A novel method for modeling cellular materials is proposed based on MATLAB image processing and synchrotron X-ray computed tomography scan- ning to obtain an accurate calculation result of aluminum foam based on finit...A novel method for modeling cellular materials is proposed based on MATLAB image processing and synchrotron X-ray computed tomography scan- ning to obtain an accurate calculation result of aluminum foam based on finite element model. The maximum entropy algorithm is employed to obtain the bina- rization image, and the median filtering algorithm is used to reduce the noise after binarization. The external contour and internal pores boundary is extracted by the ＂edge＂ function in MATLAB, and the geometrical model is reconstructed. A two-step mesh algorithm is adopted to mesh the reconstructed geometrical model. Accordingly, the finite element model of aluminum foam is established by the proposed method based on reconstruction geometrical model. The compression behavior of aluminum foam is obtained at 25℃, 100℃, 200℃ by ABAQUS, and good agreements with experiments are achieved by applying the present recon- struction algorithm and modeling method.展开更多
Fast high-precision patient-specific vascular tissue and geometric structure reconstruction is an essential task for vascular tissue engineering and computer-aided minimally invasive vascular disease diagnosis and sur...Fast high-precision patient-specific vascular tissue and geometric structure reconstruction is an essential task for vascular tissue engineering and computer-aided minimally invasive vascular disease diagnosis and surgery.In this paper,we present an effective vascular geometry reconstruction technique by representing a highly complicated geometric structure of a vascular system as an implicit function.By implicit geometric modelling,we are able to reduce the complexity and level of difficulty of this geometric reconstruction task and turn it into a parallel process of reconstructing a set of simple short tubular-like vascular sections,thanks to the easy-blending nature of implicit geometries on combining implicitly modelled geometric forms.The basic idea behind our technique is to consider this extremely difficult task as a process of team exploration of an unknown environment like a cave.Based on this idea,we developed a parallel vascular modelling technique,called Skeleton Marching,for fast vascular geometric reconstruction.With the proposed technique,we first extract the vascular skeleton system from a given volumetric medical image.A set of sub-regions of a volumetric image containing a vascular segment is then identified by marching along the extracted skeleton tree.A localised segmentation method is then applied to each of these sub-image blocks to extract a point cloud from the surface of the short simple blood vessel segment contained in the image block.These small point clouds are then fitted with a set of implicit surfaces in a parallel manner.A high-precision geometric vascular tree is then reconstructed by blending together these simple tubular-shaped implicit surfaces using the shape-preserving blending operations.Experimental results show the time required for reconstructing a vascular system can be greatly reduced by the proposed parallel technique.展开更多
Computer visualization has marvelous effects when it is applied in various fields,especially in architectural design.As an emerging force in the innovation industry,architects and design agencies have already demonstr...Computer visualization has marvelous effects when it is applied in various fields,especially in architectural design.As an emerging force in the innovation industry,architects and design agencies have already demonstrated the value of architectural visual products in actual application projects.Based on the digital image technology,virtual presentation of future scenes simulates architecture design,architectural renderings and multimedia videos.Therefore,it can help design agencies transform the theoretical design concept into a lively and realistic visual which can provide the audience with a clearer understanding of the engineering and construction projects.However,it is challenging for designers to produce satisfactory renderings due to the frequent fault data during rendering.In this paper,we use the 3Ds MAX as the operating platform and we present an algorithm based on the Bayesian network to construct a vector representation of the fault data.On this basis,a case study of 3D Max’application has also been presented.展开更多
The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent det...The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent detection capability associated with the measurement of the energy spectrum,the primary composition of cosmic rays,and so on,an accurate geometrical reconstruction of air-shower events is fundamental.This paper de-scribes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA(Wide Field of view Cherenkov/Fluorescence Telescope Array)detectors.Two approaches,which take full advantage ofthe WFCTA detectors.are investigated.One is the stereo-angular method,which uses the pointing of triggered SiPMs in the shower trajectory,and the other is the stereo-timing method,which uses the triggering time of the fired SiPMs.The results show that both methods have good geometrical resolution:the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.展开更多
A sailing ship can produce significant disturbances on the water surface,but the perturbation generated by a moving submerged source is much smaller due to the physical property of the free surface,as represented by t...A sailing ship can produce significant disturbances on the water surface,but the perturbation generated by a moving submerged source is much smaller due to the physical property of the free surface,as represented by the rigid-lid assumption,with the geometric displacement barely observed or measured.Based on the stereo imaging principle,an experimental system for the three-dimensional measurement of the surface perturbation is built by assembling two charge coupled device(CCD)sensors,to measure the surface waves generated by a small submerged sphere,including the small-scale vertical displacements and the flow field on the water surface.The obtained results are consistent with those obtained by the theoretical analysis,and the measurement accuracy for the vertical displacements is improved by 50%compared to that of the direct optical method based on the image grey levels.Additionally,the present measurement technique can be efficiently and precisely applied to other measurements of small-scale disturbances on a free surface.展开更多
A comparison of theoretical investigation and numerical simulation of a single bubble oscillation is carried out in this paper.The theoretical research is based on solving Rayleigh-Plesset(R-P)equation and Keller-Miks...A comparison of theoretical investigation and numerical simulation of a single bubble oscillation is carried out in this paper.The theoretical research is based on solving Rayleigh-Plesset(R-P)equation and Keller-Miksis(K-M)equation using Runge-Kutta method.The numerical method focuses on the two discrete methods in the volume of fluid(VOF)method,geometric reconstruction(GR)and modified high resolution interface capturing(MHRIC).The results show that the interface captured by MHRIC in the collapse stage is more stable,and the evolution of bubble radius agrees better with the theoretical solution.The R-P equation and K-M equation,which omit the effect of the energy equation,have limitations when the bubble collapses under ultra-high pressure.展开更多
基金supported by the National Natural Science Foundations of China(11202007,11232001,and 91216301)
文摘A novel method for modeling cellular materials is proposed based on MATLAB image processing and synchrotron X-ray computed tomography scan- ning to obtain an accurate calculation result of aluminum foam based on finite element model. The maximum entropy algorithm is employed to obtain the bina- rization image, and the median filtering algorithm is used to reduce the noise after binarization. The external contour and internal pores boundary is extracted by the ＂edge＂ function in MATLAB, and the geometrical model is reconstructed. A two-step mesh algorithm is adopted to mesh the reconstructed geometrical model. Accordingly, the finite element model of aluminum foam is established by the proposed method based on reconstruction geometrical model. The compression behavior of aluminum foam is obtained at 25℃, 100℃, 200℃ by ABAQUS, and good agreements with experiments are achieved by applying the present recon- struction algorithm and modeling method.
