Herein,we propose a hybrid heterostructure photodetector that contains 1D Te and 2D WS_(2).In this device,1D Te induces in-plane strain in 2D WS_(2),which regulates the electronic structures of local WS_(2)and gives rise to type-Ⅱ band alignment in the horizontal direction.Moreover,the vertical heterojunction built of 2D WS_(2)and 1D Te introduces a high photoconductive gain.Benefiting from these two effects,the transfer of photogenerated carriers is optimized,and the proposed photodetector exhibits high sensitivity(photoresponsivity of ~27.7 A W^(-1),detectivity of 9.5×10^(12)Jones,and short rise/decay time of 19.3/17.6 ms).In addition,anisotropic photodetection characteristics with a dichroic ratio up to 2.1 are achieved.This hybrid 1D/2D heterostructure overcomes the inherent limitations of each material and realizes novel properties,opening up a new avenue towards constructing multifunctional optoelectronic devices.
