High-vertical-resolution radiosonde wind data are highly valuable for describing the dynamics of the meso-and microscale atmosphere. However, the current algorithm used in China's L-band radar sounding system for ...High-vertical-resolution radiosonde wind data are highly valuable for describing the dynamics of the meso-and microscale atmosphere. However, the current algorithm used in China's L-band radar sounding system for calculating highvertical-resolution wind vectors excessively smooths the data, resulting in significant underestimation of the calculated kinetic energy of gravity waves compared to similar products from other countries, which greatly limits the effective utilization of the data. To address this issue, this study proposes a novel method to calculate high-vertical-resolution wind vectors that utilizes the elevation angle, azimuth angle, and slant range from L-band radar. In order to obtain wind data with a stable quality, a two-step automatic quality control procedure, including the RMSE-F(root-mean-square error F) test and elemental consistency test are first applied to the slant range data, to eliminate continuous erroneous data caused by unstable signals or radar malfunctions. Then, a wind calculation scheme based on a sliding second-order polynomial fitting is utilized to derive the high-vertical-resolution radiosonde wind vectors. The evaluation results demonstrate that the wind data obtained through the proposed method show a high level of consistency with the high-resolution wind data observed using the Vaisala Global Positioning System and the data observed by the new Beidou Navigation Sounding System. The calculation of the kinetic energy of gravity waves in the recalculated wind data also reaches a level comparable to the Vaisala observations.展开更多
With the development of wireless communication,the fifth generation mobile communication technology(5G)has emerged as a hot topic in highspeed railway communication system and has moved towards industrial application....With the development of wireless communication,the fifth generation mobile communication technology(5G)has emerged as a hot topic in highspeed railway communication system and has moved towards industrial application.Investigating the radio propagation characteristics in 5G high-speed train(HST)scenarios is essential for enhancing wireless coverage and overall system performance.We propose a novel 5G passive sounding scheme to extract channel impulse responses(CIRs)using channel state information reference signals(CSI-RS)from the target 5G base station(BS).Detailed procedures for timefrequency synchronization,CSI-RS detection and extraction are presented through simulations.Through the laboratory work involving absolute power calibration,phase coherence calibration and power delay profile(PDP)validation,we validate the accuracy and performance of the developed platform.Furthermore,a measurement campaign was conducted in HST scenarios encompassing both residential and undeveloped areas.The path loss(PL)model and the channel characteristics including stationarity interval(SI),multipath components(MPCs),shadow fading(SF),Rician K-factor,root mean square(RMS)delay spread and received correlation coefficients are analyzed and fitted.The estimated channel characteristics and the statistical model presented in this paper will contribute to the research on HST radio propagation and the development of 5G railway communication systems.展开更多
Introduction: Located in the central-western part of Côte d’Ivoire, the subsoil of the Gagnoa region is made up of sedimentary volcano formations and granitoids with developed fracturing. This complex Precambria...Introduction: Located in the central-western part of Côte d’Ivoire, the subsoil of the Gagnoa region is made up of sedimentary volcano formations and granitoids with developed fracturing. This complex Precambrian basement contains most of the region’s water resources. This is at the origin of the high failure rate during the various hydrogeological prospecting campaigns. Methodology: The database consists of resistivities from 42 holes and 51 trails drilled as part of the implementation of high-throughput drilling in the study area. The objective of this study is to deepen the knowledge of the fissured basement by interpreting profile curves and electrical soundings. It will be a question of classifying the different types of anomalies obtained on the profiles and their shapes. The orientation of the lineaments observed on the profiles was determined. Results: The interpretation of the geophysical data revealed various anomalies, the main ones being of the CC (Conductor Compartment) and CEDP (Contact between two bearings) types. These types of anomalies are mainly expressed in various forms: the “V”, “W” and “U” shapes. From these anomalies and the appearance of the electrical profiles, lineaments and their orientations were identified with N90-100, N130-140, N170-180 as major orientations. Conclusion: These results could contribute to a better understanding of the fractured environment of the Gagnoa region.展开更多
Shipboard radiosonde soundings are important for detecting and quantifying the multiscale variability of atmosphere-ocean interactions associated with mass exchanges.This study evaluated the accuracies of shipboard Gl...Shipboard radiosonde soundings are important for detecting and quantifying the multiscale variability of atmosphere-ocean interactions associated with mass exchanges.This study evaluated the accuracies of shipboard Global Positioning System(GPS)soundings in the eastern tropical Indian Ocean and South China Sea through a simultaneous balloon-borne inter-comparison of different radiosonde types.Our results indicate that the temperature and relative humidity(RH)measurements of GPS-TanKong(GPS-TK)radiosonde(used at most stations before 2012)have larger biases than those of ChangFeng-06-A(CF-06-A)radiosonde(widely used in current observation)when compared to reference data from Vaisala RS92-SGP radiosonde,with a warm bias of 5℃and dry bias of 10%during daytimes,and a cooling bias of-0.8℃and a moist bias of 6%during nighttime.These systematic biases are primarily attributed to the radiation effects and altitude deviation.An empirical correction algorithm was developed to retrieve the atmospheric temperature and RH profiles.The corrected profiles agree well with that of RS92-SGP,except for uncertainties of CF-06-A in the stratosphere.These correction algorithms were applied to the GPS-TK historical sounding records,reducing biases in the corrected temperature and RH profiles when compared to radio occultation data.The correction of GPS-TK historical records illustrated an improvement in capturing the marine atmospheric structure,with more accurate atmospheric boundary layer height,convective available potential energy,and convective inhibition in the tropical ocean.This study contributes significantly to improving the quality of GPS radiosonde soundings and promotes the sharing of observation in the eastern tropical Indian Ocean and South China Sea.展开更多
