Análise bioclimática e investigação do conforto térmico em ambientes externos: uma experiência no bairro de Petrópolis em Natal/RN

This study was intended to investigate how the urban form has been influencing the changes in the climate of the city and make a correlation between the climate and the thermal sensation of the users of open spaces. The research was developed in the district of Petrópolis in Natal/ RN whose occupation has been almost consolidated. Among other reasons, this district was selected because it was planned considering the environmental aspects of comfort. The methodologies used are based on KATZSCHNER (1997) and OLIVEIRA (1988) studies, which suggest the drawing and analysis of maps of the area under study, including topography, height of the buildings, land use, green areas, and types of soil pavement, as well as measurement of the environmental variables: air temperature, relative humidity, direction and wind speed for a comparative study. As part of this, study local users of the district were interviewed about their thermal sensations in open spaces. For the statistical analysis, data was collected at 10 distinct points characterized by BUSTOS ROMERO (2002), being 8 within the district and 2 at different places (outside the district), at climatologic stations, in 3 periods (August/2000, January/2002 and June/2002), for 4 consecutive days for each measurement (from Sunday to Wednesday) at the time of lower and higher temperatures in the city, 6:00 am and 1:00 pm, respectively. At the same time interviews were carried out with users of the open spaces in the area, totaling 171 valid formularies. The urban form showed a rather leveled topography, great diversity of land use and height of the buildings, with the existence of an area mostly occupied with high buildings, very little green area and soil practically impermeable. The statistical analysis showed high temperature and humidity levels. The wind direction is predominantly Southeast with extremely variable speeds. When the data from this district is compared with the data from other areas in the city and its outskirt, it was observed that this district is hotter and less ventilated than the others; besides, most users said that they felt uncomfortable in the local environmental conditions. The results of the analysis generated a zoning for the district with recommendations for soil occupation. The profile of the user was defined regarding the thermal comfort, as well as some discussion about the comfort parameters, including the proposal of limiting areas of temperature and humidity for the thermal comfort in the open spaces

Efeito da velocidade de aquecimento nas propriedades de produtos da cerâmica estrutural

Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 °C/min, 10 °C/min and 20 °C/min, with final temperatures of 850 °C, 950 °C and 1050 °C. Discontinuous cycles with rates of 10 °C/min or 15 °C/min up to 600 °C and a rate of 20 °C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 °C and fast fire sinterization up to 950 °C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries

Simulação de fluxo de fluidos em meios porosos desordenados uma análise de efeito de escala na estimativa da permeabilidade e do coeficiente de arrasto

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.

Metodologia para avaliação de cinemática de partículas gasosas em fluidos de viscosidade variável com o tempo e sua aplicação na construção de poços de petróleo

Many challenges have been presented in petroleum industry. One of them is the preventing of fluids influx during drilling and cementing. Gas migration can occur as result of pressure imbalance inside the well when well pressure becomes lower than gas zone pressure and in cementing operation this occurs during cement slurry transition period (solid to fluid). In this work it was developed a methodology to evaluate gas migration during drilling and cementing operations. It was considered gel strength concept and through experimental tests determined gas migration initial time. A mechanistic model was developed to obtain equation that evaluates bubble displacement through the fluid while it gels. Being a time-dependant behavior, dynamic rheological measurements were made to evaluate viscosity along the time. For drilling fluids analyzed it was verified that it is desirable fast and non-progressive gelation in order to reduce gas migration without affect operational window (difference between pore and fracture pressure). For cement slurries analyzed, the most appropriate is that remains fluid for more time below critical gel strength, maintaining hydrostatic pressure above gas zone pressure, and after that gels quickly, reducing gas migration. The model developed simulates previously operational conditions and allow changes in operational and fluids design to obtain a safer condition for well construction

Influência na qualidade final de metais retificados através da variação da velocidade de mergulho

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

Influência da hereditariedade nas capacidades motoras, na aptidão física e antropometria

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Variabilidade espacial de atributos químicos de um argissolo para aplicação de insumos à taxa variável em diferentes formas de relevo

A agricultura de precisão implica análise da variabilidade espacial de fatores de produção e a aplicação de insumos de forma localizada. Várias são as causas que condicionam a variabilidade espacial dos solos, sendo o relevo um dos fatores mais importantes. O presente estudo teve por objetivo analisar a variabilidade espacial dos atributos químicos do solo e a elaboração de mapas de necessidade de aplicação de insumos de forma localizada, em áreas com diferentes formas de relevo. Duas parcelas de 1 ha cada foram delimitadas em áreas com topografia côncava e convexa. Foram retiradas, em cada área, 242 amostras de solos em 121 pontos, nas profundidades de solo de 0,00-0,20 m e 0,20-0,40 m. Os resultados de análise química foram submetidos às análises da estatística descritiva, geoestatística e interpolação por krigagem. A área convexa apresentou maior variabilidade espacial do solo em relação a área côncava. A adoção da agricultura de precisão possibilitou economia de aproximadamente 25 kg ha-1 de P2O5 na área côncava.

