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最小配置下相机位姿、焦距及径向畸变鲁棒高效解析方法

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激光与光电子学进展 2024年第16期61卷 261-269页

作者：张逸王宝琼张跃强胡彪陈文均刘肖琳于起峰深圳大学智能光测研究院广东深圳518000 深圳大学物理与光电工程学院广东深圳518000

基于3D/2.点对应的相机参数估计方法在众多视觉应用中占据着举足轻重的地位。perspective-n-points-focal-radial(Pn Pfr)方法根据3D/2.点对应,估计相机的位姿、焦距,以及径向畸变参数。针对其最小点数配置,即4点配置,也即P4Pfr问题,提... 详细信息

基于3D/2.点对应的相机参数估计方法在众多视觉应用中占据着举足轻重的地位。perspective-n-points-focal-radial(Pn Pfr)方法根据3D/2.点对应,估计相机的位姿、焦距,以及径向畸变参数。针对其最小点数配置,即4点配置,也即P4Pfr问题,提出一种鲁棒高效的解法。首先,基于针孔相机模型和径向畸变模型定义伪深度因子;然后,对3D点去中心化,消去平移向量,构建鲁棒的P4Pfr模型;最后,基于该模型参数化旋转矩阵,结合旋转矩阵约束求解。根据上述求解框架,分别针对普通配置和平面配置设计解法,前者通过Gr?ebner基多项式求解,后者采用一元六次方程求解。通过模拟仿真和数据集测试验证所提方法精度、鲁棒性,以及效率。实验结果表明,所提普通配置解法和平面配置解法分别具有同类最优和仅次于同类最优的鲁棒性,两者均有着同类最快的求解速度。

关键词：机器视觉相机标定摄影测量位姿估计径向畸变

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不同变质程度煤体表面液滴铺展特性实验研究

实验技术与管理 2024年第7期41卷 22-29页

作者：谢彪郁静静杨天艺张兴华李柏辰胡嘉奇太原理工大学安全与应急管理工程学院山西太原030024

为研究不同变质程度煤体表面液滴铺展特性,采用实验与数值计算相结合的方法,通过观察纯水液滴撞击煤体的动态铺展过程,探讨撞击高度对不同变质程度煤表面接触角及液滴铺展系数的影响,揭示不同变质程度煤体的润湿机理。测量4种不同煤质... 详细信息

为研究不同变质程度煤体表面液滴铺展特性,采用实验与数值计算相结合的方法,通过观察纯水液滴撞击煤体的动态铺展过程,探讨撞击高度对不同变质程度煤表面接触角及液滴铺展系数的影响,揭示不同变质程度煤体的润湿机理。测量4种不同煤质的静态接触角,实验结果表明:褐煤的润湿性最强,肥煤次之,无烟煤和焦煤的润湿性最差;观察纯水液滴碰撞不同煤样的动态变化发现,撞击高度与纯水液滴的铺展系数之间存在正相关关系;在相同高度下,纯水液滴铺展系数的变化均表现为先增大后降低再增大,最终趋于一个稳定状态。该研究结果可为矿井湿式除尘技术提供一定的理论参考。

关键词：撞击高度煤变质程度接触角铺展系数润湿机理

Investigation of the interior RC beam-column joints under monotonic antisymmetrical load

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1474-1494页

作者： Fei GAO Zhiqiang TANG biao hu Junbo CHEN Hongping Zhu Jian MA School of Civil Engineering and Mechanics Huazhong University of Science and TechnologyWuhan 430074China Guangdong Provincial Key L aboratory of Durability for Marine Civil Engineering Shenzhen UniversityShenzhen 518060China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

The paper presents numerical findings of reinforced concrete interior beam-column joints under monotonic antisymmetrical *** finite element models considered compression and tension damage were calibrated by test results in terms of the load-displacement,failure modes,and strains of longitudinal *** emphasis was put on studying the effects of hoop reinforcement ratio in joint core and the axial compression ratio on the responses of the *** results show that,in addition to the truss and strut-and-tie mechanisms,the confinement mechanism also existed in the joint core.A certain amount of stirrup is not only able to enhance the confinement in joint core,undertake a part of shear force and thus to increase the shear capacity,prevent the outward buckling of steel bars in column,improve the stress distribution in joint core,delay cracking and restrain the propagation of cracks,but also to increase the yield load,decrease the yield displacement of beam and improve the joint ***,excessive horizontal stirrups contribute little to the joint *** a certain range,larger axial compression ratio is beneficial for the joint mechanical behavior,while it is negative when axial compression ratio is too large.