Based on L-band sounding data,threshold method of relative humidity was used to analyze vertical distribution characteristics of precipitation cloud system in Tianjin region.The results showed that main precipitation ...Based on L-band sounding data,threshold method of relative humidity was used to analyze vertical distribution characteristics of precipitation cloud system in Tianjin region.The results showed that main precipitation cloud system affecting Tianjin is cold and warm mixed cloud,followed by cold cloud,and precipitation of warm cloud is less.During May-November,precipitation of cold and warm mixed cloud is dominant,and it is dominant by precipitation of cold cloud from January to April.In four seasons,the precipitation frequency of double-layer cloud is the most,and precipitation of single-layer cloud mainly appears during March-November,and peak is in June.Peak of cloud system with three or more layers all appears in July and August.The cold cloud and warm cloud catalysts should be selected respectively for artificial precipitation enhancement in Tianjin.In winter,cold cloud catalyst operation is selected;in spring,summer and autumn,the cold cloud catalyst is spread in the cold cloud area,and the warm cloud catalyst is distributed in the warm cloud area according to the conditions of cloud layer.展开更多
[Objective] The research aimed to discuss shallowly the application of L-band sounding seconds data in the artificial precipitation. [Method] The characteristics, getting manner and displaying method of L-band soundin...[Objective] The research aimed to discuss shallowly the application of L-band sounding seconds data in the artificial precipitation. [Method] The characteristics, getting manner and displaying method of L-band sounding seconds data were introduced briefly. Moreover, its application prospect in the artificial precipitation operation was analyzed initially. We aimed to improve its application rate in the artificial precipitation operation. [Result] L-band sounding seconds data had the great improvement in the time-space resolution and the space positioning accuracy aspects when compared with the previous sounding data, and the precision reached the second level. It could provide the high-precision data basis for the assimilation of artificial precipitation numerical model initial field, and improve the numerical model. Moreover, the sounding product could provide the accurate scientific basis for the selection of artificial precipitation operation tool, the determination of operation height and range, and guide the artificial precipitation operation, and improve the operation efficiency. [Conclusion] The research provided the analysis and reference basis for the command of artificial precipitation operation.展开更多
The continuously available satellites of European Galileo currently reach more than 25.To explore the rationality and reliability of the L-band and satellite laser ranging(SLR)data processing strategies,we design the ...The continuously available satellites of European Galileo currently reach more than 25.To explore the rationality and reliability of the L-band and satellite laser ranging(SLR)data processing strategies,we design the Galileo L-band,the SLR-only,and the combined L-band/SLR dynamic precise orbit determination(POD)strategies by using the normal equations(NEQs)stacking,and investigate their continuity and stability by employing the Galileo L-band data and SLR observations for the time span of the whole year of 2023,based on the Bei Dou/GNSS analysis center platform of Shandong University by using the modified Bernese GNSS Software Version 5.4.The orbital consistency of the L-band 1-day solution is the best with the Three-dimensional Root-Mean-Square(3D-RMS)values of 3.6 cm compared with the Center for Orbit Determination in Europe Multi-GNSS Experiment(COM)orbits,the corresponding values is 1.4 cm,2.5 cm,and 2.3 cm in Radial,the Tangential,and the Normal(RTN)direction,respectively.While the SLR-only 9-day arc length is optimal with the RTN values of 5.3 cm,30 cm,and 38.2 cm,as well as the 3D-RMS values of 48.9 cm.Encouragingly,the difference of the orbital accuracy between the combined L-band/SLR multi-day solution and the COM orbits is reduced by 0.5 cm and 0.9 cm,0.6 cm and 1.2 cm in T-,and N-direction for the 3-and 5-day solution respectively.The corresponding values improve 0.7 cm and 0.9 cm,1.4 cm and 1.8 cm for the 3-and 5-day orbital overlaps difference between the combined L-band/SLR and the L-band solution.Take the E09 satellite as a case study,the SLR-only orbital accuracy is regularly optimized as the multi-day arc lengthens and with the sites increase.Furthermore,the SLR residuals of its three types of orbits further demonstrate the positive contribution of SLR to the combination of the GNSS and SLR techniques.展开更多
The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-...The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.展开更多
Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter...Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.展开更多
The ability to localize sound sources rapidly allows human beings to efficiently understand the surrounding environment.Previous studies have suggested that there is an auditory“where”pathway in the cortex for proce...The ability to localize sound sources rapidly allows human beings to efficiently understand the surrounding environment.Previous studies have suggested that there is an auditory“where”pathway in the cortex for processing sound locations.The neural activation in regions along this pathway encodes sound locations by opponent hemifield coding,in which each unilateral region is activated by sounds coming from the contralateral hemifield.However,it is still unclear how these regions interact with each other to form a unified representation of the auditory space.In the present study,we investigated whether functional connectivity in the auditory“where”pathway encoded sound locations during passive listening.Participants underwent functional magnetic resonance imaging while passively listening to sounds from five distinct horizontal locations(−90°,−45°,0°,45°,90°).We were able to decode sound locations from the functional connectivity patterns of the“where”pathway.Furthermore,we found that such neural representation of sound locations was primarily based on the coding of sound lateralization angles to the frontal midline.In addition,whole-brain analysis indicated that functional connectivity between occipital regions and the primary auditory cortex also encoded sound locations by lateralization angles.Overall,our results reveal a lateralization-angle-based representation of sound locations encoded by functional connectivity patterns,which could add on the activation-based opponent hemifield coding to provide a more precise representation of the auditory space.展开更多
