De Biasi R.S.,Military Institute of Engineering of Rio de Janeiro |
Grillo M.L.N.,State University of Rio de Janeiro
Ceramics International | Year: 2013
Electron magnetic resonance (EMR) line widths of Mn2+ in CdO were measured in samples doped with small concentrations (up to 1.0 mol%) of Mn. The line width of one of the lines, which corresponds to the1/2 1/2>↔|-1/2 1/2> transition, was found to change in a predictable way with Mn concentration, according to the theoretical equation ΔH pp=2.05+370f(1-f)42, where ΔHpp is the line width in mT and f is the Mn concentration in mol%. The experimental results show that the technique can be used to measure, rapidly and nondestructively, small concentrations of Mn in commercial CdO. © 2012 Elsevier Ltd and Techna Group S.r.l.
Ellmauthaler A.,Federal University of Rio de Janeiro |
Pagliari C.L.,Military Institute of Engineering of Rio de Janeiro |
Da Silva E.A.B.,Federal University of Rio de Janeiro
IEEE Transactions on Image Processing | Year: 2013
Multiscale transforms are among the most popular techniques in the field of pixel-level image fusion. However, the fusion performance of these methods often deteriorates for images derived from different sensor modalities. In this paper, we demonstrate that for such images, results can be improved using a novel undecimated wavelet transform (UWT)-based fusion scheme, which splits the image decomposition process into two successive filtering operations using spectral factorization of the analysis filters. The actual fusion takes place after convolution with the first filter pair. Its significantly smaller support size leads to the minimization of the unwanted spreading of coefficient values around overlapping image singularities. This usually complicates the feature selection process and may lead to the introduction of reconstruction errors in the fused image. Moreover, we will show that the nonsubsampled nature of the UWT allows the design of nonorthogonal filter banks, which are more robust to artifacts introduced during fusion, additionally improving the obtained results. The combination of these techniques leads to a fusion framework, which provides clear advantages over traditional multiscale fusion approaches, independent of the underlying fusion rule, and reduces unwanted side effects such as ringing artifacts in the fused reconstruction. © 1992-2012 IEEE.
Silva W.B.,Military Institute of Engineering of Rio de Janeiro |
Freitas C.C.,National Institute for Space Research |
Sant'Anna S.J.S.,National Institute for Space Research |
Frery A.C.,Federal University of Alagoas
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2013
A new classifier for Polarimetric SAR (PolSAR) images is proposed and assessed in this paper. Its input consists of segments, and each one is assigned the class which minimizes a stochastic distance. Assuming the complex Wishart model, several stochastic distances are obtained from the h-φ family of divergences, and they are employed to derive hypothesis test statistics that are also used in the classification process. This article also presents, as a novelty, analytic expressions for the test statistics based on the following stochastic distances between complex Wishart models: Kullback-Leibler, Bhattacharyya, Hellinger, Rényi, and Chi-Square; also, the test statistic based on the Bhattacharyya distance between multivariate Gaussian distributions is presented. The classifier performance is evaluated using simulated and real PolSAR data. The simulated data are based on the complex Wishart model, aiming at the analysis of the proposal with controlled data. The real data refer to a complex L-band image, acquired during the 1994 SIR-C mission. The results of the proposed classifier are compared with those obtained by a Wishart per-pixel/contextual classifier, and we show the better performance of the region-based classification. The influence of the statistical modeling is assessed by comparing the results using the Bhattacharyya distance between multivariate Gaussian distributions for amplitude data. The results with simulated data indicate that the proposed classification method has very good performance when the data follow the Wishart model. The proposed classifier also performs better than the per-pixel/contextual classifier and the Bhattacharyya Gaussian distance using SIR-C PolSAR data. © 2013 IEEE.
Borges Jr. I.,Military Institute of Engineering of Rio de Janeiro
Journal of Molecular Modeling | Year: 2014
Singlet, triplet and ionized states of the energetic molecule 1,1-diamino-2,2-dinitroethylene, known as FOX-7 or DADNE, were investigated using the symmetry-adapted-cluster configuration interaction (SAC-CI) ab initio wave function. The 20 computed singlet transitions, with 2 exceptions, were bright. The most intense singlet transitions were of the nO→π type-typical of molecules having nitro groups. Fast intersystem crossing (ISC) from the 11A, 21A and 81A bright singlet transitions is possible. Other feasible ISC processes are discussed. The computed singlet and ionization spectra have similar features when compared to nitramide and N,N-dimethylnitramine molecules, which have only a nitro group. The ionization energies of the first 20 states have differences in comparison with Koopmans' energy values that can reach 3 eV. Moreover, the character of the first ionized states, dominated by single ionizations, is not the same when compared with the character resulting from application of Koopmans' theorem. © 2014 Springer-Verlag.
Dias M.H.C.,Military Institute of Engineering of Rio de Janeiro |
De Assis M.S.,Federal University of Fluminense
IEEE Transactions on Antennas and Propagation | Year: 2011
A vegetation path loss model was derived from measurements performed in a downtown park in Rio de Janeiro city, from 0.9 to 1.8 GHz. The resulting equation followed the general formulation in ITU-R Recommendation P.833. A comparative analysis was carried out with other empirical models, assessing statistical adherence to the available data. Coherent results were observed. © 2006 IEEE.
