Structural damage detection by fuzzy clustering

The development of strategies for structural health monitoring (SHM) has become increasingly important because of the necessity of preventing undesirable damage. This paper describes an approach to this problem using vibration data. It involves a three-stage process: reduction of the time-series data using principle component analysis (PCA), the development of a data-based model using an auto-regressive moving average (ARMA) model using data from an undamaged structure, and the classification of whether or not the structure is damaged using a fuzzy clustering approach. The approach is applied to data from a benchmark structure from Los Alamos National Laboratory, USA. Two fuzzy clustering algorithms are compared: fuzzy c-means (FCM) and Gustafson-Kessel (GK) algorithms. It is shown that while both fuzzy clustering algorithms are effective, the GK algorithm marginally outperforms the FCM algorithm. (C) 2008 Elsevier Ltd. All rights reserved.

Nonmesonic weak decay spectra of He-4(Lambda)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nonmesonic weak decay of Λ-hypernuclei within independent-particle shell-model

After a short introduction to the nonmesonic weak decay (NMWD) ΛN→nN of Λ-hypernuclei we discuss the long-standing puzzle on the ratio Γn/Γp, and some recent experimental evidences that signalized towards its final solution. Two versions of the Independent-Particle-Shell-Model (IPSM) are employed to account for the nuclear structure of the final residual nuclei. They are: (a) IPSM-a, where no correlation, except for the Pauli principle, is taken into account, and (b) IPSM-b, where the highly excited hole states are considered to be quasi-stationary and are described by Breit-Wigner distributions, whose widths are estimated from the experimental data. We evaluate the coincidence spectra in Λ 4He, Λ 5He, Λ 12C, Λ 16O, and Λ 28Si, as a function of the sum of kinetic energies EnN=En+EN for N=n, p. The recent Brookhaven National Laboratory experiment E788 on Λ 4He, is interpreted within the IPSM. We found that the shapes of all the spectra are basically tailored by the kinematics of the corresponding phase space, depending very weakly on the dynamics, which is gauged here by the one-meson-exchange- potential. In spite of the straightforwardness of the approach a good agreement with data is achieved. This might be an indication that the final-state- interactions and the two-nucleon induced processes are not very important in the decay of this hypernucleus. We have also found that the π+K exchange potential with soft vertex-form-factor cutoffs (Λπ≈0. 7GeV, ΛK≈0.9GeV), is able to account simultaneously for the available experimental data related to Γp and Γn for Λ 4H, and Λ 5He. © 2010 American Institute of Physics.

Redes neurais artificiais artmap-fuzzy aplicadas ao estudo de agitação marítima e ondas de lagos

Pós-graduação em Engenharia Elétrica - FEIS

Colombian results of the interlaboratory quality control exercise 2009 2010

Colombian Reference National Laboratory, GENES LTDA, have organized and coordinated for the past two years (2009 and 2010) the Quality Control Exercise for laboratories undertaking paternity, maternity and forensic tests with DNA markers. Twenty-two laboratories have participated in 2009, increasing the number to 27 in 2010. Laboratories in Colombia, Brazil, Ecuador, Peru, Dominican Republic and Panama have participated in these exercises. There have been some similarities in the two controls: A practical exercise, three blood samples on FTA cards were sent to each participating laboratory to be genotyped for DNA markers using the routine methodologies in their laboratories; theoretical exercises including optional and obligatory cases. For the theoretical exercises, the participating laboratories should calculate the partial and final PI or BRI (Biological Relationship Index or Paternity Index). Forty-nine and 52 markers were under consensus for 2009 and 2010, respectively, distributed in autosomal, Y and X chromosomes STR. With respect to 2008, 12 and 15 additional markers were under consensus for 2009 and 2010, respectively. The rate of reporting error was 2.9% in 2009 while in 2010, 4.7% error was reported. The Proficiency Test conducted through the Colombian National Reference Laboratory has become a useful tool for quality assurance of all Colombian laboratories and some of Latin America that do DNA testing to establish biological relationships and an excellent opportunity for ongoing training of experts from the region.