Dissertations/Thesis

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2025
Dissertations
1
  • EMANUELA RODRIGUES DO NASCIMENTO
  • Statistical approach for the effect of maturity on the physicochemical properties of jackfruit (Artocarpus heterophyllus) of hard and soft varieties

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • MOACYR CUNHA FILHO
  • TATIJANA STOSIC
  • NEIDE KAZUE SAKUGAWA SHINOHARA
  • Data: Jan 16, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Jackfruit (Artocarpus heterophyllus) is a segmented fruit that grows directly from the trunk and thickest branches of the jackfruit tree and can weigh up to 10 kilos and measure 40 cm in length. The fruit can have more than 100 berries, and can be slightly hard or completely soft, hence the distinction between two varieties popularly known as soft jackfruit and hard jackfruit, respectively. Jackfruit can be consumed raw, in the form of vegetable meat, sweets and liqueur (extracted from its pulp). The seeds of both species are consumed cooked and roasted. Jackfruit is a yellow fruit, with shades that vary between light and dark, with very peculiar physical and chemical characteristics that are little reported by the scientific community. The size of the fruit is impressive and sets it apart from other cultivars, being the largest of all fruits produced on trees. This study aimed to statistically evaluate the quality of minimally processed jackfruits for the two varieties (soft and hard) in terms of physical and chemical composition. Six immature (green) fruits of each variety were used to characterize the pulp composition of each variety. The data obtained were subjected to the Shapiro-Wilk normality test and Bartlett homogeneity test. The non-parametric Kruskal-Wallis test and Dunn's post-test were applied for values that did not follow normality, and the ANOVA test and Tukey's post-test were applied for those that followed normality and homogeneity. To measure the distance between the peaks found in the fruit peel, the Euclidean distance and the K-mean method were used. The statistical software R was used to process the analyses. The results indicate that the green jackfruit fruit presents similar behavior in the physical-chemical analyses for the two varieties used. There was only a significant difference of 5% in the pH, in which the soft jackfruit variety demonstrated a higher pH (6.21) in relation to the pH (5.86) of the hard jackfruit. Regarding texture, the jackfruit varieties also do not differ by 5%, that is, the varieties are the same in the parameters of hardness, cohesiveness, elasticity and adhesion in all samples. As for the distances calculated at the peaks of the jackfruit skin, they showed that between the two varieties, these distances between the peaks are quite similar, that is, there is no significant difference (5%) between the varieties.

2
  • HOZANA FRANCIELLE DO NASCIMENTO BORGES
  • Nominal Classification for Determining the Geographic Origin of Cannabis: Integrating Machine Learning and Stable Isotope

  • Advisor : LUIZ ANTONIO MARTINELLI
  • COMMITTEE MEMBERS :
  • LUIZ ANTONIO MARTINELLI
  • JADER DA SILVA JALE
  • JOÃO PAULOS SENA SOUZA
  • Data: Feb 24, 2025
    Ata de defesa assinada:


  • Show Abstract
  • The aim of this research was to improve isotopic models for the geolocation of Cannabis through the integration of machine learning techniques and isotopic analysis. To achieve the intended objectives, isotopic data from isoscapes and real samples of Cannabis from different Brazilian biomes were used. The method involved bootstrap resampling to generate pseudo-samples and the application of classification algorithms, including Naive Bayes, Random Forest, and Neural Networks. The results demonstrated that the algorithms used achieved high accuracy rates in classifying samples by biome, with the combination of methods proving to be an efficient strategy for tracking. It was concluded that among the chosen classifiers, the Support Vector Machine (SVM) showed the best performance both in terms of sample size (from 50 to 500), using the sigmoid kernel function, and in percentage (5% to 95%), in this case using the polynomial kernel. The SVM model with kernel functions achieved the highest average accuracy (0.7970), reinforcing its overall effectiveness even with reduced samples. Meanwhile, the polynomial SVM model reached an average accuracy of 0.8036, the highest among all evaluated models with varying percentages, and stood out for its balance between precision and recall. Thus, the results highlight that the integration of isotopic analysis with machine learning provides significant contributions to forensic science, enabling greater control over drug trafficking and important advances in knowledge about Brazil's biomes.

3
  • INGRID DE ARAÚJO FELIX
  • Development of Artificial Neural Networks with Adaptive and Trainable Activation Functions Applied to Continuous Time Series Analisys

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • JADER DA SILVA JALE
  • PAULO SALGADO GOMES DE MATTOS NETO
  • Data: Feb 26, 2025
    Ata de defesa assinada:


  • Show Abstract
  • The use of artificial neural networks (ANNs) to solve complex mathematical problems, such as ordinary differential equations (ODEs) and partial differential equations (PDEs), has gained prominence in recent years. In particular, ANNs with adaptive and trainable activation functions have shown promise by automatically adjusting their properties during training, improving both convergence and accuracy. However, the effectiveness of these networks in stochastic differential equations (SDEs) is not yet fully understood. This research investigates the performance of adaptive activation functions, focusing on the Universal Activation Function (UAF), and compares it with GLN-Mish and GLN-ReLU. To this end, four important SDEs in physics and finance were solved, including the Langevin equation and the Cox-Ingersoll-Ross equation, as well as the Brownian motion equation and an exponential equation, using tools from the NeuroDiffEq library in Python. For the Langevin equation, for example, the ANN was able to converge to the analytical solution with few code adjustments, i.e., few training epochs, while for the Cox-Ingersoll-Ross equation, it initially showed some convergence difficulties. However, the neural network was still able to solve the equation, even with the interference of the stochastic term. The results show that, although the activation functions have initial convergence difficulties, they eventually approximate the analytical solution efficiently. Additionally, the analysis of Mean Squared Error (MSE) values and the behavior of the confidence interval reinforces the effectiveness of ANNs with adaptive and trainable activation functions. The ability of these activation functions to dynamically adjust to the specific demands of complex problems offers new perspectives for future research, highlighting their potential not only in solving differential equations but also in a wide range of scientific and financial applications.

4
  • MIRIAM LECÍLIA FARIAS RIBEIRO
  • Comparison between classical geostatistical methods and machine learning in the construction of foliar carbon and nitrogen isoscapes of Brazilian tree species

     

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • ANTONIO SAMUEL ALVES DA SILVA
  • JOÃO PAULOS SENA SOUZA
  • Data: Feb 26, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Atoms are the fundamental building blocks that make up matter and form the basis of everything we observe in the universe. They are composed of protons, neutrons, and electrons. Isotopes are versions of a chemical element (a set of atoms) that share the same number of protons in the atomic nucleus but differ in the number of neutrons. They can be classified into different categories based on their characteristics, including stable, radioactive, natural, artificial, cosmogenic, and industrial. The use of stable isotopes is based on the fact that the isotopic ratio is altered by biogeochemical processes that govern the movement of carbon, nitrogen, and water compounds between soil-plant-atmosphere systems. This alteration in the relative abundance of isotopes is called fractionation or isotopic discrimination, which is usually caused by a kinetic effect due to the small mass difference between the heavy and light isotope. The isotopic methodology consists of creating isoscapes from georeferenced isotopic compositions. Many studies use traditional spatial modeling and geostatistical techniques, such as spatial autoregressive regressions and Kriging methods. However, recent research indicates that machine learning (ML) algorithms, such as Random Forest (RF), provide more accurate results than previous methodologies. The importance of this technique has led to the incorporation of stable isotopes into the routine investigations of various security agencies worldwide and to the creation in 2002 of the Forensic Isotope Ratio Mass Spectrometry Network (FIRMS), which brings together academics, forensic experts, private companies, and government agencies working in this field of application. The objective of this study is to generate isoscapes of δ13C and δ15N from C3 plants for Brazil using geostatistical techniques and, mainly, machine learning to improve the accuracy of geographic isotopic patterns. This work used a dataset with 6,480 leaf samples from trees in 57 georeferenced field plots distributed throughout the Brazilian territory. The δ13C and δ15N isoscapes showed spatial patterns consistent with eco-physiological predictions in ML techniques. There are several potential applications for the isoscapes proposed here. One of them is to track the illegal wildlife trade (IWT), illegal logging, and the certification of natural products related to flora.

5
  • FRANCISCO GUSTAVO DA SILVA
  • CHARACTERIZATION OF MASS DYNAMICS OF Sargassum spp. THROUGH MULTIFRACTAL ANALYSIS IN SEGMENTED ORBITAL PRODUCTS

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • TATIJANA STOSIC
  • VINCENT VANTREPOTTE
  • Data: Feb 27, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Brown algae, known as Sargassum spp., are native to the North Atlantic and play a fundamental role in ocean dynamics. However, since 2011, large and exacerbated aggregations have been reported outside their region of origin. This dissertation sought to study these aggregations using segmented products from Sentinel 3 satellite images of the OLCI sensor with 300 meters of spatial resolution of the Mid-Atlantic region (CWA), using multifractal analysis, in 166 images for the dates 2020/01/02 to 2020/02/08, for the year 2020; 2021/04/01 to 2021/06/14, for the year 2021; 2023/06/01 to 2023/06/30, for the year 2023; and 2024/03/01 to 2024/03/30, for the year 2024. We also partitioned each image into 289 parts and applied multifractal analysis in order to extract the multifractal parameters of the singularity spectrum, width (∆α), dominant singularity (α0) and asymmetry index (f (∆α)), as well as lacunarity (Λ) and to make spatial distribution maps. The results show that the segmented images are multifractal, with Dq following D0> D1> D2 and a parabolic curve for the singularity spectrum, reflecting the interactions of Sargassum spp. over time, from low coverage in 2020 to high coverage in 2024, expressing the flowering phenomenon of these individuals. The partitions were also found to be multifractal, expressing different values in each portion of the images, allowing us to draw up the distribution of their parameters, where we could see a structure very similar to vortices, with a smaller spectral width, less lacunarity, an asymmetry to the left and greater dominant singularity, indicating that it is possible to identify the influence of the phenomena that govern the processes of ocean dynamics on different scales, even in segmented and binarized images.

6
  • CARLOS EDUARDO NEVES DE OLIVEIRA
  • Overview of Animal Protein Beef, Chicken, and Pork in Brazil (1997 to 2023)

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • ALEXANDRE FERREIRA DE LIMA
  • ANTONIO SAMUEL ALVES DA SILVA
  • GUILHERME ROCHA MOREIRA
  • Data: Feb 28, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Brazil is recognized as one of the world's largest producers and exporters of animal protein. From an environmental perspective, cattle farming faces challenges related to deforestation and greenhouse gas emissions, while poultry and swine farming require greater efficiency in water resource use and waste management. The adoption of sustainable practices has proven essential to reducing environmental impacts and meeting international market demands. This research aimed to investigate animal protein production in Brazil from 1997 to 2023, focusing on beef, chicken, and pork. The data used in the study were obtained from IBGE (SIDRA) and analyzed using the R software, employing statistical models, including the modified Mann-Kendall test and Sen’s Slope test. The results indicated continuous growth in chicken meat production, surpassing beef from 2004 onwards, driven by lower production costs and greater acceptance in the international market. Pork production also expanded, stimulated by increased Chinese demand due to the African Swine Fever outbreak. The analysis revealed fluctuations that significantly impacted meat production and consumption, particularly in 2008, 2014, 2017, and 2020, due to the global financial crisis, adverse climate events, internal economic instabilities, trade wars, and logistical restrictions resulting from the COVID-19 pandemic. Brazil plays a central role in global food security.

7
  • LETÍCIA SOUZA DE OLIVEIRA
  • Development of a new triparametric model: properties and applications to economic data

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • FRANK SINATRA GOMES DA SILVA
  • FIDEL ERNESTO CASTRO MORAES
  • THIAGO ALEXANDRO NASCIMENTO DE ANDRADE
  • Data: Feb 28, 2025
    Ata de defesa assinada:


  • Show Abstract
  • This work presents the development of a new three-parameter probabilistic model, named $\Gamma$-MK, designed to model data restricted to the unit interval, such as rates and proportions. The model combines the gamma-G generator with the Modified Kumaraswamy distribution, offering greater flexibility and accuracy in data analysis within this interval. The primary motivation is the need for more adaptable models to describe various phenomena. The proposed model stands out for its high flexibility and computational simplicity, with all mathematical expressions efficiently treatable, facilitating its practical application in different contexts. Simulation studies were conducted using five estimation methods: maximum likelihood, least squares, maximum product spacing, Anderson–Darling, and Cramér–von Mises. The results indicated that the estimates exhibited consistent behavior across methods, with biases decreasing as sample size increased, demonstrating the model's robustness and feasibility for practical applications. An application to real-world data was performed using the Gini index of 61 countries, analyzed in a cross-sectional format for the period from 2005 to 2019. To handle missing data, the supervised machine learning method \textit{K-Nearest Neighbors} was employed, preserving the empirical distribution of the original data. The descriptive analysis revealed stability in inequality indices over the years, while the $\Gamma$-MK model adjustments showed superior performance compared to classical distributions, such as beta and Kumaraswamy, in $87\%$ of the evaluated scenarios. Goodness-of-fit metrics, such as Akaike Information Criterion, Bayesian Information Criterion, Corrected Akaike Information Criterion, Kolmogorov-Smirnov, Anderson–Darling, and Cramér–von Mises, corroborated the superiority of the proposed model. Additionally, we present mathematical properties of the proposed model, including density expansion, quantile function, ordinary moments, skewness, kurtosis, reliability, and entropy. The model's flexibility allows capturing different patterns of skewness and kurtosis, making it particularly useful for economic data and variables restricted to the unit interval. The analysis of the Lorenz curve and the Gini index further reinforced the model's potential to assess income inequalities.

8
  • SUELEN REGINA DA SILVA LIMA FERRAZ
  • APRENDIZADO DE MÁQUINA COMO FERRAMENTA DE RESOLUÇÃO PARA EQUAÇÕES DIFERENCIAIS ESTOCÁSTICAS

     

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • ANTONIO DE PADUA SANTOS
  • PAULO RENATO ALVES FIRMINO
  • Data: Feb 28, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Using neural networks to solve differential equations is an advantageous approach for analyzing continuous-time series due to their ability to handle the inherent nonlinearities and complexities of time series data. This approach enables the model to learn and adapt to the underlying properties of the system, enhancing flexibility and efficiency in the analysis and prediction of complex phenomena. In this work, we propose an application of the Euler-Maruyama method using three neural network architectures: Extreme Learning Machines (ELMs), Multi-Layer Perceptrons (MLPs), and Recurrent Neural Networks (RNNs). These networks are employed to solve a set of stochastic differential equations characterized by the Wiener process. The Euler-Maruyama scheme is utilized to discretize the stochastic equations, transforming them into a suitable form for neural network training. Empirical results demonstrate the effectiveness of this approach in accurately and efficiently solving stochastic differential equations.

     

9
  • EDUARDO GOMES DE ARAÚJO
  • Impact of prey evolution and spatial heterogeneity on the dynamics of a predator-prey system

     

  • Advisor : VIVIANE MORAES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • NATHAN LIMA PESSOA
  • PEDRO HUGO DE FIGUEIREDO
  • VIVIANE MORAES DE OLIVEIRA
  • Data: May 26, 2025
    Ata de defesa assinada:


  • Show Abstract
  • The mathematical study of the interaction between prey and predator populations began with the
    research conducted by Lotka and Volterra. Since then, prey-predator systems have been modeled using a
    wide range of mathematical and computational techniques. Through the use of these techniques, it is
    possible to simulate the interactions between prey and predators to understand the behavior of an ecosystem and how this behavior spatially affects the system. In this context, we employ a computational
    model that considers prey-predator interactions in a heterogeneous habitat, with resources distributed
    according to a fractal landscape generated by fractional Brownian movement, which allows the regulation
    of terrain roughness through the Hurst exponent, H. The computational model used in this study employs
    a two-dimensional environment using the Von Neumann neighborhood, which enables an individual at a
    given site to interact with its four closest neighbors. The prey species are defined by a set of half-
    saturation constants for different resources, modeled by a Gaussian distribution, representing their
    efficiency in utilizing each resource. The model considers prey survival, reproduction, and mutation, as
    well as predator predation and reproduction. The probability of prey reproduction depends on resource
    availability and is described by an adaptation of Monod’s equation, following Liebig’s Law of the Minimum.
    The system is initially composed of a single prey species, and new species emerge through mutations,
    occurring with a probability υ, simulated by alterations in the half-saturation constants inherited from the
    parent. Based on the results obtained, the dynamics of prey and predator populations are strongly
    influenced by the probability of predator reproduction (rp), the prey mutation rate (υ), and the
    heterogeneity of resources represented by the landscape (H). For low predator reproduction rates (rp =
    0.01), prey occupy most of the network, leading to predator extinction. With an increase in rp (rp = 0.1 and
    rp = 0.2), we observe the coexistence of both species, but even higher values of rp result in successive
    extinctions. Prey species diversity is higher under low predator reproduction rates and high mutation
    rates, while more heterogeneous terrains (H 0) generally support fewer species. The species abundance→
    distribution also reflects this dynamic, showing high diversity under high mutation and low predator
    reproduction, but a concentration of a few dominant species as predator reproduction increases and
    mutation rates decrease.

     

     

10
  • RAFAELLA SANTOS BESERRA
  • Analysis of the seasonality of the rainfall regime in the state of Paraíba, Brazil

  • Advisor : ANTONIO SAMUEL ALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • TATIJANA STOSIC
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: May 27, 2025
    Ata de defesa assinada:


  • Show Abstract
  • The analysis of rainfall seasonality is crucial as it enables the detection of trends and climate changes on local or regional scales. This not only facilitates the sustainable management of natural resources but is also essential for mitigating environmental risks and improving the quality of life of affected populations. The main objective of this study is to analyze the rainfall regimes of Paraíba, a state in northeastern Brazil, based on the calculations of the individual seasonality index (SIi) and the general seasonality index (SI), as well as the replicability index (RI). To achieve this goal, daily precipitation data recorded at 130 rain gauge stations over the period from 1994 to 2020 were analyzed. These data were made available by the Executive Agency for Water Management of Paraíba (AESA). The modified Mann-Kendall test and Sen’s slope estimator were applied to investigate trends in the SIi time series. Additionally, the Inverse Distance Weighting (IDW) interpolator was used to perform the spatial analysis of precipitation. The results indicated that the Zona da Mata is the region of the state with the highest rainfall indices, followed by the Agreste, where the rainy season begins in March and extends until June, characterized by strong seasonality and a short dry season. In the Borborema region, the SIi index revealed extreme seasonality, with almost all precipitation concentrated within just one to two months. Meanwhile, the Sertão, in the western portion of the state, exhibited a moderate but markedly seasonal rainfall regime, with a long dry season. Regarding the replicability index, the results suggest that the Sertão has the most consistent rainfall regime in the state. Stations with significant positive trends are predominantly located in the Agreste and Borborema regions. The relationship between the SIi index and longitude was also investigated. The results revealed a significant linear correlation, with a coefficient of r = -0.81. This suggests that the farther a region is from the ocean, the higher its seasonality index.

11
  • SÓSTENES JERÔNIMO DA SILVA
  •  WIND ENERGY GENERATION POTENTIAL IN NORTHEAST BRAZIL USING DISTRIBUTIONS MIXTURES

  • Advisor : JADER DA SILVA JALE
  • COMMITTEE MEMBERS :
  • JADER DA SILVA JALE
  • JOSIMAR MENDES DE VASCONCELOS
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Jun 30, 2025
    Ata de defesa assinada:


  • Show Abstract
  • This work evaluates the potential for wind power generation in the Northeast region of Brazil by adjusting statistical models based on mixtures of distributions. Wind speed series from nine meteorological stations, representing each state of the region, were analyzed. The methodology involved the application of an algorithm capable of testing several combinations of distributions and selecting the best models based on information criteria (AIC, BIC, HQ), error metrics (MAE, MSE, RMSE, MAPE), statistical adherence (Anderson-Darling and von Mises) and visual evaluation. The results show that, in locations with bimodal behavior, mixtures offer superior adjustments compared to simple distributions, allowing more accurate estimates of wind potential. The highest potential values were found at the stations of Calcanhar-RN, Arembepe-BA and Arapiraca-AL. It is concluded that the proposed approach is efficient in modeling wind variability and useful as a tool to support wind energy planning.

