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  • Volumetric testing with wedges for a nonconforming discretization of the Electric-Field Integral Equation

     Ubeda Farre, Eduardo; Rius Casals, Juan-manuel; Heldring, Alexander
    IEEE International Symposium on Antennas and Propagation
    p. 2192-2193
    DOI: 10.1109/APS.2014.6905423
    Presentation's date: 2014-07
    Presentation of work at congresses

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    The discretization in Method of Moments (MoM) of the Electric-Field Integral Equation (EFIE) is traditionally carried out with divergence-conforming sets of basis functions, like the RWG set. This enforces the normal continuity of the current across the edges arising from the discretization and makes the quasi-singular Kernel contributions numerically manageable. However, these MoM-implementations of the EFIE show little flexibility when handling nonconformal meshes, normally arising from from the juxtaposition or interconnection of independent meshes in the modular design of composite objects. A nonconforming discretization of the EFIE is possible if the testing procedure is carried out over volumetric elements attached to the surface triangulation, inside the body. In this paper, we present a new nonconforming discretization of the EFIE, where wedges attached to the source triangles are used as testing volumetric elements.

  • Nonconforming discretization of the Magnetic-Field Integral Equation with volumetric testing

     Ubeda Farre, Eduardo; Rius Casals, Juan-manuel; Heldring, Alexander
    IEEE International Symposium on Antennas and Propagation
    p. 2194-2195
    DOI: 10.1109/APS.2014.6905424
    Presentation's date: 2014-07
    Presentation of work at congresses

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    The RWG-discretization in Method of Moments (MoM) of the Magnetic-Field and Electric-Field Integral Equations (MFIE, EFIE) show evident discrepancy in the computed RCS, especially for small objects with edges and corners. The nonconforming monopolar-RWG discretization of the MFIE exhibits a smaller a deviation with respect to the EFIE. The Combined-Field Integral Equation (CFIE), which arises from the combination of the EFIE and the MFIE, is very often implemented with the RWG basis functions, whereby some accuracy with respect to EFIE is lost too. In this paper, we present a new nonconforming monopolar-RWG discretization of the MFIE, based on testing the magnetic field over small tetrahedral elements attached to the surface, inside the body under analysis. This formulation is compatible with a successful nonconforming discretization of the EFIE with the monopolar-RWG expansion of the current and volumetric testing. This allows the development of a nonconforming discretization of the CFIE.

  • Grup de Teledetecció, Antenes, Microones i Superconductivitat

     Aguasca Sole, Alberto; Barlabe Dalmau, Antoni; Blanch Boris, Sebastian; Broquetas Ibars, Antoni; Camps Carmona, Adriano Jose; Cardama Aznar, Angel; Elias Fuste, Antonio; Duffo Ubeda, Nuria; Fabregas Canovas, Francisco Javier; Jofre Roca, Luis; Heldring, Alexander; López Martínez, Carlos; Mallorqui Franquet, Jordi Joan; O'callaghan Castella, Juan Manuel; Pradell Cara, Lluis; Rius Casals, Juan-manuel; Romeu Robert, Jordi; Torres Torres, Francisco; Ubeda Farre, Eduardo; Vall-llossera Ferran, Mercedes Magdalena; Duran Martinez, Israel; Wu, Lin; Gilasgar, Mitra; Lort Cuenca, Marc; Imbert Villa, Marc; Martin Alemany, Francisco; Chaparro Danon, David; Pablos Hernandez, Miriam; Pascual Biosca, Daniel; Park, Hyuk; Alonso Arroyo, Alberto; Onrubia Ibañez, Raul; Yam Ontiveros, Luis Eduardo; Rodriguez Silva, Juan Carlos; Piles Guillem, Maria; Deng, Xinping; Querol Borras, Jorge; Corbella Sanahuja, Ignasi
    Competitive project

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

     Heldring, Alexander; Rius Casals, Juan-manuel; Ubeda Farre, Eduardo
    International Conference on Electromagnetics in Advanced Applications
    p. 266-269
    DOI: 10.1109/ICEAA.2013.6632235
    Presentation's date: 2013-09-09
    Presentation of work at congresses

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    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 exhibits particularly slow convergence: problems involving electrically large, open and concave geometries. A comparison is presented between a well-known state of the art preconditioner (ILU) and a recently introduced preconditioning method, the Multiscale Compressed Block Decomposition.

