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Tracking multiple people under occlusion and across cameras using probabilistic models

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第7期10卷 985-996页

作者： Xuan-he WANG ji-lin liu Institute of Information and Communication Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Laboratory of lnformation Network Technology Hangzhou 310027 China

Tracking multiple people under occlusion and across cameras is a challenging question for discussion. Furthermore, the cameras in this study are used to extend the field of view, which are distinguished from the same field of view. Such corre- spondence between multiple cameras is a burgeoning research subject in the area of computer vision. This paper effectively solves the problems of tracking multiple people who pass from one camera to another and segmenting people under occlusion using probabilistic models. The probabilistic models are composed of blob model, motion model and color model, which make the most of the space, motion and color information. First, we present a color model that uses maximum likelihood estimation based on non-parametric kernel density estimation. Second, we introduce a blob model based on mean shift, which segments the body into many regions according to the color of each person in order to spatially localize the color features corresponding to the way people are dressed. Clothes can be any mixture of colors. Third, we bring forward a motion model based on statistical probability which indicates the movement position of the same person between two successive frames in a single camera. Finally, we effectively unify the three models into a general probabilistic model and attain a maximization likelihood probability image, which is used to segment the foreground region under occlusion and to match people across multiple cameras.

关键词： Color model Motion model Blob model People occlusion People tracking Kernel density estimation

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A reweighted damped singular spectrum analysis method for robust seismic noise suppression

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Petroleum Science 2024年第3期21卷 1671-1682页

作者： Wei-lin Huang Yan-Xin Zhou Yang Zhou Wei-jie liu ji-Dong Li State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing2249China SINOPEC Petroleum Exploration and Production Research Institute Beijing102206China SINOPEC Geophysical Research Institute Nanjing211103jiangsuChina

(Multichannel)Singular spectrum analysis is considered as one of the most effective methods for seismic incoherent noise *** utilizes the low-rank feature of seismic signal and regards the noise suppression as a low-rank reconstruction ***,in some cases the seismic geophones receive some erratic disturbances and the amplitudes are dramatically larger than other *** presence of this kind of noise,called erratic noise,makes singular spectrum analysis(SSA)reconstruction unstable and has undesirable effects on the final *** robustify the low-rank reconstruction of seismic data by a reweighted damped SSA(RD-SSA)*** incorporates the damped SSA,an improved version of SSA,into a reweighted *** damping operator is used to weaken the artificial disturbance introduced by the low-rank projection of both erratic and random *** central idea of the RD-SSA method is to iteratively approximate the observed data with the quadratic norm for the first iteration and the Tukeys bisquare norm for the rest *** RD-SSA method can suppress seismic incoherent noise and keep the reconstruction process robust to the erratic *** feasibility of RD-SSA is validated via both synthetic and field data examples.

关键词： Singular spectrum analysis Damping operator Seismic erratic noise Seismic signal processing Robust low-rank reconstruction

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Effect of nano-graphite on mechanical properties and oxidation resistance of ZrB_(2)-SiC-graphite electrode ceramics

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Journal of Iron and Steel Research(International) 2024年第6期31卷 1502-1513页

作者： Bo-lin Yang Chang-liu Kuang Zheng-long liu Chao Yu Cheng-ji Deng Jun Ding The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina

ZrB_(2)-based ceramic composites were prepared by spark plasma sintering using ZrB_(2) powder prepared by molten salt method as raw material and SiC and nano-graphite as *** effects of nano-graphite addition on the physical properties and oxidation resistance of ZrB_(2)-based ceramic samples were *** results show that the addition of an appropriate amount of nano-graphite can effectively improve the density of ZrB_(2)-based ceramic composites and improve the physical properties of the *** flexural strength of the ceramic sample with 8 vol.%nano-graphite reached 418.54 MPa,which was 53.14% higher than that of ZrB_(2)-SiC ceramic material(273.31 MPa),and its oxidation resistance was also significantly *** demonstrats that the addition of an appropriate amount of nano-graphite can effectively improve the physical properties and oxidation resistance of ZrB_(2)-SiC ceramic *** prolonging its service life in application and promoting the development of ZrB_(2)-based ceramic composites,it is of great significance for clean steel smelting.

