17 resultados para Técnica de Amostragem Linear
em Universidade Federal do Rio Grande do Norte(UFRN)
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Universidade Estadual do Rio Grande do Norte
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The objective of the work was to investigate, from the vision of travel agents, the importance of environmental practices as a decision factor in the purchase of a tourist package. For in such a way, it was established as target population, the travel agencies and tourism linked to he Brazilian Association of Travel agencies ABAV, hearing the Brazilian travel agents that exerted the function in Natal, city in 2005. The election of the sample was accomplished using the simple random sampling technique. The amount of agents effectively searched was of 150 agents being distributed 150 questionnaires, with closed and opened questions, applied during the month of November in 2005. Results showed great variability of interviewed answers in that if it relates for sale of package tourist where the customer demonstrates enviromental concern with the environmental quality. Through multiple regression analyses, it was environmental concern with the environmental quality of the place and the perception of the practical importance of the existence environmental practices in the place as important factor in the decision of tourist package purchase
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In recent decades, changes have been occurring in the telecommunications industry, allied to competition driven by the policies of privatization and concessions, have fomented the world market irrefutably causing the emergence of a new reality. The reflections in Brazil have become evident due to the appearance of significant growth rates, getting in 2012 to provide a net operating income of 128 billion dollars, placing the country among the five major powers in the world in mobile communications. In this context, an issue of increasing importance to the financial health of companies is their ability to retain their customers, as well as turn them into loyal customers. The appearance of infidelity from customer operators has been generating monthly rates shutdowns about two to four percent per month accounting for business management one of its biggest challenges, since capturing a new customer has meant an expenditure greater than five times to retention. For this purpose, models have been developed by means of structural equation modeling to identify the relationships between the various determinants of customer loyalty in the context of services. The original contribution of this thesis is to develop a model for loyalty from the identification of relationships between determinants of satisfaction (latent variables) and the inclusion of attributes that determine the perceptions of service quality for the mobile communications industry, such as quality, satisfaction, value, trust, expectation and loyalty. It is a qualitative research which will be conducted with customers of operators through simple random sampling technique, using structured questionnaires. As a result, the proposed model and statistical evaluations should enable operators to conclude that customer loyalty is directly influenced by technical and operational quality of the services offered, as well as provide a satisfaction index for the mobile communication segment
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This work purposes the application of a methodology to optimize the implantation cost of an wind-solar hybrid system for oil pumping. The developed model is estimated the implantation cost of system through Multiple Linear Regression technique, on the basis of the previous knowledge of variables: necessary capacity of storage, total daily energy demand, wind power, module power and module number. These variables are gotten by means of sizing. The considered model not only can be applied to the oil pumping, but also for any other purposes of electric energy generation for conversion of solar, wind or solar-wind energy, that demand short powers. Parametric statistical T-student tests had been used to detect the significant difference in the average of total cost to being considered the diameter of the wind, F by Snedecor in the variance analysis to test if the coefficients of the considered model are significantly different of zero and test not-parametric statistical by Friedman, toverify if there is difference in the system cost, by being considered the photovoltaic module powers. In decision of hypothesis tests was considered a 5%-significant level. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 3 HP. The configurations module powers showed significant differences in total cost of investment by considering an electrical motor of 5 HP only to wind speed of 4m/s and 6 m/s in wind of 3 m, 4m and 5 m of diameter. There was not significant difference in costs to diameters of winds of 3 m and 4m. The mathematical model and the computational program may be used to others applications which require electrical between 2.250 W and 3.750 W. A computational program was developed to assist the study of several configurations that optimizes the implantation cost of an wind-solar system through considered mathematical model
