A Probabilistic Formulation of the Diffusion Coefficient in Porous Media as Function of Porosity

We investigate the upscaling of diffusive transport parameters using a stochastic framework. At sub-REV (representative elementary volume) scale, the complexity of the pore space geometry leads to a significant scatter of the observed diffusive transport. We study a large set of volumes reconstructed from focused ion beam-scanning electron microscopy data. Each individual volume provides us sub-REV measurements on porosity and the so-called transport-ability, being a dimensionless parameter representing the ratio of diffusive flux through the porous volume to that through an empty volume. The detected scatter of the transport-ability is mathematically characterized through a probability distribution function (PDF) with a mean and variance as function of porosity, which includes implicitly the effect of pore structure differences among sub-REV volumes. We then investigate domain size effects and predict when REV scale is reached. While the scatter in porosity observations decreases linearly with increasing sample size as expected, the observed scatter in transport-ability does not converge to zero. Our results confirm that differences in pore structure impact transport parameters at all scales. Consequently, the use of PDFs to describe the relationship of effective transport coefficients to porosity is advantageous to deterministic semiempirical functions. We discuss the consequences and advocate the use of PDFs for effective parameters in both continuum equations and data interpretation of experimental or computational work. The presented statistics-based upscaling technique of sub-REV microscopy data provides a new tool in understanding, describing and predicting macroscopic transport behavior of microporous media.

Методика анализа объемных дефектов по цифровой модели рельефа поверхности

We developed a technique for revealing and analyzing volumetric surface defects based on geomorphometric modeling, in particular, an analysis of models and maps of some morphometric variables (minimum curvature, maximum curvature, mean curvature, Gaussian curvature, unsphericity, etc.), derived from digital elevation models of a surface. The technique allows one to reveal areas of individual volume defects (cracks, film delaminations, shape deviations, etc.), to determine shape and size of both the defects themselves and adjucent modified areas, as well as to study patterns of their distribution. The technique effectiveness is exempified by defects on silicon–glass and silicon–silicon wafer assemblies, as well as a cracked Ni–W film. The technique can be promising for quality control of manufacturing and diagnostics of damages of various items, in particular, microelectronic products.

Predicting Stand Volume by Number of Trees Automatically Detected in UAV Images: An Alternative Method for Forest Inventory

In this study, we estimate the forest stock volume by multiplying the number of trees detected remotely by the estimated mean individual volume of the population (individual approach). A comparison was made with the conventional inventory method (area approach), which included 100 simulations of a simple random sampling process and a Bootstrap resampling. The study area included three stands: stand 1, 16-year-old pine; stand 2, 7-year-old pine; and stand 3, 5-year-old eucalyptus. A census was carried out in each stand for the variables diameter and total height. Individual volume was estimated by a ratio estimator, and the sum of all volumes was considered as the total parametric volume. The area approach presented parametric values within the confidence interval for 91%, 94%, and 98% of the simulations for the three stands, respectively. The mean relative errors for the area approach were −3.5% for stand 1, 0.3% for stand 2, and −0.9% for stand 3. The errors in stands 1 and 3 were associated with the spatial distribution of the volume. The individual approach proved to be efficient for all stands, and their respective parametric values were within the confidence interval. The relative errors were 1% for stand 1, −0.7% for stand 2, and 1.8% for stand 3. For stand 1 and 3, this approach yielded better results than the mean values obtained by the area approach simulations (Bootstrap resampling). Future research should evaluate other remote sources of data and other forest conditions.

Effect of Feller-Buncher Model, Slope Class and Cutting Area on the Productivity and Costs of Whole Tree Harvesting in Brazilian Eucalyptus Stands

The operational productivity and costs of tree felling operations can be influenced by several factors, among which, the machine characteristics, slope class, the cutting area and the individual volume of the trees stand out. Thus, the main objective of the present study was to analyze the productivity and production cost for two feller-bunchers with different technical characteristics operating in a eucalyptus forest. The productivity was calculated from a time study and the factors analyzed were two feller-buncher models, two slope classes, and two cutting areas. The machine cost per scheduled hour was based on the methodology of the Food and Agriculture Organization of the United Nations. Analysis of the results showed that the felling and turn operational elements occupied the most time in the operational cycle of feller-bunchers. The machine cost per scheduled hour was USD 69.69 h−1 for feller-buncher 1 and USD 102.03 h−1 for feller-buncher 2. In conclusion, the distinct technical characteristics of feller-bunchers were found to influence the productivity and, consequently, the cost, of the felling operation during the harvesting of whole eucalyptus trees.