A Wentzel-Kramers-Brillouin(WKB)method is introduced for obtaining a uniform asymptotic solution for underwater sound propagation at very low frequencies in deep ocean.The method utilizes a mode sum and employs the re...A Wentzel-Kramers-Brillouin(WKB)method is introduced for obtaining a uniform asymptotic solution for underwater sound propagation at very low frequencies in deep ocean.The method utilizes a mode sum and employs the reference functions method to describe the solution to the depth-separated wave equation approximately using parabolic cylinder functions.The conditions for the validity of this approximation are also discussed.Furthermore,a formula that incorporates waveguide effects for the modal group velocity is derived,revealing that boundary effects at very low frequencies can have a significant impact on the propagation characteristics of even low-order normal modes.The present method not only offers improved accuracy compared to the classical WKB approximation and the uniform asymptotic approximation based on Airy functions,but also provides a wider range of depth applicability.Additionally,this method exhibits strong agreement with numerical methods and offers valuable physical insights.Finally,the method is applied to the study of very-low-frequency sound propagation in the South China Sea,leading to sound transmission loss predictions that closely align with experimental observations.展开更多
To address the problem of underwater sound speed profile(SSP)inversion in underwater acoustic multipath channels,this paper combines deep learning and ray theory to propose an inversion method using a long short-term ...To address the problem of underwater sound speed profile(SSP)inversion in underwater acoustic multipath channels,this paper combines deep learning and ray theory to propose an inversion method using a long short-term memory(LSTM)network.Based on the equidistant characteristics of the horizontal line array,the proposed method takes the sensing matrix composed of multi-modal data,such as time difference of arrival and angle of arrival,as input,and utilizes the ability of the LSTM network to process timeseries data to mine the correlations between spatially ordered receiving array elements for sound speed profile inversion.On this basis,a time delay estimation method based on hard threshold estimation method and cross-correlation function is proposed to reduce the measurement errors of the sensing matrix and improve the anti-multipath performance.The feasibility and accuracy of the proposed method are verified through numerical simulations.Compared with the traditional optimization algorithm,the proposed algorithm better captures the nonlinear characteristics of SSP,with higher inversion accuracy and stronger noise resistance.展开更多
In order to improve the exploration effect of deep non-ferrous mineral resources, multi-channel observation methods for induced polarization （IP） electrical sounding data and their inversion imaging technology are s...In order to improve the exploration effect of deep non-ferrous mineral resources, multi-channel observation methods for induced polarization （IP） electrical sounding data and their inversion imaging technology are studied. First of all, four multi-channel observation methods are developed based on conventional IP electrical method, namely three-electrode and four-electrode arrays of unilateral and bilateral current transmitting. Then the maximum smoothness constrained inversion method of the least squares sense for IP electrical sounding data is proposed, and the inversion software is programmed. Finally, the simulation and inversion results of geo-electrical model for the proposed observation methods are analyzed. And the comparison results show that three-electrode array of bilateral current transmitting gives the best result, but the intensity in field work is larger than others; unilateral three-electrode and four-electrode arrays give the better results. Taking detection results and convenience of field exploration work into consideration, these two methods are more suitable for practical application; bilateral observation method of four-electrode array is not suitable for the detection of the steep ore bodies.展开更多
The upper air weather forecast data used in current business and research and digital data of the recently finished upper air meteorological monthly report were comparatively analyzed in complete data and quality cond...The upper air weather forecast data used in current business and research and digital data of the recently finished upper air meteorological monthly report were comparatively analyzed in complete data and quality condition of data, and sounding curve change caused by the difference of complete data was also compared, which evaluated advantages and disadvantages of two types of data.展开更多
To understand deep lithosphere structure beneath the Qinghai-Tibet Plateau more comprehensively and objectively and to explore important scientific issues,such as characteristics of plateau lithospheric deformation,st...To understand deep lithosphere structure beneath the Qinghai-Tibet Plateau more comprehensively and objectively and to explore important scientific issues,such as characteristics of plateau lithospheric deformation,state of strain,thermal structure,plate (or terrane) movement,and crust-mantle rheology,it is necessary to research the variation of crust-mantle electrical structure in the east-west direction in every geological unit.For this purpose,six super-broadband magnetotelluric (MT) sounding profiles have been completed by INDEPTH-MT Project in the Himalayas-Southern Tibet.Based on the imaging results from the six profiles,three-dimensional electrical conductivity structure of the crust and upper mantle has been analyzed for the research area.The result shows that the high-conductivity layers in the middle and lower crust exist widely in Southern Tibet,which extend discontinuously for more than 1000 km in the east-west direction and become thinner,shallower and more resistive toward the big turning of the Yarlung Zangbo River.The discussion on the rheology of lithosphere in Southern Tibet suggests that the mid-lower crust there is of high electrical conductivity,implying the existence of "partial-melt" and "hot fluid" in the thick crust of Tibet,which make the medium hot,soft,and plastic,or even able to flow.Combining the experimental result of petrophysics and the MT data,we estimate the melting percentage of the crustal material to be up to 5%-14%,which would reduce the viscosity of aplite in the crust to meet the flow condition;but for granite,it is likely not enough to cause such a change in rheology.展开更多
