891 resultados para Bayesian risk prediction models


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Bidens pilosa é uma das mais importantes plantas daninhas que ocorrem em lavouras anuais e perenes da região Centro-Sul do Brasil. A grande capacidade de produção de aquênios é uma das suas principais estratégias de sobrevivência, e o conhecimento das condições fundamentais para germinação e emergência das plântulas é essencial para predição do crescimento populacional e para a elaboração de plano de manejo de suas infestações e de seus biótipos resistentes aos herbicidas. Foram conduzidos ensaios em condições de casa de vegetação, onde foi avaliada a emergência de aquênios de B. pilosa em diferentes profundidades (0, 1, 2, 3, 4 e 5 cm). Os experimentos foram conduzidos nos meses de maio, agosto e novembro de 2006 e em março de 2007. Os resultados mostraram que a emergência de plântulas de picão-preto foi bastante afetada pela localização do aquênio no perfil do solo, ocorrendo expressiva redução a partir de 2 cm de profundidade. Essa característica da biologia reprodutiva do picão-preto é importante para a formação de densos bancos de sementes em solos submetidos ao preparo convencional, onde grande parte da chuva de sementes é nele incorporada.

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In this dissertation new models of propagation path loss predictions are proposed by from techniques of optimization recent and measures of power levels for the urban and suburban areas of Natal, city of Brazilian northeast. These new proposed models are: (i) a statistical model that was implemented based in the addition of second-order statistics for the power and the altimetry of the relief in model of linear losses; (ii) a artificial neural networks model used the training of the algorithm backpropagation, in order to get the equation of propagation losses; (iii) a model based on the technique of the random walker, that considers the random of the absorption and the chaos of the environment and than its unknown parameters for the equation of propagation losses are determined through of a neural network. The digitalization of the relief for the urban and suburban areas of Natal were carried through of the development of specific computational programs and had been used available maps in the Statistics and Geography Brazilian Institute. The validations of the proposed propagation models had been carried through comparisons with measures and propagation classic models, and numerical good agreements were observed. These new considered models could be applied to any urban and suburban scenes with characteristic similar architectural to the city of Natal

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The telecommunications industry has experienced recent changes, due to increasing quest for access to digital services for data, video and multimedia, especially using the mobile phone networks. Recently in Brazil, mobile operators are upgrading their networks to third generations systems (3G) providing to users broadband services such as video conferencing, Internet, digital TV and more. These new networks that provides mobility and high data rates has allowed the development of new market concepts. Currently the market is focused on the expansion of WiMAX technology, which is gaining increasingly the market for mobile voice and data. In Brazil, the commercial interest for this technology appears to the first award of licenses in the 3.5 GHz band. In February 2003 ANATEL held the 003/2002/SPV-ANATEL bidding, where it offered blocks of frequencies in the range of 3.5 GHz. The enterprises who purchased blocks of frequency were: Embratel, Brazil Telecom (Vant), Grupo Sinos, Neovia and WKVE, each one with operations spread in some regions of Brazil. For this and other wireless communications systems are implemented effectively, many efforts have been invested in attempts to developing simulation methods for coverage prediction that is close to reality as much as possible so that they may become believers and indispensable tools to design wireless communications systems. In this work wasm developed a genetic algorithm (GA's) that is able to optimize the models for predicting propagation loss at applicable frequency range of 3.5 GHz, thus enabling an estimate of the signal closer to reality to avoid significant errors in planning and implementation a system of wireless communication

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The development of wireless telecommunication in the last years has been great. It has been taking academics to conceive new ideas and techniques. Their aims are to increase the capacity and the quality of the system s services. Cells that are smaller every time, frequencies that are every time higher and environments that get more and more complex, all those facts deserve more accurate models the propagation prediction techniques are inserted in this context and results with a merger of error that is compatible with the next generations of communication systems. The objective of this Work is to present results of a propagation measurement campaign, aiming at pointing the characteristics of the mobile systems covering in the city of Natal (state of Rio Grande do Norte, Brazil). A mobile laboratory was set up, using the infra-structure available and frequently used by ANATEL. The measures were taken in three different areas: one characterized by high buildings, high relief, presence of trees and towers of different highs. These areas covered the city s central zone, a suburban / rural zone and a section of coast surrounded by sand dunes. It is important to highlight that the analysis was made taking into consideration the actual reality of cellular systems with covering ranges by reduced cells, with the intent of causing greater re-use of frequencies and greater capacity of telephone traffic. The predominance of telephone traffic by cell in the city of Natal occurs within a range inferior to 3 (three) km from the Radio-Base Station. The frequency band used was 800 MHz, corresponding to the control channels of the respective sites, which adopt the FSK modulation technique. This Dissertation starts by presenting a general vision of the models used for predicting propagation. Then, there is a description of the methodology used in the measuring, which were done using the same channels of control of the cellular system. The results obtained were compared with many existing prediction models, and some adaptations were developed by using regression techniques trying to obtain the most optimized solutions. Furthermore, according to regulations from the old Brazilian Holding Telebrás, a minimum covering of 90% of a determined previously area, in 90% of the time, must be obeyed when implanting cellular systems. For such value to be reached, considerations and studies involving the specific environment that is being covered are important. The objective of this work is contribute to this aspect

