1000 resultados para Coeficiente troca gasosa
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Tese de dout., Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve, 1995
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Objetivo: Determinar la prevalencia de anemia en escolares de 6 a 12 años del área urbana de la ciudad de Cuenca y su relación con el coeficiente intelectual. Diseño: Se realizó un estudio transversal durante los meses de noviembre y diciembre de 2007 en el área urbana de la ciudad de Cuenca del austro ecuatoriano. Se eligieron 4 escuelas aleatoriamente hasta completar el tamaño muestral de 261 niños. Se recogieron los datos antropométricos (peso y talla); se determinaron los valores de hemoglobina y se realizó un test psicológico. Resultados: La prevalencia general de anemia fue de 9,6, y de los escolares afectados el 77,77tenían anemia por déficit de hierro. El parámetro antropométrico que mostró la mayor asociación con la presencia de anemia fue la relación entre la estatura y la edad (OR: 1,35 IC: 1,33 - 9,21). La variable anemia se asoció significativamente al coeficiente intelectual en un 17. El porcentaje de niños con desnutrición crónica fue de 11,9y riesgo de desnutrición del 15,7El tipo de escuela se asoció levemente al coeficiente intelectual (p= 0.03) (OR: 1,87 IC: 1,05 - 3,39). No se encontró ninguna relación entre la prevalencia de anemia por un lado, y el sexo por el otro. Tampoco existió relación entre la variable sexo y el coeficiente intelectual. Conclusiones: La anemia en general y la anemia ferropénica en particular, no constituyen un problema de salud pública en la población estudiada. Los escolares con talla alta tienen menor riesgo de desarrollar anemia. La anemia se asoció significativamente al coeficiente intelectual
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A Constituição Federal de 1988 e o Estatuto da Cidade estabelecem o Plano Diretor como instrumento básico da política de ordenamento territorial, tendo como princípio fundamental o cumprimento da função social da propriedade e do direito à cidade. Na perspectiva de adequação às diretrizes e objetivos da política urbana estabelecidos em 1988, o município de Natal elaborou os Planos Diretores de 1994 e 2007, definindo instrumentos e parâmetros de regulação do uso e ocupação do solo possíveis de assegurar o cumprimento da função social da propriedade urbana e de gerar subsídios ao planejamento e à gestão da cidade. Apesar de Natal ter sido um dos municípios brasileiros pioneiros na adoção desses princ pios, antecipando e incorporando os instrumentos que em 2001 viriam a ser definidos no Estatuto da Cidade, identifica-se que alguns desses instrumentos e parâmetros direcionados à regulação do uso e ocupação do solo não tiveram sua aplicação plena, a exemplo do mecanismo de acompanhamento e controle dado pelo Estoque de Área Edificável e da Densidade, que foi substituída pelo Coeficiente de Aproveitamento no Plano Diretor de 2007. Questionando esse procedimento, busca-se na presente pesquisa investigar de que maneira essa substituição do parâmetro densidade pelo coeficiente de aproveitamento influenciou na capacidade da gestão pública de regular os processos de uso e ocupação do solo, de forma a adequar a sua intensificação ao suporte da infraestrutura instalada. Foram tomadas como referência teórico-conceitual as contribuições sobre a prática de planejamento urbano no Brasil, nos marcos do ideário da reforma urbana, com destaque para as reflexõe s de Flávio Villaça, Orlando Alves Santos Junior e Daniel Todtmann Montandon, Luiz César de Q. Ribeiro, Raquel Rolnik, Ermínia Maricato, Laura Machado de Bueno e Renato Cymbalista, José Roberto Bassul e Carlos F. Lago Burnett, e, com relação aos parâmetros de controle urbanístico, o estudo identifica as diferentes abordagens sobre a densidade urbana e o coeficiente de aproveitamento com base nas reflexões de Claudio Acioly Jr., Forbes Davidson, Juan Luis Mascaró, Ricardo Ojima, Marcelo de Souza, José Rámon Navarro Vera e Armando Ortuño Padilla, Nestor Goulart Reis, Marta Dora Grostein e Susana Ricardo Alves. Como conclusão, discute-se a hipótese formulada, inicialmente, de que a mudança de parâmetros verificada colocou limites para o município realizar uma gestão adequada do solo urbano e, portanto, de fazer cumprir a função social da propriedade, considerando a necessidade de adequação entre a intensificação do uso e ocupação do solo e a infraestrutura instalada
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The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.