Songpan-Garze massif is located at the turning position of tectonics from the nearly west-east direction to the nearly north-south direction in the northeastern margin of Tibetan Plateau,with Zoigê basin in the c...Songpan-Garze massif is located at the turning position of tectonics from the nearly west-east direction to the nearly north-south direction in the northeastern margin of Tibetan Plateau,with Zoigê basin in the centre of the massif.In this paper,we build a crustal structure model of Zoigê basin and its surrounding folded orogenic belts using the deep seismic sounding data in this region.We also discuss structures and properties of the basement in Zoigê basin,tectonic relations between Zoigê upland basin and its surrounding folded orogenic belts,crustal deformation and thickening in the northeastern margin of Tibetan Plateau,and decoupling and relaxing processes in the crust.The results indicate that a special "Mesozoic basement" is formed of Triassic rocks with high density (2.65-2.75 g/cm3) and high velocity (5.6 km/s) in Zoigê basin.Songpan-Garze tectonic massif was transformed into two types of tectonic units with different crustal structures,i.e.,relatively stable Zoigê upland basin and active folded orogenic belts around the basin,in the course of the crustal material of Tibetan Plateau flowing eastward and obstructed by surrounding stable blocks.The thickening of the crust in the northeastern margin of Tibetan Plateau mainly occurred in the mid and lower crust,and the structure characterized by low velocities and multiple reflectors obviously appears in the folded orogenic belts around Zoigê basin.It implies that the mid and lower crust underwent a strong tectonic deformation in the folded orogenic areas.The thickness of the crust is about 50 km in Zoigê basin and the folded orogenic belts at the both southern and northern sides of Zoigê basin.The "Mountain root" cannot be identified.It is inferred that during the later orogenic period the eastwards flowing deep materials moved clockwise along the relatively relaxing southern side around the eastern tectonic knot under the obstructing of surrounding rigid massifs,and it resulted in the strong stretching action of the folded orogenic belts around Zoigê basin.展开更多
The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the ...The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s^(-1), exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s^(-1), exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.展开更多
A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measureme...A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measurements of E-field inside the thunderstorms were conducted in Pingliang, Gansu Provience, with the cooperation of an X-band weather radar. One E-field profile inside a thunderstorm was successfully acquired. The sounding data indicated four charge layers along the sounding trajectory, three in-side the thuderstorm and one at its lower boundary. The lower cloud boundary charge layer was negative, acting as a screening layer, and laid between 4.3 to 4.5 km a.s.l. The lower positive charge center (LPCC) existed between 4.5–5.3 km a.s.l. (from 3°C to -2°C); the main negative charge area was present between 5.4–6.6 km a.s.l. (-3°C to -10°C); the upper positive charge layer was between 6.7–7.2 km a.s.l. (-11°C to -14°C). The results support the tripole charge structure inside thunderstorms (above 0°C isotherm altitude), but the LPCC is much larger-than-usual in Chinese inland plateau.展开更多
A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvem...A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis （1D-Var） for the Unified Model （UM） data assimilation system at the Met Office, using the channel score index （CSI） as a figure of merit. Then, 200 channels were selected in order by counting each individual channel＇s CSI contribution. Compared with the operationally used 183 channels for the UM at the Met Office, the new set shares 149 channels, while the other 51 channels are new. Also examined is the selection from the entropy reduction method with the same 1D-Var approach, Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method. This is because the most important channels can be selected across the whole IASI observation spectrum. In the experimental trial runs using the UM global assimilation system, the new channels had an overall neutral impact in terms of improvement in forecasts, as compared with results from the operational channels. However, upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels. The reduction of moist biases was mainly due to the additional water vapor channels, which are sensitive to the upper-tropospheric water vapor.展开更多
In this paper, the admittance function between seafloor undulations and vertical gravity gradient anomalies was derived. Based on this admittance function, the bathymetry model of 1 minute resolution was predicted fro...In this paper, the admittance function between seafloor undulations and vertical gravity gradient anomalies was derived. Based on this admittance function, the bathymetry model of 1 minute resolution was predicted from vertical gravity gradient anomalies and ship soundings in the experimental area from the northwest Pacific. The accuracy of the model is evaluated using ship soundings and existing models, including ETOPO1, GEBCO, DTU10 and V15.1 from SIO. The model＇s STD is 69. 481m, comparable with V15.1 which is generally believed to have the highest accuracy.展开更多
基金funded by an NSFC Major Project (Grant No. 42090033)the China Meteorological Administration Youth Innovation Team “High-Value Climate Change Data Product Development and Application Services”(Grant No. CMA2023QN08)the National Meteorological Information Centre Surplus Funds Program (Grant NMICJY202310)。
文摘High-vertical-resolution radiosonde wind data are highly valuable for describing the dynamics of the meso-and microscale atmosphere. However, the current algorithm used in China's L-band radar sounding system for calculating highvertical-resolution wind vectors excessively smooths the data, resulting in significant underestimation of the calculated kinetic energy of gravity waves compared to similar products from other countries, which greatly limits the effective utilization of the data. To address this issue, this study proposes a novel method to calculate high-vertical-resolution wind vectors that utilizes the elevation angle, azimuth angle, and slant range from L-band radar. In order to obtain wind data with a stable quality, a two-step automatic quality control procedure, including the RMSE-F(root-mean-square error F) test and elemental consistency test are first applied to the slant range data, to eliminate continuous erroneous data caused by unstable signals or radar malfunctions. Then, a wind calculation scheme based on a sliding second-order polynomial fitting is utilized to derive the high-vertical-resolution radiosonde wind vectors. The evaluation results demonstrate that the wind data obtained through the proposed method show a high level of consistency with the high-resolution wind data observed using the Vaisala Global Positioning System and the data observed by the new Beidou Navigation Sounding System. The calculation of the kinetic energy of gravity waves in the recalculated wind data also reaches a level comparable to the Vaisala observations.