Produtividade de híbridos de milho em função da velocidade de semeadura

O presente trabalho foi conduzido na área experimental do Laboratório de Máquinas e Mecanização Agrícola da UNESP - Jaboticabal, em um Latossolo Vermelho eutroférrico, em preparo convencional. Avaliaram-se o desenvolvimento e os componentes de produção de dois híbridos de milho (DKB 390, simples e DKB 435, duplo) em função de três velocidades do conjunto trator-semeadora-adubadora (5,4; 6,8 e 9,8 km h-1), totalizando seis tratamentos, com quatro repetições, em delineamento em blocos ao acaso, em esquema fatorial 2 x 3. Os resultados evidenciaram que o aumento da velocidade do conjunto trator-semeadora-adubadora reduziu a produtividade de grãos para o híbrido simples e não interferiu na produtividade do híbrido duplo. Apenas na menor velocidade (5,4 km h-1), o híbrido simples apresentou maior produtividade de grãos, comparado com o híbrido duplo. O aumento da velocidade na operação de semeadura reduziu a percentagem de espaçamentos normais entre as sementes, independentemente do híbrido estudado.

Semeadora-adubadora: exigências em função do preparo do solo, da pressão de inflação do pneu e da velocidade

As semeadoras-adubadoras, responsáveis pela correta adição de semente e adubo ao solo, possuem mecanismos dosadores acionados por suas rodas motrizes, que giram em função do contato com a superfície do solo. Esse contato é influenciado, entre outros fatores, pela pressão de inflação dos pneus. O objetivo do presente trabalho foi estudar o desempenho de uma semeadora-adubadora de precisão em função do preparo do solo (preparo convencional e plantio direto), das velocidades de deslocamento e da pressão de inflação do seu pneu. O trabalho foi realizado na UNESP de Jaboticabal (SP) no ano de 2006. Foram avaliadas as seguintes variáveis: força de tração e potência na barra, consumo de combustível (horário, ponderal, operacional e específico), capacidade de campo operacional, patinagem dos rodados do trator e da semeadora-adubadora, estande inicial e distribuição longitudinal de sementes. O sistema plantio direto demandou maior força (35 %), potência e consumo horário de combustível; o mesmo aconteceu na maior velocidade. A pressão de inflação das rodas da semeadora proporcionou menor patinagem e maior estande inicial de plântulas.

Demanda energética e eficiência da distribuição de sementes de milho sob variação de velocidade e condição de solo

O trabalho teve o objetivo de avaliar a demanda energética e a eficiência da distribuição de sementes de uma semeadora-adubadora para semeadura direta, submetida à variação de velocidade e condições de solo, na semeadura da cultura do milho. O estudo foi desenvolvido em um Nitossolo Vermelho distrófico, na Fazenda Experimental Lageado, no município de Botucatu - SP. O delineamento experimental foi em blocos casualizados, com oito repetições, combinando-se três velocidades de deslocamento (4,4; 6,1 e 8,1 km h-1) e duas condições de solo (solo manejado sob sistema de plantio direto há cinco anos e solo preparado com escarificador há 18 meses). Avaliaram-se a força de tração, a potência na barra de tração, o consumo de combustível, a capacidade de campo efetiva, a distribuição longitudinal de plantas, o coeficiente de variação, o índice de precisão e o número de plantas por hectare (estande inicial). Os resultados revelaram que, aumentando-se a velocidade de 4,4 para 8,1 km h-1, consegue-se aumentar em 86% a capacidade operacional, com incremento de 96% na demanda de potência na barra de tração e redução de 26% no consumo operacional de combustível. A maior velocidade (8,1 km h-1) proporcionou menor porcentual de espaçamentos normais e aumento no porcentual de espaçamentos múltiplos e falhos, maior coeficiente de variação e pior índice de precisão. A variação da velocidade não interferiu no número de plantas por hectare.

