A probabilistic model for elastic-plastic fracture analysis of plane and axisymmetric structures

This work presents a methodology for elastic-plastic fracture reliability analysis of plane and axisymmetric structures. The structural reliability analysis is accomplished by means of the FORM analytical method. The virtual crack extension technique based on a direct minimization of potencial energy is utililized for the calculation of the energy release rate. Results are presented to illustrate the performance of the adopted methodology.

Simulation and analysis of a collisionless optical interconnection network

This article describes the simulation and analysis of collisionless optical interconnection network, which the objective is to achieve a high performance level based on a single protocol control. The optical coupler has one shared control channel and N communication channels. Each network node two communication modules one for packet transmission/reception and another for control channel access. We show by simulation that system achieves a high performance and ensures high scalability.

Analysis of heuristic algorithms for the transportation model in static and multistage planning in network expansion systems

The usefulness of the application of heuristic algorithms in the transportation model, first proposed by Garver, is analysed in relation to planning for the expansion of transmission systems. The formulation of the mathematical model and the solution techniques proposed in the specialised literature are analysed in detail. Starting with the constructive heuristic algorithm proposed by Garver, an extension is made to the problem of multistage planning for transmission systems. The quality of the solutions found by heuristic algorithms for the transportation model is analysed, as are applications in problems of planning transmission systems.

On a regular convex solver potential for an elastic-damage constitutive model: a theoretical analysis

This work is related with the proposition of a so-called regular or convex solver potential to be used in numerical simulations involving a certain class of constitutive elastic-damage models. All the mathematical aspects involved are based on convex analysis, which is employed aiming a consistent variational formulation of the potential and its conjugate one. It is shown that the constitutive relations for the class of damage models here considered can be derived from the solver potentials by means of sub-differentials sets. The optimality conditions of the resulting minimisation problem represent in particular a linear complementarity problem. Finally, a simple example is present in order to illustrate the possible integration errors that can be generated when finite step analysis is performed. (C) 2003 Elsevier Ltd. All rights reserved.

Quantitative analysis of mineral content in enamel using synchrotron microtomography and microhardness analysis. - art. no. 631824

Synchrotron microtomography is a tool to quantify the mineralization of dental tissues as well as microhardness analysis, since they provide adequate precision and contrast sensitivity. This study evaluates synchrotron microtomography and microhardness analysis for quantifying the mineral content of bovine enamel. Fifty enamel blocks were submitted individually for 5 days to a pH-cycling model at 37 degrees C and remained in the remineralizing solution for 2 days. The blocks were treated twice daily for 1 min with NaF dentifrices (Placebo, 275, 550, 1,100 mu g F/g and Crest (R)) diluted in deionized water. Surface microhardness changes (%SMH) and mineral loss (Delta Z) were then calculated. Synchrotron microtomography was also used to measure total mineral lost (SMM). Pearson's correlation (p < 0.05) was used to determine the relationship between different methods of analysis and dose-response between treatments. Dentifrice fluoride concentration and %SMH and Delta Z were correlated (p < 0.05). There was a positive relationship (p < 0.05) when comparing SMM vs. Delta Z; a negative relationship (p < 0.05) was found for %SMH vs. SMM and %SMH vs. Delta Z. Based on the results of this study, it was possible to conclude that synchrotron microtomography provides the best spatial resolution and contrast sensitivity for quantifying mineral gradients.

Agent-based model to rural-urban migration analysis

In this paper, we analyze the rural-urban migration phenomenon as it is usually observed in economies which are in the early stages of industrialization. The analysis is conducted by means of a statistical mechanics approach which builds a computational agent-based model. Agents are placed on a lattice and the connections among them are described via an Ising-like model. Simulations on this computational model show some emergent properties that are common in developing economies, such as a transitional dynamics characterized by continuous growth of urban population, followed by the equalization of expected wages between rural and urban sectors (Harris-Todaro equilibrium condition), urban concentration and increasing of per capita income. (c) 2005 Elsevier B.V. All rights reserved.

Analysis of cement slurries by inductively coupled plasma optical emission spectrometry with axial viewing

The feasibility of Portland cement analysis by introduction of slurries in an inductively coupled plasma optical emission spectrometer (ICP-OES) with axial viewing has been evaluated. After a fast manual grinding of the cement samples, owing to the pulverized state of this material, 0.1% m/v slurries were prepared in 1% v/v HCl. The calibration was performed adopting two strategies: one based on slurries prepared from different masses (50, 75, 100 and 125 mg) of a Portland cement standard reference material (NIST SRM 1881), and the other one based on aqueous reference solutions. A complete analysis of cement for major (Al, Ca, Fe, Mg and Si), minor and trace elements (Mn, P, S, Sr and Ti) was accomplished. Both strategies led to accurate results for commercial Portland cement samples, except for Si and Ti. for which the calibration with aqueous reference solutions resulted in low values. Applying a paired t-test it was shown that most results were in agreement at a 95% confidence level with a conventional fusion decomposition procedure. The ICP-OES with axial viewing and end-on gas configuration for removal of the recombination plasma zone was effective for cement slurry analysis without any undesirable particle deposition in the pre-optics interface and without severe spectral interferences. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Glucose reactivity with filling materials as a limitation for using the glucose leakage model

