In current research,a series of triaxial tests,which were employed to simulate three typical mining layouts(i.e.,top-coal caving,non-pillar mining and protected coal seam mining),were conducted on coal by using MTS815...In current research,a series of triaxial tests,which were employed to simulate three typical mining layouts(i.e.,top-coal caving,non-pillar mining and protected coal seam mining),were conducted on coal by using MTS815 Flex Test GT rock mechanics test system,and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruction techniques.This work aimed at providing a detail description on the micro-structure and fractureconnectivity characteristics of rupture coal samples under different mining layouts.The results show that:(i)for protected coal seam mining layout,the coal specimens failure is in a compression-shear manner and oppositely,(ii)the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts.By investigating the connectivity features of the generated fractures in the direction ofσ_1,under different mining layouts,it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.展开更多
The material flow in friction stir welded 2014 Al alloy has been investigated using a marker insert technique (MIT). Results of the flow visualization show that the material flow is asymmetrical during the friction ...The material flow in friction stir welded 2014 Al alloy has been investigated using a marker insert technique (MIT). Results of the flow visualization show that the material flow is asymmetrical during the friction stir welding (FSW) process and there are also significant differences in the flow patterns observed on advancing side and retreating side. On advancing side, some material transport forward and some move backward, but on retreating side, material only transport backward. At the top surface of the weld, significant material transport forward due to the action of the rotating tool shoulder. Combining the data from all the markers, a three-dituensional flow visualization, similar to the 3D image reconstruction technique, was obtained. The three-dimensional plot gives the tendency chart of material flow in friction stir welding process and from the plot it can be seen that there is a vertical, circular motion around the longitudinal axis of the weld. On the advancing side of the weld, the material is pushed downward but on the retreating side, the material is pushed toward the crown of the weld. The net result of the two relative motions in both side of the advancing and the retreating is that a circular motion comes into being. Comparatively, the material flow around the longitudinal axis is a secondary motion.展开更多
There is a steadily growing range of applications that can benefit from facial reconstruction techniques,leading to an increasing demand for reconstruction of high-quality 3D face models.While it is an important expre...There is a steadily growing range of applications that can benefit from facial reconstruction techniques,leading to an increasing demand for reconstruction of high-quality 3D face models.While it is an important expressive part of the human face,the nose has received less attention than other expressive regions in the face reconstruction literature.When applying existing reconstruction methods to facial images,the reconstructed nose models are often inconsistent with the desired shape and expression.In this paper,we propose a coarse-to-fine 3D nose reconstruction and correction pipeline to build a nose model from a single image,where 3D and 2D nose curve correspondences are adaptively updated and refined.We first correct the reconstruction result coarsely using constraints of 3D-2D sparse landmark correspondences,and then heuristically update a dense 3D-2D curve correspondence based on the coarsely corrected result.A final refinement step is performed to correct the shape based on the updated 3D-2D dense curve constraints.Experimental results show the advantages of our method for 3D nose reconstruction over existing methods.展开更多
基金financially supported by the Major State Fundamental Research Project of China(Nos.2011CB201201and2010CB226802)the National Natural Science Foundation of China(No.51204113)the Youth Science and Technology Fund of Sichuan Province(No.2012JQ0031)
文摘In current research,a series of triaxial tests,which were employed to simulate three typical mining layouts(i.e.,top-coal caving,non-pillar mining and protected coal seam mining),were conducted on coal by using MTS815 Flex Test GT rock mechanics test system,and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruction techniques.This work aimed at providing a detail description on the micro-structure and fractureconnectivity characteristics of rupture coal samples under different mining layouts.The results show that:(i)for protected coal seam mining layout,the coal specimens failure is in a compression-shear manner and oppositely,(ii)the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts.By investigating the connectivity features of the generated fractures in the direction ofσ_1,under different mining layouts,it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.
文摘The material flow in friction stir welded 2014 Al alloy has been investigated using a marker insert technique (MIT). Results of the flow visualization show that the material flow is asymmetrical during the friction stir welding (FSW) process and there are also significant differences in the flow patterns observed on advancing side and retreating side. On advancing side, some material transport forward and some move backward, but on retreating side, material only transport backward. At the top surface of the weld, significant material transport forward due to the action of the rotating tool shoulder. Combining the data from all the markers, a three-dituensional flow visualization, similar to the 3D image reconstruction technique, was obtained. The three-dimensional plot gives the tendency chart of material flow in friction stir welding process and from the plot it can be seen that there is a vertical, circular motion around the longitudinal axis of the weld. On the advancing side of the weld, the material is pushed downward but on the retreating side, the material is pushed toward the crown of the weld. The net result of the two relative motions in both side of the advancing and the retreating is that a circular motion comes into being. Comparatively, the material flow around the longitudinal axis is a secondary motion.
基金supported by the National Natural Science Foundation of China(Grant Nos.61972342,61602402,and 61902334)Zhejiang Provincial Basic Public Welfare Research(Grant No.LGG19F020001)+1 种基金Shenzhen Fundamental Research(General Project)(Grant No.JCYJ20190814112007258)the Royal Society(Grant No.IES\R1\180126).
文摘There is a steadily growing range of applications that can benefit from facial reconstruction techniques,leading to an increasing demand for reconstruction of high-quality 3D face models.While it is an important expressive part of the human face,the nose has received less attention than other expressive regions in the face reconstruction literature.When applying existing reconstruction methods to facial images,the reconstructed nose models are often inconsistent with the desired shape and expression.In this paper,we propose a coarse-to-fine 3D nose reconstruction and correction pipeline to build a nose model from a single image,where 3D and 2D nose curve correspondences are adaptively updated and refined.We first correct the reconstruction result coarsely using constraints of 3D-2D sparse landmark correspondences,and then heuristically update a dense 3D-2D curve correspondence based on the coarsely corrected result.A final refinement step is performed to correct the shape based on the updated 3D-2D dense curve constraints.Experimental results show the advantages of our method for 3D nose reconstruction over existing methods.