     

Thesis
1
  • RUBEN VIVALDI SILVA CARNEIRO PESSOA
  • CORRELATIONS BETWEEN TIME SERIES OF VEGETATIONS FIRES AND CLIMATE VARIABLES IN BRAZILIAN BIOMES

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • TATIJANA STOSIC
  • JADER DA SILVA JALE
  • MOACYR CUNHA FILHO
  • IKARO DANIEL DE CARVALHO BARRETO
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Jan 16, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Forest fires are complex phenomena, influenced by climatic factors, in addition to human interference. In Brazil, fires affect all biomes. Therefore, the study of these fires is necessary due to their negative effects, including not only environmental damage, but also greenhouse gas emissions and economic losses. In this scenario, understanding the temporal distribution of fires is challenging, due to the variation in their natural behavior. This study seeks to address this issue, using fractal techniques to analyze the long-term temporal and spatial correlations between fires and climate variables in Brazilian biomes during the period from 2002 to 2022. The results for the Amazon, Caatinga, Cerrado, and Atlantic Forest biomes showed that in the daily series of fire anomalies and climate variables (relative humidity, maximum temperature, rainfall, and wind speed), there are persistent long-range correlations, in which the persistence of fires was strongest in the Amazon biome and weakest in the Atlantic Forest. Climate variables are more persistent in the Caatinga biome and less persistent in the Atlantic Forest. Furthermore, persistent long-range cross-correlations were observed between the series of climate variables and fires in the four biomes. For the Amazon, Caatinga and Cerrado biomes, the DCCA correlation coefficient values indicated positive correlations between fires and the maximum temperature and wind speed variables, and negative correlations between fires and the relative humidity and rainfall variables. For the Atlantic Forest biome, the correlations between fires and the maximum temperature variable were positive and negative for the other climate variables.

2
  • VANIÉLE DA SILVA BARROS
  • Use of Recurrence Chart in analyzing correlations between prices of agricultural products and exchange rate

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • TATIJANA STOSIC
  • ANTONIO SAMUEL ALVES DA SILVA
  • JADER DA SILVA JALE
  • LIDIANE DA SILVA ARAUJO
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Feb 11, 2025
    Ata de defesa assinada:


  • Show Abstract
  • This study investigates the influence of the Subprime crisis and the COVID-19 pandemic on the nonlinear dynamics of Brazilian agricultural commodity prices (sugar, soybeans, cattle, cotton, coffee) and their relationship with the Dollar/Real exchange rate, using Recurrence Plot (RP), Cross Recurrence Plot (CRP), Recurrence Quantification Analysis (RQA), and Cross Recurrence Quantification Analysis (CRQA) methods. The data used consist of daily prices of Brazilian agricultural commodities and the exchange rate, recorded between July 1997 and May 2023, provided by the Center for Advanced Studies on Applied Economics / Luiz de Queiroz College of Agriculture / University of São Paulo (CEPEA/ESALQ/USP). The RPs of the time series for commodity prices (BRL) during the pre- and post-Subprime crisis periods and the pre-pandemic and pandemic periods showed that price dynamics are not random. Checkerboard patterns and white bands were observed, indicating sudden changes and non-stationarity. Moreover, the texture of the plots revealed chaotic behavior and short-lived laminar states. During the pandemic, the prices of sugar, coffee, cotton, and soybeans became more predictable, while cattle price predictability decreased. RQA metrics indicated increases in REC, DET, and L indices for some commodities, suggesting higher predictability and lower market efficiency. In contrast, the exchange rate exhibited greater efficiency, reflected in reduced price predictability. In the post-Subprime crisis period, the prices of sugar, cotton, cattle, and coffee also became more predictable, whereas soybeans and the exchange rate showed lower predictability. CRQA analysis revealed a reduction in synchronization between the studied agricultural commodity markets and the exchange rate during the pandemic, suggesting decreased predictability and interaction. In the post-Subprime crisis period, synchronization between the exchange rate and sugar and cattle prices also declined. However, there was an increase in synchronization between the exchange rate and cotton, coffee, and soybean prices. These analyses provide valuable insights for policymakers, companies, investors, and risk managers, aiding them in making informed decisions and developing effective strategies in a globally interconnected and volatile economic environment.

3
  • LUCAS SILVA DO AMARAL
  • Growth modeling and analysis of critical points of Lion Head rabbits and Zebu x Taurino cattle in confinement

     

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • GUILHERME ROCHA MOREIRA
  • ANTONIO SAMUEL ALVES DA SILVA
  • FRANK SINATRA GOMES DA SILVA
  • DAMOCLES AURELIO NASCIMENTO DA SILVA
  • JOÃO DE ANDRADE DUTRA FILHO
  • Data: Feb 13, 2025
    Ata de defesa assinada:


  • Show Abstract
  • This study aimed to model growth curves of Lionhead rabbits and Zebu x Taurine cattle subjected to diets with different protein levels and feeding regimes, respectively. For the rabbits, 32 animals were distributed into four groups with diets containing 13%, 16%, 19%, and 22% crude protein, evaluated weekly between 73 and 192 days of age. Five nonlinear models (Brody, Gompertz, Logistic, Richards, and von Bertalanffy) were fitted to the data. According to evaluation criteria combined with cluster analysis, the von Bertalanffy model was deemed the most appropriate. Subsequently, a curve identity test and an analysis of critical points (inflection point (IP), maximum acceleration point (MAP), maximum deceleration point (MDP), and asymptotic deceleration point (ADP)) were performed. The curve identity test indicated significant differences between the diets (p < 0.05), except for performance between the 16% and 19% protein diets. The analysis of critical points revealed that rabbits fed the 13% protein diet exhibited slower development, whereas those on the 22% protein diet reached growth stabilization more quickly. The comparison of treatments demonstrated that the 16% protein diet provided the best performance in terms of animal health. In the study with cattle, symmetric nonlinear models were fitted to the accumulated weight gain of 24 animals, which were divided into three feeding regimes: no adaptation protocol (CON), with adaptation protocol (ADP), and extruded diet (EXT). Weight gain was monitored daily over 144 days. The fitted models included Brody, Gompertz, Logistic, Santos, and von Bertalanffy, and the distributions analyzed were Normal, t-Student, Exponential Power, Cauchy, Logistic I, and Logistic II. The von Bertalanffy model fitted with a t-Student distribution with 3 degrees of freedom proved to be the most effective from both statistical and biological perspectives. Regarding feeding regimes, the ADP diet stood out, showing higher absolute growth rates and greater growth acceleration, outperforming the CON and EXT diets. In summary, the analysis of critical points of the growth curves provided valuable insights for more precise nutritional interventions, and the application of symmetric distributions was crucial for handling data with outliers, enhancing the robustness of the analyses. These findings can contribute to more effective nutritional management practices, with implications for both companion animals and meat production.

4
  • JOSÉ EDVALDO DE OLIVEIRA NUNES
  • Analysis of complex price networks of Brazilian agricultural commodities using the horizontal visibility graph method

  • Advisor : BORKO STOSIC
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • BORKO STOSIC
  • JOSÉ DOMINGOS ALBUQUERQUE AGUIAR
  • LIDIANE DA SILVA ARAUJO
  • LUCIAN BOGDAN BEJAN
  • Data: Feb 18, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Agricultural commodities are directly associated with agribusiness and play a fundamental role in the Brazilian economy. These products can be considered the most important, as their prices have a significant effect on the population's quality of life. Understanding the behavior of agricultural commodity price series is a challenge, due to the complexity of the market and the abrupt changes resulting from global crises. The methods currently applied to analyze nonlinear time series still present a high computational cost, requiring simpler and faster methods to extract information from the process that generated them, with the aim of understanding, modeling and forecasting. Motivated by this, we propose to apply the Horizontal Visibility Graph (HVG) method to analyze the temporal variation of the prices of Brazilian agricultural commodities. The data were provided by the Center for Advanced Studies in Applied Economics (CEPEA) of the Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo (USP) and divided into two groups: (i) ethanol and sugar, in relation to the COVID-19 pandemic, with records between January 2017 and May 2023; and (ii) sugar, cotton, cattle, soybeans, and coffee, in relation to the 2007/2008 financial crisis and the COVID-19 pandemic, covering the periods from May 2003 to September 2011 and from January 2017 to May 2023. The HVG, based on the theory of complex networks, maps a time series onto a graph, assigning each data point in the series to a node. The software used was VisGraAnalysis, developed in C programming language. The main idea is to study to what extent the techniques and focus of graph theory are useful as a way to characterize time series. The following network indices were calculated: clustering coefficient, transitivity, average shortest path length, degree distribution, and Kullback-Leibler divergence to identify the irreversibility of the series. The main results indicated that the HVG positively captures the structural properties of the networks, and price variations reflect changes in market dynamics in the face of global crises. The relationship between ethanol and sugar was analyzed, identifying the sugar market (in BRL) as more efficient and the ethanol market as less efficient during the COVID-19 pandemic. For the second group, lower efficiency was observed in the period before the 2007/2008 crisis, except for soybeans. Coffee showed greater sensitivity to the 2007/2008 crisis, while sugar and cattle showed increased efficiency during the pandemic (the value of λ decreased, indicating a less correlated series).

5
  • DENISE STEPHANIE DE ALMEIDA FERREIRA
  • Prediction of hydraulic resistance to interrule erosion under shallow laminar flow using GLM and GAMLSS modeling

     

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • JOSIMAR MENDES DE VASCONCELOS
  • ANTONIO CELSO DANTAS ANTONINO
  • JOSÉ ADALBERTO DA SILVA FILHO
  • LUIZ MEDEIROS DE ARAÚJO LIMA FILHO
  • Data: Feb 24, 2025
    Ata de defesa assinada:


  • Show Abstract
  • The combination of different types of vegetation cover significantly changes hydraulic properties, thereby controlling soil erosion. Generalized Linear Models (GLMs) form one of the most popular classes of statistical models and can provide accurate predictions by establishing a link function to linearize the deterministic relationship between the predictor and response variables. Furthermore, Generalized Additive Models for Location, Scale, and Shape (GAMLSS) are more refined distributional regression models that allow flexible regression and smoothing adjustments to data. In the present study, GLM modeling was performed using Gaussian and Gamma distributions, while GAMLSS modeling was conducted with Skew Exponential Power (SEP), Sinh-Arcsinh (SHASH), Johnson's Su (JSU), and Skew t (ST) distributions to determine the relationship between the Reynolds number (Re) and the Froude number (Fr) in the Darcy-Weisbach coefficient (f), which is frequently used to estimate hydraulic resistance to inter-rill erosion under different vegetation cover conditions. For GLM, in the univariate approach, the Froude number demonstrated superiority in explaining hydraulic resistance behavior in shallow surface flows. However, to improve the prediction model's accuracy, other variables were incorporated, such as water flow depth (h), unit discharge (q), and soil loss (SL). Diagnostic analyses were performed to evaluate the goodness-of-fit of the Gamma model with a logarithmic link function to the surface runoff database. In the GAMLSS analysis, the Froude number also demonstrated superiority in predicting hydraulic resistance, along with variables such as sediment concentration (C_s), rainfall intensity (I), infiltration rate (Inf.rate), runoff coefficient (C), mean flow velocity (V_m), h, inter-rill detachment rate (D_i), PS, and vegetation drag coefficient (CD), with an emphasis on the SEP type 4 distribution. The results demonstrated that the predictor variables were significant, and the Gamma modeling with a logarithmic link function (for GLM modeling) and SEP4 (for GAMLSS modeling) were satisfactory in accurately predicting the Darcy-Weisbach resistance coefficient (f) under different types of vegetation cover and bare soil conditions.

6
  • JOELMA MAYARA DA SILVA
  • Analysis of nonlinear dynamics from precipitation and drought indices in Pernambuco using the horizontal visibility graph

  • Advisor : BORKO STOSIC
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • BORKO STOSIC
  • JOSÉ DOMINGOS ALBUQUERQUE AGUIAR
  • LUCIAN BOGDAN BEJAN
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Feb 28, 2025
    Ata de defesa assinada:


  • Show Abstract
  • Recent climate changes driven by global warming have altered precipitation patterns across multiple regions of the planet. Droughts and floods have become more frequent, particularly in tropical countries how to Brazil. In this context, this study aims to analyze the dynamics of precipitation and the Standardized Precipitation Index (SPI) in the Pernambuco state. For this, the Horizontal Visibility Graph (HVG) method was applied. Particularly, the study utilized the Clustering Coefficient (C), the Average Shortest Path Length (L), and the slope of the semi-logarithmic degree distribution (λ). The HVG was applied to time series of precipitation (originals and anomaly) and the Standardized Precipitation Index at 1, 3, 6, and 12 month scales, using data from five representative stations across Pernambuco’s mesoregions: Metropolitan Region (Recife), Zona da Mata (Vitória de Santo Antão), Agreste (Jucati), Sertão Pernambucano (Serrita), and Sertão São Francisco (Petrolina), in the period from 1962 to 2012. The calculated indices enabled the identification of similarities and differences in the rainfall generating processes across the state's mesoregions, allowing for the distinction between chaotic and stochastic regions based on the λ coefficient. Additionally, the results revealed variations in the connectivity (C) and integration (L) properties of the networks derived from precipitation and anomaly series. A similar pattern was observed for the Standardized Precipitation Index, indicating distinct behaviors across different temporal scales (1, 3, 6, and 12 months). Furthermore, 133 rainfall stations distributed throughout Pernambuco were analyzed over the same period and grouped into three climatic regions: Zona da Mata (humid climate), Agreste (transition zone), and Sertão (semi-arid climate). The Mann-Kendall test was employed to assess significant differences among these regions based on the calculated indices. The test confirmed significant differences in the C and L indices but failed to distinguish the climatic regions significantly based on the λ coefficient, for both precipitation and anomaly series. Thus, the analysis of topological indices derived from the constructed networks provides valuable insights into the processes governing precipitation and the Standardized Precipitation Index.

7
  • ELAINE CRISTINA MOREIRA MARQUES
  • Automatic extraction of factors related to university dropout: case study in Agricultural Sciences courses at UFRPE

  • Advisor : WILSON ROSA DE OLIVEIRA JUNIOR
  • COMMITTEE MEMBERS :
  • FELIPE DWAN PEREIRA
  • GABRIEL ALVES DE ALBUQUERQUE JUNIOR
  • JOÃO AGNALDO DO NASCIMENTO
  • RAFAEL FERREIRA LEITE DE MELLO
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • Data: May 23, 2025
    Ata de defesa assinada:


  • Show Abstract
  • University dropout is a complex phenomenon that directly impacts higher education institutions and students, leading to financial resource waste and hindering young people's academic and professional development. At the Federal Rural University of Pernambuco (UFRPE), dropout rates in Agricultural Sciences programs pose a significant challenge, requiring the identification of key factors contributing to early withdrawal. To deepen this analysis, this study adopts a counterfactual inference approach, allowing for the estimation of causal impacts of different variables on dropout rates. By applying counterfactual modeling techniques, alternative scenarios were analyzed to determine which factors increase or decrease students' chances of retention. The results indicate that the number of accumulated course approvals in the first semesters significantly influences academic retention, suggesting that academic support strategies can effectively reduce dropout rates. The proposed approach strengthens university administrators' decision-making processes, providing data-driven insights to enhance educational policies aimed at improving student retention.

8
  • NATÁLIA MORAES CORDEIRO
  • Generalized Complementary Baseline Classes

  • Advisor : WILSON ROSA DE OLIVEIRA JUNIOR
  • COMMITTEE MEMBERS :
  • CICERO CARLOS RAMOS DE BRITO
  • KLEBER NAPOLEAO NUNES DE OLIVEIRA BARROS
  • MOACYR CUNHA FILHO
  • RONALDO VENACIO DA SILVA
  • WILSON ROSA DE OLIVEIRA JUNIOR
  • Data: Jul 18, 2025


  • Show Abstract
  • This research aims to present two generalized complementary and bibaseline classes, referred to as the Generalized Sine Bibaseline Complementary Class and the Generalized Beta Bibaseline Complementary Class, respectively. These classes generalize and generate probability distributions through the composition of functions, enabling the identification of new probabilistic distributions, distribution classes, and families of probability distributions. Based on the proposed idea, expansions for the cumulative distribution function and the probability density function were developed. The characterization properties of the classes and their respective expansions were presented, including risk function, moments, central moments of order m, moment-generating function, characteristic function, and general coefficient. Additionally, the derivatives of the log-likelihood function and a study of the support were conducted. A theoretical application of each class was also carried out, followed by an application to simulated data, as well as a real data set, comparing the proposed model with other existing models and thereby evaluating its potential relative to the others.

     

2024
Dissertations
1
  • NICÉIAS SILVA VILELA
  • Use of Visibility Graph for analisys of soil computerized tomography images

  • Advisor : BORKO STOSIC
  • COMMITTEE MEMBERS :
  • BORKO STOSIC
  • JOSÉ DOMINGOS ALBUQUERQUE AGUIAR
  • LUCIAN BOGDAN BEJAN
  • Data: Feb 23, 2024


  • Show Abstract
  • Soil has been increasingly studied due to its structure playing a vital role in sustainable food production and the well-being of society, mainly. In this sense, there is a growing search for a more holistic approach to land use and management to deal with the increasing pressure on soil resources for the production of food and, at the same time, reduce the adverse environmental impacts of agricultural practices. Such structure, which can be described as the spatial arrangement or heterogeneity of soil particles, aggregates and voids or pores, determines the functionality and sustainability of this living natural entity essential for the earth to fulfill its function. Recent advances in non-destructive imaging techniques, such as X-ray computed tomography (CT), make it possible to examine pore space characteristics through direct observation of soil structure. A quantitative characterization of the three-dimensional architecture of soil morphology is crucial to understanding soil mechanics as it relates to the control of biological, chemical, and physical processes at all scales. Despite improvements in the resolution of computed tomography equipment and computational power, there is no consensus on data analysis methods that allow revealing the complexity of all elements associated with 3D soil images, especially methods that do not require a threshold to segment images. In this work, we propose an approach to study the morphological properties of soil and analyze changes in soil structure due to the disturbance caused by current sugarcane management techniques, which causes changes in its structure, mainly in the upper layer; for this, we use the Visibility Graph (VG) and Horizontal Visibility Graph (HVG) methods, based on the theory of complex networks, which converts time series into graphs through a geometric visibility criterion that associates each data in the time series to a node in the visibility graph. To date, these two methods have not been used in 3D image analysis. Analysis of the changes occurring in the structure is possible by comparing computed tomography images of the soil with Atlantic Forest and sugar cane coverage. VG and HVG are applied to columns of voxels in the gravity direction (Z) producing the planar (XY) distribution of topological indices. For each column of voxels VG and HVG networks were generated, and the Clustering Coefficient C, the Average Shortest Path Length ⟨d_ij ⟩, and the Average Degree ⟨k⟩ were calculated, which are indices used to describe the network topology. Promising results were obtained with two soil samples, the first of which consists of a computerized image of soil with Atlantic Forest cover, and another of sugar cane, both with a depth of 0-10cm, were used to show the efficiency of the methods applied. In terms of comparing the application of the HVG and VG methods both performed for each vertical column of voxels proved to be efficient and produced very competitive results. The index Average shortest path length of the HVG network and the Average degree of the VG network showed the greatest difference between the samples, showing that these indices are efficient and suitable for quantifying the degradation of soil morphological properties caused by changes in vegetation cover.

