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Ara es mostren els items 24-43 de 68

    • Fast analysis and optimization of sparsely distributed partial modification problems 

      Fang, Xiaoxing; Heldring, Alexander; Rius Casals, Juan Manuel; Cao, Qunsheng (Institute of Electrical and Electronics Engineers (IEEE), 2022-08)
      Article
      Accés obert
      This article addresses the efficient numerical analysis of sparsely distributed small modifications in a large structure, that is, the sparsely distributed partial modification problem (SDPMP). A hierarchical matrix ...

    • Fast direct solution of method of moments linear system 

      Heldring, Alexander; Rius Casals, Juan Manuel; Tamayo Palau, José María; Parrón Granados, Josep; Úbeda Farré, Eduard (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2007-11)
      Article
      Accés obert
      A novel algorithm, the compressed block decomposition (CBD), is presented for highly accelerated direct (non iterative) method of moments (MoM) solution of electromagnetic scattering and radiation problems. The algorithm ...

    • Fast direct solution of the combined field integral equation 

      Heldring, Alexander; Tamayo Palau, José María; Rius Casals, Juan Manuel (2010)
      Text en actes de congrés
      Accés obert
      The Method of Moments for electromagnetic scattering and radiation problems is often used in conjunction with the EFIE because the EFIE allows the analysis of open surfaces. For electrically large closed surfaces, the ...

    • Fast shadowing computation in physical optics surface 

      Rius Casals, Juan Manuel; Carbo, Alex; Úbeda Farré, Eduard; Heldring, Alexander (2013)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      GRECO code has been updated by replacing the graphical processing technique for computation of Physical Optics surface integral by a hybrid CPU-graphical processing approach. The resulting code needs more CPU power for ...

    • Frequency extrapolation of IE-MEI linear system Coefficients in 2D 

      Rius Casals, Juan Manuel; Heldring, Alexander; Úbeda Farré, Eduard (Institute of Electrical and Electronics Engineers (IEEE), 2017)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      The Integral Equation MEI (IE-MEI) method for the sparsification of Method of Moments linear system matrix is revisited here. It achieves cpu computation time and storage memory requirements of order O(N ) (for 2D perfectly ...

    • Geometric algebra formulation of the Calderon Projector 

      López Menchón, Héctor; Rius Casals, Juan Manuel; Úbeda Farré, Eduard; Heldring, Alexander (2019)
      Comunicació de congrés
      Accés restringit per política de l'editorial
      Geometric Algebra provides a mathematical frame-work that allows to express many equations of physics in a more compact way [1]. It unifies the electric and the magnetic field in a single mathematical object: a multivector. ...

    • GRECO Code Rejuvenated: hybrid CPU-graphical processing 

      Rius Casals, Juan Manuel; Carbo, Alex; Úbeda Farré, Eduard; Heldring, Alexander (IEEE, 2013)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      GRECO code has been updated by replacing the graphical processing technique for computation of Physical Optics surface integral by a hybrid CPU-graphical processing approach. The resulting code needs more CPU power for ...

    • GRECO: 30 years of graphical processing techniques for RCS computation 

      Rius Casals, Juan Manuel; Úbeda Farré, Eduard; Heldring, Alexander (2018)
      Text en actes de congrés
      Accés obert
      This contribution to the special session in honor of Prof. Rafael Gómez-Martín will address the 30 year development of graphical processing techniques (GRECO) for fast computation of Radar Cross Section (RCS) of ...

    • Grid design benchmark on sheets with nonzero thickness 

      Úbeda Farré, Eduard; Rius Casals, Juan Manuel; Heldring, Alexander; López Menchón, Héctor (Universitat Politècnica de Catalunya. Remote Sensing, Antennas, Microwaves and Superconductivity Group (CommSensLab), 2022)
      Text en actes de congrés
      Accés obert
      The conventional scattering analysis of perfectly conducting sheets ignores the scattering contribution of the rim. The so-called thin-surface scheme arises from the discretization of the Electric-field Integral Equation ...

    • Improvements in randomized matrix compression methods for numerical analysis of antennas and scatterers 

      López Menchón, Héctor; Heldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan Manuel (Luis Landesa-Porras, 2023)
      Comunicació de congrés
      Accés obert
      We propose a randomized Pseudo Skeleton (or CUR) Approximation method to compress the H-matrices of linear systems that arise in the discretization of integral equations in electromagnetic scattering. This method is highly ...

