Estudo das limitações impostas ao amortecimento de oscilações eletromecânicas pelos zeros da FTMA de controladores suplementares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Pole placement by coordinated tuning of Power System Stabilizers and FACTS-POD stabilizers

This work presents the application of the Decentralized Modal Control method for pole placement in multimachine power systems utilizing FACTS (Flexible AC Transmission Systems), STATCOM (Static Synchronous Compensator) and UPFC (Unified Power Flow Controller) devices. For this, these devices are equipped with supplementary damping controllers, denominated POD ( Power Oscillation Damping), achieving a coordinated project with local controllers (Power System Stabilizers - PSS). Comparative analysis on the function of damping of the FACTS, STATCOM and UPFC is performed using the New England System that has 10 generators, 39 buses and 46 transmission lines. (c) 2011 Elsevier Ltd. All rights reserved.

Cost assessment of efficiency losses in hydroelectric plants

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Stability analysis of power systems described with detailed models by automatic method

The power system stability analysis is approached taking into explicit account the dynamic performance of generators internal voltages and control devices. The proposed method is not a direct method in the usual sense since conclusion for stability or instability is not exclusively based on energy function considerations but it is automatic since the conclusion is achieved without an analyst intervention. The stability test accounts for the nonconservative nature of the system with control devices such as the automatic voltage regulator (AVR) and automatic generation control (AGC) in contrast with the well-known direct methods. An energy function is derived for the system with machines forth-order model, AVR and AGC and it is used to start the analysis procedure and to point out criticalities. The conclusive analysis itself is made by means of a method based on the definition of a region surrounding the equilibrium point where the system net torque is equilibrium restorative. This region is named positive synchronization region (PSR). Since the definition of the PSR boundaries have no dependence on modelling approximation, the PSR test conduces to reliable results. (C) 2008 Elsevier Ltd. All rights reserved.

Estudo das percepções ambientais e de ações educativas promotoras da biodiversidade em unidade de conservação no Rio Grande do Norte

Important issues involving the awakening to the need for conservation of biodiversity and the importance of establishing protected areas as a strategy in pursuit of environmental protection, are increasingly being developed in biological and social investigative fields. In this sense, this research aimed to emphasize the use of environmental perception of social agents are significant elements for the understanding of the man / nature, and develop educational activities aimed at raising awareness and changing attitudes towards environmental issues thus promoting reflections on Environmental Education (EE) as a critical and transformative tool for conservation of rich biological diversity. This research covers as a place of study, schools located in the Environmental Protection Area Jenipabu (APAJ), Rio Grande do Norte. Methodology in general, we highlight the use of questionnaires and mind maps as generators of the contents of empirical research, and execution of content analysis for the treatment of data collected. This dissertation has two chapters in the form of scientific articles, where the first is entitled: "Study of the perceptions and evaluation of interactions concerning environmental education in schools in a conservation area of Rio Grande do Norte - Brazil", obtaining thus a primary diagnosis for analysis about the visions that students and teachers from two schools located in APAJ have on the environment. The second article, entitled: "Effective and analysis of educational activities that promote biodiversity in a coastal area of Environmental Protection Northeast - Brazil" provides an analysis of the educational use of biodiversity as a way to raise awareness of the need for environmental conservation. It appears from research that there is a lack of training in EA by teachers, but there is a need for greater involvement of students in conservation areas, however, from the analysis of educational activities, we observed that the effectiveness of such actions acts to promote awareness and change in actors involved. Thus, environmental education needs to take into account the different perceptions found in each individual, and it can not be based solely on transmission of knowledge, so that we reach a model of conservation.