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Since the beginning of the National Program for Production and Use of Biodiesel in Brazil, in 2004, different raw materials were evaluated for biodiesel production, trying to combine the agricultural diversity of the country to the desire to reduce production coasts. To determine the chemical composition of biodiesel produced from common vegetables oils, international methods have been used widely in Brazil. However, for analyzing biodiesel samples produced from some alternative raw materials analytical problems have been detected. That was the case of biodiesel from castor oil. Due the need to overcome these problems, new methodologies were developed using different chromatographic columns, standards and quantitative methods. The priority was simplifying the equipment configuration, realizing faster analyses, reducing the costs and facilitating the routine of biodiesel research and production laboratories. For quantifying free glycerin, the ethylene glycol was used in instead of 1,2,4-butanetriol, without loss of quality results. The ethylene glycol is a cheaper and easier standard. For methanol analyses the headspace was not used and the cost of the equipment used was lower. A detailed determination of the esters helped the deeper knowledge of the biodiesel composition. The report of the experiments and conclusions of the research that resulted in the development of alternative methods for quality control of the composition of the biodiesel produced in Brazil, a country with considerable variability of species in agriculture, are the goals of this thesis and are reported in the following pages
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Introducción: La relación entre el sueño y la calidad de vida constituye una de las problemáticas de gran importancia en el ámbito de las condiciones de trabajo de funcionarios y personal médico de las unidades prestadoras de servicios hospitalarios. Estudios han evidenciado una relación entre la calidad del sueño y la calidad de vida y la falta de sueño se ha asociado con errores en los procedimientos y lesiones ocupacionales. Objetivo: Relacionar la calidad del sueño con la calidad de vida en personal de salud de una Institución de IV nivel, en la ciudad de Caracas (Venezuela). Materiales y métodos: Estudio de corte transversal con datos secundarios del personal de salud de un Hospital de IV nivel (93 registros) en la ciudad de Caracas (Venezuela). Se emplearon variables sociodemográficas, las relacionadas con calidad del sueño y provenientes de la encuesta “Índice de calidad de sueño de Pittsburgh” y con calidad de vida incluidas en el cuestionario SF-36. Se utilizo el programa estadístico SPSS para el análisis y se obtuvieron medidas de tendencia central y dispersión. Para relacionar las variables se emplearon las pruebas de Shapiro Wilk y el coeficiente de correlación de Spearman. Resultados: El total de los trabadores que ingresaron al estudio tuvieron un rango de edad entre 19 y 70 años y una desviación estándar de 10,9 años. Respecto al género, el 79,6% (n=74) fueron mujeres, y el 20,4% (n=19) fueron hombres. Con relación al componente de calidad de vida, se encontró que la mayor puntuación se asocia con el desempeño emocional (61,3%), la Vitalidad (73,5%), la Función Física (91%), el Dolor Físico (100%) y la Función Social (100%). Igualmente, se encontró que la totalidad de los trabajadores encuestados refirieron ser malos dormidores (91.4%). Al correlacionar la calidad de sueño con la calidad de vida, se encontró una asociación estadísticamente significativa, específicamente con el componente Latencia de sueño (p=0.008), Eficiencia habitual de sueño (p=0,001), Perturbaciones del Sueño (p=0,040) y Disfunción diurna (p= 0,008). Conclusión Este estudio reporto que la falta de sueño tiene relación con la calidad de vida del personal de salud y que la totalidad de los trabajadores de este estudio refirieron ser malos dormidores, hechos que demandan la atención de los programas de salud de las empresas, para promover medidas preventivas y correctivas respecto a las condiciones laborales como parte del bienestar de las personas.
