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Nyström-based spectral clustering using airborne LiDAR point cloud data for individual tree segmentation

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International Journal of Digital Earth 2021年第10期14卷 1452-1476页

作者： Yong Pang Weiwei Wang Liming Du Zhongjun Zhang xiaojun liang Yongning Li Zuyuan Wang Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijingPeople’s Republic of China Key Laboratory of Forestry Remote Sensing and Information System of National Forestry and Grassland Administration BeijingPeople’s Republic of China College of Artificial Intelligence Beijing Normal UniversityBeijingPeople’s Republic of China College of Forestry Hebei Agricultural UniversityBaodingPeople’s Republic of China Department of Land Change Science Swiss Federal Institute for ForestSnow and Landscape Research WSLBirmensdorfSwitzerland

The spectral clustering method has notable advantages in *** the high computational complexity and time consuming limit its application in large-scale and dense airborne Light Detection and Ranging(LiDAR)point cloud *** proposed the Nyström-based spectral clustering(NSC)algorithm to decrease the computational *** novel NSC method showed accurate and rapid in individual tree segmentation using point cloud *** K-nearest neighbour-based sampling(KNNS)was proposed for the Nyström approximation of voxels to improve the *** NSC algorithm showed good performance for 32 plots in China and *** overall matching rate and extraction rate of proposed algorithm reached 69%and 103%.For all trees located by Global Navigation Satellite System(GNSS)calibrated tape-measures,the tree height regression of the matching results showed an value of 0.88 and a relative root mean square error(RMSE)of 5.97%.For all trees located by GNSS calibrated total-station measures,the values were 0.89 and 4.49%.The method also showed good performance in a benchmark dataset with an improvement of 7%for the average matching *** results demonstrate that the proposed NSC algorithm provides an accurate individual tree segmentation and parameter estimation using airborne LiDAR point cloud data.

关键词： Tree segmentation airborne LiDAR spectral clustering Nyström approximation sampling method

Mechanical and corrosion properties of N08825 CRA clad pipeline steel

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Baosteel Technical Research 2020年第3期14卷 23-30页

作者： liang xiaojun JIAO Sihai DING Jianhua Research Institute Baosha Iron&Steel Co.Ltd.Shanghri 201999China

Corrosion-resistant-alloy(CRA)clad steel combines the good mechanical properties of the base material and the excellent corrosion resistance of the cladding material,while also being much more economical than solid *** gas and oil fields can have high concentrations of H2 S,Cl-,CO2,and other chemicals,the pipes used to transport gas or oil must have high corrosion resistance and good mechanical *** N08825 nickel-based alloys with their excellent corrosion resistance can be a good cladding material in clad *** this paper,UNS N08825+X65 clad steel was produced by two different *** thermomechanical and quenching and tempering processes were investigated and their mechanical properties and corrosion resistance were *** corrosion and pitting corrosion tests were conducted and the results were evaluated.A high-pressure and high-temperature gas-field environment was also simulated to test the stress corrosion cracking of the *** results show that both clad plates have good mechanical properties and excellent corrosion *** experimental results were compared and the differences between the two processes were identified and discussed.

关键词： clad steel TMCP quenching tempering pipeline corrosion mechanical properties

Quantitative analysis of microstructure based on machine learning and its application in product research and development

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Baosteel Technical Research 2022年第2期16卷 23-34页

作者： XING Zhao HAO Yingmin liang xiaojun Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999.China

The material's microstructure is the output of the material composition and production process;simultaneously, it is the key factor in the material's performance and plays an important role in the material development *** digital features of microstructures that can be recognized by a computer are obtained through the quantitative description of the material's microstructure, and a mathematical model is used to associate them with the composition, process, and *** the evolution mechanism of microstructure features can help quickly to predict microstructure properties, which can be used to optimize the composition and process, accelerate product development iteration, and solve the long cycle problem of traditional research and development mode while lowering the high cost of high-frequency trial *** paper introduces the development and application of the combination of image knowledge, computer knowledge, and expert experience in the quantification of microstructures and the practical cases of recent studies of the Mask-Regions with Convolutional Neural Network Features(RCNN) method combined with machine learning in the digital research and development of heavy plates in Baosteel, and prospects the potential application of the quantification of microstructures of materials.

关键词： microstructure quantitative description digital research heavy plates Mask-RCNN

Application of the gradient-based watershed algorithm in M/A constituent identification

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Baosteel Technical Research 2022年第2期16卷 17-22页

作者： HAO Yingmin liang xiaojun XING Zhao Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

This paper reports the quantitative study of martensite/austenite(M/A)constituents in high-grade heavy steel plates using the gradient-based watershed *** with several other image segmentation algorithms,the gradient-based watershed algorithm can effectively remove noises in images with various qualities and identify M/A *** results prove that the gradient-based watershed algorithm is an effective method that can be used to digitize microstructures and integrate the data into Process Intelligent Data Application System(PIDAS).