Control of respiration in fish, amphibians and reptiles

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

Classification of states in S0(8) proton-neutron pairing model

lsoscalar (T = 0) plus isovector (T = 1) pairing Hamiltonian in LS-coupling. which is important for heavy N = Z nuclei, is solvable in terms of a SO(8) Lie algebra for three special values of the mixing parameter that measures the competition between the T = 0 aid T = 1 pairing. The SO(8) algebra is generated, amongst others, by the S = 1, T = 0 and S = 0, T = 1 pair creation and annihilation operators and corresponding to the three values of the mixing parameter, there are three chains of subalgebras: SO(8) superset of SOST (6) superset of SOS(3) circle times SOT(3), SO(8) superset of [SOS(5) superset of SOS(3)] circle times SOT(3) and SO(8) superset of [SOT(5) superset of SOT(3)] circle times SOS(3). Shell model Lie algebras, with only particle number conserving generators, that are complementary to these three chains of subalgebras are identified and they are used in the classification of states for a given number of nucleons. The classification problem is solved explicitly tor states with SO(8) seniority nu = 0, 1, 2, 3 and 4. Using them, hand structures in isospin space are identified for states with nu = 0, 1, 2 and 3. (c) 2005 Elsevier B.V. All rights reserved.

Bosonic Dp-branes at finite temperature in TFD approach

A general formulation of Thermo Field Dynamics using transformation generators that form the SU(1, 1) group, is presented and applied to the closed bosonic string and for bosonic D-p-brane with an external field.

Lorentz invariance of the pure spinor BRST cohomology for the superstring

In a previous Letter. The BRST cohomology in the pure spinor formalism of the superstring was shown to coincide with the light-cone Green-Schwarz spectrum by using an SO(8) parameterization of the pure spinor. In this Letter, the SO(9, 1) Lorentz generators are explicitly constructed using this SO(8) parameterization, proving the Lorentz invariance of the pure spinor BRST cohomology. (C) 2001 Published by Elsevier B.V. B.V.

Pure spinor formalism as an N=2 topological string

Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are added to the pure spinor formalism for the superstring. Twisted (c) over cap = 3 N = 2 generators are then constructed where the pure spinor BRST operator is the fermionic spin-one generator, and the formalism is interpreted as a critical topological string. Three applications of this topological string theory include the super-Poincare covariant computation of multiloop superstring amplitudes without picture-changing operators, the construction of a cubic open superstring field theory without contact-term problems, and a new four-dimensional version of the pure spinor formalism which computes F-terms in the spacetime action.

Primeval symmetries

A detailed examination of the Killing equations in Robertson-Walker coordinates shows how the addition of matter and/or radiation to a de Sitter Universe breaks the symmetry generated by four of its Killing fields. The product U = a(2) H of the squared scale parameter by the time-derivative of the Hubble function encapsulates the relationship between the two cases: the symmetry is maximal when U is a constant, and reduces to the six-parameter symmetry of a generic Friedmann-Robertson-Walker model when it is not. As the fields physical interpretation is not clear in these coordinates, comparison is made with the Killing fields in static coordinates, whose interpretation is made clearer by their direct relationship to the Poincare group generators via Wigner-Inonu contractions.

gamma p and gamma gamma scattering from (p)over-bar-p, pp forward amplitudes in a QCD eikonal model with a dynamical gluon mass

We examine the gamma p photoproduction and the hadronic gamma gamma total cross sections by means of a QCD eikonal model with a dynamical infrared mass scale. In this model, where the dynamical gluon mass is the natural regulator for the tree level gluon-gluon scattering, the gamma p and gamma gamma total cross sections are derived from the pp and (p) over barp forward scattering amplitudes assuming vector meson dominance and the additive quark model. We show that the validity of the cross section factorization relation sigma(pp)/sigma(gamma p)=sigma(gamma p)/sigma(gamma gamma) is fulfilled depending on the Monte Carlo model used to unfold the hadronic gamma gamma cross section data, and we discuss in detail the case of sigma(gamma gamma -> hadrons) data with W-gamma gamma> 10 GeV unfolded by the Monte Carlo generators PYTHIA and PHOJET. The data seems to favor a mild dependence with the energy of the probability (P-had) that the photon interacts as a hadron.

Measurement of Z/gamma* plus jet plus X angular distributions in p(p)over-bar collisions at root s=1.96 TeV

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

Measurement of direct photon pair production cross sections in p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the normalized Z/gamma* -> mu(+)mu(-) transverse momentum distribution in p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)