Caldeira A.B.,Military Institute of Engineering of Rio de Janeiro
Numerical Heat Transfer; Part A: Applications | Year: 2016
Ignition and combustion of an infinite linear array of gaseous fuel pockets in a stagnant oxidizing environment under the microgravity condition is studied by a numerical approach. The combustion process is considered isobaric and the fluid motion is induced by density gradients due to the heat and mass transfer processes. A simple finite chemical reaction mechanism and the ideal gas equation of state are considered. The thermophysical properties, except density, are assumed constant. The Finite Volume Method is used with a hybrid non-staggered grid in a generalized system of coordinates. The SIMPLEC algorithm solves the modified pressure–velocity coupling. The Damköhler number effects on flame dynamics and on the fuel consumption are analyzed. Three stages in the burning processes: the induction time, the flame propagation and the diffusive burning are identified. The merging processes of the fuel pockets and of the flames are depicted. 2016 Copyright © Taylor & Francis Group, LLC
Guimaraes A.,Military Institute of Engineering of Rio de Janeiro |
Ait-El-Fquih B.,Orange S.A. |
Desbouvries F.,Orange S.A.
IEEE Transactions on Wireless Communications | Year: 2010
We introduce a new sequential importance sampling (SIS) algorithm which propagates in time a Monte Carlo approximation of the posterior fixed-lag smoothing distribution of the symbols under doubly-selective channels. We perform an exact evaluation of the optimal importance distribution, at a reduced computational cost when compared to other optimal solutions proposed for the same state-space model. The method is applied as a soft input-soft output (SISO) blind equalizer in a turbo receiver framework and simulation results are obtained to show its outstanding BER performance. © 2010 IEEE.
Elias C.N.,Military Institute of Engineering of Rio de Janeiro |
Meirelles L.,Gothenburg University
Expert Review of Medical Devices | Year: 2010
In the beginning of implantology, the procedures adopted for treating patients were performed in two surgical phases with an interval of 3-6 months. Nowadays, it is possible to insert and load a dental implant in the same surgical procedure. This change is due to several factors, such as improvement of surgical technique, modifications of the implant design, increased quality of implant manufacturing, development of the surgical instruments quality, careful patient screening and adequate treatment of the implant surface. The clinical results show that adequate treatment of surfaces is crucial for reducing healing time and treating at-risk patients. The surface properties of dental implants can be significantly improved at the manufacturing stage, affecting cells activity during the healing phase that will ultimately determine the host tissue response, a fundamental requirement for clinical success. This review focuses on different types of dental implant surfaces and the influence of surface characteristics on osseointegration. © 2010 Expert Reviews Ltd.
Chamorro Enriquez D.A.,Military Institute of Engineering of Rio de Janeiro |
Da Cruz A.R.,Military Institute of Engineering of Rio de Janeiro |
Rocco Giraldi M.T.M.,Military Institute of Engineering of Rio de Janeiro
Optics and Laser Technology | Year: 2012
In this work, we propose a configuration of a hybrid fiber Bragg grating together with a long period grating sensor used for simultaneously detect surrounding refractive index and temperature to be applied in aqueous environment and to reveal pollution. We present the simulation of such sensor and analyze the reflected wavelength and amplitude variations of the fiber Bragg grating spectrum to obtain the temperature and the external refractive index variations, respectively. The results show that the fiber Bragg grating reflected amplitude change depends on the variation of the long period grating transmission spectrum with the surrounding refractive index modification and the reflected wavelength shift depends on the temperature of the aqueous solution. © 2011 Elsevier Ltd. All rights reserved.
Vaiss V.S.,Federal University of Juiz de fora |
Borges Jr. I.,Military Institute of Engineering of Rio de Janeiro |
Leitao A.A.,Federal University of Juiz de fora
Journal of Physical Chemistry C | Year: 2011
Density Functional Theory (DFT) calculations with periodic boundary conditions were used to investigate a degradation reaction mechanism of the Sarin molecule (isopropyl methylphosphonofluoridate, C 4H 10FO 2P) using the layered hydroxide brucite (Mg(OH) 2). We computed the adsorption of Sarin on brucite including the infrared vibrational spectrum of gas and adsorbed Sarin, reaction paths, activation energies, and the Gibbs free energy differences (ΔG). The isopropyl methylphos- phonate molecule and the Mg(OH) 2-xF x compound are the global reaction products. The entire process has ΔG = -19.7 kcal/mol. Two intermediates and two transition states were found. The two transition states correspond to a hydroxyl anion motion toward the phosphorus atom and to a fluoride moving toward the hydroxyl vacant position. From the converged structures, we propose four elementary reactions for the global process. The activation barrier for the rate-limiting step indicates that the degradation reaction of Sarin using brucite is slow. The results of the Sarin deactivation process on brucite show the potential of a layered hydroxide to degrade organophosphorus compounds. © 2011 American Chemical Society.