Given a graph G and a positive integer d, an L( d, 1) -labeling of G is afunction / that assigns to each vertex of G a non-negative integer such that |f(u)-f (v) | >=d ifd_c(u, v) =1;|f(u)-f(v) | >=1 if d_c(u, v...Given a graph G and a positive integer d, an L( d, 1) -labeling of G is afunction / that assigns to each vertex of G a non-negative integer such that |f(u)-f (v) | >=d ifd_c(u, v) =1;|f(u)-f(v) | >=1 if d_c(u, v) =2. The L(d, 1)-labeling number of G, lambda_d(G) is theminimum range span of labels over all such labelings, which is motivated by the channel assignmentproblem. We consider the question of finding the minimum edge span beta_d( G) of this labeling.Several classes of graphs such as cycles, trees, complete k-partite graphs, chordal graphs includingtriangular lattice and square lattice which are important to a telecommunication problem arestudied, and exact values are given.展开更多
The cellular neural/nonlinear network (CNN) is a powerful tool for image and video signal processing,robotic and biological visions. This paper discusses a general method for designing template of the global connectiv...The cellular neural/nonlinear network (CNN) is a powerful tool for image and video signal processing,robotic and biological visions. This paper discusses a general method for designing template of the global connectivitydetection (GCD) CNN, which provides parameter inequalities for determining parameter intervals for implementing thecorresponding functions. The GCD CNN has stronger ability and faster rate for determining global connectivity in binarypatterns than the GCD CNN proposed by Zarandy. An example for detecting the connectivity in complex patterns isgiven.展开更多
Among complex network models,the hierarchical network model is the one most close to such real networks as world trade web,metabolic network,WWW,actor network,and so on.It has not only the property of power-law degree...Among complex network models,the hierarchical network model is the one most close to such real networks as world trade web,metabolic network,WWW,actor network,and so on.It has not only the property of power-law degree distribution,but also the scaling clustering coefficient property which Barabási-Albert(BA)model does not have.BA model is a model of network growth based on growth and preferential attachment,showing the scale-free degree distribution property.In this paper,we study the evolution of cooperation on a hierarchical network model,adopting the prisoner's dilemma(PD)game and snowdrift game(SG)as metaphors of the interplay between connected nodes.BA model provides a unifying framework for the emergence of cooperation.But interestingly,we found that on hierarchical model,there is no sign of cooperation for PD game,while the fre-quency of cooperation decreases as the common benefit decreases for SG.By comparing the scaling clustering coefficient prop-erties of the hierarchical network model with that of BA model,we found that the former amplifies the effect of hubs.Considering different performances of PD game and SG on complex network,we also found that common benefit leads to cooperation in the evolution.Thus our study may shed light on the emergence of cooperation in both natural and social environments.展开更多
Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of...Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of China.Both soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map scales.Four indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid units.Subjecting to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC pools.Optimal soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map scales.With these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV < 1% was assumed to be a criterion for all four indices.A quadratic curve regression model,namely,y = – 0.80 × 10^(–6)x^2 + 0.0228 x + 0.0211(R^2 = 0.9994,P < 0.05),and a power function model R? = 10.394?^(0.2153)(R^2 = 0.9759,P < 0.05) were revealed,which describe the relationship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km^2) and the ?,with the highest R^2 among different mathematical regressions,respectively.This knowledge may facilitate the grid partitioning of regions during the investigation and simulation of SOC pool dynamics at a certain map scale,and be referenced to other landscape polygon patches' mesh partition.展开更多
The Dirac symbol is used to represent the discrete complex Hopfield neural network model.The signal-to-noise theory and the computer numerical solution are made to analyse the storage capacity of the model.The storage...The Dirac symbol is used to represent the discrete complex Hopfield neural network model.The signal-to-noise theory and the computer numerical solution are made to analyse the storage capacity of the model.The storage capacity ratio of the model equals to that of the Hopfield model.Finally,using the model to recognize the 4-level grey or color patterns is discussed.展开更多
In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning meth...In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods (vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms) in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.展开更多
The article is devoted to the evaluation of fractal properties of routing data in computer large scale networks. Implemented the study of percolation network topological structures of large dimension and made their tr...The article is devoted to the evaluation of fractal properties of routing data in computer large scale networks. Implemented the study of percolation network topological structures of large dimension and made their transformation into fractal macrostructure. An example of calculating the fractal dimension of the data path for the boundary of the phase transition between the states of network connectivity. The dependence of the fractal dimension of the percolation cluster on the size of the square δ-cover and conductivity value network of large dimension. It is shown that for the value of the fractal dimension of the route dc ≈ 1.5, network has a stable dynamics of development and size of clusters are optimized with respect to the current load on the network.展开更多
Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry betw...Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.展开更多
In view of the application importance of resistance network in modern science and technology, this paper presents the basic structure of a three terminals ladder shaped resistance network, for which, to study in- dept...In view of the application importance of resistance network in modern science and technology, this paper presents the basic structure of a three terminals ladder shaped resistance network, for which, to study in- depth the equivalent resistance, carry out network analysis by applying virtual current method and construct a model of two elements three orders differential equation. Based on different marginal conditions, two general adaptive rules for the three-terminal ladder shaped inlet resistance, as well as two ultimate rules for the equiva- lent resistance of three-terminal infinite ladder shaped were given.展开更多
After a long subway tunnel operators will produce cross-sectional deformation. Articles designed vehicle laser ranging device tbr continuous measurement of tunnel wall to test their defomaed state. The paper also desc...After a long subway tunnel operators will produce cross-sectional deformation. Articles designed vehicle laser ranging device tbr continuous measurement of tunnel wall to test their defomaed state. The paper also describes the tunnel cross-section deltbrmation measurement method, contour titting principles and error analysis and networking technology for wireless data transmission methods. The detection system is designed to achieve a tunnel section of the structural safety testing and deformation that may occur timely disaster warning, the safe operation of the subway tunnel to provide effective protection.展开更多
UV absorption spectrum and neural network theory was used for the analysis of blood sugar concentration. Experimental investigation shows that absorption spectrum has the following characteristics in the wave band of ...UV absorption spectrum and neural network theory was used for the analysis of blood sugar concentration. Experimental investigation shows that absorption spectrum has the following characteristics in the wave band of 200-300 nm: (1) The absorption spectrum is of complex shape, there is more absorption peak in UV-band, it shows that there is a complex absorption phenomenon in blood group macromolecules; (2) The curve shapes of absorption spectra are similar to different samples ,the reason is that the spectrum is synthesis of some group macromolecules absorption spectrum; (3) There is a degree of displacement of absorption peak to different samples; (4) There is no significant correlation between absorbance and blood sugar concentration at 278 nm, but random. Based on the wave band of 280 nm to 300 nm, a neural network model was built to determine the blood sugar concentration.展开更多
Abstract In this paper, we apply EQ1^rot nonconforming finite element to approximate Signorini problem. If 5 the exact solution u EQ1^rot, the error estimate of order O(h) about the broken energy norm is obtained f...Abstract In this paper, we apply EQ1^rot nonconforming finite element to approximate Signorini problem. If 5 the exact solution u EQ1^rot, the error estimate of order O(h) about the broken energy norm is obtained for quadrilateral meshes satisfying regularity assumption and bi-section condition. Furthermore, the superconver- gence results of order EQ1^rot are derived for rectangular meshes. Numerical results are presented to confirm the considered theory.展开更多
The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexag...The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexagon have been theoretically calculated and simulated. It was found that hexagonal grid unit has the highest light transmittance limit under the practical lattice parameters and its decrease in light transmittance caused by the increase of line width in printing process is the least. The grid of three different shapes with same theoretical transmittance is fabricated through flexographic printing. The result shows that the actual light transmittance of the printed TCFs is lower than its theoretical value because of the inevitable width increase of printed grid lines, with slight difference between the three shapes. However, it is greatly different in terms of conductivity, leading to variation in the quality factor Q(defined as the ratio of light transmittance to total resistance) which represents the performance of TCFs. The Q of hexagonal grid(6.04) is the highest, which is 21% higher than that of the square grid.展开更多
Immersed boundary method is a crucial method to deal with particle suspension flow.Particle shapes involved in such flow are usually simple geometry,such as sphere and ellipsoid,which can be conveniently represented b...Immersed boundary method is a crucial method to deal with particle suspension flow.Particle shapes involved in such flow are usually simple geometry,such as sphere and ellipsoid,which can be conveniently represented by the triangular surface grid.When the number of particles and resolution of the surface grid increase,calculating the hydrodynamic force on the particle surface through integration can be time-consuming.Hence,the present paper establishes a fast mapping method to evaluate immersed boundary hydrodynamic force.Firstly,the particle surface grid is generated by an initial triangular element grid.Subsequently,the initial surface grid is refined by bisection refinement to the desired resolution.The final step is to find the triangular element index on the particle triangular surface grid,which contains the projective point.Test cases show that the present mapping algorithm has good accuracy and efficiency for calculating hydrodynamic forces of particles.展开更多
