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Single-station microtremor surveys for site characterization:A case study in Erzurum city,eastern Turkey
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作者 Fatih Karsli Erdem Bayrak 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第3期563-576,共14页
The single-station microtremor method is one of the fastest,most reliable,and cheapest methods used to identify dynamic soil properties.This study utilizes 49 single-station microtremor measurements to identify the dy... The single-station microtremor method is one of the fastest,most reliable,and cheapest methods used to identify dynamic soil properties.This study utilizes 49 single-station microtremor measurements to identify the dynamic soil properties of the Hilalkent quarter of the Yakutiye district in Erzurum.Soil dominant frequency and the amplification factor were calculated by using the Nakamura horizontal/vertical spectral ratio(H/V)method.While the soil dominant frequency values varied between 0.4 Hz and 10 Hz,the soil amplification factor changed between 1 and 10.Higher H/V values were acquired with lower frequency values.The vulnerability index(K_(g))and shear strain parameters that are utilized to estimate the damage that may be caused by an earthquake were mapped.Especially in the west side of the study area,higher K_(g) values were observed.The shear strain map was created with 0.25 g,0.50 g and 0.75 g bedrock accelerations,and soil types that lost elasticity during an earthquake were identified.The average shear wave velocity for the first 30 m(V_(s30))was calculated.Finally,it was observed that the western part of the study area,which resulted in a higher period and higher H/V,higher K_(g) and lower V_(s30) values,presents a higher risk of damage during an earthquake. 展开更多
关键词 Nakamura horizontal/vertical spectral ratio single-station microtremor predominant frequency vulnerability index Erzurum
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Electromagnetic response function for the semi-annual variations estimated by the single-station method using the night-time values of the geomagnetic fields
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作者 陈伯舫 《Acta Seismologica Sinica(English Edition)》 CSCD 2000年第3期316-324,共9页
The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estim... The geomagnetic night-time values were used to estimate the electromagnetic response function Q1 for half-year period. If the spatial structure of the source field can be described by the approximation, one can estimate the Q1 value using the single-station Z/H method. This technique enables us to carry out regional deep gcomagnetic sounding by the method. The data used for analyses are geomagnetic night-time values for about, typically, 26 years from 5 good-quality stations and for several years from 34 stations distributed over the globe. The results indicate that the night-time values yield more reliable response estimates for half-year period compared to the usual estimates obtained from daily means. It implies that the approximation for the night-time fields holds good for the half-year period, but the daily means are not suitable for estimating the response function of the semi-annual variations by using the single-station method. Source field analyses for daily means data and night-time means data have also been carried out in this paper. 展开更多
关键词 geomagnetic night-time data semi-annual variations electromagnetic response functions single-station Z/H method
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EQGraphNet:Advancing single-station earthquake magnitude estimation via deep graph networks with residual connections
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作者 Zhiguo Wang Ziwei Chen Huai Zhang 《Artificial Intelligence in Geosciences》 2024年第1期257-268,共12页
Magnitude estimation is a critical task in seismology,and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution.In this context,we propose the Ea... Magnitude estimation is a critical task in seismology,and conventional methods usually require dense seismic station arrays to provide data with sufficient spatiotemporal distribution.In this context,we propose the Earthquake Graph Network(EQGraphNet)to enhance the performance of single-station magnitude estimation.The backbone of the proposed model consists of eleven convolutional neural network layers and ten RCGL modules,where a RCGL combines a Residual Connection and a Graph convolutional Layer capable of mitigating the over-smoothing problem and simultaneously extracting temporal features of seismic signals.Our work uses the STanford EArthquake Dataset for model training and performance testing.Compared with three existing deep learning models,EQGraphNet demonstrates improved accuracy for both local magnitude and duration magnitude scales.To evaluate the robustness,we add natural background noise to the model input and find that EQGraphNet achieves the best results,particularly for signals with lower signal-to-noise ratios.Additionally,by replacing various network components and comparing their estimation performances,we illustrate the contribution of each part of EQGraphNet,validating the rationality of our approach.We also demonstrate the generalization capability of our model across different earthquakes occurring environments,achieving mean errors of±0.1 units.Furthermore,by demonstrating the effectiveness of deeper architectures,this work encourages further exploration of deeper GNN models for both multi-station and single-station magnitude estimation. 展开更多
关键词 Magnitude estimation Graph neural network Symmetric graph single-station seismic signals
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Extraction of Alpha transmitter signals from single-station observations using the direction-finding method 被引量:2
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作者 GU XuDong CHEN Huan +4 位作者 WANG ShiWei LU ZiLong NI BinBin LI GuangJian CHENG Wen 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2022年第8期1727-1737,共11页