Aim To evaluate the reactivity of different endodontic materials and sealers with glucose and to asses the reliability of the glucose leakage model in measuring penetration of glucose through these materials.Methodology Ten uniform discs (radius 5 mm, thickness 2 mm) were made of each of the following materials: Portland cement, MTA (grey and white), sealer 26, calcium sulphate, calcium hydroxide [Ca(OH)(2)], AH26,Epiphany, Resilon, gutta-percha and dentine. After storing the discs for 1 week at 37 degrees C and humid conditions, they were immersed in 0.2 mg mL(-1) glucose solution in a test tube. The concentration of glucose was evaluated using an enzymatic reaction after 1 week. Statistical analysis was performed with the ANOVA and Dunnett tests at a significant level of P < 0.05.Results Portland cement, MTA, Ca(OH)(2) and sealer 26 reduced the concentration in the test tube of glucose significantly after 1 week (P < 0.05). Calcium sulphate reduced the concentration of glucose, but the difference in concentrations was not significant (P = 0.054).Conclusions Portland cement, MTA, Ca(OH)(2) and sealer 26 react with a 0.2 mg mL(-1) glucose solution. Therefore, these materials should not be evaluated for sealing ability with the glucose leakage model.

On-line redox speciation analysis of antimony using L-proline immobilized on controlled pore glass and hydride generation inductively coupled plasma optical emission spectrometry for detection

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

Genetic correlations between categorical morphological traits in Nelore cattle by applying Bayesian analysis under a threshold animal model

P>In this study, Bayesian analysis under a threshold animal model was used to estimate genetic correlations between morphological traits (body structure, finishing precocity and muscling) in Nelore cattle evaluated at weaning and yearling. Visual scores obtained from 7651 Nelore cattle at weaning and from 4155 animals at yearling, belonging to the Brazilian Nelore Program, were used. Genetic parameters for the morphological traits were estimated by two-trait Bayesian analysis under a threshold animal model. The genetic correlations between the morphological traits evaluated at two ages of the animal (weaning and yearling) were positive and high for body structure (0.91), finishing precocity (0.96) and muscling (0.94). These results indicate that the traits are mainly determined by the same set of genes of additive action and that direct selection at weaning will also result in genetic progress for the same traits at yearling. Thus, selection of the best genotypes during only one phase of life of the animal is suggested. However, genetic differences between morphological traits were better detected during the growth phase to yearling. Direct selection for body structure, finishing precocity and muscling at only one age, preferentially at yearling, is recommended as genetic differences between traits can be detected at this age.

Near-infrared Raman spectroscopy to detect anti-Toxoplasma gondii antibody in blood sera of domestic cats: quantitative analysis based on partial least-squares multivariate statistics

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

A Bayesian Analysis of Spectral ARMA Model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Finite element analysis of anisotropic optical waveguide with arbitrary index profile

This work presents the application of a scalar finite element formulation for Ex (TE-like) modes in anisotropic planar and channel waveguides with diagonal permittivity tensor, diffused in both transversal directions. This extended formulation considers explicitly both the variations of the refractive index and their spatial derivates inside of each finite element. Dispersion curves for Ex modes in planar and channel waveguides are shown, and the results compared with solutions obtained by other formulations.

Conceptual model for adaptable and extensible visual data exploration

Interactive visual representations complement traditional statistical and machine learning techniques for data analysis, allowing users to play a more active role in a knowledge discovery process and making the whole process more understandable. Though visual representations are applicable to several stages of the knowledge discovery process, a common use of visualization is in the initial stages to explore and organize a sometimes unknown and complex data set. In this context, the integrated and coordinated - that is, user actions should be capable of affecting multiple visualizations when desired - use of multiple graphical representations allows data to be observed from several perspectives and offers richer information than isolated representations. In this paper we propose an underlying model for an extensible and adaptable environment that allows independently developed visualization components to be gradually integrated into a user configured knowledge discovery application. Because a major requirement when using multiple visual techniques is the ability to link amongst them, so that user actions executed on a representation propagate to others if desired, the model also allows runtime configuration of coordinated user actions over different visual representations. We illustrate how this environment is being used to assist data exploration and organization in a climate classification problem.

Fluorescence spectroscopy for tongue carcinoma detection: Study in an animal model

Fluorescence diagnosis of malignant lesions has been showed as an attractive optical technique due especially to its real-time response and a more objective and quantitative evaluation. Even though the oral cavity allows a direct examination many lesions are diagnosed when it is already in advanced stage, compromising the patient prognosis. In this study, the fluorescence spectroscopy was used to the detection of chemically induced carcinoma at the lateral border of the tongue in a hamster model. Two excitations wavelengths in visible region were applied: 442 and 532 nm. All the spectra results were analyzed comparing with the histopathological diagnosis. The better results were achieved with the 442 nm laser excitation. The spectra from carcinoma showed new emission bands and these were used to determined different ratios for a quantitative analysis. Using the 625-645 nm fluorescence range under 442 nm excitation (A3 coefficient) the percentage of false negative was of 9.1%, however the false positive percentage was of 18.5%. The 532 nm excitation provided a better normal tissue detection compared to 442 nm excitation. The ideal clinical condition is probably the use of multiple wavelengths excitation for a broader tissue fluorescence investigation.