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The Callitrichidae family is characterized by flexibility in its mating system, being possible to find monogamous, polyandrid and polygynic groups. Its social organization and mating system can be defined by the interaction between ecological and demographic factors plus the degree of relatedness among the individuals in the population. The objective of this work was to demonstrate the influence of relatedness and coexistence on the establishment and maintenance of social relations between Callithrix jacchus adult males. Four pairs of related adult males (CP), 4 pairs with coexistence between the animals in the pair (CC) and 4 pairs with no relatedness (SP) were studied. The pairs in the group CC had been kept in the same cage for at least 8 months before the experiment and the pairs in the group SP were put together at the beginning of the study. Each animal was observed 3 times/week for 2 months, in 15 min. sessions, through focal time sampling with instantaneous record each minute. In the first month, only the pair of males was kept in the cage (Phase I) and in the second month, a female was introduced into the cage (Phase II). The affiliative, agonistic and sexual interactions were registered. Affiliative interactions showed similar frequencies for all groups in phases. There was also no significant difference in the agonistic interactions of the CP, CC and SP males in Pase I, even considering that group SP exhibited higher levels of agonism. In Phase II, there was a statistically significant increase comparing to the others. The results demonstrate that relatedness and coexistence are of great importance for maintaining reprodutive and social stability inside the group. Nonetheless, in this study, only one of the males in the pair had sexual interations with the females, except for 2 pairs. This was assured through mate guarding and agonism directed to the potencial competitor. The most probable mating system would be functional monogamy, where the males would present low levels of competition, if there is relatedness and coexistence among them; on the other hand, a strong competition if there is no relatedness between the individuals. Even so, a polyandric system would also have to be considered
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Callithrix jacchus, as the other species in the family Callitrichidae, lives in social groups. The groups cam be found in different habitats, whose distinct floristic physiognomies and communities are intrinsically related to their behavioral ecology and social relations. Our objective was to describe the social relations and feeding behavior of Callithrix jacchus in the Bioma Caatinga. We observed a group at the FLONA (National Forest IBAMA), in Açu-RN, in northeastern Brazil, compose of five adults (2 females and 3 males) at the beginning of the study. The birth of five animals was registered along the study. The following behavioral categories were registered along eleven months, once a week, through instantaneous focal animal sampling: social grooming, contact, proximity, foraging, feeding, locomotion and rest. Foraging presented the highest levels comparing to other activities, and was more frequent in the dry season. Social grooming was the second more frequent activity, with higher levels in the rainy season, and between the reproductive couple. We found similar results for proximity. The most explored feeding item was the gum, specially in the rainy season. The most explored species for exudates feeding were Cirus limon (limão) and Pitecolobiun foliolosum (jurema branca). The comparision of fruit and insect ingestion between the seasons showed higher percentage for both in the dry season. The general activity pattern was similar to what is registeded in groups the inhabit the Atlantic Forest. These results indicate the flexibility of the species which survives and reproduces in such physically and biologically different environments
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Corrosion inhibitors in solution are utilized to minimize processes from corrosion in steel. Of the present dissertation was evaluated the efficiency by inhibition from the surfactant saponified coconut oil (OCS) in the carbon steel 1020 through in linear polarization electrochemistry technique, well as, studied the process from adsorption through from the isotherms from Langmuir, Frumkin and Temkin. The corrosion current was determined through in Tafel extrapolation from the curves in the polarization, and then, was calculated the efficiency in the inhibitor to each concentration and temperature. Were studied four concentrations (12,5 ppm, 25 ppm, 50 ppm, and 75 ppm) in the inhibitor OCS and one in the NaCl salt (10.000 ppm) in six temperatures (301 K, 308 K, 313 K, 318 K, 323 K, and 328 K) in triplicate. By the results obtained observed that the technique applied can evaluated with rapidity and efficiency corrosion inhibitors. In relation to the isotherms, the than best appropriated was the in Langmuir and in the concentrations studied, the that obtained the best efficiency was the concentration of 75 ppm
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The study consists in an analysis of researches with tourism issues, in Master s and Doctoral level, investigating their epistemological trends, regarding the type of study that is being produced and the methods used. It is characterized as exploratory, documental and bibliographical, having undertaken a cross-sectional study which covers the period from 2007 to 2011. It analyzes the context of academically production in tourism, the nature of these researches, the methodological aspects adopted in these theses and dissertations, the philosophical inclinations and the coherence and contribution of the same. This research uses, the Digital Library of Theses and Dissertations (BDTD) and the secretariats of the Academic Centers of the Federal University of Rio Grande do Norte (UFRN) as means to collect data. It employs the technique of sampling by judgment and undertakes the research in various Academic Centers in UFRN, using the method of content analysis. It shows that, from the 643 studies analyzed, 43 of them have themes related to tourism, which characterized this study sample. This study realizes that PPGA is the largest producer of researches on tourism issues, ahead of PPGTur, which ranks the third position, in this aspect. Also realizes that all surveys analyzed are crosssectional and the theme further investigated, with 21% of the sample, is related to the marketing aspects of tourism, with the theme Directors of Hotels and Restaurants (DHR) . This research demonstrates that all sample surveys make use of interviews, and these are, mostly, structured. Also realizes that most of these studies, with 21% of the sample, employ the method of content analysis. The references in Portuguese are surveyed about five times more than the ones in other languages. It estimates that more than half