A modified inner-element edge-based smoothed finite element method(IES-FEM)is developed and integrated with ABAQUS using a user-defined element(UEL)in this study.Initially,the smoothing domain discretization of IES-FE...A modified inner-element edge-based smoothed finite element method(IES-FEM)is developed and integrated with ABAQUS using a user-defined element(UEL)in this study.Initially,the smoothing domain discretization of IES-FEM is described and compared with ES-FEM.A practical modification of IES-FEM is then introduced that used the technique employed by ES-FEM for the nodal strain calculation.The differences in the strain computation among ES-FEM,IES-FEM,and FEM are then discussed.The modified IES-FEM exhibited superior performance in displacement and a slight advantage in stress compared to FEM using the same mesh according to the results obtained from both the regular and irregular elements.The robustness of the IES-FEM to severely deformed meshes was also verified.展开更多
The main purpose of this paper is to present numerical results of static bending and free vibration of functionally graded porous(FGP) variable-thickness plates by using an edge-based smoothed finite element method(ES...The main purpose of this paper is to present numerical results of static bending and free vibration of functionally graded porous(FGP) variable-thickness plates by using an edge-based smoothed finite element method(ES-FEM) associate with the mixed interpolation of tensorial components technique for the three-node triangular element(MITC3), so-called ES-MITC3. This ES-MITC3 element is performed to eliminate the shear locking problem and to enhance the accuracy of the existing MITC3 element. In the ES-MITC3 element, the stiffness matrices are obtained by using the strain smoothing technique over the smoothing domains formed by two adjacent MITC3 triangular elements sharing an edge. Materials of the plate are FGP with a power-law index(k) and maximum porosity distributions(U) in the forms of cosine functions. The influences of some geometric parameters, material properties on static bending, and natural frequency of the FGP variable-thickness plates are examined in detail.展开更多
Numerical schemes for the transport equation on unstructured meshes usually exhibit the convergence rate p∈[k,k+1],where k is the order of the truncation error.For the discontinuous Galerkin method,the result p=k+1/2...Numerical schemes for the transport equation on unstructured meshes usually exhibit the convergence rate p∈[k,k+1],where k is the order of the truncation error.For the discontinuous Galerkin method,the result p=k+1/2 is known,and the example where the convergence rate is exactly k+1/2 was constructed by Peterson(SIAM J.Numer.Anal.28:133–140,1991)for k=0 and k=1.For finite-volume methods with k≥1,there are no theoretical results for general meshes.In this paper,we consider three edge-based finite-volume schemes with k=1,namely the Barth scheme,the Luo scheme,and the EBR3.For a special family of meshes,under stability assumption we prove the convergence rate p=3/2 for the Barth scheme and p=5/4 for the other ones.We also present a Peterson-type example showing that the values 3/2 and 5/4 are optimal.展开更多
This paper shows that lumped directed-area vectors at edges and dual volumes required to implement the edge-based discretization can be computed without explicitly forming the dual control volume around each node for ...This paper shows that lumped directed-area vectors at edges and dual volumes required to implement the edge-based discretization can be computed without explicitly forming the dual control volume around each node for triangular and tetrahedral grids.It is a simpler implementation because there is no need to form a dual control volume by connecting edge-midpoints,face centroids,and element centroids,and it also reduces the time for computing lumped directed-area vectors for a given grid,especially for tetrahedral grids.The speed-up achieved by the proposed algorithm may not be large enough to greatly impact the overall simulation time,but the proposed algorithm is expected to serve as a major stepping stone towards extending the edge-based discretization to four dimensions and beyond(e.g.,space-time simulation s).Efficient algorithms for computing lumped directed-a rea vectors and dual volumes without forming dual control volumes are presented,and their implementations are described and compared with traditional algorithms in terms of complexity as well as actual computing time for a given grid.展开更多
Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is a major cause of cancer-related deaths in Asia and Africa. Developing effective and non-invasive biomarkers of HCC for individual patients remains an u...Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is a major cause of cancer-related deaths in Asia and Africa. Developing effective and non-invasive biomarkers of HCC for individual patients remains an urgent task for early diagnosis and convenient monitoring. Analyzing the transcriptomic profiles of peripheral blood mononuclear cells from both healthy donors and patients with chronic HBV infection in different states (i.e. HBV carrier, chronic hepatitis B, cirrhosis, and HCC), we identified a set of 19 candidate genes according to our algorithm of dynamic network biomarkers. These genes can both characterize different stages during HCC progression and identify cirrhosis as the critical transition stage before carcinogenesis. The interaction effects (i.e. coexpressions) of candidate genes were used to build an accurate prediction model: the so-called edge-based biomarker. Considering the convenience and robustness of biomarkers in clinical applications, we performed functional analysis, validated candidate genes in other independent samples of our collected cohort, and finally selected COL5A1, HLA-DQB1, MMP2, and CDK4 to build edge panel as prediction models. We demonstrated that the edge panel had great performance in both diagnosis and prognosis in terms of precision and specificity for HCC, especially for patients with alpha-fetoprotein-negative HCC. Our study not only provides a novel edge-based biomarker for non-invasive and effective diagnosis of HBV-associated HCC to each individual patient but also introduces a new way to integrate the interaction terms of individual molecules for clinical diagnosis and prognosis from the network and dynamics perspectives.展开更多
The finite volume(FV)method is the dominating discretization technique for computational fluid dynamics(CFD),particularly in the case of compressible fluids.The discontinuous Galerkin(DG)method has emerged as a promis...The finite volume(FV)method is the dominating discretization technique for computational fluid dynamics(CFD),particularly in the case of compressible fluids.The discontinuous Galerkin(DG)method has emerged as a promising highaccuracy alternative.The standard DG method reduces to a cell-centered FV method at lowest order.However,many of today’s CFD codes use a vertex-centered FV method in which the data structures are edge based.We develop a new DG method that reduces to the vertex-centered FV method at lowest order,and examine here the new scheme for scalar hyperbolic problems.Numerically,the method shows optimal-order accuracy for a smooth linear problem.By applying a basic hp-adaption strategy,the method successfully handles shocks.We also discuss how to extend the FV edge-based data structure to support the new scheme.In this way,it will in principle be possible to extend an existing code employing the vertex-centered and edge-based FV discretization to encompass higher accuracy through the new DG method.展开更多
For a pair of nodes s, t in an undirected graph G = (V, A) and a given level U of allowable delay, we would like to modify the network by node-based or edge-based upgrading strategies to make the delay between s and t...For a pair of nodes s, t in an undirected graph G = (V, A) and a given level U of allowable delay, we would like to modify the network by node-based or edge-based upgrading strategies to make the delay between s and t not greater than U. In this paper, we present some NP-hard results for the delay improvement problems.展开更多
Three-dimensional forward modeling magnetotellurics （MT） problems. We present a is a challenge for geometrically complex new edge-based finite-element algorithm using an unstructured mesh for accurately and efficien...Three-dimensional forward modeling magnetotellurics （MT） problems. We present a is a challenge for geometrically complex new edge-based finite-element algorithm using an unstructured mesh for accurately and efficiently simulating 3D MT responses. The electric field curl-curl equation in the frequency domain was used to deduce the H （curl） variation weak form of the MT forward problem, the Galerkin rule was used to derive a linear finite-element equation on the linear-edge tetrahedroid space, and, finally, a BI-CGSTAB solver was used to estimate the unknown electric fields. A local mesh refinement technique in the neighbor of the measuring MT stations was used to greatly improve the accuracies of the numerical solutions. Four synthetic models validated the powerful performance of our algorithms. We believe that our method will effectively contribute to processing more complex MT studies.展开更多
