Browsing by Subject "Mathematical physics"
Now showing items 120 of 43

A onephase Stefan problem with sizedependent thermal conductivity
(20180702)
Article
Open AccessIn this paper a onephase Stefan problem with sizedependent 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 doubleGaussian probability density functions
(20131008)
Article
Open AccessWe introduce a probability density function (PDF)based scheme to parameterize cloud fraction, average liquid water and liquid water flux in largescale models, that is developed from and tested against largeeddy simulations ... 
Assessing the physics of models for transition in pipe flow
(Universitat Politècnica de Catalunya, 20220706)
Bachelor thesis
Open Access
Covenantee: Universität Bremen / Zentrum für angewandte Raumfahrttechnologie und MikrogravitationTransition to turbulence in pipe flow is a long standing problem in the field of turbulence research. In the route to fully turbulent pipe flow, turbulence presents itself in a wide variety of forms. In recent years, a ... 
Controlling chaotic transport in twodimensional periodic potentials
(20101007)
Article
Open AccessWe uncover and characterize different chaotic transport scenarios in perfect twodimensional 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
(20130723)
Article
Open AccessThis 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 largeeddy simulations can ... 
Dynamical sectors for a spinning particle in AdS(3)
(American Physical Society, 20140912)
Article
Open AccessWe 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 ManyBody Quantum Systems
(Universitat Politècnica de Catalunya, 20150703)
Bachelor thesis
Open AccessWe 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 ... 
Eigenvalue curves for generalized MIT bag models
(Springer Nature, 20221122)
Article
Restricted access  publisher's policyWe study spectral properties of Dirac operators on bounded domains O¿R3 with boundary conditions of electrostatic and Lorentz scalar type and which depend on a parameter t¿R; the case t=0 corresponds to the MIT bag model. ... 
Exploration of the internal flux rope current density using a spacecraft constellation
(Universitat Politècnica de Catalunya, 202205)
Bachelor thesis
Open Access
Covenantee: Goddard Space Flight CenterDurant molts anys la comunitat científica ha estat treballant per entendre millor la topologia i les propietats físiques dels tubs de flux (flux ropes en anglès), car són una de les principals formes en les quals l’activitat ... 
Factorization of the Fourier transform of the pressurePoisson equation using finite differences in colocated grids
(WileyVCH, 20120229)
Article
Open AccessThe zerodivergence constraint on the velocity field in the numerical simulation of incompressible flows can be reduced, in certain cases, to a set of onedimensional linear difference equations for the pressure. These ... 
Geometric HamiltonJacobi theory for higherorder autonomous systems
(20130909)
Research report
Open AccessThe geometric framework for the HamiltonJacobi theory is used to study this theory in the ambient of higherorder mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding ... 
Geometric Quantization of real polarizations via sheaves
(201301)
Research report
Open AccessIn 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 ... 
Global analysis of direct transfers from lunar orbits to sunearth libration point regimes
(Springer Nature, 20210401)
Article
Open AccessIn this paper we look forward to obtain a global picture of simple transfer opportunities from Lunar to SunEarth libration orbits, useful for a preliminary design of these mission scenarios. Considering the trajectory of ... 
Gravitational Particle Production in Massive Chaotic Inflation and the Moduli Problem
(201202)
Article
Restricted access  publisher's policyParticle 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
(2014)
Article
Restricted access  publisher's policyWe prove a Faà di Bruno formula for the Green function in the bialgebra of Ptrees, 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
(201207)
Research report
Open AccessWe prove a Faa di Bruno formula for the Green function in the bialgebra of Ptrees, for any polynomial endofunctor P. The formula appears as relative homotopy cardinality of an equivalence of groupoids. For suitable choices ... 
Heterogenous meanfield analysis of a generalized voterlike model on networks
(Springer, 201203)
Article
Open AccessWe propose a generalized framework for the study of voter models in complex networks at the heterogeneous meanfield (HMF) level that (i) yields a unified picture for existing copy/invasion processes and (ii) allows for ... 
High order dynamical systems approaches for lowthrust stationkeeping of libration point orbits
(20220101)
Article
Restricted access  publisher's policyWe derive two families of lowthrust stationkeeping control procedures based on the dynamical properties of the phase space near libration point orbits. The first family is obtained as the limit of impulsive maneuvers, ... 
Higherorder mechanics: variational principles and other topics
(American Institute of Mathematical Sciences, 201312)
Article
Open AccessAfter reviewing the LagrangianHamiltonian unified formalism (i.e, the SkinnerRusk formalism) for higherorder (nonautonomous) dynamical systems, we state a unified geometrical version of the Variational Principles which ... 
Infinitesimal time reparametrisation and its applications
(Springer, 20220221)
Article
Open AccessA geometric approach to Sundman infnitesimal timereparametrisation is given and some of its applications are used to illustrate the general theory. Special emphasis is put on geodesic motions and systems described by ...