In order to study the constitutive behavior of concrete in mesoscopic level, a new method is proposed in this paper. This method uses random polygon particles to simulate full grading broken aggregates of concrete. Ba...In order to study the constitutive behavior of concrete in mesoscopic level, a new method is proposed in this paper. This method uses random polygon particles to simulate full grading broken aggregates of concrete. Based on computational geometry, we carry out the automatic generation of the triangle finite element mesh for the model of random polygon particles of concrete. The finite element mesh generated in this paper is also applicable to many other numerical methods.展开更多
The geometry of each worn part is unique, so that a repair has to be tailored to each part individually. To ensure that a high quality repair is carried out, tool paths have to be generated adaptively for the tmique g...The geometry of each worn part is unique, so that a repair has to be tailored to each part individually. To ensure that a high quality repair is carried out, tool paths have to be generated adaptively for the tmique geometry and pose of the part being repaired. A polygonal modelling approach is introduced to rapidly construct a geometric model of the part to be repaired, together with a defect-free model with identical geometry and poise. The two models are compared so that the defects are identified for direct use by the laser cladding, machining and inspection processes.展开更多
The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly comp...The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.展开更多
Polygonal models are popular representations of 3D objects. The use of polygonal models in computational applications often requires a model to properly bound a 3D solid. That is, the polygonal model needs to be close...Polygonal models are popular representations of 3D objects. The use of polygonal models in computational applications often requires a model to properly bound a 3D solid. That is, the polygonal model needs to be closed, manifold, and free of self-intersections. This paper surveys a sizeable literature for repairing models that do not satisfy this criteria, focusing on categorizing them by their methodology and capability. We hope to offer pointers to further readings for researchers and practitioners, and suggestions of promising directions for future research endeavors.展开更多
Two simplification algorithms are proposed for automatic decimation of polygonal models, and for generating their LODs. Each algorithm orders vertices according to their priority values and then removes them iterative...Two simplification algorithms are proposed for automatic decimation of polygonal models, and for generating their LODs. Each algorithm orders vertices according to their priority values and then removes them iteratively. For setting the priority value of each vertex, exploiting normal field of its one-ring neighborhood, we introduce a new measure of geometric fidelity that reflects well the local geometric features of the vertex. After a vertex is selected, using other measures of geometric distortion that are based on normal field deviation and distance measure, it is decided which of the edges incident on the vertex is to be collapsed for removing it. The collapsed edge is substituted with a new vertex whose position is found by minimizing the local quadric error measure. A comparison with the state-of-the-art algorithms reveals that the proposed algorithms are simple to implement, are computationally more efficient, generate LODs with better quality, and preserve salient features even after drastic simplification. The methods are useful for applications such as 3D computer games, virtual reality, where focus is on fast running time, reduced memory overhead, and high quality LODs.展开更多
文摘In order to study the constitutive behavior of concrete in mesoscopic level, a new method is proposed in this paper. This method uses random polygon particles to simulate full grading broken aggregates of concrete. Based on computational geometry, we carry out the automatic generation of the triangle finite element mesh for the model of random polygon particles of concrete. The finite element mesh generated in this paper is also applicable to many other numerical methods.
基金supported by National Natural Science Foundation of China(No. 50675040)Science and Technology R&D Project of Guangdong Province, China (No. 2006A10405005, No. 2007A010300015)Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China.
文摘The geometry of each worn part is unique, so that a repair has to be tailored to each part individually. To ensure that a high quality repair is carried out, tool paths have to be generated adaptively for the tmique geometry and pose of the part being repaired. A polygonal modelling approach is introduced to rapidly construct a geometric model of the part to be repaired, together with a defect-free model with identical geometry and poise. The two models are compared so that the defects are identified for direct use by the laser cladding, machining and inspection processes.
基金Project supported by the National Natural Science Foundation of China(No.10472061)Key Project of Shanghai Municipal Commission of Science and Technology(No.04JC14034)+1 种基金the Doctoral Foundation of Ministry of Education of China(No.20060280015)Shanghai Leading Academic Discipline Project(No.Y0103)
文摘The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.
基金supported in part by NSF of USA under Grant Nos.CCF-0702662 and DBI-0743691.
文摘Polygonal models are popular representations of 3D objects. The use of polygonal models in computational applications often requires a model to properly bound a 3D solid. That is, the polygonal model needs to be closed, manifold, and free of self-intersections. This paper surveys a sizeable literature for repairing models that do not satisfy this criteria, focusing on categorizing them by their methodology and capability. We hope to offer pointers to further readings for researchers and practitioners, and suggestions of promising directions for future research endeavors.
文摘Two simplification algorithms are proposed for automatic decimation of polygonal models, and for generating their LODs. Each algorithm orders vertices according to their priority values and then removes them iteratively. For setting the priority value of each vertex, exploiting normal field of its one-ring neighborhood, we introduce a new measure of geometric fidelity that reflects well the local geometric features of the vertex. After a vertex is selected, using other measures of geometric distortion that are based on normal field deviation and distance measure, it is decided which of the edges incident on the vertex is to be collapsed for removing it. The collapsed edge is substituted with a new vertex whose position is found by minimizing the local quadric error measure. A comparison with the state-of-the-art algorithms reveals that the proposed algorithms are simple to implement, are computationally more efficient, generate LODs with better quality, and preserve salient features even after drastic simplification. The methods are useful for applications such as 3D computer games, virtual reality, where focus is on fast running time, reduced memory overhead, and high quality LODs.