of the sample is characterized as positivist, associated with aspects of functionalism. A minority of 21% of these researches seeks to identify and recommend solutions to the tourism issues, or even represent part of them. This research concludes that the studies in tourism are mostly unifocal, being driven by issues related to the touristic trade. PPGTur produces a number still unrepresentative of studies. The theses and dissertations of the sample are limited and/or unable to analyze the changes of the phenomenon caused by the time. The studies from the sample present criteria and make use of other methods and techniques to associate with the interviews and content analysis to obtain more solid and reliable data and results. They use a low number of references in languages other than Portuguese. Most of these studies, characterized as positivist-functionalist, investigate the functioning, planning, coordination and expectations in organizations, leaving aside other issues, also relevant for tourism. The number of studies aimed at identifying solutions to the problems of tourism, or that even represents part of them, is not expressive
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A fragilidade brasileira quanto à competitividade turística é um fato observável nos dados da Organização Mundial do Turismo. O Brasil caiu em 2011, da 45ª para a 52ª posição, apesar de liderar no atributo recursos naturais e estar colocado na 23° em recursos culturais. Assim, grandes interesses e esforços têm sido direcionados para o estudo da competitividade dos produtos e destinos turísticos. O destino turístico é caracterizado por um conjunto complexo e articulado de fatores tangíveis e intangíveis, apresentando alta complexidade, dados de elevada dimensionalidade, não linearidade e comportamento dinâmico, tornando-se difícil a modelagem desses processos por meio de abordagens baseadas em técnicas estatísticas clássicas. Esta tese investigou modelos de equações estruturais e seus algoritmos, aplicados nesta área, analisando o ciclo completo de análise de dados, em um processo confirmatório no desenvolvimento e avaliação de um modelo holístico da satisfação do turista; na validação da estrutura do modelo de medida e do modelo estrutural, por meio de testes de invariância de múltiplos grupos; na análise comparativa dos métodos de estimação MLE, GLS e ULS para a modelagem da satisfação e na realização de segmentação de mercado no setor de destino turístico utilizando mapas auto-organizáveis de Kohonen e sua validação com modelagem de equações estruturais. Aplicações foram feitas em análises de dados no setor de turismo, principal indústria de serviços do Estado do Rio Grande do Norte, tendo sido, teoricamente desenvolvidos e testados empiricamente, modelos de equações estruturais em padrões comportamentais de destino turístico. Os resultados do estudo empírico se basearam em pesquisas com a técnica de amostragem aleatória sistemática, efetuadas em Natal-RN, entre Janeiro e Março de 2013 e forneceram evidências sustentáveis de que o modelo teórico proposto é satisfatório, com elevada capacidade explicativa e preditiva, sendo a satisfação o antecedente mais importante da lealdade no destino. Além disso, a satisfação é mediadora entre a geração da motivação da viagem e a lealdade do destino e que os turistas buscam primeiro à satisfação com a qualidade dos serviços de turismo e, posteriormente, com os aspectos que influenciam a lealdade. Contribuições acadêmicas e gerenciais são mostradas e sugestões de estudo são dadas para trabalhos futuros.
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Comparar o desenvolvimento de profissionais e estudantes de enfermagem quanto à realização da técnica de curativo. Metodologia: estudo descritivo com abordagem quantitativa. A amostra foi escolhida através de amostragem por conveniência, tendo participado da pesquisa 14 profissionais de enfermagem, que foram observados no período de março a junho de 2009, e 24 estudantes de enfermagem, regularmente matriculados no último período do Curso de Graduação em Enfermagem da Universidade Federal da Paraíba, os quais foram observados no período de março e maio de 2010. O procedimento de coleta de dados foi efetuado através da observação não participante e preenchimento de um roteiro semi-estruturado, após a aprovação do Comitê de Ética em Pesquisa do Hospital Universitário Lauro Wanderley, sob Protocolo n. 011/09. Resultados: na maioria dos aspectos analisados, os estudantes se sobressaíram aos profissionais, principalmente com relação à lavagem das mãos, orientação do paciente e utilização de movimentos únicos para limpeza da ferida. Conclusão: os profissionais devem melhorar seu conhecimento, buscando atualização nessa área, e os estudantes devem ser supervisionados durante a realização do procedimento
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This work deals with an on-line control strategy based on Robust Model Predictive Control (RMPC) technique applied in a real coupled tanks system. This process consists of two coupled tanks and a pump to feed the liquid to the system. The control objective (regulator problem) is to keep the tanks levels in the considered operation point even in the presence of disturbance. The RMPC is a technique that allows explicit incorporation of the plant uncertainty in the problem formulation. The goal is to design, at each time step, a state-feedback control law that minimizes a 'worst-case' infinite horizon objective function, subject to constraint in the control. The existence of a feedback control law satisfying the input constraints is reduced to a convex optimization over linear matrix inequalities (LMIs) problem. It is shown in this work that for the plant uncertainty described by the polytope, the feasible receding horizon state feedback control design is robustly stabilizing. The software implementation of the RMPC is made using Scilab, and its communication with Coupled Tanks Systems is done through the OLE for Process Control (OPC) industrial protocol
