Resumo em Inglês:

ABSTRACT This study aimed to present a solution in glued laminated timber to replace frame structures built in reinforced concrete and metallic structure, which are common in agricultural buildings in western Paraná such as those destined to laying poultry house building by agricultural cooperatives. Structural behavior of frames build from Araucaria angustifolia glued boards and vegetable oil-based polyurethane adhesive was evaluated. Tests were carried out to characterize wood and adhesive to obtain verification/sizing parameters. Initially, a full-scale structural project was conducted to meet standard laying poultry house specifications. Afterwards, five units of straight three-articulated frames on a 1:2.5 reduced scale were designed, built, and subjected to strength tests until breaking. They were built with a 2-meter free span and a 15° slope, suitable for using metal roof tiles. The average for structure ultimate strength was 4.14 times the design load. Structures had satisfactory mechanical performance and displacements lower than those recommended by NBR 7190 (1997) standard (ABNT). Therefore, building glued frames with Parana pine boards and vegetable oil-based glue is technically feasible.

Resumo em Inglês:

ABSTRACT Faced with the increasing demand for renewable energy, researchers have developed several ways to generate them, such as biogas. Thus, the present study aims to demonstrate the economic viability of electricity generation from biodigesters in a pig farm to contribute to sustainable development by reducing pollution in the environment. Studies focused on biomass derived from pig waste are still scarce. Moreover, one of the motivations of the present study is the fact that Brazil is a major producer and exporter of pig meat, with most of the production taking place in the south and southeast regions. The methodology used is defined as exploratory, descriptive, explanatory, and applied. The scientific procedures were documentary and bibliographic research, case study, and cost analysis. An economic management model was developed using financial management instruments such as cash flow, internal rate of return, and simple and discounted payback, confirming the economic viability of the investment made for generating energy from animal biomass produced in a pig farm located in the interior of Rio Grande do Sul.

Resumo em Inglês:

ABSTRACT This work aims to develop and validate a model based on chemical equilibrium to predict the composition of syngas produced by gasification of woody biomass (sawdust). The model uses Gibbs Energy minimization to evaluate the composition of the system in chemical equilibrium. The results are validated by comparison between experimental data from a gasification experiment and those of other similar models in the literature. The study shows good agreement among experimental results and elucidates the role of solid unburned carbon in such systems, which is present in considerable amount. It can be concluded that equilibrium models can be used to predict carbon conversion in gasification systems.

Resumo em Inglês:

ABSTRACT One way of making livestock farming a more sustainable practice is to raise cattle organically. However, regardless of the production system, there is a generation of residues that can be converted into energy resources using biodigesters. This study aimed to evaluate the addition of inoculum in the anaerobic biodigestion of cattle manure under organic (OPS) and conventional production systems (CPS) in an Indian model biodigester. The physicochemical (pH, EC, TS, VS, DBO, and COD) and microbiological characteristics of the affluent and effluent, as well as the production, potential, and qualitative characteristics of the biogas, were evaluated. CPS showed higher reductions in TS, VS, BOD, and COD than OPS, with the highest effect of biogas production. Regarding the effect of inoculum addition, the treatment with 20% inoculum provided in both production systems high acceleration at the starting point of biogas production and increased energy potential, as well as high reductions in VS, BOD, and COD. Thus, there is a need to use 20% inoculum for high biogas productivity, regardless of the production system.

Resumo em Inglês:

ABSTRACT The intermittence of solar radiation, due to continuous rainy or cloudy days, is a limitation of simple and small solar dryers. These conditions often make them impossible to use. By including storage systems (thermal accumulation) and/or auxiliary energy sources, drying processes or dehydration can be conducted continuously, even during periods of low insolation. Therefore, the present work simulates and evaluates the thermal and energetic behavior of a hybrid system for heating the air that is directed to the dehydration chamber of a solar food dryer. The software selected for the simulation was TRNSYS. The simulated hybrid system consists of a flat plate solar collector and an arrangement of electrical resistors that guarantee the entry of air, at a constant temperature, into the dehydration chamber. The target temperature selected is 70 oC, and the absence of food products in the chamber is assumed. An arrangement with four electric resistors totaling 1900 W, with three different powers of 1000 W, 500 W, and 200 W proved adequate to guarantee the entrance of air at a constant temperature when considering the climatic conditions of a city in the South of Brazil.

