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Circular object recognition based on shape parameters

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Journal of Systems Engineering and Electronics 2007年第2期18卷 199-204页

作者： chen aijun Li Jinzong Zhu Bing Inst. of Image Information Technology and Engineering Harbin Inst. of Technology Harbin 150001 P. R. China

To recognize circular objects rapidly in satellite remote sensing imagery, an approach using their geometry properties is presented. The original image is segmented to be a binary one by one dimension maximum entropy threshold algorithm and the binary image is labeled with an algorithm based on recursion technique. Then, shape parameters of all labeled regions are calculated and those regions with shape parameters satisfying certain conditions are recognized as circular objects. The algorithm is described in detail, and comparison experiments with the randomized Hough transformation （RHT） are also provided. The experimental results on synthetic images and real images show that the proposed method has the merits of fast recognition rate, high recognition efficiency and the ability of anti-noise and anti-jamming. In addition, the method performs well when some circular objects are little deformed and partly misshapen.

关键词： Circular object Pattern recognition Shape parameter Region labeling Image segmentation

Analysis of dynamic stress intensity factors of thick-walled cylinder under internal impulsive pressure

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Acta Mechanica Sinica 2009年第6期25卷 803-809页

作者： aijun chen Lianfang Liao Dingguo Zhang School of Sciences Nanjing University of Scienceand Technology 210094 Nanjing China Shenyang Aero-engine Research Institute 110015 Shenyang China

Dynamic stress intensity factors are evaluated for thick-walled cylinder with a radial edge crack under internal impulsive pressure. Firstly, the equation for stress intensity factors under static uniform pressure is used as the reference case, and then the weight function for a thick-walled cylinder containing a radial edge crack can be worked out. Secondly, the dynamic stresses in uncracked thick-walled cylinders are solved under internal impulsive pressure by using mode shape function method. The solution consists of a quasi-static solution satisfying inhomogeneous boundary conditions and a dynamic solution satisfying homogeneous boundary condi- tions, and the history and distribution of dynamic stresses in thick-walled cylinders are derived in terms of Fourier-Bessel series. Finally, the dynamic stress intensity factor equations for thick-walled cylinder containing a radial edge crack sub- jected to internal impulsive pressure are given by dynamic weight function method. The finite element method is utilized to verify the results of numerical examples, showing the validity and feasibility of the proposed method.

关键词： Thick-walled cylinder . Cracks .Dynamic stress intensity factors . Weight function methodMode shape function

Statistical Modeling with a Hidden Markov Tree and High-resolution Interpolation for Spaceborne Radar Reflectivity in the Wavelet Domain

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Advances in Atmospheric Sciences 2020年第12期37卷 1359-1374页

作者： Leilei KOU Yinfeng JIANG aijun chen Zhenhui WANG Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science&TechnologyNanjing 210044China Nanjing University of Information Science&Technology Nanjing 210044China

With the increasing availability of precipitation radar data from space,enhancement of the resolution of spaceborne precipitation observations is important,particularly for hazard prediction and climate modeling at local scales relevant to extreme precipitation intensities and *** this paper,the statistical characteristics of radar precipitation reflectivity data are studied and modeled using a hidden Markov tree(HMT)in the wavelet ***,a high-resolution interpolation algorithm is proposed for spaceborne radar reflectivity using the HMT model as prior *** to the small and transient storm elements embedded in the larger and slowly varying elements,the radar precipitation data exhibit distinct multiscale statistical properties,including a non-Gaussian structure and scale-to-scale *** HMT model can capture well the statistical properties of radar precipitation,where the wavelet coefficients in each sub-band are characterized as a Gaussian mixture model(GMM),and the wavelet coefficients from the coarse scale to fine scale are described using a multiscale Markov *** state probabilities of the GMM are determined using the expectation maximization method,and other parameters,for instance,the variance decay parameters in the HMT model are learned and estimated from high-resolution ground radar reflectivity *** the prior model,the wavelet coefficients at finer scales are estimated using local Wiener *** interpolation algorithm is validated using data from the precipitation radar onboard the Tropical Rainfall Measurement Mission satellite,and the reconstructed results are found to be able to enhance the spatial resolution while optimally reproducing the local extremes and gradients.

