A new spin-2 self-dual model in D=2+1

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nonuniqueness of the Fierz-Pauli mass term for a nonsymmetic tensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of the fretting fatigue behaviour of commercially pure titanium

Fretting fatigue occurs when the contact surfaces of two components undergo small oscillatory movement while they are subjected to a clamping force. A cyclic external load gives rise to the early initiation of fatigue cracks, thus reducing their service life. In this paper, the fretting fatigue behaviour of commercially pure titanium flat samples (1.5 mm thick) is evaluated. A fretting device composed of a frame, load cell, and two screw-mounted cylindrical fretting pads with convex extremities was built and set to a servo-hydraulic testing machine. The fatigue tests were conducted under load control at a frequency of 10 Hz and stress ratio R = 0.1, with various contact load values applied to the fretting pads. Additional tests under inert environment allowed assessing the role of oxidation on the wear debris formation. The fracture surfaces and fretting scars were analysed via scanning electron microscopy in order to evaluate the surface damage evolution and its effect on the fatigue crack features. The effect of the fretting condition on the S-N curve of the material in the range of 10(4)-10(6) cycles is described. Fatigue crack growth calculations allowed estimating the crack initiation and propagation lives under fretting conditions. The effect of the fretting condition in fatigue life is stronger for the lower values of cyclic stress and does not seem to depend on the contact loading value.

Analog neural nonderivative optimizers

Continuous-time neural networks for solving convex nonlinear unconstrained;programming problems without using gradient information of the objective function are proposed and analyzed. Thus, the proposed networks are nonderivative optimizers. First, networks for optimizing objective functions of one variable are discussed. Then, an existing one-dimensional optimizer is analyzed, and a new line search optimizer is proposed. It is shown that the proposed optimizer network is robust in the sense that it has disturbance rejection property. The network can be implemented easily in hardware using standard circuit elements. The one-dimensional net is used as a building block in multidimensional networks for optimizing objective functions of several variables. The multidimensional nets implement a continuous version of the coordinate descent method.

Hardware implementation of an analog neural nonderivative optimizer

Analog neural systems that can automatically find the minimum value of the outputs of unknown analog systems, described by convex functions, are studied. When information about derivative or gradient are not used, these systems are called analog nonderivative optimizers. An electronic circuit for the analog neural nonderivative optimizer proposed by Teixeira and Zak, and its simulation with software PSPICE, is presented. With the simulation results and hardware implementation of the system, the validity of the proposed optimizer can be verified. These results are original, from the best of the authors knowledge.

On relaxed LMI-based design for fuzzy controllers

Relaxed conditions for stability of nonlinear continuous-time systems given by fuzzy models axe presented. A theoretical analysis shows that the proposed method provides better or at least the same results of the methods presented in the literature. Digital simulations exemplify this fact. This result is also used for fuzzy regulators design. The nonlinear systems are represented by fuzzy models proposed by Takagi and Sugeno. The stability analysis and the design of controllers axe described by LMIs (Linear Matrix Inequalities), that can be solved efficiently using convex programming techniques.

On relaxed LMI-based designs for fuzzy regulators and fuzzy observers

Relaxed conditions for stability of nonlinear, continuous and discrete-time systems given by fuzzy models are presented. A theoretical analysis shows that the proposed methods provide better or at least the same results of the methods presented in the literature. Numerical results exemplify this fact. These results are also used for fuzzy regulators and observers designs. The nonlinear systems are represented by fuzzy models proposed by Takagi and Sugeno. The stability analysis and the design of controllers are described by linear matrix inequalities, that can be solved efficiently using convex programming techniques. The specification of the decay rate, constrains on control input and output are also discussed.

A Bilevel Approach to Transmission Expansion Planning Within a Market Environment

We present a bilevel model for transmission expansion planning within a market environment, where producers and consumers trade freely electric energy through a pool. The target of the transmission planner, modeled through the upper-level problem, is to minimize network investment cost while facilitating energy trading. This upper-level problem is constrained by a collection of lower-level market clearing problems representing pool trading, and whose individual objective functions correspond to social welfare. Using the duality theory the proposed bilevel model is recast as a mixed-integer linear programming problem, which is solvable using branch-and-cut solvers. Detailed results from an illustrative example and a case study are presented and discussed. Finally, some relevant conclusions are drawn.

