Gas hydrate drilling expeditions in the Pearl River Mouth Basin,South China Sea,have identified concentrated gas hydrates with variable thickness.Moreover,free gas and the coexistence of gas hydrate and free gas have ...Gas hydrate drilling expeditions in the Pearl River Mouth Basin,South China Sea,have identified concentrated gas hydrates with variable thickness.Moreover,free gas and the coexistence of gas hydrate and free gas have been confirmed by logging,coring,and production tests in the foraminifera-rich silty sediments with complex bottom-simulating reflectors(BSRs).The broad-band processing is conducted on conventional three-dimensional(3D)seismic data to improve the image and detection accuracy of gas hydratebearing layers and delineate the saturation and thickness of gas hydrate-and free gas-bearing sediments.Several geophysical attributes extracted along the base of the gas hydrate stability zone are used to demonstrate the variable distribution and the controlling factors for the differential enrichment of gas hydrate.The inverted gas hydrate saturation at the production zone is over 40% with a thickness of 90 m,showing the interbedded distribution with different boundaries between gas hydrate-and free gas-bearing layers.However,the gas hydrate saturation value at the adjacent canyon is 70%,with 30-m-thick patches and linear features.The lithological and fault controls on gas hydrate and free gas distributions are demonstrated by tracing each gas hydrate-bearing layer.Moreover,the BSR depths based on broad-band reprocessed 3D seismic data not only exhibit variations due to small-scale topographic changes caused by seafloor sedimentation and erosion but also show the upward shift of BSR and the blocky distribution of the coexistence of gas hydrate and free gas in the Pearl River Mouth Basin.展开更多
In order to improve the bandwidth of the conventional sub-harmonic mixer, a broad-band, high intermediate frequency（IF） sub-harmonic mixer for W-band applications is proposed. Replacing the open and short stubs that...In order to improve the bandwidth of the conventional sub-harmonic mixer, a broad-band, high intermediate frequency（IF） sub-harmonic mixer for W-band applications is proposed. Replacing the open and short stubs that are used in the convertional sub-harmonic mixer with a broad-band band-pass filter and a low-pass filter, respectively, a wide operating frequency band is achieved. Furthermore, without the use of the edge-coupled band-pass filter at radio frequency（RF） port, the proposed structure can be realized by common hybrid microwave integrated circuit technology at W- band. The measured results show that the proposed subharmonic mixer can operate from 80 to 107.5 GHz for RF frequency and support up to 18 GHz for the IF bandwidth. Also, the measured results show that the single-sideband conversion loss is less than 13. 7 dB over the available RF frequency band, while the minimum conversion loss is about 9 dB at an RF of 92. 5 GHz and an 1F of 3 GHz. Thus, a large operating bandwidth performance at W-band can be achieved by the orooosed mixer.展开更多
Regionalized location accuracy of the China National Seismograph Network was estimated using the results obtained by studying “repeating earthquakes" or “doublets" in and around China by Schaff and Richard...Regionalized location accuracy of the China National Seismograph Network was estimated using the results obtained by studying “repeating earthquakes" or “doublets" in and around China by Schaff and Richards (2004). It is assumed that the “repeating events" or “doublets" are separated by no more than 1km, and the network measured apparent distance X of “doublets" indicates the order of magnitudes of the location error. It is observed that the average location accuracy of the China National Seismograph Network, as represented by average X value, is in the order of magnitudes of 10km, and is larger in the Qinghai-Xizang (Tibet) Plateau, western and northern Xinjiang, and eastern Inner Mongolia.展开更多
We introduce in this paper a method to calculate response spectra of earthquake ground motion from seismograms of Type 513 seismograph. The seismograms of two horizontal components of the M s 7.1 earthquake, an a...We introduce in this paper a method to calculate response spectra of earthquake ground motion from seismograms of Type 513 seismograph. The seismograms of two horizontal components of the M s 7.1 earthquake, an aftershock of 1976 M S=7.8 Tangshan earthquake, recorded by type 513 seismograph in Taian station are used as an example. After curve digitization, arc shape curve correction, equal distance interpolation and instrument response correction, the absolute acceleration response spectra, relative velocity response spectra and relative displacement response spectra of different damping ratios in the period range of T ≤10 s are calculated in frequency domain.展开更多