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O objetivo deste trabalho foi determinar a evapotranspiração e os coeficientes de cultura para a melancia (Citrullus lanatus L.), híbrido Olímpia, irrigada por gotejamento, cultivada em solo sob palhada de milheto e preparo convencional, nas condições edafoclimáticas da microrregião de Teresina, Piauí.
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Un hecho que pasa desapercibido para la mayoría de las personas, pero no para aquellas que viven cerca de las riberas de los ríos pequeños y quebradas, o para los ingenieros hidrológicos, es el aumento en la frecuencia y magnitud de las avenidas, especialmente cuando la cuenca de la corriente empieza a sufrir las consecuencias de la deforestación, para dar campo a la urbanización y expansión de la ciudad.Este aumento en la frecuencia de las avenidas por causa de un desequilibrio ecológico natural o artificial, que a su vez es provocado cuando se elimina parcial o totalmente la cobertura vegetal en la cuenca, es investigado en este trabajo, en un caso, a partir de fórmulas matemática empíricas deducidas de pruebas experimentales y en otro caso, utilizando una expresión matemática definida cuya representación gráfica se asemeje al hidrograma de una avenida, tal y como un sinusoide. De los resultados obtenidos en este trabajo, se infiere que cuando se dé una ecuación que represente la frecuencia probable de las avenidas en una corriente, debería indicarse que tal ecuación es válida para las condiciones que se observan en la cuenca al momento que se ha hecho el análisis, puesto que sin dicha cuenca se experimentará un gran cambio en su cobertura vegetal, la frecuencia de las avenidas variaría de manera muy significante, aumentando si hay deforestación o disminuyendo si se tiene un proceso de reforestación.
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Approximately 7.2% of the Atlantic rainforest remains in Brazil, with only 16% of this forest remaining in the State of Rio de Janeiro, all of it distributed in fragments. This forest fragmentation can produce biotic and abiotic differences between edges and the fragment interior. In this study, we compared the structure and richness of tree communities in three habitats - an anthropogenic edge (AE), a natural edge (NE) and the fragment interior (FI) - of a fragment of Atlantic forest in the State of Rio de Janeiro, Brazil (22°50'S and 42°28'W). One thousand and seventy-six trees with a diameter at breast height > 4.8 cm, belonging to 132 morphospecies and 39 families, were sampled in a total study area of 0.75 ha. NE had the greatest basal area and the trees in this habitat had the greatest diameter:height allometric coefficient, whereas AE had a lower richness and greater variation in the height of the first tree branch. Tree density, diameter, height and the proportion of standing dead trees did not differ among the habitats. There was marked heterogeneity among replicates within each habitat. These results indicate that the forest interior and the fragment edges (natural or anthropogenic) do not differ markedly considering the studied parameters. Other factors, such as the age from the edge, type of matrix and proximity of gaps, may play a more important role in plant community structure than the proximity from edges.
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The objectives of this work was to estimate the number of soil subsamples considering the classical statistics and geostatistics and determine the spatial variability of soil fertility attributes of an Ultisol, with clay texture, in an area of regenerating natural vegetation in Alegre - ES. Soil samples were collected in a depth of 0.0-0.2 m, at the crossing points of a regular grid, comprising a total of 64 points located at 10 m-intervals. The area presented low fertility soil. Considering a variation of 5% around the mean in the classic statistics, it is necessary a larger number of samples in relation to geostatistics. All the chemical attributes showed moderate to high spatial dependence, except for the effective cation exchange capacity (CECe), which showed pure nugget effect. The spherical semivariogram model gave the best fit to the data. Isoline maps allowed visualizing the differentiated spatial distribution of the contents of soil chemical attributes.