2
  • MATHEUS DIAS AGUIAR
  • Use of Recurrence Graph in the analysis of the time series of fires in the Amazon biome

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • TATIJANA STOSIC
  • LUCIAN BOGDAN BEJAN
  • IKARO DANIEL DE CARVALHO BARRETO
  • Data: Feb 27, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The increase in fires activity in the Amazon is a topic of great relevance and concern. Various studies indicate that agricultural intensification and extreme weather conditions such as severe droughts are directly linked to a substantial increase in fires associated with deforestation in the region. This study aims to investigate the temporal variability of fires, establishing correlations with climatic variables in the Amazon biome. To achieve this purpose, the Recurrence Plot (RP), Cross-Recurrence Plot (CRP), Recurrence Quantification Analysis (RQA) and Cross- Recurrence Quantification Analysis (CRQA) methods were used. These methods were developed to analyze the nonlinear dynamics of time series. The studied period is 07/04 2002 – 07/31/2020, the fire data are hot pixels detected by the reference satellite AQUA_M-T, made available by the National Institute for Space Research – INPE, and the data of climate variables (precipitation , maximum temperature, relative humidity and wind speed) are generated from Brazilian Daily Weather Gridded Data (BR-DWGD). The RP/RQA results showed that among the climatic variables, relative humidity presents a more predictable and stable dynamic, while precipitation presents a less predictable and less stable temporal variability. The RQA indices for the fires were closer to the RQA indices for relative humidity. The CRP/CRQA results showed that among the climatic variables, the dynamics of the fires presents a synchronization with relative humidity that is more predictable and more stable, while the synchronization is less predictable and less stable with precipitation. These results highlight the importance of considering not only isolated fire events, but also seasonal climate conditions that can significantly influence fire dynamics in the region.

3
  • IÊDA MARIA DE SIQUEIRA BEZERRA
  • Comparison of Statistical Methods Applied in Repeated Measures Over Time in Forestry Experimentation

  • Advisor : JOSE ANTONIO ALEIXO DA SILVA
  • COMMITTEE MEMBERS :
  • GILCIANO SARAIVA NOGUEIRA
  • GUILHERME ROCHA MOREIRA
  • JOSE ANTONIO ALEIXO DA SILVA
  • Data: Feb 29, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The objective of this research was to evaluate the height growth of forest species, cultivated in an agroforestry system, including two clones of Eucalyptus (Eucalytpus urophylla × Eucalytpus tereticornis), Aroeira (Myracrodruon urundeuva Allemão) and Angico (Anadenanthera colubrina var. Cebil), in intercrops or monocultures with an agricultural species, Cowpea (Vigna unguiculata (L) Walp.) and a forage species, Tanzânia Grass (Panicum maximum Jacq), and verify the effect of the spacings 3 m × 2 m in monoculture and 4 m × 2 m, both in monocultures and in intercrops with Tanzânia Grass and Cowpea, and also the effectiveness of the application of nutrient sources and a soil conditioner, residue from fish farming tanks, sediments from Itaparica reservoir, biochar and control, each repeated four times. The experiment is located in the municipality of Belém de São Francisco, Pernambuco, and was implemented in March 2014, at the Experimental Station of the Agronomic Institute of Pernambuco. The experimental design is multivariate with repeated measures over time. The plantings were organized in two spacings 4 m × 2 m for tree species, both in monoculture and in consortium with Cowpea and Tanzânia Grass, and with spacing of 3 m × 2 m for tree species in monoculture. The tree species were allocated to 256 plots, each containing 28 plants, 10 of which occupy the useful area. Plots with 3 m × 2 m spacing are 14 m × 12 m in size, with an area of 168 m² per plot, in 4 m × 2 m spacing they have dimensions of 14 m × 16 m, and an area of 224 m² per plot. To carry out the analysis, three statistical methods were used and compared: multivariate with repeated measurements over time, split-plot design and time-series analysis. The 4 m × 2 m spacings combined with Tanzânia Grass and Cowpeas demonstrated promising results, being the most favorable spacing options. The nutrient sources did not show statistical differences between them. The MA 2000 and MA 2001 clones stood out as the species with the greatest growth, however, the MA 2001 clone presented the highest heights in practically all periods analyzed, statistically differentiating itself from all other species. The MA 2001 clone appears to be a highly promising option for cultivation in the region, showing accelerated growth and proving to be suitable to meet local energy demands. The results highlight the relevance of choosing fast-growing species to meet energy needs, especially in semi-arid regions, where illegal logging of native species is a concern. Furthermore, this approach offers opportunities to diversify the sources of income for farmers in the semi-arid region, reducing exclusive dependence on conventional agriculture, since eucalyptus wood has significant value and is used in several sectors.

4
  • CÁREN BEATRIZ DOS SANTOS FELIX DA SILVA
  • Morphometric analysis of Caranx latus otoliths on the coast of Pernambuco - Brazil
  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • GUILHERME ROCHA MOREIRA
  • JONAS ELOI DE VASCONCELOS FILHO
  • Data: May 2, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Otoliths are calcified structures that are fundamental for hydrostatic
    balance and hearing in teleost fish. These structures provide a wealth of information that
    allows us to investigate the dynamics and life history of fish. In recent years, the analysis
    of otolith shape has been highlighted as a valuable tool for discriminating between species
    and associated estuaries. In this study, we used Fourier descriptors and multivariate
    analysis to compare the shape patterns of 389 juvenile individuals caught in five estuaries
    in northeastern Brazil: Sirinhaém, Santa Cruz de Itapissuma, Suape, Rio Formoso and
    Goiana. The otoliths differed significantly between the estuaries. MANOVA revealed
    significant differences between them (p < 0.05), especially between Suape. Sirinhaém
    and Santa Cruz de Itapissuma, although cross-validation showed a low accuracy of 38%.
    These differences in otolith shape are directly related to environmental factors, including
    freshwater and saltwater influences, as well as the impacts of anthropogenic activities.
    Thus, otolith shape analysis has emerged as an effective tool not only for differentiating
    estuaries with strictly similar phenotypic characteristics, but also for identifying stocks,
    which contributes to more efficient management of inland fisheries resources. However,
    further studies are needed to better understand the contribution of the genetic effect in
    comparison with environmental and biotic effects, in order to clarify the differences
    observed in otoliths and their relationship with the estuarine environment.

5
  • WYLLIAM EDUARDO ALVES SILVA
  • Assessment of Housing Systems for F1 Crossbred Breeding Rabbits

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • ANDRESSA NATHALIE NUNES MAGALHÃES
  • ANDRÉ LUIZ PINTO DOS SANTOS
  • CRISTIANE ROCHA ALBUQUERQUE
  • GUILHERME ROCHA MOREIRA
  • Data: May 8, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The present study aimed to evaluate housing systems for breeding rabbits and rabbits during
    the fattening period, using 24 F1 crossbreed mother rabbits (1/2 New Zealand White and 1/2
    California). The F1 crossbreed breeding rabbits were obtained from crossing New Zealand
    White and California rabbits. The experiment was conducted at the Rabbit Farming sector
    facilities at the Federal Institute Minas Gerais, Campus Bambuí, during the period from July
    2020 to February 2021. The experimental design adopted was completely randomized (CRD),
    with three different treatments (housings): T1 - Individual cage, T2 - Cage for two rabbits and
    T3 - Collective pen (four rabbits per pen). To apply the analysis of variance (ANOVA), the
    normality of the variable of interest (Y) was verified using the Shapiro-Wilk tests, as well as
    the homogeneity of variances using the Bartlett test. The productive performance of the
    rabbits was evaluated considering the parameters: weight at first insemination, final weight,
    weight at 120, 150 and 180 days of age, weight gain in the intervals from 120 to 150 days and
    from 150 to 180 days. The completely randomized design (CRD) was used for the initial
    parameters, while the other parameters followed a completely randomized split-plot design,
    with the types of housing as main treatments and the age of the does as secondary treatments.
    Reproductive performance was evaluated according to the following parameters: total number
    of births, number of live births, weight of offspring at 35 days of lactation, litter weight of
    newborns and litter weight of live births. These parameters followed a completely randomized
    split-plot design, with housing types as main treatments and cycles as secondary treatments.
    The results revealed that housing did not influence the final weight of the does, but there was
    a statistically significant difference in weight at the first insemination between the different
    types of housing. In relation to weight gain, the accommodations did not have a significant
    influence, except in the period of 120-150 days, where a significant difference in daily weight
    gain was observed between the accommodations. With regard to reproductive performance,
    housing systems did not demonstrate a significant influence on the analyzed parameters. In
    conclusion, housing systems played a significant role in improving the productive
    performance of rabbits, highlighting their remarkable influence in this context. However, it is
    important to highlight that this influence did not substantially extend to reproductive
    performance.

6
  • LUCAS CARDOSO PEREIRA
  • ENTROPY TRANSFER ANALYSIS IN AGRICULTURAL MARKET BRAZILIAN.

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • LUCIAN BOGDAN BEJAN
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • TATIJANA STOSIC
  • Data: May 22, 2024


  • Show Abstract
  • Agricultural commodities are primary products grown on a large scale, which play a
    crucial role in the global economy. Its importance is evidenced by its contribution to
    food security, international trade and the livelihoods of millions of people around the
    world, in addition to directly influencing food prices and the economic stability of many
    countries. The study was carried out with the purpose of analyzing the temporal variation
    and comparing the price dynamics of 3 groups of Brazilian agricultural commodities:
    grains, meat and soft, and to which commodity the price variation is directly related, thus
    contributing to the advancement and confirmation of theoretical and computational models
    aimed at predicting prices in this sector. For this purpose, the Network Transfer Entropy
    methodology was used. Daily price series were proven as well as the series of returns
    recorded in the period from January 2010 to August 2022, the data were obtained by the
    Centro de Estudos Avançados em Economia Aplicada/ Escola Superior de Agricultura
    Luiz de Queiroz/ Universidade de São Paulo - CEPEA / ESALQ / USP. The historical
    series of commodity prices were verified, then the return series was calculated, to finally
    apply the TE methodology. For each pair of commodities, TE was calculated in both
    losses, generating network transfer entropy (Net Transfer Entropy). Data analysis was
    carried out using the R Core Team software (2020)

Thesis
1
  • LEIKA IRABELE TENÓRIO DE SANTANA
  • Analysis of hydrological changes caused by human activity using the recurrence Plot

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • TATIJANA STOSIC
  • ANTONIO SAMUEL ALVES DA SILVA
  • IKARO DANIEL DE CARVALHO BARRETO
  • LIDIANE DA SILVA ARAUJO
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Feb 20, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The sustainable use of freshwater resources is a major challenge due to climate change, human practices, the construction of dams and reservoirs. The operation of a dam can be modified to produce a natural-like flow without compromising its main services. The empirical analysis of streamflow data before and after dam construction can therefore provide valuable information to the sector responsible for flow control. The objective of this workis to investigte the nature of the hydrological processes of the São Francisco River basin, and the influence of the Sobradinho dam (BA). In order to detect possible hydrological alterations caused by the construction of this dam, daily streamflow data from the São Francisco River recorded at the fluviometric stations of Juazeiro (BA) and São Francisco (MG) were analyzed for the period from 1929 to 2009. The data are provided by the National Water Agency (ANA). The Recurrence Plot (RP) method, its bivariate extension, the Cross Recurrence Plot (CRP) and its modification, the Ordinal Pattern Recurrence Graph (OPRP), as well as the Recurrence Quantification Analysis (RQA) were used to analyze the non-linear dynamics of streamflow series. The visual analysis of the RP/OPRP patterns and the corresponding set of quantitative measures obtained by the RQA indicate that the operation of the reservoir induced changes in the downstream flow (recorded at the Juazeiro station) towards a less predictable and less stable regime, while the flow dynamics upstream (at the San Francisco station) remained unchanged. The temporal evolution of RQA quatifiers (obtained by applying OPRP in sliding windows) identified the influence of the Três Marias dam on the downstream of São Francisco station. Both dams induced the same downstream flow changes, with a greater degree of change for the Juazeiro station due to the shorter distance from the upstream dam. The OPRP sliding window technique showed sensitivity regarding the dam operation and also the damping process with increasing distance between the dam and the downstream hydrological stations. For the period before construction, the RQA values decrease over time scales, showing that the complexity of the flow dynamics depends on the change in time scale. This suggests that daily flow dynamics exhibit less complexity and therefore less variability than larger-scale flows. From the analysis of the relationship between flow and precipitation, it was observed that during the natural regime, flow dynamics were more predictable than precipitation dynamics, which may be the result of the influence of other factors such as evaporation, soil moisture and vegetation cover. The CRP analysis indicated a decrease in synchronization between hydrological processes in the basin after the construction of Sobradinho. The results are expected to contribute to the literature by providing new aspects of hydrological alterations caused by human activities which can be used to improve meteorological and hydrological modeling and forecasting to help with natural disasters and water resource management.

2
  • FELIPE RICARDO SANTOS DE GUSMÃO
  • A study on the theory of parametric identifiability and its applications in new distributions and classes of probability distributions

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • FRANK SINATRA GOMES DA SILVA
  • THIAGO ALEXANDRO NASCIMENTO DE ANDRADE
  • ABRAÃO DAVID COSTA DO NASCIMENTO
  • CICERO CARLOS RAMOS DE BRITO
  • LEANDRO CHAVES REGO
  • Data: Feb 20, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Lately, many authors have proposed new classes of distributions, which are modifications of distribution functions that provide hazard functions taking various forms. Several families proposed in the literature constitute generalizations of probability distributions because, in general, the resulting distribution and the baseline have the same support. It is well known that adding parameters to distribution classes can lead to problems with identifiability and consequently bring complications to the estimation of parameters in the proposed model. This work presented definitions, which are contributions of this thesis to the theory of identifiability. As mentioned earlier, some theorems and propositions based on the aforementioned definitions have been introduced to present a new perspective on the theory. Mixtures of probability distribution functions involving addition and multiplication operations were presented and studied in terms of identifiability. The class of distributions T-G-X [Method for generating distributions and classes of probability distributions: the univariate case, Brito et al. (2019)] was displayed and discussed the identifiability of some subcases of the same. The T-G-X constitutes a multi-baseline extension, hence the bold G, of the well-known T-X class. Each G that makes up the vector of baselines G is a
    univariate probability distribution function.

3
  • JOÃO VALERIO DE SOUZA NETO
  • Topological analysis in 3D images of fish otoliths: exploring density and morphology patterns

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • ANTONIO CELSO DANTAS ANTONINO
  • ANTONIO SAMUEL ALVES DA SILVA
  • FRANCISCO MARCANTE SANTANA DA SILVA
  • PAULO JOSE DUARTE NETO
  • VIVIANE MORAES DE OLIVEIRA
  • Data: Feb 23, 2024
    Ata de defesa assinada:


  • Show Abstract
  • In this thesis, we present a comparative study of otolith density variations using Topological Data Analysis (TDA). Otoliths are calcium carbonate structures found in the inner ears of fish and are commonly used to study age and growth patterns in fish populations. Traditionally, the analysis of otolith density variations has been a computationally intensive task due to the high-dimensional nature of the data. However, TDA offers a promising approach to reduce the data dimensionality and extract meaningful topological information from otolith images. We applied the Ball Mapper algorithm to a dataset of 3D otolith images from different fish species and ages. The algorithm allowed us to constructo topological graphs representing the density variations in otoliths. We also explored the use of probabilistic sampling techniques to reduce the data and found that a sample size of 5% provided accurate representations of otolith density variations compared to the full dataset, after a Sample Topological Validation procedure developed here to ensure the efficiency and reliability of the sampling process. Topological invariants of the graphs, such as average clustering, node connectivity, assortativity, shortest path length, efficiency, and others, were used to comparizon between graphs. The comparizon of the topological properties of the full dataset with those of the 5% sample found a high degree of similarity, indicating that TDA with a reduced dataset can capture essential density information. Ball Mapper further allowed us to identify and eliminate dirt or anomalies present in otolith images, further enhancing the accuracy of our analysis. Overall, our study demonstrates the efficacy of TDA in studying otolith density variations with significant computational gains over traditional methods. The reduced data size using probabilistic sampling and the robustness of topological invariants provide valuable insights into the density patterns of otoliths. Another TDA technique, Persistent Homology (PH), was applied to the 3D image data with the expectation of unveiling a new classifier for otolith shape. PH demonstrated prominence even in a small sample by effectively separating otolith classes and revealing accurate quantitative separation results, showcasing potential use for otolith classification based on their 3D structure. Finally, a regression analysis demonstrated the possibility of estimating age, length, and radiodensity of otoliths based on the topological features resulting from the classification.

4
  • MICKAELLE MARIA DE ALMEIDA PEREIRA
  • Application of functional data analysis to CH4, CO2 and N2O emissions from different land uses

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • JANAÍNA BRAGA DO CARMO
  • JOSE ROMUALDO DE SOUSA LIMA
  • LUIZ ANTONIO MARTINELLI
  • PAULO JOSE DUARTE NETO
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • Data: Feb 26, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Inadequate management of agricultural systems, as well as changes in soil cover, are significant factors in increasing greenhouse gases (GHGs). There are statistical tools to measure the flow of GHGs, based on the temporal variation in concentration as a function of time. However, these analyzes may not cover characteristics arising from the variation and randomness present in the phenomenon. Therefore, functional data analysis (FDA) consolidates a new perspective for deriving models and optimizing techniques in exploratory data analysis, expressing notable potential in the study of variations in a given variable in relation to time, taking into account both continuous variation (linear or non-linear) and its randomness. The objective of the study is to evaluate the dynamics and complexity of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions in four types of land use (extensive pasture, intensive pasture, sugarcane row and inter-row of sugarcane) using FDA techniques from univariate and multivariate perspectives. Initially, gas flow estimates were measured using the following models: linear, exponential and functional. It can be seen that the functional model uses the gas variation itself throughout the time interval, managing to have a good representation for the flow, both for variations in the linear and non-linear structure of the gases. Then, the data were analyzed using functional statistical methods. Discrete observations were restructured as functions using B-splines smoothing. Consequently, derivatives of the functions were applied to calculate the variation in concentrations as a function of time (flows), noting great variability in land use, alternating between effluxes and inflows. Considering the gas analysis together, the first three multivariate functional principal components (MFPCA) cumulatively captured more than 90% of the total variation present in the data. Cluster analysis, referring to the scores of the main components, separated the observations into four groups. Therefore, the FDA application demonstrates that it is capable of capturing the behavior of the studied phenomenon, encompassing the continuous nature of the system. Therefore, it accurately represents the process of gas exchange between soil and atmospheric air.

