When using ambient noise data to invert velocity and anisotropic structures,the two-station inter-correlation method requires synchronous stations.If there are multiple temporary seismic arrays with different observat...When using ambient noise data to invert velocity and anisotropic structures,the two-station inter-correlation method requires synchronous stations.If there are multiple temporary seismic arrays with different observation periods in the study area,the seismic arrays are usually used selectively.This paper takes the Sanjiang lateral collision zone as an example,and utilizes the ambient noise data of multiple temporary seismic arrays at different observation periods to improve the accuracy of regional velocity structure and anisotropy by anchoring permanent seismic stations.In this paper,notable enhancements in S-wave velocity and azimuthal anisotropy imaging accuracy are achieved by integrating data from three temporary seismic arrays(SJ-Array,SL-Array,and Chin Array-I)with the permanent seismic network.The imaging resolutions for the S-wave velocity and azimuthal anisotropy above 40 km are 0.4°×0.4°and 0.5°×0.5°,respectively.In the region of the most concentrated array coverage,the imaging resolution of S-wave velocity can reach 0.33°×0.33°at depths of less than 30 km.These findings underscore the significant improvement in deep structure imaging accuracy by the synergistic integration of ambient noise data from multiple temporary seismic arrays.展开更多
An imaging accuracy improving method is established, within which a distance coefficient including location information between sparse array configuration and the location of defect is proposed to select higher signal...An imaging accuracy improving method is established, within which a distance coefficient including location information between sparse array configuration and the location of defect is proposed to select higher signal- to-noise ratio data from all experimental data and then to use these selected data for elliptical imaging. Tile relationships among imaging accuracy, distance coefficient and residual direct wave are investigated, and then the residual direct wave is introduced to make the engineering application more convenient. The effectiveness of the proposed method is evaluated experimentally by sparse transducer array of a rectangle, and the results reveal that selecting experimental data of smaller distance coefficient can effectively improve imaging accuracy. Moreover, the direct wave difference increases with the decrease of the distance coefficient, which implies that the imaging accuracy can be effectively improved by using the experimental data of the larger direct wave difference.展开更多
In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet a...In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3 D scene, and the sum modulus(SMD) blur metric is taken on these slice images to achieve the depth information of the 3 D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.展开更多
In the prosthetic socket design, aimed at the high cost and radiation deficiency caused by CT scanning which is a routine technique to obtain the cross-sectional image of the residual limb, a new ultrasonic scanning m...In the prosthetic socket design, aimed at the high cost and radiation deficiency caused by CT scanning which is a routine technique to obtain the cross-sectional image of the residual limb, a new ultrasonic scanning method is developed to acquire the bones and skin contours of the residual limb. Using a pig fore-leg as the scanning object, an overlapping algorithm is designed to reconstruct the 2D cross-sectional image, the contours of the bone and skin are extracted using edge detection algorithm and the 3D model of the pig fore-leg is reconstructed by using reverse engineering technology. The results of checking the accuracy of the image by scanning a cylinder work pieces show that the extracted contours of the cylinder are quite close to the standard circumference. So it is feasible to get the contours of bones and skin by ultrasonic scanning. The ultrasonic scanning system featuring no radiation and low cost is a kind of new means of cross section scanning for medical images.展开更多
One-sided ascending or descending Synthetic Aperture Radar（SAR） stereoradargrammetry has limited accuracy of topographic mapping due to the short spatial baseline（-100 km） and small intersection angle. In order to...One-sided ascending or descending Synthetic Aperture Radar（SAR） stereoradargrammetry has limited accuracy of topographic mapping due to the short spatial baseline（-100 km） and small intersection angle. In order to improve the performance and reliability of generating digital elevation model（DEM） from spaceborne SAR radargrammetry, an exploration of two-sided stereoradargrammetry from the combination of ascending and descending orbits with geometric configuration of long spatial baseline（-1000 km） was conducted in this study. The slant-range geometry between SAR sensors to the earth surface and the Doppler positioning equations were employed to establish the stereoscopic intersection model. The measurement uncertainty of two-sided radargrammetric elevation was estimated on the basis of radar parallax of homogeneous points between input SAR images. Two stereo-pairs of ALOS/PALSAR（Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar） acquisitions with the orbital separation almost 1080 km over the west Sichuan foreland basin with rolling topography in southwestern China were employed in the study to obtain the up-to-date terrain data after the 2008 Wenchuan earthquake that hit this area. Thequantitative accuracy assessment of two-sided radargrammetric DEM was performed with reference to field GPS observations. The experimental results show that the elevation accuracy reaches 5.5 m without ground control points（GCPs） used, and the accuracy is further improved to 1.5 m with only one GPS GCP used as the least constraint. The theoretical analysis and testing results demonstrate that the twosided long baseline SAR radargrammetry from the ascending and descending orbits can be a very promising technical alternative for large-area and high accuracy topographic mapping.展开更多
