A Influência da Referência de Tensão na Avaliação de Indicadores de Qualidade de Energia

This paper discusses the importance of the voltage referential for power quality monitoring and power systempsilas instrumentation. Considering the operating conditions of simple power circuits, it will be demonstrated that an incorrect choice of the voltages referential may result in erroneous quantification of some power quality indices, especially in three-phase four wire circuits. The use of a virtual reference point and the neutral conductor as reference have been considered and the simulation results confirm the influence of the voltage reference selection in the evaluation of total harmonic distortion, unbalance factors and voltage sags. Finally a way of linking both methods will be discussed by means of Blakesleypsilas theorem. © Copyright 2010 IEEE - All Rights Reserved.

Custo de produção e indicadores de rentabilidade da cultura do milho safrinha

The objective of this study was to evaluate the production cost and profitability of the second season corn crop in the Medio Paranapanema region, São Paulo State Brazil, under two technological levels (middle and high technology), crop 2008/2009, and compare the results with the 2006/2007 agricultural year. Effective and total operational cost as well as five profitability indicators were used. It was concluded that the high technology production cost for corn crop (direct seedling, sowing during the recommended period, use of simple hybrid seed, application of side-dressing fertilization, and treatment of seeds with different insecticides) was superior to the middle technology production cost (direct seedling, sowing after the recommended time, use of double hybrid seed, and no side-dressing fertilization). However, the average cost was inferior (US$ 8.5), due to a higher yield (4 t). The high technology corn crop was profitable (gross income and profitability index of 14% and 12%, respectively). For the middle technology crop, profitability indexes pointed out that the cropping system needs to be reevaluated by technicians and research institutions, regarding the adequate technical recommendations. Profitability indexes decreased considerably in both cropping systems. It was verified that, in relation to the 2006/2007 harvest period, the total operational cost increased for both technologies, mainly because of the increase of supplies prices.

Diferentes procedimentos na determinação de indicadores internos para estimativa de produção fecal e fluxo duodenal de matéria seca em bovinos

Times of in situ incubation (144 and 288h) for determination of internal markers IADF and INDF and the effects of differents procedures (wash or not the nylon bag every 72h incubation) was evaluated in samples of diet, duodenal digesta and cattle feces. The duodenal flow dry matter and fecal production utilizing the internal markers to compare with the external marker chromium oxide there was estimated. The animals were fed with sorgum silage, concentrate or urea. In this experiment, a latin square design was used, in a factorial scheme (two times of incubation × two processing nylon bag). No was observed effect of the incubation time or processing in the internal markers INDF and IADF concentration and the in situ incubation after 144h is adequate to reproduce the indigestible markers fraction in samples. For fecal production estimation, the external marker chromium oxide presented similar result (1.26 kg day-1) as the total fecal collection (1.49 kg day-1). Both the internal markers overestimate the duodenal flow dry matter when compared with the external marker chromium oxide.

Diversidade de microrganismos indicadores utilizados na avaliação da contaminação fecal de areias de praias recreacionais marinhas: Estado atual do conhecimento e perspectivas

Although the quality of sea recreational waters is already monitored by programs implanted in some Brazilian states, including the State São Paulo, little attention has been given to beach sands, which have been disregarded from the point of view of public health. However, this panorama is changing in recent years due to an increasing number of cases of mycoses and bacterial infections affecting people who frequent beaches and use sands as recreation places. This has caused greater concerns with the contamination of this environment, also measurable by the increase of the number of scientific works on sediments and recreational beach sands microbiota. Currently one knows that in general these sediments contain more microorganisms than the water and are therefore potential sources of contamination of human beings by pathogenic microorganisms. The results of works carried through in some countries are worrying, and have demonstrated the necessity of establishing standards and limits so that monitoring programs of the microbiological quality of beach sands are implanted. Such concern is especially high in Brazil, a country of a tropical climate where thousands of beaches, used for recreation, extend for almost eight thousand kilometers of the coast. In the context of Baixada Santista, studies carried through have shown that in certain situations beach sands can contain more microorganisms than waters and may be a risk to the health of users.

Indicadores na estimativa do fluxo de digesta em bovinos de corte

single and double marker methods were compared in seven Nellore steers with average body weight 250 kg, and previously canullated in the rumen and duodenum. The animals were fitted with continuous-infusion pump that administered CoEDTA solutions intraruminally. In addition, a capsule containing Cr 2O 3, and other, containing external n-alkanes C 32, C 36 were inserted into the rumen of each steer. Internal markers indigestible neutral-detergent fiber and acid-detergent fiber (iNDF and iADF after 144 h in situ incubation) and internal n-alkanes C 31, C 33, C 35 were components of the diet. Steers were fed with palisade grass (Brachiaria brizantha cv. marandu) in two age of regrowth, 30 and 60 days. The duodenal flow experimental design was a factorial 2×2×12 while omasal experimental design was a factorial 2×2×4. Markers iNDF, CoEDTA and the combination Co+iNDF were efficacious to estimate duodenal dry matter flow whereas iNDF, iADF and the Co+iADF combination were all efficacious to predict omasal dry matter flow. In conclusion, the double marker method for estimation of omasal and duodenal dry matter flow was the most appropriate considering the ruminal fiber digestibility.

Fezes equina como fonte de inóculo na obtenção de indicadores indigestíveis para estimar a digestibilidade em equinos

Four castrated horses were utilized in randomized blocks experimental design. The objective was to study the in vitro acquirement of indigestible fiber, neutral detergent fiber (NDFi) and acid detergent fiber (ADFi), using as inoculum source rumen fluid (RF) or horse feces (HF), to estimate the nutrient digestibility (ND) in horses. Treatments consisted of direct method by total feces collection (TC) and indirect method either by the use of NDFi or ADF by the use of LR or HF as inocula source. The first essay was done with horses fed coast-cross hay exclusively, while for the essay two, the horses were fed of 70% of coast-cross hay and 30% corn grain. For the essay 1, ADFi-HF presented the best marker recuperation rate (RR) (103.67%), being similar to control (TC), while NDFi-RF and ADFi-RF resulted in lower RR (P<0.05), 83.43 and 88.28%, respectively. The ND was adequately estimated by NDFi-HF and ADFi-HF. On the second essay there were no significant effects of the marker type, as well as for the indigestible marker acquirement method, for the marker RR (average value of 101%). The ND was adequately predicted by the ADFi obtained for both innocula source and NDFi obtained by the use of HF as inoculum, for horses fed a mixed diet. It can be concluded that horse feces may be used as inoculum source for the acquirement of NDFi and ADFi in vitro for digestibility determination on horses fed coastcross hay exclusively, as well as for horses fed a mixed diet.