5
  • FELIPE FERNANDO ANGELO BARRETO
  • Generalized transmuted families: some information and Goodness-of-fit measures based on the Mellin transform

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • FERNANDO ARTURO PEÑA RAMIREZ
  • FRANK SINATRA GOMES DA SILVA
  • JADER DA SILVA JALE
  • JOSIMAR MENDES DE VASCONCELOS
  • RENILMA PEREIRA DA SILVA
  • Data: Feb 28, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Probability distribution models have been widely studied by researchers and scientists for describing and explaining natural phenomena. In recent years, several more flexible probability distribution models have been proposed to describe data, for example in Survival Analysis. Among the models proposed in the literature, Generalized Transmuted Families stand out as they are efficient in describing and explaining data of this nature. Despite many published works that deal with new models or classes of distributions, few are aimed at developing efficient goodness-of-fit measures. The objectives of this work are: (i) to propose a new estimation criterion and goodness-of-fit measures - considering qualitative and quantitative aspects - based on the Mellin Transform. Such goodness-of-fit measures were developed using Hotelling statistics and applied, initially, to four submodels of the Transmuted-G class: Transmuted Weibull, Transmuted Fréchet, Transmuted log-logistics and Transmuted Pareto; and, later, in two submodels of the New Transmutada-G class: New Transmutada Weibull and New Transmutada Fréchet. To verify the performance of the proposed methodology, a survival analysis database and SAR image data were used; (ii) Explore properties relating to information measurements for the New Transmuted-G class: Shannon Entropy; Fisher information and mean Gini divergence. Furthermore, divergence measures such as Kullback-Leibler divergence and Chi-Square divergence were obtained to measure the closeness between two probability distributions. The density of Nova Transmutada-G is written as a mixture between the base distribution and the exponentiated base distribution, which are called its components. Furthermore, divergence measures, such as Kullback-Leibler and Chi-Square, were obtained to measure the proximity between two probability distributions within such a class, that is, between the generator's density function and its components. It was found that the Kullback-Leibler divergence between a New Transmuted-G model and its components is free from the base distribution. Furthermore, the mean Gini difference is expressed as the sum of the mean Gini difference of its components.

6
  • FILIPE MENDONCA DE LIMA

  • Construction of air temperature and humidity monitoring station with multipoint soil moisture detection system and reverse energy

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • MOACYR CUNHA FILHO
  • LUCIAN BOGDAN BEJAN
  • LEANDRO RICARDO RODRIGUES DE LUCENA
  • VICTOR CASIMIRO PISCOYA
  • RENISSON NEPONUCENO DE ARAUJO FILHO
  • Data: Aug 19, 2024
    Ata de defesa assinada:


  • Show Abstract
  • With the decreasing in world’s arable area there is a growing demand to optimize the production process. Precision Agriculture can use low-cost stations to satisfy this demand. This work proposes the construction of a station that monitors the air temperature, the relative air humidity, and the soil moisture through 6 hygrometers and that stores the data in a microSD card. The station runs on available electricity from the grid but uses batteries and a solar panel as backup energy. The device was tested at Universidade Federal Rural de Pernambuco, campus Recife, over 8 days, with the hygrometers in pots planted with Buffelgrass (Cenchrus Ciliaris), and the data collected were compared with the data from the Aeroporto meteorological station (Recife/PE). For comparison, the non-parametric Mann-Whitney, Kruskal-Wallis, and Dunn’s ad hoc tests were used. The air temperature and humidity data had a similar behavior to the Airport station, although they had a greater range, and it was possible to detect rainy periods. Soil moisture data were collected using the 6 hygrometers in a single pot and subjected to irrigation. There was a statistical difference in the reading of the hygrometers, forming three pairs with similar readings between them. There was another test to compare the hygrometers output using an analogical tool with satisfactory results. The station operated for 20 hours without electricity from the grid, showing excellent autonomy. The data analysis of the environmental variables allowed us to define the station’s viability for different real world situations, although more research and modifications are needed to use it in these situations.

7
  • DANIEL DE SOUZA SANTOS
  • Solving Black-Scholes equations with a neural network

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • BORKO STOSIC
  • ANTONIO DE PADUA SANTOS
  • FRANCISCO DE SOUSA RAMOS
  • PAULO RENATO ALVES FIRMINO
  • Data: Aug 26, 2024
    Ata de defesa assinada:


  • Show Abstract
  • The present work deals with a new methodology for pricing European options in the Brazilian market: the resolution of the Black-Scholes Equation through a Neural Network Multi Layer Perceptron. It is a supervised learning problem in which the response of the Neural Network is given by the resolution of the Differential Equation and the circumference conditions are the prices practiced in the Brazilian derivative market. It was verified that the Neural Network can learn from the data and presented better results than the analytical solution of Black-Scholes. The learning capacity of the Neural Network was also tested in comparison with ARIMA modeling and this was more accurate for short prediction horizons, but for larger horizons the neural network showed more satisfactory results.

8
  • LUCIANO SERAFIM DE SOUZA
  • Lackadaisical Quantum Walk Analyses With Partial Phase Inversion Proposal

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • FRANKLIN DE LIMA MARQUEZINO
  • ADENILTON JOSE DA SILVA
  • JOSE FERRAZ DE MOURA NUNES FILHO
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • WILSON ROSA DE OLIVEIRA JUNIOR
  • Data: Aug 27, 2024
    Ata de defesa assinada:


  • Show Abstract
  • Quantum walks have been a theme of much interest in the field of quantum computing. Defined as a theoretical model that describes the movement of a particle in a discretized  or continuous space of time, they apply the principles of quantum mechanics and present properties with great practical potential. The development of quantum search algorithms represents the main application of quantum walks. These search algorithms based on quantum walks have shown several promising results providing efficient solutions to complex problems. However, some theoretical and practical challenges still need to be overcome. In this thesis work, we use the quantum walks defined in a discrete-time space. Initially, we apply a quantum walk on the complete graph to develop a quantum search procedure capable of finding a set of synaptic weights that train a classical artificial neural network. The quantum walk in the complete graph needs a quantum operator to perform a transformation from an n-dimensional space to a four-dimensional space, which has not yet been defined. Furthermore, as the vertices of the graph are indistinguishable, their locations are given by a mapping on an n-dimensional grid. In this way, we decided to analyze the lackadaisical quantum walk in the hypercube since it is possible to reduce it to a line walk. Based on this analysis, we propose a weight value for the self-loop, which is ideal for searching for multiple marked vertices. It was possible to achieve maximum success probabilities close to 1. The results also show that adjacent marked vertices decrease the maximum probability of success. So we propose a new approach that uses multiple self-loops at each vertex and applies the partial inversion of the target state called Multi-self-loop Lackadaisical Quantum Walk. With this new approach, we also propose two new weights and achieve maximum success probabilities close to 1, even in cases where there are adjacent marked vertices.

9
  • ELIELMA SANTANA DE JESUS
  • Spatiotemporal analysis of wind speed in Pernambuco: application of Multiscale Entropy and Clustering Methods

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • GUILHERME ROCHA MOREIRA
  • JADER DA SILVA JALE
  • JOSIMAR MENDES DE VASCONCELOS
  • CRISTIANE ROCHA ALBUQUERQUE
  • KEROLLY KEDMA FELIX DO NASCIMENTO
  • Data: Aug 30, 2024
    Ata de defesa assinada:


  • Show Abstract
  • This study investigated the potential and complexity of time series for wind speed in the period from 19 to 2097 in the Northeast region of Brazil. To understand the temporal behavior of the variable in studies, hierarchical clustering and multiscale entropy methods were used. It was observed that there were no occurrences of any of the longest months or throughout the months that were observed in the winter seasons and in the spring territory. And, in the series of better use of time or energy, for a better use, for a better time scale, that is, for a greater intensity of resources, for decision-making over time, for decision-making better quality, for better use, for decision making and direction. pursuit of sustainable development. The results also show the importance of exploratory techniques and information theory in studies of meteorological/climatological events.

10
  • RAYANE SANTOS LEITE
  • Application of GAMLSS and Machine Learning techniques in volumetric modeling of Eucalyptus spp. clones.

  • Advisor : JOSE ANTONIO ALEIXO DA SILVA
  • COMMITTEE MEMBERS :
  • JOSE ANTONIO ALEIXO DA SILVA
  • CRISTIANE ROCHA ALBUQUERQUE
  • EDCARLOS MIRANDA DE SOUZA
  • ANA PATRÍCIA BASTOS PEIXOTO
  • MARCELINO ALVES ROSA DE PASCOA
  • Data: Aug 30, 2024
    Ata de defesa assinada:


  • Show Abstract
  • This study investigates the application of advanced statistical models and Machine Learning algorithms in predicting the volume of Eucalyptus spp. in the Araripe Gypsum Hub region, Pernambuco. Generalized Additive Models for Location, Scale, and Shape (GAMLSS) were employed to model the volume of three Eucalyptus spp. clones across five different spacings, using a completely randomized design. The SHASHo model was selected as the most suitable due to its ability to handle asymmetric and dispersed data. Subsequently, a two-stage modeling approach was implemented to identify the most productive clone and spacing, utilizing the SHASH model and analysis of variance. Finally, Machine Learning algorithms, with a focus on XGBoost, were applied to predict the volume of the clones. XGBoost excelled with the best predictive performance, with Shapley value analysis identifying DBH and total height as the most influential variables. The integration of these methodologies proved effective in predicting volume and supporting the sustainable management of Eucalyptus spp. plantations, offering a robust alternative to meet the region's energy demands and reduce pressure on the Caatinga.

2023
Dissertations
1
  • VANESSA KAROLINE INACIO GOMES
  • Trend analysis of climate change indices in precipitation in the state of Pernambuco

  • Advisor : ANTONIO SAMUEL ALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANDRÉ LUIZ DE CARVALHO
  • ANTONIO SAMUEL ALVES DA SILVA
  • TATIJANA STOSIC
  • Data: Feb 27, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Many studies shown that the increase in the planet’s average temperature causes the hydrological cycle to intensify. This could cause changes in rainfall patterns, such as na increase in the frequency and intensity of extreme events resulting in severe and prolonged droughts in some locations and excessive rainfall in others, which would significantly impact the hydrological availability of a region and the quality of life of its inhabitants. Thus, it is necessary to study the variability and impacts of climate change, enabling a better understanding of the area’s climate in order to adapt and mitigate these climatic conditions. In this context, the present work aimed to analyze the trends and magnitudes of 11 extreme weather indices recommended by the Expert Team on Climate Change Detection and Indices for the state of Pernambuco. For this, 809 grid points were used, which contain information regarding daily rainfall from 1961 to 2020 and three non-parametric methods were employed: the Mann-Kendall test for trend detection, sen’s slope for estimating the magnitude of the trend, and the Mann-Whitney-Wilcoxon test to assess whether there are significant differences in the index values for each region of Pernambuco: Zona da Mata, Agreste, and Sertão. In addition, the Inverse Distance Weighting interpolator was used to perform the spatial analysis of precipitation and extreme weather indices. The results indicated na intensification of drought over much of the state, with significant reductions in total annual precipitation, consecutive wet days, and an increase in consecutive dry days. The trends show an acceleration in the desertification process in the Sertão region, which is part of the semi-arid Northeast and already suffers from scarce and poorly distributed rainfall. In relation to the Zona da Mata, the extreme rainfall indices showed significant increases, alerting us to the natural disasters that affect this region. The Agreste region showed similar results to the Zona da Mata, but with less intensity. Based on the results obtained it is possible to infer that the study area tends to become drier, with rainfall increasingly concentrated in shorter periods of time, and the dry periods interspersed between these rainfall events are becoming longer.

2
  • FERNANDO JOSÉ PESSOA DE ANDRADE
  • Development of the Gamma Diffusion Process Modified and Applications

  • Advisor : CLAUDIO TADEU CRISTINO
  • COMMITTEE MEMBERS :
  • CLAUDIO TADEU CRISTINO
  • FRANK SINATRA GOMES DA SILVA
  • CESAR AUGUSTO RODRIGUES CARTILHO
  • Data: Feb 27, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The covid-19 pandemic is the biggest health emergency since the Spanish flu at the
    beginning of the last century. The extent to which these and other diseases spread in the population is determined by the Effective Reproductive Number (Re). The objective of this research is to verify the suitability of the Modified Conditional Gamma model to describe the Re dynamics of covid-19. Therefore, it is shown that the temporal evolution of Re can be mathematically characterized as a diffusive stochastic process. The database used concerns cases of covid-19 in Brazil between the years 2020 and 2022, obtained from the Brazilian online platform OpenDataSUS, with the “Date of First Symptoms” being the primary data for all analyzes in this research. Data are treated and analyzed according to parameters indicated by the Pan American Health Organization (PAHO). When applying the model to the data, the behavior of the parameters ξ and λ is verified for different scenarios and periods. Then, the predictive ability of the model is tested using envelope plots. The indication of a good predictive capacity of the model under analysis is the central point of the research, since it provides useful information to those responsible for decision-making. Finally, some improvements are indicated in the Modified Conditional Gamma model and possibilities for research extension in partnership with health researchers.

3
  • IVANILDO BATISTA DA SILVA JÚNIOR
  • Sand-temporal variability of drought characteristics in Pernambuco

  • Advisor : ANTONIO SAMUEL ALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • JOSE RODRIGO SANTOS SILVA
  • TATIJANA STOSIC
  • Data: Feb 28, 2023


  • Show Abstract
  • This work is dedicated to investigating the characteristics of drought in the state of Pernambuco based on precipitation data from the period 1962 to 2012. Since the phenomenon of drought is recognized as offering the most dangerous natural risks, which can affect the most varied regions of the world and generate economic and social damage, the increase in the search for understanding the dynamics of droughts and the number of methods of analysis created with the objective of identifying, monitoring and quantifying them. The drought indicator recommended by the World Meteorological Organization (WMO), however, is the Standardized Precipitation Index (SPI), the method adopted here. Since the SPI is an index capable not only of identifying whether there has been a drought, but also of classifying its category (mild, moderate, severe and extreme), it has been widely used in the study of this very important phenomenon. Based on data from 133 rainfall stations spread across the entire territorial extension of the state, the SPI was calculated here on an annual (SPI-12) and seasonal (SPI-3) scale. From the series obtained, the drought characteristics were investigated: frequency, affected area and intensity. Together with the results obtained for drought characteristics, the spatial interpolation method Inverse Distance Weighting (IDW) was used. In addition, based on the results of the spatial distributions obtained, the Wilcoxon-Mann-Whitney test was applied in order to identify statistical differences between the Sertão, Agreste and Zona da Mata regions of Pernambuco regarding drought characteristics (frequency, intensity and affected area). For the temporal analysis, the non-parametric Mann-Kendall tests were used to identify the trend, and the Sen's slope test for the magnitude of the trend. Results obtained for the spatial distribution of the frequency of drought on an annual scale indicated that the drought and the mild type was the one that occurred with greater frequency, mainly in the Sertão region, where it was also verified that there was a greater proportion of stations with a significant trend. On a seasonal scale, the winter and spring seasons showed more pronounced concentrations between types of drought and greater statistical differences between regions. With regard to the results of the area affected by drought, it was observed that, both in the annual scale and for the seasonal scale, the Mann-Kendall test points to the presence of a significant positive trend. As for the intensity of annual drought, the spatial distributions showed higher concentrations in the south of the Zona da Mata for general (total) and moderate droughts, and in the east of the Sertão and southwest of the Agreste for severe and extreme droughts; on the seasonal scale, there was a lower intensity of severe and extreme drought in the Sertão during winter and spring. The average intensity of drought in both scales showed a significant positive trend. Finally, the relationship between the average intensity and the area affected by the drought was obtained, which was positive for all types of droughts and in the two scales considered.

4
  • JAÍNE DE MOURA CARVALHO
  • Slashed Lomax Distribution: Goodness-of-fit measures through the Mellin transform

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • FRANK SINATRA GOMES DA SILVA
  • JHONNATA BEZERRA DE CARVALHO
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Feb 28, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Recently, various probability distributions have been proposed to achieve satisfactory results, specifically models with increased flexibility that can model data on the duration of components or the lifetime of individuals. Among these, the Slashed class models, particularly the Slashed Lomax distribution, have gained attention. This asymmetric model is defined for positive real values, and is notable for its stochastic representation and ability to fit heavy-tailed data sets. Despite the increasing number of new probabilistic models that cater to specific samples, there have been few statistical tools introduced to evaluate their goodness of fit. To address this deficit, we employed the methodology outlined in Nicolas (2002) and utilized second-type statistics (log-cumulative) derived from the Mellin Transform (TM) to provide new measures of goodness of fit for the Slashed Lomax distribution. These measures consider both qualitative and quantitative aspects. We derived the TM expression for the Slashed Lomax distribution, calculated the log-cumulants (LCs) and created the LC diagram (k ̃_3,k ̃_2). Then, we proposed a test statistic using a combination of Hotelling's T^2 statistic and the multivariate Delta method to test hypotheses about the LCs. Finally, we applied the proposed methodology to two real databases in the context of survival analysis to show its effectiveness in evaluating the fit criteria. We conducted bootstrap experiments to assess the power of the proposed test and to evaluate the performance of the estimators using the log-cumulative method (MLC), method of moments (MM), and maximum likelihood method (ML). The results revealed that the adjustment tools performed well, and that the MLC proved to be an effective estimation criterion.

5
  • GLEYCE ALVES PEREIRA DA SILVA
  • Discrete diffusion process over state graph as a model of disease spread dynamics in a population: the COVID-19 case

  • Advisor : CLAUDIO TADEU CRISTINO
  • COMMITTEE MEMBERS :
  • CLAUDIO TADEU CRISTINO
  • ANTONIO SAMUEL ALVES DA SILVA
  • SILVANA BOCANEGRA
  • Data: Feb 28, 2023


  • Show Abstract
  • Given the uncertainty in which real systems operate, especially when it involves, by its nature, unpredictable human actions or machine malfunctions. It becomes necessary to search for determinı́stic models, which contribute to the understanding of the dynamic behavior of a system, at the basic level. Such systems can be described by probabilı́stic models, taking advantage of certain features of regularity that they exhibit. Thus, one can resort to Stochastic Processes as a way to treat these phenomena quantitatively, depending on certain characteristics one can resort to Markov Processes. Given a dynamical system, whose dynamics can be given in continuous or discrete time, a study of its evolution of states over time is necessary. In some applications, the distinction between continuous and discrete systems is not critical, and the choice is made for convenience. This work seeks the description of an algorithm that is able to discretize the system studied, in a natural way, thus forming a connected graph, in order to study the dynamics of states of this same graph over time. Thus, given the input, it can generate the appropriate output, thus answering the questions pertinent to the system.

6
  • MARIA CATARINA CAVALCANTI CABRAL
  • Trend analysis in time series of wind speed in Ouricuri, Pernambuco, Brazil

  • Advisor : ANTONIO SAMUEL ALVES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • MARIA ADELIA BORSTELMANN DE OLIVEIRA
  • TATIJANA STOSIC
  • Data: Aug 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • To verify the presence of hourly, monthly, seasonal and annual wind speed trends in the period from 2011 to 2022, representative of the municipality of Ouricuri, where the Automatic Meteorological Station EMA Ouricuri (A366) is located, we applied the non-parametric statistical tests of Modified Mann-Kendall MMK associated with the Sen's Slope estimator, The choice of Station A366 was due to its proximity to the site planned for the installation of the D. João Wind Farm, which is in the initial phase of Environmental Licensing by Ibama. In Brazil, the share of renewable sources in electricity generation currently corresponds to 87.9% of the electricity matrix, with a 12.9% growth in wind power generation (EPE, 2023). The results of this study indicate that the wind speed of the EMA Ouricuri A366, located in the Sertão do Araripe Region, municipality of Ouricuri, Pernambuco, Brazil, presented hourly, monthly, seasonal and annual averages close to each other (respectively 2.98 m/h). s; 2.97 m/s; 2.96 m/s and 2.99 m/s), with very dispersed values (variability of above 30%), and, falling into the Light and Gentle Breeze category of the Beaufort table , and predominance of a negative trend in the values of the hourly, monthly and seasonal averages of the studied series.