关键词： M/A constituent microstructure digitizing gradient watershed image segmentation

Study on the interface of direct hot rolling titanium-clad steel plates

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Baosteel Technical Research 2017年第1期11卷 32-39页

作者： SUN Jifeng liang xiaojun JIAO Sihai Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201900China

In this study,the interface characteristics of a direct hot rolling titanium-clad steel plate were analyzed, and the mechanism of interface cracking was explored. The detrimental effect from the formation of TiFe ,TiC,and a Si-enriched layer on the bonding strength was clarified, and an industrial-scaled titanium-clad steel plate with shear strength over 200 MPa was produced with a carefully set schedule accordingly. It was found that hot rolling titanium-clad steel plates had a flat interface without obvious cracks. In the rolling process,both Ti and Fe atoms interdiflhsed,but Fe difthsed much faster than Ti. The Fe-diffused area consisted of three regions. After a high temperature heat treatment, the diffusion depth of Fe and Ti elements increased significantly and evident Si segregation and TiFe layers were identified. Thermal cracking initiated in the Si segregation layer and then propagated along the TiFe layer and Fe-diffused layer on the titanium side.

关键词： titanium-clad steel plate interface diffusion heat treatment

Investigation of separation phenomenon in high-toughness X70 thick-walled linepipe steel

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Baosteel Technical Research 2015年第3期9卷 35-40页

作者： DING Jianhua liang xiaojun JIAO Sihai Research Institute Baoshan Iron & Steel Co.Ltd.

Separation is a commonly observed phenomenon during drop weight tear testing in high-toughness linepipe steels. Severe separation is harmful because it may cause fracturing or bursting of pipes. In this study, a quantitative measurement of separation was proposed, and using this new method, a relationship between the separation and microstructure was determined and discussed. The microstructures observed using optical and scanning electron microscopy revealed that the separation was related to the mixed ferfitic and bainitic microstructures, or rather,it was related to the carbon enrichment in bainite.

关键词： linepipe steel DWTT separation bainite thermomechanical processing cleavage fracture

China’s larch stock volume estimation using Sentinel-2 and LiDAR data

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Geo-Spatial Information Science 2023年第3期26卷 392-405页

作者： Tao Yu Yong Pang xiaojun liang Wen Jia Yu Bai Yilin Fan Dongsheng Chen Xianzhao Liu Guang Deng Chonggui Li Xiangnan Sun Zhidong Zhang Weiwei Jia Zhonghua Zhao Xiao Wang Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijingChina Key Laboratory of Forestry Remote Sensing and Information System National Forestry and Grassland AdministrationBeijingChina Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration Research Institute of ForestryChinese Academy of ForestryBeijingChina College of Geomatics Xi’an University of Science and TechnologyXi’anChina Academy of Inventory and Planning National Forestry and Grassland AdministrationBeijingChina College of Forestry Hebei Agricultural UniversityBaodingChina College of Forestry Northeast Forestry UniversityHarbinChina Ecology and Nature Conservation Institute Chinese Academy of ForestryKey Laboratory of Forest Ecology and Environment of National Forestry and Grassland AdministrationBeijingChina

Forest Stock Volume(FSV)is one of the key indicators in forestry resource investigation and management on local,regional,and national *** by the saturation problems of optical satellite remote-sensing imagery in the retrieving of stock volume,and the high cost of Light Detection And Ranging(LiDAR)data,it is still challenging to estimate FSV in a large area using single-sensor remote-sensing *** this paper,a method integrated multispectral satellite imagery and LiDAR data was developed to map stock volume in a large area.A random forest model was adopted to estimate the stock volume of larch forest in China based on the training samples from the Airborne Laser Scanning(ALS)-derived stock volume and corresponding Sentinel-2 *** using National Forest Inventory(NFI)data,ALS-derived stock volume and ground investigation data demonstrated that the estimated stock volume had a high accuracy(R2=0.59,RMSE=59.69 m^(3)/ha,MD=39.96 m^(3)/ha when validated with NFI data;R2 ranged from 0.77 to 0.85,RMSE ranged from 38.68 m^(3)/ha to 67.38 m^(3)/ha,MD ranged from 24.90 m^(3)/ha to 37.27 m^(3)/ha when validated with ALS stock volume;R2=0.42,RMSE=79.10 m^(3)/ha,MD=62.06 m^(3)/ha when validated with field investigation data).Results of this paper indicated the applicability of estimating stock volume of larch forest in a large area by combining Sentinel-2 data and airborne LiDAR data.

关键词： Sentinel-2 LiDAR stock volume larch validation

Novel 64×2.5 Gb/s all-optical OFDM symbol generator based on triangle waveform driving-LiNbO_3 modulators

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Chinese Optics Letters 2010年第5期8卷 449-453页

作者：李源李蔚梁晓军杨克成乔耀军 Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Department of Computer Science and Technology Central China Normal University Key Laboratory of Information Photonics and Optical Communications Ministry of EducationBeijing University of Posts and Telecommunications

We propose a novel and simple all-optical 160-Gb/s orthogonal frequency division multiplexing（OFDM） symbol generator which is based on discrete triangle waveform driving-LiNbO_3 modulators to realize large-range linear optical *** entire system needs 64 discrete modulators：at the transmitter,a 2.5-Gb/s optical duobinary（ODB） modulator for data modulation and a 2.5-Gb/s triangle waveform driving-LiNbO_3 phase modulator for phase shift to generate each subcarrier;and at the receiver,a 2.5-GHz optical band pass filter（OBPF） using Faraday anomalous dispersion optical effect to separate *** bit error rate（BER） is observed after 1060 km of transmission without any dispersion compensation.

关键词： Bandpass filters Bit error rate Error compensation Frequency allocation Orthogonal frequency division multiplexing Orthogonal functions

The Occurrence of Separation in High Toughness Linepipe Steel During Drop Weight Tear Test

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The Occurrence of Separation in High Toughness Linepipe Stee...