Exploració per tema "Instability"
Ara es mostren els items 1-20 de 20
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A general mechanism of instability in Hamiltonian systems: skipping along a normally hyperbolic invariant manifold
(2020)
Article
Accés obertWe describe a recent method to show instability in Hamiltonian systems. The main hypothesis of the method is that some explicit transversality conditions – which can be verified in concrete systems by finite calculations ... -
A mechanism for streamwise localisation of nonlinear waves in shear flows
(2015-09-01)
Article
Accés obertWe present the complete unfolding of streamwise localisation in a paradigm of extended shear flows, namely two-dimensional plane Poiseuille flow. Exact solutions of the Navier-Stokes equations are computed numerically and ... -
Abolladura de estructuras de barras de sección tipo doble-T
(Universitat Politècnica de Catalunya. CIMNE, 2017)
Article
Accés obertEn este trabajo se expone una metodología de varias etapas para determinar, con mínimo esfuerzo computacional el factor de carga crítico que produce el fenómeno de inestabilidad local de abolladura de las paredes de los ... -
Abolladura de estructuras de barras de sección tipo doble-T
(Universitat Politècnica de Catalunya. CIMNE, 2017)
Article
Accés obertEn este trabajo se expone una metodología de varias etapas para determinar, con mínimo esfuerzo computacional el factor de carga crítico que produce el fenómeno de inestabilidad local de abolladura de las paredes de los ... -
Arrow-shaped elasto-inertial rotating waves
(Royal Society, 2023-05-01)
Article
Accés obertWe present direct numerical simulations of the Taylor–Couette flow of a dilute polymer solution when only the inner cylinder rotates and the curvature of the system is moderate (¿=0.77 ). The finitely extensible nonlinear ... -
Conmutación temporal entre técnicas numéricas implícita y explícita para simulación de estructuras no lineales inestables
(Universitat Politècnica de Catalunya. CIMNE, 2013)
Article
Accés obertEl problema de la simulación de materiales no lineales sujetos a inestabilidad estructural implica en numerosos casos la divergencia de métodos implícitos que usan algoritmos de retorno para la simulación del comportamiento ... -
Hydromechanical behaviour of a silty sand from a steep slope triggered by artificial rainfall : from unsaturated to saturated conditions
(2013-01)
Article
Accés restringit per política de l'editorialThis paper presents an experimental investigation aimed at studying the hydromechanical behaviour of a silty sand from a steep slope in Ruedlingen in the northeast of Switzerland, where a landslide-triggering experiment ... -
Instabilities in digitally controlled voltage-mode synchronous buck converter
(2012)
Article
Accés restringit per política de l'editorialIn this paper, instabilities and bifurcation behavior in a DC–DC digitally controlled voltagemode synchronous buck converter (SBC) are studied. The bifurcation diagram of the system under a proportional-integral (PI) ... -
Instability of high dimensional Hamiltonian systems: Multiple resonances do not impede diffusion
(2016-05-14)
Article
Accés obertWe consider models given by Hamiltonians of the form View the MathML sourceH(I,f,p,q,t;e)=h(I)+¿j=1n±(12pj2+Vj(qj))+eQ(I,f,p,q,t;e) Turn MathJax on where I¿I¿Rd,f¿TdI¿I¿Rd,f¿Td, p,q¿Rnp,q¿Rn, t¿T1t¿T1. These are higher ... -
Logarithmic convexity for third order in time partial differential equations
(2023-08)
Article
Accés obertIn this short note, we want to describe the logarithmic convexity argument for third-order in time partial differential equations. As a consequence, we first prove a uniqueness result whenever certain conditions on the ... -
Numerical and experimental research in tapered steel plate girders subjected to shear
(2010)
Text en actes de congrés
Accés obert -
On a theory of thermoelastic materials with double porosity structure
(2014-10-01)
Article
Accés obertIn this article, we use the Nunziato–Cowin theory of materials with voids to derive a theory of thermoelastic solids, which have a double porosity structure. The new theory is not based on Darcy's law. In the case of ... -
On the instability for an incremental problem in elastodynamics
(Elsevier, 2022-09)
Article
Accés obertIn this short note, we consider some issues regarding the instability of some elastodynamical problems when the elasticity tensor is not positive definite. By using the so-called logarithmic convexity argument, we prove ... -
On the instability, nonexistence and spatial behaviour of the one-dimensional response of a new class of elastic bodies
(2021-05-22)
Article
Accés obertIn this note we consider 1D problems within the context of a new class of elastic bodies. Under suitable conditions on the constitutive equations we prove instability and nonexistence of solutions similar to those in place ... -
On the stability in phase-lag heat conduction with two temperatures
(2018-06-15)
Article
Accés obertWe investigate the well-posedness and the stability of the solutions for several Taylor approximations of the phase-lag two-temperature equations.We give conditions on the parameters which guarantee the existence and ... -
On uniqueness and instability for some thermomechanical problems involving the Moore– Gibson–Thompson equation
(2020-06)
Article
Accés obertIt is known that in the case that several constitutive tensors fail to be positive definite the system of the ther- moelasticity could become unstable and, in certain cases, ill-posed in the sense of Hadamard. In this ... -
On uniqueness and stability for a thermoelastic theory
(2017-06)
Article
Accés obertIn this paper we investigate a thermoelastic theory obtained from the Taylor approximation for the heat flux vector proposed by Choudhuri. This new thermoelastic theory gives rise to interesting mathematical questions. We ... -
Precession of a rapidly rotating cylinder flow: traverse through resonance
(2015-10-06)
Article
Accés restringit per política de l'editorialRecent experiments using a rapidly rotating and precessing cylinder have shown that for specific values of the precession rate, aspect ratio and tilt angle, sudden catastrophic transitions to turbulence occur. Even if the ... -
Spontaneous generation of a swirling plume in a stratified ambient
(2014-12-01)
Article
Accés restringit per política de l'editorialThe transition from laminar to complex spatio-temporal dynamics of plumes due to a localized buoyancy source is studied numerically. Several experiments have reported that this transition is sensitive to external perturbations. ... -
Structure of force variability during squats performed with an inertial flywheel device under stable versus unstable surfaces
(2019-08)
Article
Accés obertThe use of unstable surfaces during resistance training has demonstrated a maintenance or reduction on force production. However, the use of unstable surface on force variability has not been assessed using non-linear ...