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This work approaches the forced air cooling of strawberry by numerical simulation. The mathematical model that was used describes the process of heat transfer, based on the Fourier's law, in spherical coordinates and simplified to describe the one-dimensional process. For the resolution of the equation expressed for the mathematical model, an algorithm was developed based on the explicit scheme of the numerical method of the finite differences and implemented in the scientific computation program MATLAB 6.1. The validation of the mathematical model was made by the comparison between theoretical and experimental data, where strawberries had been cooled with forced air. The results showed to be possible the determination of the convective heat transfer coefficient by fitting the numerical and experimental data. The methodology of the numerical simulations was showed like a promising tool in the support of the decision to use or to develop equipment in the area of cooling process with forced air of spherical fruits.
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In this work the performance of a sugar cane chopped harvester was analysed when fed with two sugar cane mass flows, measuring the invisible losses, which are impossible to measure in the field, harvester sugar cane cleaning efficiency and air velocity on extractors exit. The trial was done under controlled conditions at Copersucar Technology Center in January 2000. The results showed that the flow of sugar cane through the harvester doesn't influence the magnitudes of total invisible losses and raw material cleaning efficiency. The mean air velocity on the primary extractors exit was 12.0 m s-1, and 9.2 m s-1 on the secondary extractor, with a coefficient of variation of 21%, indicating that the poor cleaning performance of the harvester could be related to air velocity difference inside the extractor. Analyzing the data collected in the trials, it was possible to conclude that invisible losses in sugar cane harvester were 10% and the cleaning efficiency was 87%.
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No Tillage system is fully incorporated to farming in the region of Campos Gerais, state of Paraná. Accuracy and precision in the planting process are items of great importance for the success of this system. In order to evaluate the planting process, thirty eight farms were selected as sites for analysis of the placement depth of seeds. The research area was 4 or 5 planting rows, evaluating 10 plantlets per row. The average seed depth was around 46 mm, and significant differences between rows were observed in 21 areas. The average coefficient of variation was around 20%, the statistical limit between medium and high. Analyses of other parameters show that those coefficients may represent different errors in the process. The planting process in Campos Gerais can be considered efficient regarding to the average seed depth. However, the analysis of variability implies de need of actions concerning to anthropic and machinery factors.
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As a way to reduce water losses in furrow irrigation systems, used in fresh market tomato production, farmers are improperly distributing water into the field using plastic hose. The objective of this work was to study the suitability of using quick coupler sprinkler as hose connectors for water distribution in tomato plantation. The first step of the study was to assess the current hose field operation for tomato growers. Subsequently, four models of quick couplers sprinklers available in the market were tested in laboratory to determine the coefficient of resistance, the equivalent tube length, the head loss curve and the linking efficiency. As result, a structural design for hose connectors was presented using the model of coupling with the best hydraulic performance. Additionally, some technical recommendations on its use in irrigation water distribution are highlighted. Despite the requirement for additional field trials, the proposed system has potential to optimize the water use efficiency, to improve workers ergonomic conditions, and ensure good profitability to the producer.
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Size distributions in woody plant populations have been used to assess their regeneration status, assuming that size structures with reverse-J shapes represent stable populations. We present an empirical approach of this issue using five woody species from the Cerrado. Considering count data for all plants of these five species over a 12-year period, we analyzed size distribution by: a) plotting frequency distributions and their adjustment to the negative exponential curve and b) calculating the Gini coefficient. To look for a relationship between size structure and future trends, we considered the size structures from the first census year. We analyzed changes in number over time and performed a simple population viability analysis, which gives the mean population growth rate, its variance and the probability of extinction in a given time period. Frequency distributions and the Gini coefficient were not able to predict future trends in population numbers. We recommend that managers should not use measures of size structure as a basis for management decisions without applying more appropriate demographic studies.