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This work presents a modelling and identification method for a wheeled mobile robot, including the actuator dynamics. Instead of the classic modelling approach, where the robot position coordinates (x,y) are utilized as state variables (resulting in a non linear model), the proposed discrete model is based on the travelled distance increment Delta_l. Thus, the resulting model is linear and time invariant and it can be identified through classical methods such as Recursive Least Mean Squares. This approach has a problem: Delta_l can not be directly measured. In this paper, this problem is solved using an estimate of Delta_l based on a second order polynomial approximation. Experimental data were colected and the proposed method was used to identify the model of a real robot
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Slugging is a well-known slugging phenomenon in multiphase flow, which may cause problems such as vibration in pipeline and high liquid level in the separator. It can be classified according to the place of its occurrence. The most severe, known as slugging in the riser, occurs in the vertical pipe which feeds the platform. Also known as severe slugging, it is capable of causing severe pressure fluctuations in the flow of the process, excessive vibration, flooding in separator tanks, limited production, nonscheduled stop of production, among other negative aspects that motivated the production of this work . A feasible solution to deal with this problem would be to design an effective method for the removal or reduction of the system, a controller. According to the literature, a conventional PID controller did not produce good results due to the high degree of nonlinearity of the process, fueling the development of advanced control techniques. Among these, the model predictive controller (MPC), where the control action results from the solution of an optimization problem, it is robust, can incorporate physical and /or security constraints. The objective of this work is to apply a non-conventional non-linear model predictive control technique to severe slugging, where the amount of liquid mass in the riser is controlled by the production valve and, indirectly, the oscillation of flow and pressure is suppressed, while looking for environmental and economic benefits. The proposed strategy is based on the use of the model linear approximations and repeatedly solving of a quadratic optimization problem, providing solutions that improve at each iteration. In the event where the convergence of this algorithm is satisfied, the predicted values of the process variables are the same as to those obtained by the original nonlinear model, ensuring that the constraints are satisfied for them along the prediction horizon. A mathematical model recently published in the literature, capable of representing characteristics of severe slugging in a real oil well, is used both for simulation and for the project of the proposed controller, whose performance is compared to a linear MPC
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In recent decades, ceramic products have become indispensable to the technological development of humanity, occupying important positions in scientific production and consequently in industrial production. One area of the economy that continues to absorb large amounts of the products of this sector is Construction. Among the branches of the ceramic industry, there are the red ceramic industry which is traditionally the basis of that economic sector. Among the reasons for which the red ceramic industry became popular in the country, and specifically in Rio Grande do Norte, is the abundance of this raw material, easily found throughout the national territory. However, it appears that the red ceramic industry has deficiencies in technology and skilled labor, resulting in the production of ceramic goods with low added value. Among the factors that determine the quality of the ceramic products red has the proper formulation of the ceramic mass, the conformation and the firing temperature. Thus, the overall goal of this work is to study the mineralogical and technological properties, two clays from the region of the Wasteland Potiguar industrial ceramist. Therefore, the raw materials were characterized by analysis of Xray diffraction (XRD) analysis, X-ray fluorescence (XRF), particle size analysis (FA), scanning electron microscopy (SEM), optical microscopy (OM ), plasticity index (PI), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA). The technological properties of the material were analyzed by water absorption tests (AA%) porosity (% PA), the linear shrinkage (RT%), apparent density (MEA), loss on ignition (PF%) and flexural strength three points (TRF)
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This dissertation aims the development of an experimental device to determine quantitatively the content of benzene, toluene and xylenes (BTX) in the atmosphere. BTX are extremely volatile solvents, and therefore play an important role in atmospheric chemistry, being precursors in the tropospheric ozone formation. In this work a BTX new standard gas was produced in nitrogen for stagnant systems. The aim of this dissertation is to develop a new method, simple and cheaper, to quantify and monitor BTX in air using solid phase microextraction/ gas chromatography/mass spectrometry (SPME/CG/MS). The features of the calibration method proposed are presented in this dissertation. SPME sampling was carried out under non-equilibrium conditions using a Carboxen/PDMS fiber exposed for 10 min standard gas mixtures. It is observed that the main parameters that affect the extraction process are sampling time and concentration. The results of the BTX multicomponent system studied have shown a linear and a nonlinear range. In the non-linear range, it is remarkable the effect of competition by selective adsorption with the following affinity order p-xylene > toluene > benzene. This behavior represents a limitation of the method, however being in accordance with the literature. Furthermore, this behavior does not prevent the application of the technique out of the non-linear region to quantify the BTX contents in the atmosphere.