3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be effi...3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.展开更多
With the advanced development of computer-based enabling technologies, many engineering, medical, biology, chemistry, physics and food science etc have developed to the unprecedented levels, which lead to many researc...With the advanced development of computer-based enabling technologies, many engineering, medical, biology, chemistry, physics and food science etc have developed to the unprecedented levels, which lead to many research and development interests in various multi-discipline areas. Among them, biomimetics is one of the most promising and attractive branches of study. Biomimetics is a branch of study that uses biological systems as a model to develop synthetic systems. To learn from nature, one of the fundamental issues is to understand the natural systems such animals, insects, plants and human beings etc. The geometrical characterization and representation of natural systems is an important fundamental work for biomimetics research. 3D modeling plays a key role in the geometrical characterization and representation, especially in computer graphical visualization. This paper firstly presents the typical procedure of 3D modelling methods and then reviews the previous work of 3D geometrical modelling techniques and systems developed for industrial, medical and animation applications. Especially the paper discusses the problems associated with the existing techniques and systems when they are applied to 3D modelling of biological systems. Based upon the discussions, the paper proposes some areas of research interests in 3D modelling of biological systems and for Biomimetics.展开更多
Choroidal osteoma (CO) is a rare, ossifying benign tumor originated in the choroid that typically occurs in otherwise healthy young women (1,2). It is characterized by a yellowish, well demarcated lesion in the juxtap...Choroidal osteoma (CO) is a rare, ossifying benign tumor originated in the choroid that typically occurs in otherwise healthy young women (1,2). It is characterized by a yellowish, well demarcated lesion in the juxtapapillary or macular area. The diagnosis is clinical and can be confirmed with the use of fluorescein or indocyanine angiography, optical coherence tomography, computed tomography or magnetic resonance imaging. Choroidal neovascularization or subretinal fluid, the main causes for vision loss, can be treated with laser therapy, photodynamic therapy or intravitreal antivascular endothelial growth factor therapy. We present a case of choroidal osteoma, showing the role of the high resolution 3D spiral computed tomography.展开更多
Fe-rich intermetallics, especially β-Fe phase, usually forming in the microstructure of cast aluminum alloys, are very detrimental to mechanical properties. In the present work, the effects of Fe content on phase tra...Fe-rich intermetallics, especially β-Fe phase, usually forming in the microstructure of cast aluminum alloys, are very detrimental to mechanical properties. In the present work, the effects of Fe content on phase transformation and microstructures were analyzed using a 3D X-ray microscope. Based on the highresolution 3D X-ray computed tomography, the 3D characteristics of Fe-rich intermetallics and micropores in the gravity-cast Al-6 Si alloys with different Fe contents were investigated. In addition, the effect of intermetallics on the microporosity was discussed. The results show that with increasing the Fe content from 0.10 wt.% to 0.60 wt.%, the volume fraction of Fe-rich intermetallics and the volume of the largest size Fe-rich intermetallic increased, and the 3D morphology of intermetallics changed from fine flake to network aggregation. As the Fe contents increased, the shrinkage pores were characterized, which were rather complex due to the micropores promoted by the intermetallics interactions.展开更多
Several approaches for fast generation of digital holograms of a three-dimensional （3D） object have been discussed. Among them, the novel look-up table （N-LUT） method is analyzed to dramatically reduce the number ...Several approaches for fast generation of digital holograms of a three-dimensional （3D） object have been discussed. Among them, the novel look-up table （N-LUT） method is analyzed to dramatically reduce the number of pre-calculated fringe patterns required for computation of digital holograms of a 3D object by employing a new concept of principal fringe patterns, so that problems of computational complexity and huge memory size of the conventional ray-tracing and look-up table methods have been considerably alleviated. Meanwhile, as the 3D video images have a lot of temporally or spatially redundant data in their inter- and intra-frames, computation time of the 3D video holograms could be also reduced just by removing these redundant data. Thus, a couple of computational methods for generation of 3D video holograms by combined use of the N-LUT method and data compression algorithms are also presented and discussed. Some experimental results finally reveal that by using this approach a great reduction of computation time of 3D video holograms could be achieved.展开更多