Single-molecule localization microscopy(SMLM)provides nanoscale imaging,but pixel integration of acquired SMLM images limited the choice of sampling rate,which restricts the information content conveyed within each im...Single-molecule localization microscopy(SMLM)provides nanoscale imaging,but pixel integration of acquired SMLM images limited the choice of sampling rate,which restricts the information content conveyed within each image.We propose an upsampled point spread function(PSF)inverse modeling method for large-pixel singlemolecule localization,enabling precise three-dimensional superresolution imaging with a sparse sampling rate.展开更多
We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imagin...We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imaging window material to further compensate for time-dependent system fluctuations and position-dependent variation in the window thickness. Our proposed method not only improves the accuracy, but also simplifies the imaging procedure and reduces measurement times.展开更多
We present a range-gating delayed detection super-resolution imaging Iidar with high accuracy based on the signal intensities of three consecutive delay samples. The system combines the range and signal intensity info...We present a range-gating delayed detection super-resolution imaging Iidar with high accuracy based on the signal intensities of three consecutive delay samples. The system combines the range and signal intensity information from multi-pulse detections to calculate the pulse peak position under the assumption of a Gaussian pulse shape. Experimental results indicate that the proposed algorithm effectively calculates pulse peak position and exhibits excellent accuracy with super-resolution. Accuracy analysis shows that accuracy is best improved by enhancing signal-to-noise ratio, strategically selecting samples, reducing pulse width, and appropriately choosing the delayed periods between samples.展开更多
Streak tube imaging lidar （STIL） is an active imaging system that has a high range accuracy with tile use of a pulsed lapser transmitter and streak tube receiver to produce 3D range inlages. This work investigates t...Streak tube imaging lidar （STIL） is an active imaging system that has a high range accuracy with tile use of a pulsed lapser transmitter and streak tube receiver to produce 3D range inlages. This work investigates the effect of tile time bin size oil the range accuracy of STIL systems based on the peak detection algorithm. The nunlerical simulation indicates that the time bin size has a significant effect on the range aceuracy, resulting in a modified analytical estimate of the range error. An indoor experilnent with a planar target is carried out to validate the theory that shows the linear relationship between tile range error and the time bin size. Finer 3D depth iinages of a fist model are acquired by using a smaller time bin size and the best range error of 0.003 In is achieved with the optimal time bin size of 0.07 ns.展开更多
基金supported by Key Projects of National Natural Science Foundation of China(Project 42330311)Central Publicinterest Scientific Institution Basal Research Fund(No.2021IEF0103)National Key R&D Project of China(2017YFC1500304)。
文摘When using ambient noise data to invert velocity and anisotropic structures,the two-station inter-correlation method requires synchronous stations.If there are multiple temporary seismic arrays with different observation periods in the study area,the seismic arrays are usually used selectively.This paper takes the Sanjiang lateral collision zone as an example,and utilizes the ambient noise data of multiple temporary seismic arrays at different observation periods to improve the accuracy of regional velocity structure and anisotropy by anchoring permanent seismic stations.In this paper,notable enhancements in S-wave velocity and azimuthal anisotropy imaging accuracy are achieved by integrating data from three temporary seismic arrays(SJ-Array,SL-Array,and Chin Array-I)with the permanent seismic network.The imaging resolutions for the S-wave velocity and azimuthal anisotropy above 40 km are 0.4°×0.4°and 0.5°×0.5°,respectively.In the region of the most concentrated array coverage,the imaging resolution of S-wave velocity can reach 0.33°×0.33°at depths of less than 30 km.These findings underscore the significant improvement in deep structure imaging accuracy by the synergistic integration of ambient noise data from multiple temporary seismic arrays.
文摘An imaging accuracy improving method is established, within which a distance coefficient including location information between sparse array configuration and the location of defect is proposed to select higher signal- to-noise ratio data from all experimental data and then to use these selected data for elliptical imaging. Tile relationships among imaging accuracy, distance coefficient and residual direct wave are investigated, and then the residual direct wave is introduced to make the engineering application more convenient. The effectiveness of the proposed method is evaluated experimentally by sparse transducer array of a rectangle, and the results reveal that selecting experimental data of smaller distance coefficient can effectively improve imaging accuracy. Moreover, the direct wave difference increases with the decrease of the distance coefficient, which implies that the imaging accuracy can be effectively improved by using the experimental data of the larger direct wave difference.
基金supported by the National Natural Science Foundation of China(Nos.11474169 and 61675100)the Tianjin Natural Science Foundation(No.15JCYBJC16900)
文摘In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3 D scene, and the sum modulus(SMD) blur metric is taken on these slice images to achieve the depth information of the 3 D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.
基金This project is supported by National Hi-tech Research and Development Program of China(863 Program, No.2002AA421130)Excellent Doctoral Dissertation Fund(No.200026).
