The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Kin Tat Ho - One of the best experts on this subject based on the ideXlab platform.
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QCMC: quasi-Conformal parameterizations for multiply-connected domains
Advances in Computational Mathematics, 2015Co-Authors: Kin Tat HoAbstract:This paper presents a method to compute the quasi-Conformal parameterization (QCMC) for a multiply-connected 2D domain or surface. QCMC computes a quasi-Conformal map from a multiply-connected domain S onto a punctured disk DS associated with a given Beltrami differential. The Beltrami differential, which measures the Conformality distortion, is a complex-valued function μ:S??$\mu :S\to \mathbb {C}$ with supremum norm strictly less than 1. Every Beltrami differential gives a Conformal structure of S. Hence, the Conformal module of DS, which are the radii and centers of the inner circles, can be fully determined by μ, up to a Mobius transformation. In this paper, we propose an iterative algorithm to simultaneously search for the Conformal module and the optimal quasi-Conformal parameterization. The key idea is to minimize the Beltrami energy with the Conformal module of the parameter domain incorporated. The optimal solution is our desired quasi-Conformal parameterization onto a punctured disk. The parameterization of the multiply-connected domain simplifies numerical computations and has important applications in various fields, such as in computer graphics and vision. Experiments have been carried out on synthetic data together with real multiply-connected Riemann surfaces. Results show that our proposed method can efficiently compute quasi-Conformal parameterizations of multiply-connected domains and outperforms other state-of-the-art algorithms. Applications of the proposed parameterization technique have also been explored.
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QCMC: Quasi-Conformal Parameterizations for Multiply-connected domains
arXiv: Computational Geometry, 2014Co-Authors: Kin Tat HoAbstract:This paper presents a method to compute the {\it quasi-Conformal parameterization} (QCMC) for a multiply-connected 2D domain or surface. QCMC computes a quasi-Conformal map from a multiply-connected domain $S$ onto a punctured disk $D_S$ associated with a given Beltrami differential. The Beltrami differential, which measures the Conformality distortion, is a complex-valued function $\mu:S\to\mathbb{C}$ with supremum norm strictly less than 1. Every Beltrami differential gives a Conformal structure of $S$. Hence, the Conformal module of $D_S$, which are the radii and centers of the inner circles, can be fully determined by $\mu$, up to a M\"obius transformation. In this paper, we propose an iterative algorithm to simultaneously search for the Conformal module and the optimal quasi-Conformal parameterization. The key idea is to minimize the Beltrami energy subject to the boundary constraints. The optimal solution is our desired quasi-Conformal parameterization onto a punctured disk. The parameterization of the multiply-connected domain simplifies numerical computations and has important applications in various fields, such as in computer graphics and vision. Experiments have been carried out on synthetic data together with real multiply-connected Riemann surfaces. Results show that our proposed method can efficiently compute quasi-Conformal parameterizations of multiply-connected domains and outperforms other state-of-the-art algorithms. Applications of the proposed parameterization technique have also been explored.
H Y Zhang - One of the best experts on this subject based on the ideXlab platform.
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a new property of the electromagnetic yang mills Conformal gravity system in spherical symmetry
Nuclear Physics, 2019Co-Authors: H Y ZhangAbstract:Abstract We find a new property in W 2 -Conformal gravity in spherical symmetry. We demonstrate that the charge of the electromagnetic field varies with respect to the partial scaling symmetry (Conformal transformations in subspaces of a spacetime) in the Conformal gravity. We find that the electric and magnetic charges can vanish or appear via partial Conformal transformations for the on-shell configurations in the Conformal gravity. We find a solution of a Yang–Mills SU(2)-charged black hole in the Conformal gravity, and further demonstrate that the SU(2) charge has similar properties with electromagnetic magnetic charges in the Conformal gravity. We demonstrate how to imbed the electromagnetic and Yang–Mills SU(2) gauge field into the Conformal gravity via such a symmetry. We make a brief discussion about the possibility to extend this argument to the Einstein gravity.
J M Wang - One of the best experts on this subject based on the ideXlab platform.