According to different testing purposes, methods and available environmental conditions, the seismograph testing can be divided into laboratory and on-site testing, respectively. The testing of the seismograph's k...According to different testing purposes, methods and available environmental conditions, the seismograph testing can be divided into laboratory and on-site testing, respectively. The testing of the seismograph's key parameters and other concerning technical specifications are well described in guide documents(China Earthquake Administration, 2017). This includes seismometer sensitivity, linearity and clip levels based on the shake table test, as well as the seismometer natural period, damping constant based on electrical calibration(Wang Guangfu,1986; Ple?inger A.,1993) and instrumental self-noise collocation estimation(Holcomb L.G., 1989; Sleeman R. et al., 2006). However, with the development of seismic observation technology, many new requirements for the performance evaluation of seismographs have been put forward, and new testing items and methods have emerged.展开更多
In order to eliminate chaotic oscillation of electromechanical characteristics of seismograph system, the complex dynamic the four-dimensional nonlinear equations of seismograph system were analyzed. Sliding mode meth...In order to eliminate chaotic oscillation of electromechanical characteristics of seismograph system, the complex dynamic the four-dimensional nonlinear equations of seismograph system were analyzed. Sliding mode method was applied to stabilize the chaotic orbits of the eleetromechanieal seismograph system to arbitrary chosen fixed points and periodic orbits precisely, and MATLAB simulations were presented to confirm the validity of the controller. The results show that using sliding mode method can make the system track target orbit strictly and smoothly with short transition time, and its insensitivity to noise disturbances is shown. It also provides reference for relevant chaos control in relevant system.展开更多
Broad-band all-optical wavelength conversion of differential phase-shift keyed （DPSK） signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a...Broad-band all-optical wavelength conversion of differential phase-shift keyed （DPSK） signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a semiconductor optical amplifier （SOA） based nonlinear polarization switch. A wavelength converter for the 10 G b/s DPSK signal is presented, which has a wide wavelength range of more than 30 nm. The converted signals experience small power penalties less than 1.4 dB compared with the original signal, at a bit error rate of 10-9. Additionally, the optical spectra, the measured waveforms and the open eye diagrams of the converted signals show a high quality wavelength conversion performance.展开更多
The authors proposed a method for obtaining high-quality acceleration seismograms from velocity type seismograms of digital Seismographic network, and took as an example the analysis and processing of the seismograms ...The authors proposed a method for obtaining high-quality acceleration seismograms from velocity type seismograms of digital Seismographic network, and took as an example the analysis and processing of the seismograms of a same earthquake that was simultaneously recorded by velocity seismograph CTS1-EDAS24 and strong motion seismograph EST-Q4128 installed in Jixian Station, Tianjin. The calculation steps and the processing method have been discussed in detail. From the analysis and the comparison of the obtained results, it is concluded that the proposed method is simple and effective, and it broadens the application of digital seismographic network.展开更多
The low Gilbert damping factor, which is usually measured by ferromagnetic resonance, is crucial in spintronic applications. Two-magnon scattering occurs when the orthogonMity of the ferromagnetic resonance mode and o...The low Gilbert damping factor, which is usually measured by ferromagnetic resonance, is crucial in spintronic applications. Two-magnon scattering occurs when the orthogonMity of the ferromagnetic resonance mode and other degenerate spin wave modes was broken by magnetic anisotropy, voids, second phase, surface defects, etc., which is important in analysis of ferromagnetic resonance linewidth. Direct fitting to linewidth with Gilbert damping is advisable only when the measured linewidth is a linear function of measuring frequency in a broad band measurement. We observe the nonlinear ferromagnetic resonance linewidth of Co2MnSi thin films with respect to measuring frequency in broad band measurement. Experimental data could be well fitted with the model including two-magnon scattering with no fixed parameters. The fitting results show that two-magnon scattering results in the nonlinear linewidth behavior, and the Gilbert damping factor is much smaller than reported ones, indicating that our Co2MnSi films are more suitable for the applications of spin transfer torque.展开更多
