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Sampaio J.C.,Sao Paulo State University | Da Silva Fernandes S.,IEF | Formiga J.K.,FATEC
Advances in the Astronautical Sciences | Year: 2013

A semi-analytical approach is proposed to study resonances effects on the orbital motion of artificial satellites or space debris orbiting the Earth. Applying successive Mathieu transformations, the order of dynamical system is reduced and the final system is solved by numerical integration. In the simplified dynamical model, we can choose the resonance to be considered as critical angle. Simulations are presented showing the variations of the orbital elements of bodies orbiting in the neighbourhood of the 2:1, 14:1 and 15:1 resonance condition. The half-width of the separatrix is calculated through a linearized model which describes the behavior of the dynamical system in a neighborhood of each critical angle. A semi-analytical approach is proposed to study resonances effects on the orbital motion of artificial satellites or space debris orbiting the Earth. Applying successive Mathieu transformations, the order of dynamical system is reduced and the final system is solved by numerical integration. In the simplified dynamical model, we can choose the resonance to be considered as critical angle. Simulations are presented showing the variations of the orbital elements of bodies orbiting in the neighbourhood of the 2:1, 14:1 and 15:1 resonance condition. The half-width of the separatrix is calculated through a linearized model which describes the behavior of the dynamical system in a neighborhood of each critical angle. © 2013 2013 California Institute of Technology. Source


The changes in the successional structure and floristic diversity of a fragment of Mixed Rain Forest, located on Irati National Forest, Parana State, were monitored over six years. Data were collected in an area of 25 ha, measured in 2002, 2005 and 2008 and on the three occasions, all trees with DBH ≥ 10 cm were measured, numbered and identified. To study the successional structure the trees were classified into four ecophysiological groups: a) pioneer; b) early secondary; c) late secondary and d) no characterization. The floristic diversity was evaluated using the Shannon (H'), Simpson (D') and Pielou's Evenness (J') indices. The analyses showed increase from 89 to 90% in the number of individuals belonging to the category of secondary species, as well as an increase of 4.46% in the number of species and genera of 3.80%, indicating that the forest is more diverse (richness) and structured. The main factor for this result is the advanced stage of succession which favor the emergence of new species and helps to reduce the number of individuals of dominant species as corroborated by the values of the indices of Shannon (H'=3.55 and 3.57), Simpson (D'=0.044 and 0.043) and Pielou's Evenness (J'=75%) during the period. Source


Stepka T.F.,UNICENTRO | Dias A.N.,UNICENTRO | Filho A.F.,Federal University of Parana | Machado S.A.,Federal University of Parana | Sawczuk A.R.,IEF
Floresta | Year: 2012

Increment diameter models for Araucaria angustifolia from an Ombrophyllous Mixed Forest in the center-south of Paraná. This research aims to test the viability of the hypothesis of adjustment of models capable of predicting diameter increment for Araucaria angustifolia from an Ombrophyllous Mixed Forest in the National Forest of Irati, Parana State using several data stratification methods. In this forest, twenty-five permanent plots of one hectare each (100 m × 100 m) were installed and measured in 2002, being remeasured in 2005 and 2008. All trees with Diameter at Breast Height (DBH) greater than or equal to 10 cm were numbered, measured and identified. 1039 Araucaria trees were used in the adjustment of 10 mathematical models. These araucaria trees were measured three times (2002, 2005 and 2008) and the annual periodic increment was determined. The results revealed that data stratification, in some cases, improved adjustments for the models, with more significant results with increments gathered in diameter classes. However, the great variability of the increments of the focused species revealed that the stratification data hypothesis cannot be improved, and should be cast aside. Source


Colli A.,IEF | Vital B.R.,Federal University of Vicosa | Carneiro A.C.O.,Federal University of Vicosa | Silva J.C.,Federal University of Vicosa | And 2 more authors.
Revista Arvore | Year: 2010

This work had as its objective to determine the properties of particleboards fabricated with paricá particles (Schyzolobium amazonicum Huber ex. Ducke), with increasing proportions of coconut fibers (Coconuts nucifera L.). Boards were fabricated with 6 or 8% of urea-formaldehyde adhesive. Particleboard mean density was equal to 360 kg/m3. The addition of coconut fibers didn't affected boards' dimensional stability, higrospicidity, water absorption capability. However it increased its mechanical properties. The addition of 8% of adhesive improved all board properties. Source


Bideaud A.,CNRS Neel Institute | Belier B.,IEF | Benoit A.,CNRS Neel Institute | Berge L.,French National Center for Scientific Research | And 6 more authors.
Experimental Astronomy | Year: 2011

Microbolometers are at present the most sensitive detectors for mm and sub-mm Astronomy. They are in use in most of the present instruments in that bandwidth. We have developed filled arrays of NbSi-based planar antenna coupled microbolometers. The fabrication details are given, together with characterization of the NbSi thermometers and optical results. The optical performances are potentially good for ground-based mm-wave astronomy applications, while the overall detectors performances are limited by low-frequency excess noise in the thermometric NbSi high-impedance sensors (Anderson insulator). © 2011 Springer Science+Business Media B.V. Source

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