7
  • MARCKIS LYANDRO FARIAS DE LIMA
  • Weight estimation methods in mares in the final third of pregnancy

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • ANDRESSA NATHALIE NUNES MAGALHÃES
  • ANTONIO SAMUEL ALVES DA SILVA
  • GUILHERME ROCHA MOREIRA
  • Data: Oct 9, 2023
    Ata de defesa assinada:


  • Show Abstract
  • This study aims to evaluate the use of weighing tape in pregnant mares as well as to determine the most appropriate equation for estimating the body weight of pregnant mares. Since equine scales are not readily available due to their high cost, measuring tapes are the most common method of measuring body weight in horses. However, these measurements are not always representative of the animal's actual value, with different factors potentially affecting the tape readings. The experiment was carried out in the Equideoculture Productive Didactic Module, Campus II, Center for Agricultural Sciences of the UFPB, located in the municipality of Areia. Four pregnant mares were used, evaluated weekly during the end of pregnancy. Weighing was carried out weekly on a commercial scale, measurement with a3 weight tape for horses; in addition, the collection of biometric measurements was carried out: G1—thoracic circumference; L1—body length from shoulder to ischium; L2—length from elbow to ischium; H—height at withers and N—neck circumference. The use of a weighing tape and the calculation of metabolic weight are effective methodologies in horses. However, for pregnant mares in the final third of gestation, the results demonstrate that the alternative weighing methods differ statistically from the actual weight. It can be concluded that none of the alternative methods proved to be as efficient as the scale for measuring the weight of pregnant mares in the final third. Since Martinson et al. (2014)c the most appropriate method, compared to the other methods studied in this experiment, for pregnant mares in the final third.

Thesis
1
  • JOSAFÁ JOSÉ DO CARMO REIS JUNIOR
  • Application of geometric morphometrics to understand ecological aspects of marine fish in Southwestern Tropical Atlantic

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • ANTONIO SAMUEL ALVES DA SILVA
  • TATIJANA STOSIC
  • FRANCISCO MARCANTE SANTANA DA SILVA
  • NIDIA NOEMI FABRÉ
  • Data: Jan 16, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The organism's phenotype is the result of the interaction of a set of genetic, ecological, and environmental factors. Functional morphology investigates these phenotypic variations and geometric morphometry serves as a tool that helps in the understanding of ecological phenomena related to morphology. In this work we use geometric morphometry techniques on the marine fish body to understand ecological aspects linked to trophic ecology and habitat access at a community level. Fish were collected along the continental shelf of northeastern Brazil (4-9°S), and underwater footage was used to classify bottom habitat type into SWCR (sand with corals and rocks), Algae, and Sand. Individuals were photographed in lateral view, and shape was extracted using landmarks or contours techniques along the individuals' bodies. In total we analyzed 120 species distributed in 16 orders and 45 families of demersal fish. The relationship between body shape and trophic ecology indicated that lower trophic levels (herbivores and omnivores) are characterized by a deep body and large dorsal and anal fin bases. Top predators showed an elongated body and narrow fins. Using a multiple linear regression, we found that 46% of the variability in trophic level can be explained by morphometric variables, with increasing trophic level related to body elongation and fish size, the first time such a model has been proposed. Interestingly, intermediate trophic categories (e.g., low predators) showed morphological divergence for a given trophic level. The relationship between body shape and habitat type at first did not indicate clear patterns, when looking at the volume and morphological dispersion of the morphospace. However, when we considered the morphospace composed of the species with the highest abundances in each habitat type (All species present in the habitat, species with abundance ≥ 25% and with abundance ≥ 50%), we concluded that there is a tendency to find fish with more elongated body shape in the Sand type habitat when compared to the Algae and SWCR habitats. Overall, the 120 species are divided among 13 main fish shape groups, and body elongation rate was the main axis of variation found. The morphological characteristics found are directly related to swimming performance, where success in prey capture (e.g., top predators) and habitat access (species adapted to live in an open environment with high water flow velocity, e.g., sand habitats) are favored in species with elongated body shape. Morphological proximity had low congruence with the phylogenetic tree, indicating that our morphological approach cannot be used to observe phylogenetic proximity. Our results can be expanded to other tropical or non-tropical systems, showing that morphometric data can provide important insights into the functional characteristics of fish, especially in trophic ecology and habitat use.

2
  • HENRIQUE CORREIA TORRES SANTOS
  • Parallelization and Distribution Instrument for Sequential Simulations Computationals

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • ANTONIO RODRIGUES DE CASTRO ROMAGUERA
  • BORKO STOSIC
  • RÔMULO CÉSAR CARVALHO DE ARAÚJO
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • VICTOR WANDERLEY COSTA DE MEDEIROS
  • Data: Feb 17, 2023


  • Show Abstract
  • The need for access to computational resources grows as the increasing complexity in the development of computational algorithms becomes frequent in different sectors of the scientific community. The search for these resources has stimulated the development of several cloud platforms, which abstract the complexity of a computational infrastructure while offering its users access to the resources needed for their simulations. However, the cost of accessing these resources can limit the profile of users who can access them, setting aside various studies that could be carried out in a simpler infrastructure. Furthermore, with the complexity increase of the problems to be solved in research activities through the development of computer simulations, advanced features of parallel and distributed programming have become a requirement for these simulations to be executed promptly. The existing gap in the statistics undergraduate courses syllabus opens space for the development of a solution that allows an abstraction of the complexity of this type of programming, allowing written codes to be executed sequentially. Run in parallel with minimal tweaks to the original code. In this thesis proposal, we present the Parallel Experiment for Sequential Code (PESC), a platform for distributing simulations on computers available in a network, packaging the user code in containers that abstract all complexity required to configure an execution environment and allow any user to benefit from this existing infrastructure. With an easy-to-use web module and a client module installed on the computers that will run the simulations, it is possible to run simulations in several programming languages, scripts, and frameworks (Python, Java, C, R, PyTorch, Tensorflow, among others). The results are consolidated through the user’s page with runtime statistics and a distribution map of the simulations by the computers. We will present results obtained in simulations that required more than 1000 runs with different initial parameters and various other studies that benefited from using PESC.

3
  • FÁBIO SANDRO DOS SANTOS
  • Modeling wind speed and solar radiation in Brazil using mathematical-computational techniques

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • MANOEL HENRIQUE DA NOBREGA MARINHO
  • JADER DA SILVA JALE
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • TATIJANA STOSIC
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • Data: Feb 24, 2023
    Ata de defesa assinada:


  • Show Abstract
  • In the globalized world, there is always the need for new investments in energy sources to meet all the demands, not only industrial but also population. In a world where we already have more than 8 billion inhabitants, there is a very great demand for energy for the daily needs of the population, for example. In addition to the need for energy, one concern is rising temperatures on earth. For this reason, countries have been trying at all costs to reduce the global average temperature of the earth by 2°C. For this goal to be achieved, many countries are investing in renewable energy sources as one of the ways to contribute these reductions in greenhouse gases in the atmosphere which is one of the causes of global warming. For this reason, in November 2021, in Glasgow, Scotland, the Brazil it committed by the year 2030 to reduce its greenhouse gas emissions by around 50\%, with investments in clean and renewable energy. In Brazil, the energy sources that can contribute to the country achieving this established goal are wind and solar power. From this perspective, one of our objectives in this work was to understand and analyze the persistence and mixtures of probability destruction, through statistical, numerical, and artificial intelligence methods to estimate the potential of wind and solar power generation. For this, mixtures of probability distributions and the Multifractal Method Detrended Fluctuation Analysis-MFDFA are used in the modeling of the series. In addition, the geographic spatialization of the potential of wind velocity values was performed, and it was observed that for those velocities that are above 3.0m/s, the higher the height, the greater the occurrence of these observations of velocities above this threshold. Among the five Brazilian regions (North, Northeast, South, Southeast and Midwest), it is observed that the Northeast region has higher potential for wind power generation. The region also showed good results for the installation of solar panels. Wind and solar energy sources are important for generating clean and renewable energy across the country and can be considered complementary sources. It is expected that this research will be able to assist public agencies in decision-making about investments in renewable energies, in particular, in the wind and solar energy sources. It is important to highlight that investments in wind and solar energy are needed in Brazil and around the world due to the growing need to replace conventional and non-renewable energy sources with renewable and clean alternatives.

4
  • JOSE EDUARDO SILVA
  • Geospacialization and statistical analysis of the evolution of cases of sporotricosis in Timbaúba and Grande Recife/PE - Brazil: the relationship of the disease with domestic animals

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • GUILHERME ROCHA MOREIRA
  • MOACYR CUNHA FILHO
  • NEIDE KAZUE SAKUGAWA SHINOHARA
  • RENISSON NEPONUCENO DE ARAUJO FILHO
  • VICTOR CASIMIRO PISCOYA
  • Data: Apr 14, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Sporotrichosis, a fungal disease of the genus Sporothix, present in social life, affecting human and non-human animals, characterized as an endemic disease in Latin America, eventually causing regional outbreaks in the country. Responsible for causing various injuries to tissues, being a disease with infectious potential and transmissibility. Incisive presence in felines, whose contamination occurs by traumatic inoculation via scratches, plant thorns and fights between animals, contact with contaminated soil and animal bites, thus considered an occupational disease. In the process of treatment and care, the veterinarian assumes a relevant role, from the accurate diagnosis to the appropriate care and treatment, aiming to avoid abandonment and thus contributing to minimize transmission to humans. The treatment of sporotrichosis has been carried out with the use of the drug itraconazole, in some cases associated with other drugs such as iodine, with an average duration of six months of treatment until the disease remission, the difficulty of which lies not only in the oral administration of the drug, need to isolate the animal and lack of knowledge about the disease and care on the part of guardians. The research was submitted to the Research Ethics Committee - CEP, approved by the opinion consubstantiated under the registration CAAE: 44330921.2.0000.9547 and carried out in Greater Recife, in the municipalities of Recife, Cabo de Santo Agostinho and Camaragibe, in addition to the municipality of Timbaúba, State from Pernambuco. In methodological principle, it was decided to divide the study into three chapters: I - Survey of Geospatialization and Statistics of Sporothrix spp in Academic Digital Platforms in Brazil. Aiming to reflect on postgraduate research in public and private Brazilian universities. Using the State of the Art and bibliographic methodologies, considering the time frame 2011 to 2020, in the databases, CAPES and BDBTD platforms. Whose data analysis made use of statistical analysis through ANOVA and geospatialization with the QGIS software, version QGIS-OSGeo4W-3.24.0-2 (18.02.2022). Resulting in the recovery of 49 scientific productions, 18 from the CAPES platform and 31 from the BDBTD platform. Concluding that there are records that the disease has been present in the country since 1980, as well as the treatment of the disease caused by the pathogenic agent is possible and depends on the therapy. II - Geospatialization of Feline Sporotrichosis, from the Evidence-Based Health Perspective, in the Metropolitan Mesoregion of Recife in Pernambuco/Brazil. It aimed to verify the behavior of cases of feline sporotrichosis, registered at the Veterinary Clinic in the municipality of Abreu e Lima, Pernambuco/Brazil, striving to find clinical evidence in the use of combined drugs or substitutes for itraconazole. The method used was the PICO strategy from the perspective of evidence-based health. As a result, feline sporotrichosis tends to increase in the number of confirmed cases, coexisting with various forms of treatment. Concluding that the diagnosis prevails in male felines, whose treatment and therapeutic care for healing depends on the animal's organism to the therapeutic response. III - Geospatialization and Statistical Analysis of the Evolution of Sporotrichosis Cases in Timbaúba and Greater Recife/PE - Brazil: The Relation of the Disease with Domestic Animals. The objective was to propose a management model based on geospatialization, with statistical methods applied to preventive and corrective care in order to control the evolution of cases of sporotrichosis in care at animal health establishments in Greater Recife-PE. QGIS software was used as a methodology for special analysis, specifically MMQGIS for geocoding. The addresses being converted into geographic coordinates using the Google Maps® algorithm and support of the SIRGAS 2000 UTM coordinate systems. As well as the GeoDa software (version 1.2) was used. The statistical analysis was descriptive, given the proposed variables in absolute and relative (categorical) frequencies, seeking to present the data of summary measures in: mean, median, minimum, maximum and standard deviation (numerical). The respective analyzes were performed after tabulating the data, in spreadsheets (Excel), in Jamovi Software (version 2.3), with R Core Team language (version 4.1), in R Studio Software (4.2.2) and GeoDa Software (version 1.2) , with a time frame from 2011 to 2020. Resulting in the lack of records at three collection points, which may characterize the underreporting of cases of sporotrichosis. Concluding that the lack of adequate records, registration information, animal care, at the collection points, combined with the conclusive completion of the medical record, define the evidence of underreporting of zoonosis. The diagnosis of sporotrichosis prevails in felines, males and adults, whose form of treatment follows the standard other (itraconazole). With the implementation of the Veterinary Registration System, it is possible to manage information consistent with the identification of focus areas, possible outbreaks, socio-environmental conditions, as well as making it possible to build a database with mapping of areas that aim at efficient public policies on the part of of human and non-human health services.

5
  • GUTENBERG FERREIRA DA SILVA
  • The intra-annual variability of wind speed complexity

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • IKARO DANIEL DE CARVALHO BARRETO
  • LUCIAN BOGDAN BEJAN
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • TATIJANA STOSIC
  • Data: Jun 5, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Among renewable energy sources, Wind energy is one of the fastest growing in recent decades due to its high efficiency and low pollution. As a producer of wind energy, Brazil ranks sixth in the world, behind China, USA, Germany, India and France. The assessment of wind potential at a given location requires a detailed statistical analysis of wind speed and its frequency distribution at different times and different periods of the year. However, due to the intermittency and high space-time variability of wind speed, the large-scale integration of wind energy in to the electrical grid is still a challenging task. The knowledge of the temporal organization (complexity) of wind speed can provide information about underlying stochastic processes that can be used for planning wind energy production and for developing and evaluating predictive models of wind speed and wind potential. In this work, the intra-annual temporal variability of the wind speed complexity at 50 m height in Petrolina was analyzed, by using the methods Sample Entropy (SampEn), Multiscale entropy (MSE) and Lacunarity. The Sample Entropy method evaluates the regularity of the time series, the Multiscale entropy method was developed as the generalization of Sample Entropy to analyze the complexity of non-stationary time series considering multiple time scales, and the Lacunarity method evaluates the distribution of gaps in a set of data. The Sample Entropy results showed that the period between 10h and 12h is more favorable for wind energy generation: in this period the wind speed values are higher (indicating higher wind potential) and SampEn values are lower (indicating more regular dynamics). Multiscale entropy analysis showed that for a 10-minute frequency wind speed and entropy are positively correlated, while for a 1-hour frequency a positive correlation is observed between August and December. Lacunarity analysis results showed that September is the month with the most favorable conditions for wind power generation indicated by the highest average speed and lowest lacunarity.

6
  • ADEMIR BATISTA DOS SANTOS NETO
  • Ensemble of Time Series Forecasting  Models through Copula Functions

  • Advisor : TIAGO ALESSANDRO ESPINOLA FERREIRA
  • COMMITTEE MEMBERS :
  • FRANCISCO DE SOUSA RAMOS
  • JADER DA SILVA JALE
  • PAULO RENATO ALVES FIRMINO
  • PAULO SALGADO GOMES DE MATTOS NETO
  • TIAGO ALESSANDRO ESPINOLA FERREIRA
  • Data: Jun 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The financial market is a highly dynamic environment, characterized by significant volatility in the data associated with its processes. Consequently, modeling and predicting time series derived from these markets pose substantial challenges. However, comprehending the behavior of financial time series plays a pivotal role in making more informed decisions in the business domain. Consequently, numerous studies aim to develop sophisticated methodologies for forecasting series, with a particular emphasis on financial time series prediction. Notably, studies that employ multiple models to perform forecasts have garnered attention. The combination of time series forecasting models has consistently yielded more accurate results than individual models, as demonstrated by several works in the literature. As a result, numerous techniques promoting the combination of forecasting models have been introduced since the previous century. Research efforts have focused on devising accurate combination models that effectively weight all the involved models. In this study, our objective is to showcase the potential of utilizing copula functions to combine deep learning techniques for predicting financial time series. Specifically, we employ established individual forecasting models, such as ARIMA, Artificial Neural Networks (ANN), and recurrent deep learning networks (Long Short Term Memory - LSTM), to predict five financial time series. Performance metrics, including Rooted Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), and Prediction of Change in Direction (POCID), are used to compare the results. The ensemble techniques employed in this article include simple mean, simple median, copula functions, and MLPs. The findings of this study demonstrate that combining copula functions with deep learning approaches yields superior results compared to other approaches documented in the literature. Overall, we conclude that, in the context of financial time series, combining deep learning techniques using copula functions generally leads to more accurate predictions in terms of accuracy.

7
  • BÁRBARA BEZERRA DE CARVALHO MENDES
  • Study of Species Diversity and Persistence Through Two Models Using Computational Simulations

  • Advisor : VIVIANE MORAES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ALEXANDRE DA SILVA ROSAS
  • PAULO JOSE DUARTE NETO
  • PEDRO HUGO DE FIGUEIREDO
  • TATIJANA STOSIC
  • VIVIANE MORAES DE OLIVEIRA
  • Data: Jun 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The competition theory states that, in equilibrium, the number of coexisting species competing with each other cannot exceed the number of limiting resources in an ecosystem, known as the Competitive Exclusion Principle. However, there is a biodiversity puzzle for aquatic ecosystems, where it is observed that a limited amount of resources supports the coexistence of a wide variety of phytoplankton species, known as the Plankton Paradox. Experimental results show a unimodal relationship between species diversity and resource quantity/productivity in heterogeneous environments, as well as non-equilibrium dynamics that enable the coexistence of a large number of species competing for limited resources. In the case of competition for interactively essential resources, studies have shown that competition generates fluctuations in species abundance and allows for the coexistence of many species with a lower amount of resources. Different resource limitations favor the dominance of different species, and changes in their quantities can alter species composition. One mechanism that shapes ecological and evolutionary processes observed in nature is dispersal. This concept is part of the life history of many organisms, involving the movement of offspring throughout the life cycle of virtually all plants and animals. Due to its inherent costs, dispersal has trade-offs with many life history traits. In this thesis, our objectives are to study the effects of resource quantity in an ecosystem on diversity by comparing two types of resources (essential and interactively essential) using a spatially structured computational model, and to investigate species persistence through simulations of a metapopulation model where individuals experience trade-offs between survival and dispersal. We investigate how the distribution of resources in the ecosystem, as well as the quantity available for each resource, affect the equilibrium of the ecosystem. We have observed that an increase in spatial heterogeneity leads to an increase in the number of species, reaching a peak at an intermediate level of heterogeneity, and then decreasing for higher levels of heterogeneity. We have also noticed that variations in the type of resource in competition result in variations in diversity peaks and population sizes. Depending on the scenario, specialist or generalist species may dominate. Regarding the studied metapopulation model, we highlight that the costs of dispersal influence the evolutionary outcome, which depends on the shape of the trade-off relationship. In cases of strong trade-offs, increased mortality due to dispersal leads to reduced levels of dispersal, while weak trade-offs result in higher mobility being observed. One of the main findings was the existence of a critical trade-off where the metapopulation is no longer viable, meaning it is destined for extinction.