For the applications of Alpha very-low-frequency(VLF) systems consisting of multiple transmitters, determining the origin transmitter station of received signals is a crucial problem. Based on single-station observati... For the applications of Alpha very-low-frequency(VLF) systems consisting of multiple transmitters, determining the origin transmitter station of received signals is a crucial problem. Based on single-station observations, this study develops a directionfinding method to extract Russian Alpha transmitter signals. First, the amplitudes of Alpha signals received in Suizhou City,Hubei Province(31.57°N, 113.32°E) in the east-west(EW) and north-south(NS) directions are obtained by the power spectrum method. The amplitude ratios of signals in the two directions are subsequently adopted to estimate the propagation angles of the signals with respect to the NS direction of the VLF receiver station. Phase ambiguity in our system is eliminated by comparing Alpha signal waveform with that from the VTX transmitter in India(8.39°N, 77.75°E) as a reference station. Finally, we can determine the quadrant where the incoming wave signals are located relative to the receiver and eventually distinguish the exact Alpha transmitters. Based on the direction-finding results, the amplitudes of each Alpha signal are extracted, and their diurnal variation features are analyzed to verify the performance of our method. These results are of great significance for the further study of Alpha signals and VLF long-distance communication. 展开更多
关键词 very low frequency signal alpha transmitter direction-finding method single-station observation
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A new method of discovering new meteor showers from the IMO single-station video meteor database
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作者 LI Jun1,2 & ZHU Jin3 1 No.2 Middle School of Beijing,Beijing 100010,China 2 School of Journalism and Communication,Tsinghua University,Beijing 100084,China 3 Beijing Planterium,Beijing 100044,China 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2008年第8期1170-1178,共9页
It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization(IMO) by assuming the geocentric velocity and adjusti... It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization(IMO) by assuming the geocentric velocity and adjusting it within the dynamically permitted range. The mean geocentric velocities of new meteor showers can be obtained,as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All single station video meteor observations between February 13 and 17(from 2000 to 2005) in IMO's database are processed with this method. As a result,two new meteor showers,one near RA=245.10°,Dec=41.82° in Hercules and the other near RA=233.03°,Dec=17.04° in Serpenids,are discovered. Some dynamical characteristics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work,it is expected that there are some more potential new meteor showers in IMO's video database. 展开更多
关键词 single-station VIDEO METEOR DATABASE the process of single-station VIDEO METEOR DATABASE discovery of NEW METEOR showers
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A Modified-Simplified MPPT Technique for Three-Phase Single-State Grid-Connected PV Systems
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作者 Anuchit Aurairat Boonyang Plangklang 《Computers, Materials & Continua》 SCIE EI 2022年第8期2375-2395,共21页
Nowadays,the single state inverter for the grid-connected photovoltaic(PV)systems is becoming more and more popular as they can reduce circuit complexity resulting in less power losses of the inverter.This paper focus... Nowadays,the single state inverter for the grid-connected photovoltaic(PV)systems is becoming more and more popular as they can reduce circuit complexity resulting in less power losses of the inverter.This paper focuses on the use of model predictive control(MPC)to control a 3-phase and 2-level single-state grid-connected inverter in order to regulate the PV maximum power point(MPP).The algorithm of MPC scheme was done to measure the simultaneous current signal including predicting the next sampling current flow.The reference current(Id∗)was used to control the distribution of electrical power from the solar cell to the grid.To be able to control the maximum power point tracking(MPPT)when the sunlight suddenly changes,so that a developing MPPT based on estimation current perturbation and observation(ECP&O-MPPT)technique was used to control the reference current.This concept was experimented by using MATLAB/Simulink software package.The proposed technique was tested and compared with the old technique.The simulation results showed that the developed MPPT technique can track the MPP faster when the light changes rapidly under 1,000W/m2,25℃ standard climatic conditions.The MPPT time was 0.015 s.The total harmonic distortion(THD)was 2.17%and the power factor was 1. 展开更多
关键词 single-state grid-connected model predictive control maximum power point estimation perturbation and observation
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Comparative Study on Torque Performance of Five-phase Single-Stator and Double-Stator Permanent Magnet Synchronous Motors
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作者 Jing Zhao You Wang +1 位作者 Jingqi Li Hengzai Hu 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第1期46-52,共7页
This paper compares the torque characteristics of single stator permanent magnet synchronous motor(PMSM)and double-stator PMSM under different split-ratios,air-gap lengths and shaft diameters by finite element method.... This paper compares the torque characteristics of single stator permanent magnet synchronous motor(PMSM)and double-stator PMSM under different split-ratios,air-gap lengths and shaft diameters by finite element method.Firstly,the effects of split-ratio towards the torque characteristics of the two motor structures under different air-gap lengths are researched,the results show that the optimal split-ratios of the two motor structures do not change under different air-gap lengths,and the optimal split-ratio of the double-stator motor is greater than that of single-stator,and the torque of the double-stator motor is greater than that of single-stator motor with arbitrary split-ratio under the same air-gap length;Finally,the effects of the shaft diameter to the torque of the two motor structures are investigated,obtaining that with the increasing of shaft diameter,the electromagnetic torque of the single-stator motor is almost unchanged,however,the torque of the double-stator is gradually reduced,when the shaft diameter reached a certain extent,the electromagnetic torque of the double-stator motor is smaller than that of single-stator motor with the split ratio within a certain range,and the torque/quality ratio of the double-stator motor is smaller than that of single-stator motor with their optimal split ratio separately. 展开更多