Criminal law involves crucial rights of the public,including property rights,political rights,freedom,and even life.As a result,on the one hand,any change to the rule by criminal law may have a significant impact on p...Criminal law involves crucial rights of the public,including property rights,political rights,freedom,and even life.As a result,on the one hand,any change to the rule by criminal law may have a significant impact on people’s lives;on the other hand,any change to the rule by criminal law is a highly sensitive issue.In view of these points,the rule by criminal law is often referred to as the seismograph for the protection of human rights,indicating the utmost importance of rule by criminal law展开更多
The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola...The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola software was used to estimate the CMT solution by selecting the velocity model that best suited the local and regional geological conditions in Indonesia and the surrounding areas.The data used in this study were earthquakes with magnitudes of 5.4 to 8.0.High-quality,real-time broadband seismographic data were provided by the International Federation of Digital Seismograph Networks Web Services(FDSNWS)and the European Integrated Data Archive(EIDA)Federation in Indonesia and the surrounding areas.Furthermore,the inversion process and filter adjustment were carried out on the seismographic data to obtain good CMT solutions.The CMT solutions from Gisola provided good-quality solutions,in which all earthquake data had A-level quality(high quality,with good variant reduction).The Gisola CMT solution was justified with the Global CMT(GCMT)solution by using the Kagan angle value,with an average of approximately 11.2°.This result suggested that the CMT solution generated from Gisola was trustworthy and reliable.The Gisola CMT solution was typically available within approximately 15 minutes after an earthquake occurred.Once it met the quality requirement,it was automatically published on the internet.The catalog of local and regional earthquake records obtained through this technology holds great promise for improving the current understanding of regional seismic activity and ongoing tectonic processes.The accurate and real-time CMT solution generated by implementing the Gisola algorithm consisted of moment tensors and moment magnitudes,which provided invaluable insights into earthquakes occurring in Indonesia and the surrounding areas.展开更多
The seismological observation system in China has experienced rapid development over the Tenth Five-year Plan period. China Earthquake Administration (CEA) has completed the establishment of China digital seismologica...The seismological observation system in China has experienced rapid development over the Tenth Five-year Plan period. China Earthquake Administration (CEA) has completed the establishment of China digital seismological observation network. CEA has accomplished analog-to-digital conversion of the existing seismological observation systems and set up a number of new digital seismic stations. This indicates full digitization of seismological ob-servation in China. This paper presents an overview of the scale,layout principle and major functions of the up-dated national digital seismograph network,regional digital seismograph network,and digital seismograph net-work for volcano monitoring and mobile digital seismograph networks in China.展开更多
基金supported by the State Key Laboratory of Natural Gas Hydrate(No.2022-KFJJ-SHW)the National Natural Science Foundation of China(No.42376058)+2 种基金the International Science&Technology Cooperation Program of China(No.2023YFE0119900)the Hainan Province Key Research and Development Project(No.ZDYF2024GXJS002)the Research Start-Up Funds of Zhufeng Scholars Program.
文摘Gas hydrate drilling expeditions in the Pearl River Mouth Basin,South China Sea,have identified concentrated gas hydrates with variable thickness.Moreover,free gas and the coexistence of gas hydrate and free gas have been confirmed by logging,coring,and production tests in the foraminifera-rich silty sediments with complex bottom-simulating reflectors(BSRs).The broad-band processing is conducted on conventional three-dimensional(3D)seismic data to improve the image and detection accuracy of gas hydratebearing layers and delineate the saturation and thickness of gas hydrate-and free gas-bearing sediments.Several geophysical attributes extracted along the base of the gas hydrate stability zone are used to demonstrate the variable distribution and the controlling factors for the differential enrichment of gas hydrate.The inverted gas hydrate saturation at the production zone is over 40% with a thickness of 90 m,showing the interbedded distribution with different boundaries between gas hydrate-and free gas-bearing layers.However,the gas hydrate saturation value at the adjacent canyon is 70%,with 30-m-thick patches and linear features.The lithological and fault controls on gas hydrate and free gas distributions are demonstrated by tracing each gas hydrate-bearing layer.Moreover,the BSR depths based on broad-band reprocessed 3D seismic data not only exhibit variations due to small-scale topographic changes caused by seafloor sedimentation and erosion but also show the upward shift of BSR and the blocky distribution of the coexistence of gas hydrate and free gas in the Pearl River Mouth Basin.