Surface remeshing is widely required in modeling, animation, simulation, and many other computer graphics applications. Improving the elements' quality is a challenging task in surface remeshing. Existing methods ...Surface remeshing is widely required in modeling, animation, simulation, and many other computer graphics applications. Improving the elements' quality is a challenging task in surface remeshing. Existing methods often fail to efficiently remove poor-quality elements especially in regions with sharp features. In this paper, we propose and use a robust segmentation method followed by remeshing the segmented mesh. Mesh segmentation is initiated using an existing Live-wire interaction approach and is further refined using local mesh operations. The refined segmented mesh is finally sent to the remeshing pipeline, in which each mesh segment is remeshed independently. An experimental study compares our mesh segmentation method as well as remeshing results with representative existing methods. We demonstrate that the proposed segmentation method is robust and suitable for remeshing.展开更多
We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a...We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a so-called red-green split. Second, the refined mesh is simplified by a clustering algorithm based on centroidal Voronoi tessellations (CVTs). The accuracy and good quality of the output triangular mesh are achieved by combining adaptive subdivision and the CVTs technique. Test results showed the mesh coarsening scheme to be robust and effective. Examples are shown that validate the method.展开更多
文摘Given a graph G and a positive integer d, an L( d, 1) -labeling of G is afunction / that assigns to each vertex of G a non-negative integer such that |f(u)-f (v) | >=d ifd_c(u, v) =1;|f(u)-f(v) | >=1 if d_c(u, v) =2. The L(d, 1)-labeling number of G, lambda_d(G) is theminimum range span of labels over all such labelings, which is motivated by the channel assignmentproblem. We consider the question of finding the minimum edge span beta_d( G) of this labeling.Several classes of graphs such as cycles, trees, complete k-partite graphs, chordal graphs includingtriangular lattice and square lattice which are important to a telecommunication problem arestudied, and exact values are given.
文摘The cellular neural/nonlinear network (CNN) is a powerful tool for image and video signal processing,robotic and biological visions. This paper discusses a general method for designing template of the global connectivitydetection (GCD) CNN, which provides parameter inequalities for determining parameter intervals for implementing thecorresponding functions. The GCD CNN has stronger ability and faster rate for determining global connectivity in binarypatterns than the GCD CNN proposed by Zarandy. An example for detecting the connectivity in complex patterns isgiven.
基金Project supported by the Natural Science Foundation of ZhejiangProvince, China (No. Y105697)the Ningbo Natural ScienceFoundation,China (No. 2005A610004)
文摘Among complex network models,the hierarchical network model is the one most close to such real networks as world trade web,metabolic network,WWW,actor network,and so on.It has not only the property of power-law degree distribution,but also the scaling clustering coefficient property which Barabási-Albert(BA)model does not have.BA model is a model of network growth based on growth and preferential attachment,showing the scale-free degree distribution property.In this paper,we study the evolution of cooperation on a hierarchical network model,adopting the prisoner's dilemma(PD)game and snowdrift game(SG)as metaphors of the interplay between connected nodes.BA model provides a unifying framework for the emergence of cooperation.But interestingly,we found that on hierarchical model,there is no sign of cooperation for PD game,while the fre-quency of cooperation decreases as the common benefit decreases for SG.By comparing the scaling clustering coefficient prop-erties of the hierarchical network model with that of BA model,we found that the former amplifies the effect of hubs.Considering different performances of PD game and SG on complex network,we also found that common benefit leads to cooperation in the evolution.Thus our study may shed light on the emergence of cooperation in both natural and social environments.
基金Under the auspices of Special Project of National Key Research and Development Program(No.2016YFD0200301)National Natural Science Foundation of China(No.41571206)Special Project of National Science and Technology Basic Work(No.2015FY110700-S2)
文摘Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of China.Both soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map scales.Four indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid units.Subjecting to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC pools.Optimal soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map scales.With these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV < 1% was assumed to be a criterion for all four indices.A quadratic curve regression model,namely,y = – 0.80 × 10^(–6)x^2 + 0.0228 x + 0.0211(R^2 = 0.9994,P < 0.05),and a power function model R? = 10.394?^(0.2153)(R^2 = 0.9759,P < 0.05) were revealed,which describe the relationship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km^2) and the ?,with the highest R^2 among different mathematical regressions,respectively.This knowledge may facilitate the grid partitioning of regions during the investigation and simulation of SOC pool dynamics at a certain map scale,and be referenced to other landscape polygon patches' mesh partition.
