检索结果-南通市图书馆

A Photon-Counting full-waveform Lidar

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2019年第9期36卷 23-27页

作者： Bing-Cheng Du Zhao-Hui Li Guang-Yue Shen Tian-Xiang Zheng Hai-Yan Zhang Lei Yang Guang Wu State Key Laboratory of Precision Spectroscop y East China Normal UniversityShanghai 200062 Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006

We present the results of using a photon-eounting full-waveform lidar to obtain detailed target information with high *** parameters of the waveforms(i.e.,vertical structure,peak position,peak amplitude,peak width and backscatter cross section)are derived with a high resolution limit of 31 mm to establish the vertical structure and scattering properties of targets,which contribute to the recognition and classification of various *** photon-counting full-waveform lidar has higher resolution than linear-mode full-waveform lidar,and it can obtain more specific target information compared to photon-counting discrete-point lidar,which can provide a potential alternative technique for tomographic surveying and mapping.

关键词： SPD A Photon-Counting full-waveform Lidar

Denoising for satellite laser altimetry full-waveform data based on EMD-Hurst analysis

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2020年第11期13卷 1212-1229页

作者： Zhijie Zhang Huan Xie Xiaohua Tong Hanwei Zhang Yang Liu Binbin Li School of Surveying and Land Information Engineering Henan Polytechnic UniversityJiaozuoPeople’s Republic of China College of Surveying and Geo-Informatics and State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghaiPeople’s Republic of China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghaiPeople’s Republic of China College of Marine Science Shanghai Ocean UniversityShanghaiPeople’s Republic of China

full-waveform decomposition is crucial for obtaining accurate satelliteground distance,the accuracy of which is severely affected by ***,the traditional filters all depend on filtering *** paper presents a new and adaptive method for denoising based on empirical mode decomposition(EMD)and Hurst analysis(EMD-Hurst).The noisy full-waveforms are first decomposed into their intrinsic mode functions(IMFs),and the Hurst exponent of each IMF is established by the detrended fluctuation *** IMF is regarded as the highfrequency noise and is deleted if its Hurst exponent is≤*** simulated and real full-waveforms were conducted to validate and evaluate the method by comparing with six other IMF selection methods via metrics like waveform decomposition consistency ratio(CR),average error of decomposition parameters,and ICESat/GLAS waveformparameter product *** comparisons show that:(1)under different SNR conditions,EMD-Hurst performs robustly and obtains a higher CR than other EMD based methods;(2)obtains the highest average CR and a relatively lower average error for the echo parameters;and(3)peak numbers and fitting accuracy for GLAH01 are more reasonable and precise than those of GLAH05,which could offer a good reference for the processing on future space-borne full-waveform data.

关键词： EMD-Hurst satellite laser altimetry full-waveform denoising IMF selection

Influence of voxel size on forest canopy height estimates using full-waveform airborne LiDAR data

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forest Ecosystems 2020年第3期7卷 392-403页

作者： Cheng Wang Shezhou Luo Xiaohuan Xi Sheng Nie Dan Ma Youju Huang College of Resources and Environment Fujian Agriculture and Forestry UniversityFuzhou350002China Key Laboratory of Digital Earth Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijing100094China Guangxi Zhuang Autonomous Region Institute of Natural Resources Remote Sensing Nanning530023China

Background: Forest canopy height is a key forest structure parameter. Precisely estimating forest canopy height is vital to improve forest management and ecological modelling. Compared with discrete-return LiDAR(Light Detection and Ranging), small-footprint full-waveform airborne LiDAR(FWL) techniques have the capability to acquire precise forest structural information. This research mainly focused on the influence of voxel size on forest canopy height ***: A range of voxel sizes(from 10.0 m to 40.0 m interval of 2 m) were tested to obtain estimation accuracies of forest canopy height with different voxel sizes. In this study, all the waveforms within a voxel size were aggregated into a voxel-based LiDAR waveform, and a range of waveform metrics were calculated using the voxelbased LiDAR waveforms. Then, we established estimation model of forest canopy height using the voxel-based waveform metrics through Random Forest(RF) regression *** and conclusions: The results showed the voxel-based method could reliably estimate forest canopy height using FWL data. In addition, the voxel sizes had an important influence on the estimation accuracies(R2 ranged from 0.625 to 0.832) of forest canopy height. However, the R2 values did not monotonically increase or decrease with the increase of voxel size in this study. The best estimation accuracy produced when the voxel size was 18 m(R2= 0.832, RMSE = 2.57 m, RMSE% = 20.6%). Compared with the lowest estimation accuracy, the R2 value had a significant improvement(33.1%) when using the optimal voxel size. Finally, through the optimal voxel size, we produced the forest canopy height distribution map for this study area using RF regression model. Our findings demonstrate that the optimal voxel size need to be determined for improving estimation accuracy of forest parameter using small-footprint FWL data.