基金Research Foundation of China ( No.9140A01020209JW0601)
文摘In order to improve the bandwidth of the conventional sub-harmonic mixer, a broad-band, high intermediate frequency（IF） sub-harmonic mixer for W-band applications is proposed. Replacing the open and short stubs that are used in the convertional sub-harmonic mixer with a broad-band band-pass filter and a low-pass filter, respectively, a wide operating frequency band is achieved. Furthermore, without the use of the edge-coupled band-pass filter at radio frequency（RF） port, the proposed structure can be realized by common hybrid microwave integrated circuit technology at W- band. The measured results show that the proposed subharmonic mixer can operate from 80 to 107.5 GHz for RF frequency and support up to 18 GHz for the IF bandwidth. Also, the measured results show that the single-sideband conversion loss is less than 13. 7 dB over the available RF frequency band, while the minimum conversion loss is about 9 dB at an RF of 92. 5 GHz and an 1F of 3 GHz. Thus, a large operating bandwidth performance at W-band can be achieved by the orooosed mixer.
文摘Regionalized location accuracy of the China National Seismograph Network was estimated using the results obtained by studying “repeating earthquakes" or “doublets" in and around China by Schaff and Richards (2004). It is assumed that the “repeating events" or “doublets" are separated by no more than 1km, and the network measured apparent distance X of “doublets" indicates the order of magnitudes of the location error. It is observed that the average location accuracy of the China National Seismograph Network, as represented by average X value, is in the order of magnitudes of 10km, and is larger in the Qinghai-Xizang (Tibet) Plateau, western and northern Xinjiang, and eastern Inner Mongolia.
文摘We introduce in this paper a method to calculate response spectra of earthquake ground motion from seismograms of Type 513 seismograph. The seismograms of two horizontal components of the M s 7.1 earthquake, an aftershock of 1976 M S=7.8 Tangshan earthquake, recorded by type 513 seismograph in Taian station are used as an example. After curve digitization, arc shape curve correction, equal distance interpolation and instrument response correction, the absolute acceleration response spectra, relative velocity response spectra and relative displacement response spectra of different damping ratios in the period range of T ≤10 s are calculated in frequency domain.
基金sponsored by the Department of Earthquake Monitoring and Prediction,China Earthquake Administration
文摘According to different testing purposes, methods and available environmental conditions, the seismograph testing can be divided into laboratory and on-site testing, respectively. The testing of the seismograph's key parameters and other concerning technical specifications are well described in guide documents(China Earthquake Administration, 2017). This includes seismometer sensitivity, linearity and clip levels based on the shake table test, as well as the seismometer natural period, damping constant based on electrical calibration(Wang Guangfu,1986; Ple?inger A.,1993) and instrumental self-noise collocation estimation(Holcomb L.G., 1989; Sleeman R. et al., 2006). However, with the development of seismic observation technology, many new requirements for the performance evaluation of seismographs have been put forward, and new testing items and methods have emerged.
基金the Independent Research Project of State Key Laboratory of Power Transmission Equipment & System Security and New Technology,China ( No. 2007DA10512711205)
文摘In order to eliminate chaotic oscillation of electromechanical characteristics of seismograph system, the complex dynamic the four-dimensional nonlinear equations of seismograph system were analyzed. Sliding mode method was applied to stabilize the chaotic orbits of the eleetromechanieal seismograph system to arbitrary chosen fixed points and periodic orbits precisely, and MATLAB simulations were presented to confirm the validity of the controller. The results show that using sliding mode method can make the system track target orbit strictly and smoothly with short transition time, and its insensitivity to noise disturbances is shown. It also provides reference for relevant chaos control in relevant system.
文摘Broad-band all-optical wavelength conversion of differential phase-shift keyed （DPSK） signal is experimentally demonstrated. This scheme is composed of a one-bit delay interferometer demodulation stage followed by a semiconductor optical amplifier （SOA） based nonlinear polarization switch. A wavelength converter for the 10 G b/s DPSK signal is presented, which has a wide wavelength range of more than 30 nm. The converted signals experience small power penalties less than 1.4 dB compared with the original signal, at a bit error rate of 10-9. Additionally, the optical spectra, the measured waveforms and the open eye diagrams of the converted signals show a high quality wavelength conversion performance.
文摘The authors proposed a method for obtaining high-quality acceleration seismograms from velocity type seismograms of digital Seismographic network, and took as an example the analysis and processing of the seismograms of a same earthquake that was simultaneously recorded by velocity seismograph CTS1-EDAS24 and strong motion seismograph EST-Q4128 installed in Jixian Station, Tianjin. The calculation steps and the processing method have been discussed in detail. From the analysis and the comparison of the obtained results, it is concluded that the proposed method is simple and effective, and it broadens the application of digital seismographic network.