In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteri...In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteristics of SBTEM responses for complex geoelectrical models.To solve the double-curl diff usion equation for the electric fi eld,we use an unstructured tetrahedral mesh to discretize the model domain and select the unconditionally stable backward Euler scheme to discretize the time derivative.In our numerical experiments,we use a grounded wire as a transmitting source.After validating the algorithm’s eff ectiveness,we first analyze the diffusion characteristics and detectability of the electromagnetic field.After that,we focus our attention on the distribution and the cause of zero bands for Ex and dBy/dt components with the hope of guiding future field surveys.Finally,by simulating diff erent models,we analyze the capability of the SBTEM method in detecting typical mineral veins so that we can provide a reference for mineral resource exploration in the deep earth.展开更多
Fully recognize various problems in the observed magnetotelluric(MT)data is the precondition of inverse solutions.In the paper,according to the geomorphological conditions of the observational MT stations in the Guang...Fully recognize various problems in the observed magnetotelluric(MT)data is the precondition of inverse solutions.In the paper,according to the geomorphological conditions of the observational MT stations in the Guangxi area,we constructed several different kinds of models to conduct a three-dimensional forward simulation of the MT fi eld using the vector fi nite element method(FEM).First,the variation rule and differences of apparent resistivityρxy andρyx in the xy and yx modes were studied and analyzed,and then the geoelectric information refl ected by the change of apparent resistivityρxx andρyy were discussed.Final,the responses of typical geological structures that cause a static shift problem were presented.The synthetic examples showed thatρxy andρyx were relevant to the layout of the survey line,for instance,ρxy had different values along the west-east profi le compared with that of the southnorth profi le,Moreover,ρxx andρyy could subtly show the abnormal body-host rock interface,which could be used to restrict the anomalous domain in the inversion process.In addition to the scale and depth of the top surface of the anomalous body,the widespread rivers and hills,can simulate static shift.Hence,to reduce the infl uence of static shift on MT data,a reasonable distance between a station and rivers or hills should be considered in accordance with the scale of rivers or hills.展开更多
Recently,so-called tree-based phylogenetic networks have attracted considerable attention.These networks can be constructed from a phylogenetic tree,called the base tree,by adding additional edges.The primary aim of t...Recently,so-called tree-based phylogenetic networks have attracted considerable attention.These networks can be constructed from a phylogenetic tree,called the base tree,by adding additional edges.The primary aim of this study is to provide sufficient criteria for tree-basedness by reducing phylogenetic networks to related graph structures.Even though it is generally known that determining whether a network is tree-based is an NP-complete problem,one of these criteria,namely edge-basedness,can be verified in linear time.Surprisingly,the class of edgebased networks is closely related to a well-known family of graphs,namely,the class of generalized series-parallel graphs,and we explore this relationship in full detail.Additionally,we introduce further classes of tree-based networks and analyze their relationships.展开更多
With the development of network science,the coupling between networks has become the focus of complex network research.However,previous studies mainly focused on the coupling between nodes,while ignored the coupling b...With the development of network science,the coupling between networks has become the focus of complex network research.However,previous studies mainly focused on the coupling between nodes,while ignored the coupling between edges.We propose a novel cascading failure model of two-layer networks.The model considers the different loads and capacities of edges,as well as the elastic and coupling relationship between edges.In addition,a more flexible load-capacity strategy is adopted to verify the model.The simulation results show that the model is feasible.Different networks have different behaviors for the same parameters.By changing the load parameters,capacity parameters,overload parameters,and distribution parameters reasonably,the robustness of the model can be significantly improved.展开更多
An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for des...An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for describing and recognizing categories, for automatic building extraction and for finding the mutual regions in image matching. The method includes directional filtering and searching for straight edge segments in every direction and scale, taking into account edge gradient signs. Line segments are ordered with respect to their orientation and average gradients in the region in question. These segments are used for the construction of an object descriptor. A hierarchical set of feature descriptors is developed, taking into consideration the proposed straight line segment detector. Comparative performance is evaluated on the noisy model and in real aerial and satellite imagery.展开更多