  • Volumetric testing for a nonconforming discretization in method of moments of the electric-field surface integral equation

     Ubeda Farre, Eduardo; Rius Casals, Juan-manuel; Heldring, Alexander
    International Conference on Electromagnetics in Advanced Applications
    p. 121-124
    DOI: 10.1109/ICEAA.2013.6632202
    Presentation's date: 2013-09
    Presentation of work at congresses

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    Implementations in Method of Moments of the Electric-Field Integral Equation (EFIE) are traditionally carried out with divergence-conforming sets, with normal continuity of the current across edges. This gives rise to awkward implementations around junctions in composite dielectric objects. Also, RWG-implementations of the Combined-Field Integral Equation for sharp-edged objects suffer from some loss of accuracy. In this paper, we present a new nonconforming discretization of the EFIE, with no continuity requirements across edges. In the generation of the impedance elements, we employ a volumetric testing over a set of tetrahedral elements attached to the meshed surface to let the hyper-singular Kernel contributions numerically manageable. We show that the decomposition of the current into normally-continuous and discontinuous contributions leads to enhanced accuracy in the computed RCS.

  • Discretization of the EFIE in Method of Moments without continuity of the normal current component across edges

     Ubeda Farre, Eduardo; Rius Casals, Juan-manuel; Heldring, Alexander
    IEEE International Symposium on Antennas and Propagation
    p. 448-449
    DOI: 10.1109/APS.2013.6710885
    Presentation's date: 2013-07-08
    Presentation of work at congresses

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    The discretization in Method of Moments (MoM) of the Electric-Field Integral Equation (EFIE) is traditionally carried out by preserving the continuity of the normal component in the expansion of the current across the edges arising from the discretization. This allows the cancellation of the hyper-singular Kernel contributions arising from the discretization of the EFIE. Divergence-conforming sets, like the RWG set, appear then as suitable choices to generate successful MoM-EFIE implementations. In this paper, we present a novel MoM- discretization of the EFIE with the non-conforming monopolar- RWG basis functions, with jump discontinuities in the expanded normal component of the current. We show with RCS results that the new EFIE implementation shows good agreement with the traditional normal-continuous RWG-implementation.

  • Preconditioning the Electric Field Integral Equation with the MS-CBD method

     Heldring, Alexander; Ubeda Farre, Eduardo; Rius Casals, Juan-manuel
    Iberian Meeting on Computational Electromagnetics
    Presentation's date: 2013-05-14
    Presentation of work at congresses

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    A novel preconditioning scheme for Method of Moment computations is proposed. It consists of an adapted version of an accelerated direct solution method, the Multiscale Compressed Block Decomposition. It is of particular interest for accelerating the convergence of the iterative solution of open problems that are electrically large and exhibit strong concavity. For such problems, when solved with the Multilevel Fast Multipole Algorithm, the convergence is the main efficiency bottleneck. The novel scheme is compared with the de facto standard preconditioner ILU for a representative problem and shown to be considerably more efficient

  • Fast shadowing computation in physical optics surface

     Rius Casals, Juan-manuel; Carbo, Alex; Ubeda Farre, Eduardo; Heldring, Alexander
    Iberian Meeting on Computational Electromagnetics
    Presentation's date: 2013-05-14
    Presentation of work at congresses

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    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 complex radar targets, but is free from the pixel discretization noise inherent to graphical processing. It has the same accuracy as conventional Physical Optics computation, but is an order of magnitude faster than the most efficient implementations with NlogN shadowed facets detection

    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 complex radar targets, but is free from the pixel discretization noise inherent to graphical processing. It has the same accuracy as conventional Physical Optics computation, but is an order of magnitude faster than the most efficient implementations with NlogN shadowed facets detection.

  • The multiscale compressed block decomposition as a preconditioner for method of moments computations

     Heldring, Alexander; Ubeda Farre, Eduardo; Rius Casals, Juan-manuel
    European Conference on Antennas and Propagation
    p. 390-393
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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    A new preconditioner for Method of Moments computations is presented. It is based on a direct solver, the Multiscale Compressed Block Decomposition method, which has been adapted to reduce storage requirements and setup time. Numerical experiments show considerable improvement in overall efficiency in comparison with common preconditioners such as Incomplete LU decomposition, in particular for problems involving electrically large, open geometries.

    A new preconditioner for Method of Moments computations is presented. It is based on a direct solver, the Multiscale Compressed Block Decomposition method, which has been adapted to reduce storage requirements and setup time. Numerical experiments show considerable improvement in overall efficiency in comparison with common preconditioners such as Incomplete LU decomposition, in particular for problems involving electrically large, open geometries.