基金supported by Fundamental Research Funds for the Central Universities(No.2024YJS078)the National Natural Science Foundation of China(No.62341127,62221001 and 62171021)+1 种基金the Fundamental Research Funds for the Natural Science Foundation of Jiangsu Province,Major Project(No.BK2021200)the Key Research and Development Program of Zhejiang Province(No.2023C01003)。
文摘With the development of wireless communication,the fifth generation mobile communication technology(5G)has emerged as a hot topic in highspeed railway communication system and has moved towards industrial application.Investigating the radio propagation characteristics in 5G high-speed train(HST)scenarios is essential for enhancing wireless coverage and overall system performance.We propose a novel 5G passive sounding scheme to extract channel impulse responses(CIRs)using channel state information reference signals(CSI-RS)from the target 5G base station(BS).Detailed procedures for timefrequency synchronization,CSI-RS detection and extraction are presented through simulations.Through the laboratory work involving absolute power calibration,phase coherence calibration and power delay profile(PDP)validation,we validate the accuracy and performance of the developed platform.Furthermore,a measurement campaign was conducted in HST scenarios encompassing both residential and undeveloped areas.The path loss(PL)model and the channel characteristics including stationarity interval(SI),multipath components(MPCs),shadow fading(SF),Rician K-factor,root mean square(RMS)delay spread and received correlation coefficients are analyzed and fitted.The estimated channel characteristics and the statistical model presented in this paper will contribute to the research on HST radio propagation and the development of 5G railway communication systems.
文摘Introduction: Located in the central-western part of Côte d’Ivoire, the subsoil of the Gagnoa region is made up of sedimentary volcano formations and granitoids with developed fracturing. This complex Precambrian basement contains most of the region’s water resources. This is at the origin of the high failure rate during the various hydrogeological prospecting campaigns. Methodology: The database consists of resistivities from 42 holes and 51 trails drilled as part of the implementation of high-throughput drilling in the study area. The objective of this study is to deepen the knowledge of the fissured basement by interpreting profile curves and electrical soundings. It will be a question of classifying the different types of anomalies obtained on the profiles and their shapes. The orientation of the lineaments observed on the profiles was determined. Results: The interpretation of the geophysical data revealed various anomalies, the main ones being of the CC (Conductor Compartment) and CEDP (Contact between two bearings) types. These types of anomalies are mainly expressed in various forms: the “V”, “W” and “U” shapes. From these anomalies and the appearance of the electrical profiles, lineaments and their orientations were identified with N90-100, N130-140, N170-180 as major orientations. Conclusion: These results could contribute to a better understanding of the fractured environment of the Gagnoa region.
基金The Second Tibetan Plateau Scientific Expedition and Research Program under contract No.2019QZKK0102-02the National Natural Science Foundation of China under contract Nos 42230402,92158204,42176026,42076201,41049903,41149908,41249906,41249907,and 41249910+2 种基金the Guangdong Basic and Applied Basic Research Foundation under contract No.2022A1515240069the Marine Economic Development Special Program of Guangdong Province(Six Major Marine Industries):Research and Demonstration of Critical Technologies for Comprehensive Prevention and Control of Natural Disaster in Offshore Wind Farms,China under contract No.29[2023]the Fund of Fujian Provincial Key Laboratory of Marine Physical and Geological Processes under contract No.KLMPG-22-02.
文摘Shipboard radiosonde soundings are important for detecting and quantifying the multiscale variability of atmosphere-ocean interactions associated with mass exchanges.This study evaluated the accuracies of shipboard Global Positioning System(GPS)soundings in the eastern tropical Indian Ocean and South China Sea through a simultaneous balloon-borne inter-comparison of different radiosonde types.Our results indicate that the temperature and relative humidity(RH)measurements of GPS-TanKong(GPS-TK)radiosonde(used at most stations before 2012)have larger biases than those of ChangFeng-06-A(CF-06-A)radiosonde(widely used in current observation)when compared to reference data from Vaisala RS92-SGP radiosonde,with a warm bias of 5℃and dry bias of 10%during daytimes,and a cooling bias of-0.8℃and a moist bias of 6%during nighttime.These systematic biases are primarily attributed to the radiation effects and altitude deviation.An empirical correction algorithm was developed to retrieve the atmospheric temperature and RH profiles.The corrected profiles agree well with that of RS92-SGP,except for uncertainties of CF-06-A in the stratosphere.These correction algorithms were applied to the GPS-TK historical sounding records,reducing biases in the corrected temperature and RH profiles when compared to radio occultation data.The correction of GPS-TK historical records illustrated an improvement in capturing the marine atmospheric structure,with more accurate atmospheric boundary layer height,convective available potential energy,and convective inhibition in the tropical ocean.This study contributes significantly to improving the quality of GPS radiosonde soundings and promotes the sharing of observation in the eastern tropical Indian Ocean and South China Sea.