This paper presents a corner-based image alignment algorithm based on the procedures of corner-based template matching and geometric parameter estimation. This algorithm consists of two stages: 1) training phase, and ...This paper presents a corner-based image alignment algorithm based on the procedures of corner-based template matching and geometric parameter estimation. This algorithm consists of two stages: 1) training phase, and 2) matching phase. In the training phase, a corner detection algorithm is used to extract the corners. These corners are then used to build the pyramid images. In the matching phase, the corners are obtained using the same corner detection algorithm. The similarity measure is then determined by the differences of gradient vector between the corners obtained in the template image and the inspection image, respectively. A parabolic function is further applied to evaluate the geometric relationship between the template and the inspection images. Results show that the corner-based template matching outperforms the original edge-based template matching in efficiency, and both of them are robust against non-liner light changes. The accuracy and precision of the corner-based image alignment are competitive to that of edge-based image alignment under the same environment. In practice, the proposed algorithm demonstrates its precision, efficiency and robustness in image alignment for real world applications.展开更多
The Leontovich impedance boundary condition(IBC)is combined with the edge-based finite element method(FEM)in this paper to analyze the electromagnetic(EM)scattering of cavities coated with a multilayered dielectric.Th...The Leontovich impedance boundary condition(IBC)is combined with the edge-based finite element method(FEM)in this paper to analyze the electromagnetic(EM)scattering of cavities coated with a multilayered dielectric.The IBC on the surface of the medium and the boundary integral equation on the aperture of the cavity are transformed into the third boundary condition,and then the functional of the boundary value problem is obtained.The surface impedance of the layered dielectric is calculated by the generalized reflection coefficient;hence,the multireflection of the EM wave in the dielectric is involved.As a result,the IBC is improved.Numerical results are presented,which demonstrate that the presented IBC/FEM approach is accurate and convenient for the analysis of EM scattering of open-ended cavities coated with the dielectric.展开更多
基金the National Natural Science Foundation of China(No.11672238)the 111 Project(No.BP0719007)the Shaanxi Province Natural Science Foundation(No.2020JZ-06)for the financial support.
文摘A modified inner-element edge-based smoothed finite element method(IES-FEM)is developed and integrated with ABAQUS using a user-defined element(UEL)in this study.Initially,the smoothing domain discretization of IES-FEM is described and compared with ES-FEM.A practical modification of IES-FEM is then introduced that used the technique employed by ES-FEM for the nodal strain calculation.The differences in the strain computation among ES-FEM,IES-FEM,and FEM are then discussed.The modified IES-FEM exhibited superior performance in displacement and a slight advantage in stress compared to FEM using the same mesh according to the results obtained from both the regular and irregular elements.The robustness of the IES-FEM to severely deformed meshes was also verified.
基金funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant number 107.02-2019.330。
文摘The main purpose of this paper is to present numerical results of static bending and free vibration of functionally graded porous(FGP) variable-thickness plates by using an edge-based smoothed finite element method(ES-FEM) associate with the mixed interpolation of tensorial components technique for the three-node triangular element(MITC3), so-called ES-MITC3. This ES-MITC3 element is performed to eliminate the shear locking problem and to enhance the accuracy of the existing MITC3 element. In the ES-MITC3 element, the stiffness matrices are obtained by using the strain smoothing technique over the smoothing domains formed by two adjacent MITC3 triangular elements sharing an edge. Materials of the plate are FGP with a power-law index(k) and maximum porosity distributions(U) in the forms of cosine functions. The influences of some geometric parameters, material properties on static bending, and natural frequency of the FGP variable-thickness plates are examined in detail.
基金supported by the Russian Science Foundation,project 22-11-00199.
