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Pirassununga, Brazil

Nascimento J.,Brazilian Technological Institute of Aeronautics | Pelegrini M.,Academia da Forca Aerea | Ferrao L.F.A.,Brazilian Technological Institute of Aeronautics | Roberto-Neto O.,Institute Estudos Avancados | MacHado F.B.C.,Brazilian Technological Institute of Aeronautics
Journal of the Brazilian Chemical Society | Year: 2011

Barrier heights of the internal rotation and inversion motions of methylamine, dimethylamine and trimethylamine molecules were calculated with the CCSD(T)//B3LYP methodology in combination with the cc-pVTZ, cc-pVQZ, and cc-pCVTZ basis sets of Dunning. The complete basis set (CBS) extrapolation procedure and core-valence (CV) correlation effects are also examined to the barrier heights. Our best estimate results (CCSD(T)/CBS+CV//B3LYP/cc-pVQZ) are in very good agreement with the experimental data, indicating the use of this methodology to provide accurate predictions of structures and barrier heights for other systems. © 2011 Sociedade Brasileira de Química. Source

Mendonca P.E.M.F.,Academia da Forca Aerea | Marchiolli M.A.,Avenida General Osorio 414 | Milburn G.J.,University of Queensland
International Journal of Quantum Information | Year: 2015

For every N-qubit density matrix written in the computational basis, an associated "X-density matrix" can be obtained by vanishing all entries out of the main-and anti-diagonals. It is very simple to compute the genuine multipartite (GM) concurrence of this associated N-qubit X-state, which, moreover, lower bounds the GM-concurrence of the original (non-X) state. In this paper, we rely on these facts to introduce and benchmark a heuristic for estimating the GM-concurrence of an arbitrary multiqubit mixed state. By explicitly considering two classes of mixed states, we illustrate that our estimates are usually very close to the standard lower bound on the GM-concurrence, being significantly easier to compute. In addition, while evaluating the performance of our proposed heuristic, we provide the first characterization of GM-entanglement in the steady states of the driven Dicke model at zero temperature. © 2015 World Scientific Publishing Company. Source

Zheng J.,University of Minnesota | Rocha R.J.,Brazilian Technological Institute of Aeronautics | Pelegrini M.,Academia da Forca Aerea | Ferrao L.F.A.,Brazilian Technological Institute of Aeronautics | And 4 more authors.
Journal of Chemical Physics | Year: 2012

The abstraction and addition reactions of H with trans-N 2H 2 are studied by high-level ab initio methods and density functional theory. Rate constants were calculated for these two reactions by multistructural variational transition state theory with multidimensional tunneling and including torsional anharmonicity by the multistructural torsion method. Rate constants of the abstraction reaction show large variational effects, that is, the variational transition state yields a smaller rate constant than the conventional transition state; this results from the fact that the variational transition state has a higher zero-point vibrational energy than the conventional transition state. The addition reaction has a classical barrier height that is about 1 kcalmol lower than that of the abstraction reaction, but the addition rates are lower than the abstraction rates due to vibrational adiabaticity. The calculated branching ratio of abstraction to addition is 3.5 at 200 K and decreases to 1.2 at 1000 K and 1.06 at 1500 K. © 2012 American Institute of Physics. Source

Fanchini F.F.,Federal University of Ouro Preto | de Mendonca P.E.M.F.,Academia da Forca Aerea | Napolitano R.J.,University of Sao Paulo
Quantum Information and Computation | Year: 2011

We present a constructive argument to demonstrate the universality of the sudden death of entanglement in the case of two non-interacting qubits, each of which generically coupled to independent Markovian environments at zero temperature. Conditions for the occurrence of the abrupt disappearance of entanglement are determined and, most importantly, rigourously shown to be almost always satisfied: Dynamical models for which the sudden death of entanglement does not occur are seen to form a highly idealized zero-measure subset within the set of all possible quantum dynamics. © Rinton Press. Source

Silva C.,Academia da Forca Aerea | Rocha B.,University of Victoria | Suleman A.,University of Victoria
Journal of Physics: Conference Series | Year: 2011

With the application of newer materials, such as composite materials, and growing complexity and capacity of current aircraft structures, reliably and completely assess the condition of the total structures in real time is then of growing and utmost importance. PZT Network and Phased Array, Lamb wave based Structural Health Monitoring (SHM) systems were developed to be applied to thin panels. The selection of transducers, their size and selected locations for their installation are described. The development and selection of the signal generation and data acquisition systems is also presented in detail. The requirements conducing to the development and selection of these systems are laid and particularly the selection of the actuation signal applied is justified. The development of a damage detection algorithm based in the comparison of the current structural state to a reference state is described, to detect damage reflected Lamb waves. Such method was implemented in software and integrated in the SHM system developed. Subsequently the detection algorithm, based in discrete signals correlation, was further improved by incorporating statistical methods. For phased arrays, a novel damage location algorithm is presented based on the individual sensors response. A visualization method based concurrently in the statistical methods developed and superposition of the different results obtained from a test set was implemented. These tests conducted to the successful and repeatable detection of 1mm damages in a multiple damaged plate with great confidence. Finally, a brief comparison and a hybrid system implementation is presented. © 2011 Published under licence by IOP Publishing Ltd. Source

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