基金Supported by Open Research Fund Project of Key Laboratory of Meteorology and Ecological Environment of Hebei Province(Z202001Z,Z201602Z)Science and Technology Collaborative Innovation Fund Project in Bohai Rim Region(QYXM202004)Key Projects of Tianjin Meteorological Bureau(201801zdxm01)。
文摘Based on L-band sounding data,threshold method of relative humidity was used to analyze vertical distribution characteristics of precipitation cloud system in Tianjin region.The results showed that main precipitation cloud system affecting Tianjin is cold and warm mixed cloud,followed by cold cloud,and precipitation of warm cloud is less.During May-November,precipitation of cold and warm mixed cloud is dominant,and it is dominant by precipitation of cold cloud from January to April.In four seasons,the precipitation frequency of double-layer cloud is the most,and precipitation of single-layer cloud mainly appears during March-November,and peak is in June.Peak of cloud system with three or more layers all appears in July and August.The cold cloud and warm cloud catalysts should be selected respectively for artificial precipitation enhancement in Tianjin.In winter,cold cloud catalyst operation is selected;in spring,summer and autumn,the cold cloud catalyst is spread in the cold cloud area,and the warm cloud catalyst is distributed in the warm cloud area according to the conditions of cloud layer.
文摘[Objective] The research aimed to discuss shallowly the application of L-band sounding seconds data in the artificial precipitation. [Method] The characteristics, getting manner and displaying method of L-band sounding seconds data were introduced briefly. Moreover, its application prospect in the artificial precipitation operation was analyzed initially. We aimed to improve its application rate in the artificial precipitation operation. [Result] L-band sounding seconds data had the great improvement in the time-space resolution and the space positioning accuracy aspects when compared with the previous sounding data, and the precision reached the second level. It could provide the high-precision data basis for the assimilation of artificial precipitation numerical model initial field, and improve the numerical model. Moreover, the sounding product could provide the accurate scientific basis for the selection of artificial precipitation operation tool, the determination of operation height and range, and guide the artificial precipitation operation, and improve the operation efficiency. [Conclusion] The research provided the analysis and reference basis for the command of artificial precipitation operation.
基金under the support of the National Natural Science Foundation of China(Grant No.42388102),ChinaYouth Fund of the Natural Science Foundation of Hebei Province(Grant No.D2023523003),China。
文摘The continuously available satellites of European Galileo currently reach more than 25.To explore the rationality and reliability of the L-band and satellite laser ranging(SLR)data processing strategies,we design the Galileo L-band,the SLR-only,and the combined L-band/SLR dynamic precise orbit determination(POD)strategies by using the normal equations(NEQs)stacking,and investigate their continuity and stability by employing the Galileo L-band data and SLR observations for the time span of the whole year of 2023,based on the Bei Dou/GNSS analysis center platform of Shandong University by using the modified Bernese GNSS Software Version 5.4.The orbital consistency of the L-band 1-day solution is the best with the Three-dimensional Root-Mean-Square(3D-RMS)values of 3.6 cm compared with the Center for Orbit Determination in Europe Multi-GNSS Experiment(COM)orbits,the corresponding values is 1.4 cm,2.5 cm,and 2.3 cm in Radial,the Tangential,and the Normal(RTN)direction,respectively.While the SLR-only 9-day arc length is optimal with the RTN values of 5.3 cm,30 cm,and 38.2 cm,as well as the 3D-RMS values of 48.9 cm.Encouragingly,the difference of the orbital accuracy between the combined L-band/SLR multi-day solution and the COM orbits is reduced by 0.5 cm and 0.9 cm,0.6 cm and 1.2 cm in T-,and N-direction for the 3-and 5-day solution respectively.The corresponding values improve 0.7 cm and 0.9 cm,1.4 cm and 1.8 cm for the 3-and 5-day orbital overlaps difference between the combined L-band/SLR and the L-band solution.Take the E09 satellite as a case study,the SLR-only orbital accuracy is regularly optimized as the multi-day arc lengthens and with the sites increase.Furthermore,the SLR residuals of its three types of orbits further demonstrate the positive contribution of SLR to the combination of the GNSS and SLR techniques.
基金National Natural Science Foundation of China(No.51705545)。
文摘The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.
文摘Large portions of the tunnel boring machine(TBM)construction cost are attributed to disc cutter consumption,and assessing the disc cutter's wear level can help determine the optimal time to replace the disc cutter.Therefore,the need to monitor disc cutter wear in real-time has emerged as a technical challenge for TBMs.In this study,real-time disc cutter wear monitoring is developed based on sound and vibration sensors.For this purpose,the microphone and accelerometer were used to record the sound and vibration signals of cutting three different types of rocks with varying abrasions on a laboratory scale.The relationship between disc cutter wear and the sound and vibration signal was determined by comparing the measurements of disc cutter wear with the signal plots for each sample.The features extracted from the signals showed that the sound and vibration signals are impacted by the progression of disc wear during the rock-cutting process.The signal features obtained from the rock-cutting operation were utilized to verify the machine learning techniques.The results showed that the multilayer perceptron(MLP),random subspace-based decision tree(RS-DT),DT,and random forest(RF)methods could predict the wear level of the disc cutter with an accuracy of 0.89,0.951,0.951,and 0.927,respectively.Based on the accuracy of the models and the confusion matrix,it was found that the RS-DT model has the best estimate for predicting the level of disc wear.This research has developed a method that can potentially determine when to replace a tool and assess disc wear in real-time.
基金supported by the National Key Research and Development Program of China(2023YFF1203502)the National Natural Science Foundation of China(62171300,62301343,and 62394314)+1 种基金the Project of Cultivation for Young Top-Notch Talents of Beijing Municipal Institutions(BPHR202203109)the Capital Medical University Research and Development Fund(PYZ22027).