基金Supported by the National Basic Research Program of China under Grant No 2015CB921502the National Natural Science Foundation of China under Grant Nos 11474184 and 11174183+4 种基金the Program for New Century Excellent Talents of China under Grant No NCET-10-0541the Scientific Research Foundation for Returned Overseas Chinese Scholars under Grant No B13029the Natural Science Foundation of Shandong Province under Grant No JQ201201the Doctorate Foundation of Shandong Province under Grant No BS2013CL042the Young Scientists Fund of the National Natural Science Foundation of China under Grant No 11204164
文摘The low Gilbert damping factor, which is usually measured by ferromagnetic resonance, is crucial in spintronic applications. Two-magnon scattering occurs when the orthogonMity of the ferromagnetic resonance mode and other degenerate spin wave modes was broken by magnetic anisotropy, voids, second phase, surface defects, etc., which is important in analysis of ferromagnetic resonance linewidth. Direct fitting to linewidth with Gilbert damping is advisable only when the measured linewidth is a linear function of measuring frequency in a broad band measurement. We observe the nonlinear ferromagnetic resonance linewidth of Co2MnSi thin films with respect to measuring frequency in broad band measurement. Experimental data could be well fitted with the model including two-magnon scattering with no fixed parameters. The fitting results show that two-magnon scattering results in the nonlinear linewidth behavior, and the Gilbert damping factor is much smaller than reported ones, indicating that our Co2MnSi films are more suitable for the applications of spin transfer torque.
文摘Criminal law involves crucial rights of the public,including property rights,political rights,freedom,and even life.As a result,on the one hand,any change to the rule by criminal law may have a significant impact on people’s lives;on the other hand,any change to the rule by criminal law is a highly sensitive issue.In view of these points,the rule by criminal law is often referred to as the seismograph for the protection of human rights,indicating the utmost importance of rule by criminal law
基金Universitas Negeri Surabaya,Universitas Sebelas Maret,and Universitas Syiah Kuala for providing research grants for the Indonesian Collaborative Research(RKI)scheme。
文摘The purpose of this research was to suggest an applicable procedure for computing the centroid moment tensor(CMT)automatically and in real time from earthquakes that occur in Indonesia and the surrounding areas.Gisola software was used to estimate the CMT solution by selecting the velocity model that best suited the local and regional geological conditions in Indonesia and the surrounding areas.The data used in this study were earthquakes with magnitudes of 5.4 to 8.0.High-quality,real-time broadband seismographic data were provided by the International Federation of Digital Seismograph Networks Web Services(FDSNWS)and the European Integrated Data Archive(EIDA)Federation in Indonesia and the surrounding areas.Furthermore,the inversion process and filter adjustment were carried out on the seismographic data to obtain good CMT solutions.The CMT solutions from Gisola provided good-quality solutions,in which all earthquake data had A-level quality(high quality,with good variant reduction).The Gisola CMT solution was justified with the Global CMT(GCMT)solution by using the Kagan angle value,with an average of approximately 11.2°.This result suggested that the CMT solution generated from Gisola was trustworthy and reliable.The Gisola CMT solution was typically available within approximately 15 minutes after an earthquake occurred.Once it met the quality requirement,it was automatically published on the internet.The catalog of local and regional earthquake records obtained through this technology holds great promise for improving the current understanding of regional seismic activity and ongoing tectonic processes.The accurate and real-time CMT solution generated by implementing the Gisola algorithm consisted of moment tensors and moment magnitudes,which provided invaluable insights into earthquakes occurring in Indonesia and the surrounding areas.
文摘The seismological observation system in China has experienced rapid development over the Tenth Five-year Plan period. China Earthquake Administration (CEA) has completed the establishment of China digital seismological observation network. CEA has accomplished analog-to-digital conversion of the existing seismological observation systems and set up a number of new digital seismic stations. This indicates full digitization of seismological ob-servation in China. This paper presents an overview of the scale,layout principle and major functions of the up-dated national digital seismograph network,regional digital seismograph network,and digital seismograph net-work for volcano monitoring and mobile digital seismograph networks in China.