关键词： RC beam-column joint reinforcement ratio in joint core axial compression ratio finite element test

SHRIMP zircon U-Pb dating from K-bentonite in the top of Ordovician of Wangjiawan Section,Yichang,hubei,China

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Science China Earth Sciences 2008年第4期51卷 493-498页

作者： hu Yanhua ZHOU JiBin SONG {2. LI Wei SUN WeiDong Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of GeochemistryChinese Academy of Sci-encesGuangzhou 510640China Beijing SHRIMP Center Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China School of Earth and Space Science University of Science and Technology of ChinaHefei 230026China Graduate University of the Chinese Academy of Sciences Beijing 100049China

The Global boundary Stratotype Section and Point (GSSP) for the base of the Hirnantian Stage (the latest stage of the Ordovician System) is defined at a point 0.39m below the base of the Kuanyinchiao Bed in the Wangjiawan North Section, which is the upper most "golden spike" of the Ordovician. However, this "golden spike" is lack of reliable geochronology data. This article gives a sensitive high resolution ion microprobe (SHRIMPII) zircon U-Pb dating for a K-bentonite sample from the Kuany-inchiao Bed in the Wangjiawan North Section. The age of the K-bentonite sample is 443.2.1.6 Ma, that is to say, the isotopic age of the uppermost of Hirnantian Stage, the point of Ordovician-Silurian boundary, should be near to, but slightly younger than 443.2.1.6 Ma. This age is identical to the Ordovi-cian-Silurian boundary age 443.7±1.5 Ma as declared by International Commission on Stratigraphy (ICS). So, this research provides some good geochronlogical data for the Hirnantian Stage and the Ordovician-Silurian boundary as well as the global correlation.

关键词： Hirnantian zircon SHRIMP bentonite Ordovician-Silurian boundary

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黄土的湿载结构性本构关系试验研究

贵州工程应用技术学院学报 2024年第3期42卷 51-60页

作者：罗爱忠方娟陈昌禄胡彪贵州工程应用技术学院土木建筑工程学院贵州毕节551700

为了验证所提出的黄土的湿载结构性本构关系,以及增湿和加载条件下黄土的结构性损伤演化规律,通过室内试验和数值模拟试验等方法研究了黄土的结构性力学特性及黄土的湿载结构性本构关系合理性。研究结果表明:黄土的湿载结构性本构关系... 详细信息

为了验证所提出的黄土的湿载结构性本构关系,以及增湿和加载条件下黄土的结构性损伤演化规律,通过室内试验和数值模拟试验等方法研究了黄土的结构性力学特性及黄土的湿载结构性本构关系合理性。研究结果表明:黄土的湿载结构性本构关系在描述饱和重塑黄土的力学特性方面与修正剑桥模型具有很好的一致性,模型能够模拟具有不同含水率的重塑黄土宏观力学反应,更重要的是该模型在模拟天然结构性黄土的力学特性方面,相较于剑桥模型及修正剑桥模型而言,具有明显的优势,能对所试验的天然结构性黄土的宏观力学特性给出准确的描述。通过黄土常规三轴试验结果和模型数值模拟结果的对比分析,验证了黄土的湿载结构性本构模型的合理性和准确性。

关键词：黄土结构性湿载结构性本构模型试验验证

Microstructure and corrosion behavior of Al3Ti/ADC12.composite modified with Sr

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International Journal of Minerals,Metallurgy and Materials 2018年第7期25卷 840-848页

作者： bao-biao yu hong yan qing-jie wu zhi hu fan-hui chen School of Mechanical and Electrical Engineering Nanchang UniversityNanchang 330031China

In this study, we investigated the effect of the addition of Sr （0wt%, 0. lwt%, 0.2.t%, and 0.3wt%） on the microstaalcture and cor- rosion behavior of A13Ti/ADC12.composite by optical microscopy, X-ray diffraction, sca^lning electron microscopy, mid energy diffraction spectroscopy. The results reveal that the c^-A1 phases were nearly spherical mid 40 gin in size and that the eutectic Si phases became round in the composite when the Sr content reached 0.2.t%. The A13Ti paxticles were distributed uniformly at the grain boundary. The results of the corrosion examination reveal that the A13Ti/ADC12.composite exhibited a minimum corrosion rate of 0.081 g.m 2.hl for an Sr content of 0.2.t%, which is two thirds of that of umnodified composite （0.134 g.m4.h 1）. This improved corrosion resistaalce was due to galvamc cor- rosion, which resulted from the low area ratio of the cathode to anode regions. This caused a low-density corrosion current in the composite, thereby yielding optimum corrosion resistmlce.