文摘The Dirac symbol is used to represent the discrete complex Hopfield neural network model.The signal-to-noise theory and the computer numerical solution are made to analyse the storage capacity of the model.The storage capacity ratio of the model equals to that of the Hopfield model.Finally,using the model to recognize the 4-level grey or color patterns is discussed.
基金This research work is supported by the Projects of National Science Foundation of China (Grant No, 40574052 and 40437018) and National Basic Research Program of China (973 Program) (Grant No. 2007CB209603).Acknowledgements We wish to thank Researcher Xu Tao for his advice and comment. We also thank Mrs. Wang Kun for her help in the process of translation.
文摘In view of the relative positioning problem between non-regular quadrilateral grids and regular rectangle grid nodes in the wave front construction method, concrete realization problems with four grid positioning methods (vector cross product judgment, angle sum, intersection-point, and signs comparison algorithms) in wave front construction which are commonly used in computer graphics are compared and analyzed in this paper. Based on the stability analysis of the location method, the calculation examples show that the vector cross product judgment method is faster and more accurate than other methods in the realization of the relative positioning between non-regular quadrilateral grids and regular rectangle grid nodes in wave front construction. It provides precise grid point attribute values for the next steps of migration and demigration.
文摘The article is devoted to the evaluation of fractal properties of routing data in computer large scale networks. Implemented the study of percolation network topological structures of large dimension and made their transformation into fractal macrostructure. An example of calculating the fractal dimension of the data path for the boundary of the phase transition between the states of network connectivity. The dependence of the fractal dimension of the percolation cluster on the size of the square δ-cover and conductivity value network of large dimension. It is shown that for the value of the fractal dimension of the route dc ≈ 1.5, network has a stable dynamics of development and size of clusters are optimized with respect to the current load on the network.
基金supported by the National Natural Science Foundation of China project (Grant Nos. 41201130, 41101361, and 41371183)
文摘Symmetrical relationships between humans and their environment have been referred to as an extension of symmetries in the human geographical system and have drawn great attention. This paper explored the symmetry between physical and human systems through fractal analysis of the road and drainage networks in Wuling mountainous area. We found that both the road and drainage networks reflect weak clustering distributions. The evolution of the road network shared a significant self-organizing composition, while the drainage network showed obvious double fraetal characteristics. The geometric fractal dimension of the road network was larger than that of the drainage network. In addition, when assigned a weight relating to hierarchy or length, neither the road network nor drainage network showed a fractal property. These findings indicated that the fractal evolution of the road network shared certain similarities with fractal distribution of the drainage network. The symmetry between the two systems resulted from an interactive process of destroying symmetry at the lower order and reconstructing symmetry at the higher order. The relationships between the fractal dimensions of the rural-urban road network, the drainage network andthe urban system indicated that the development of this area was to achieve the symmetrical isomorphism of physical-human geographical systems.
基金a project financed by Natural Science Fund of Education Department of Jiangsu Province (02KJB140008)
文摘In view of the application importance of resistance network in modern science and technology, this paper presents the basic structure of a three terminals ladder shaped resistance network, for which, to study in- depth the equivalent resistance, carry out network analysis by applying virtual current method and construct a model of two elements three orders differential equation. Based on different marginal conditions, two general adaptive rules for the three-terminal ladder shaped inlet resistance, as well as two ultimate rules for the equiva- lent resistance of three-terminal infinite ladder shaped were given.
文摘After a long subway tunnel operators will produce cross-sectional deformation. Articles designed vehicle laser ranging device tbr continuous measurement of tunnel wall to test their defomaed state. The paper also describes the tunnel cross-section deltbrmation measurement method, contour titting principles and error analysis and networking technology for wireless data transmission methods. The detection system is designed to achieve a tunnel section of the structural safety testing and deformation that may occur timely disaster warning, the safe operation of the subway tunnel to provide effective protection.
基金This work was supported by the National Natural Science Foundation of China (No. 10172043).
