为研究受载煤体中裂缝动态发展演化规律及其形态变化特征,以受载煤岩工业CT扫描系统为实验平台,开展单轴、三轴应力加载条件下煤样变形破坏全过程的工业显微CT扫描试验,得到能反映受载煤样失稳破坏全过程的三维裂隙结构CT扫描信息和应力...为研究受载煤体中裂缝动态发展演化规律及其形态变化特征,以受载煤岩工业CT扫描系统为实验平台,开展单轴、三轴应力加载条件下煤样变形破坏全过程的工业显微CT扫描试验,得到能反映受载煤样失稳破坏全过程的三维裂隙结构CT扫描信息和应力-应变曲线等测试结果,运用VG Studio MAX图像分析软件,对CT扫描数据重建体模型得到的可视数字煤芯进行精准的裂缝提取和裂隙形态的数字化定性定量表征,对比分析了单轴、三轴受载条件下煤体裂隙发育形态的动态变化。研究结果表明:工业CT扫描是研究受载煤岩内部裂纹发育演化过程的有效手段,裂隙体积和裂隙率随应力的变化关系是受载煤样裂隙动态演化过程的直观体现,在煤样受载过程中呈现出缓慢降低-缓慢增加-急剧增加-增速放缓的发展规律;煤体在受载条件下内部裂隙演化经历了初始压密、弹性变形、新裂隙渐增、新生裂隙速增、裂隙扩展贯通和残余变形6个阶段,破坏形式为剪切破坏;煤样在三轴加载和单轴加载下的屈服强度和裂隙演化过程以及破坏后的裂隙形态均有显著差异,说明围压是影响受载煤体失稳破坏过程的重要因素;工业CT扫描图像显示,裂纹发育扩展随应力荷载的增加优先沿着矿物与煤基质的接触面开始起裂。研究结果可为煤炭合理安全高效开采及井下支护提供借鉴。展开更多
Image segmentation is a key and fundamental problem in image processing,computer graphics,and computer vision.Level set based method for image segmentation is used widely for its topology flexibility and proper mathem...Image segmentation is a key and fundamental problem in image processing,computer graphics,and computer vision.Level set based method for image segmentation is used widely for its topology flexibility and proper mathematical formulation.However,poor performance of existing level set models on noisy images and weak boundary limit its application in image segmentation.In this paper,we present a region consistency constraint term to measure the regional consistency on both sides of the boundary,this term defines the boundary of the image within a range,and hence increases the stability of the level set model.The term can make existing level set models significantly improve the efficiency of the algorithms on segmenting images with noise and weak boundary.Furthermore,this constraint term can make edge-based level set model overcome the defect of sensitivity to the initial contour.The experimental results show that our algorithm is efficient for image segmentation and outperform the existing state-of-art methods regarding images with noise and weak boundary.展开更多
文摘为研究受载煤体中裂缝动态发展演化规律及其形态变化特征,以受载煤岩工业CT扫描系统为实验平台,开展单轴、三轴应力加载条件下煤样变形破坏全过程的工业显微CT扫描试验,得到能反映受载煤样失稳破坏全过程的三维裂隙结构CT扫描信息和应力-应变曲线等测试结果,运用VG Studio MAX图像分析软件,对CT扫描数据重建体模型得到的可视数字煤芯进行精准的裂缝提取和裂隙形态的数字化定性定量表征,对比分析了单轴、三轴受载条件下煤体裂隙发育形态的动态变化。研究结果表明:工业CT扫描是研究受载煤岩内部裂纹发育演化过程的有效手段,裂隙体积和裂隙率随应力的变化关系是受载煤样裂隙动态演化过程的直观体现,在煤样受载过程中呈现出缓慢降低-缓慢增加-急剧增加-增速放缓的发展规律;煤体在受载条件下内部裂隙演化经历了初始压密、弹性变形、新裂隙渐增、新生裂隙速增、裂隙扩展贯通和残余变形6个阶段,破坏形式为剪切破坏;煤样在三轴加载和单轴加载下的屈服强度和裂隙演化过程以及破坏后的裂隙形态均有显著差异,说明围压是影响受载煤体失稳破坏过程的重要因素;工业CT扫描图像显示,裂纹发育扩展随应力荷载的增加优先沿着矿物与煤基质的接触面开始起裂。研究结果可为煤炭合理安全高效开采及井下支护提供借鉴。
基金supported in part by the NSFC-Zhejiang Joint Fund of the Integration of Informatization and Industrialization(U1609218)NSFC(61772312,61373078,61772253)+1 种基金the Key Research and Development Project of Shandong Province(2017GGX10110)NSF of Shandong Province(ZR2016FM21,ZR2016FM13)
文摘Image segmentation is a key and fundamental problem in image processing,computer graphics,and computer vision.Level set based method for image segmentation is used widely for its topology flexibility and proper mathematical formulation.However,poor performance of existing level set models on noisy images and weak boundary limit its application in image segmentation.In this paper,we present a region consistency constraint term to measure the regional consistency on both sides of the boundary,this term defines the boundary of the image within a range,and hence increases the stability of the level set model.The term can make existing level set models significantly improve the efficiency of the algorithms on segmenting images with noise and weak boundary.Furthermore,this constraint term can make edge-based level set model overcome the defect of sensitivity to the initial contour.The experimental results show that our algorithm is efficient for image segmentation and outperform the existing state-of-art methods regarding images with noise and weak boundary.