Artificial neural networks and regression analysis for volume estimation in native species

ABSTRACT Modeling is an important tool to estimate forest production in planted areas. Although this issue has been studied worldwide, knowledge regarding volume measurement in specific locations such as Northeast Brazil is still scarce. The present study aimed to evaluated the effectiveness of artificial neural networks (ANNs) and regression analysis in estimating the timber volume of homogeneous stands of Anadantera macrocarpa, Genipa americana, and Mimosa casalpinifolia, in order to better predict the growth and production of these species. Both methods were suitable for estimating the individual volume in 7-year-old stands with different spacing. The Spurr regression model showed better statistical results and dispersion of unbiased errors for Anadantera macrocarpa and Genipa americana, whereas the Shumacher-Hall model provided more accurate volume estimates for Mimosa caesalpinifolia. The ANNs calibrated with two neurons in the middle layer exhibited the best fit for all three species. As such, artificial neural networks can be recommended to estimate the individual volumes of the species analyzed in the study area.

Wood Volume of Eucalyptus Clones Established Under Different Spacings in the Brazilian Cerrado

Eucalyptus plantations are expanding in Brazil to meet growing demands for wood-based products, such as pulp, paper, and bioenergy. New clones and silvicultural adjustments are needed with the advance of eucalypts to new regions within Brazil. This study’s objective was to evaluate the effect of variable spacing on the development of six Eucalyptus clones cultivated in the Cerrado region of Brazil. These clones were evaluated in a systematic design, with 23 spacing treatments and five biological replicates. Spacing per tree ranged from 1.20 m2 to 21 m2. At two, four, and six years after planting, diameter at breast height (DBH) and height of all trees were measured to estimate wood volume. Regression models were fitted for each trait (DBH, height, and wood volume) and showed that DBH growth was positively affected by spacing, especially at four and six years after planting (R2 > 0.58). Consequently, estimates of individual volume per tree also had a positive relationship with spacing. Total stand volume, on the other hand, was higher under densest spacings. The GG100 clone outperformed all other clones, with higher stand wood volume, especially under the densest spacings. The CCL55 clone is a promising genotype, especially under dense plantations. Study Implications Short-rotation woody crops can help meet future feedstock demands. Eucalyptus species have been introduced around the world to meet global demands for fiber and energy. One of the main factors that affects the growth and management of forests is the spacing among trees. Spacing has silvicultural, technological, and economic implications, as it can interfere with growth rates, forestry practices, wood quality, and production costs. This study showed that Eucalyptus plantations with higher density of trees per hectare could lead to higher wood productivity, even in a region with 4–5 months of drought.

Tree growth and soil fertility in plantations of genetic materials of Eucalyptus spp.

Were analyzed the growth and the relationship with soil fertility of genetic materials of Eucalyptus spp. planted in a non-traditional eucalyptus forestry region in Brazil. Five genetic materials were selected, two seminal: Eucalyptus urophylla and E. pellita and three clones: GFMO27, I224, and H13, planted in experimental plots in a completely randomized design. The diameter at breast height (DBH) and total height were measured; basal area and dendrometric variables were calculated, for the ages 24, 36, 48, 60, 72, and 108 months, both statistically compared. The soil was chemically characterized at 108 months of age and correlated with dendrometric variables. The growth of clones H13, I224, and GFMO 27 were superior to the E. pellita and E. urophylla. The levels of N and MO had a significant correlation with the volume and the Al+3 showed a positive correlation with DBH. Clone H13 showed higher values than the other materials, in all variables analyzed, reaching an individual volume of 1.27 m³ at 108 months. The other genetic materials (GFMO27, I244, and E. urophylla) proved to be variable in their growth behavior at different ages, and E. pellita had lower growth. The recommended genetic materials for planting are H13 and E. urophylla.