Desempenho de uma semeadora-adubadora direta, em função da velocidade de eslocamento e do tipo de manejo da biomassa da cultura de cobertura do solo

O objetivo do presente trabalho foi estudar o desempenho de uma semeadora-adubadora, operando em duas velocidades sobre a palhada da cultura do milheto (Pennisetum glaucum (L.) R. Brown), após diferentes manejos, na semeadura direta da cultura da soja (Glycine Max L.). O experimento foi realizado com seis tratamentos, em esquema fatorial, delineados em blocos ao acaso, com quatro repetições. Os tratamentos combinaram três manejos (triturador de palhas tratorizado, rolo- faca e herbicida) com duas velocidades de deslocamento da semeadora-adubadora (5,2 e 7,3 km h-1). Foram analisadas as seguintes variáveis: acúmulo e decomposição de massa seca do milheto, índice de emergência da cultura da soja, uniformidade de distribuição longitudinal de sementes, capacidade de campo efetiva da semeadora-adubadora e produtividade da soja. Os resultados mostraram que não houve diferença na decomposição da massa de milheto após os manejos e que esses, juntamente com a velocidade de deslocamento do conjunto trator-semeadora-adubadora, não influenciaram no número de dias para a emergência das plântulas de soja e na distribuição longitudinal das sementes. A capacidade de campo efetiva da semeadora-adubadora foi maior na velocidade mais alta. O rendimento de grãos não diferiu significativamente nos tratamentos estudados.

Análise dos indicadores de qualidade versus taxa de abandono utilizando método de regressão múltipla para serviço de banda larga

Telecommunication is one of the most dynamic and strategic areas in the world. Many technological innovations has modified the way information is exchanged. Information and knowledge are now shared in networks. Broadband Internet is the new way of sharing contents and information. This dissertation deals with performance indicators related to maintenance services of telecommunications networks and uses models of multivariate regression to estimate churn, which is the loss of customers to other companies. In a competitive environment, telecommunications companies have devised strategies to minimize the loss of customers. Loosing customers presents a higher cost than obtaining new ones. Corporations have plenty of data stored in a diversity of databases. Usually the data are not explored properly. This work uses the Knowledge Discovery in Databases (KDD) to establish rules and new models to explain how churn, as a dependent variable, are related to a diversity of service indicators, such as time to deploy the service (in hours), time to repair (in hours), and so on. Extraction of meaningful knowledge is, in many cases, a challenge. Models were tested and statistically analyzed. The work also shows results that allows the analysis and identification of which quality services indicators influence the churn. Actions are also proposed to solve, at least in part, this problem

Estabilidade e robustez de um controlador adaptativo indireto por um modelo de referência e estrutura variável

In this thesis, it is developed the robustness and stability analysis of a variable structure model reference adaptive controller considering the presence of disturbances and unmodeled dynamics. The controller is applied to uncertain, monovariable, linear time-invariant plants with relative degree one, and its development is based on the indirect adaptive control. In the direct approach, well known in the literature, the switching laws are designed for the controller parameters. In the indirect one, they are designed for the plant parameters and, thus, the selection of the relays upper bounds becomes more intuitive, whereas they are related to physical parameters, which present uncertainties that can be known easier, such as resistances, capacitances, inertia moments and friction coefficients. Two versions for the controller algorithm with the stability analysis are presented. The global asymptotic stability with respect to a compact set is guaranteed for both cases. Simulation results under adverse operation conditions in order to verify the theoretical results and to show the performance and robustness of the proposed controller are showed. Moreover, for practical purposes, some simplifications on the original algorithm are developed

Controle vetorial de velocidade de uma máquina de indução sem mancais trifásica com bobinado dividido utilizando estimação neural de fluxo

This work describes the study and the implementation of the vector speed control for a three-phase Bearingless induction machine with divided winding of 4 poles and 1,1 kW using the neural rotor flux estimation. The vector speed control operates together with the radial positioning controllers and with the winding currents controllers of the stator phases. For the radial positioning, the forces controlled by the internal machine magnetic fields are used. For the radial forces optimization , a special rotor winding with independent circuits which allows a low rotational torque influence was used. The neural flux estimation applied to the vector speed controls has the objective of compensating the parameter dependences of the conventional estimators in relation to the parameter machine s variations due to the temperature increases or due to the rotor magnetic saturation. The implemented control system allows a direct comparison between the respective responses of the speed and radial positioning controllers to the machine oriented by the neural rotor flux estimator in relation to the conventional flux estimator. All the system control is executed by a program developed in the ANSI C language. The DSP resources used by the system are: the Analog/Digital channels converters, the PWM outputs and the parallel and RS-232 serial interfaces, which are responsible, respectively, by the DSP programming and the data capture through the supervisory system

Avaliação de robustez, desempenho e aplicação do controlador adaptativo por posicionamento de pólos e estrutura variável

In this work, the variable structure adaptive pole placement controller (VS-APPC) robustness and performance are evaluated and this algorithm is applied in a motor control system. The controller robustness evaluation will be done through simulations, where will be introduced in the system the following adversities: time delay, actuator response boundeds, disturbances, parametric variation and unmodeled dynamics. The VS-APPC will be compared with PI control, pole placement control (PPC) and adaptive pole placement controller (APPC). The VS-APPC will be simulated to track a step and a sine reference. It will be applied in a three-phase induction motor control system to track a sine signal in the stator reference frame. Simulation and experimental results will prove the efficiency and robustness of this control strategy