CFD and Experimental Study in the Optimization of an Energy Converter for Low Heads

This paper deals with new design of low head turbines, as feasible solutions to solve the lack of energy in rural and remote areas, or to provide energy from urban water pipe systems. Propeller turbines are then the subject of this research because they are suitable for small heads, discharges with little variability, easy to manufacture and with low costs associated. Hence, the aims are the design of quite simple tubular propeller turbines and the analysis of hydrodynamic behaviour for different number and configuration of blades, based on CFD analyses and experimental tests development. An advanced hydrodynamic code based on the finite volume method, as well as blades configuration and mesh specific models are used for the impeller and the turbine design. The blade geometry is optimized using mathematical formulations and experimental results, concerning the possible range of operation under best efficiency conditions. Performance curves are obtained for typical characteristic parameters allowing comparisons between CFD and experimental results. Based on the similarity theory applied to turbomachines it is possible to evaluate the hydrodynamic behaviour through a tubular propeller for different sizes, in a scale model application

Distinguishing sequences for partially specified FSMs

Distinguishing Sequences (DSs) are used inmany Finite State Machine (FSM) based test techniques. Although Partially Specified FSMs (PSFSMs) generalise FSMs, the computational complexity of constructing Adaptive and Preset DSs (ADSs/PDSs) for PSFSMs has not been addressed. This paper shows that it is possible to check the existence of an ADS in polynomial time but the corresponding problem for PDSs is PSPACE-complete. We also report on the results of experiments with benchmarks and over 8 * 106 PSFSMs. © 2014 Springer International Publishing

Curva de crescimento e valor nutritivo de capim-elefante, cv. Porto Rico-534, na região de Belém-Pará.

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Cellulose nanocrystals from fibers of Macauba (Acrocomia Aculeata) and Gravata (Bromelia Balansae) from Brazilian Pantanal.

Cellulose nanocrystals (CNC) were obtained from macauba and gravata fibers. Macauba (or Bocaiuva) is a palm tree found throughout most of Brazil and Gravata is an abundant kind of bromeliab with 1-2m long leaves, found in Brazilian Pantanal and Cerrado. The raw fibers of both fibers were mercerized with NaOH solutions and bleached; they were then submitted to acid hydrolysis using H2SO4 at 45 ?C, varying the hydrolysis time from 15 up to 75 min. The fibers were analyzed by X-ray diffraction (XRD), FTIR Spectroscopy, scanning electron microscopy (SEM) and thermal stability by thermogravimetric analysis (TG). XRD patterns did not present changes in the crystal structure of cellulose after mercerization, but it was observed a decrease of hemicellulose and lignin contents, and consequently an increase of cellulose content with the increase of NaOH solution concentration in the mercerization. After acid hydrolysis, the cellulose nanocrystals (CNC) were also analyzed by transmission electron microscopy (TEM) which showed an acicular or rod-like aspect and nanometric dimensions of CNC from both fibers, but the higher values of aspect ratio (L/D) were found on CNC obtained from gravata after 45 min of acid hydrolysis. The mercerization and subsequent bleaching of fibers influenced the crystallinity index and thermal stability of the resulting CNC, but their properties are mainly influenced by the hydrolysis time, i. e., there is an increase in crystallinity and thermal stability up to 45 min of hydrolysis, after this time, both properties decrease, probably due to the cellulose degradation by the sulfuric acid

Can lightning be a noise source for a spherical gravitational wave antenna?

The detection of gravitational waves is a very active research field at the moment. In Brazil the gravitational wave detector is called Mario SCHENBERG. Due to its high sensitivity it is necessary to model mathematically all known noise sources so that digital filters can be developed that maximize the signal-to-noise ratio. One of the noise sources that must be considered are the disturbances caused by electromagnetic pulses due to lightning close to the experiment. Such disturbances may influence the vibrations of the antenna's normal modes and mask possible gravitational wave signals. In this work we model the interaction between lightning and SCHENBERG antenna and calculate the intensity of the noise due to a close lightning stroke in the detected signal. We find that the noise generated does not disturb the experiment significantly.Comment: 5 pages, 6 figure

Monitoramento da murcha do abacaxizeiro associada à cochonilha Dysmicoccus brevipes em áreas de sistema de produção integrada no Estado do Tocantins - ciclo 2010.

No Brasil, cultiva-se o abacaxizeiro, Ananas comosus (L) na maioria das regiões ,sendo a 'Pérola' a cultivar mais plantada. Apesar de seu aspecto rústico, essa bromeliácea, em uma produção comercial, exige tratos culturais e fitossanitários rigorosos, para evitar problemas como a murcha que está associada à cochonilha Dysmicoccus brevipes Cockerell (1893) (Hemiptera: Pseudococcidae), cujas perdas na produção, em cultivares suscetíveis, podem ultrapassar os 80% (SANCHES, 2005). O mercado interno é ainda o mais visado pelos produtores de abacaxi, sendo a aquisição ou venda de mudas entre produtores uma prática muito comum que, propicia a dispersão desse inseto de uma propriedade para outra ou de uma região para outra. O Sistema de Produção Integrada de Abacaxi é uma prática de apoio aos produtores para atender as exigências crescentes do mercado consumidor quanto à produção de alimentos seguros. Esse sistema é baseado nas boas práticas agrícolas traduzindo em valorização do ser humano, conservação do meio ambiente (solo e água), melhoria da qualidade de vida dos produtores rurais, respeito à legislação trabalhista e segurança do trabalhador.bitstream/item/31028/1/documentos-193ID27590.pd