Joelma M. Ferreira

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The dependence of the dynamical response of spectral hole burning (SHB) of an erbium-doped fiber amplifier (EDFA) on temperature is investigated. Experimental results show that gain variations decrease with increasing temperature. The dependence of the transition time on temperature is weak with a trend to larger values at higher temperatures. We also(More)
Novel aluminised E-glass fibre reinforced unsaturated polyester composites, originally formulated for enhanced thermal and electrical shielding properties were evaluated in terms of their thermal performance. The thermal degradation of these specimens was analysed using a thermogravimetric analyser (TGA). The samples were heated from ambient temperature to(More)
The climatic fluctuations during glaciations have affected differently arctic and temperate species. In the northern hemisphere, cooling periods induced the expansion of many arctic species to the south, while temperate species were forced to retract in southern refugia. Consequently, in some areas the alternation of these species set the conditions for(More)
The equations ruling the thermal equilibrium along coronal loops on rapidly rotating solar-type stars are solved. The particular case of loops with lengths comparable or greater than a stellar radius is studied. Depending on the base pressure, it is found that hot loops can exist either with very high coronal temperature (T∼107 K) or with a more solar like(More)
This paper is a study of the applicability of fracture surface roughness measurements to identify the crack propagation mode in nickel base superalloys (transgranular, intergranular or mixed). The results obtained indicated that this technique can be used as an alternative or as a complement to standard fractography. The best roughness parameters for(More)
The present work aims to evaluate on a bench scale, the effects of nitrogen and phosphorous nutrient source concentrations in vinegar production, a process that is used by small scale industries in the State of Paraiba. The response surface methodology has been utilized for modeling and optimization of the fermentation process. Initially a 23 complete(More)
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