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Morais T.S.,Federal University of Uberlndia | Steffen Jr. V.,Federal University of Uberlndia | Mahfoud J.,INSA Lyon
Latin American Journal of Solids and Structures | Year: 2012

This paper presents a numerical study devoted to the eval- uation of the possibility of monitoring and controlling the dynamic behavior of a rotating machine with a cracked shaft by using an Electro-Magnetic Actuator (EMA). The EMA is located at the mid-span of the rotor to provide active control. The opening and closure (breathing) of the crack is deter- mined by the stress field over its cross section resulting from the dynamic bending moment. The system is nonlinear due to the fact that the crack parameters must be determined for each time step and the EMA introduces forces that are inversely proportional to the square of the gap value be- tween the stator and the rotor. The model developed takes into account the behavior of the crack and the in uence of the EMA. Simulations were carried out to access the pos- sibility of controlling the breathing mechanism. The results obtained demonstrate the possibility of using the EMA in or- der to keep the crack closed along the rotation of the rotor, thus forming a self-healing scheme for the cracked rotor.

Pedrosa G.V.,Federal University of Uberlndia | Zorzo Barcelos C.A.,Federal University of Uberlndia | Aurelio Batista M.,Federal University of Santa Catarina
Proceedings - IEEE International Symposium on Circuits and Systems | Year: 2011

Content-Based Image Retrieval (CBIR) systems have been developed to support the image retrieval based on image properties, such as color, shape and texture. In this paper, we are concerned with shape-based image retrieval. In this context, we propose a method to describe shapes based on salience points. The proposed descriptor utilizes a salience detector which is robust to noise, and an elastic matching algorithm to measure the similarity between two shapes represented by their salience points. The proposed approach is robust to noise and gives good results in recognizing shapes of the same class, even if they are represented by a different number of salience points. © 2011 IEEE.

Gonalves A.L.R.,Federal University of Uberlndia | Rocha C.A.,Federal University of Uberlndia | Gonzaga H.T.,Federal University of Uberlndia | Gonalves-Pires M.D.R.D.F.,Federal University of Uberlndia | And 2 more authors.
Diagnostic Microbiology and Infectious Disease | Year: 2012

The aim of this study was to detect levels of IgG and IgA by enzyme-linked immunosorbent assay (ELISA) using alkaline extracts of larvae, adult female worms, and eggs of Strongyloides venezuelensis as antigen. One hundred twenty serum samples divided into 3 groups were analysed: group I (40 strongyloidiasis patients), group II (40 patients with other parasitic infections), and group III (40 healthy subjects). Statistical variations were analyzed using analysis of variance. There was a significant statistical difference (P < 0.001) in the detection of antibodies in group I between larvae and female antigens and between larvae and egg antigens, with higher positivity using larvae antigen. The larvae antigen showed the highest values for sensitivity, specificity, and diagnostic efficiency in ELISA. This study is the first that examines the use of adult female worm and egg antigens to detect antibodies for human strongyloidiasis diagnosis compared with the larval extract. By comparing all 3 extracts, larval antigens demonstrated better diagnostic parameters. © 2012 Elsevier Inc.

Motta Jafelice R.,Federal University of Uberlndia | Almeida C.,Federal University of Uberlndia | Meyer J.F.C.A.,University of Campinas | Vasconcelos H.L.,Federal University of Uberlndia
Nonlinear Analysis: Real World Applications | Year: 2011

This paper proposes a model for the reoccupation of ants in a region of attraction, using evolutive partial differential diffusionadvection equations, in which the population dispersion and velocity in directions x and y are fuzzy parameters. The domain under study contains an attractive region, representing areas with high concentrations of palatable host plants with better nutritious qualities. The algorithm developed here uses information about the foraging behavior of a leaf-cutting ant colony of the Amazon region in northern Brazil. In the first model, we determined the numerical solution of the partial differential deterministic equation with constant dispersion and velocity, without incorporating uncertainties that may occur in this type of biological phenomenon. In the second model, we calculated the numerical solution of the partial differential equation, determining the dispersion at each iteration and for each triangular finite element. The dispersion was determined from a fuzzy rule-based system that depends on the number of individuals of the population and on the characteristics of the terrain. In this model, we also considered the velocity along the x and y directions as a fuzzy parameter that depends on the ant movement characteristics on the terrain in the y and x directions, respectively. The two models produced solutions consistent with ant behavior in response to the proximity of an attractive region, as stated in the papers by Shepherd (1982) [2] and Vasconcelos (1999) [3], but the fuzzy model incorporates uncertainties that do occur in the biological phenomenon under study. © 2011 Elsevier Ltd. All rights reserved.

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