基金partly supported by National Natural Science Foundation of China (No. 61502402)the Fundamental Research Funds for the Central Universities (No. 20720180073)
文摘Fast high-precision patient-specific vascular tissue and geometric structure reconstruction is an essential task for vascular tissue engineering and computer-aided minimally invasive vascular disease diagnosis and surgery.In this paper,we present an effective vascular geometry reconstruction technique by representing a highly complicated geometric structure of a vascular system as an implicit function.By implicit geometric modelling,we are able to reduce the complexity and level of difficulty of this geometric reconstruction task and turn it into a parallel process of reconstructing a set of simple short tubular-like vascular sections,thanks to the easy-blending nature of implicit geometries on combining implicitly modelled geometric forms.The basic idea behind our technique is to consider this extremely difficult task as a process of team exploration of an unknown environment like a cave.Based on this idea,we developed a parallel vascular modelling technique,called Skeleton Marching,for fast vascular geometric reconstruction.With the proposed technique,we first extract the vascular skeleton system from a given volumetric medical image.A set of sub-regions of a volumetric image containing a vascular segment is then identified by marching along the extracted skeleton tree.A localised segmentation method is then applied to each of these sub-image blocks to extract a point cloud from the surface of the short simple blood vessel segment contained in the image block.These small point clouds are then fitted with a set of implicit surfaces in a parallel manner.A high-precision geometric vascular tree is then reconstructed by blending together these simple tubular-shaped implicit surfaces using the shape-preserving blending operations.Experimental results show the time required for reconstructing a vascular system can be greatly reduced by the proposed parallel technique.
文摘Computer visualization has marvelous effects when it is applied in various fields,especially in architectural design.As an emerging force in the innovation industry,architects and design agencies have already demonstrated the value of architectural visual products in actual application projects.Based on the digital image technology,virtual presentation of future scenes simulates architecture design,architectural renderings and multimedia videos.Therefore,it can help design agencies transform the theoretical design concept into a lively and realistic visual which can provide the audience with a clearer understanding of the engineering and construction projects.However,it is challenging for designers to produce satisfactory renderings due to the frequent fault data during rendering.In this paper,we use the 3Ds MAX as the operating platform and we present an algorithm based on the Bayesian network to construct a vector representation of the fault data.On this basis,a case study of 3D Max’application has also been presented.
基金National Natural Science Foundation of China(11903005,11563004,11475190)。
文摘The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent detection capability associated with the measurement of the energy spectrum,the primary composition of cosmic rays,and so on,an accurate geometrical reconstruction of air-shower events is fundamental.This paper de-scribes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA(Wide Field of view Cherenkov/Fluorescence Telescope Array)detectors.Two approaches,which take full advantage ofthe WFCTA detectors.are investigated.One is the stereo-angular method,which uses the pointing of triggered SiPMs in the shower trajectory,and the other is the stereo-timing method,which uses the triggering time of the fired SiPMs.The results show that both methods have good geometrical resolution:the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.
基金Project supported by the National Natural Science Foundation of China(Grant No.11472307).
文摘A sailing ship can produce significant disturbances on the water surface,but the perturbation generated by a moving submerged source is much smaller due to the physical property of the free surface,as represented by the rigid-lid assumption,with the geometric displacement barely observed or measured.Based on the stereo imaging principle,an experimental system for the three-dimensional measurement of the surface perturbation is built by assembling two charge coupled device(CCD)sensors,to measure the surface waves generated by a small submerged sphere,including the small-scale vertical displacements and the flow field on the water surface.The obtained results are consistent with those obtained by the theoretical analysis,and the measurement accuracy for the vertical displacements is improved by 50%compared to that of the direct optical method based on the image grey levels.Additionally,the present measurement technique can be efficiently and precisely applied to other measurements of small-scale disturbances on a free surface.
基金Projects supported by the National Project of China(Grant No.6140206040301).
文摘A comparison of theoretical investigation and numerical simulation of a single bubble oscillation is carried out in this paper.The theoretical research is based on solving Rayleigh-Plesset(R-P)equation and Keller-Miksis(K-M)equation using Runge-Kutta method.The numerical method focuses on the two discrete methods in the volume of fluid(VOF)method,geometric reconstruction(GR)and modified high resolution interface capturing(MHRIC).The results show that the interface captured by MHRIC in the collapse stage is more stable,and the evolution of bubble radius agrees better with the theoretical solution.The R-P equation and K-M equation,which omit the effect of the energy equation,have limitations when the bubble collapses under ultra-high pressure.