Objective To evaluate the significance of multidetector CT 3D reconstruction technique inshowing anatomy of ethmoid sinus, at the same time, anatomic variations of ethmoid sinus and its clinical significance were also...Objective To evaluate the significance of multidetector CT 3D reconstruction technique inshowing anatomy of ethmoid sinus, at the same time, anatomic variations of ethmoid sinus and its clinical significance were also discussed. Methods 250 cases of ethmoid sinuses were scanned transversally by multidetector scaner, coronal and sagittal views were reconstructed. Results Coronal and sagittal views were good enough to make diagnosis. 5 kinds of common ethmoid sinus variations were seen, including pneumatization of ethmoid bulla (56. 5% ) , Onodi air cell(26% ) , Haller cell(6. 5% ) ,low ethmoid foveolas(4. 3% )and over intromigratiny lamella papyracea (6. 5% ). Conclusion The coronal and other special views of ethmoid sinus are showed clearly by 3D reconstruction which can provide detailed image informations for functional endoscopic sinus surgery.展开更多
During the long-term construction and development process of eliminating water disasters and promoting water conservancy in traditional settlements,a set of mature strategies that have simple ecological wisdom in wate...During the long-term construction and development process of eliminating water disasters and promoting water conservancy in traditional settlements,a set of mature strategies that have simple ecological wisdom in water layout have been formed by adapting to the natural water environment and utilizing the regional water system.This study conducted a qualitative and quantitative analysis of the water layout strategies and their effects on Liukeng Village from three aspects:deciphering the water systematic pattern,calculating the spatial characteristics and quantifying the water environment,to explore the technical assistance and potential of water layout research in traditional rural settlements.The results indicated that Liukeng has an unambiguously systematic water layout pattern of source diversion,middle drainage and end purification of the water.Through 3D point cloud computing,it was shown that the site selection made accurate use of micro-topography and adopted the strategy of a multi-source water management.It formed an organic water system pattern,which provided sufficient water sources for all kinds of needs of Liukeng Village.The Dragon Lake in Liukeng held 83.0%of the precipitation,and the vegetation area accounted for 34.7%of the total area of Liukeng,which had high surface permeability and good middle drainage effects.Water detection showed that the Dragon Lake provided good water quality and purification.The purposes of this study are to fill the gap in previous non-quantitative research on water layout in traditional rural settlements,excavate the hidden information and value of settlements,and deepen our understanding of the ecological wisdom of the overall planning,layout and construction of water conservancy in traditional rural settlements.This knowledge can assist the win-win situation of water conservancy cultural heritage protection and modern utilization.It also provides useful inspiration and reference for properly dealing with the problems of rain and flooding,realizing the sustainability of water resources,and protecting the ecological environment in the process of the development and construction of village settlements in China.展开更多
基金supported by NSFC(Nos.41274120,41404085,and 41504084)
文摘3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.
文摘With the advanced development of computer-based enabling technologies, many engineering, medical, biology, chemistry, physics and food science etc have developed to the unprecedented levels, which lead to many research and development interests in various multi-discipline areas. Among them, biomimetics is one of the most promising and attractive branches of study. Biomimetics is a branch of study that uses biological systems as a model to develop synthetic systems. To learn from nature, one of the fundamental issues is to understand the natural systems such animals, insects, plants and human beings etc. The geometrical characterization and representation of natural systems is an important fundamental work for biomimetics research. 3D modeling plays a key role in the geometrical characterization and representation, especially in computer graphical visualization. This paper firstly presents the typical procedure of 3D modelling methods and then reviews the previous work of 3D geometrical modelling techniques and systems developed for industrial, medical and animation applications. Especially the paper discusses the problems associated with the existing techniques and systems when they are applied to 3D modelling of biological systems. Based upon the discussions, the paper proposes some areas of research interests in 3D modelling of biological systems and for Biomimetics.
文摘Choroidal osteoma (CO) is a rare, ossifying benign tumor originated in the choroid that typically occurs in otherwise healthy young women (1,2). It is characterized by a yellowish, well demarcated lesion in the juxtapapillary or macular area. The diagnosis is clinical and can be confirmed with the use of fluorescein or indocyanine angiography, optical coherence tomography, computed tomography or magnetic resonance imaging. Choroidal neovascularization or subretinal fluid, the main causes for vision loss, can be treated with laser therapy, photodynamic therapy or intravitreal antivascular endothelial growth factor therapy. We present a case of choroidal osteoma, showing the role of the high resolution 3D spiral computed tomography.