  • GRECO Code Rejuvenated: hybrid CPU-graphical processing

     Rius Casals, Juan-manuel; Carbo, Alex; Ubeda Farre, Eduardo; Heldring, Alexander
    European Conference on Antennas and Propagation
    p. 2348-2351
    Presentation's date: 2013-04-10
    Presentation of work at congresses

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    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 complex radar targets, but is free from the pixel discretization noise inherent to graphical processing. It has the same accuracy as conventional Physical Optics computation, but is an order of magnitude faster than the most efficient implementations with NlogN shadowed facets detection.

  • Dispositivos pasivos avanzados para cabezales multibanda, multimodo

     Rocas Cantenys, Eduard; Mateu Mateu, Jordi; Heldring, Alexander; González Arbesú, José María; Collado Gomez, Juan Carlos; Ubeda Farre, Eduardo
    Competitive project

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  • Sparsified ACA for accelerated iterative solution of the MoM linear system

     Heldring, Alexander; Rius Casals, Juan-manuel; Ubeda Farre, Eduardo; Tamayo Palau, Jose Maria
    Iberian Meeting on Computational Electromagnetics
    p. 13-15
    Presentation's date: 2011-11-02
    Presentation of work at congresses

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    A new algorithm, the Sparsified Adaptive Cross Approximation (SPACA) is presented for fast iterative solution of the Method of Moments linear system. Like ordinary ACA, it is a completely kernel-independent method, but it is faster and yields a higher compression rate than ordinary ACA, without compromising the accuracy. As an example, the RCS of a perfectly conducting sphere is computed using up to 786,432 basis functions. It is shown that SPACA exhibits close to NlogN complexity for this problem.

    Postprint (author’s final draft)

  • Block LU decomposition versus partitioned matrix inverse for compressed direct solution of method of moments linear system

     Heldring, Alexander; Rius Casals, Juan-manuel
    Iberian Meeting on Computational Electromagnetics
    p. 9-12
    Presentation's date: 2011-11-02
    Presentation of work at congresses

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  • Accelerated direct solution of the MoM linear system using block compression and nested factorization

     Heldring, Alexander; Rius Casals, Juan-manuel
    International Conference on Electromagnetics in Advanced Applications
    p. 636-639
    DOI: 10.1109/ICEAA.2011.6046415
    Presentation's date: 2011-09-13
    Presentation of work at congresses

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    A comparison is presented between different algorithms for direct (non-iterative) accelerated solution of the Method of Moments. The alternatives are common block LU factorization and Compressed Block Decomposition (CBD), and their respective nested, or Multi Scale (MS) implementations. The comparison includes theoretical considerations and numerical examples.

  • Multilevel adaptive cross approximation and direct evaluation method for fast and accurate discretization of electromagnetic inegral equations  Open access

     Tamayo Palau, José María
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    El objetivo de esta tesis es dotarse de una metodología de análisis dinámica en el tiempo que permite revalorar permanentemente la problemática de la escasez de agua dulce en función de la oferta y la demanda. Para ello, hemos tenido en cuenta las variaciones de sus factores conductores, y entre ellos sobre todo el de las necesidades en el desarrollo humano. La metodología es de manejo operativo, en la que se puedan introducir de manera rápida y sencilla los cambios en las variables que van a determinar la oferta y la demanda dinámica de agua dulce.La propuesta metodológica se caracteriza por varios puntos clave. En primer lugar, desarrollamos una discusión terminológica y conceptual en la que, a partir del estado del arte actual llegamos a definir los conceptos de la oferta y la demanda dinámica de agua dulce renovable como primer paso fundamental de nuestra metodología, elaborando un glosario terminológico y conceptual propio para este trabajo.A partir de la caracterización de la oferta y la demanda dinámica se analiza el escenario business as usual constatándose y valorándose la gravedad de la situación de los nueve países que forman la región del golfo de Guinea, debida fundamentalmente a la no existencia o a la no implementación de gestión de extracción, distribución y abastecimiento de agua dulce por falta de recursos económicos o voluntades políticas. Nuestro segundo paso metodológico permite corroborar la calificación usual de la situación de estos países como de escasez económica. Para poder cubrir esta etapa de la propuesta metodológica ha sido necesario resolver, también metodológicamente, la muy importante escasez de datos para la mayoría de países en desarrollo.Nuestra propuesta metodológica parte por supuesto de trabajar con la realidad, detectando inconvenientes y limitaciones al aplicarla al caso de estudio de los países de nuestra región. Una de estas limitaciones es claramente la falta de datos necesarios para elaborar nuestros escenarios o para determinar los estándares o confeccionar el nuevo índice; en la medida que se han ido presentando estas circunstancias, hemos recurrido a soluciones metodológicas que nos han permitido estimar nuevos datos a partir de correlaciones y/o extrapolaciones de los datos existentes.El siguiente punto clave y una de las aportaciones principales de este trabajo de propuesta metodológica es a partir de unas determinadas objetivizaciones de estándares de demanda de agua dulce ligados a unos niveles aceptables de bienestar y calidad de vida, reanalizar mediante la construcción y análisis de los escenarios de futuro correspondientes, las posibilidades y debilidades reales de estos países en relación con la escasez de agua dulce.El último punto clave es la elaboración de una propuesta de un índice que nos permite evaluar de forma sintética y rápida la situación de un país o región según el nivel de capacidad para satisfacer demandas de agua dulce correspondientes a un estándar de demanda establecido de forma clara y explícita. Dicho índice nos permite detectar de forma temprana posibles alertas que más allá de una escasez física o económica nos sean útiles (al igual que en el caso de la representación y el análisis de los resultados de los distintos escenarios de futuro) para la toma decisiones, en función de los objetivos pretendidos.La herramienta de apoyo para elaborar las representaciones de los escenarios es, en sí misma, otro elemento instrumental que además de tener una buena resolución de diseño gráfico, debe facilitar los cálculos necesarios para el análisis de los escenarios, así como almacenar la información de forma cómoda y en la que se puedan introducir cambios fácilmente.La metodología es una herramienta objetiva y útil dirigida a responsables políticos y técnicos, estudiosos e investigadores que dé soporte a la toma de decisiones y/o a la visualización de la valoración de la escasez de agua dulce en el marco de un pretendido desarrollo humano sostenible.

