NUMERICAL SIMULATION OF AIRFOILS APPLIED TO UAVs

This essay aims the process optimization when referred to aeronautical projects. By using mesh generators softwares and simulations made in CFD, the article employs numerical techniques to simulate airfoils and shows that is possible to extract accurated and conservative outcomes when compared to wind tunnel results. The test cases studied were based on the Selig 1223 type of airfoil and developed into the ANSYS platform, whereas by using the ICEM mesh tool, structured meshs were generated and imported to the CFX enviroment, where they could be simulated and analyzed

A model for time-dependent cosmological constant and its consistency with the present Friedmann universe

We use a model where the cosmological term can be related to the chiral gauge anomaly of a possible quantum scenario of the initial evolution of the universe. We show that this term is compatible with the Friedmann behavior of the present universe.Comment: 5 pages, Revtex 4, twocolumn (minor corrections and improved reference list. To appear in Classical and Quantum Gravity

Symmetry transform in the Faddeev-Jackiw quantization of dual models

We study the presence of symmetry transformations in the Faddeev-Jackiw approach for constrained systems. Our analysis is based in the case of a particle submitted to a particular potential which depends on an arbitrary function. The method is implemented in a natural way and symmetry generators are identified. These symmetries permit us to obtain the absent elements of the sympletic matrix which complement the set of Dirac brackets of such a theory. The study developed here is applied in two different dual models. First, we discuss the case of a two-dimensional oscillator interacting with an electromagnetic potential described by a Chern-Simons term and second the Schwarz-Sen gauge theory, in order to obtain the complete set of non-null Dirac brackets and the correspondent Maxwell electromagnetic theory limit.Comment: 22 pages, RevTex file, no figur

Gauging the SU(2) Skyrme model

In this paper the SU(2) Skyrme model will be reformulated as a gauge theory and the hidden symmetry will be investigated and explored in the energy spectrum computation. To this end we purpose a new constraint conversion scheme, based on the symplectic framework with the introduction of Wess-Zumino (WZ) terms in an unambiguous way. It is a positive feature not present on the BFFT constraint conversion. The Dirac's procedure for the first-class constraints is employed to quantize this gauge invariant nonlinear system and the energy spectrum is computed. The finding out shows the power of the symplectic gauge-invariant formalism when compared with another constraint conversion procedures present on the literature.Comment: revised version, to appear in Phys.Rev.

Hamiltonian symplectic embedding of the massive noncommutative U(1) Theory

We show that the massive noncommutative U(1) theory is embedded in a gauge theory using an alternative systematic way, which is based on the symplectic framework. The embedded Hamiltonian density is obtained after a finite number of steps in the iterative symplectic process, oppositely to the result proposed using the BFFT formalism. This alternative formalism of embedding shows how to get a set of dynamically equivalent embedded Hamiltonian densities.Comment: 16 pages, no figures, revtex4, corrected version, references additione

Parity Violating Gravitational Coupling Of Electromagnetic Fields

A manifestly gauge invariant formulation of the coupling of the Maxwell theory with an Einstein Cartan geometry is given, where the space time torsion originates from a massless Kalb-Ramond field augmented by suitable U(1) Chern Simons terms.We focus on the situation where the torsion violates parity, and relate it to earlier proposals for gravitational parity violation.Comment: 7 Pages, Latex . no figures, Replaced with Revtex version, many references added and typos correcte

Renormalizability of the Dynamical Two-Form

A proof of renormalizability of the theory of the dynamical non-Abelian two-form is given using the Zinn-Justin equation. Two previously unknown symmetries of the quantum action, different from the BRST symmetry, are needed for the proof. One of these is a gauge fermion dependent nilpotent symmetry, while the other mixes different fields with the same transformation properties. The BRST symmetry itself is extended to include a shift transformation by use of an anticommuting constant. These three symmetries restrict the form of the quantum action up to arbitrary order in perturbation theory. The results show that it is possible to have a renormalizable theory of massive vector bosons in four dimensions without a residual Higgs boson.Comment: revtex, 35p. additional discussion about the auxiliary vector field and possible gauge choices, relevant to the question of validity of perturbative expansion, version to be published in Phys.Rev.

On singular Lagrangians affine in velocities

The properties of Lagrangians affine in velocities are analyzed in a geometric way. These systems are necessarily singular and exhibit, in general, gauge invariance. The analysis of constraint functions and gauge symmetry leads us to a complete classification of such Lagrangians.Comment: AMSTeX, 22 page

Dendê uma opção de cultivo para áreas degradadas na Amazônia.

O cultivo de dende surge como opcao para exploracao na Amazonia, tendo em vista sua adaptacao as condicoes edafoclimaticas da regiao. Esta cultura, com vida util de 25 anos, inicia sua producao aos quatro anos, tem produtividade media de 4t/oleo/ha/ano - 6t/oleo/ha/ano, colheita durante o ano todo, ausencia de entressafra, demanda expressivo contigente de mao-de-obra, fixando, dessa maneira, o homem na zona rural. Buscando apoiar e incentivar a expansao da cultura, a EMBRAPA-CPAA e o IRHO implantaram, no Amazonas, varios ensaios, objetivando desenvolver um programa de melhoramento, para a obtencao de material mais produtivo e melhor adaptado as condicoes da regiao. A producao media experimental de cachos aos quatro anos de idade variou de 12t/ha. Atualmente, EMBRAPA/CIRAD produzem sementes comerciais para atender os dendeicultores da regiao