Resumo em Inglês:

ABSTRACT To improve the picking rate and reduce the wrong picking rate of the existing wolfberry harvesting machinery, in this study, the binding force and physical appearance of the immature fruit stalk, mature fruit stalk, flower, and leaf were studied to guide the designing of new-generation wolfberry harvesting machinery and lay theoretical foundation for further studies on biomechanical properties of wolfberry. By preprocessing the experimental data with the Pauta criterion, the distribution range of the binding force and physical appearance of stalk were obtained; the binding force was not influenced by the picking temperature, mass of the fruit, and location of the branch of the fruit. The length-diameter ratio of mature fruit was confirmed by image processing. The constitutive equations for immature fruit stalks and mature fruit stalks were established. The breaking strength of the mature fruit stalk was obviously higher than that of the immature fruit stalk; moreover, the breaking strength of the mature and immature fruit stalk of the four wolfberry varieties differed obviously. The experimental results obtained in this study can provide detailed data for the parameter design of a new-generation wolfberry harvesting machinery.

Resumo em Inglês:

ABSTRACT The objective of this work was to study the influence of two postharvest processing methods on the biochemical composition and sensory analysis of a Colombian specialty coffee. For this purpose, coffee beans (Coffea arabica) of the Castillo variety were collected and processed using the wet and semi-dry methods, and the drying process was conducted in a sun drier prototype with a plastic parabolic cover, with a maximum drying air temperature of 50 °C; green coffee beans were managed according to the official Specialty Coffee Association cupping protocol and roasted to a medium and dark degree. Physicochemical determinations (pH, color, titratable acidity, caffeine content, and chlorogenic acid quantification) in green coffee and roasted coffee beans were performed; the sensory analysis was performed by a panel of trained tasters. The wet and semi-dry processing methods resulted in differences in color parameters, pH values, and caffeine content. However, the titratable acidity, chlorogenic acid, and sensory evaluation did not have any difference; therefore, the type of coffee processing method used is not relevant to the final chemical properties of the roasted coffee (i.e., the Castillo variety) evaluated in this study; the coffee cup score is also not affected, and the post-fermentation washing process can be dispensed with.

Resumo em Inglês:

ABSTRACT Knowledge regarding the static pressure drop in granular layers is of fundamental importance in the development of efficient drying and aeration projects of agricultural products. Thus, the objective of this study was to evaluate the effects of impurity contents on the static pressure drop in different bed depth of castor bean grains, as well as modify the mathematical models per the obtained experimental data and select the model that best represents this phenomenon. First, impurities in castor bean grains of the Guarani variety were eliminated and 6% of the moisture content (dry basis) was retained. The coarse impurity contents were obtained with 2%, 4%, and 6% of mass addition. The pressure drop in different bed depth of clean and impure castor bean grains were determined using an experimental determination equipment of pressure drop in bed depth with an airflow rate ranging 0.2 - 1.0 m3 s−1 m−2. The pressure drop linearly increases with an increase in the depth of the grain layer, and the increase in the airflow rate leads to an increased pressure drop in the castor bean grains layer. The impurity contents increase causes a reduction in pressure drop. The models that best represent castor beans grains pressure drop experimental data, without and with impurities, are Hukill & Ives (1955) and Nimkar & Chattopadhyay (2002), respectively.

Resumo em Inglês:

ABSTRACT This study aimed to evaluate drying kinetics for natural and pulped coffee, using different temperatures and drying airflows. For the conduction of the experiment, coffee fruits (Coffea arabica L. cv. Topázio) were harvested manually, selecting only ripe fruits and subsequent to the hydraulic separation. For drying the coffee, use a mechanical dryer with two temperatures (40 and 45°C) and four drying air streams (24; 60; 96 and 132 m3.min-1.m-2). Twelve models for employees to describe the drying kinetics of coffees. Among the models used to describe the drying process of natural coffee and pulped coffee, according to the results of the coefficient of determination, relative mean error, standard deviation of estimates and distribution of waste distribution, proposed model for the only one that presents fit for all as conditions study. The temperature of 45 ° C and the airflows of 96 and 132 m3.min-1.m-2 provide the shortest drying times regardless of the coffee processing type.