关键词： spaceborne precipitation radar hidden Markov tree model Gaussian mixture model interpolation in the wavelet domain multiscale statistical properties

The Application of Curriculum Ideological and Political Cases in the Teaching of Road Survey and Design

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Journal of Educational Theory and Management 2022年第1期6卷 73-80页

作者： aijun chen Bai Yang Xianyuan Tang Junhua chen Guilin University of Electronic Technology School of Architecture and Transportation EngineeringGuilinGuangxi541004China

Ideological and political construction of curriculum is the key link to implement the fundamental task of moral *** on the training objectives of civil engineering professionals in the new era,combined with the teaching concepts of moral education and student-centered education,the teaching objectives for the course of road survey and design have been *** implementation plan of ideological and political education has been put into practice by involving excellent engineering cases,stories of outstanding figures in this field,traffic accidents,design concepts and technological innovation to explore the methods of integrating ideological and political cases into curriculum teaching for a continuous improvement of the promotion of curriculum ideological and political education to the teaching quality of professional courses.

关键词： Road surveying and design Ideological and political education Case Integration

基于非傅里叶热传导对热冲击下带裂纹厚壁圆筒的分析

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维普期刊数据库

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振动与冲击 2020年第4期39卷 278-283,298页

作者：张彦博陈爱军南京理工大学理学院南京210094 瞬态冲击技术重点实验室北京102202

随着科学技术、工业水平的发展,传统的傅里叶导热在极端条件下不再适用。基于双曲型单相延迟非傅里叶热传导方程,推导了热冲击下有限元方程,编写了有限元算法程序,研究了在热冲击载荷下含裂纹厚壁圆筒结构的热力学响应,计算出厚壁圆筒... 详细信息

随着科学技术、工业水平的发展,传统的傅里叶导热在极端条件下不再适用。基于双曲型单相延迟非傅里叶热传导方程,推导了热冲击下有限元方程,编写了有限元算法程序,研究了在热冲击载荷下含裂纹厚壁圆筒结构的热力学响应,计算出厚壁圆筒在非经典传热条件下的温度场、位移场和裂纹尖端应力强度因子的数值解,分析不同热冲击载荷、不同裂纹长度、不同相位延迟下非傅里叶热传导的波动性效应以及温度应力强度因子的变化,得到相应的结论。为非经典工程条件下,带裂纹厚壁圆筒构件的可靠性以及构件的优化设计提供了数值上的参考。

关键词：非傅里叶热传导热冲击厚壁圆筒裂纹温度应力强度因子有限元分析

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热冲击下带裂纹功能梯度厚壁圆筒的分析

振动与冲击 2017年第15期36卷 64-70,76页

作者：彭亦鹏陈爱军南京理工大学理学院南京210094

针对功能梯度材料热冲击下的断裂问题,对功能梯度材料的材料参数分类进行加权处理,建立带裂纹功能梯度厚壁圆筒的模型;给出热量平衡方程与边界条件,建立相关问题的有限元分析格式;改进Calahan算法以适用于带状稀疏矩阵的一阶非齐次常微... 详细信息

针对功能梯度材料热冲击下的断裂问题,对功能梯度材料的材料参数分类进行加权处理,建立带裂纹功能梯度厚壁圆筒的模型;给出热量平衡方程与边界条件,建立相关问题的有限元分析格式;改进Calahan算法以适用于带状稀疏矩阵的一阶非齐次常微分方程组,完善温度场的求解过程,计算了裂纹尖端的温度应力强度因子,并且分析功能梯度材料组分构成对温度应力强度因子的影响。以上研究为带裂纹功能梯度厚壁圆筒的可靠性分析及结构优化设计提供了参考。

关键词：功能梯度材料厚壁圆筒热冲击温度应力强度因子有限元分析裂纹

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基于图像处理的植物叶片参数的测量

东北林业大学学报 2009年第4期37卷 46-47,53页

作者：陈爱军东北林业大学哈尔滨150040

针对传统植物叶片参数手工测量方法精度低、速度慢的缺点,提出了一种基于扫描仪和参考物利用图像处理技术来测量植物叶片参数的方法。首先利用扫描仪获得含有植物叶片和参考物的数字图像,然后通过图像处理技术分别获得参考物和被测叶片... 详细信息

