Willames de Albuquerque Soares

Determinação da Difusividade Térmica de um Solo Multicamadas Através do Algoritmo Condução-Convecção (Determination of the Thermal Diffusivity of a Multi-layered Soil Through a Conduction-Convection Algorithm)

A temperatura do solo pode interferir em diversas atividades antropicas. E de grande importância o conhecimento desse fenomeno para diversas areas, como as ciencias ambientais, a agricultura, a engenharia e a geografia fisica A difusividade termica e um dos parâmetros termodinâmicos mais relevantes do solo, tendo grande relevância na descricao deste fenomeno. Em Sao Joao, regiao Agreste do Estado de Pernambuco, O estudo teve como objetivo determina-la atraves do algoritmo da conducao-conveccao, dividindo-a em camadas distintas, sendo avaliado seu desempenho nas profundidades de 0,08; 0,20 e 0,40 m atraves de perfis de temperaturas. A metodologia se mostrou eficaz e obteve alta correspondencia estatistica, com erros quadraticos medios percentuais inferiores a 1,9%, adquirindo poucas flutuacoes em picos maximos de temperaturas diarias para a camada mais superficial. O teste de Tukey nao apresentou diferencas significativas entre os dados de campo e os valores simulados. A subdivisao do solo em camadas distintas mostrou-se necessaria para se obter uma modelagem computacional eficiente e o metodo utilizado foi considerado adequado para uso na regiao estudo e para tipo do solo apresentado. A B S T R A C T Soil temperature can interfere with various anthropogenic activities. The knowledge of this phenomenon is of great importance for several areas, such as the environmental sciences, agriculture, engineering and physical geography. Thermal diffusivity is one of the most relevant thermodynamic parameters of the soil, having great relevance in the description of this phenomenon. In Sao Joao, in the Agreste region of the State of Pernambuco, the objective of this study was to determine it through the conduction-convection algorithm, dividing it into distinct layers, and its performance at depths of 0.08; 0.20 and 0.40 m through temperature profiles. This methodology was effective and obtained a high statistical correspondence, with the average percentage of quadratic errors being lower than 1.9%, acquiring few fluctuations in maximum peaks of daily temperatures for the most superficial layer. The Tukey test did not present significant differences between the field data and the simulated values. The subdivision of the soil into distinct layers was necessary to obtain an efficient computational modeling and the method used was considered suitable for use in the study region and for the soil type presented. Key words: Thermal diffusivity soil, convection – conduction algorithm, soil temperature, computational modeling.

Estimativa do Efluxo de Dióxido de Carbono em Resquícios de Caatinga

The objective of this study was to estimate the soil CO2 efflux in a Caatinga area in the municipality of São João, Garanhuns-PE using existing equations in the literature. The 1 Professor Adjunto da Universidade de Pernambuco – Campus Benfica was@poli.br Estimativas do efluxo de Dióxido – Oliveira e Soares Revista Diálogos N.o 16 – Set./Dez. 2016 122 measurements were performed by means of moisture and temperature sensors. The data were recorded daily a central data acquisition for 158 days and two levels of soil depth. The daily average values of the soil CO2 efflux 5 cm and 10 cm in depth were 1.59 and 1.46 μmolms, respectively. Of verified models, which uses moisture to correct the estimated values presented the best estimate, achieving numbers close to that presented in the literature.

Estimativas da Difusividade Térmica e do Fluxo de Calor de um Solo no Agreste Pernambucano (Estimates of thermal diffusivity and heat flow of a soil in Agreste Pernambucano)

Conhecer as caracteristicas termicas do solo e de fundamental importância para entendimento de seus processos fisicos. Este trabalho objetivou estimar o fluxo de calor do solo atraves da lei de Fourier para o transporte de calor e a difusividade termica do solo utilizando seis metodos (fase, amplitude, logaritmo, conducao-conveccao, arco tangente e diferencas finitas) em um solo tipico. Para isto, foram medidas temperaturas nas profundidades de 0,02; 0,08; 0,10; 0,20; 0,30; 0,40; 0,50 m por meio de termopares ao longo dos primeiros dez dias do ano. A eficacia dos metodos foi comprovada atraves de simulacoes deste mesmo perfil de temperatura do solo onde os algoritmos arco tangente e conducao-conveccao apresentaram os melhores resultados e parâmetros estatisticos, enquanto o metodo das diferencas finitas destoou dos demais. Estimativas do fluxo de calor foram realizadas a partir dos dados medidos e dos estimados, correspondendo aos mesmos resultados obtidos para cada um dos metodos em particular. A B S T R A C T Knowing the thermal characteristics of the soil is of fundamental importance for understanding their physical processes. This study aimed to determine soil heat flux through the Fouriers law for the transport of heat and thermal diffusivity of the soil using six methods (phase, amplitude logarithm conduction-convection, and finite differences arctangent) in a soil wild Pernambucano. For this, temperatures were measured at depths of 0.02; 0.08; 0.10; 0.20; 0.30; 0.40; 0.50 m by means of thermocouples during the first ten days of the year. The effectiveness of the methods has been proven through the soil temperature profile simulations where the algorithms arc tangent and driving-convection showed the best results and statistical parameters, while the finite difference method disagreed when compared the other. Heat flux estimates were made from the boundary conditions of the measured data. The best results observed in the surface layers, while the estimated values did not show satisfactory results in deeper layers. Keywords : soil temperature, soil heat capacity, thermal conductivity in the soil.

