278 research outputs found

    National industry cluster templates and the structure of industry output dynamics: a stochastic geometry approach

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    Cluster analysis has been widely used in an Input-Output framework, with the main objective of uncover the structure of production, in order to better identify which sectors are strongly connected with each other and choose the key sectors of a national or regional economy. There are many empirical studies determining potential clusters from interindustry flows directly, or from their corresponding technical (demand) or market (supply) coefficients, most of them applying multivariate statistical techniques. In this paper, after identifying clusters this way, and since it may be expected that strongly (interindustry) connected sectors share a similar growth and development path, the structure of sectoral dynamics is uncovered, by means of a stochastic geometry technique based on the correlations of industry outputs in a given period of time. An application is made, using Portuguese input-output data, and the results do not clearly support this expectation.Clusters, Input-output analysis, Industry output dynamics

    National industry cluster templates and the structure of industry output dynamics : a stochastic geometry approach

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    Cluster analysis has been widely used in an Input-Output framework, with the main objective of uncover the structure of production, in order to better identify which sectors are strongly connected with each other and choose the key sectors of a national or regional economy. There are many empirical studies determining potential clusters from interindustry flows directly, or from their corresponding technical (demand) or market (supply) coefficients, most of them applying multivariate statistical techniques. In this paper, after identifying clusters this way, and since it may be expected that strongly (interindustry) connected sectors share a similar growth and development path, the structure of sectoral dynamics is uncovered, by means of a stochastic geometry technique based on the correlations of industry outputs in a given period of time. An application is made, using Portuguese input-output data, and the results do not clearly support this expectation

    Determinação da concentração de CBD-FITC adsorvidos em fibras por análise de imagem

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    Neste trabalho, foi elaborado um programa de processamento e análise de imagem para a determinação da quantidade de CBD-FITC adsorvido em fibras de celulose. Este programa consiste em duas fases em que a primeira se dedica à elaboração da curva de calibração e a segunda à determinação da concentração do CBD-FITC adsorvido. Para a elaboração da curva de calibração é necessário proceder a uma prévia aquisição de amostras de celulose com uma concentração de CBD-FITC espacialmente uniforme e conhecida. A curva de calibração é então obtida com recurso a uma interpolação multivariável por polinómios. Na segunda fase deste programa as imagens das fibras são primeiramente convertidas em concentração, através da curva de calibração obtida, e seguidamente o utilizador pode seleccionar a(s) zona(s) da(s) fibra(s) para a determinação da concentração do CBD-FITC. Esta concentração permitirá conhecer a distribuição dos CBD’s na superfície das fibras de celulose

    Development of a method using image analysis for the measurement of cellulose-binding domains adsorbed onto cellulose fibers

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    The surface concentration of CBD-FITC conjugates, adsorbed on cellulose fibers, was determined by image analysis. The program consists of two scripts, the first dedicated to the elaboration of the calibration curve. The emission of fluorescent light, detected by image analysis, is correlated with the concentration of CBD solutions. This calibration is then used (second script) to determine the concentration of CBDs adsorbed on cellulosic fibers. This method allows the direct estimation of the surface concentration of adsorbed CBDs, which usually is not accurately calculated from depletion studies, since the surface area is hardly known. By observing different spots in the surface of the fibers, site-specific information is obtained. It was verified that the physically heterogeneous fibers exhibit different amounts of adsorbed CBDs.Fundação para a Ciência e a Tecnologia (FCT

    Atenção integrada às doenças prevalentes da infância: eficiência na atenção primária de saúde no Nordeste

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    OBJECTIVE: The Integrated Management of Childhood Illness is a strategy designed to address major causes of child mortality. The aim of this study was to assess the impact of the strategy on the quality of child health care provided at primary facilities. METHODS: Child health quality of care and costs were compared in four states in Northeastern Brazil, in 2001. There were studied 48 health facilities considered to have had stable strategy implementation at least two years before the start of study, with 48 matched comparison facilities in the same states. A single measure of correct management of sick children was used to assess care provided to all sick children. Costs included all resources at the national, state, local and facility levels associated with child health care. RESULTS: Facilities providing strategy-based care had significantly better management of sick children at no additional cost to municipalities relative to the comparison municipalities. At strategy facilities 72% of children were correctly managed compared with 56% in comparison facilities (p=0.001). The cost per child managed correctly was US13.20versusUS13.20 versus US21.05 in the strategy and comparison municipalities, respectively, after standardization for population size. CONCLUSIONS: The strategy improves the efficiency of primary facilities in Northeastern Brazil. It leads to better health outcomes at no extra cost.OBJETIVO: A atenção integrada às doenças prevalentes da infância é uma estratégia desenvolvida para contribuir na redução das principais causas de mortalidade infantil. O objetivo do estudo foi avaliar o impacto da estratégia sobre a saúde infantil. MÉTODOS: Compararam-se a qualidade do atendimento à saúde infantil e os custos associados em quatro estados da região Nordeste do Brasil, em 2001. Foram estudadas 48 unidades de saúde onde havia implementação estável da estratégia por pelo menos dois anos antes do início do estudo e 48 unidades sem (controle) nos mesmos estados. O percentual de crianças doentes atendidas corretamente foi utilizado para avaliar a qualidade da atenção oferecida a crianças doentes. O custo total da atenção à saúde infantil foi avaliado a partir de dados coletados nos níveis nacional, estadual, municipal e de unidade de saúde. RESULTADOS: As unidades que adotam a estratégia obtiveram desempenho significantemente melhor no atendimento de crianças doentes, sem custos adicionais em relação aos municípios sem. Nas unidades com a estratégia, 72% das crianças avaliadas foram atendidas corretamente, comparado com 56% nas unidades controle. O custo por criança atendida corretamente foi de US13.20versusUS13.20 versus US21.05 nos municípios com e sem a estratégia respectivamente, após os ajustes para o tamanho das populações municipais. CONCLUSÕES: A estratégia melhorou a eficiência das unidades de atenção primária de saúde da região estudada. Em unidades de atenção primária com a estratégia, a qualidade do tratamento foi melhor, sem aumento de custos