针对传统植物叶片参数手工测量方法精度低、速度慢的缺点,提出了一种基于扫描仪和参考物利用图像处理技术来测量植物叶片参数的方法。首先利用扫描仪获得含有植物叶片和参考物的数字图像,然后通过图像处理技术分别获得参考物和被测叶片的二值图像,最后利用实物参考物周长和参考物在图像中周长之间的比例关系来求取被测植物叶片参数。对真实图像进行了实验,结果表明此方法具有较高的效率和实用性。

关键词：植物叶片参数测量参考物扫描仪图像处理

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自紧身管临界裂纹尺寸的概率断裂力学研究

应用力学学报 2005年第1期22卷 36-39页

作者：陈爱军查子初南京理工大学南京210094

基于概率断裂力学理论和MonteCarlo模拟方法,本文进行了自紧身管临界裂纹尺寸的可靠性研究。自紧身管内表面的疲劳裂纹考虑为半椭圆形式。裂纹尖端处的应力强度因子由内压和自紧残余应力共同产生。自紧残余应力采用了符合身管材料具有... 详细信息

基于概率断裂力学理论和MonteCarlo模拟方法,本文进行了自紧身管临界裂纹尺寸的可靠性研究。自紧身管内表面的疲劳裂纹考虑为半椭圆形式。裂纹尖端处的应力强度因子由内压和自紧残余应力共同产生。自紧残余应力采用了符合身管材料具有强化和包辛格效应性能推导的公式计算,它产生的应力强度因子通过权函数方法得到。根据断裂准则,可计算出自紧身管的临界裂纹尺寸。实例分析表明,对数正态分布为临界裂纹尺寸的最佳分布,同时给出了在各种置信度和可靠度下自紧身管的临界裂纹尺寸。

关键词：临界裂纹尺寸概率断裂力学自紧身管 Monte Carlo模拟可靠性

湖南邵阳地区高液限红黏土干缩裂隙演化过程的量化分析

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农业工程学报 2021年第20期37卷 146-153页

作者：陈爱军陈俊桦程峰吴迪桂林电子科技大学建筑与交通工程学院桂林541004

红黏土对环境湿度变化非常敏感,在干燥环境中极易开裂,纵横交错的裂缝网络损害了土壤结构的完整性,很容易诱发红黏土边坡失稳和崩塌,导致农田水利设施的破坏,甚至加剧整个生态环境的水旱灾害。为探究红黏土裂隙的演化规律,该研究采用自... 详细信息

红黏土对环境湿度变化非常敏感,在干燥环境中极易开裂,纵横交错的裂缝网络损害了土壤结构的完整性,很容易诱发红黏土边坡失稳和崩塌,导致农田水利设施的破坏,甚至加剧整个生态环境的水旱灾害。为探究红黏土裂隙的演化规律,该研究采用自制试验装置和三维应变测量系统开展了自然湿热条件下的红黏土泥浆样干燥试验,通过采集土体水分和土表位移、应变和裂隙的变化,定量分析脱湿过程中土体表面裂隙形态和应变场的演变特征,并进一步探讨水分变化对裂隙形态和应变场的影响。结果表明:1)土样表面干缩裂隙的演化一共经历了6个阶段,后阶段裂隙分割前阶段裂隙围成的区域,且不同阶段裂隙的交叉角接近90º;2)裂隙产生初始,裂隙尖端处拉应变约为0.5%,土表面大部分区域处于受拉状态;随着裂隙进一步发展,裂隙周边土体逐渐由拉应变状态向压应变状态转变;当所有裂隙发育完成,裂隙周边土体处于压应变状态;3)裂隙演化阶段与界限含水率有关,当泥浆土样的含水率接近液限时(67.7%),土体表面裂隙开始发育,裂隙迅速张开和延伸;当土的含水率达到塑限时(28.3%),裂隙发展的速率逐渐变缓;当含水率小于缩限时(18.8%),裂隙变化已经很小,裂隙发育接近完成;4)在裂隙演化过程中,早期裂隙的发展持续时间和裂隙宽度均超过后期裂隙;土表不同位置的位移和应变均不相同,土块中心竖向收缩大于边缘竖向收缩,而土块中心位移及应变均小于土块边缘,研究可为红黏土开裂引发的工程地质灾害的预防及治理提供参考。

关键词：土壤水分裂隙红黏土应变场 DIC