Now showing items 1-20 of 32

    • A one-phase Stefan problem with size-dependent thermal conductivity 

      Font Martínez, Francesc (2018-07-02)
      Article
      Open Access
      In this paper a one-phase Stefan problem with size-dependent thermal conductivity is analysed. Approximate solutions to the problem are found via perturbation and numerical methods, and compared to the Neumann solution for ...
    • A refined statistical cloud closure using double-Gaussian probability density functions 

      Naumann, Ann Kristin; Seifert, Alex; Mellado González, Juan Pedro (2013-10-08)
      Article
      Open Access
      We introduce a probability density function (PDF)-based scheme to parameterize cloud fraction, average liquid water and liquid water flux in large-scale models, that is developed from and tested against large-eddy simulations ...
    • Controlling chaotic transport in two-dimensional periodic potentials 

      Chacon, R.; Lacasta Palacio, Ana María (2010-10-07)
      Article
      Open Access
      We uncover and characterize different chaotic transport scenarios in perfect two-dimensional periodic potentials by controlling the chaotic dynamics of particles subjected to periodic external forces in the absence of a ...
    • Direct Numerical Simulation of evaporative cooling at the lateral boundary of shallow cumulus clouds 

      Abma, Dick; Heus, Thijs; Mellado González, Juan Pedro (2013-07-23)
      Article
      Open Access
      This study investigates the dynamics of the subsiding shell at the lateral boundary of cumulus clouds, focusing on the role of evaporative cooling. Since the size of this shell is well below what large-eddy simulations can ...
    • Dynamical sectors for a spinning particle in AdS(3) 

      Batlle Arnau, Carles; Gomis, Jaoquim; Kamimura, kiyoshi; Zanelli, Jorge (American Physical Society, 2014-09-12)
      Article
      Open Access
      We consider the dynamics of a particle of mass M and spin J in AdS(3). The study reveals the presence of different dynamical sectors depending on the relative values of M, J and the AdS(3) radius R. For the subcritical ...
    • Dynamics of Many-Body Quantum Systems 

      Giménez Grau, Aleix (Universitat Politècnica de Catalunya, 2015-07-03)
      Bachelor thesis
      Open Access
      We study the ground state and the excitations of quantum bose systems. The hypernetted chain equations (HNC) are introduced and we show that the methods based on them produce acceptable approximations of the static structure ...
    • Factorization of the Fourier transform of the pressure-Poisson equation using finite differences in colocated grids 

      Mellado González, Juan Pedro; Ansorge, Cedrick (Wiley-VCH, 2012-02-29)
      Article
      Open Access
      The zero-divergence constraint on the velocity field in the numerical simulation of incompressible flows can be reduced, in certain cases, to a set of one-dimensional linear difference equations for the pressure. These ...
    • Geometric Hamilton-Jacobi theory for higher-order autonomous systems 

      Colombo, Leonardo; de León, Manuel; Prieto Martínez, Pedro Daniel; Román Roy, Narciso (2013-09-09)
      External research report
      Open Access
      The geometric framework for the Hamilton-Jacobi theory is used to study this theory in the ambient of higher-order mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding ...
    • Geometric Quantization of real polarizations via sheaves 

      Miranda Galcerán, Eva; Presas, Francisco (2013-01)
      External research report
      Open Access
      In this article we develop tools to compute the Geometric Quantization of a symplectic manifold with respect to a regular Lagrangian foliation via sheaf cohomology. The starting point is the definition of representation ...
    • Gravitational Particle Production in Massive Chaotic Inflation and the Moduli Problem 

      Haro Cases, Jaume; Elizalde, Emilio (2012-02)
      Article
      Restricted access - publisher's policy
      Particle production from vacuum fluctuations during inflation is briefly revisited. The moduli problem occurring with light particles produced at the end of inflation is addressed, namely the fact that some results are in ...
    • Groupoids and Faà di Bruno formulae for Green functions in bialgebras of trees 

