A COMPARATIVE STUDY FOR PROPELLER BLADE DESIGN

This work presents a comparative study between two propeller design methods for aeronautical application, with emphasis on its main element, the blade. The first method is an empirical approach based on graphical distribution of design parameters of a propeller and consists on a sequence of steps which starts from defined value for parameters like flight speed, propeller RPM, etc; with a view to obtain others dimensional parameters (diameter, twisting angle, etc) for a propeller to be used on a general aviation aircraft, with the goal to achieve certain performance target. According to the author of this method, the design of a propeller should be seen more as an art rather than exact science. The second method is well known by the aeronautical industry and called “method or theory of blade element”. This theory consider a propeller blade as a twisted wing, for which the quantities of interest to be obtained are the aerodynamics reactions, lift and drag, which are a function of the airfoil characteristics (treated as aerodynamic coefficients, cl for lift and cd for drag) for each section along blades length, twist angle, Mach, etc. For obtaining the propeller value of interest, the number of blades must also be considered. As an application for the study it was used a tri-blade propeller which equips an airplane for general aviation, that can carry 4 occupants flying at 170 Knots. The first aim of this study was to compare the results provided by the empirical method against the BET (Blade Element Theory). A secondary objective was to extend the empirical method in the design of a propeller for use on a closed circuit wind tunnel, once verified the consistency of obtained results as aimed on the first part of this study. Although the results were favorable, showing that both methods provide similar results, the study showed that the empirical method is not valid for operating and constructive conditions set for conditions like the defined for this wind tunnel, once for this type of application, the design parameters extrapolates the minimum and maximum limits established in the empirical method, providing extremely inconsistent results

Follicular Fluid redox involvement for ovarian follicle growth

As the human ovarian follicle enlarges in the course of a regular cycle or following controlled ovarian stimulation, the changes in its structure reveal the oocyte environment composed of cumulus oophorus cells and the follicular fluid (FF).In contrast to the dynamic nature of cells, the fluid compartment appears as a reservoir rich in biomolecules. In some aspects, it is similar to the plasma, but it also exhibits differences that likely relate to its specific localization around the oocyte. The chemical composition indicates that the follicular fluid is able to detect and buffer excessive amounts of reactive oxygen species, employing a variety of antioxidants, some of them components of the intracellular milieu.An important part is played by albumin through specific cysteine residues. But the fluid contains other molecules whose cysteine residues may be involved in sensing and buffering the local oxidative conditions. How these molecules are recruited and regulated to intervene such process is unknown but it is a critical issue in reproduction.In fact, important proteins in the FF, that regulate follicle growth and oocyte quality, exhibit cysteine residues at specific points, whose untoward oxidation would result in functional loss. Therefore, preservation of controlled oxidative conditions in the FF is a requirement for the fine-tuned oocyte maturation process. In contrast, its disturbance enhances the susceptibility to the establishment of reproductive disorders that would require the intervention of reproductive medicine technology.info:eu-repo/semantics/publishedVersio

Produção de feno no Semi-Árido.

Producão de feno a partir de grarníneas e legurninosas; Algumas árvores e arbustos nativos e exóticos adaptados ao Semi-Árido com potencial forrageiro; Faveira-de-bolota (Parkia platycephala); Leucena(Leucaena leucocephala); Feijão-guandu(Cajanus cajan); Sabiá(Mimosa caesalpiniaefolia); Pau-ferro(Caesalpinia ferrea); Jurerninha(Desmanthus virgatus); Mororó (Bauhinia cheilantha); Camaratuba(Cratylia argentea); Algaroba(Prosopis juliflora); Gliricídia(Gliricidia sepium); Juazeiro(Ziziphus spp.); Maniçoba(Mnihot pseudo glaziovii); Algodão-de-seda(Calotropis procera); Mandioca, macaxeira(Manihot esculenta); Mata-pasto(Senna obtusifolia); Bordão-de-velho(Samanea saman); Jurema-preta(Mimosa tenuiflora).bitstream/item/35908/1/Doc149.pd