Search results for "Discrete"

Enhancing Metastability by Dissipation and Driving in an Asymmetric Bistable Quantum System.

2018

The stabilizing effect of quantum fluctuations on the escape process and the relaxation dynamics from a quantum metastable state are investigated. Specifically, the quantum dynamics of a multilevel bistable system coupled to a bosonic Ohmic thermal bath in strong dissipation regime is analyzed. The study is performed by a non-perturbative method based on the real-time path integral approach of the Feynman-Vernon influence functional. We consider a strongly asymmetric double well potential with and without a monochromatic external driving, and with an out-of-equilibrium initial condition. In the absence of driving we observe a nonmonotonic behavior of the escape time from the metastable regi…

Trend of inter-arrival times of rainfall events for Italian Sub-Alpine and Mediterranean areas

2011

Generalized wave propagation problems and discrete exterior calculus

2018

We introduce a general class of second-order boundary value problems unifying application areas such as acoustics, electromagnetism, elastodynamics, quantum mechanics, and so on, into a single framework. This also enables us to solve wave propagation problems very efficiently with a single software system. The solution method precisely follows the conservation laws in finite-dimensional systems, whereas the constitutive relations are imposed approximately. We employ discrete exterior calculus for the spatial discretization, use natural crystal structures for three-dimensional meshing, and derive a “discrete Hodge” adapted to harmonic wave. The numerical experiments indicate that the cumulat…

Mappings of Lp-integrable distortion: regularity of the inverse

2016

Let be an open set in ℝn and suppose that is a Sobolev homeomorphism. We study the regularity of f–1 under the Lp-integrability assumption on the distortion function Kf. First, if is the unit ball and p > n – 1, then the optimal local modulus of continuity of f–1 is attained by a radially symmetric mapping. We show that this is not the case when p ⩽ n – 1 and n ⩾ 3, and answer a question raised by S. Hencl and P. Koskela. Second, we obtain the optimal integrability results for ∣Df–1∣ in terms of the Lp-integrability assumptions of Kf.

Rocking behaviour of multi-block columns subjected to pulse-typeground motion accelerations

2016

Ancient columns, made with a variety of materials such as marble, granite, stone or masonry are an important part of theEuropean cultural heritage. In particular columns of ancient temples in Greece and Sicily which support only the architrave arecharacterized by small axial load values. This feature together with the slenderness typical of these structural members clearlyhighlights as the evaluation of the rocking behaviour is a key aspect of their safety assessment and maintenance. It has to be notedthat the rocking response of rectangular cross-sectional columns modelled as monolithic rigid elements, has been widely investigatedsince the first theoretical study carried out by Housner (19…

The Joint Distribution Criterion and the Distance Tests for Selective Probabilistic Causality

2010

A general definition and a criterion (a necessary and sufficient condition) are formulated for an arbitrary set of external factors to selectively influence a corresponding set of random entities (generalized random variables, with values in arbitrary observation spaces), jointly distributed at every treatment (a set of factor values containing precisely one value of each factor). The random entities are selectively influenced by the corresponding factors if and only if the following condition, called the joint distribution criterion, is satisfied : there is a jointly distributed set of random entities, one entity for every value of every factor, such that every subset of this set that corr…

Quantum walks: background geometry and gauge invariance

2019

Ciertos tipos de problemas no pueden resolverse usando los actuales ordenadores clásicos. Una forma de encontrar una solución, es mediante el uso de ordenadores cuánticos. Sin embargo, construir un ordenador cuántico es realmente complicado actualmente, debido a las limitaciones tecnológicas. Mientras tanto, los simuladores cuánticos han sido capaces de resolver algunos de estos problemas, ya que los simuladores cuánticos son más accesibles experimentalmente. Las llamadas caminatas cuánticas, en su versión discreta, son una herramienta muy útil para simular ciertos sistemas físicos. En el límite al continuo, se puede obtener una serie de ecuaciones diferenciales, particularmente, la ecuació…

Highmann's Theorem on Discrete Sets

2006

In this paper we investigate properties of different classes of discrete sets with respect to the partial-order of subpicture. In particular we take in consideration the classes of convex polyominoes and L-convex polyominoes. In the first part of the paper we study closure properties of these classes with respect the order and we give a new characterization of L-convex polyominoes. In the second part we pose the question to extend Higman’s theoremto discrete sets. We give a negative answer in the general case and we prove that the set of L-convex polyominoes is well-partially-ordered by using a representation of L-convex polyominoes in terms of words of a regular language.

The Homogeneous Poisson Point Process

2008

Openness and Discreteness

2013

The aim of this chapter is to study conditions under which a mapping of finite distortion is open (maps open sets to open sets) and discrete (preimage of each point is a discrete set).