    This thesis describes a methodology for dynamic analysis over time that makes it possible to continually re-assess fresh-water scarcity as a function of supply and demand. The methodology takes into account variations in the driving factors, including, most importantly, human-development needs. The methodology can be controlled operationally. Changes in the variables that determine the dynamic fresh-water supply and demand can be entered quickly and easily.Our methodological proposal contains several key points. We begin with a discussion of terminology and concepts. Taking the current state of the art as our starting point, as a fundamental first step in our methodology we define the concepts of dynamic renewable fresh-water supply and demand. We then present a glossary of the terms and concepts used in this thesis.Following the characterisation of dynamic supply and demand, we analyse the "business-as-usual" scenario. We point out the seriousness of the situation in the nine Gulf of Guinea countries. The fundamental reason for this situation is the non-existence or non-implementation of policies aimed at extracting, distributing and supplying fresh water, due to a lack of economic resources or political will. The second step in our methodology is to corroborate the usual description of the situation in these countries, particularly in terms of the economic scarcity that characterises them. To properly complete this stage of the methodology, it has been necessary to find a solution to the inadequacy of the data available in most developing countries.Our proposal works with reality, which involves detecting disadvantages and limitations when applying the methodology in the countries of this particular region. One such limitation, clearly, is the lack of the necessary data for constructing the scenarios, determining the standards and creating the new index; as these circumstances have arisen, we have implemented methodological solutions that have enabled us to estimate new data on the basis of correlations and/or extrapolations of existing data.The next key point is also one of the main contributions of this methodological proposal. We set the goal of achieving certain standards of fresh-water demand based on acceptable levels of welfare and quality of life. Then, by constructing and analysing the corresponding future scenarios, we re-examine the real possibilities and weaknesses of each country as relates to the scarcity of fresh water.The last key point of our proposal is the generation of an index that enables us to evaluate, quickly and synthetically, the situation of a particular country or region on the basis of its capacity to satisfy fresh-water demand in a way that meets a clearly and specifically defined standard. This index enables the early detection of possible problems that go beyond physical or economic scarcity. Like the representation and analysis of the results of the various future scenarios, this early-warning system will enable decisions to be made in accordance with the established goals.The support tool used to generate the representations of the scenarios must have good graphic-design resolution, be able to make the calculations necessary for analysing the scenarios, and store the information in a practical way that allows changes to be entered easily.This methodology is meant to be used by politicians, engineers, scholars and researchers as a useful and objective support tool for decision-making and/or visualising levels of fresh-water scarcity as part of larger efforts to achieve the goal of sustainable human development.