文摘Numerical schemes for the transport equation on unstructured meshes usually exhibit the convergence rate p∈[k,k+1],where k is the order of the truncation error.For the discontinuous Galerkin method,the result p=k+1/2 is known,and the example where the convergence rate is exactly k+1/2 was constructed by Peterson(SIAM J.Numer.Anal.28:133–140,1991)for k=0 and k=1.For finite-volume methods with k≥1,there are no theoretical results for general meshes.In this paper,we consider three edge-based finite-volume schemes with k=1,namely the Barth scheme,the Luo scheme,and the EBR3.For a special family of meshes,under stability assumption we prove the convergence rate p=3/2 for the Barth scheme and p=5/4 for the other ones.We also present a Peterson-type example showing that the values 3/2 and 5/4 are optimal.
基金funded by the U.S.Army Research Office under the contract/grant number W911 NF-19-1-0429。
文摘This paper shows that lumped directed-area vectors at edges and dual volumes required to implement the edge-based discretization can be computed without explicitly forming the dual control volume around each node for triangular and tetrahedral grids.It is a simpler implementation because there is no need to form a dual control volume by connecting edge-midpoints,face centroids,and element centroids,and it also reduces the time for computing lumped directed-area vectors for a given grid,especially for tetrahedral grids.The speed-up achieved by the proposed algorithm may not be large enough to greatly impact the overall simulation time,but the proposed algorithm is expected to serve as a major stepping stone towards extending the edge-based discretization to four dimensions and beyond(e.g.,space-time simulation s).Efficient algorithms for computing lumped directed-a rea vectors and dual volumes without forming dual control volumes are presented,and their implementations are described and compared with traditional algorithms in terms of complexity as well as actual computing time for a given grid.
基金This research was supported by the National Key Research and Development Program of China (2O17YFAO5O55OO)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB13040700)+4 种基金the Major Program ofthe National Natural Science Foundation of China (81330084)the National Natural Science Foundation of China (8150347 81473443,and 31771476)the National Science and Technology Major Project of China (2012ZX10005001-004)the 'Yang Fan' Program of Sha nghai Committee ofScience and Technology Fund Annotation (14YF1411400 and 18YF1420700)E-lnstitutes of Shanghai Municipal Education Commission (E03008).
文摘Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is a major cause of cancer-related deaths in Asia and Africa. Developing effective and non-invasive biomarkers of HCC for individual patients remains an urgent task for early diagnosis and convenient monitoring. Analyzing the transcriptomic profiles of peripheral blood mononuclear cells from both healthy donors and patients with chronic HBV infection in different states (i.e. HBV carrier, chronic hepatitis B, cirrhosis, and HCC), we identified a set of 19 candidate genes according to our algorithm of dynamic network biomarkers. These genes can both characterize different stages during HCC progression and identify cirrhosis as the critical transition stage before carcinogenesis. The interaction effects (i.e. coexpressions) of candidate genes were used to build an accurate prediction model: the so-called edge-based biomarker. Considering the convenience and robustness of biomarkers in clinical applications, we performed functional analysis, validated candidate genes in other independent samples of our collected cohort, and finally selected COL5A1, HLA-DQB1, MMP2, and CDK4 to build edge panel as prediction models. We demonstrated that the edge panel had great performance in both diagnosis and prognosis in terms of precision and specificity for HCC, especially for patients with alpha-fetoprotein-negative HCC. Our study not only provides a novel edge-based biomarker for non-invasive and effective diagnosis of HBV-associated HCC to each individual patient but also introduces a new way to integrate the interaction terms of individual molecules for clinical diagnosis and prognosis from the network and dynamics perspectives.
基金The authors were supported in part by the ADIGMA project[3]and the Graduate School in Mathematics and Computing,FMB[16].