    Water Pumping System Supplied by a PV Generator and with a Switched Reluctance Motor Using a Drive Based on a Multilevel Converter with Reduced Switches

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    Funding Information: This work was supported by national funds through the FCT—Fundação para a Ciência e a Tecnologia with reference UID/CEC/50021/2020 and UID/EEA/00066/2020. Publisher Copyright: © 2023 by the authors.Pumping systems play a fundamental role in many applications. One of the applications in which these systems are very important is to pump water. However, in the real world context, the use of renewable energies to supply this kind of system becomes essential. Thus, this paper proposes a water pumping system powered by a photovoltaic (PV) generator. In addition, due to its interesting characteristics, such low manufacturing cost, free of rare-earth elements, simple design and robustness for pumping systems, a switched reluctance motor (SRM) is used. The power electronic system to be used in the PV generator and to control the SRM consists of a DC/DC converter with a bipolar output and a multilevel converter. The adopted DC/DC converter uses only one switch, so its topology can be considered as a derivation of the combination of a Zeta converter with a buck–boost converter. Another important aspect is that this converter allows continuous input current, which is desirable for PV panels. The topology selected to control the SRM is a multilevel converter. This proposed topology was adopted with the purpose of reducing the number of power semiconductors. A maximum power point algorithm (MPPT) associated with the DC/DC converter to obtain the maximum power of the PV panels is also proposed. This MPPT will be developed based on the concept of the time derivative of the power and voltage. It will be verified that with the increase in solar irradiance, the generated power will also increase. From this particular case study, it will be verified that changes in the irradiance from 1000 W/m2 to 400 W/m2 will correspond to a change in the motor speed from 1220 rpm to 170 rpm. The characteristics and operation of the proposed system will be verified through several simulation and experimental studies.publishersversionpublishe

    The use of digital photography for the definition of coastal biotopes in Azores.

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    Copyright © Springer Science+Business Media B.V. 2007.Sampling benthic communities usually requires intensive field and lab work which is generally performed by skilled staff. In algal dominated communities, like those on the shores of the Azores, biotope characterization studies focused on the more conspicuous algae categories, thus reducing the skills required for species identification. The present study compares in situ quadrat quantifications done by a skilled reader, with computer based quadrat quantifications using digital photographic records of the same areas read in situ, accomplished by skilled and non-skilled readers. The study was conducted inter- and subtidally at various shore heights/depths. Quantification of algal coverage, both in situ and computer based, used the point to point method with quadrats of 0.25 m × 0.25 m for the intertidal, and 0.50 m × 0.50 m for the subtidal surveys, both subdivided into 36 intersection points. Significant differences were found between in situ readings and computer based readings of photographic records conducted both by experienced and inexperienced readers. Biotopes identified using in situ data and image based data differ both for the subtidal and intertidal

    Incipient Fault Diagnosis of a Grid-Connected T-Type Multilevel Inverter Using Multilayer Perceptron and Walsh Transform

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    Publisher Copyright: © 2023 by the authors.This article deals with fault detection and the classification of incipient and intermittent open-transistor faults in grid-connected three-level T-type inverters. Normally, open-transistor detection algorithms are developed for permanent faults. Nevertheless, the difficulty to detect incipient and intermittent faults is much greater, and appropriate methods are required. This requirement is due to the fact that over time, its repetition may lead to permanent failures that may lead to irreversible degradation. Therefore, the early detection of these failures is very important to ensure the reliability of the system and avoid unscheduled stops. For diagnosing these incipient and intermittent faults, a novel method based on a Walsh transform combined with a multilayer perceptron (MLP)-based classifier is proposed in this paper. This non-classical approach of using the Walsh transform not only allows accurate detections but is also very fast. This last characteristic is very important in these applications due to their practical implementation. The proposed method includes two main steps. First, the acquired AC currents are used by the control system and processed using the Walsh transform. This results in detailed information used to potentially identify open-transistor faults. Then, such information is processed using the MLP to finally determine whether a fault is present or not. Several experiments are conducted with different types of incipient transistor faults to create a relevant dataset.publishersversionpublishe
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