950 resultados para protection systems


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El documento hace una revisión de las principales fuentes de protección social que hay en Colombia y las características de los sistemas de protección de otros países. Se encuentra que gran parte de lo que se conoce como gasto social se destina al tema pensional y que los resultados de los fondos de solidaridad son muy pequeños frente a la autoprotección de los hogares. Se propone tener en cuenta los esfuerzos individuales y privados que hay en Colombia al diseñar un sistema de protección social, pues de lo contrario se estarían desincentivando estos esfuerzos.

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La importància que els acolliments en família extensa han assolit en la darrera dècada dins dels sistemes de protecció infantil en la major part dels països occidentals, contrasta tant amb l'escassa i recent investigació científica com amb els pocs recursos destinats als infants i adolescents que hi són acollits. L'objectiu general de la tesi ha estat el d'aprofundir en el coneixement i comprensió d'aquest fenomen dins del sistema de protecció infantil a Catalunya. La present recerca s'ha realitzat recollint els punts de vista dels tres grans conjunts d'agents socials implicats: els acollidors, els infants i adolescents acollits i els professionals dels EAIAs (Equips d'Atenció a la Infància i Adolescència) que els atenen; explorant les seves percepcions, avaluacions, expectatives i satisfaccions referides a l'acolliment. Així mateix, l'estudi s'ha dut a terme amb una metodologia de disseny mixt, recollint dades quantitatives i qualitatives. Els resultats mostrats ens suggereixen un seguit d'implicacions per a la pràctica i ens obren nous reptes de recerca, per tal de promoure, en definitiva, la qualitat de vida dels nois i noies i dels seus acollidors.

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We have analyzed the extent of regulation by the nitric oxide (NO)-sensitive repressor NsrR from Neisseria meningitidis MC58, using microarray analysis. Target genes that appeared to be regulated by NsrR, based on a comparison between an nsrR mutant and a wild-type strain, were further investigated by quantitative real-time PCR, revealing a very compact set of genes, as follows: norB (encoding NO reductase), dnrN (encoding a protein putatively involved in the repair of nitrosative damage to iron-sulfur clusters), aniA (encoding nitrite reductase), nirV (a putative nitrite reductase assembly protein), and mobA (a gene associated with molybdenum metabolism in other species but with a frame shift in N. meningitidis). In all cases, NsrR acts as a repressor. The NO protection systems norB and dnrN are regulated by NO in an NsrR-dependent manner, whereas the NO protection system cytochrome c′ (encoded by cycP) is not controlled by NO or NsrR, indicating that N. meningitidis expresses both constitutive and inducible NO protection systems. In addition, we present evidence to show that the anaerobic response regulator FNR is also sensitive to NO but less so than NsrR, resulting in complex regulation of promoters such as aniA, which is controlled by both FNR and NsrR: aniA was found to be maximally induced by intermediate NO concentrations, consistent with a regulatory system that allows expression during denitrification (in which NO accumulates) but is down-regulated as NO approaches toxic concentrations.

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Most algorithms for state estimation based on the classical model are just adequate for use in transmission networks. Few algorithms were developed specifically for distribution systems, probably because of the little amount of data available in real time. Most overhead feeders possess just current and voltage measurements at the middle voltage bus-bar at the substation. In this way, classical algorithms are of difficult implementation, even considering off-line acquired data as pseudo-measurements. However, the necessity of automating the operation of distribution networks, mainly in regard to the selectivity of protection systems, as well to implement possibilities of load transfer maneuvers, is changing the network planning policy. In this way, some equipments incorporating telemetry and command modules have been installed in order to improve operational features, and so increasing the amount of measurement data available in real-time in the System Operation Center (SOC). This encourages the development of a state estimator model, involving real-time information and pseudo-measurements of loads, that are built from typical power factors and utilization factors (demand factors) of distribution transformers. This work reports about the development of a new state estimation method, specific for radial distribution systems. The main algorithm of the method is based on the power summation load flow. The estimation is carried out piecewise, section by section of the feeder, going from the substation to the terminal nodes. For each section, a measurement model is built, resulting in a nonlinear overdetermined equations set, whose solution is achieved by the Gaussian normal equation. The estimated variables of a section are used as pseudo-measurements for the next section. In general, a measurement set for a generic section consists of pseudo-measurements of power flows and nodal voltages obtained from the previous section or measurements in real-time, if they exist -, besides pseudomeasurements of injected powers for the power summations, whose functions are the load flow equations, assuming that the network can be represented by its single-phase equivalent. The great advantage of the algorithm is its simplicity and low computational effort. Moreover, the algorithm is very efficient, in regard to the accuracy of the estimated values. Besides the power summation state estimator, this work shows how other algorithms could be adapted to provide state estimation of middle voltage substations and networks, namely Schweppes method and an algorithm based on current proportionality, that is usually adopted for network planning tasks. Both estimators were implemented not only as alternatives for the proposed method, but also looking for getting results that give support for its validation. Once in most cases no power measurement is performed at beginning of the feeder and this is required for implementing the power summation estimations method, a new algorithm for estimating the network variables at the middle voltage bus-bar was also developed

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The objectives of the IPP Project-Periodic Inspection on Crop Sprayers-are to develop methods for sprayer certification, analyze quality on spray operation, propose an inspection system for crop sprayers in Brazil, improve environmental quality on spray operation, and reduce costs on chemical control for plant protection systems. Periodic inspections on crop sprayers are performed in several countries and are compulsory in most of them, and it is becoming an important tool for improvement and optimization of use of chemicals. The IPP Project in Brazil is funded by FAPESP-Fundação de Amparo a Pesquisa do Estado de São Paulo. The results so far showed that all the sprayers presented failures. However, most of them could be approved with minor services. As an example, 56.6% of the sprayers with more than 2 years of use presented leaks, 47% of them had damaged hoses and 80.5% presented bad tips (nozzles). These results indicate the need for better procedures of use and maintenance of sprayers, justifying the periodic inspection system.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In this paper, an expert and interactive system for developing protection system for overhead and radial distribution feeders is proposed. In this system the protective devices can be allocated through heuristic and an optimized way. In the latter one, the placement problem is modeled as a mixed integer non-linear programming, which is solved by genetic algorithm (GA). Using information stored in a database as well as a knowledge base, the computational system is able to obtain excellent conditions of selectivity and coordination for improving the feeder reliability indices. Tests for assessment of the algorithm efficiency were carried out using a real-life 660-nodes feeder. © 2006 IEEE.

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Includes bibliography

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Incluye Bibliografía

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Incluye bibliografía

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Incluye bibliografía

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Incluye bibliografía

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Incluye bibliografía