文摘The finite volume(FV)method is the dominating discretization technique for computational fluid dynamics(CFD),particularly in the case of compressible fluids.The discontinuous Galerkin(DG)method has emerged as a promising highaccuracy alternative.The standard DG method reduces to a cell-centered FV method at lowest order.However,many of today’s CFD codes use a vertex-centered FV method in which the data structures are edge based.We develop a new DG method that reduces to the vertex-centered FV method at lowest order,and examine here the new scheme for scalar hyperbolic problems.Numerically,the method shows optimal-order accuracy for a smooth linear problem.By applying a basic hp-adaption strategy,the method successfully handles shocks.We also discuss how to extend the FV edge-based data structure to support the new scheme.In this way,it will in principle be possible to extend an existing code employing the vertex-centered and edge-based FV discretization to encompass higher accuracy through the new DG method.
文摘For a pair of nodes s, t in an undirected graph G = (V, A) and a given level U of allowable delay, we would like to modify the network by node-based or edge-based upgrading strategies to make the delay between s and t not greater than U. In this paper, we present some NP-hard results for the delay improvement problems.
基金National High Technology Research and Development Program(863 Program)(No.2006AA06Z105,2007AA06Z134)
文摘Three-dimensional forward modeling magnetotellurics （MT） problems. We present a is a challenge for geometrically complex new edge-based finite-element algorithm using an unstructured mesh for accurately and efficiently simulating 3D MT responses. The electric field curl-curl equation in the frequency domain was used to deduce the H （curl） variation weak form of the MT forward problem, the Galerkin rule was used to derive a linear finite-element equation on the linear-edge tetrahedroid space, and, finally, a BI-CGSTAB solver was used to estimate the unknown electric fields. A local mesh refinement technique in the neighbor of the measuring MT stations was used to greatly improve the accuracies of the numerical solutions. Four synthetic models validated the powerful performance of our algorithms. We believe that our method will effectively contribute to processing more complex MT studies.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos..42030806,41774125,41804098,41904104)the Key National Research Project of China(Grant No.2018YFC0603300).
文摘In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteristics of SBTEM responses for complex geoelectrical models.To solve the double-curl diff usion equation for the electric fi eld,we use an unstructured tetrahedral mesh to discretize the model domain and select the unconditionally stable backward Euler scheme to discretize the time derivative.In our numerical experiments,we use a grounded wire as a transmitting source.After validating the algorithm’s eff ectiveness,we first analyze the diffusion characteristics and detectability of the electromagnetic field.After that,we focus our attention on the distribution and the cause of zero bands for Ex and dBy/dt components with the hope of guiding future field surveys.Finally,by simulating diff erent models,we analyze the capability of the SBTEM method in detecting typical mineral veins so that we can provide a reference for mineral resource exploration in the deep earth.
基金This paper was partially supported by the National Natural Science Foundation of China(No.41674075 and 41904123)the Natural Science Foundation of Guangxi Province(No.2016GXNSFGA380004)and the High Level Innovative Team and Excellent Scholar Plan of Guangxi High Education Institution.
文摘Fully recognize various problems in the observed magnetotelluric(MT)data is the precondition of inverse solutions.In the paper,according to the geomorphological conditions of the observational MT stations in the Guangxi area,we constructed several different kinds of models to conduct a three-dimensional forward simulation of the MT fi eld using the vector fi nite element method(FEM).First,the variation rule and differences of apparent resistivityρxy andρyx in the xy and yx modes were studied and analyzed,and then the geoelectric information refl ected by the change of apparent resistivityρxx andρyy were discussed.Final,the responses of typical geological structures that cause a static shift problem were presented.The synthetic examples showed thatρxy andρyx were relevant to the layout of the survey line,for instance,ρxy had different values along the west-east profi le compared with that of the southnorth profi le,Moreover,ρxx andρyy could subtly show the abnormal body-host rock interface,which could be used to restrict the anomalous domain in the inversion process.In addition to the scale and depth of the top surface of the anomalous body,the widespread rivers and hills,can simulate static shift.Hence,to reduce the infl uence of static shift on MT data,a reasonable distance between a station and rivers or hills should be considered in accordance with the scale of rivers or hills.