8
  • JOSÉ DOMINGOS ALBUQUERQUE AGUIAR
  • Characterization of soil microstructure using 3d X-ray tomographic images

  • Advisor : BORKO STOSIC
  • COMMITTEE MEMBERS :
  • ANTONIO CELSO DANTAS ANTONINO
  • ANA MARIA TARQUIS ALFONSO
  • BORKO STOSIC
  • LUCIAN BOGDAN BEJAN
  • RÔMULO SIMÕES CEZAR MENEZES
  • Data: Jul 3, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Dozens of definitions of soil can be found in literature, ranging from the most straightforward concepts, where it is asserted, for example, that soil is a heterogeneous mixture of air, water, inorganic and organic solids, and microorganisms, to more complex concepts, where the soil is considered a living, four-dimensional natural Entity. However, regardless of the adopted definition, the importance of soil is unquestionable, as it provides nutrients for plant growth essential for human and animal nutrition. Moreover, history has frequently shown that its misuse can lead to poverty, hunger, drought, and ecological and economic disasters. This great importance given to soil generates a need for ongoing studies searching for methods and tools that contribute to new knowledge. A powerful tool that can observe the elements of soil in a non-destructive way is computerized tomography (CT). Despite advances in the resolution of CT equipment and computer power, there is no consensus on data analysis methods that can reveal the complexity of all elements associated with 3D soil images, especially methods that do not require a threshold to segment images. In this context, this work employs two methods originally developed for the analysis of complex signals, Detrended Fluctuation Analysis (DFA) and Fisher-Shannon (FS), to bring a new understanding of the complexity of morphological properties of soil based on the analysis of 3D CT images. Up to date, these two methods have not been used in 3D image analysis. In this work, 3D soil tomographic images were analyzed using DFA in its original form and its generalization for 2D and 3D data. The results of DFA exponents were found to be smaller than 0.5 indicating antipersistence of local density fluctuations, which are consistently stronger (lower exponent value) for the sugar cane plantation sample, than for the Atlantic Forest. Furthermore, a new complexity measure is defined as the distance from the isocomplexity line in the normalized FS plane, which may be seen as a quantifier of soil degradation level. This novel approach resulted in a high grouping success rate (91.7%) between soil covered by native vegetation (Atlantic Forest) and soil that was the subject of the degradation process as the consequence of land use change (from native Atlantic Forest to sugarcane cultivation).

9
  • ALEXANDRE HENRIQUE QUADROS GRAMOSA
  • Bayesian models for analysis of zero-inflated extreme data

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • FERNANDO FERRAZ DO NASCIMENTO
  • FIDEL ERNESTO CASTRO MORAES
  • FRANK SINATRA GOMES DA SILVA
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Aug 4, 2023
    Ata de defesa assinada:


  • Show Abstract
  • It is of fundamental importance to have knowledge of the limiting result for modeling block maxima of size n, known as the Generalized Extreme Value (GEV) distribution, which is used in modeling extreme events. However, in these extreme data, an excessive number of zeros can occur, which hinders the analysis and estimation using the GEV distribution. The Zero-Inflated Generalized Extreme Value (ZIGEV) distribution was recently created to solve this issue, with the aid of its inflator parameter ω. One of the objectives of this work is to apply this distribution to daily precipitation data, transformed into blocks of monthly maxima. In these data, there may be months without precipitation, which are computed as zero. Time series from the mesoregions of the state of Pernambuco, in the northeastern region of Brazil, were analyzed. Some of them had a predominance of non-rainy months. However, the main objective of this work is the creation of the Seasonal Zero-Inflated Generalized Extreme Value (SZIGEV) distribution, a model to analyze the seasonality of extreme data inflated with zeros. In this case, precipitation data from the cities of Recife and Petrolina in the state of Pernambuco, and from the cities of São João do Piauí and Teresina in the state of Piauí, were used. In both analyses, inferences were made under the Bayesian paradigm, with parameter estimation performed through numerical approximations of the posterior distribution using the Markov Chain Monte Carlo (MCMC) method. The results of these applications, in line with the work of Gramosa et al. (2019), reinforced that the analyses and estimations made by the ZIGEV distribution, compared to the GEV distribution, were more accurate and had a better quality of fit, highlighting the importance of using ZIGEV to model extreme data, especially when they are inflated with zeros. However, when comparing the application of ZIGEV with the SZIGEV distribution, it was noticed that due to the seasonal behavior exhibited by the data under study, the results obtained by the seasonal model (SZIGEV) were better and more precise, emphasizing the relevance of this distribution for modeling extreme data inflated with zeros and exhibiting seasonality.

10
  • MARCELO CORREIA DA SILVA
  • Development of Interactive–Responsive Systems for Data Analysis and Communication

  • Advisor : RÔMULO SIMÕES CEZAR MENEZES
  • COMMITTEE MEMBERS :
  • ALDO TORRES SALES
  • ANTONIO SAMUEL ALVES DA SILVA
  • JOSE RODRIGO SANTOS SILVA
  • MOACYR CUNHA FILHO
  • RÔMULO SIMÕES CEZAR MENEZES
  • Data: Aug 11, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The evolution of methods for data collection is undeniable, leading to a growing and accelerated availability of these in the most varied areas of knowledge. This context, the need for a proportional evolution of the tools associated with data governance is evident, since the prospecting and analysis process depends entirely on it. Therefore, considering the issue of data governance associated with communication/visualization, it is necessary to basically follow the steps of import, organization, transformation, filtering, modeling and finally presentation/communication. Evidently, in the execution of the mentioned steps, there is the application of statistical tools aiming at multiple interests and, therefore, demanding the use of computational power, both in terms of hardware and software, and in general, software for data analysis has a significant cost. In this sense, this work will demonstrate that interactive-responsive systems, focused on the data governance stages of import, transformation, filtering, modeling, and communication/visualization, when implementing relevant analysis tools and outputs, constitute efficient, easily accessible, and low cost tools for analyzing the significant data demand present in the present time. The fields of education and healthcare are among the priorities for strengthening sustainable development in Brazil and many other countries, and for this reason, they were the focus of the present thesis for the application of the developed systems. Thus, in this work, systems of diverse interests were developed to elucidate the implementation methods, each considering its own particularities. Firstly, the source code was implemented to access, process, and model the registration data for the selection process at Colégio Dom Agostinho Ikas of the Universidade Federal Rural de Pernambuco. This includes generating the ranking list in a .pdf document, as well as presenting the registration data and classification results through an interactive-responsive via the web. Additionally, the source code was developed for the analysis of Covid-19 pandemic data provided by the Ministry of Health of Brazil for the state of Pernambuco. This was motivated by the significant relevance of the topic associated with the data, as well as the opportunity to analyze the official data provided by the Brazilian Ministry of Health, regardless of their quality. In summary, the research involving the aforementioned systems are complementary in what the work proposes to demonstrate, since the first has a relative degree of sophistication in relation to data processing and treatment, while the second deals with a robust database.

11
  • CAMILA RIBEIRO DA SILVA
  • Shewhart Control Chart considering the Inflated Unit Gamma Distribution

  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • JOSIMAR MENDES DE VASCONCELOS
  • LUCIAN BOGDAN BEJAN
  • FÁBIO MARIANO BAYER
  • TATIENE CORREIA DE SOUZA
  • Data: Aug 25, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Statistical process control (SPC) is one of the axes that contemplate the area of quality control. Control charts, one of the tools of SPC, were originally developed to monitor industrial processes. However, in recent years, its application has been shown to be of great relevance in monitoring variables in different contexts. Regarding the monitoring of variables, in some cases, the objective is to monitor the behavior of variables that assume values in the intervals [0,1) or (0,1], that is, variables with inflation of zeros or ones. In view of the limitation of appropriate control charts to monitor variables in the intervals (0,1] and [0,1), the respective thesis work aims to propose control charts based on the inflated unit gamma distribution. Thus, we initially propose the unitary gamma distribution inflated at zero and one and derive its main properties.  Additionally, we derive expressions to obtain the maximum likelihood estimators of the parameters of the distribution and conduct simulations to evaluate the performance of confidence intervals and hypothesis tests in finite sample sizes. In the formulation of the model, we start from a parameterization in which the proposed distribution is expressed in terms of the mean of the inflated distribution. This parameterization becomes more attractive, considering that in control charts, when the subgroup size is greater than 1, it is common to be interested in monitoring the process mean. In addition, two applications to real data are presented to illustrate the applicability of the proposed distribution. Next, we propose the inflated unit gamma control chart, for monitoring variables that take the values zero or one. In constructing the proposed chart, we assume that the monitored variable follows inflated unit gamma distribution. An extensive Monte Carlo simulation study was conducted to evaluate the performance of the control charts in terms of run length.  We perform a comparison between the inflated unit gamma control chart and the inflated beta control chart, considering two approaches. In the first, considering individual observations and in the second, sample subgroups of size m = 8, 15, 30 and 50. Numerical results show that the proposed chart performed well in the two approaches considered. Additionally, an application to real data sets illustrates the applicability of the proposed control chart.

12
  • JOÃO SILVA ROCHA
  • Constructor methods of probabilistic distribution classes via function compositions

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • CICERO CARLOS RAMOS DE BRITO
  • JOSE ARAUJO DOS SANTOS JUNIOR
  • KLEBER NAPOLEAO NUNES DE OLIVEIRA BARROS
  • MOACYR CUNHA FILHO
  • WILSON ROSA DE OLIVEIRA JUNIOR
  • Data: Aug 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The study of the constructors of probabilistic distribution classes by composition of functions aims to present six methods that generalize and generate probability distributions from the composition of functions. The methods proposed here allow the construction of classes of distributions, using monotonic functions of predefined distributions. With these methods it is possible to find new probabilistic distributions, classes of probabilistic distributions and also families of probability distributions, including some already present in the literature. Propositions are presented for the construction of the methods of this work, after that, tables are displayed with some values and pairs of increasing and decreasing continuous functions, together with their derivatives to feed the expressions of the constructor methods, generating some subcases of these methods. Initially, it is presented in this study, the methods that generate classes of probabilistic distributions, via compositions of cumulative distribution functions – cdf, in which baseline mixtures will be used from the construction of connection functions, together with the distribution construction methods. Next, methods for generating classes of probabilistic distributions by probability density function composition – pdf, based on the construction of linkage functions with baseline mixtures are presented. Studies of the supports of the functional generators of probabilistic distributions and the identifiability of the classes generated by the proposed methods are also developed. Some applications of these methods on simulated or real data are explained. In addition, for the classes and distributions generated by the functional models of the cdf and the pdf, there is the development of the expansions of the cdf and the pdf, the risk function, expansions for moments of order m, and for the moment generating function, as well as for the characteristic function, the expansions of central moments m and for the general coefficient, for the mean deviation and quantile deviation, the derivatives of the log-likelihood function and, the entropies of Shannon and Renyi. As a result, applications of a case of the methods are developed in which they are used in simulated data and/or in real data, thus pointing out the viability and generalization that serve as an anchorage for other researches in the different branches of the agricultural sciences.

13
  • MARCELA PORTELA SANTOS DE FIGUEIREDO
  • The generalized composition that generates growth/degrowth models applied to agricultural sciences

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • CICERO CARLOS RAMOS DE BRITO
  • FRANK SINATRA GOMES DA SILVA
  • GUILHERME ROCHA MOREIRA
  • JOSIMAR MENDES DE VASCONCELOS
  • JOÃO DE ANDRADE DUTRA FILHO
  • Data: Nov 30, 2023
    Ata de defesa assinada:


  • Show Abstract
  • The objectives of this work were: To generalize the method of Santos et al (2019), adding the operation of function composition to the method and to create new models applied to agricultural science data. The first chapter is a literature review related to growth models applied to animal growth and the kinetics of gases produced by the in vitro technique. In the second chapter, the generalization of the method by Santos et al. (2019), adding the function composition operation. A new unicompartmental model was presented, created by the composition of the Brody model with that of Von Bertalanffy, which was applied to animal growth data of male chickens of the Antenas-Canada breed. The parameters were estimated using the least squares method of the R® software, using the nlsm function that uses the Levenberg-Marquardt algorithm. The proposed model was compared to the models: Logistic, Brody, Von Bertalanffy, Gompertz, Richards, through the criteria of goodness of fit Adjusted Coefficient of Determination R_(aj.)^2, Mean Square of the Residue (QMR), Information Criterion of Akaike (AIC) and Mean Absolute Deviation (DMA), Baysian Information Criterion (BIC), Adaptively Penalizing Likelihood (PAL) and Model Predictive Ability (ρ) to define the best model. The proposed model was the most adequate to fit the data of Athens Canadian Random Bred cockerels. Therefore, this work contributed, adding the composition operation. Furthermore, the model generated by this method is effective to fit data from Athens-Canada chickens. In the third chapter of the thesis, the stabilization points of the modified Logistic model (Shofiel, Pitt and Pell, 1994) were deduced and calculated and applied to the gas production of 7 experimental diets. These points were calculated for each compartment of the bicompartmental logistic model that was used to model the phenomenon. The stabilization points proved to be important to biologically interpret the studied phenomenon. The diets: semi-simplified based on a mixture of flour from cassava leaves and alfalfa hay, semi-simplified based on alfalfa hay and simplified based on a mixture of flour from cassava leaves and alfalfa hay, showed good results and are alternatives to the reference diet for feeding New Zealand rabbits.

14
  • GABRIELA ISABEL LIMOEIRO ALVES NASCIMENTO
  • Statistical and geostatistical approach to precipitation rainfall in Sertão do Pajeú, Pernambuco/Brazil

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • MAURÍCIO COSTA GOLFARD
  • LUCIAN BOGDAN BEJAN
  • MANOEL RIVELINO GOMES DE OLIVEIRA
  • MOACYR CUNHA FILHO
  • ROSANGELA ESTEVAO ALVES FALCAO
  • Data: Dec 20, 2023
    Ata de defesa assinada:


  • Show Abstract
  • Changes in the behavior of rainfall evolution affected the hydrological cycle and consequently water resources. In cases of extreme climate change, the impact is related to changes in water resources, the occurrence of more severe and frequent floods and droughts. In this sense, studying the impacts of climate change on water resources is strategic for the elaboration, implementation and strengthening of public policies involved in the management of water resources. The present research aimed to characterize the rainfall economy in Sertão do Pajeú - PE, as well as provide subsidies for public policies aimed at water scarcity through the study and analysis of space/time. To this end, information was collected from rainfall levels in the region and surrounding areas, corresponding to the period 1993 and 2022, and statistical and geostatistical methodologies were used. data were initially processed using the regression method to complement missing data. Then, a series was checked for trend, consistency and disruption of information. In all cases, the results of the tests showed that there was no statistically significant trend, the consistency of the data was validated and the ruptures identified were not significant at the 5% level. Therefore, we approached the statistical characterization of the Pajeú variation where the climatological normal was 80.62mm. Furthermore, the classification of years was carried out using the quantile technique. The results were overwhelming, showing that some years classified as Very Dry or Dry (1993, 1998, 2015 and 2016) coincided with the occurrence of ENSO events. In relation to the geostatistical analysis, adjustments were made to the spherical, exponential and gaussian models. The models were selected using the cross-validation method. All models were well adjusted, however the gaussian model showed greater goodness of fit R2 = 90.5%. Therefore, the gaussian model proved to be more suitable for adjusting the precipitation in Sertão do Pajeú. Finally, simple spatial interpolation techniques (Thiessen, Spline and IDW), the Spline method, showed better fit and accuracy in interpolation. In relation to the other techniques, kriging considering the
    parameters of the gaussian model presented better results in terms of both adjustment (R2 = 95.1%) and accuracy (lower error measurements). Thus, it is possible to conclude that the methodology used to study the average annual rainfall in the Pajeú microregion allowed satisfactory results to be obtained in the assessment of its spatial variability, being able to determine and express the spatial continuity of rainfall and support policies public issues related to water issues in the region.

2022
Dissertations
1
  • LUANY EMANUELLA ARAUJO MARCIANO
  • Growth assessment of Buffel grass submitted to different salinity levels and leaf area analysis with image processing

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • MOACYR CUNHA FILHO
  • LEANDRO RICARDO RODRIGUES DE LUCENA
  • VICTOR CASIMIRO PISCOYA
  • Data: Feb 3, 2022


  • Show Abstract
  • Among the forage plants used in semi-arid regions, Buffel grass is highlighted, which has characteristics of resistance and rapid recovery to prolonged drought, however, few studies indicate this resistance to salinity. Thus, the objective of this study was to evaluate the relationship between salt stress and the growth dynamics, green mass production and area of Buffel grass. The experiment was conducted in an entirely randomized design, with three levels of salinity of the irrigation water, and ten repetitions, totalizing 30 experimental units. Measurements of height, cutting and weighing of green mass were made in three periods, with intervals of 28 days between them, and photography of the leaves for analysis in ImageJ software in the last period. The data obtained were submitted to the Shapiro-Wilk normality test and Bartlett's homogeneity test. Kruskal-Wallis non-parametric test and Dunn post-test were applied for data that did not follow normality, and ANOVA test and Tukey post-test for those that followed normality and homogeneity. R statistical software was used to process the analyses. The results indicate that there was no significant difference in height for the treatments with or without salt, therefore, even with the addition of salt there was no interference in growth, but when compared in relation to the periods, it can be observed that the last period was different from the others, this can be explained by means of the vegetative vigor of the plant, because when it is younger it has more efficient cell multiplication, but as it suffers injuries, the vigor is diminished and growth becomes slower. Therefore, it is likely that the use of Buffel grass in semi-arid regions that have water with high salinity levels is feasible, presenting itself as an alternative forage that is productive and resistant, requiring only adequate management for greater pasture productivity.

2
  • BRUNO DE FREITAS ASSUNÇÃO
  • CORRELATIONS IN TIME SERIES OF MANGO AND GRAPE PRICES PRODUCED IN VALE DO SÃO FRANCISCO

  • Advisor : BORKO STOSIC
  • COMMITTEE MEMBERS :
  • BORKO STOSIC
  • IKARO DANIEL DE CARVALHO BARRETO
  • TATIJANA STOSIC
  • Data: Feb 22, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Agribusiness is one of the most important economic activities developed in Brazil, its share in the national GDP is 26.6%. Fruit farming also stands out in this context, in recent decades the fruit trade in Brazil has grown significantly, serving the domestic and foreign markets. Among the main fruits produced and marketed, mangoes and grapes stand out, occupying the first and third positions of the most exported fruits by Brazil, respectively. In this work, the time series of returns and weekly price volatility of two mango varieties, “Palmer” and “Tommy Atkins”, and two types of grape varieties, “Itália” and “Benitaka”, produced in the São Francisco Valley, were analyzed. , a region with relevant participation in the production and export of these fruits. The Detrended Fluctuation Analysis (DFA) and Detrended Cross Correlation Analysis (DCCA) methods were used to calculate scale exponents of long-range correlations and cross-correlations between the analyzed series. The results showed that the volatility series have stronger persistence than the return series that presented two regimes of scale invariance with anti-persistent correlations on the larger temporal scales. The cross-correlations between the series of returns also presented two scaling regimes, obtaining, for mango, exponents similar to the series of returns of the “Tommy Atkins” variety. The values of the correlation coefficient obtained by the Detrended Cross Correlation Coefficient ρ_DCCA the method showed that for the returns and volatility of the two fruits the correlations between the series are positive, increasing with time scale and are stronger for the return series.