文摘The ability to localize sound sources rapidly allows human beings to efficiently understand the surrounding environment.Previous studies have suggested that there is an auditory“where”pathway in the cortex for processing sound locations.The neural activation in regions along this pathway encodes sound locations by opponent hemifield coding,in which each unilateral region is activated by sounds coming from the contralateral hemifield.However,it is still unclear how these regions interact with each other to form a unified representation of the auditory space.In the present study,we investigated whether functional connectivity in the auditory“where”pathway encoded sound locations during passive listening.Participants underwent functional magnetic resonance imaging while passively listening to sounds from five distinct horizontal locations(−90°,−45°,0°,45°,90°).We were able to decode sound locations from the functional connectivity patterns of the“where”pathway.Furthermore,we found that such neural representation of sound locations was primarily based on the coding of sound lateralization angles to the frontal midline.In addition,whole-brain analysis indicated that functional connectivity between occipital regions and the primary auditory cortex also encoded sound locations by lateralization angles.Overall,our results reveal a lateralization-angle-based representation of sound locations encoded by functional connectivity patterns,which could add on the activation-based opponent hemifield coding to provide a more precise representation of the auditory space.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174048 and 12204128)。
文摘A Wentzel-Kramers-Brillouin(WKB)method is introduced for obtaining a uniform asymptotic solution for underwater sound propagation at very low frequencies in deep ocean.The method utilizes a mode sum and employs the reference functions method to describe the solution to the depth-separated wave equation approximately using parabolic cylinder functions.The conditions for the validity of this approximation are also discussed.Furthermore,a formula that incorporates waveguide effects for the modal group velocity is derived,revealing that boundary effects at very low frequencies can have a significant impact on the propagation characteristics of even low-order normal modes.The present method not only offers improved accuracy compared to the classical WKB approximation and the uniform asymptotic approximation based on Airy functions,but also provides a wider range of depth applicability.Additionally,this method exhibits strong agreement with numerical methods and offers valuable physical insights.Finally,the method is applied to the study of very-low-frequency sound propagation in the South China Sea,leading to sound transmission loss predictions that closely align with experimental observations.
基金supported by the National Natural Science Foundation of China(62371404,62271425,62071401).
文摘To address the problem of underwater sound speed profile(SSP)inversion in underwater acoustic multipath channels,this paper combines deep learning and ray theory to propose an inversion method using a long short-term memory(LSTM)network.Based on the equidistant characteristics of the horizontal line array,the proposed method takes the sensing matrix composed of multi-modal data,such as time difference of arrival and angle of arrival,as input,and utilizes the ability of the LSTM network to process timeseries data to mine the correlations between spatially ordered receiving array elements for sound speed profile inversion.On this basis,a time delay estimation method based on hard threshold estimation method and cross-correlation function is proposed to reduce the measurement errors of the sensing matrix and improve the anti-multipath performance.The feasibility and accuracy of the proposed method are verified through numerical simulations.Compared with the traditional optimization algorithm,the proposed algorithm better captures the nonlinear characteristics of SSP,with higher inversion accuracy and stronger noise resistance.
基金Project(41174102)supported by the National Natural Science Foundation of China
文摘In order to improve the exploration effect of deep non-ferrous mineral resources, multi-channel observation methods for induced polarization （IP） electrical sounding data and their inversion imaging technology are studied. First of all, four multi-channel observation methods are developed based on conventional IP electrical method, namely three-electrode and four-electrode arrays of unilateral and bilateral current transmitting. Then the maximum smoothness constrained inversion method of the least squares sense for IP electrical sounding data is proposed, and the inversion software is programmed. Finally, the simulation and inversion results of geo-electrical model for the proposed observation methods are analyzed. And the comparison results show that three-electrode array of bilateral current transmitting gives the best result, but the intensity in field work is larger than others; unilateral three-electrode and four-electrode arrays give the better results. Taking detection results and convenience of field exploration work into consideration, these two methods are more suitable for practical application; bilateral observation method of four-electrode array is not suitable for the detection of the steep ore bodies.
基金Supported by National Natural Science Foundation(40705025)~~
文摘The upper air weather forecast data used in current business and research and digital data of the recently finished upper air meteorological monthly report were comparatively analyzed in complete data and quality condition of data, and sounding curve change caused by the difference of complete data was also compared, which evaluated advantages and disadvantages of two types of data.
基金supported by National Natural Science Foundation of China (Grant No. 40674045)National Special Project of China Sino-Probe-01
文摘To understand deep lithosphere structure beneath the Qinghai-Tibet Plateau more comprehensively and objectively and to explore important scientific issues,such as characteristics of plateau lithospheric deformation,state of strain,thermal structure,plate (or terrane) movement,and crust-mantle rheology,it is necessary to research the variation of crust-mantle electrical structure in the east-west direction in every geological unit.For this purpose,six super-broadband magnetotelluric (MT) sounding profiles have been completed by INDEPTH-MT Project in the Himalayas-Southern Tibet.Based on the imaging results from the six profiles,three-dimensional electrical conductivity structure of the crust and upper mantle has been analyzed for the research area.The result shows that the high-conductivity layers in the middle and lower crust exist widely in Southern Tibet,which extend discontinuously for more than 1000 km in the east-west direction and become thinner,shallower and more resistive toward the big turning of the Yarlung Zangbo River.The discussion on the rheology of lithosphere in Southern Tibet suggests that the mid-lower crust there is of high electrical conductivity,implying the existence of "partial-melt" and "hot fluid" in the thick crust of Tibet,which make the medium hot,soft,and plastic,or even able to flow.Combining the experimental result of petrophysics and the MT data,we estimate the melting percentage of the crustal material to be up to 5%-14%,which would reduce the viscosity of aplite in the crust to meet the flow condition;but for granite,it is likely not enough to cause such a change in rheology.
