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Henrique Costa Dias M.,Military Institute of Engineering of Rio de Janeiro | Carlos Araujo Dos Santos J.,Military Institute of Engineering of Rio de Janeiro | De Magalhaes Ottoni Da Silva G.,Centro Tecnologico Do Exercito CTEx
IEEE Latin America Transactions | Year: 2011

This work addresses the main features of a coverage planning algorithm for VHF/UHF low power radio communications systems operating at urban sites, in which special attention was given to mixed terrain clutter transitions. Most of the available commercial prediction tools adopt rough solutions to some problems derived from the use of semi-empirical models with geographical databases. The influence of mixed-path terrains and the path loss due to dense vegetation are typical related examples of usually overlooked aspects. The developed code is based on Hatas semi-empirical approach with additional point-to-point adjusts, and includes specific procedures for those two aspects. It has been developed as Matlab routines, which were evaluated comparing its outputs to the ones obtained from the use of a commercial planning tool. Results were coherent with the specific features of the site chosen for the analysis. © 2011 IEEE.

Ribeiro J.,Federal Rural University of Rio de Janeiro | Cavaglieri L.,National University of Rio Cuarto | Cavaglieri L.,CONICET | Vital H.,Centro Tecnologico Do Exercito CTEx | And 10 more authors.
Radiation Physics and Chemistry | Year: 2011

The aim of this work was to study the effect of gamma radiation (2kGy) on Aspergillus flavus and Aspergillus ochraceus ultrastructure. Moreover, the influence on aflatoxin B1 and ochratoxin A production was also observed. Irradiated A. flavus strain showed a dull orangish colony while control strain showed the typical green color. Minor differences were observed on stipes, metulae and conidia size between control and irradiated A. flavus and A. ochraceus strains. Irradiated fungi showed ultrastructural changes on cell wall, plasmalema and cytoplasm levels. The levels of mycotoxins produced by irradiated strains were two times greater than those produced by control strains. Successive transferences of irradiated strains on malt extract agar allowed the fungus to recuperate morphological characteristics. Although minor changes in the fungal morphology were observed, ultrastructural changes at cell wall level and the increase of mycotoxin production ability were observed. Inappropriate storage of irradiated food and feed would allow the development of potentially more toxicogenic fungal propagules. © 2011.

Cardoso M.H.W.M.,Instituto Nacional Of Controle Of Qualidade Em Saude | de Nobrega A.W.,Instituto Nacional Of Controle Of Qualidade Em Saude | Vital H.C.,Centro Tecnologico Do Exercito CTEx | Abrantes S.M.P.,Instituto Nacional Of Controle Of Qualidade Em Saude
Ciencia e Tecnologia de Alimentos | Year: 2010

This research presents the results of stability studies regarding the production of certified reference materials. The residual concentration levels of four pesticides, namely γ-HCH, fenitrothion, chlorpyrifos, and procymidone were investigated. Pasteurization combined with gamma irradiation was used to maintain the integrity of the mixture tested as a reference material candidate. The pulp was prepared and split into two parts. Each part was then spiked with those pesticides in the concentration range of 0.1 to 0.2 mg.kg-1 in tomato pulp. One of them was submitted to pasteurization at 90 °C for 4 minutes after being homogenized, and the other was irradiated with a gamma dose of 2.0 kGy. The material stability and the corresponding uncertainty during the period of time evaluated were determined using regression analysis and ANOVA. The results indicated that the dose of 2.0 kGy was appropriated for the conservation of tomato pulp spiked with the four aforementioned pesticides.

de Assis L.P.G.,Federal Rural University of Rio de Janeiro | de Assis L.P.G.,Brazilian Center for Research in Physics (CBPF) | Gaete P.,Federico Santa Maria Technical University | Helayel-Neto J.A.,Brazilian Center for Research in Physics (CBPF) | And 2 more authors.
International Journal of Theoretical Physics | Year: 2012

In the framework of three-dimensional Born-Infeld Electrodynamics, we pursue an investigation of the consequences of the space-time dimensionality on the existence of magnetostatic fields generated by electric charges at rest in an inertial frame, which are present in its four-dimensional version. Our analysis reveals interesting features of the model. In fact, a magnetostatic field associated with an electric charge at rest does not appear in this case. Interestingly, the addition of the topological term (Chern-Simons) to Born-Infeld Electrodynamics yields the appearance of the magnetostatic field. We also contemplate the fields associated to the would-be-magnetic monopole in three dimensions. © 2011 Springer Science+Business Media, LLC.

Furtado Filho A.A.M.,Centro Tecnologico Do Exercito CTEx | Gomes A.S.,Federal University of Rio de Janeiro
International Journal of Hydrogen Energy | Year: 2012

Composite sulfonated bisphenol-A-polysulfone (SPSF) based PEMs, containing tungstophosphoric acid (TPA) and modified by electron beam (EB) irradiation with doses of 50 and 100 kGy, were prepared and characterized by a number of physico-chemical methods. The probability of the cross-linking was increased by post treatment of the irradiated membranes at 180 °C for 8 h into a vacuum oven. The cross-linking strongly affected membrane properties, reducing their swelling, but at the same time decreasing their proton conductivity. The proton conductivity of the membranes was measured by a two electrode ac impedance technique using a frequency response analyzer. The PEMs performance was tested in H 2/O 2 fuel cell (FC) and found to approach that of Nafion ® 117 commercial PEM at the same conditions. The PEMs composite stability was adequate at least for 2 days, during which no degradation of the performance was observed. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

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