    • Improving the accuracy of the adaptive cross approximation with a convergence criterion based on random sampling 

      Heldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan Manuel (2020-07-27)
      Article
      Accés obert
      The accuracy of the Adaptive Cross Approximation (ACA) algorithm, a popular method for the compression of low rank matrix blocks in Method of Moment computations, is sometimes seriously compromised by unpredictable errors ...

    • Integral Equation MEI (IE-MEI) analysis of homogeneus dielectric and plasmonic media in 2D 

      Rius Casals, Juan Manuel; Planes Conangla, Gerard; Úbeda Farré, Eduard; Heldring, Alexander (2015)
      Text en actes de congrés
      Accés obert
      This paper revisits the IE-MEI method and proposes a new formulation for high-loss didectric piecewise-homogeneous media. The aim of this work is lo assess if the bigh localization of surface plasmon polarltons helps in ...

    • Iterative method of moments solution of problems involving electrically large and concave geometries 

      Heldring, Alexander; Rius Casals, Juan Manuel; Úbeda Farré, Eduard (Institute of Electrical and Electronics Engineers (IEEE), 2013)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      This paper presents a study of the scaling with frequency (computational complexity) of preconditioned iterative solution, using the Multilevel Fast Multipole Method, of a class of radiation and scattering problems that ...

    • Low-rank matrix factorization method for multiscale simulations: a review 

      Li, Mengmeng; Ding, Dazhi; Heldring, Alexander; Hu, Jun; Chen, Rushan; Vecchi, Giuseppe (Institute of Electrical and Electronics Engineers (IEEE), 2021)
      Article
      Accés obert
      In this paper, a review of the low-rank factorization method is presented, with emphasis on their application to multiscale problems. Low-rank matrix factorization methods exploit the rankdeficient nature of coupling ...

    • Monte Carlo methods in electromagnetic scattering computations 

      López Menchón, Héctor; Heldring, Alexander; Úbeda Farré, Eduard; Rius Casals, Juan Manuel (Universitat Politècnica de Catalunya. Remote Sensing, Antennas, Microwaves and Superconductivity Group (CommSensLab), 2022)
      Text en actes de congrés
      Accés obert
      The solution of the electromagnetic scattering problem by the Method of Moments often leads to huge systems of equations that require large computational resources. In parallel computing environments, communication between ...

    • Multilevel adaptive cross approximation (MLACA) 

      Tamayo Palau, José María; Heldring, Alexander; Rius Casals, Juan Manuel (IEEE, 2009-06-30)
      Text en actes de congrés
      Accés obert
      In recent years, several methods have been developed for accelerating the iterative solution of the electromagnetic integral equations discretized by Method of Moments (MoM). Most of them are based on the compressibility ...

    • Multiscale compressed block decomposition for fast direct solution of method of moments linear system 

      Heldring, Alexander; Rius Casals, Juan Manuel; Tamayo Palau, José María; Parrón, Josep; Úbeda Farré, Eduard (2011-02)
      Article
      Accés restringit per política de l'editorial
      The multiscale compressed block decomposition algorithm (MS-CBD) is presented for highly accelerated direct (non iterative) solution of electromagnetic scattering and radiation problems with the method of moments (MoM). ...

    • Nested fast adaptive cross approximation algorithm for solving electromagnetic scattering problems 

      Fang, Xiaoxing; Heldring, Alexander; Rius Casals, Juan Manuel; Chen, Xinlei; Cao, Qunsheng (IEEE Microwave Theory and Techniques Society, 2020-09-28)
      Article
      Accés obert
      In this paper, a Nested Fast Adaptive Cross Approximation (NFACA) algorithm is presented to accelerate the solution of electromagnetic scattering problems. It is based on the Fast Adaptive Cross Approximation (FACA) and ...

    • New block ILU preconditioner scheme for numerical analysis of very large electromagnetic problems 

      Heldring, Alexander; Rius Casals, Juan Manuel; Ligthart, Leo P. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2002-03-31)
      Article
      Accés obert
      Large electromagnetic scattering and radiation problems are tackled by iterative solvers, which require the use of huge preconditioners. Most often, the incomplete LU decomposition (ILU) of the preconditioner is applied ...

    • New graphical processing technique for fast shadowing computation in PO surface integral 

      Rius Casals, Juan Manuel; Carbó Meseguer, Alexis; Bjerkemo, Jakob; Úbeda Farré, Eduard; Heldring, Alexander; Mallorquí Franquet, Jordi Joan; Broquetas Ibars, Antoni (2014-05-01)
      Article
      Accés restringit per política de l'editorial
      This paper presents a new graphical processing technique for fast computation of PO surface integral. In contrast with the original graphical processing approach introduced by the authors in 1993, the new one combines a ...