Effects of the 27.12 MHz magnetic field emitted by short-wave equipment on spermatogenesis

Studies have shown the influence of magnetic fields on several biological systems. Some of these fields, such as shortwave (SW) magnetic fields, have been used for therapeutic purposes. However, the possible adverse effects caused by this treatment still need to be better understood. The present study aimed to ascertain whether a single daily exposure (15 min.), for 15, 30 and 60 days, to SW magnetic field (27.12 MHz) can impede spermatogenesis. Exposure to SW magnetic fields did not change the weight of body, testis, epididymis, prostate, seminal vesicle or the gonadosomatic index. The plasma testosterone levels and testicular component volumes (seminiferous tubules, lumen, lamina propria, connective tissue, blood vessels, intertubular tissue) also remained unchanged. Histopathological analysis and spermatogenesis markers showed no changes after exposure to SW magnetic fields. However, some analyses showed changes in the lamina propria, daily sperm production, individual volume and population of Leydig cells. In conclusion, exposure to SW magnetic field for up to 60 days seems to be safe for spermatogenesis, but this exposure caused minor testicular changes that need to be better understood in the long term. This is of particular interest to health professionals who handle such SW devices for long periods of time.

Fertilização em Eucalyptus dunnii Maiden no bioma Pampa - Brasil

In silviculture, mineral fertilization is necessary to supply the nutritional demand, however, the recommendation of the quantities to be applied should aim at maintaining the productive capacity of the soil. The purpose of this study is to test whether increasing the recommended fertilizer dose improves soil fertility and increases the productivity of Eucalyptus dunnii in sites in the central region of the Pampa biome, Brazil. The doses of 150 g (T0), 225 g (T1) and 450 g (T2) of N-P2O5-K2O were applied 24:00:24 per plant, after 14 months of planting. In all tested doses, the species productivity is considered satisfactory for the site. There was an improvement in soil fertility, especially in potassium contents, in addition to a higher individual volume of Eucalyptus dunnii trees after the application of the dose of 450 g plant-1 of N-P2O5-K2O, 24:00:24 in coverage (T2).

Modelos para estimativas de ataque de Sirex noctilio (Fabricius) em povoamentos de Pinus taeda L.

Uma das principais pragas dos plantios florestais de Pinus spp. é Sirex noctilio (Fabricius), conhecida popularmente como vespa-da-madeira. Este trabalho tem por objetivo desenvolver um modelo matemático para estimar o número de árvores atacadas por Sirex noctilio em povoamentos de Pinus taeda L. baseado nos métodos de monitoramento e nas características dendrométricas do reflorestamento. Selecionaram-se, para a coleta de dados, cinco áreas localizadas no município de Palmas - PR. Foram utilizadas como variáveis independentes do modelo a serem selecionadas pelo método Stepwise a amostragem sequencial, número de indivíduos da parcela, árvores-armadilha, diâmetro a altura do peito (DAP) médio, altura média, volume médio individual, volume da parcela, idade, espaçamento, sítio, área basal da parcela, área transversal média, diâmetro médio quadrático e o DAP estratificado em três classes de diâmetro. A maior influência sobre a estimativa de ataque (Y) foi exercida pelas variáveis número de árvores atacadas detectadas na amostragem sequencial (AS) (p-valor 0,001) e o número de indivíduos da parcela (n) (p-valor 0,05). O modelo mais adequado para a obtenção da variável resposta foi δ = β0 + β1AS+β2n + ε, o qual apresentou coeficiente de determinação ajustado (R²adj) de 0,965 e erro padrão de estimativa (Syx%) de 18,65% obtendo o melhor desempenho na análise gráfica dos resíduos. O modelo pode ser utilizado pelos gestores florestais como uma ferramenta na tomada de decisões quanto ao manejo do povoamento.