关键词： Sr modification A13Ti/ADC 12.composite microstxucture corrosion behavior

Integrable discretization of soliton equations via bilinear method and Backlund transformation

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Science China Mathematics 2015年第2期58卷 279-296页

作者： ZHANG Ying Nan CHANG Xiang Ke hu Juan hu Xing {2. TAM Hon-Wah Institute of Computational Mathematics and Scientific Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences Department of Applied Mathematics Zhejiang University of Technology Department of Computer Science Hong Kong Baptist University

We present a systematic procedure to derive discrete analogues of integrable PDEs via Hirota’s bilinear *** approach is mainly based on the compatibility between an integrable system and its B¨acklund *** apply this procedure to several equations,including the extended Korteweg-deVries(Kd V)equation,the extended Kadomtsev-Petviashvili(KP)equation,the extended Boussinesq equation,the extended Sawada-Kotera(SK)equation and the extended Ito equation,and obtain their associated semidiscrete *** the continuum limit,these differential-difference systems converge to their corresponding smooth *** these new integrable systems,their B¨acklund transformations and Lax pairs are derived.

关键词： integrable discretization bilinear method Backlund transformation

Effects of annealing temperature on electrochemical performance of SnSx embedded in hierarchical porous carbon with N-carbon coating by in-situ structural phase transformation as anodes for lithium ion batteries

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Journal of Materials Science & Technology 2021年第25期84卷 191-199页

作者： Qianqian hu biao Wang Shiyong Chang Chun Yang Yunjian hu Shubin Cao Jiqun Lu Lingzhi Zhang Ye Hong Guangzhou Institute of Energy Conversion Chinese Academy of SciencesCAS Key Laboratory of Renewable EnergyGuangdong Provincial Key Laboratory of New and Renewable Energy Research and DevelopmentGuangzhouGuangdong 510640China GAC Automotive Research&Development Center Guangzhou 511434China University of Chinese Academy of Sciences Beijing 100049China Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215123China Industrial Training Center Guangdong Polytechnic Normal University510665China

Tuned tin chalcogenides rooted in hierarchical porous carbon(HPC)with N-carbon coating layers are prepared by thermal shock under various temperatures(denoted as HPC-SnS_(2.-PAN-Various T).With the increase of annealing temperature,the morphology and phase structure of Sn S_(2.,as well as the cyclization degree of polyacrylonitrile(PAN),are significantly changed,which leads to the formation of rod-like Sn S and ordered structure of conductive N-carbon *** combining HPC,N-carbon coating derived from the cyclization of PAN,with 1D Sn S nanorods generated from structural phase transformation of SnS_(2.,the optimized composite(HPC-SnS_(2.-PAN-500)as anode for lithium ion batteries(LIBs)provides buffer space for volume changes during alloying/dealloying process,builds a highly conductive network as well as decreases irreversible capacity from solid electrolyte interphase and enhances the ion/electron *** to the above merits from composition regulation and architecture modification by sulfur depletion and PAN cyclization,this target anode exhibits an extraordinary cycling stability with a high specific capacity of 652.5 m A h/g at 0.5 A/g after 900 *** suggests that rod-like Sn S embedded in HPC with cyclized PAN layers by thermal treatment approach renders a potential structural design of anode materials for LIBs.

关键词： Hierarchical porous carbon SnSx Conducting medium Cycling stability Lithium ion batteries

An extended processing scheme for coherent integration and parameter estimation based on matched filtering in passive radar

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第11期15卷 1071-1085页

作者： Xin GUAN Li-hua ZHONG Dong-hui hu Chi-biao DING Key Laboratory of Technology in Geo-spatial Information Processing and Application System Institute of Electronics Chinese Academy of Sciences University of Chinese Academy of Sciences

In passive radars, coherent integration is an essential method to achieve processing gain for target detection. The cross ambiguity function(CAF) and the method based on matched filtering are the most common approaches. The method based on matched filtering is an approximation to CAF and the procedure is:(1) divide the signal into snapshots;(2. perform matched filtering on each snapshot;(3) perform fast Fourier transform(FFT) across the snapshots. The matched filtering method is computationally affordable and can offer savings of an order of 1000 times in execution speed over that of CAF. However, matched filtering suffers from severe energy loss for high speed targets. In this paper we concentrate mainly on the matched filtering method and we use keystone transform to rectify range migration. Several factors affecting the performance of coherent integration are discussed based on the matched filtering method and keystone transform. Modified methods are introduced to improve the performance by analyzing the impacts of mismatching, precision of the keystone transform, and discretization. The modified discrete chirp Fourier transform(MDCFT) is adopted to rectify the Doppler expansion in a multi-target scenario. A novel velocity estimation method is proposed, and an extended processing scheme presented. Simulations show that the proposed algorithms improve the performance of matched filtering for high speed targets.

关键词： Keystone transform Matched filtering MDCFT Mismatching Passive radar Velocity estimation