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Search Results: 1 - 10 of 48102 matches for " Ge Xu "
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Discrete Quasi-Einstein Metrics and Combinatorial Curvature Flows in 3-Dimension
Huabin Ge,Xu Xu
Mathematics , 2013,
Abstract: We define Discrete Quasi-Einstein metrics (DQE-metrics) as the critical points of discrete total curvature functional on triangulated 3-manifolds. We study DQE-metrics by introducing some combinatorial curvature flows. We prove that these flows produce solutions which converge to discrete quasi-Einstein metrics when the initial energy is small enough. The proof relies on a careful analysis of discrete dual-Laplacians which we interpret as the Jacobian matrix of the curvature map. As a consequence, combinatorial curvature flow provides an algorithm to compute discrete sphere packing metrics with prescribed curvatures.
2-Dimensional Combinatorial Calabi Flow in Hyperbolic Background Geometry
Huabin Ge,Xu Xu
Mathematics , 2013,
Abstract: For triangulated surfaces locally embedded in the standard hyperbolic space, we introduce combinatorial Calabi flow as the negative gradient flow of combinatorial Calabi energy. We prove that the flow produces solutions which converge to ZCCP-metric (zero curvature circle packing metric) if the initial energy is small enough. Assuming the curvature has a uniform upper bound less than $2\pi$, we prove that combinatorial Calabi flow exists for all time. Moreover, it converges to ZCCP-metric if and only if ZCCP-metric exists.
A Discrete Ricci Flow on Surfaces in Hyperbolic Background Geometry
Huabin Ge,Xu Xu
Mathematics , 2015,
Abstract: In this paper, we generalize our results in \cite{GX3} to triangulated surfaces in hyperbolic background geometry, which means that all triangles can be embedded in the standard hyperbolic space. We introduce a new discrete Gaussian curvature by dividing the classical discrete Gauss curvature by an area element, which could be taken as the area of the hyperbolic disk packed at each vertex. We prove that the corresponding discrete Ricci flow converges if and only if there exists a circle packing metric with zero curvature. We also prove that the flow converges if the initial curvatures are all negative. Note that, this result does not require the existence of zero curvature metric or Thurston's combinatorial-topological condition. We further generalize the definition of combinatorial curvature to any given area element and prove the equivalence between the existence of zero curvature metric and the convergence of the corresponding flow.
$α$-curvatures and $α$-flows on low dimensional triangulated manifolds
Huabin Ge,Xu Xu
Mathematics , 2015,
Abstract: In this paper, we introduce two discrete curvature flows, which are called $\alpha$-flows on two and three dimensional triangulated manifolds. For triangulated surface $M$, we introduce a new normalization of combinatorial Ricci flow (first introduced by Bennett Chow and Feng Luo \cite{CL1}), aiming at evolving $\alpha$ order discrete Gauss curvature to a constant. When $\alpha\chi(M)\leq0$, we prove that the convergence of the flow is equivalent to the existence of constant $\alpha$-curvature metric. We further get a necessary and sufficient combinatorial-topological-metric condition, which is a generalization of Thurston's combinatorial-topological condition, for the existence of constant $\alpha$-curvature metric. For triangulated 3-manifolds, we generalize the combinatorial Yamabe functional and combinatorial Yamabe problem introduced by the authors in \cite{GX2,GX4} to $\alpha$-order. We also study the $\alpha$-order flow carefully, aiming at evolving $\alpha$ order combinatorial scalar curvature, which is a generalization of Cooper and Rivin's combinatorial scalar curvature, to a constant.
A combinatorial Yamabe problem on two and three dimensional manifolds
Huabin Ge,Xu Xu
Mathematics , 2015,
Abstract: In this paper, we introduce a new combinatorial curvature on two and three dimensional triangulated manifolds, which transforms in the same way as that of the smooth scalar curvature under scaling of the metric and could be used to approximate the Gauss curvature on two dimensional manifolds. Then we use the flow method to study the corresponding constant curvature problem, which is called combinatorial Yamabe problem.
Neural Network Approach for Solving Singular Convex Optimization with Bounded Variables  [PDF]
Rendong Ge, Lijun Liu, Yi Xu
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.33036
Abstract:

Although frequently encountered in many practical applications, singular nonlinear optimization has been always recognized as a difficult problem. In the last decades, classical numerical techniques have been proposed to deal with the singular problem. However, the issue of numerical instability and high computational complexity has not found a satisfactory solution so far. In this paper, we consider the singular optimization problem with bounded variables constraint rather than the common unconstraint model. A novel neural network model was proposed for solving the problem of singular convex optimization with bounded variables. Under the assumption of rank one defect, the original difficult problem is transformed into nonsingular constrained optimization problem by enforcing a tensor term. By using the augmented Lagrangian method and the projection technique, it is proven that the proposed continuous model is convergent to the solution of the singular optimization problem. Numerical simulation further confirmed the effectiveness of the proposed neural network approach.

Research and Implementation of the Cloud Platform Based on the B-learning
Xu Chao,Ge Hongmei
Computer and Information Science , 2012, DOI: 10.5539/cis.v5n4p77
Abstract: The paper puts a “cloud” learning platform mode. In order to improve the quality of education and teaching and solve the problems such as single teaching systems, the gap between classroom teaching and online teaching and less interaction between the teacher and students and so on. First, force on the application of cloud computing, cloud learning and cloud platforms, we analysis and compare to characteristics of the traditional learning platform, and propose a method that based on the B-learning thinking for the cloud learning platform. Then we give an instance of practice application and it proves that the establishment of cloud study platform has improved the efficiency of the teachers’ classroom, the students’ independent learning, teacher-student interaction, and so on. It is of great significance for promoting the teaching techniques of innovation
An Application Research on Configuration Software System Platform Based on Component Technology
Chao Xu,Hongmei Ge
Computer and Information Science , 2012, DOI: 10.5539/cis.v5n3p76
Abstract: This paper proposes a component based configuration software platform model that aims to develop the application system meeting different demands and build a high-quality software integration system. The model separates system logic description from system implementation and reinforces logic extensibility and reusability using the configuration idea of industrial controlling automation for reference on the base of traditional software developing method. From the effects of the application for the real projects, we can see that the method can reduce the system implementation cost and reinforce the software credibility with better maneuverability and reusability.
Energy Optimal Interpolation in Quantum Evolution
Xiao Ge,Zhan Xu
Physics , 2008,
Abstract: We introduce the concept of interpolation in quantum evolution and present a general framework to find the energy optimal Hamiltonian for a quantum system evolving among a given set of middle states using variational and geometric methods. A few special cases are carefully studied. The quantum brachistochrone problem is proved as a special case.
The Sufficiency Principle for Decentralized Data Reduction
Ge Xu,Biao Chen
Mathematics , 2012,
Abstract: This paper develops the sufficiency principle suitable for data reduction in decentralized inference systems. Both parallel and tandem networks are studied and we focus on the cases where observations at decentralized nodes are conditionally dependent. For a parallel network, through the introduction of a hidden variable that induces conditional independence among the observations, the locally sufficient statistics, defined with respect to the hidden variable, are shown to be globally sufficient for the parameter of inference interest. For a tandem network, the notion of conditional sufficiency is introduced and the related theories and tools are developed. Finally, connections between the sufficiency principle and some distributed source coding problems are explored.
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