Fractal analysis of weld defect patterns obtained by radiographic tests (2006)
Tesser, J. A., Lopes, R. T., Vieira, A. P., Goncalves, L. L., Rebello, J. M. A.
This paper presents a fractal analysis of radiographic patterns obtained from specimens with three types of inserted welding defects: lack of fusion, lack of penetration, and porosity. The study...
Characterization of welding defects by fractal analysis of ultrasonic signals (2006)
Vieira, A. P., De Moura, E. P., Goncalves, L. L., Rebello, J. M. A.
In this work we apply tools developed for the study of fractal properties of time series to the problem of classifying defects in welding joints probed by ultrasonic tecniques. We employ the fractal...
Phase diagrams of soluble multi-spin glass models (2005)
Muzy, P. T., Vieira, A. P., Salinas, S. R.
We include p-spin interactions in a spherical version of a soluble mean-field spin-glass model proposed by van Hemmen. Due to the simplicity of the solutions, which do not require the use of the...
Lymphadenopathy after BCG vaccination in a child with chronic granulomatous disease (2004)
Vieira, A.P., Vasconcelos, J., Fernandes, J.C., Antunes, H., Basto, S., Macedo, C., ...
We present a phenomenological model for the remanent magnetization at low temperatures in the quasi-one-dimensional dilute antiferromagnets CH_{3}NH_{3}Mn_{1-x}Cd_{x} Cl_{3}\cdot 2H_{2}O and...
Correlated disordered interactions on Potts models (2002)
Muzy, P. T., Vieira, A. P., Salinas, S. R.
Using a weak-disorder scheme and real-space renormalization-group techniques, we obtain analytical results for the critical behavior of various q-state Potts models with correlated disordered...
Phase diagram of a random-anisotropy mixed-spin Ising model (2001)
Vieira, A. P., De Carvalho, J. X., Salinas, S. R.
We investigate the phase diagram of a mixed spin-1/2--spin-1 Ising system in the presence of quenched disordered anisotropy. We carry out a mean-field and a standard self-consistent Bethe--Peierls...
The one-dimensional XXZ model with long-range interactions (2000)
Goncalves, L. L., Vieira, A. P., Coutinho, L. P. S.
The one-dimensional XXZ model (s=1/2, N sites) with uniform long-range interactions among the transverse components of the spins is considered. The Hamiltonian of the model is explicitly given by...
Phase diagram of random lattice gases in the annealed limit (1998)
Vieira, A. P., Goncalves, L. L.
An analysis of the random lattice gas in the annealed limit is presented. The statistical mechanics of disordered lattice systems is briefly reviewed. For the case of the lattice gas with an...
One-dimensional Ising model with long-range and random short-range interactions (1998)
Vieira, A. P., Goncalves, L. L.
The one-dimensional Ising model in an external magnetic field with uniform long-range interactions and random short-range interactions satisfying bimodal annealed distributions is studied. This...