检索结果-南通市图书馆

Theoretical and experimental study on broadband terahertz atmospheric transmission characteristics

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第1期26卷 597-602页

作者： Shi-Bei Guo Kai Zhong Mao-Rong Wang Chu Liu Yong Xiao Wen-Peng Wang De-Gang Xu Jian-Quan Yao Institute of Laser and Opto-electronics College of Precision Instrument and Opto-electronics Engineering Tianjin University Tianjin 300072 China key laboratory of Opto-electronics Information technology (Ministry of Education) Tianjin University Tianjin 300072 China national key laboratory of science and technology on millimeter-wave remote sensing Beijing 100039 China

Broadband terahertz（THz） atmospheric transmission characteristics from 0 to 8 THz are theoretically simulated based on a standard Van Vleck–Weisskopf line shape, considering 1696 water absorption lines and 298 oxygen absorption *** influences of humidity, temperature, and pressure on the THz atmospheric absorption are analyzed and experimentally verified with a Fourier transform infrared spectrometer（FTIR） system, showing good consistency. The investigation and evaluation on high-frequency atmospheric windows are good supplements to existing data in the low-frequency range and lay the foundation for aircraft-based high-altitude applications of THz communication and radar.

关键词： terahertz atmospheric propagation line absorption continuum absorption

Geospatial technologies for Chang’e-3 and Chang’e-4 lunar rover missions

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information science 2020年第1期23卷 87-97页

作者： Kaichang Di Zhaoqin Liu Wenhui Wan Man Peng Bin Liu Yexin Wang Sheng Gou Zongyu Yue State key laboratory of remote sensing science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina

This paper presents a brief overview of the geospatial technologies developed and applied in Chang’e-3 and Chang’e-4 lunar rover *** mapping techniques were used to produce topographic products of the landing site with meter level resolution using orbital images before landing,and to produce centimeter-resolution topographic products in near real-time after *** positioning techniques were used to determine the locations of the two landers using descent images and orbital basemaps immediately after *** surface operations,visual-positioning-based rover localization was performed routinely at each waypoint using Navcam *** topographic analysis and rover localization results directly supported waypoint-to-waypoint path planning,science target selection and scientific investigations.A GIS-based digital cartography system was also developed to support rover teleoperation.

关键词： Geospatial technology lunar rover landing site mapping topographic analysis rover localization and navigation

Automated Rock Detection and Shape Analysis from Mars Rover Imagery and 3D Point Cloud 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

Journal of Earth science 2013年第1期24卷 125-135页

作者：邸凯昌岳宗玉刘召芹王树良 State key laboratory of remote sensing science Institute of Remote Sensing Applications Chinese Academy Sciences School of Software Beijing Institute of Technology

A new object-oriented method has been developed for the extraction of Mars rocks from Mars rover data. It is based on a combination of Mars rover imagery and 3D point cloud data. First, Navcam or Pancam images taken by the Mars rovers are segmented into homogeneous objects with a mean-shift algorithm. Then, the objects in the segmented images are classified into small rock candidates, rock shadows, and large objects. Rock shadows and large objects are considered as the regions within which large rocks may exist. In these regions, large rock candidates are extracted through ground-plane fitting with the 3D point cloud data. Small and large rock candidates are combined and postprocessed to obtain the final rock extraction results. The shape properties of the rocks （angularity, circularity, width, height, and width-height ratio） have been calculated for subsequent ~eological studies.

关键词： Mars rover rock extraction rover image 3D point cloud data.

Assessment and analysis of microwave emissivity and transmissivity of a deciduous forest towards the estimate of vegetation biomass

在线全文

学校读者我要写书评

暂无评论

science China Earth sciences 2014年第3期57卷 534-541页

作者： ZHANG ZhongJun YU XianChuan ZHAO ShaoJie CHAI LinNa College of Information science and technology Beijing Normal University State key laboratory of remote sensing science

Forests play an important role in the global carbon cycle and have a potential impact on global climatic *** forest biomass is of considerable importance in understanding the hydrological *** of the problem of dense forest cover,no reliable method with which to retrieve soil moisture in forest areas from the microwave emission signature has been *** of these issues relate to the microwave emissivity and transmissivity characteristics of a *** microwave emission contribution received by a sensor above a forest canopy comes from both the soil surface and the vegetation *** analyze the relationship of forest biomass and forest emission and transmissivity,a high-order emission model,the matrix-doubling model,which consists of both soil and vegetation models,was developed and then validated for a young deciduous forest stand in a field *** simulate the emissivity and transmissivity of a deciduous forest in the L and X bands using the matrix-doubling model,the parameters of components of deciduous trees when the leaf area index varies from 1 to10 were generated by an L-system and a forest growth *** emissivity and transmissivity of a forest and the relationships of these parameters to forest biomass are presented and analyzed in this *** in the L band when the leaf area index is less than 6 and at viewing angles less than 40°,and transmissivity in the L band are the most sensitive parameters in deciduous forest biomass estimation.