Diferentes Aspectos do Uso de Modelos Computacionais Aplicados às Ciências Ambientais

The simulation is a procedure utilized in projects and evaluation of the new system, with a reconfiguration of the 1 Prof. Adjunto da Escola Politécnica de Pernambuco, Universidade de Pernambuco. Silva, Duarte, Oliveira, Holanda, Albuquerque Neto & Soares Revista Diálogos – N.° 12 – Set. / Out. 2014 316 operation de systems. Your applications have increments every areas, helping the managers in decision making in complex problems, ensuring a better understanding of processes in organizations. This article show comments about: classification of de models as deterministic and stochastic, in the estimation of future scenarios, the use of remote sensing technique and finally the modeling of systems and software, with a little emphasis the environmental sciences.

Análise Comparativa do Fluxo de Calor no Solo em Profundidade e na Superfície (Brazil Comparative Analysis of Soil Heat Flux in Depth and Surface)

O objetivo deste estudo e comparar os resultados do fluxo de calor no solo, na superficie e em profundidade, encontrados por sensores de fluxo de calor no solo e pelo metodo harmonico, em cultivo de mamoneira. No dia sem chuvas, a pouca quantidade de agua no solo diminuiu a sua difusividade termica, provocando um maior acumulo de energia no solo, e, consequentemente, a elevacao na temperatura nas camadas mais proximas a superficie. As principais diferencas entre os valores medidos e estimados aconteceram nos horarios de maior insolacao, principalmente nos dias em que o ceu estava encoberto por nuvens. A presenca da vegetacao cobrindo o solo influenciou diretamente nos valores medidos e modelados. As estimativas tanto em profundidade como para a superficie do solo se mostraram bastante satisfatorias, tanto em dias de ceu claro como para dias de ceu encoberto. A B S T R A C T The aim of this study was to compare the results of soil heat flow, in the surface and depth, found by sensors soil heat flux and by harmonic method, in castor crop . On days without rainfall, the small amounts of water in the soil decreased its thermal diffusivity, causing a higher energy accumulation in the soil and consequently an increase at a temperature on the layers nearest the surface. The main differences between the measured and estimated values occurred at times of intense sunlight, especially on days when the sky was obscured by clouds. The presence of vegetation covering the soil directly influenced the values measured and modeled. Estimates both in depth and to the soil surface proved very satisfactory, both in clear sky conditions as for overcast days. Key-Words: Harmonic Method, Soil temperature, soil heat flux plates.

Utilização do Método Inverso para a Caracterização Hidrodinâmica de um Neossolo Flúvico

The parameters of the soil-water retention curve and the hydraulic conductivity curve of the superficial layer (5-17 cm) of a Fluvent soil, with a loamy sand texture, were determined by using the inverse method. The hydraulic functions used were combined, thus forming the so-called VGBC(B) (van Genuchten-Burdine/ Brooks&Corey) and VGBC(M) (van Genuchten-Mualem /Brooks&Corey) models. On a surface plot, located in the Experimental Station of the Group of Soil Physics of DEN-UFPE, the water content data and the matric potential of the water in the soil were obtained automatically and stored in a datalogger every 30 minutes for 72 hours, at the depths of 5, 11 and 17 cm. The implementation of the inverse method was accomplished by combining the hydraulic model, which solves the equation of Richards, with the subroutine DBCONF that minimizes an objective function by using the quasi-Newton method. The parameters α and n of h(θ) and Ks, and c of K(θ) were obtained by minimizing the sum of the squares of the deviations between the measured and the calculated water content at the depth of 11 cm. The inverse method was shown to be effective in determining the parameters of h(θ) and K(θ). Both models showed the same ability to describe the experimental data.