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In this work calibration models were constructed to determine the content of total lipids and moisture in powdered milk samples. For this, used the near-infrared spectroscopy by diffuse reflectance, combined with multivariate calibration. Initially, the spectral data were submitted to correction of multiplicative light scattering (MSC) and Savitzsky-Golay smoothing. Then, the samples were divided into subgroups by application of hierarchical clustering analysis of the classes (HCA) and Ward Linkage criterion. Thus, it became possible to build regression models by partial least squares (PLS) that allowed the calibration and prediction of the content total lipid and moisture, based on the values obtained by the reference methods of Soxhlet and 105 ° C, respectively . Therefore, conclude that the NIR had a good performance for the quantification of samples of powdered milk, mainly by minimizing the analysis time, not destruction of the samples and not waste. Prediction models for determination of total lipids correlated (R) of 0.9955, RMSEP of 0.8952, therefore the average error between the Soxhlet and NIR was ± 0.70%, while the model prediction to content moisture correlated (R) of 0.9184, RMSEP, 0.3778 and error of ± 0.76%

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Software Repository Mining (MSR) is a research area that analyses software repositories in order to derive relevant information for the research and practice of software engineering. The main goal of repository mining is to extract static information from repositories (e.g. code repository or change requisition system) into valuable information providing a way to support the decision making of software projects. On the other hand, another research area called Process Mining (PM) aims to find the characteristics of the underlying process of business organizations, supporting the process improvement and documentation. Recent works have been doing several analyses through MSR and PM techniques: (i) to investigate the evolution of software projects; (ii) to understand the real underlying process of a project; and (iii) create defect prediction models. However, few research works have been focusing on analyzing the contributions of software developers by means of MSR and PM techniques. In this context, this dissertation proposes the development of two empirical studies of assessment of the contribution of software developers to an open-source and a commercial project using those techniques. The contributions of developers are assessed through three different perspectives: (i) buggy commits; (ii) the size of commits; and (iii) the most important bugs. For the opensource project 12.827 commits and 8.410 bugs have been analyzed while 4.663 commits and 1.898 bugs have been analyzed for the commercial project. Our results indicate that, for the open source project, the developers classified as core developers have contributed with more buggy commits (although they have contributed with the majority of commits), more code to the project (commit size) and more important bugs solved while the results could not indicate differences with statistical significance between developer groups for the commercial project

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

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Three trials were carried out to determine energy metabolized (EM) requirement model for starting and growing pullets from different strains, at five ambient temperatures and different percentage feather coverage. In Trial I, metabolizable energy requirements for maintenance (MEm) and efficiency of energy utilization were estimated using 64 birds of two different strains, Hy-Line W36 (HLW36) and Hy-Line Semi-heavy (HLSH), from 9 to 13 weeks of age. The effects of ambient temperature (12, 18, 24, 30 and 36ºC) and percentage feather coverage (0, 50 and 100%) on MEm were assessed in the second trial, using 48 birds per temperature per strain (HLSH and HLW36) from 9 to 13 weeks of age. Trial III evaluated ME requirements for weight gain (MEg) using 1,200 birds from two light strains (HLW36 and Hisex Light, HL) and two semi-heavy strains (HLSH and Hisex Semi-heavy, HSH) reared until 18 weeks of age. According to the prediction models, MEm changed as a function of temperature and feather coverage, whereas MEg changed as a function of age and bird strain. Thus, two models were developed for birds aged 1 to 6 weeks, one model for the light strain and one for the semi-heavy strain. Energy requirements (ER) were different among strains from 7 to 12 weeks, and therefore 4 models were elaborated. From 13 to 18 weeks, one single model was produced for semi-heavy birds, since ER between semi-heavy strains were not different, whereas two different models were elaborated for the light layers. MEg of light birds was higher than MEg of semi-heavy birds, independent of age.