3
  • ANDRÉA RENILDA SILVA SOARES
  • Correlations between pesticide use and health in the northeastern region of Brazil

  • Advisor : RÔMULO SIMÕES CEZAR MENEZES
  • COMMITTEE MEMBERS :
  • ANA PATRICIA SIQUEIRA TAVARES FALCÃO
  • ANTONIO SAMUEL ALVES DA SILVA
  • MOACYR CUNHA FILHO
  • RÔMULO SIMÕES CEZAR MENEZES
  • Data: Feb 23, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The objective of this paper is to analyze the dynamics of pesticide consumption in temporary and permanent crops through the correlations between pesticide use and population health in northeastern Brazil for the year 2019. The Shapiro-Wilk Method was applied for Normality Tests and Spearman Correlation for Non-Parametric Tests aiming to correlate the amount of liters of pesticides consumed and the average coefficient of acute, subacute and chronic intoxication by these products in the region. For the research, data of planted area of crops were obtained from the Municipal Agricultural Production (PAM) of the IBGE System of Automatic Recovery of the Brazilian Institute of Geography and Statistics (IBGE-SIDRA), for the year 2019. We selected 11 temporary and permanent crops of greater expression in the Northeast and calculated the consumption of pesticides by multiplying the (average amount of pesticides used per hectare of a given agricultural crop) by the planted hectares. The estimates of the amounts of pesticides used and their active ingredients were estimated for the selected agricultural crops for each state in the Northeast, as well as the total estimate for the entire Northeast region. The health indicators analyzed were acute (pesticide intoxication), subacute (fetal malformation) and chronic (childhood cancer) types of intoxication obtained from the Department of Informatics of the SUS (DATASUS) of the Ministry of Health. The Northeast region presented a high consumption of pesticides, with a consumption of active ingredients of approximately 2.456 million liters. This consumption was ruled in greater predominance by corn with 32% of cultivated areas, followed by sugar cane (21%), soy (18%), beans (17%) and manioc (6%). The numbers of poisonings of the acute, subacute and chronic type were verified, these cases being interconnected with occupational, food and environmental exposure of the population of the region. The state of Pernambuco had the highest average coefficient of acute poisonings with 8.87 for every 100,000 inhabitants. In relation to subacute and chronic intoxications, the highest average coefficients were seen in the states of Sergipe (17.13) and Alagoas (1.84), respectively. Correlating data from the use of pesticides with health data was observed to be non-significant, but based on the precautionary principle and considering p-value < 20% the variables acute intoxication and consumption of pesticides (0.152), subacute intoxication and consumption of pesticides (0.170) considering significant and from this justification, the present study becomes relevant for health surveillance actions in the Northeast region.

Thesis
1
  • FÁBIO VERÍSSIMO JAQUES DA SILVEIRA
  • New normal-based classes of probability distributions

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • ABRAÃO DAVID COSTA DO NASCIMENTO
  • MARIA DO CARMO SOARES DE LIMA
  • CICERO CARLOS RAMOS DE BRITO
  • FRANK SINATRA GOMES DA SILVA
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Jan 10, 2022
    Ata de defesa assinada:


  • Show Abstract
  • In this work we present three classes of probability distributions build upon an innovative method that considers the Lebesgue integration of a function denoted by H(t). For the three classes we set H(t) to be the standard normal cumulative distribution function, differing only in the limits of integration. The upper limit of integration of the second class is unprecedented in the statistical literature and the third class admits two different baselines, being a competing alternative to twocomponent mixture models. The classes have the advantage of demanding no extra parameters, besides those of the baseline(s), providing thereby parsimonious models. Under certain conditions, the distributions generated by the new classes are identifiable. We present some mathematical properties of the classes, like the linear representation of the probability density function, the moments and the moment generating function. Monte Carlo simulation studies are performed to investigate the behavior of the maximum likelihood estimates of the parameters for some submodels of the classes. The same submodels examined in the simulations are also used in applications to real datasets. Information criteria and formal goodness-of-fit statistics (Cramér-von Mises and Anderson-Darling) are used as criteria for model selection in comparisons considering the studied distributions emerged from the classes and some well-known distributions commonly employed in modelling similar data. The results suggest that the distributions from the proposed classes outperform the competing models

2
  • FERNANDO HENRIQUE ANTUNES DE ARAUJO
  • ANALYSIS OF AGRICULTURAL COMMODITY PRICES USING INFORMATION THEORY METHODS

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • TATIJANA STOSIC
  • JADER DA SILVA JALE
  • LUCIAN BOGDAN BEJAN
  • JOSE RODRIGO SANTOS SILVA
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • Data: Jan 19, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Agricultural commodities are considered perhaps the most important commodities, as any sharp
    rise in food prices has serious consequences for food security and well-being, especially in
    developing countries. In this paper we analyze the predictability of Brazilian agricultural
    commodity prices during the period after the 2007/2008 food crisis and we also analyze these
    prices in sliding windows in five of these commodities, observing the evolution of these prices
    over the period before, during and after 2008/2012 food crisis. We use the method based on
    the information theory Complexity / Entropy Causality Plane (CECP) which is shown successful
    in analyzing the efficiency and predictability of financial markets and Entropy-Fisher's
    Information plane (FI). By estimating information quantifiers, a permutation entropy, statistical
    complexity and Fisher information we associate each commodity with its CECP and FI position
    and compare its efficiency (predictability) using the deviation of a random process. The coffee
    market showed greater efficiency (less predictability) while the pork market showed less
    efficiency (greater predictability). When we analyzed 5 commodities between the periods (1996-
    2018), we observed a temporal evolution of the efficiency index derived from Shannon's entropy
    and Fisher's information measure, we saw that the coffee and soybean price series present high
    and stable efficiency. For the entire period analyzed, the efficiency of the sugar market shows a
    constant increase, while the efficiency of cattle and cotton, first decreases (until the crisis) and
    then increases in the post-crisis period. In the case of sugar, live cattle and cotton, it is possible
    to observe the period of the food crisis (2007-2011), while for coffee and soy these measures
    were not able to capture differences in predictability and disorder in them, which we classify as
    commodities which did not suffer distortions in their price series during this period.


3
  • JUCARLOS RUFINO DE FREITAS
  • SPACE-TEMPORAL ANALYSIS OF THE DENGUE CASES NUMBER IN PERNAMBUCO, BRAZIL

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • GUILHERME ROCHA MOREIRA
  • JOSIMAR MENDES DE VASCONCELOS
  • MANOEL RIVELINO GOMES DE OLIVEIRA
  • MOACYR CUNHA FILHO
  • RENISSON NEPONUCENO DE ARAUJO FILHO
  • Data: Feb 18, 2022
    Ata de defesa assinada:


  • Show Abstract
  • The dengue is compulsorily notifiable disease and are present on National Compulsory Notification List of Diseases, Aggravation and Public Health Events. In Brazilian Northeast, Pernambuco is the fourth state with the highest detection rate (per 100,000 inhab.) and lethality. With that, the present research aimed to analyze the number of weekly cases of dengue in the state of Pernambuco through georeferencing analysis. The research it's about epidemiological study of the ecological type, carried out with data from the Citizen Information Service and the Pernambuco Agency for Water and Climate, in the period 2000 to 2018. Used the TerraView 4.2.2 and Qgis 3.4.11 software for spatial analysis and the free software R version 3.6.1 and IBM SPSS Statistics 20, in which statistical tests were applied. To assess the correlation between the variables, the Pearson correlation coefficient was calculated and the generalized linear models were proceeded. Have been confirmed 508,948 cases of dengue in the state of Pernambuco, in the period 2000 and 2018. The spatial distribution of cases showed a high concentration in the Metropolitan Mesoregion of Recife, with greater frequency from Recife municipality. The results indicate the formation of clusters with positive spatial autocorrelation between municipalities in the Metropolitan Mesoregion of Recife. Regarding the Pearson correlation coefficient, positive correlations were observed in 75.54% of the municipalities. From the estimates of the models, it was verified that the Negative Binomial model proved to be more satisfactory to analyze the distribution of dengue cases. Therefore, the computerized processing of georeferenced data allowed the identification of municipalities with greater vulnerabilities, providing subsidies for the regulatory agencies of epidemics and endemics in the state of Pernambuco to plan their actions.

4
  • AUGUSTO CESAR FERREIRA DE MIRANDA OLIVEIRA
  • Web Data Processing System for Spatial Analysis: An Application to Neonatal Screening Data in Rio Grande do Sul
  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • EDSON HILAN GOMES DE LUCENA
  • FABIO HENRIQUE PORTELLA CORREA DE OLIVEIRA
  • GUILHERME VILAR
  • MOACYR CUNHA FILHO
  • VICTOR CASIMIRO PISCOYA
  • Data: Feb 23, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Spatial data analysis refers to the process of finding patterns, detecting anomalies or test hypotheses and theories, through the observation of phenomena associated with an area geographic or specific location. The literature in the area presents different studies. who seek to understand their phenomena through the application of techniques and methods of spatial analysis. However, these studies have several problems. one of the problems frequent is the use of only one type of analysis, be it area or punctual. One another problem encountered is that the studies do not formally describe the process of treatment and organization applied to the data. Present the organization process data in a clear and objective way can facilitate the replication of studies to other research areas. In addition, the combined use of area and point analysis adds more information and evidence to the studied phenomena. An example would be the preview from the broadest, cases by area, to the most specific, punctual location of cases. Of that In this way, this work proposes a web system for the generation, organization and processing of geographic data compatible with geographic information systems. The proposed method, enables the construction of spatial and punctual type analyses. The dice of three Newborn screening diseases in Rio Grande do Sul, Brazil, were used for validation of the proposed method and for the construction of the spatial analyses. The obtained results, showed that the generated maps can be used in public policies that impact directly on people's quality of life and health challenges. Also, the proposed method showed potential for replication in other study contexts.

5
  • EDGO JACKSON PINTO SANTIAGO
  • Stochastic modeling via copulation of determinant meteorological variables in the production and quality of 'Palmer' mango in the fruit growing region of the São Francisco River

  • Advisor : JOSE RAMON BARROS CANTALICE
  • COMMITTEE MEMBERS :
  • FRANK SINATRA GOMES DA SILVA
  • JOSE RAMON BARROS CANTALICE
  • MARIA APARECIDA DO CARMO MOUCO
  • GERTRUDES MACÁRIO DE OLIVEIRA
  • MÁRIO DE MIRANDA VILAS BOAS RAMOS LEITÃO
  • Data: Jun 29, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Semi-arid climate variability combined with ongoing climate changes affects agricultural systems in the world with impacts on crops, and crop yields and threatens global food security. The region of the valley of the sub middle of the São Francisco River has been suffering from these changes that have brought significant losses arising from the fall in the productivity of the orchards and the disqualification of fruits for commercialization, either by the increase in rainfall during the harvest of the table grape or by the harmful effect that high temperatures and low relative humidity have caused during flowering/beginning of fruiting in mango trees cv. Palmer. Therefore, as important as quantifying is predicting extreme events related to high temperature and low relative humidity in order to understand the response mechanism of natural vegetation and agricultural crops to climate change. In this context, inference and statistical analysis are common tools to estimate the risk of events of interest, and the use of copula has been a natural choice as it is flexible to build multivariate distribution and capture the structure of interdependence between the multiple variables involved. Thus, the objective of this work was to select copulas for joint analysis of temperature and relative humidity and spatialization of probabilities in the region of the sub middle valley of the São Francisco River. The study was carried out with daily data on temperature and relative air humidity obtained between 2003 and 2018 at 17 meteorological stations in the region. For each month of data, 12 probability models and 10 copula models were fitted, which presented the best performances for univariate and bivariate estimates. For most months, the Log-Logistics-Exponenced, Generalized Extreme Values distributions and the Plackett and Frank copulas were the ones that were best suited to model the temperature and relative humidity of the air in the region of the sub middle of the São Paulo River. Francis. October and November are the months in that most of the São Francisco River sub-medium valley region is subject to maximum and average temperatures, respectively, above the thresholds of 31.6°C and 26.1°C with 90% probability. October and November are also the months with the highest risk of maximum temperatures above 33°C associated with the simultaneous occurrence of minimum relative humidity below 30%. Therefore, November is the month with the highest probability of occurrence of temperature and relative humidity unsuitable for the flowering of 'Palmer' mango trees and, therefore, more favorable to the occurrence of stenospermocarpic fruits at harvest in April or May, considering the cycle of the variety.

6
  • PATRICIA DE SOUZA MEDEIROS PINA XIMENES
  • Drought Analysis in Northeast Brazil - Probability Distribution Models and Markov Chain Approach

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • FAHIM ASHKAR
  • BORKO STOSIC
  • RÔMULO SIMÕES CEZAR MENEZES
  • SILVIO FERNANDO ALVES XAVIER JUNIOR
  • TATIJANA STOSIC
  • Data: Aug 18, 2022
    Ata de defesa assinada:


  • Show Abstract
  • Brazil is one of the tropical countries most affected by drought. The Brazilian territory contains 18.26% of dry lands concentrated mainly in Northeast Brazil (NEB). Droughts have been reported in NEB since the XVI century, and several facts about their impacts were observed during this period. Some facts that could be highlighted are livestock loss, people dying of famine, and people migrating to other regions. In this scenario, this study aimed to identify drought characteristics in the NEB that could provide beneficial information for hydrology professionals to plan possible measures to minimize drought’s negative impacts. To do that, an initial study was developed to analyze the fit of 2-parameter distributions gamma (GAM), log-normal (LNORM), Weibull (WEI), generalized Pareto (GP), Gumbel (GUM) and normal (NORM) to precipitation data from 293 rainfall stations across NEB, in the period 1988 - 2017. The maximum likelihood (ML) method was used to estimate the parameters to fit the models and the choice of the model was based on a modification of the Shapiro-Wilk statistic. The results showed that the LNORM, GAM, GP and WEI models were better fitted to the data. After that, the Standardized Precipitation Index (SPI) related to the 30 years of information was used with a Markov Chain approach to characterize drought. The results showed that a station that experienced a moderate drought recovered to a non-drought condition in about 10 to 19 months. The values increase when the initial state is severe, taking a minimum of 16 to 19 months to recover. The states of Ceará, the west portion of Rio Grande do Norte, Paraíba and Pernambuco are highlighted, presenting some spots where recovery to a non-drought condition can take up to 46 months. The mean residence time commonly varies between 1.1 to 1.2 months when the region has experienced a moderate drought condition and 1.1 to 2.2 months to recover from a severe drought condition. The probability of transitions from any category to a moderate or severe drought class was smaller than a transition to a non-drought or near-normal class. When analyzing the changes to a severe condition, the probabilities increased as the drought's severity increased. The same behaviour was observed in the moderate condition, highlighting some points in the north of NEB that showed a higher probability of transition from a state of severe drought to a state of moderate drought.

7
  • DANIEL LEONARDO RAMIREZ OROZCO
  • Some Results on Stochastic Comparisons by Majorization Theory and Goodness-of-Fit Measures Based on The Mellin Transform

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • ANA CARLA PERCONTINI DA PAIXÃO
  • FRANK SINATRA GOMES DA SILVA
  • GIANNINI ITALINO ALVES VIEIRA
  • JADER DA SILVA JALE
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Nov 4, 2022


  • Show Abstract
  • In this thesis, we provide results in two fields. In the first one, the main idea is to make stochastic comparisons using the majorization theory. We investigate conditions on the parameters of the Exponentiated Generalized class with equal and different baselines. In the second one, to describe the fits of models to the data by using Goodness-of-Fit (GoF) measures, we use the Transmuted Inverse Weibull distribution and derive the Mellin Transform from that model. We estimate the parameters by Moments, Maximum Likelihood, and Log-Cumulants (LC) methods. An interesting analysis is carried out with Hotelling's T2 Statistic. In this step, we construct an LC diagram and furnish ellipses of confidence for the LCs. The applications in this part were based on lifetime datasets such as mechanical components' survival time, electrical insulator films' failure times, and censored data from times of bladder cancer patients. We present some simulation results to verify the performance of the Moments, Maximum Likelihood, and LC methods. Kolmogorov-Smirnov and Cramér-von Mises as GoF criterias are used. Monte Carlo methods such as bootstrap and Jackknife are used to estimate population characteristics. The Mellin-based GoF test's performance is compared with Anderson-Darling and Kolmogorov-Smirnov tests.

2021
Dissertations
1
  • ADRIANO LINS LIMA
  • Estudo do comportamento de genótipos de cana-de-açúcar RB cultivados em diferentes ambientes: aplicação de análise de variância e comparação de médias

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • TEREZINHA APARECIDA GUEDES
  • MOACYR CUNHA FILHO
  • NEIDE KAZUE SAKUGAWA SHINOHARA
  • Data: Feb 12, 2021


  • Show Abstract
  • Experiments are commonly conducted in plant breeding programs and in biometrics mainly for the evaluation of potential genotypes for production. The plants of the genus Saccharum (sugar cane), the basis of this study, the most versatile plant species among all domesticated ones, which may have a range of usefulness or adaptability, or after domestication and / or evolution of genetic improvement. In view of this, one of the major difficulties of sugarcane breeding programs is the selection of genotypes in all their phases. Therefore, the use of models in order to analyze prediction over acquired results and contributions to raise the prospect of identifying potentially superior genotypes is essential. The behavioral study of genotypes was conducted on experimental data in the PMGA-CECA / UFAL assays with 11 genotypes in contrast to 3 commercial standards: RB 92579, RB962962 and SP 79-1011 and 8 RB clones (clone1, clone2, clone3, clone4, clone5, clone6, clone7 and clone8) in a randomized block design with 4 repetitions in the south, north and center of the State of Alagoas. Were evaluated the technological characteristics such as Ton of cane per hectare (TCH), Total Reducing Sugars (ATR) and Ton of Total Reducing Sugars per hectare (TATRH). The analyzes were processed in three different environments and immediately after statistical techniques such as: analysis of variances, tukey test and some presupposed analyzes to compare the behavior of sugarcane genotypes in different responses to genotype x environment interactions. In addition to influencing adaptability and stability.

2
  • LUCAS SILVA DO AMARAL
  • Ajustes de modelos não lineares ao crescimento de coelhos da raça Nova Zelândia

  • Advisor : GUILHERME ROCHA MOREIRA
  • COMMITTEE MEMBERS :
  • LUIZ CARLOS MACHADO
  • ANDRÉ LUIZ PINTO DOS SANTOS
  • GUILHERME ROCHA MOREIRA
  • MOACYR CUNHA FILHO
  • Data: Feb 15, 2021


  • Show Abstract
  • The aim of this work was to evaluate the fit of nonlinear models in describing the growth of New Zealand rabbits fed different diets. The models Santos et al. (2018), Richards, Gompertz, Brody, Von Bertallanfy and Logistic, with the objective of identifying the best fit model and, later, verifying the performance of the treatments. For the experiment, rabbits weaned at 35 days of age were used, receiving different types of feed, and their weights were measured every 5 days, up to 75 days of age. The 88 animals were divided into eleven groups: Reference Diet (REF), consisting of conventional ingredients, semi-simplified diet based on Hay from the Upper Third of Cassava Rama (FTSRM) - (SSM), semi-simplified diet based on Hay Alfalfa (FAL) - (SSA), semisimplified diet based on Cassava Leaf Flour (FFM) - (SSF), simplified diet based on mixtures of FFM and FAL - (SFA), semi-simplified diet based mixture of FFM and FAL - (SSFA), semi-simplified diet based on the mixture of FTSRM and FFM - (SSMA), SSFA diet with carbohydrates and phytase enzymes - (SSFAE), SFA diet with carbohydrates and phytase enzymes - (SFAE), SSM diet with added carbohydrates and phytase enzymes - (SSME) and SSF with added carbohydrates and phytase enzymes - (SSFE). The fit quality evaluators used were: Adjusted determination coefficient (R2aj.), Mean residual square (QMR), Mean absolute deviation (DMA), Akaike information criterion (AIC) and Bayesian information criterion (BIC), being the cluster analysis performed with the aid of the Ratkowsky index to determine clusters of the models according to the average values of the evaluation criteria. After selecting the most appropriate model, the curves identity test was performed to check for a possible divergence between the diets, in order to assess their performance in the growth of rabbits. The model that showed the best fit was Santos et al. (2018), who from the cluster analysis, joined the group that presented, on average, lower values for QMR, DMA, AIC and BIC and higher values for R2aj. When comparing the growth curves at the 5% significance level, it was observed that the reference diet (REF) performed better than the others. Diets based on Cassava Leaf Flour (SSFE, SSF, SFAE and SFE) provided inferior performance mainly due to the presence of a high level of antinutritional factors that impair the digestive process. The hay-based diet of the upper third of the cassava branch (SSM) provided satisfactory performance, with relatively low cost, and could be an economically viable alternative for the breeding ofx rabbits. The use of the Santos et al. (2018), may contribute to future studies in the description of animal growth.