关键词： ZrB_(2)-SiC-graphite electrode ceramic ZrB_(2)-based ceramic composite Nano-graphite Physical property Oxidation resistance

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MAX-DOAS and in-situ measurements of aerosols and trace gases over Dongying,China:Insight into ozone formation sensitivity based on secondary HCHO

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Journal of Environmental Sciences 2024年第1期135卷 656-668页

作者： Xiaojun Zheng Zeeshan Javed Cheng liu Aimon Tanvir Osama Sandhu Haoran liu Xiangguang ji Chengzhi Xing Hua lin Daolin Du Institute of Environment and Ecology School of the Environment and Safety EngineeringJiangsu UniversityZhenjiang 212013China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Key Laboratory of Environmental Optics&Technology Anhui Institute of Optics and Fine MechanicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes University of Science and Technology of ChinaHefei 230026China Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Department of Environmental Science and EngineeringFudan UniversityShanghai 200433China National Agromet Center Pakistan Meteorological DepartmentIslamabad 44000Pakistan Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China Information Materials and Intelligent Sensing Laboratory of Anhui Province Anhui UniversityHefei 230601China School of Environmental Science and Optoelectronic Technology University of Science and Technology of ChinaHefei 230026China

This study presents a comprehensive overview of the atmospheric pollutants including Sulfur dioxide(SO_(2)),Nitrogen dioxide(NO_(2)),Formaldehyde(HCHO),Particulate Matter PM;PM_(10):diameter≤10μm,and PM_(2.5):diameter≤2.5μm,and Ozone(O_(3)),over Dongying(Shandong Province)from March-April 2018 and September-October 2019 by employing ground-based Multiple Axis Differential Optical Absorption Spectroscopy(MAX-DOAS)observations along with the in-situ measurements attained by the national air quality monitoring *** concentrations of SO_(2)and NO_(2)were under the acceptable level,while both PM_(2.5),and PM_(10)were higher than the safe levels as prescribed by national and international air quality *** results depict that 21%of the total observation days were found to be complex polluted days(PM_(2.5)>35μg/m^(3) and O_(3)>160μg/m^(3)).The secondary HCHO was used for accurate analysis of O_(3)sensitivity.A difference of 11.40%and 10%during March-April 2018 and September-October 2019 respectively in O_(3)sensitivity was found between HCHO_(total)/NO_(2)and HCHO_(sec)/NO_(2).The results indicate that primary HCHO have significant contribution in HCHO.O_(3)formation predominantly remained to be in VOC-limited and transitional regime during March-April 2018 and September-October 2019 in *** results imply that concurrent control of both NO_(x) and VOCs would benefit in ozone ***,the criteria pollutants(PM,SO_(2),and NO_(2))depicted strong correlations with each other except for O_(3)for which weak correlation coefficient was obtained with all the *** study will prove to be baseline for designing of air pollution control strategies.

关键词： MAX-DOAS Trace gases Ozone sensitivity Secondary HCHO Complex Pollution

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Environment map building and localization for robot navigation based on image sequences

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 489-499页

作者： Ye-hu SHEN ji-lin liu Xin DU Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

SLAM is one of the most important components in robot navigation. A SLAM algorithm based on image sequences captured by a single digital camera is proposed in this paper. By this algorithm, SIFT feature points are selected and matched between image pairs sequentially. After three images have been captured, the environment’s 3D map and the camera’s positions are initialized based on matched feature points and intrinsic parameters of the camera. A robust method is applied to estimate the position and orientation of the camera in the forthcoming images. Finally, a robust adaptive bundle adjustment algorithm is adopted to optimize the environment’s 3D map and the camera’s positions simultaneously. Results of quantitative and qualitative experiments show that our algorithm can reconstruct the environment and localize the camera accurately and efficiently.

关键词：单眼视力信息处理数字立势图图象序列

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Using concurrent lines in central catadioptric camera calibration

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第3期12卷 239-249页

作者： Lei ZHANG Xin DU ji-lin liu Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

Central catadioptric cameras have been extensively adopted in robotics and surveillance due to their extensive field of *** attain precise 3D information in these applications,it is important to calibrate the catadioptric cameras *** existing calibration techniques either require prior knowledge of the mirror types,or highly depend on a conic estimation procedure,which might be ruined if there are only small portions of the conic visible on calibration *** this paper,we design a novel planar pattern with concurrent lines as a calibration rig,which is more robust in conic estimation since the relationship among lines is taken into *** on the line properties,we propose a rough-to-fine approach suitable for the new planar pattern to calibrate central catadioptric *** method divides the nonlinear optimization calibration problem into several linear sub-problems that are much more robust against *** calibration method can estimate intrinsic parameters and the mirror parameter simultaneously and accurately,without a priori knowledge of the mirror *** performance is demonstrated by both simulation and a real hyperbolic catadioptric imaging system.