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Non-Hertzian Conformal contact at wheel/rail interface
Proceedings of the 1995 IEEE ASME Joint Railroad Conference, 1995Co-Authors: Huimin Wu, J M WangAbstract:The Transportation Technology Center conducted an investigation to study non-Hertzian Conformal contact, roller Conformal contact, and Hertzian counterformal contact at the wheel/rail interface. The computational results show that a significant error (up to 72 percent) in both stress distribution and contact area may be produced by using the approximate Hertzian Conformal solution to solve non-Hertzian Conformal contact, which is the current practice in most vehicle dynamic simulation models. An even greater error (up to 400 percent) may be produced by using the Hertzian counterformal solution to solve non-Hertzian Conformal contact. The study also shows that, in elastic contact, the separation function of two contact bodies plays a dominant role in the determination of contact stresses and area. It is not proper to present the separation function by a quadratic function in non-Hertzian Conformal contacts.
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non hertzian Conformal contact at wheel rail interface
IEEE ASME Joint Railroad Conference, 1995Co-Authors: Huimin Wu, J M WangAbstract:The Transportation Technology Center conducted an investigation to study non-Hertzian Conformal contact, roller Conformal contact, and Hertzian counterformal contact at the wheel/rail interface. The computational results show that a significant error (up to 72 percent) in both stress distribution and contact area may be produced by using the approximate Hertzian Conformal solution to solve non-Hertzian Conformal contact, which is the current practice in most vehicle dynamic simulation models. An even greater error (up to 400 percent) may be produced by using the Hertzian counterformal solution to solve non-Hertzian Conformal contact. The study also shows that, in elastic contact, the separation function of two contact bodies plays a dominant role in the determination of contact stresses and area. It is not proper to present the separation function by a quadratic function in non-Hertzian Conformal contacts. >
Slava Rychkov - One of the best experts on this subject based on the ideXlab platform.
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EPFL Lectures on Conformal Field Theory in D>= 3 Dimensions
arXiv, 2016Co-Authors: Slava RychkovAbstract:This is a writeup of lectures given at the EPFL Lausanne in the fall of 2012. The topics covered: physical foundations of Conformal symmetry, Conformal kinematics, radial quantization and the OPE, and a very basic introduction to Conformal bootstrap.
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spinning Conformal blocks
Journal of High Energy Physics, 2011Co-Authors: Miguel S Costa, Joao Penedones, David Poland, Slava RychkovAbstract:For Conformal field theories in arbitrary dimensions, we introduce a method to derive the Conformal blocks corresponding to the exchange of a traceless symmetric tensor appearing in four point functions of operators with spin. Using the embedding space formalism, we show that one can express all such Conformal blocks in terms of simple differential operators acting on the basic scalar Conformal blocks. This method gives all Conformal blocks for Conformal field theories in three dimensions. We demonstrate how this formalism can be applied in a few simple examples.
Huimin Wu - One of the best experts on this subject based on the ideXlab platform.
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Non-Hertzian Conformal contact at wheel/rail interface
Proceedings of the 1995 IEEE ASME Joint Railroad Conference, 1995Co-Authors: Huimin Wu, J M WangAbstract:The Transportation Technology Center conducted an investigation to study non-Hertzian Conformal contact, roller Conformal contact, and Hertzian counterformal contact at the wheel/rail interface. The computational results show that a significant error (up to 72 percent) in both stress distribution and contact area may be produced by using the approximate Hertzian Conformal solution to solve non-Hertzian Conformal contact, which is the current practice in most vehicle dynamic simulation models. An even greater error (up to 400 percent) may be produced by using the Hertzian counterformal solution to solve non-Hertzian Conformal contact. The study also shows that, in elastic contact, the separation function of two contact bodies plays a dominant role in the determination of contact stresses and area. It is not proper to present the separation function by a quadratic function in non-Hertzian Conformal contacts.
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non hertzian Conformal contact at wheel rail interface
IEEE ASME Joint Railroad Conference, 1995Co-Authors: Huimin Wu, J M WangAbstract:The Transportation Technology Center conducted an investigation to study non-Hertzian Conformal contact, roller Conformal contact, and Hertzian counterformal contact at the wheel/rail interface. The computational results show that a significant error (up to 72 percent) in both stress distribution and contact area may be produced by using the approximate Hertzian Conformal solution to solve non-Hertzian Conformal contact, which is the current practice in most vehicle dynamic simulation models. An even greater error (up to 400 percent) may be produced by using the Hertzian counterformal solution to solve non-Hertzian Conformal contact. The study also shows that, in elastic contact, the separation function of two contact bodies plays a dominant role in the determination of contact stresses and area. It is not proper to present the separation function by a quadratic function in non-Hertzian Conformal contacts. >