  • Multilevel adaptive cross approximation and direct evaluation method for fast and accurate discretization of electromagnetic integral equations  Open access  awarded activity

     Tamayo Palau, José María
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    El objetivo de esta tesis es dotarse de una metodología de análisis dinámica en el tiempo que permite revalorar permanentemente la problemática de la escasez de agua dulce en función de la oferta y la demanda. Para ello, hemos tenido en cuenta las variaciones de sus factores conductores, y entre ellos sobre todo el de las necesidades en el desarrollo humano. La metodología es de manejo operativo, en la que se puedan introducir de manera rápida y sencilla los cambios en las variables que van a determinar la oferta y la demanda dinámica de agua dulce.La propuesta metodológica se caracteriza por varios puntos clave. En primer lugar, desarrollamos una discusión terminológica y conceptual en la que, a partir del estado del arte actual llegamos a definir los conceptos de la oferta y la demanda dinámica de agua dulce renovable como primer paso fundamental de nuestra metodología, elaborando un glosario terminológico y conceptual propio para este trabajo.A partir de la caracterización de la oferta y la demanda dinámica se analiza el escenario business as usual constatándose y valorándose la gravedad de la situación de los nueve países que forman la región del golfo de Guinea, debida fundamentalmente a la no existencia o a la no implementación de gestión de extracción, distribución y abastecimiento de agua dulce por falta de recursos económicos o voluntades políticas. Nuestro segundo paso metodológico permite corroborar la calificación usual de la situación de estos países como de escasez económica. Para poder cubrir esta etapa de la propuesta metodológica ha sido necesario resolver, también metodológicamente, la muy importante escasez de datos para la mayoría de países en desarrollo.Nuestra propuesta metodológica parte por supuesto de trabajar con la realidad, detectando inconvenientes y limitaciones al aplicarla al caso de estudio de los países de nuestra región. Una de estas limitaciones es claramente la falta de datos necesarios para elaborar nuestros escenarios o para determinar los estándares o confeccionar el nuevo índice; en la medida que se han ido presentando estas circunstancias, hemos recurrido a soluciones metodológicas que nos han permitido estimar nuevos datos a partir de correlaciones y/o extrapolaciones de los datos existentes.El siguiente punto clave y una de las aportaciones principales de este trabajo de propuesta metodológica es a partir de unas determinadas objetivizaciones de estándares de demanda de agua dulce ligados a unos niveles aceptables de bienestar y calidad de vida, reanalizar mediante la construcción y análisis de los escenarios de futuro correspondientes, las posibilidades y debilidades reales de estos países en relación con la escasez de agua dulce.El último punto clave es la elaboración de una propuesta de un índice que nos permite evaluar de forma sintética y rápida la situación de un país o región según el nivel de capacidad para satisfacer demandas de agua dulce correspondientes a un estándar de demanda establecido de forma clara y explícita. Dicho índice nos permite detectar de forma temprana posibles alertas que más allá de una escasez física o económica nos sean útiles (al igual que en el caso de la representación y el análisis de los resultados de los distintos escenarios de futuro) para la toma decisiones, en función de los objetivos pretendidos.La herramienta de apoyo para elaborar las representaciones de los escenarios es, en sí misma, otro elemento instrumental que además de tener una buena resolución de diseño gráfico, debe facilitar los cálculos necesarios para el análisis de los escenarios, así como almacenar la información de forma cómoda y en la que se puedan introducir cambios fácilmente.La metodología es una herramienta objetiva y útil dirigida a responsables políticos y técnicos, estudiosos e investigadores que dé soporte a la toma de decisiones y/o a la visualización de la valoración de la escasez de agua dulce en el marco de un pretendido desarrollo humano sostenible.

    This thesis describes a methodology for dynamic analysis over time that makes it possible to continually re-assess fresh-water scarcity as a function of supply and demand. The methodology takes into account variations in the driving factors, including, most importantly, human-development needs. The methodology can be controlled operationally. Changes in the variables that determine the dynamic fresh-water supply and demand can be entered quickly and easily.Our methodological proposal contains several key points. We begin with a discussion of terminology and concepts. Taking the current state of the art as our starting point, as a fundamental first step in our methodology we define the concepts of dynamic renewable fresh-water supply and demand. We then present a glossary of the terms and concepts used in this thesis.Following the characterisation of dynamic supply and demand, we analyse the "business-as-usual" scenario. We point out the seriousness of the situation in the nine Gulf of Guinea countries. The fundamental reason for this situation is the non-existence or non-implementation of policies aimed at extracting, distributing and supplying fresh water, due to a lack of economic resources or political will. The second step in our methodology is to corroborate the usual description of the situation in these countries, particularly in terms of the economic scarcity that characterises them. To properly complete this stage of the methodology, it has been necessary to find a solution to the inadequacy of the data available in most developing countries.Our proposal works with reality, which involves detecting disadvantages and limitations when applying the methodology in the countries of this particular region. One such limitation, clearly, is the lack of the necessary data for constructing the scenarios, determining the standards and creating the new index; as these circumstances have arisen, we have implemented methodological solutions that have enabled us to estimate new data on the basis of correlations and/or extrapolations of existing data.The next key point is also one of the main contributions of this methodological proposal. We set the goal of achieving certain standards of fresh-water demand based on acceptable levels of welfare and quality of life. Then, by constructing and analysing the corresponding future scenarios, we re-examine the real possibilities and weaknesses of each country as relates to the scarcity of fresh water.The last key point of our proposal is the generation of an index that enables us to evaluate, quickly and synthetically, the situation of a particular country or region on the basis of its capacity to satisfy fresh-water demand in a way that meets a clearly and specifically defined standard. This index enables the early detection of possible problems that go beyond physical or economic scarcity. Like the representation and analysis of the results of the various future scenarios, this early-warning system will enable decisions to be made in accordance with the established goals.The support tool used to generate the representations of the scenarios must have good graphic-design resolution, be able to make the calculations necessary for analysing the scenarios, and store the information in a practical way that allows changes to be entered easily.This methodology is meant to be used by politicians, engineers, scholars and researchers as a useful and objective support tool for decision-making and/or visualising levels of fresh-water scarcity as part of larger efforts to achieve the goal of sustainable human development.