关键词 Five-phase PMSM DOUBLE-STATOR single-stator split ratio electromagnetic torque
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Status of UnDifferenced and Uncombined GNSS Data Processing Activities in China
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作者 Pengyu HOU Delu CHE +3 位作者 Teng LIU Jiuping ZHA Yunbin YUAN Baocheng ZHANG 《Journal of Geodesy and Geoinformation Science》 CSCD 2023年第3期135-144,共10页
With the continued development of multiple Global Navigation Satellite Systems(GNSS)and the emergence of various frequencies,UnDifferenced and UnCombined(UDUC)data processing has become an increasingly attractive opti... With the continued development of multiple Global Navigation Satellite Systems(GNSS)and the emergence of various frequencies,UnDifferenced and UnCombined(UDUC)data processing has become an increasingly attractive option.In this contribution,we provide an overview of the current status of UDUC GNSS data processing activities in China.These activities encompass the formulation of Precise Point Positioning(PPP)models and PPP-Real-Time Kinematic(PPP-RTK)models for processing single-station and multi-station GNSS data,respectively.Regarding single-station data processing,we discuss the advancements in PPP models,particularly the extension from a single system to multiple systems,and from dual frequencies to single and multiple frequencies.Additionally,we introduce the modified PPP model,which accounts for the time variation of receiver code biases,a departure from the conventional PPP model that typically assumes these biases to be time-constant.In the realm of multi-station PPP-RTK data processing,we introduce the ionosphere-weighted PPP-RTK model,which enhances the model strength by considering the spatial correlation of ionospheric delays.We also review the phase-only PPP-RTK model,designed to mitigate the impact of unmodelled code-related errors.Furthermore,we explore GLONASS PPP-RTK,achieved through the application of the integer-estimable model.For large-scale network data processing,we introduce the all-in-view PPP-RTK model,which alleviates the strict common-view requirement at all receivers.Moreover,we present the decentralized PPP-RTK data processing strategy,designed to improve computational efficiency.Overall,this work highlights the various advancements in UDUC GNSS data processing,providing insights into the state-of-the-art techniques employed in China to achieve precise GNSS applications. 展开更多
关键词 Global Navigation Satellite Systems(GNSS) UnDifferenced and UnCombined(UDUC) Precise Point Positioning(PPP) PPP-Real-Time Kinematic(PPP-RTK) single-station data processing multi-station data processing
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Investigations of the seismomagnetic effect in the geomagnetic diurnal variations
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作者 陈伯舫 《Acta Seismologica Sinica(English Edition)》 CSCD 1994年第3期457-464,共8页
In this paper we attempt to Abstract seismomagnetic signals from geomagnetic diurnal variations of three components in quiet days before and after great earthquakes. The method employed here is to examine the ratio of... In this paper we attempt to Abstract seismomagnetic signals from geomagnetic diurnal variations of three components in quiet days before and after great earthquakes. The method employed here is to examine the ratio of apparent depths between two geomagnetic observatories using the single-station Z/H method. We first estimate the apparent depth for the period of 24 h for two observatories which are located at almost the same latitude. Then we analyse the time changes of the apparent-depth-ratio between these stations. In the interval of 1962 1988, the time variation of apparent-depth-ratio between the Beijing and Lanzhou observatories seems to be related to the three great earthquakes occurred near Beijing. Roughly speaking, the anomalous change in apparentdepth-ratio appears to be positive before earthquake, and appears to be negative after earthquake. 展开更多
关键词 geomagnetic S_q field single-station Z/H method deep conductivily seismomagnetic effect
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Structural total least squares algorithm for locating multiple disjoint sources based on AOA/TOA/FOA in the presence of system error 被引量:7
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作者 Xin CHEN Ding WANG +2 位作者 Rui-rui LIU Jie-xin YIN Ying WU 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2018年第7期917-936,共20页
Single-station passive localization technology avoids the complex time synchronization and information exchange between multiple observatories, and is increasingly important in electronic warfare. Based on a single mo... Single-station passive localization technology avoids the complex time synchronization and information exchange between multiple observatories, and is increasingly important in electronic warfare. Based on a single moving station localization system, a new method with high localization precision and numerical stability is proposed when the measurements from multiple disjoint sources are subject to the same station position and velocity displacement. According to the available measurements including the angle-of-arrival(AOA), time-of-arrival(TOA), and frequency-of-arrival(FOA), the corresponding pseudo linear equations are deduced. Based on this, a structural total least squares(STLS) optimization model is developed and the inverse iteration algorithm is used to obtain the stationary target location. The localization performance of the STLS localization algorithm is derived, and it is strictly proved that the theoretical performance of the STLS method is consistent with that of the constrained total least squares method under first-order error analysis, both of which can achieve the Cramér-Rao lower bound accuracy. Simulation results show the validity of the theoretical derivation and superiority of the new algorithm. 展开更多
关键词 single-station Structural total least squares Inverse iteration Angle-of-arrival (AOA) Time-of-arrival (TOA) Frequency-of-arrival (FOA) Disjoint sources
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