ABSTRACT In academia, the study of the movement of water in the ground has been widespread since the last century. The same can be determined using the Richards equation. This is a nonlinear parabolic partial differential equation that requires parameters to generate the results of the problem. Some authors have proposed equations that represent the relationship between volumetric moisture and soil water potential, such as Haverkamp and van Genuchten. As main objective of this work, the inverse modeling was implemented to obtain the Richards equation parameters, applying the Luus-Jaakola method. To verify the mathematical model, a sensitivity analysis was performed, which allowed the observation of the effect that each parameter has on the output data, implying a linear dependence. The results produced proved to be satisfactory for the problem analyzed in our research.

ABSTRACT The simulation of terrestrial ecosystem processes, using numerical biosphere-atmosphere models that can be coupled to the Atmospheric Models, assist in a better diagnosis and forecast of climate and weather. To be able to represent a particular region, biome or ecosystem, the model parameters need to be fitted for local conditions. This work aims to assess the Luus-Jaakola (LJ) method in the optimization of the parameters in a two-stream radiative transfer model applied to a vegetation canopy. Solar radiation components (incident, S ↓, and reflected, S ↑) were measured above a sugarcane crop in a Tropical region from February 17 to 24, 2006. Among the combinations of internal and external iterations evaluated for Luss-Jaakola method, 60/30 (external/internal) iterations presented more precise albedo ( α = S ↑ / S ↓ ) simulated ( r 2 = 0 . 7386 ) and, for the accuracy of the simulated α, even though the 60/40 combination had the smallest percentual error (6.40%), the 60/30 combination was 0.03% higher. The precision and accuracy of S ↑ was greater with the parameters obtained by the inverse problem with the combination of 60/30 (external/internal) iterations respectively. In general, the behavior of simulated S ↑ at the top of the canopy was underestimated compared to the observed S ↑, especially in the early morning. For the simulated α at the top of the canopy, the model’s overestimation was observed at the lowest values of albedo. When the largest albedos are observed, only at the beginning of the day the model underestimated the values. As shown by the tests result, the parameters optimized by Luus-Jaakola method have an adequate representation of the observed data.

RESUMO Diferentes tipos de modelos matemáticos têm sido usados para prever o comportamento dinâmico do novo coronavírus (COVID-19). Muitos deles envolvem a formulação e solução de problemas inversos. Esse tipo de problema geralmente considera que o modelo, o vetor de variáveis de projeto e os parâmetros do sistema são todos valores determinísticos. Nesta contribuição, uma metodologia baseada em um processo de iteração de loop duplo é considerada para avaliar a influência de incertezas durante a resolução do problema inverso, proposto para estimar os parâmetros do modelo. No loop intermo, a solução associada ao maior valor de probabilidade associada as variáveis que apresentam incerteza é determinada. Já no loop externo, os valores das variáveis determinísticas é obtida. Para essa finalidade, a Análise de Confiabilidade Inversa é considerada como ferramenta de confiabilidade e o algoritmo de Evolução Diferencial é usado como ferramenta de otimização. Para fins de ilustração, a metodologia proposta é aplicada para estimar os parâmetros do modelo SIRD (SusceptívelInfeccioso-Recuperado-Morto) associado ao comportamento dinâmico da pandemia de COVID-19, considerando dados reais da epidemia da China e incertezas no número básico de reprodução (ℛ0). Os resultados obtidos demonstram que o aumento da confiabilidade implica no aumento do valor da função objetivo.

ABSTRACT Different types of mathematical models have been used to predict the dynamic behavior of the novel coronavirus (COVID-19). Many of them involve the formulation and solution of inverse problems. This kind of problem is generally carried out by considering the model, the vector of design variables, and system parameters as deterministic values. In this contribution, a methodology based on a double loop iteration process and devoted to evaluate the influence of uncertainties on inverse problem is evaluated. The inner optimization loop is used to find the solution associated with the highest probability value, and the outer loop is the regular optimization loop used to determine the vector of design variables. For this task, we use an inverse reliability approach and Differential Evolution algorithm. For illustration purposes, the proposed methodology is applied to estimate the parameters of SIRD (Susceptible-Infectious-RecoveryDead) model associated with dynamic behavior of COVID-19 pandemic considering real data from China’s epidemic and uncertainties in the basic reproduction number (ℛ0). The obtained results demonstrate, as expected, that the increase of reliability implies the increase of the objective function value.

RESUMO O objetivo deste trabalho é realizar uma análise comparativa de alguns modelos de cálculo para consolos de concreto pré-moldado. Para isso, são analisados os modelos de cálculo das normas brasileiras (NBR 9062) e europeia (EUROCODE 2) e de um manual de projeto norte-americano (PCI). Além disso, são analisados três modelos de cálculo sugeridos na literatura. Busca-se nessa comparação identificar os modelos que melhor representam a força de ruína dos consolos, seja pelo escoamento do tirante ou pelo esmagamento do concreto da biela. Além disso, busca-se identificar a contribuição da armadura de costura na resistência do consolo. Para isso, foi montado um banco de dados a partir de resultados de ensaios de consolos de concreto realizados por diversos pesquisadores presentes na literatura, no qual os modelos em questão foram aplicados. Utilizando-se de ferramentas estatísticas, são definidos coeficientes de ajustes a serem aplicados aos modelos para uso em projeto e que levam em conta a dispersão de resultados encontrada na análise.