  • Simulation of shipborne small HF antennas with RWG discretization and fast solver

     Rius Casals, Juan-manuel; Jofre Roca, Luis; Tamayo Palau, Jose Maria; Heldring, Alexander; Ubeda Farre, Eduardo
    IEEE International Conference on Wireless Information Technology and Systems
    DOI: 10.1109/ICWITS.2010.5611892
    Presentation's date: 2010-09-01
    Presentation of work at congresses

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    In this paper, an alternative approach has been used to analyze an electrically small antenna (1.2m in the 2-30 MHz band) in a large ship (238m length) using a generic EFIE simulation code with Rao, Wilton and Glisson (RWG) basis functions, with the minimum necessary modifications to tackle the lowfrequency and multiscale issues that lead to a very poorly conditioned linear system.

  • Access to the full text
    Fast direct solution of the combined field integral equation  Open access

     Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel
    URSI Commission B International Symposium on Electromagnetic Theory
    Presentation's date: 2010-08-17
    Presentation of work at congresses

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    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 CFIE is often much more efficient because it yields a well conditioned impedance matrix. This is particularly important when an iterative solution method is used. This paper compares the EFIE and the CFIE for a novel fast direct (non-iterative) solution method, the Multiscale Compressed Block Decomposition method.

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    Accelerated direct solution of the MoM-VIE for dielectric scatterers  Open access

     Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel; Ubeda Farre, Eduardo
    Iberian Meeting on Computational Electromagnetics
    p. 25-29
    Presentation's date: 2010-05-19
    Presentation of work at congresses

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    The Multiscale Compressed Block Decomposition algorithm (MS-CBD), a direct (non-iterative) linear solver, is applied to accelerate the solution of the MoM-VIE formulation for dielectric scatterers. Numerical solutions are presented for problems with several hundreds of thousands of unknowns. Asymptotically (with respect to the electrical size of the problem), the solution time scales with the number of unknowns squared. The numerical examples confirm this theoretical value.

  • Software framework for integration of method of moments kernels with direct or iterative fast solvers

     Rius Casals, Juan-manuel; Herrero, J. A.; Tamayo Palau, Jose Maria; Heldring, Alexander; Ubeda Farre, Eduardo; Parrón, Josep; López-Peña, Sergio; Polimeridis, Athanasios G.; Mosig, Juan Ramón; Espinosa, Hugo; Boag, Amir
    European Conference on Antennas and Propagation
    p. 1-2
    Presentation's date: 2010-04-15
    Presentation of work at congresses

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  • Direct MoM solution of electrically large problems with N2 complexity

     Heldring, Alexander; Rius Casals, Juan-manuel; Tamayo Palau, Jose Maria
    European Conference on Antennas and Propagation
    Presentation's date: 2010-04-15
    Presentation of work at congresses

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  • Analysis of numerical integration in the evaluation of hyper-singular integrals in Galerkin surface integral equation formulations via the direct evaluation method

     Tamayo Palau, Jose Maria; Polimeridis, Athanasios G.; Rius Casals, Juan-manuel; Heldring, Alexander; Mosig, Juan Ramón
    European Conference on Antennas and Propagation
    p. 1-5
    Presentation's date: 2010-04-16
    Presentation of work at congresses

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  • TECNOLOGIA Y NUEVAS TECNICAS DE DISEÑO PARA INTEGRACION EN CHIP DE CABECERAS DE MICROONDAS

     Mateu Mateu, Jordi; Ubeda Farre, Eduardo; González Arbesú, José María; Heldring, Alexander; Collado Gomez, Juan Carlos
    Competitive project

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  • Framework for integration of fast solvers in method of moments kernels