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The objective of this study was to estimate genetic parameters for body weights at weaning (PD), 12 months old (P12) and adult age (PAD), culling age (TPR, days in herd), number (ND10) and kilograms (QD10) of calves weaned up to ten years of age, total number (NDT) and total kilograms (QDT) of calves weaned during herd life, and kilograms of calves weaned per year in herd (QTPR) of Canchim (5/8 Charolais + 3/8 Zebu) females from one herd. Data consisted of 3,249, 3.111, 1,138, 1,340, 1,362, 1,362, 1,340, 1,340 and 1,340 records of PD, P12, PAD, TPR, ND10, QD10, NDT, QDT and QTPR. respectively. Variance and covariance components were estimated by bivariate analyses between PD, P12 and PAD and other production traits using Bayesian inference. The models included the additive direct, permanent environmental and residual random effects and the fixed effects year and month of birth or calving, calving age and age of the animal, depending on the trait. QD10, QDT and QTPR of each female were obtained by adjusting the weaning weights of calves for year and month of birth, sex and age of cow. Average of heritability estimates were 0.38 (PD), 0.40 (P12), 0.54 (PAD), 0.22 (TPR), 0.22 (ND10), 0.24 (QD10), 0.23 (NDT), 0.23 (QDT) and 0.32 (QTPR), indicating genetic variability to obtain response by selection. Genetic correlations between TPR (-0.02, 0.26 and -0.12), ND10 (0.04, 0.10 and -0.29), QD10 (0.37, 0.39 and -0.13), NDT (-0.03, 0.14 and -0.25), QDT (0.20, 0.33 and -0.16), QTPR (0.21, 0.28 and -0.19) and body weights (PD, P12 and PAD) suggest that selection of females based on weaning and 12-month body weights will not affect productivity. However, it may be decreased by increasing female adult body weight.

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Twenty eight Mediterranean buffaloes bulls were scanned with real-time ultrasound (RTU), slaughtered, and fabricated into retail cuts to determine the potential for ultrasound measures to predict carcass retail yield. Ultrasound measures of fat thickness, ribeye area and rump fat thickness were recorded three to five days prior to slaughter. Carcass measurements were taken, and one side of each carcass was fabricated into retail cuts. Stepwise regression analysis was used to compare possible models for prediction of either kilograms or percent retail product from carcass mesaurements and ultrasound measures. Results indicate that possible prediction models for percent or kilograms of retail products using RTU measures were similar in their predictive power and accuracy when compared to models derived from carcass measurements. Both fat thickness and ribeye area were over-predicted when measured ultrasonically compared to measurements taken on the carcass in the cooler. The mean absolute differences for both traits are larger than the mean differences, indicating that some images were interpreted to be larger and some smaller than actual carcass measurements. Ultrasound measurements of REA and FT had positive correlations with carcass measures of the same traits (r=.96 for REA and r=.99 for FT). Standard errors of prediction currently are being used as the standard to certify ultrasound technicians for accuracy. Regression equations using live weight (LW), rib eye area (REAU) and subcutaneous fat thickness (FTU) between 12(th) and 13 (th) ribs and also over the biceps femoris muscle (FTP8) by ultrasound explained 95% of the variation in the hot carcass weight when measure immediately before slaughter.

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O projeto de sistemas de comunicações móveis requer o conhecimento do ambiente em que será implementado. Para tanto, busca-se a exatidão na predição de propagação do sinal através do uso de modelos de predição. O presente trabalho propõe um modelo empírico para a estimativa da intensidade de sinal recebida em ambientes indoor, e que apresentam mais de uma fonte transmissora, utilizando Sistema de Antenas Distribuídas (DAS). O método apresenta uma generalização para o caso de múltiplas fontes, também chamado multifontes, e como caso particular com apenas uma fonte. A modelagem é feita através do uso de radiais partindo de cada transmissor, com o intuito de considerar a variabilidade do sinal em ambientes indoor. Estas várias perturbações no sinal, que causam desvanecimento rápido são caracterizadas através das distribuições estatísticas de desvanecimento. As mais utilizadas como a de Rayleigh, Rice e Nakagami são apresentadas para caracterização do canal, além dessas são calculadas as distribuições recentemente desenvolvidas, de Kappa-mi e Eta-mi. Para a validação do modelo realizaram-se campanhas de medições em um shopping center, que possui um DAS, com o teste em dois ambientes distintos, um supermercado e uma praça de alimentação. As simulações são realizadas no software MATLAB® e o desempenho dos resultados avaliados através do cálculo dos erros absoluto, desvio padrão e erro rms.

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Este trabalho trata de alguns modelos de propagação de ondas eletromagnéticas. Primeiramente, foram analisados modelos relacionados com a predição do sinal eletromagnético em ambientes indoor. Os modelos utilizados neste trabalho foram o Traçado de Raios, Caminho Dominante de Energia (DPM) e o FDTD. Para os dois primeiros modelos foi, utilizado um software comercial e para o método FDTD foi desenvolvido um algoritmo para o qual o sinal é analisado em um ambiente com a mesma geometria utilizada no software. Os resultados, para os pontos de recepção analisados, fornecidos pelos três modelos, são concordantes. Verifica-se a influência dos fenômenos de propagação na intensidade do sinal. A relevância deste trabalho encontra-se no fato de não haver, na literatura pesquisada, trabalhos que comparassem os três modelos de predição mencionados, além de propor temas para pesquisas futuras.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)