      Gálvez Carrillo, Maria Immaculada; Kock, Joachim; Tonks, Andrew (2014)
      Article
      Restricted access - publisher's policy
      We prove a Faà di Bruno formula for the Green function in the bialgebra of P-trees, for any polynomial endofunctor P. The formula appears as relative homotopy cardinality of an equivalence of groupoids.
    • Groupoids and Faà di Bruno Formulae for green functions in bialgebras of trees 

      Gálvez Carrillo, Maria Immaculada; Tonks, Andrew; Kock, Joachim (2012-07)
      External research report
      Open Access
      We prove a Faa di Bruno formula for the Green function in the bialgebra of P-trees, for any polynomial endofunctor P. The formula appears as relative homotopy cardinality of an equivalence of groupoids. For suitable choices ...
    • Heterogenous mean-field analysis of a generalized voter-like model on networks 

      Moretti, Paolo; Liu, S.Y.; Baronchelli, Andrea; Pastor Satorras, Romualdo (Springer, 2012-03)
      Article
      Open Access
      We propose a generalized framework for the study of voter models in complex networks at the heterogeneous mean-field (HMF) level that (i) yields a unified picture for existing copy/invasion processes and (ii) allows for ...
    • Higher-order mechanics: variational principles and other topics 

      Prieto Martínez, Pedro Daniel; Román Roy, Narciso (American Institute of Mathematical Sciences, 2013-12)
      Article
      Open Access
      After reviewing the Lagrangian-Hamiltonian unified formalism (i.e, the Skinner-Rusk formalism) for higher-order (non-autonomous) dynamical systems, we state a unified geometrical version of the Variational Principles which ...
    • Microscopic modelling of the optical properties of 2D perovskites 

      Feldstein Bofill, David (Universitat Politècnica de Catalunya, 2020-06)
      Bachelor thesis
      12 months embargo
      Covenantee:   Chalmers tekniska högskola
      This work focuses on the optical properties of a quasi-two-dimensional perovskite. Using the quantum formalism based on the density matrix and the second quantization operators we obtain mathematical expressions for ...
    • Modelling shoreface-connected sand ridges observed at the inner shelf of the Ebro delta 

      Tugores Rorbek, Francisco (Universitat Politècnica de Catalunya, 2018-06)
      Bachelor thesis
      Open Access
      The large amount of sand provided by coastal erosion in the river mouth and the combination between high-speed currents induced by Mistral wind and severe wave-storm events might have been the favourable conditions in the ...
    • On the calculation of the D-optimal multisine excitation power spectrum for broadband impedance spectroscopy measurements 

      Sánchez Terrones, Benjamín; Rojas, C.R.; Vandersteen, G.; Bragós Bardia, Ramon; Schoukens, J. (2012-08)
      Article
      Open Access
      The successful application of impedance spectroscopy in daily practice requires accurate measurements for modeling complex physiological or electrochemical phenomena in a single frequency or several frequencies at different ...
    • Quantum corrections in nanoplasmonics & deep neural network training with reverse supervision 

      Gómez Iñesta, Álvaro (Universitat Politècnica de Catalunya, 2018-05)
      Bachelor thesis
      Open Access
      Covenantee:   Massachusetts Institute of Technology
      The classical theory of plasmonics fails dramatically at geometric length scales below 30 nm, due to quantum phenomena like electronic spill-out of the wave function, nonlocality and Landau damping. An alternative to the ...
    • Rigidity of infinitesimal momentum maps 

      Miranda Galcerán, Eva; Esposito, Chiara (2016)
      Article
      Open Access
      In this paper we prove rigidity theorems for Poisson Lie group actions on Poisson manifolds. In particular, we prove that close infinitesimal momentum maps associated to Poisson Lie group actions are equivalent using a ...
    • Shortcuts to adiabaticity for the transport of matter waves 

      Rasmita, Abdullah (Universitat Politècnica de Catalunya / Universitat Autònoma de Barcelona, 2013-09-10)
      Master thesis
      Open Access
      [ANGLES] In this master thesis we investigate the quantum transport of a single neutral atom between double-well and triple-well potentials. In particular, we study and implement the Fast-Forward technique to speed up the ...