基金supported by the Industry Base Enhanced Project(TC160A310-10-01)Guangdong Sci&Tech Project(2013A090100002)Guangzhou Sci&Tech Project(2014Y2-00214)
文摘Fe-rich intermetallics, especially β-Fe phase, usually forming in the microstructure of cast aluminum alloys, are very detrimental to mechanical properties. In the present work, the effects of Fe content on phase transformation and microstructures were analyzed using a 3D X-ray microscope. Based on the highresolution 3D X-ray computed tomography, the 3D characteristics of Fe-rich intermetallics and micropores in the gravity-cast Al-6 Si alloys with different Fe contents were investigated. In addition, the effect of intermetallics on the microporosity was discussed. The results show that with increasing the Fe content from 0.10 wt.% to 0.60 wt.%, the volume fraction of Fe-rich intermetallics and the volume of the largest size Fe-rich intermetallic increased, and the 3D morphology of intermetallics changed from fine flake to network aggregation. As the Fe contents increased, the shrinkage pores were characterized, which were rather complex due to the micropores promoted by the intermetallics interactions.
基金supported by the MKE (Ministry of Knowledge Economy), Korea, under the ITRC (Informa-tion Technology Research Center)support program su-pervised by the NIPA (National IT Industry Promotion Agency) (NIPA-2009-C1090-0902-0018)
文摘Several approaches for fast generation of digital holograms of a three-dimensional （3D） object have been discussed. Among them, the novel look-up table （N-LUT） method is analyzed to dramatically reduce the number of pre-calculated fringe patterns required for computation of digital holograms of a 3D object by employing a new concept of principal fringe patterns, so that problems of computational complexity and huge memory size of the conventional ray-tracing and look-up table methods have been considerably alleviated. Meanwhile, as the 3D video images have a lot of temporally or spatially redundant data in their inter- and intra-frames, computation time of the 3D video holograms could be also reduced just by removing these redundant data. Thus, a couple of computational methods for generation of 3D video holograms by combined use of the N-LUT method and data compression algorithms are also presented and discussed. Some experimental results finally reveal that by using this approach a great reduction of computation time of 3D video holograms could be achieved.
文摘Objective To evaluate the significance of multidetector CT 3D reconstruction technique inshowing anatomy of ethmoid sinus, at the same time, anatomic variations of ethmoid sinus and its clinical significance were also discussed. Methods 250 cases of ethmoid sinuses were scanned transversally by multidetector scaner, coronal and sagittal views were reconstructed. Results Coronal and sagittal views were good enough to make diagnosis. 5 kinds of common ethmoid sinus variations were seen, including pneumatization of ethmoid bulla (56. 5% ) , Onodi air cell(26% ) , Haller cell(6. 5% ) ,low ethmoid foveolas(4. 3% )and over intromigratiny lamella papyracea (6. 5% ). Conclusion The coronal and other special views of ethmoid sinus are showed clearly by 3D reconstruction which can provide detailed image informations for functional endoscopic sinus surgery.
基金The National Natural Science Foundation of China(51878439,51878437,51908179)The Project of Key Laboratory of Ministry of Cultureand Tourism(20180508)+1 种基金The Youth Foundation for Humanities and Social Sciences of the Ministry of Education(17YJCZH095)The SocialScience Foundation of Hebei Province(HB19YS036).
文摘During the long-term construction and development process of eliminating water disasters and promoting water conservancy in traditional settlements,a set of mature strategies that have simple ecological wisdom in water layout have been formed by adapting to the natural water environment and utilizing the regional water system.This study conducted a qualitative and quantitative analysis of the water layout strategies and their effects on Liukeng Village from three aspects:deciphering the water systematic pattern,calculating the spatial characteristics and quantifying the water environment,to explore the technical assistance and potential of water layout research in traditional rural settlements.The results indicated that Liukeng has an unambiguously systematic water layout pattern of source diversion,middle drainage and end purification of the water.Through 3D point cloud computing,it was shown that the site selection made accurate use of micro-topography and adopted the strategy of a multi-source water management.It formed an organic water system pattern,which provided sufficient water sources for all kinds of needs of Liukeng Village.The Dragon Lake in Liukeng held 83.0%of the precipitation,and the vegetation area accounted for 34.7%of the total area of Liukeng,which had high surface permeability and good middle drainage effects.Water detection showed that the Dragon Lake provided good water quality and purification.The purposes of this study are to fill the gap in previous non-quantitative research on water layout in traditional rural settlements,excavate the hidden information and value of settlements,and deepen our understanding of the ecological wisdom of the overall planning,layout and construction of water conservancy in traditional rural settlements.This knowledge can assist the win-win situation of water conservancy cultural heritage protection and modern utilization.It also provides useful inspiration and reference for properly dealing with the problems of rain and flooding,realizing the sustainability of water resources,and protecting the ecological environment in the process of the development and construction of village settlements in China.