基金funded by the state Mecklenburg-Western Pomerania by the Landesgraduierten-Studentshipfunded by the University of Greifswald by the Bogislaw-Studentshipfunded by the German Academic Scholarship Foundation by a studentship.
文摘Recently,so-called tree-based phylogenetic networks have attracted considerable attention.These networks can be constructed from a phylogenetic tree,called the base tree,by adding additional edges.The primary aim of this study is to provide sufficient criteria for tree-basedness by reducing phylogenetic networks to related graph structures.Even though it is generally known that determining whether a network is tree-based is an NP-complete problem,one of these criteria,namely edge-basedness,can be verified in linear time.Surprisingly,the class of edgebased networks is closely related to a well-known family of graphs,namely,the class of generalized series-parallel graphs,and we explore this relationship in full detail.Additionally,we introduce further classes of tree-based networks and analyze their relationships.
基金the National Natural Science Foundation of China(Grant No.61663030)the Natural Science Foundation of Jiangxi Province,China(Grant No.20142BAB207021)the Innovation Fund Designated for Graduate Students of Jiangxi Province,China(Grant No.YC2021-S680).
文摘With the development of network science,the coupling between networks has become the focus of complex network research.However,previous studies mainly focused on the coupling between nodes,while ignored the coupling between edges.We propose a novel cascading failure model of two-layer networks.The model considers the different loads and capacities of edges,as well as the elastic and coupling relationship between edges.In addition,a more flexible load-capacity strategy is adopted to verify the model.The simulation results show that the model is feasible.Different networks have different behaviors for the same parameters.By changing the load parameters,capacity parameters,overload parameters,and distribution parameters reasonably,the robustness of the model can be significantly improved.
文摘An advanced edge-based method of feature detection and extraction is developed for object description in digital images. It is useful for the comparison of different images of the same scene in aerial imagery, for describing and recognizing categories, for automatic building extraction and for finding the mutual regions in image matching. The method includes directional filtering and searching for straight edge segments in every direction and scale, taking into account edge gradient signs. Line segments are ordered with respect to their orientation and average gradients in the region in question. These segments are used for the construction of an object descriptor. A hierarchical set of feature descriptors is developed, taking into consideration the proposed straight line segment detector. Comparative performance is evaluated on the noisy model and in real aerial and satellite imagery.
文摘This paper presents a corner-based image alignment algorithm based on the procedures of corner-based template matching and geometric parameter estimation. This algorithm consists of two stages: 1) training phase, and 2) matching phase. In the training phase, a corner detection algorithm is used to extract the corners. These corners are then used to build the pyramid images. In the matching phase, the corners are obtained using the same corner detection algorithm. The similarity measure is then determined by the differences of gradient vector between the corners obtained in the template image and the inspection image, respectively. A parabolic function is further applied to evaluate the geometric relationship between the template and the inspection images. Results show that the corner-based template matching outperforms the original edge-based template matching in efficiency, and both of them are robust against non-liner light changes. The accuracy and precision of the corner-based image alignment are competitive to that of edge-based image alignment under the same environment. In practice, the proposed algorithm demonstrates its precision, efficiency and robustness in image alignment for real world applications.
文摘The Leontovich impedance boundary condition(IBC)is combined with the edge-based finite element method(FEM)in this paper to analyze the electromagnetic(EM)scattering of cavities coated with a multilayered dielectric.The IBC on the surface of the medium and the boundary integral equation on the aperture of the cavity are transformed into the third boundary condition,and then the functional of the boundary value problem is obtained.The surface impedance of the layered dielectric is calculated by the generalized reflection coefficient;hence,the multireflection of the EM wave in the dielectric is involved.As a result,the IBC is improved.Numerical results are presented,which demonstrate that the presented IBC/FEM approach is accurate and convenient for the analysis of EM scattering of open-ended cavities coated with the dielectric.