3
  • MARÍLIA GABRIELA FERREIRA DE MIRANDA OLIVEIRA
  • New Estimation and Goodness of Fit criteria based on the Mellin Transform for the model q-Weibull

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • ABRAÃO DAVID COSTA DO NASCIMENTO
  • FRANK SINATRA GOMES DA SILVA
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Feb 25, 2021


  • Show Abstract
  • Currently, the amount of data and information about natural phenomena has grown faster and faster due to the use of technologies. These phenomena can be described and explained through probability models. In recent years, several more flexible probability models have been proposed to describe data in Survival Analysis. Among the models proposed in the literature, the q-distributions (particularly the q-Weibull) stand out for presenting efficiency in describing and explaining data of this nature. Despite the growing number of works that deal with new models or classes of distributions, there is a gap regarding the proposal of inference methods and proposals of new methods for measuring goodness of fit. Taking the methodology proposed by Nicolas and Anfinsen (2002) that uses the Mellin Transform, we aim to propose a new estimation method independent of the likelihood function and goodness of fit measure considering qualitative and quantitative aspects. In a numerical aspect, initially a Monte Carlo simulation was carried out in order to compare the proposed estimation method with already consolidated estimation methods, based on moments (MM) and maximum likelihood (MMV), in which we observed that the MM and the proposed method obtained the best results. Finally, two databases were applied to verify the performance of the estimators in relation to the quantitative goodness of fit measure. The results suggest that the MM and the proposed method have a similar performance for the test statistic.

4
  • NATHIELLY LIMA DO REGO
  • Analysis of the length structure of the sardine-slab (Opisthonema oglinum) captured in the Santa Cruz Channel-PE from generalized additive models for location, scale and shape
  • Advisor : PAULO JOSE DUARTE NETO
  • COMMITTEE MEMBERS :
  • PAULO JOSE DUARTE NETO
  • KLEBER NAPOLEAO NUNES DE OLIVEIRA BARROS
  • FRANCISCO MARCANTE SANTANA DA SILVA
  • Data: Aug 30, 2021


  • Show Abstract
  • Manjuba (Opisthonema oglinum) is the most common sardine in Santa Cruz Channel’s
    (CSC) landings, located on the northern coast of Pernambuco state. The species is classified
    as visiting marine origin, as it spends part of its life cycle at the sea and enters estuaries
    at strategic times. The initial research’s issue focuses on speculating some hypotheses
    related to the juveniles’ over-catching from O. oglinum species, that are relevant to fisheries
    professionals on decision-making. The high exploitation of the species and its importance
    to the economy in the municipalities surrounding the CSC led us to reflect on the need
    for investigations to promote the sustainable fishing of O. oglinum and, consequently,
    expand the understanding of the species in the CSC, once the comprehension of the length
    structure in catches is valid not only to expand knowledge but also to raise hypotheses about
    the fishing pressure on the resource. The investigation was performed by estimating the
    standard length of the specimens, using generalized linear models (GLM) and generalized
    additive models for location, scale, and shape (GAMLSS). After performing the modeling,
    we observed that the models estimated via GAMLSS enabled a better fit to describe the
    standard length of O. oglinum compared to those obtained via GLM, according to the
    GAIC criterion and residue analysis. The Box Cox t Original distribution was chosen to
    adjust the response variable with the modeling of position and scale parameters. Therefore,
    we realized the existence of seasonality in the standard length of O. oglinum captured
    in the Santa Cruz Channel, with the presence of larger individuals in the rainy season,
    and greater concentration in the center-south region of the channel. On the other hand,
    the smaller sardines were concentrated near the outflow of the Botafogo River, an area
    of secondary channels with greater mangrove coverage. We have found evidence that few
    adults enter the channel and the vast majority of specimens captured in the CSC were
    young. Thus, it would be pertinent to explore specimens that have completed at least the
    sexual maturity, since the capture of young individuals can cause an imbalance in the
    sustainability of the species.

2020
Dissertations
1
  • CATIANE DA SILVA BARROS FERREIRA
  • UMA APLICAÇÃO DOS MODELOS LINEARES GENERALIZADOS NA MODELAGEM DA PRODUÇÃO LEITEIRA NO AGRESTE MERIDIONAL PERNAMBUCANO

  • Advisor : MOACYR CUNHA FILHO
  • COMMITTEE MEMBERS :
  • GUILHERME ROCHA MOREIRA
  • MOACYR CUNHA FILHO
  • VICTOR CASIMIRO PISCOYA
  • Data: Jul 3, 2020


  • Show Abstract
  • Dairy cattle farming in Agreste Meridional has great economic and social importance for the development of livestock in Pernambuco, being considered one of the most sensitive sectors as climatic instability. The objective of the work was to study how climatic conditions and other external factors influence the production of cow's milk in the municipalities that make the region of Agreste Meridional Pernambuco. Separation data was collected from 2010 to 2018, through the Agronomic Institute of Pernambuco - IPA, and annual milk production data from 2010 to 2018 on the IBGE website, as well as data from family farming adapters and cooperatives and / or associations. To better assess the relationship between the explanatory variables and the response variable, a class of Generalized Linear models is used considering the production of cow's milk as the response variable. The results found showed that in 2012, a year of extreme drought, the average milk production fell by 36% in the region. In addition, it was found that the number of specifications that meet milk and participate in family farming were responsible for 61% of the average milk production in Agreste Meridional and that 57.7% of the municipalities have cooperatives and / or associations of milk production and a higher average milk production compared to municipalities that did not have cooperatives and / or associations.

2
  • LUCIANO PEREIRA DA SILVA
  • COMPARAÇÃO ENTRE AJUSTES DE DISTRIBUIÇÃO DE PROBABILIDADES EM DADOS DE PRECIPITAÇÃO DO ESTADO DE PERNAMBUCO

  • Advisor : FRANK SINATRA GOMES DA SILVA
  • COMMITTEE MEMBERS :
  • ANTONIO SAMUEL ALVES DA SILVA
  • FRANK SINATRA GOMES DA SILVA
  • JOSIMAR MENDES DE VASCONCELOS
  • Data: Aug 12, 2020


  • Show Abstract
  • Rain is an element that causes many concerns, because its intensity and frequency of occurrence, can cause harmful effects to society, the rain of a given location can be estimated, in probabilistic terms, by theoretical distribution models adjusted to a historical series. Precipitation data from the state of Pernambuco were used, formed by 133 monthly time series distributed over the entire state during the period from 1950 to 2012. Adherences of Probability distributions were analyzed: exponential, gamma,beta, lognormal, Weibull, normal, Gumbel Marshall-Olkin, log-logistics, exponentiated log-logistics, based on the Kolmogorov-Smirnov test at the 5% significance level . The distributions with less rejection during the adherence test were Weibull, gamma and beta, october had the lowest number of distributions considered adequate to model monthly precipitation and in march more than 99% of the pluviometric stations had some adequate probabilistic distribution to model precipitation monthly. The Weibull distribution was the best suited to model monthly precipitation.

2016
Thesis
1
  • JOSÉ ALVINO DE LIMA FILHO
  • Modelagem de ecossistemas com competição por recursos em relevos correlacionados

  • Advisor : VIVIANE MORAES DE OLIVEIRA
  • COMMITTEE MEMBERS :
  • ALEXANDRE MANOEL DE MORAIS CARVALHO
  • PAULO JOSE DUARTE NETO
  • PEDRO HUGO DE FIGUEIREDO
  • TATIJANA STOSIC
  • VIVIANE MORAES DE OLIVEIRA
  • Data: Aug 19, 2016


  • Show Abstract
  • There is no doubt about the importance of experimental and computational research in biology, specifically in Ecology, given the limited knowledge about the nature. With increased computational possibilities, studies by simulations have grown considerably, despite the limitations of computational time and the complexity of nature require specific analysis. However, all contributions are important to the knowledge progress in this direction. In this thesis, computational studies on competition for resources with spatial structure were carried out, in order to observe how some aspects of spatial ecosystem structure can influence the diversity of species. The body of research was divided into two parts. At first, the environment was fragmented before the network occupation with the species, and the resources were distributed evenly across subregions, ranging heterogeneity by the number of these subregions. The type of fragmentation was promoted through a fractal structure, correlating the non-inhabitable sites by Hurst exponent, using the fractional Brownian motion (fBm), besides being considered different fragmentation percentage. In the second part of the study, the environment was not fragmented and resources were also correlated using the fBm for generating a correlated relief. In both studies, the species-area relationship was analyzed, abundance and distribution of the relationship between diversity and heterogeneity of resources. In the first study, concerning to the species-area relationship, two schemes in power law are observed, and were investigated the values of the exponents for each case. A higher diversity and higher exponents for intermediate heterogeneities were observed. In general, for large and intermediate areas, species diversity decreased with increasing Hurst exponent, fixed the percentage of fragmentation. For small areas, there wasn’t considerable variation in diversity with increased Hurst exponent and the percentage of fragmentation. Fixed the value of the Hurst exponent and heterogeneity of resources, diversity increased with increasing fragmentation. This happened more highly for extreme heterogeneities (low and high) and lower values of the Hurst exponent, less pronounced for intermediate heterogeneities. Increasing the value of the Hurst exponent, the variation in the percentage of fragmentation caused no significant difference in diversity, especially for intermediate heterogeneities. Regarding the distribution of abundance, it was observed that both the Hurst exponent, the heterogeneity and the fragmentation percentage influenced the distribution, verifying a bimodal distribution for intermediate heterogeneities. In the second study, in which the correlated resources by the Hurst exponent, were observed, for different values for the Hurst exponent, a behavior of the species-area ratio with two schemes power law. For higher values of the Hurst exponent, the diversity of species is somewhat lower. For small areas, diversity is slightly larger for small values of this exponent and for large areas the maximum diversity is given to an intermediate value of the Hurst exponent. Still, there was no major differences in the species-area relationship with the variation of the Hurst exponent. Analyzing the distribution of abundance, there was a unimodal relation to the different Hurst values, noting highest peaks for intermediate values of this exponent, although no significant differences.

2013
Dissertations
1
  • PRISCILLA SALES DOS ANJOS
  • Correlações de longo alcance em séries temporais da velocidade do vento e radiação solar em Fernando de Noronha, Brasil

  • Advisor : TATIJANA STOSIC
  • COMMITTEE MEMBERS :
  • BORKO STOSIC
  • MOACYR CUNHA FILHO
  • PEDRO HUGO DE FIGUEIREDO
  • Data: Apr 2, 2013


  • Show Abstract
  • Solar and wind energy play a strategic role in Brazil’s efforts for sustainable development. The implementation of new, more efficient technologies for solar and wind energy conversion will facilitate energy supply in remote areas, such as the Amazon region and islands, and help reduce greenhouse gas emissions to the atmosphere, by reducing the fossil fuel consumption. The high solar irradiation levels with small seasonal variation and wind regime make the coastal areas of northeastern Brazil highly valuable for alternative energy developing programs. Fernando de Noronha archipelago, located close to the Brazilian coast in the Atlantic Ocean, belongs to the state of Pernambuco, and there are preservation rules established by federal and state government with a purpose to preserve natural resources that can be achieved through sustainable development. However, the island energy supply currently comes ma inly from diesel generators, and there is a continuous effort in developing efficient technological solutions for energy supply based on wind and solar resources. The evaluation of wind power potential requires careful statistical analysis of mean wind speed and its frequency distribution. However, the biggest challenge in integrating wind power into the electric grid is its intermittency due to temporal and spatial variability of wind in large range of scales. As a natural process of turbulence wind is the most complex weather variable with specific properties as long-range spatial and temporal correlations and fractal and multifractal dynamics. In order to contribute to better understanding of wind speed and solar radiation dynamics at the location of Fernando de Noronha island, in this work we investigate long-term correlations in temporal series of these variables recorded during the period 2003-2011. We use Detrended Fluctuation Analysis (DFA) method which was designed to detect and quantify long-term correlations in non stationary temporal series. Our results show that both wind speed and solar radiation belong to the class of persistence stochastic processes characterized by long-term correlations. The value of scaling exponent is higher for wind sp eed than for solar radiation, indicating stronger persistence. We also compare temporal variation of scaling exponents for wind and solar radiation by applying DFA on three year intervals, and find that during the studied period the scaling exponent is mor e stable for solar radiation than for wind speed. The results of this work provide new information about wind speed and solar radiation dynamics at the location of Fernando de Noronha island, and should be considered in evaluation of renewable energy potential.

2011
Dissertations
1
  • JOSIMAR MENDES DE VASCONCELOS
  • Equações simultâneas no contexto clássico e bayesiano: uma abordagem à produção de soja

  • Advisor : EUFRAZIO DE SOUZA SANTOS
  • COMMITTEE MEMBERS :
  • CLAUDIO TADEU CRISTINO
  • EUFRAZIO DE SOUZA SANTOS
  • MARIA CRISTINA FALCÃO RAPOSO
  • MOACYR CUNHA FILHO
  • Data: Aug 8, 2011


  • Show Abstract
  • The last years has increased the quantity of researchers and search scientific in the plantation, production and value of the soybeans in the Brazil, in grain. In front of this, the present dissertation looks for to analyze the data and estimate models that explain, of satisfactory form, the variability observed of the quantity produced and value of the production of soya in grain in the Brazil, in the field of the study. For the development of these analyses is used the classical and Bayesian inference, in the context of simultaneous equations by the tools of indirect square minimum in two practices. In the classical inference uses the estimator of square minima in two practices. In the Bayesian inference worked the method of Mountain Carlo via Chain of Markov with the algorithms of Gibbs and Metropolis-Hastings by means of the technician of simultaneous equations. In the study, consider the variable area harvested, quantity produced, value of the production and gross inner product, in which it adjusted the model with the variable answer quantity produced and afterwards the another variable answer value of the production for finally do the corrections and obtain the final result, in the classical and Bayesian method. Through of the detours normalized, statistics of the proof-t, criteria of information Akaike and Schwarz normalized stands out the good application of the method of Mountain Carlo via Chain of Markov by the algorithm of Gibbs, also is an efficient method in the modelado and of easy implementation in the statistical softwares R & WinBUGS, as they already exist smart libraries to compile the method. Therefore, it suggests work the method of Mountain Carlo via chain of Markov through the method of Gibbs to estimate the production of soya in grain.

2006
Dissertations
1
  • ADY MARINHO BEZERRA
  • SELEÇÃO DE VARIÁVEIS SIGNIFICATIVAS EM MODELOS OTIMIZADOS DE ESTIMAÇÃO DOS PARÂMETROS DE CULTIVO DO CAMARÃO MARINHO Litopenaeus vannamei (Boone, 1931)

  • Advisor : PAULO DE PAULA MENDES
  • COMMITTEE MEMBERS :
  • CLAUDIA HELENA DEZOTTI
  • EMIKO SHINOZAKI MENDES
  • JOSE ANTONIO ALEIXO DA SILVA
  • Data: Feb 20, 2006


  • Show Abstract
  • It was objectified to correlate of the variable-response (production, productivity, final weight and tax of survival), with the water physic (temperature in the deep one, temperature in the surface and water level) and the chemical (salinity, oxygen in the deep one, oxygen in the surface, pH and transparency of the water) and the involved variable and the adopted handling (amount of ration, period of winter, period of summer, days of culture, initial density, supplying laboratory of after-larva, area of the fishery, number of cycles, initial population, aeration and days of preparation) of the culture of the marine shrimp Litopenaeus vannamei. The data base of the shrimp farm was composed for 68 comments, correspondents to the period of 2003 the 2005 Esteem the parameters of the models it was used technique of the square minimums. The election of variable was carried through using the process of Stepwise Backward, associated the Box and Cox, to minimize the sum of square errors. The adequacy of the esteem equations and the hypothesis of linearity, normality and homogeneous variance for the errors had been analyzed on the basis of the analysis of variance and in the analysis of residue. According to the results, it was possible to conclude that the water physic and chemical influenced (p<0.05) the vanableness of the variable- response

2003
Dissertations
1
  • JAIRO XAVIER DE BRITTO
  • ANÁLISE DE DADOS LONGITUDINAIS COM ENFOQUE DA INFERÊNCIA BAYESIANA

  • Advisor : EUFRAZIO DE SOUZA SANTOS
  • COMMITTEE MEMBERS :
  • MARIA CRISTINA FALCÃO RAPOSO
  • BORKO STOSIC
  • RINALDO LUIZ CARACIOLO FERREIRA
  • Data: Jul 31, 2003


  • Show Abstract
  • O objetivo desse trabalho consiste em apresentar um estudo realizado através da Inferência Bayesiana, onde o interesse do pesquisador é comparar os resultados estimados para os parâmetros populacionais em relação aos estimados pela Inferência Clássica. A Metodologia Bayesiana baseia-se nas suposições geradas que através delas são constituídas as funções de verossimilhança, que combinadas com as distribuições a priori para os parâmetros dos modelos, geram densidades a posteriori e a partir destas são determinadas as densidades marginais. Para ilustrar a metodologia Bayesiana usamos uma estrutura de dados longitudinais referente a um estudo considerado por Gelfand, Hills, Racine-Poon, and Smith (1990), concernente a 30 jovens ratos, cujos pesos foram mensurados semanalmente por cinco semanas. Como recursos computacionais, utilizamos o pacote estatístico SAS para a análise clássica, enquanto que para análise Bayesiana, usamos o Winbugs, CODA e BOA. Ao final deste trabalho, foi possível concluir que o intervalo de confiança obtido para o parâmetro beta1 pela Inferência Bayesiana apresentou uma amplitude menor que o gerado pela Inferência Clássica. 

2002
Dissertations
1
  • MOACYR CUNHA FILHO
  • Curvas de lactação e de gordura em vacas da raça Sindi no Estado da Paraíba

  • Advisor : MARIA NORMA RIBEIRO
  • COMMITTEE MEMBERS :
  • ADAUTO JOSE FERREIRA DE SOUZA
  • EDGARD CAVALCANTI PIMENTA FILHO
  • MARIA NORMA RIBEIRO
  • PAULO DE PAULA MENDES
  • Data: Oct 29, 2002


  • Show Abstract
  • O estudo sobre curvas de lactação pode contribuir para o melhor entendimento do sistema de produção, pois o conhecimento da forma da curva e suas implicações sobre a produção de leite pode auxiliar o produtor na previsão da produção de leite de suas vacas em determinado estádio de lactação e, também, na tomada de decisões quanto ao descarte ou manejo apropriado. Entretanto, estudos desta natureza com vacas da raça Sindi praticamente não existem no Brasil. Em função disto, o objetivo do presente trabalho foi estudar as curvas de lactação e de gordura de um rebanho da raça Sindi no Estado da Paraíba, avaliando a influência da estação do parto, ano e da ordem de parto sobre a forma das curvas de lactação e gordura médias de vacas da raça Sindi, usando a função Quadrática Logarítmica. Dados referentes a 1165 lactações de produção de leite e gordura de 87 vacas da raça Sindi, controladas no período de 1987 a 1997, de propriedade da fazenda Carnaúba, pertencente à AMDA (Agropecuária Manoel Dantas Ltda), situada no município de Taperoá, microrregião do Cariri Ocidental do Estado da Paraíba, foram utilizados. Os coeficientes de determinação das curvas médias de lactação e gordura foram de 35,1% e 21%, respectivamente. Observou-se efeito significativo dos fatores ambientais (ano, estação e ordem de parto) sobre todos os parâmetros da função, mostrando que existe diferença na forma das curvas e que estas devem ser apresentadas para cada efeito, separadamente. 

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