关键词： Voxel size Airborne LiDAR full-waveform Forests Canopy height

Q full-waveform inversion based on the viscoacoustic equation

在线全文

学校读者我要写书评

暂无评论

Applied Geophysics 2019年第1期16卷 77-91页

作者： Wang En-Jiang Liu Yang Ji Yu-Xin Chen Tian-Sheng Liu Tao State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing100083 School of Earth Science and Engineering Hohai UniversityNanjing210098 College of Geophysics and Information Engineering China University of Petroleum (Beijing)Beijing102249 Sinopec Petroleum Exploration and Production Research Institute Beijing100083 Sinopec Key Laboratory of Multiwave Seismic Technology Beijing100083

Presently, most full-waveform inversion methods are developed for elastic media and ignore the effect of attenuation. The calculation of the quality factor Q is based on velocity parameter inversion under the assumption of a given Q-model that is obtained by tomographic inversion. However, the resolution of the latter is low and cannot reflect the amplitude attenuation and phase distortion during wave propagation in viscoelastic media. Thus, a Q waveform inversion method is proposed. First, we use standard linear body theory to describe attenuation and then we derive the simplified viscoacoustic equation that characterizes amplitude attenuation and phase distortion. In comparison with conventional equations, the simplifi ed equation involves no memory variables and therefore requires less memory during computation. Moreover, the implementations of the attenuation compensation are easier. The adjoint equation and the corresponding gradient equation with respect to either L2-norm or the zero-lag cross-correlation objective function are then derived and the regularization strategy for overcoming the instability during numerical solution of the adjoint equation is proposed. The Q waveform inversion is developed using the limited-memory Broyden–Fletcher– Goldfarb–Shanno (L-BFGS) iteration method for known velocity. To alleviate the dependence of the waveform inversion on the initial model and overcome cycle skipping to some extent, we adopt multiscale analysis. Furthermore, anti-noise property and double-parameter inversion are assessed based on the results of numerical modeling.

关键词： Quality factor Q full-waveform inversion attenuation stability

full-waveform Velocity Inversion Based on the Acoustic Wave Equation

在线全文

学校读者我要写书评

暂无评论

American Journal of Computational Mathematics 2013年第3期3卷 13-20页

作者： Wensheng Zhang Jia Luo Institute of Computational Mathematics and Scientific/Engineering Computing LSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing P. R. China

full-waveform velocity inversion based on the acoustic wave equation in the time domain is investigated in this paper. The inversion is the iterative minimization of the misfit between observed data and synthetic data obtained by a numerical solution of the wave equation. Two inversion algorithms in combination with the CG method and the BFGS method are described respectively. Numerical computations for two models including the benchmark Marmousi model with complex structure are implemented. The inversion results show that the BFGS-based algorithm behaves better in inversion than the CG-based algorithm does. Moreover, the good inversion result for Marmousi model with the BFGS-based algorithm suggests the quasi-Newton methods can provide an important tool for large-scale velocity inversion. More computations demonstrate the correctness and effectives of our inversion algorithms and code.

关键词： Finite Difference Acoustic Wave Equation full-waveform Inversion CG Method BFGS Method Marmousi Model

Calculation and application of full-wave airborne transient electromagnetic data in electromagnetic detection

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2019年第4期26卷 1011-1020页

作者： JI Yan-ju ZHU Yu YU Ming-mei LI Dong-sheng GUAN Shan-shan College of Instrumentation and Electrical Engineering Jilin University Key Laboratory of Earth Information Detection Instrumentation of Ministry of Education Jilin University StarNav Navigation Equipment Co. Ltd. National Geography Exploration Equipment Engineering Research Center Jilin University

Airborne electromagnetic transient method enjoys the advantages of high-efficiency and the high resolution of electromagnetic anomalies,especially suitable for mining detection around goaf areas and deep exploration of *** this paper,we calculated the full-wave airborne transient electromagnetic data,according to the result of numerical research,the advantage of switch-off time response in electromagnetic detection was proofed via ***,based on the full-wave airborne transient electromagnetic system developed by Jilin University(JLU-ATEMI),we proposed a method to compute the full-waveform electromagnetic(EM)data of 3D model using the FDTD approach and convolution algorithm,and verify the calculation by the response of homogenous ***,through comparison of switch-off-time response and off-time response,we studied the effect of ramp time on anomaly ***,we arranged two experimental electromagnetic detection,the results indicated that the switch-off-time response can reveal the shallow target more effectively,and the full-waveform airborne electromagnetic system is an effective technique for shallow target detection.

关键词： airborne electromagnetic transient method full-waveform FDTD approach convolution algorithm anomaly detection