Resumo em Inglês:

ABSTRACT Cowpea beans are of great socioeconomic expression for the rural population in North and Northeastern Brazil. This legume is rich in essential nutrients and exhibits great resistance to water stress. However, for grain processing, it is fundamental to study legume behavior during the hydration process. This study aims to evaluate the mass transfer of different cowpea beans via mathematical modeling to determine the viability of hydration for commercialization as a canned product. Physical and chemical analyses of lipids and moisture were performed. The soaking process was performed in a water bath with distilled water at 30, 40, and 50 °C. The mathematical model of Peleg presented satisfactory adjustments, with R2 values ranging between 99.78% and 99.99% and relative error (P) of <3.74%. In addition, the influence of binomial time/temperature was observed during hydration.

Resumo em Inglês:

ABSTRACT Considering the importance of topographic surveys to determine soil volumes and study efficient and accessible alternatives for this operation, this study aimed to analyze methods and respective equipment for planialtimetric surveys to determine soil volume. An experimental grid was installed in an area locate in Fernandópolis, SP, Brazil, in which quotas were measured by geometric leveling (standard method), trigonometric leveling, leveling with receivers of the Global Navigation Satellite System (GNSS) by relative (frequencies L1/L2) and absolute positioning (code C/A) and extraction of altitudes in digital terrain model from SRTM and ASTER images. In comparison to geometric leveling, trigonometric leveling was the most accurate in determining soil volume (0.6% error), followed by GNSS leveling by relative positioning (23.7% error), and extraction of altitudes by SRTM (32.0% error) and ASTER images (38.3% error). GNSS leveling by absolute positioning presented the highest error in determining soil volume (287.4%) compared to the other methods.

Resumo em Inglês:

ABSTRACT The soaking and germination process of rice seeds is the starting point in rice cultivation in cold regions and has a significant effect on grain yield. Efficient techniques for controlling the water temperature in the seed tank are required to enhance germination quality. This paper introduces a fuzzy theory for designing a fuzzy logic-based sliding mode controller (SMC) system for a rice seed soaking and germination device. The proposed system was theoretically and experimentally investigated to determine the efficiency of the soaking temperature-control system. A modified fuzzy SMC based on exponent approaching law is also presented for optimizing the proposed controller. A proportional integral derivative (PID) controller was designed to identify and compare the advantages of the proposed controllers. A comparative study of the computer simulation demonstrates that the performance of fuzzy SMC and modified fuzzy SMC are acceptable, and that both SMCs are superior to the PID controller. Furthermore, compared with the fuzzy SMC system, a reduction in electric energy consumption was observed for the modified fuzzy SMC. Moreover, both SMCs yielded similar soaking qualities.

Resumo em Inglês:

ABSTRACT The need for accuracy in sugarcane machine traffic has boosted the adoption of automatic steering systems. These have been used in tractors pulling transhipment trailers. Such sets are long and articulated, which hinders their performance and benefits due to alignments in curved and laterally sloped paths. In this sense, this study aimed to quantify shifts in direction to which tractors and transshipment trailers are subjected while traveling straight and curved paths on different terrain slopes. We evaluated an internal transport system composed of one tractor and two three-axle transshipment trailers, equipped with GNSS receivers and RTK correction system, for their respective positioning. Pass-to-pass errors were evaluated by differences in orthogonal distance between antenna positioning and a reference line. Results showed that misalignment errors of tractor and trailer sets are strongly associated with path type and terrain lateral slope, besides being increasingly affected between set parts. Trailer path errors were above acceptable limits, thereby complementary solutions are needed regarding tractor automatic steering.

Resumo em Inglês:

ABSTRACT Wood has been used for several purposes such as in civil and rural construction. Knowing wood mechanical behavior under short-term loading is essential for safer structural designs. However, wood toughness is a mechanical property little investigated for this purpose. Thus, this study aimed to evaluate, using exponential and polynomial regression models (linear, quadratic, and cubic), the possibility of estimating toughness as a function of apparent density, compression parallel to grain strength, and modulus of rupture in static bending. Thirty-six Brazilian tropical wood species from south of Roraima, Mato Grosso do Sul, and north and northeast of Mato Grosso were tested. Our results showed the significance and representativeness of all investigated fits, among which a cubic polynomial function is the most indicated for wood toughness estimates.