基金supportted by the National Natural Science Fundation of China (Grant No.40334040)
文摘Songpan-Garze massif is located at the turning position of tectonics from the nearly west-east direction to the nearly north-south direction in the northeastern margin of Tibetan Plateau,with Zoigê basin in the centre of the massif.In this paper,we build a crustal structure model of Zoigê basin and its surrounding folded orogenic belts using the deep seismic sounding data in this region.We also discuss structures and properties of the basement in Zoigê basin,tectonic relations between Zoigê upland basin and its surrounding folded orogenic belts,crustal deformation and thickening in the northeastern margin of Tibetan Plateau,and decoupling and relaxing processes in the crust.The results indicate that a special "Mesozoic basement" is formed of Triassic rocks with high density (2.65-2.75 g/cm3) and high velocity (5.6 km/s) in Zoigê basin.Songpan-Garze tectonic massif was transformed into two types of tectonic units with different crustal structures,i.e.,relatively stable Zoigê upland basin and active folded orogenic belts around the basin,in the course of the crustal material of Tibetan Plateau flowing eastward and obstructed by surrounding stable blocks.The thickening of the crust in the northeastern margin of Tibetan Plateau mainly occurred in the mid and lower crust,and the structure characterized by low velocities and multiple reflectors obviously appears in the folded orogenic belts around Zoigê basin.It implies that the mid and lower crust underwent a strong tectonic deformation in the folded orogenic areas.The thickness of the crust is about 50 km in Zoigê basin and the folded orogenic belts at the both southern and northern sides of Zoigê basin.The "Mountain root" cannot be identified.It is inferred that during the later orogenic period the eastwards flowing deep materials moved clockwise along the relatively relaxing southern side around the eastern tectonic knot under the obstructing of surrounding rigid massifs,and it resulted in the strong stretching action of the folded orogenic belts around Zoigê basin.
基金Funding for the fieldwork has primarily come from China Earthquake Administration and the People’s Government of Guangdong Provincesupport by the National Natural Science Foundation of China (No. 41676057)
文摘The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s^(-1), exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s^(-1), exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.
基金supported by the National Natural Science Foundation of China (Grant No. 40675008) Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KZCX2-YW-206)Hundred Tal-ents Program of CAS
文摘A strong electric (E) field sounding system was designed to measure the vertical component of the E-fields, temperature, relative humidity and GPS data along the sounding path. In the summer of 2008, in situ measurements of E-field inside the thunderstorms were conducted in Pingliang, Gansu Provience, with the cooperation of an X-band weather radar. One E-field profile inside a thunderstorm was successfully acquired. The sounding data indicated four charge layers along the sounding trajectory, three in-side the thuderstorm and one at its lower boundary. The lower cloud boundary charge layer was negative, acting as a screening layer, and laid between 4.3 to 4.5 km a.s.l. The lower positive charge center (LPCC) existed between 4.5–5.3 km a.s.l. (from 3°C to -2°C); the main negative charge area was present between 5.4–6.6 km a.s.l. (-3°C to -10°C); the upper positive charge layer was between 6.7–7.2 km a.s.l. (-11°C to -14°C). The results support the tripole charge structure inside thunderstorms (above 0°C isotherm altitude), but the LPCC is much larger-than-usual in Chinese inland plateau.
基金supported by the KMA Research and Development Program under Grant No.KMIPA 20151060supported by the BK21 Plus Project of the Korean government
文摘A new set of Infrared Atmospheric Sounding Interferometer （IASI） channels was re-selected from 314 EUMETSAT channels. In selecting channels, we calculated the impact of the individually added channel on the improvement in the analysis outputs from a one-dimensional variational analysis （1D-Var） for the Unified Model （UM） data assimilation system at the Met Office, using the channel score index （CSI） as a figure of merit. Then, 200 channels were selected in order by counting each individual channel＇s CSI contribution. Compared with the operationally used 183 channels for the UM at the Met Office, the new set shares 149 channels, while the other 51 channels are new. Also examined is the selection from the entropy reduction method with the same 1D-Var approach, Results suggest that channel selection can be made in a more objective fashion using the proposed CSI method. This is because the most important channels can be selected across the whole IASI observation spectrum. In the experimental trial runs using the UM global assimilation system, the new channels had an overall neutral impact in terms of improvement in forecasts, as compared with results from the operational channels. However, upper-tropospheric moist biases shown in the control run with operational channels were significantly reduced in the experimental trial with the newly selected channels. The reduction of moist biases was mainly due to the additional water vapor channels, which are sensitive to the upper-tropospheric water vapor.
基金supported by the Director Foundation of Institute of Seismology,China Earthquake Administration(IS201326125)the National Natural Science Foundation of China(41204019,41304003)
文摘In this paper, the admittance function between seafloor undulations and vertical gravity gradient anomalies was derived. Based on this admittance function, the bathymetry model of 1 minute resolution was predicted from vertical gravity gradient anomalies and ship soundings in the experimental area from the northwest Pacific. The accuracy of the model is evaluated using ship soundings and existing models, including ETOPO1, GEBCO, DTU10 and V15.1 from SIO. The model＇s STD is 69. 481m, comparable with V15.1 which is generally believed to have the highest accuracy.