文摘UV absorption spectrum and neural network theory was used for the analysis of blood sugar concentration. Experimental investigation shows that absorption spectrum has the following characteristics in the wave band of 200-300 nm: (1) The absorption spectrum is of complex shape, there is more absorption peak in UV-band, it shows that there is a complex absorption phenomenon in blood group macromolecules; (2) The curve shapes of absorption spectra are similar to different samples ,the reason is that the spectrum is synthesis of some group macromolecules absorption spectrum; (3) There is a degree of displacement of absorption peak to different samples; (4) There is no significant correlation between absorbance and blood sugar concentration at 278 nm, but random. Based on the wave band of 280 nm to 300 nm, a neural network model was built to determine the blood sugar concentration.
基金supported by National Natural Science Foundation of China (Grant Nos.10971203 and 11271340)Research Fund for the Doctoral Program of Higher Education of China (Grant No.20094101110006)
文摘Abstract In this paper, we apply EQ1^rot nonconforming finite element to approximate Signorini problem. If 5 the exact solution u EQ1^rot, the error estimate of order O(h) about the broken energy norm is obtained for quadrilateral meshes satisfying regularity assumption and bi-section condition. Furthermore, the superconver- gence results of order EQ1^rot are derived for rectangular meshes. Numerical results are presented to confirm the considered theory.
基金supported by the Beijing Municipal Commission of Education Foundation for School Innovation Ability Promotion Plan(Grant No.TJSHG201310015016)the Key Project of Beijing Institute of Graphic Communication(Grant No.Ea201501)the Creative Groups of Materials and Technology of Printed Electronics(Grant No.23190113100)
文摘The effect of grid shape on the properties of transparent conductive films(TCFs) is theoretically analyzed and experimentally verified. The light transmittance by three types of grid shapes: triangle, square and hexagon have been theoretically calculated and simulated. It was found that hexagonal grid unit has the highest light transmittance limit under the practical lattice parameters and its decrease in light transmittance caused by the increase of line width in printing process is the least. The grid of three different shapes with same theoretical transmittance is fabricated through flexographic printing. The result shows that the actual light transmittance of the printed TCFs is lower than its theoretical value because of the inevitable width increase of printed grid lines, with slight difference between the three shapes. However, it is greatly different in terms of conductivity, leading to variation in the quality factor Q(defined as the ratio of light transmittance to total resistance) which represents the performance of TCFs. The Q of hexagonal grid(6.04) is the highest, which is 21% higher than that of the square grid.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51636009 and 52006212)Chinese Academy of Sciences(Grant Nos.ZDBS-LY-JSC033 and XDB22040201).
文摘Immersed boundary method is a crucial method to deal with particle suspension flow.Particle shapes involved in such flow are usually simple geometry,such as sphere and ellipsoid,which can be conveniently represented by the triangular surface grid.When the number of particles and resolution of the surface grid increase,calculating the hydrodynamic force on the particle surface through integration can be time-consuming.Hence,the present paper establishes a fast mapping method to evaluate immersed boundary hydrodynamic force.Firstly,the particle surface grid is generated by an initial triangular element grid.Subsequently,the initial surface grid is refined by bisection refinement to the desired resolution.The final step is to find the triangular element index on the particle triangular surface grid,which contains the projective point.Test cases show that the present mapping algorithm has good accuracy and efficiency for calculating hydrodynamic forces of particles.
基金the National Natural Science Foundation of China(Nos.61772523,61372168,61620106003,and 61331018)supported by a Chinese Government Scholarship
文摘Surface remeshing is widely required in modeling, animation, simulation, and many other computer graphics applications. Improving the elements' quality is a challenging task in surface remeshing. Existing methods often fail to efficiently remove poor-quality elements especially in regions with sharp features. In this paper, we propose and use a robust segmentation method followed by remeshing the segmented mesh. Mesh segmentation is initiated using an existing Live-wire interaction approach and is further refined using local mesh operations. The refined segmented mesh is finally sent to the remeshing pipeline, in which each mesh segment is remeshed independently. An experimental study compares our mesh segmentation method as well as remeshing results with representative existing methods. We demonstrate that the proposed segmentation method is robust and suitable for remeshing.
基金supported by the National Natural Science Foundation of China (No. 60773179)the National Basic Research Program (973) of China (No. 2004CB318000)
文摘We present a novel algorithm for adaptive triangular mesh coarsening. The algorithm has two stages. First, the input triangular mesh is refined by iteratively applying the adaptive subdivision operator that performs a so-called red-green split. Second, the refined mesh is simplified by a clustering algorithm based on centroidal Voronoi tessellations (CVTs). The accuracy and good quality of the output triangular mesh are achieved by combining adaptive subdivision and the CVTs technique. Test results showed the mesh coarsening scheme to be robust and effective. Examples are shown that validate the method.