Exploració per tema "Dispersió (Física)"
Ara es mostren els items 1-20 de 31
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A new general method to compute dispersion errors on Cartesian stretched meshes for both linear and non-linear operators
(2022-02-01)
Article
Accés restringit per política de l'editorialThe present article presents a new analysis for the dispersion error and the methodology to evaluate it numerically. Here we present the spectral properties of several convective schemes, including non-linear ones, on ... -
Analisi d'estructures conductores planes 2D-periodiques infinites en l'espai lliure a partir de la discretitzacio en Metode dels moments de la convolucio del corrent superficial amb la Funcio de Green Floquet-periodica
(Universitat Politècnica de Catalunya, 2011-06-21)
Treball Final de Grau
Accés obert -
Beam focusing in reflections from flat subwavelength diffraction gratings
(2014-03-10)
Article
Accés obertWe predict that narrow beams, reflecting from flat subwavelength diffraction gratings, can focus. The effect is shown for the beams of electromagnetic radiation; however, it should be observable for beams of waves of ... -
Comparison of expansion-based explicit time-integration schemes for acoustic wave propagation
(Society of Exploration Geophysicists, 2020-04-14)
Article
Accés obertWe have developed a von Neumann stability and dispersion analysis of two time-integration techniques in the framework of Fourier pseudospectral (PS) discretizations of the second-order wave equation. The first technique ... -
Competition between fast- and slow-diffusing species in non-homogeneous environments
(2016-04-21)
Article
Accés obertWe study an individual-based model in which two spatially distributed species, characterized by different diffusivities, compete for resources. We consider three different ecological settings. In the first, diffusing faster ... -
Flat lensing by periodic loss-modulated materials
(2013-09-23)
Article
Accés obertWe propose a flat lensing effect using a periodic loss-modulated material. In particular, we consider a two-dimensional square and rhombic arrangement of lossy cylinders embedded in a host media with the same refractive ... -
Implementació del precondicionador SAI com a eina acceleradora en el càlcul de la Secció Recta Radar de blancs conductors
(Universitat Politècnica de Catalunya, 2009-07-17)
Treball Final de Grau
Accés obert -
Influencia del número de elementos reemisores en el modelado de difusores durante la etapa de optimización
(2016-06)
Article
Accés obertEn el marco de trabajo del diseño óptico, el fenómeno de la difusión normalmente queda relegado a la fase final del estudio de tolerancias, momento en el que se valora su influencia en el sismtea ya diseñado. El hecho de ... -
Low-energy scattering parameters: A theoretical derivation of the effective range and scattering length for arbitrary angular momentum
(AMER INST PHYSICS, 2023-02-01)
Article
Accés obertThe most important parameters in the study of low-energy scattering are the s-wave and p-wave scattering lengths and the s-wave effective range. We solve the scattering problem and find two useful formulas for the scattering ... -
Method of moments applied to the analysis of rough surfaces modelled by fractals
(2000)
Text en actes de congrés
Accés obertThe Scattering and Emissivity of rough surfaces involve solutions to non-linear differential equations. Different approaches have been used in the literature to obtain approximate solutions under some hypothesis. For example ... -
Métodos avanzados para la medida de la dispersión cromática a frecuencias ópticas
(Universitat Politècnica de Catalunya, 2011-09-28)
Projecte/Treball Final de Carrera
Accés obertEnglish: Advanced Methods for the Measurement of Chromatic Dispersion at Optical Frequencies. To use the methods, we must first study the phenomenon of dispersion, and how we see the effect it has on the phase and envelope ... -
Microwave invisibility cloaks based on frequency selective surfaces
(Universitat Politècnica de Catalunya, 2016-09)
Projecte Final de Màster Oficial
Accés obertIn this report the successful design, manufacturing and testing of Mantle Cloaking is presented. This relatively new technique goes beyond traditional metamaterial-based alternatives in the search for effective invisibility ... -
Mixed simulation of multiple elastic scattering of electrons and positrons using partial-wave differential cross sections
(2001-05)
Article
Accés restringit per política de l'editorialWe describe an algorithm for mixed (class II) simulation of electron multiple elastic scattering using numerical differential cross-sections (DCS), which is applicable in a wide energy range, from ~100 eV to ~1 GeV. DCSs ... -
Mobile impurity in a Bose-Einstein condensate and the orthogonality catastrophe
(American Physical Society, 2021-01-01)
Article
Accés obertWe analyze the properties of an impurity in a dilute Bose-Einstein condensate (BEC). First the quasiparticle residue of a static impurity in an ideal BEC is shown to vanish with increasing particle number as a stretched ... -
Modelling of hydrocarbons dispersion. Adaptation and improvement of a state of the art model
(Universitat Politècnica de Catalunya, 2016-10-21)
Tesina
Accés obert -
Monte Carlo methods in electromagnetic scattering computations
(Universitat Politècnica de Catalunya. Remote Sensing, Antennas, Microwaves and Superconductivity Group (CommSensLab), 2022)
Text en actes de congrés
Accés obertThe 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 ... -
Nonlinear propagation effect in x-ray parametric amplification during high harmonic generation
(2022-04-01)
Article
Accés obertWe report the realization and characterization of parametric amplification in high harmonic generation around 100 eV using He gas in a double gas jet arrangement. The delay of the seed extreme ultraviolet (XUV) pulse with ... -
Organic SPC Rework Project
(Universitat Politècnica de Catalunya, 2021-11-01)
Treball Final de Grau
Accés obertThis project has born from the need to be able to use any of the two Hot & Cold mixers presents in the plant of Sant Andreu. The main characteristic of these mixers is that they can encapsulate the pigment (color) inside ... -
Orientación de antenas mediante técnicas fotónicas en sistemas inalámbricos de radiofrecuencia
(Universitat Politècnica de Catalunya, 2018-07)
Treball Final de Grau
Accés obertIn recent years, the orientation of antennas (beamsteering) in wireless communication systems has been influenced by the appearance of 5G networks, which work with a wide bandwidth. The limitations of traditional RF signal ... -
Particle dispersion in two-dimensional turbulence: a comparison with 2-D kinematic simulation
(University of Thechnology and Agriculture Nicholas Copernicus University, 2007-03)
Article
Accés obertWe study numerically the comparison between Lagrangian experiments on turbulent particle dispersion in 2-D turbulent flows performed, on the one hand, on the basis of direct numerical simulations (DNS) and, on the ...