Robust State-Derivative Feedback LMI-Based Designs for Linear Descriptor Systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Multi Objective Evolutionary Algorithm Applied to the Optimal Power Flow Problem

This work presents the application of a multiobjective evolutionary algorithm (MOEA) for optimal power flow (OPF) solution. The OPF is modeled as a constrained nonlinear optimization problem, non-convex of large-scale, with continuous and discrete variables. The violated inequality constraints are treated as objective function of the problem. This strategy allows attending the physical and operational restrictions without compromise the quality of the found solutions. The developed MOEA is based on the theory of Pareto and employs a diversity-preserving mechanism to overcome the premature convergence of algorithm and local optimal solutions. Fuzzy set theory is employed to extract the best compromises of the Pareto set. Results for the IEEE-30, RTS-96 and IEEE-354 test systems are presents to validate the efficiency of proposed model and solution technique.

The use of scaled semivariograms to plan soil sampling in sugarcane fields

Spatial sampling designs used to characterize the spatial variability of soil attributes are crucial for science studies. Sample planning for the interpolation of a regionalized variable may use several criteria, which could be best selected from an estimated semivariogram from a previously established grid. The objective of this study was to optimize the procedure for scaled semivariogram use to plan soil sampling in sugarcane fields in the Alfisol and Oxisol regions of Jaboticabal Town in So Paulo State, Brazil. A scaled semivariogram for several soil chemical attributes was estimated from the data obtained from two grids positioned on a sugarcane field area, sampled at a depth of 0.0-0.5 m. The research showed that regular grids with uniform intervals did not express the real spatial variability of the soil attributes of Oxisols and Alfisols in the study area. The calculated final sampling density based on the scaled parameters of the semivariogram was one sample for each 2 ha in Area 1 (convex landscape) and one sample for each 1 ha in Area 2 (linear landscape), as indicated by SANOS 0.1 software. The combined use of the simulation programs and scaled semivariograms can be used to define sampling points. These results may help in soil fertility mapping and thereby improve nutrient management in sugarcane crops.

Avaliações radiográfica e ultra-sonográfica do joelho de ovinos

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

Características de carcaça e qualidade de carne de novilhos superprecoces de três grupos genéticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação das queixas estético-funcionais em pacientes portadores de deformidades dentofaciais

OBJETIVO: avaliar as queixas relatadas por pacientes portadores de deformidades dentofaciais como fatores motivadores na procura do tratamento ortodôntico-cirúrgico. METODOLOGIA: foram verificados 130 prontuários de pacientes em tratamento no CEDEFACE - Araraquara, apresentando um período pós-operatório mínimo de 6 meses e idade média de 30,9 anos. A classificação dos tipos de deformidades foi realizada por meio de análise das telerradiografias e das fotografias, sendo subdivididas em três grupos, de acordo com suas características de perfil facial. As informações referentes às queixas foram colhidas por meio de questionários e divididas em duas categorias: queixa principal e queixas secundárias. em relação à análise estatística, utilizaram-se medidas de tendência central (média e mediana) e de variabilidade (variação e desvio-padrão) para descrever as variáveis numéricas de idade. As variáveis categóricas de gênero, deformidades dentofaciais e queixas foram descritas através da distribuição de freqüências, com nível de significância de 5%. RESULTADOS: observou-se predominância do gênero feminino, na razão de 2:1. Na maioria das vezes, a deformidade requeria tratamento somente na maxila ou somente na mandíbula. No gênero feminino predominaram as deformidades de perfil convexo (46%); no gênero masculino houve predominância de deformidades de perfil côncavo (48,8%). As queixas principais evidenciaram que o anseio estético é predominante, tanto no gênero feminino quanto no masculino. CONCLUSÃO: os anseios de melhora estética foram predominantes em ambos os gêneros. A maioria dos pacientes também apresentou anseio por melhora funcional. Queixas de dor orofacial foram observadas em metade da casuística, sendo a segunda queixa mais relatada.

Cytotoxic effects and pulpal response caused by a mineral trioxide aggregate formulation and calcium hydroxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)