     Rius Casals, Juan-manuel; Tamayo Palau, Jose Maria; Heldring, Alexander; Parrón, Josep; Ubeda Farre, Eduardo
    LEMA-EPFL Workshop on Integral Techniques for Electromagnetics
    Presentation's date: 2009-09-08
    Presentation of work at congresses

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    Application of Multilevel Adaptive Cross Approximation (MLACA) to electromagnetic scattering and radiation problems  Open access

     Tamayo Palau, Jose Maria; Heldring, Alexander; Rius Casals, Juan-manuel
    International Conference on Electromagnetics in Advanced Applications
    p. 1-4
    Presentation's date: 2009-09-14
    Presentation of work at congresses

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    On the degrees of freedom in the interaction between sets of elementary scatterers  Open access

     Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel
    European Conference on Antennas and Propagation
    p. 2413-2416
    Presentation's date: 2009-03
    Presentation of work at congresses

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    A series of numerical experiments has been executed to investigate the number of degrees of freedom in the interaction between large scattering bodies. The relation between degrees of freedom and operating frequency establishes the computational complexity for integral equation methods fast solvers based on matrix block compression. In 2D the theoretical asymptotic relation for large frequency soon becomes clear. On the other hand, in 3D even a tendency towards the asymptotic value fails to appear for bodies of hundreds of wavelengths in diameter.

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    Compression of the MoM matrix using macrobasis functions with a full-controlable accuracy  Open access

     Tamayo Palau, Jose Maria; Heldring, Alexander; Rius Casals, Juan-manuel
    European Conference on Antennas and Propagation
    Presentation of work at congresses

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    A new accuracy-controlable method for compressing the MoM impedance matrix of an electromagnetic problem based on a basis change plus a truncation with a threshold is presented here. The idea is to switch to singular basis functions, which are defined on relatively large subdomains of the object, representing perfectly the far field of the subdomain and yielding compression for well-separated blocks. Although the construction of the matrix is not computationally efficient compared with other matrix compression methods, it is still quite interesting from a theoretical point of view. Furthermore, it clearly explains certain characteristics of some of those methods, particularly the errors in the solution of those based in pseudoglobal functions.

    Postprint (author’s final draft)

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    Multilevel adaptive cross approximation (MLACA)  Open access

     Tamayo Palau, Jose Maria; Heldring, Alexander; Rius Casals, Juan-manuel
    2012 IEEE International Symposium on Antennas and Propagation
    p. 1-4
    Presentation of work at congresses

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    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 of parts of the MoM matrix when they correspond to the interaction between two distant boxes. Among them, a promising one is the Adaptive Cross Approximation (ACA) [1] which combined with a SVD recompression achieves very good results, especially for moderately large number of unknowns N. In this paper we propose a multilevel implementation of the ACA leading to a highly enhanced compression rate.

  • Polynomial Interpolators of variable order for Method of Moments acceleration with the Multilevel Field Interpolation Algorithm (MLFIA)

     Espinosa, Hugo G; Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel
    IEEE International Antennas and Propagation Symposium
    Presentation of work at congresses

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  • Progress in MoM Solution of Electromagnetic Scattering and Radiation at UPC AntennaLab

     Heldring, Alexander; Tamayo Palau, Jose Maria; Ubeda Farre, Eduardo; Rius Casals, Juan-manuel
    VI Encuentro Ibérico de Electromagnetismo Computacional
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  • Multiscale CBD for Fast Direct Solution of MoM Linear System

     Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel; Parrón, J; Ubeda Farre, Eduardo
    IEEE International Antennas and Propagation Symposium
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  • Application of the Multilevel Field Interpolation Algorithm to Large PEC Structures in 2-D

     Espinosa, H G; Heldring, Alexander; Rius Casals, Juan-manuel
    IEEE International Antennas and Propagation Symposium
    Presentation of work at congresses

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  • Multilevel MDA-CBI for Fast Direct Solution of Large Scattering and Radiation Problems

     Heldring, Alexander; Rius Casals, Juan-manuel; Tamayo Palau, Jose Maria; Parrón, J
    IEEE International Antennas and Propagation Symposium
    Presentation of work at congresses

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  • Advances in Numerical Electromagnetics at UPC AntennaLab

     Ubeda Farre, Eduardo; Heldring, Alexander; Rius Casals, Juan-manuel; Espinosa, H; Tamayo Palau, Jose Maria; Parron, J
    Computational Electromagnetics Workshop
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  • The MDA-SVD Algorithm for Fast Direct or Iterative Solution of Discrete Integral Equations

     Rius Casals, Juan-manuel; Heldring, Alexander; Parron, J; Tamayo Palau, Jose Maria
    European Conference on Antennas and Propagation (EuCAP 2007)
    Presentation of work at congresses