关键词： Catadioptric Calibration Concurrent lines Conic estimation

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Single-phase evolution path to new record efficiency of kesterite solar cells

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Science China Chemistry 2024年第2期67卷 420-421页

作者： Yixiong ji Fangyang liu School of Metallurgy and Environment Central South UniversityChangsha410083China ARC Centre of Excellence in Exciton Science School of ChemistryUniversity of Melbourne3010MelbourneVictoriaAustralia

Over the past few years, there have been significant advancements in uncovering previously sealed records in the kesterite solar cell. This also has led to substantial growth marked by multiple groups achieving successive efficiency breakthroughs, shining a renewed spotlight on this promising photovoltaic material that had previously been overlooked due to its low efficiency.

关键词： breakthrough sealed successive

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Robust water hazard detection for autonomous off-road navigation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 786-793页

作者： Tuo-zhong YAO Zhi-yu XIANG ji-lin liu Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

Existing water hazard detection methods usually fail when the features of water surfaces are greatly changed by the surroundings, e.g., by a change in illumination. This paper proposes a novel algorithm to robustly detect different kinds of water hazards for autonomous navigation. Our algorithm combines traditional machine learning and image segmentation and uses only digital cameras, which are usually affordable, as the visual sensors. Active learning is used for automatically dealing with problems caused by the selection, labeling and classification of large numbers of training sets. Mean-shift based image segmentation is used to refine the final classification. Our experimental results show that our new algorithm can accurately detect not only ‘common’ water hazards, which usually have the features of both high brightness and low texture, but also ‘special’ water hazards that may have lots of ripples or low brightness.

关键词：自主导航水害探测危险鲁棒图像分割机器学习视觉传感器

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Vision based terrain reconstruction for planet rover using a special binocular bundle adjustment

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1341-1350页

作者： Min-yi SHEN Zhi-yu XIANG ji-lin liu Institute of Information and Communication Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Laboratory of Information Network Technology Zhejiang University Hangzhou 310027 China

This paper presents a pure vision based technique for 3D reconstruction of planet terrain. The reconstruction accuracy depends ultimately on an optimization technique known as 'bundle adjustment'. In vision techniques, the translation is only known up to a scale factor, and a single scale factor is assumed for the whole sequence of images if only one camera is used. If an extra camera is available, stereo vision based reconstruction can be obtained by binocular views. If the baseline of the stereo setup is known, the scale factor problem is solved. We found that direct application of classical bundle adjustment on the constraints inherent between the binocular views has not been tested. Our method incorporated this constraint into the conventional bundle adjustment method. This special binocular bundle adjustment has been performed on image sequences similar to planet terrain circumstances. Experimental results show that our special method enhances not only the localization accuracy, but also the terrain mapping quality.

关键词： 3D重构 BBA 信息处理计算机技术

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Hydrogel bioadhesives harnessing nanoscale phase separation for Achilles tendon repairing

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Nano Research 2024年第2期17卷 778-787页

作者： Jun Zhang Xingmei Chen jingseng lin Pei Zhang Iek Man Lei Yue Tao jiajun Zhang Tian Luo ji liu Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Research and Innovation Center SKG Health TechnologyShenzhen 518000China SAFE(Shenzhen)Medical Technology Company Limited Shenzhen 518000China Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Department of Mechanical and Energy EngineeringSouthern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Human-Augmentation and Rehabilitation Robotics in Universities Southern University of Science and TechnologyShenzhen 518055China

Repairing Achilles tendon has emerged as a long-standing challenge in the orthopaedic *** suture is the gold standard for re-attaching and repairing the fractured Achilles tendons in clinical surgeries,it is still subjected to numerous adverse side-effects,including chronic inflammatory,tendon tissue re-rupture,scar formation,and post-surgical peritendinous *** this work,we develop a class of hydrogel bioadhesives with tailored nanoscale phase separation for Achilles tendon *** address the existing limitations of sutures,our hydrogel bioadhesives encompass three core functionalities:(i)instant and tough adhesion to Achilles tendon tissues,(ii)extraordinary long-term adhesion robustness under wet and dynamic in vivo conditions,and(iii)anti-postsurgical peritendinous *** our hydrogel bioadhesives with sutures,such kind of integrated approach enables a conformable yet robust biointerface with the tendon tissues,and prevents the fibroblast migration and formation of connective tissues,thus facilitating the tendon *** hydrogel bioadhesives reported here open up new opportunities for the repairing of fractured Achilles tendons in diverse and complicated clinical scenarios.

关键词： hydrogels phase separation bioadhesion robustness tendon repairing

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