关键词： forest biomass matrix-doubling microwave emission transmissivity L-system

An improved constraint method in optimal estimation of CO2 from GOSAT SWIR observations

在线全文

学校读者我要写书评

暂无评论

science China Earth sciences 2017年第2期60卷 286-296页

作者： ZOU MingMin CHEN LiangFu LI ShenShen FAN Meng TAO JinHua ZHANG Ying State key laboratory of remote sensing science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing 100101 China

We propose an algorithm that combines a pre-processing step applied to the a priori state vector prior to retrievals, with the modified damped Newton method （MDNM）, to improve convergence. The initial constraint vector pre-processing step updates the initial state vector prior to the retrievals if the algorithm detects that the initial state vector is far from the true state vector in extreme cases where there are CO2 emissions. The MDNM uses the Levenberg-Marquardt parameter ~,, which ensures a positive Hessian matrix, and a scale factor a, which adjusts the step size to optimize the stability of the convergence. While the algorithm iteratively searches for an optimized solution using observed spectral radiances, MDNM adjusts parameters ）, and a to achieve stable convergence. We present simulated retrieval samples to evaluate the performance of our algorithm and comparing it to existing methods. The standard deviation of our retrievals adding random noise was less than 3.8 ppmv. After pre-processing the initial estimate when it was far from the true value, the CO2 retrieval errors in the boundary layers were within 1.2 ppmv. We tested the MDNM algorithm＇s performance using GOSAT Llb data with cloud screening. Our preliminary validations comparing the results to TCCON FTS measurements showed that the average bias was less than 1.8 ppm and the correlation coefficient was approximately 0.88, which was larger than for the GOSAT L2 product.

关键词： Retrieve Optimal estimation CO2 GOSAT

Point pattern matching based on kernel partial least squares

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2011年第1期9卷 36-40页

作者：延伟东田铮潘璐璐温金环 School of science Northwestern Polytechnical University State key laboratory of remote sensing science Institute of Remote Sensing ApplicationsChinese Academy of Sciences

Point pattern matching is an essential step in many image processing applications. This letter investigates the spectral approaches of point pattern matching, and presents a spectral feature matching algorithm based on kernel partial least squares （KPLS）. Given the feature points of two images, we define position similarity matrices for the reference and sensed images, and extract the pattern vectors from the matrices using KPLS, which indicate the geometric distribution and the inner relationships of the feature points. Feature points matching are done using the bipartite graph matching method. Experiments conducted on both synthetic and real-world data demonstrate the robustness and invariance of the algorithm.

关键词： Algorithms Image processing Probability distributions

Image registration based on matrix perturbation analysis using spectral graph

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2009年第11期7卷 996-1000页

作者：冷成财田铮李婧丁明涛 School of science Northwestern Polytechnical University State key laboratory of remote sensing science Institute of Remote Sensing ApplicationsChinese Academy of Sciences

We present a novel perspective on characterizing the spectral correspondence between nodes of the weighted graph with application to image registration. It is based on matrix perturbation analysis on the spectral graph. The contribution may be divided into three parts. Firstly, the perturbation matrix is obtained by perturbing the matrix of graph model. Secondly, an orthogonal matrix is obtained based on an optimal parameter, which can better capture correspondence features. Thirdly, the optimal matching matrix is proposed by adjusting signs of orthogonal matrix for image registration. Experiments on both synthetic images and real-world images demonstrate the effectiveness and accuracy of the proposed method.

关键词： Image registration based on matrix perturbation analysis using spectral graph THH LH VHH SAR Ga

Assimilation of HY-2A scatterometer sea surface wind data in a 3DVAR data assimilation system-A case study of Typhoon Bolaven

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth science 2015年第2期9卷 192-201页

作者： Yi YU Weimin ZHANG Zhongyuan WU Xiaofeng YANG Xiaoqun CAO Mengbin ZHU national University of Defense technology Changsha 410073 China State key laboratory of remote sensing science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing 100101 China

The scatterometer （SCAT） on-board China＇s HY-2A satellite has the capability to provide high resolution wind vector information over the global ocean surface. These wind vector data produced by the HY-2A scatterometer （HY-2A SCAT） are available to the data assimilation system with real-time information of high accuracy. In this paper, two experiments are designed to investigate the impact of HY-2A SCAT data in the three- dimensional variational assimilation system for the Weather Research and Forecast model （WRF 3DVAR）. The powerful Typhoon Bolaven, which struck South Korea in August 2012, is selected for this case study. The results clearly demonstrate that HY-2A SCAT data can effectively complement the scarce observations over the ocean surface and improve the prediction of the wind and pressure fields of a typhoon. The case study of Typhoon Bolaven exhibits the significant and positive impact of HY- 2A SCAT data on the numerical prediction of the tropical cyclone track.

关键词： HY-2A scatterometer data assimilation seasurface wind 3DVAR

Spectral feature matching based on partial least squares

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2009年第3期7卷 201-205页

作者：延伟东田铮潘璐璐丁明涛 School of science Northwestern Polytechnical University State key laboratory of remote sensing science Institute of Remote Sensing ApplicationsChinese Academy of Sciences

We investigate the spectral approaches to the problem of point pattern matching, and present a spectral feature descriptors based on partial least square （PLS）. Given keypoints of two images, we define the position similarity matrices respectively, and extract the spectral features from the matrices by PLS, which indicate geometric distribution and inner relationships of the keypoints. Then the keypoints matching is done by bipartite graph matching. The experiments on both synthetic and real-world data corroborate the robustness and invariance of the algorithm.

关键词： Content based retrieval Curve fitting Drug products Graph theory Image processing Pattern matching