ABSTRACT The main objective of this paper is performing a comparative analysis of some design models for precast concrete corbels. For this, it was analyzed design models from Brazilian (NBR 9062) and European (EUROCODE 2) Codes and a US design handbook (PCI). Moreover, three analytical models showed in the literature are analyzed. The objective of this comparative is identifying the best design models to represent the failure load of concrete corbels by the tie yields or by the concrete crushing. Moreover, it is intended to evaluate the contribution of horizontal stirrups to resistance of concrete corbels. For this, a database was assembled from test results of concrete corbels carried out by several researchers and they are showed in the literature. The design models were applied to this database and from statistical tools, adjustments coefficients are recommended to be applied on these design models to take into account the results dispersion found in the analysis.

Resumo Paca (Cuniculus paca Linnaeus, 1766) é o segundo maior roedor brasileiro. A qualidade da carne e a forte tradição da caça de subsistência são fatores que contribuem significativamente para o declínio das populações. Apesar da proibição a caça no Brasil, no momento ainda não há ferramentas disponíveis para identificar a carne e seus produtos como prova forense. Neste trabalho propomos um método eficaz de identificação, baseado em polimorfismos de único nucleotídeo no gene Citocromo b, objetivando diferenciar material biológico de paca das espécies domésticas comumente utilizadas como alimento no Brasil. A identificação das amostras de paca foram possíveis em 100% das amostras analisadas.

Abstract Paca (Cuniculus paca Linnaeus, 1766) is the second largest rodent found in Brazil. The quality of the meat and a long tradition of hunting have contributed to the decline of the natural populations of this species. Hunting of paca is strictly prohibited in Brazil, but in spite of this restriction, no forensic tools are available for the identification of the meat. We describe an efficient method, based on single nucleotide polymorphisms of the cytochrome b gene, that can be used to differentiate biological material derived from paca from those of domestic species commonly used as sources of meat. The identification of the presence of C. paca in the samples was 100% reliable.

As técnicas inversas são ferramentas muito utilizadas na determinação dos parâmetros envolvidos na modelagem de processos industriais. Neste trabalho o método Random, Restricted Window (R2W) é empregado na estimação dos parâmetros de transferência de massa envolvidos na cromatografia da separação da glicose e frutose a partir do suco de caju. O R2W é um método estocástico simples, que analisa a função custo a partir de estimativas aleatórias pertencentes a um domínio definido para os parâmetros que se deseja ajustar, assumindo novas buscas aleatórias através de uma janela de domínio restrito próxima aos melhores candidatos à solução do problema de interesse. Na modelagem do processo cromatográfico foi utilizada uma nova abordagem fenomenológica, chamada de "velocidade da frente de convecção", a qual mostrou potencial na caracterização da coluna cromatográfica. Nesta, a velocidade da fase móvel (líquida) é considerada o fator dominante no transporte das moléculas ao longo da coluna. O método R2W mostrou-se eficaz na obtenção dos parâmetros do modelo fornecendo uma ótima concordância entre os resultados da simulação computacional e os dados experimentais.

Inverse techniques are tools widely used in the determination of parameters involved in the modelling of industrial processes. In the present work the method Restricted Random Window (R2W) is employed to estimate the parameters of mass transfer involved in the chromatographic separation of glucose and fructose from cashew apple juice. The R2W is a simple stochastic method, that evaluates the cost function for random estimates within the domain for the parameters to be adjusted, with new random searches performed within a restricted domain in the vicinity of the best solution candidates for the problem of interest. In the chromatographic process a new approach phenomenological is used, called "front velocity", which considers as the dominant factor in the molecules transfer in chromatographic columns the liquid phase velocity. The R2W method has shown to be effective in the model parameters determination yielding a good agreement between the computational simulation and experimental data.

An extreme conditions situation, e.g. pre-salt deep sea exploration, requires new materials with even better performance. Nanotechnology is the new paradigm that can lead to the development of these new super materials. The effect of graphene pileups dispersion into carbon fiber/epoxy composites was investigated experimentally. The dispersion process was based on sonication and high shear mixing. XRD and SEM indicate that although the dispersion process can lead to exfoliated nanostructures, there is a saturation limit for the epoxy system, around 0.5 wt. %. The addition of graphene to carbon/epoxy composites seems to have no influence into stiffness, as the slopes of the stress-strain curves were near constant for all specimen tested. The bending strength, however, was heavily influenced by formation of graphene pileups into epoxy matrix and its dispersion around the carbon fibers. The increase on bending strength from 623.01±70.16 MPa (control samples) to 1259.92±61.73 MPa for 0.5 wt. % graphene addition represents an average improvement of 102%. This can be attributed to changes on failure mechanism, moving from intra-laminar failure to a mix failure mode where inter- and intra-laminar failure are combined in a zigzag pattern. A possible explanation for such behavior is the formation of strong bonds at the fiber/matrix surroundings due to nanostructures formation.