arXiv subjects

Giovani L. Vasconcelos

Publications and source records attributed to Giovani L. Vasconcelos.

24 records · Page 2Linked to original sources

arXiv2010

Doubly-periodic array of bubbles in a Hele-Shaw cell

Exact solutions are presented for a doubly-periodic array of steadily moving bubbles in a Hele-Shaw cell when surface tension is neglected. It is assumed that the bubbles either are symmetrical with respect to the channel centreline or have fore-and-aft symmetry, or both, so that the relevant flow domain can be reduced to a simply connected region. By using conformal mapping techniques, a general solution with any number of bubbles per unit cell is obtained in integral form. Several examples are given, including solutions for multi-file arrays of bubbles in the channel geometry and doubly-periodic solutions in an unbounded cell.

physics.flu-dyn↗

arXiv2010

Interface growth in two dimensions: A Loewner-equation approach

The problem of Laplacian growth in two dimensions is considered within the Loewner-equation framework. Initially the problem of fingered growth recently discussed by Gubiec and Szymczak [T. Gubiec and P. Szymczak, Phys. Rev. E 77, 041602 (2008)] is revisited and a new exact solution for a three-finger configuration is reported. Then a general class of growth models for an interface growing in the upper-half plane is introduced and the corresponding Loewner equation for the problem is derived. Several examples are given including interfaces with one or more tips as well as multiple growing interfaces. A generalization of our interface growth model in terms of ``Loewner domains,'' where the growth rule is specified by a time evolving measure, is briefly discussed.

cond-mat.stat-mech↗

arXiv2007

Correlations between political party size and voter memory: A statistical analysis of opinion polls

This paper describes the application of statistical methods to political polling data in order to look for correlations and memory effects. We propose measures for quantifying the political memory using the correlation function and scaling analysis. These methods reveal time correlations and self-affine scaling properties respectively, and they have been applied to polling data from Norway. Power-law dependencies have been found between correlation measures and party size, and different scaling behaviour has been found for large and small parties.

physics.soc-ph↗

arXiv2006

Optimized suppression of coherent noise from seismic data using the Karhunen-Loeve transform

Signals obtained in land seismic surveys are usually contaminated with coherent noise, among which the ground roll (Rayleigh surface waves) is of major concern for it can severely degrade the quality of the information obtained from the seismic record. Properly suppressing the ground roll from seismic data is not only of great practical importance but also remains a scientific challenge. Here we propose an optimized filter based on the Karhunen--Loéve transform for processing seismic data contaminated with ground roll. In our method, the contaminated region of the seismic record, to be processed by the filter, is selected in such way so as to correspond to the maximum of a properly defined coherence index. The main advantages of the method are that the ground roll is suppressed with negligible distortion of the remanent reflection signals and that the filtering can be performed on the computer in a largely unsupervised manner. The method has been devised to filter seismic data, however it could also be relevant for other applications where localized coherent structures, embedded in a complex spatiotemporal dynamics, need to be identified in a more refined way.

nlin.PS↗

arXiv2004

A Guided Walk Down Wall Street: an Introduction to Econophysics

This article contains the lecture notes for the short course ``Introduction to Econophysics,'' delivered at the II Brazilian School on Statistical Mechanics, held in Sao Carlos, Brazil, in February 2004. The main goal of the present notes is twofold: i) to provide a brief introduction to the problem of pricing financial derivatives in continuous time; and ii) to review some of the related problems to which physicists have made relevant contributions in recent years.

cond-mat.other↗

arXiv1999

Geometrical model for a particle on a rough inclined surface

A simple geometrical model is presented for the gravity-driven motion of a single particle on a rough inclined surface. Adopting a simple restitution law for the collisions between the particle and the surface, we arrive at a model in which the dynamics is described by a one-dimensional map. This map is studied in detail and it is shown to exhibit several dynamical regimes (steady state, chaotic behavior, and accelerated motion) as the model parameters vary. A phase diagram showing the corresponding domain of existence for these regimes is presented. The model is also found to be in good qualitative agreement with recent experiments on a ball moving on a rough inclined line.

cond-mat.soft↗