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圆形标志及其椭圆构像间中心偏差的确定 被引量:5
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作者 廖祥春 冯文灏 《武汉测绘科技大学学报》 CSCD 1999年第3期235-239,共5页
当目标面与像片平面不平行时,圆形标志的像将为椭圆,椭圆的中心与标志中心的像存在偏差。当标志较大时,此偏差将显著影响求解的精度。揭示了偏差的方向性,导出了求解偏差的方程。
关键词 工业摄影测量 标志中心偏差 图形标志 椭圆构像
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干湿循环下石灰粉煤灰改良膨胀土的双屈服面本构关系 被引量:4
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作者 邓云叶 文畅平 《工程科学与技术》 EI CAS CSCD 北大核心 2021年第2期75-83,共9页
基于椭圆–抛物线弹塑性本构模型,研究了干湿循环条件下石灰粉煤灰改良膨胀土的双屈服面弹塑性应力–应变本构关系。首先,通过一系列三轴固结排水剪切试验,分别得到不同干湿循环次数下石灰粉煤灰改良膨胀土的偏应力q与轴向应变ε_(1)、... 基于椭圆–抛物线弹塑性本构模型,研究了干湿循环条件下石灰粉煤灰改良膨胀土的双屈服面弹塑性应力–应变本构关系。首先,通过一系列三轴固结排水剪切试验,分别得到不同干湿循环次数下石灰粉煤灰改良膨胀土的偏应力q与轴向应变ε_(1)、剪应变ε_(s),以及轴向应变ε_(1)与体应变ε_(v)的试验曲线;然后,根据三轴试验结果拟合本构模型中的各参数与干湿循环次数之间的关系表达式;最后,引入考虑干湿循环次数的因子,建立考虑干湿循环的双屈服面弹塑性本构模型。研究表明:1)干湿循环作用下,偏应力q与轴向应变ε_(1)关系表现为应变硬化,与体应变ε_(v)表现为应变剪缩;q–ε_(1)、q–ε_(s)试验曲线都呈现出近似双曲线特征。2)干湿循环作用下,土体的偏应力q不断减小,体应变ε_(v)不断增大;干湿循环作用显著降低了石灰粉煤灰改良膨胀土体的抗剪切、抗压缩能力。3)体积屈服面、剪切屈服面在p–q平面上分别为椭圆、抛物线。干湿循环作用下,体积屈服面不断向原点靠近,剪切屈服面不断向p轴靠近;前9次干湿循环作用的影响较为显著,之后屈服面的变化趋于稳定。4)通过引入考虑干湿循环次数的因子所建立的双屈服面本构模型,可定量反映干湿循环作用对石灰粉煤灰改良膨胀土应力–应变关系的影响,以及双屈服面演化过程。该双屈服面本构模型的应力–应变预测值与试验值吻合度较高。 展开更多
关键词 石灰粉煤灰改良膨胀土 干湿循环 椭圆–抛物线本模型 双屈服面应力–应变关系
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A method of remote sensing image water segmentation based on adaptive morphological elliptical structuring elements 被引量:1
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作者 WEN Hao-tian WANG Xiao-peng 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2020年第3期236-243,共8页
The use of visible and infrared remote sensing images to calculate the water area is an effective means to grasp the basic situation of water resources,and water segmentation is the premise of statistics.Generally,the... The use of visible and infrared remote sensing images to calculate the water area is an effective means to grasp the basic situation of water resources,and water segmentation is the premise of statistics.Generally,the edge features of the water in the remote sensing images are complex.When the traditional morphology is used for image segmentation,it is easy to change the image edge and affect the accuracy of image segmentation because the fixed structuring elements are used to perform morphological operations on the image.To segment water in the remote sensing image accurately,a remote sensing image water segmentation method based on adaptive morphological elliptical structuring elements is proposed.Firstly,the eigenvalue and eigenvector of the image are estimated by linear structure tensor,and the elliptical structuring elements are constructed by the eigenvalue and eigenvector.Then adaptive morphological operations are defined,combining the close operation to eliminate the influence of dark detail noise on water without overstretching the water edge,so that the water edge can be maintained more accurately.Finally,on this basis,the water area can be segmented by gray slice.The experimental results show that the proposed method has higher segmentation accuracy and the average segmentation error is less than 1.43%. 展开更多
关键词 image processing adaptive morphology elliptical structuring elements remote sensing images water segmentation gray slice
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