Resumo em Inglês:

ABSTRACT This research aimed to evaluate the effect of the number of fatigue cycles (NC, 0 – reference, 450, 4500, 45000, and 90000) for frequencies (Fr) of oscillation equal to 0.5 and 1.0 Hz on the modulus of elasticity (Em) and operating stress (σm) in the static bending of Pinus caribaea wood. Em and σm were determined taking into account three specimens (SPEC) manufactured for reference condition and another three for each of the four NC levels and each Fr level, resulting in 27 SPEC. Sixty experimental determinations were obtained, being the approximate total time of sample exposure to fatigue of 350 hours. The same specimens used to determine Em and σm for the reference condition were also used (via non-destructive tests) to obtain these properties for all fatigue cycles. The frequency and number of cycles significantly influenced both investigated properties. Reductions in Em and σm values were observed after 45000 cycles. The progressive increase in the number of fatigue cycles caused more marked reductions in mechanical properties when compared to the increase in the frequency of oscillation.

Resumo em Inglês:

ABSTRACT The National Alcohol Program (Proálcool) was a strategic policy of the Brazilian government to replace petroleum-based fuels with alcohol (ethanol). Based on the review, we can choose the 1960s as a start point for a leap in development. Over the 500 years of sugarcane history in Brazil, the crop enters the second decade of the 21st century with extraordinary strength and prestige, reaching its highest production in history. This made Brazil a leader in sugar and ethanol productions worldwide, with an energy-independent agribusiness. Moreover, effluents and polluting wastes were transformed into high-value inputs (e.g., vinasse, filter cake, and others). Environmentally friendly actions included developing organic cane production technology, ceasing sugarcane field burning, relocating workers from field cutting activities, reducing atmospheric CO2 emissions. Besides, Brazilian agribusiness has led the search for the “philosopher's stone,” that is, transforming pulp or bagasse (polysaccharides) into fermentable sugar for second-generation ethanol production. This paper aimed to present the history and development of the Proálcool Program from decade to decade, as well as showing the actions that led Brazil to assume such significant leadership. This survey highlights the roles of the government, through the Sugar and Alcohol Institute, and of the agronomist Dr Gilberto Miller Azzi, who lent his name to the central building of the Center for Agricultural Sciences - UFSCar's Araras campus.

Resumo em Inglês:

ABSTRACT The sugar-energy sector stands out in the production of electrical energy in the Brazilian energy matrix. The updating of Law 9,427 allowed increasing the limit of power injected in the transmission or distribution systems of existing projects from 30 to 50 MW, encouraging studies of expansion and/or implementation of new cogeneration projects. This study analyzed technologies to enhance energy cogeneration in a plant that sells about 27 MW of surplus power. For this, were studied the use of straw, electrification of drives by steam turbines, and high-drainage rollers (lotus mill roller), which allows reducing bagasse moisture, increasing its lower calorific value (LCV) and, consequently, electrical energy generation. Mass and energy balances in the energy plants of the proposed cases were performed using the software IPSEpro®. Economic analyses were carried out using the conventional techniques of economic engineering (payback period, net present value – NPV, internal rate of return – IRR, and return on invested capital – ROIC). These analyses allowed the technical and economical identification of cases with viability, according to the value of the electrical energy sold.

Resumo em Inglês:

ABSTRACT The Darcy-Weisbach equation is the most recommended equation for determining the pressure loss in pressurized pipes because of its wide applicability. However, one of the largest obstacles to implementing this equation is the friction factor (f) calculation. This factor can be precisely determined using the Colebrook equation, which is implicit. Thus, the objective of this study was to compare six explicit equations for calculating the Darcy-Weisbach friction factor with the implicit Colebrook equation based on the relative error. Based on the results, the equations of Vatankhah and Offor & Alabi were the most highly recommended. These six explicit formulas showed a mean relative error of less than ± 1% compared to the Colebrook equation, except for the Swamee and Jain equation, for which the laminar regime generated a mean relative error of 1.83%.