文摘In the prosthetic socket design, aimed at the high cost and radiation deficiency caused by CT scanning which is a routine technique to obtain the cross-sectional image of the residual limb, a new ultrasonic scanning method is developed to acquire the bones and skin contours of the residual limb. Using a pig fore-leg as the scanning object, an overlapping algorithm is designed to reconstruct the 2D cross-sectional image, the contours of the bone and skin are extracted using edge detection algorithm and the 3D model of the pig fore-leg is reconstructed by using reverse engineering technology. The results of checking the accuracy of the image by scanning a cylinder work pieces show that the extracted contours of the cylinder are quite close to the standard circumference. So it is feasible to get the contours of bones and skin by ultrasonic scanning. The ultrasonic scanning system featuring no radiation and low cost is a kind of new means of cross section scanning for medical images.
基金supported by the National Natural Science Foundation of China(Grant Nos.41472255,51178404)Open Research Fund by Sichuan Engineering Research Center for Emergency Mapping & Disaster Reduction(Program K2014B006)Fundamental Research Funds for the Central Universities(Grant Nos.SWJTU12ZT07,2682014BR014)
文摘One-sided ascending or descending Synthetic Aperture Radar（SAR） stereoradargrammetry has limited accuracy of topographic mapping due to the short spatial baseline（-100 km） and small intersection angle. In order to improve the performance and reliability of generating digital elevation model（DEM） from spaceborne SAR radargrammetry, an exploration of two-sided stereoradargrammetry from the combination of ascending and descending orbits with geometric configuration of long spatial baseline（-1000 km） was conducted in this study. The slant-range geometry between SAR sensors to the earth surface and the Doppler positioning equations were employed to establish the stereoscopic intersection model. The measurement uncertainty of two-sided radargrammetric elevation was estimated on the basis of radar parallax of homogeneous points between input SAR images. Two stereo-pairs of ALOS/PALSAR（Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar） acquisitions with the orbital separation almost 1080 km over the west Sichuan foreland basin with rolling topography in southwestern China were employed in the study to obtain the up-to-date terrain data after the 2008 Wenchuan earthquake that hit this area. Thequantitative accuracy assessment of two-sided radargrammetric DEM was performed with reference to field GPS observations. The experimental results show that the elevation accuracy reaches 5.5 m without ground control points（GCPs） used, and the accuracy is further improved to 1.5 m with only one GPS GCP used as the least constraint. The theoretical analysis and testing results demonstrate that the twosided long baseline SAR radargrammetry from the ascending and descending orbits can be a very promising technical alternative for large-area and high accuracy topographic mapping.
基金National Key Research and Development Program of China(2024YFF0726003)Shenzhen Medical Research Fund(B2302038)+8 种基金National Natural Science Foundationof China(62375116)Key,Technology Research and Development Program of Shandong Province(2021CXGC010212)Shenzhen Science and Technology Innovation Program JCYJ20220818100416036,KQTD20200820113012029)BasicandApplied Basic Research Foundation of Guangdong Province(2024A1515011565)Postdoctoral Fellowship Program of CPSF(GZC20240651)GuangdongProvincial Key Laboratory of Advanced Biomaterials(2022B1212010003)Startup Grant from Southern University of Science and TechnologyCenter for Computational Science and Engineering of Southern University of Science and Technology。
文摘Single-molecule localization microscopy(SMLM)provides nanoscale imaging,but pixel integration of acquired SMLM images limited the choice of sampling rate,which restricts the information content conveyed within each image.We propose an upsampled point spread function(PSF)inverse modeling method for large-pixel singlemolecule localization,enabling precise three-dimensional superresolution imaging with a sparse sampling rate.
基金Research Grants Council of Hong Kong(415313,14205514)Direct Grant,Chinese University of Hong Kong
文摘We introduce a novel method to accurately extract the optical parameters in terahertz reflection imaging. Our method builds on standard self-referencing methods using the reflected signal from the bottom of the imaging window material to further compensate for time-dependent system fluctuations and position-dependent variation in the window thickness. Our proposed method not only improves the accuracy, but also simplifies the imaging procedure and reduces measurement times.
文摘We present a range-gating delayed detection super-resolution imaging Iidar with high accuracy based on the signal intensities of three consecutive delay samples. The system combines the range and signal intensity information from multi-pulse detections to calculate the pulse peak position under the assumption of a Gaussian pulse shape. Experimental results indicate that the proposed algorithm effectively calculates pulse peak position and exhibits excellent accuracy with super-resolution. Accuracy analysis shows that accuracy is best improved by enhancing signal-to-noise ratio, strategically selecting samples, reducing pulse width, and appropriately choosing the delayed periods between samples.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of China under Grant No.2012YQ040164
文摘Streak tube imaging lidar （STIL） is an active imaging system that has a high range accuracy with tile use of a pulsed lapser transmitter and streak tube receiver to produce 3D range inlages. This work investigates the effect of tile time bin size oil the range accuracy of STIL systems based on the peak detection algorithm. The nunlerical simulation indicates that the time bin size has a significant effect on the range aceuracy, resulting in a modified analytical estimate of the range error. An indoor experilnent with a planar target is carried out to validate the theory that shows the linear relationship between tile range error and the time bin size. Finer 3D depth iinages of a fist model are acquired by using a smaller time bin size and the best range error of 0.003 In is achieved with the optimal time bin size of 0.07 ns.