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  • Integration of CBLU Solver in the Finite Array GSM Code

     Rubio, J.; Heldring, Alexander; Rius Casals, Juan-manuel; González, M A; Zapata, J
    European Conference on Antennas and Propagation (EuCAP 2007)
    Presentation of work at congresses

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  • Advances in Numerical Electromagnetics at UPC and UAB

     Heldring, Alexander; Ubeda Farre, Eduardo; Rius Casals, Juan-manuel; Espinosa, H; Tamayo Palau, Jose Maria; Parrón, J
    V Encuentro Ibérico de Electromagnetismo Computacional
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  • Analysis of an artifical magnetic reflector using MLMDA

     Parrón, J; Junkin, G; Villarino Villarino, Ramon; Heldring, Alexander; González Arbesú, José María
    V Encuentro Ibérico de Electromagnetismo Computacional
    Presentation of work at congresses

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  • Integration of UPC-UAB Fast Solvers into the Antenna Simulation Software of UNEX-UPM, KUL, UPV and EPFL ACE Partners

     Heldring, Alexander; Rius Casals, Juan-manuel; Tamayo Palau, Jose Maria; Rubio, J.; Zapata, J; Volski, V; Vandenbosh, G; Mattes, M; Valero, A; Parrón, J
    European Conference on Antennas and Propagation (EuCAP 2007)
    Presentation of work at congresses

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  • Miniaturización y mejora de cabeceras de radiofrecuencia mediante el uso de nuevos materiales y metamateriales

     Collado Gomez, Juan Carlos; Heldring, Alexander; Santos Blanco, María Concepción; O'callaghan Castella, Juan Manuel; Ubeda Farre, Eduardo; González Arbesú, José María; Mateu Mateu, Jordi
    Competitive project

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  • Multilevel Field Interpolation Algorithm for MoM

     Espinosa, Hugo G; Heldring, Alexander; Rius Casals, Juan-manuel
    2006 IEEE Antennas and Propagation Society International Symposium
    Presentation of work at congresses

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  • New and more efficient formulation of MLMDA for arbitrary 3D antennas and scatterers

     Rius Casals, Juan-manuel; Parrón, Josep; Heldring, Alexander; Tamayo Palau, Jose Maria
    European Conference on Antennas and Propagation: EUCAP 2006
    Presentation of work at congresses

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  • Fast Direct Solution of the Method of Moments Linear System

     Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel
    European Conference on Antennas and Propagation: EUCAP 2006
    Presentation of work at congresses

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  • Multilevel Field Interpolation Algorithm for Large PEC Objects

     Espinosa, H; Heldring, Alexander; Tamayo Palau, Jose Maria; Rius Casals, Juan-manuel
    European Conference on Antennas and Propagation: EUCAP 2006
    Presentation of work at congresses

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  • Integration of UPC AntennaLab Block-LU direct solver in MoM codes

     Rius Casals, Juan-manuel; Heldring, Alexander; Espinosa, H; Tamayo Palau, Jose Maria; Mattes, M; Valero, A; Parrón, J
    European Conference on Antennas and Propagation: EUCAP 2006
    Presentation of work at congresses

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  • Algunas mejoras de la exactitud y eficiencia de la formulación de ecuaciones integrales para análisis de radiación y difracción

     Rius Casals, Juan-manuel; Ubeda Farre, Eduardo; Heldring, Alexander; Espinosa, Hugo Y José María Tamayo; Tamayo Palau, Jose Maria
    IV Encuentro Ibérico de Electromagnetismo Computacional
    p. 83-88
    Presentation of work at congresses

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  • Efficient solution of the EFIE for relatively thick wires including end-caps for near-field computation

     Heldring, Alexander; Rius Casals, Juan-manuel
    International Conference on Electromagnetic Near-Field Characterization & Imaging
    p. 150-154
    Presentation of work at congresses

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  • Highly accurate thin wire MoM with low order basis functions

     Heldring, Alexander; Rius Casals, Juan-manuel
    International Conference on Electromagnetics in Advanced Applications
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  • Efficient Full-Kernel Evaluation in the Thin-Wire Electric Field Integral Equation

     Heldring, Alexander; Rius Casals, Juan-manuel
    2004 URSI Commission B International Symposium on Electromagnetic Theory
    p. 831-833
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  • Efficient Full Kernel Calculation for Wire Antennas

     Heldring, Alexander; Rius Casals, Juan-manuel
    IEEE INTERNATIONAL ANTENNAS AND PROPAGATION SYMPOSIUM (AP-S)
    Presentation of work at congresses

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