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The flavor, aroma, and color of coffee can be changed due to mechanical damage, reducing its quality. To measure the mechanical behavior of the fruit, compression tests can be performed at different stages of ripeness. In this study, we analyzed the deformation, strain energy, and von Mises stress of coffee fruits at mature, semi-mature, and immature stages under compression forces. Compression in three directions (x, y, and z) was simulated on coffee fruit models using the finite element method. A compression support was applied in the opposite direction to the force application axis. Numerical simulations of the compression process allowed us to verify that the more mature the fruit, greater the associated mean deformation (2.20 mm mm−1, 0.78 mm mm−1, and 0.88 mm mm−1), the lower the mean strain energy (0.07 mJ, 0.21 mJ, and 0.34 mJ), and the lower the mean equivalent von Mises stress (0.25 MPa, 1.03 MPa, and 1.25 MPa), corresponding to ripe, semi-ripe, and immature fruits, respectively. These analyses not only save time and professional resources but also offer insights into how strain energy and von Mises stress affect fruits at different maturation stages. This information can guide machine adjustments to reduce coffee harvesting damages.

The mechanized harvesting of coffee fruits is performed by machines that uses the mechanical vibrations principles and has been widely adopted due the operational cost reductions compared to manual way. Maturation stages, frequency and amplitude of vibration influence the fruits detachment during the mechanized harvesting by mechanical vibrations. In this context, the determination of the modal parameters of the coffee plant is essential, considering, the full and selective harvesting. Modal analysis can be performed experimentally by using a specific instrumentation and, from this technique, it is possible to determine the vibration modes, damping factors and natural frequencies of the system in order to identify its dynamical behavior, supporting in the design and set-up of harvesting machines. In this way, this study was developed with the objective of determining and evaluating the modal characteristics of the coffee fruit-peduncle-branch system, such as the natural frequency, ratio and damping coefficient, from impact modal analysis. Additionally, the influence of the maturation stage, branch configurations (with/without leaves and fruits) and plant position in relation to the modal parameters of the system were evaluated. For branches without leaves and with fruits in different stages of maturation, several scenarios were studied. The results obtained verify that branches with ripe fruits (25.51 Hz, 24.19 Hz and 16.00 Hz for upper, middle and lower position in the plant, respectively) generally showed higher mean natural frequencies than branches with unripe fruits (16.77 Hz, 15.30 Hz and 15.49 Hz for upper, middle and lower position in the plant, respectively). For the complete branches with leaves and fruits, no significant differences in the first natural frequency were found between the mean natural frequencies throughout the plant and for different maturation stages. This pattern was repeated for the second and third natural frequencies, except for the difference in the average natural frequency found for branches with ripe fruits in the middle third of the plant. This behavior may be an important finding for the adjustment of harvesting machines since there was no differentiation between the average values of the natural frequency throughout the plant.

The search for alternative energy sources has fomented the study of several crops. The macauba palm crop, for instance, has been highlighted because of its particular relevance in Brazil due to its wide distribution across Brazilian territory and its potential for yielding high amounts of oil per cultivated hectare. However, the species is still most commonly harvested via extractivism, which results in low yields. Therefore, we aimed to analyze the dynamic behavior of the fruit-rachilla system when subjected to mechanical vibration to gather baseline information for the subsequent development of macauba harvesting machines. The fruit-rachilla system of the species was modeled for different fruit maturation stages and plant accessions. Natural frequencies and modes of vibration were determined by the stochastic finite element method (FEM), adopting the specific mass and the modulus of elasticity of the system as random variables, which enabled us to compile a dataset of natural frequencies based on the variability of the system properties. The mean values of the natural frequencies obtained in the vibration assays were 26.02 Hz at the green maturation stage and 21.22 Hz at the ripe maturation stage. The mean values of natural frequencies found in the simulation by stochastic FEM, referring to the third mode of vibration, were 26.05 Hz at the green maturation stage and 21.23 Hz at the ripe maturation stage. We concluded that the natural frequencies of the macauba fruit-rachilla system on the basis of different plant accessions showed a decreasing behavior during fruit maturation. The modes of vibration characterized by pendulum displacement did not differ among plant accessions or between fruit maturation stages.

Macaw (Acrocomia aculeata) is a product of Brazilian socio-biodiversity and is an excellent source of oil for the cosmetics, food and fuel industry. One of the technical bottlenecks of macaw fruit production is the manual harvesting with rudimentary tools and the extractive system, which has a very large dependence on labor. The objective of this work was to develop the informational and conceptual design of a semi-mechanized harvesting system that can be used in adverse conditions of relief, also directed to the needs of family farmers. In this work the concept of a low cost macaw harvester is proposed, which works by the principle of mechanical vibrations, and is able to work efficiently in planted and natural plantations. From an adaptation of the Pahl and Beitz method for the development of machine designs, and the use of the evolution prototyping method, integration prototypes were constructed, which underwent a preliminary field test. Some modifications were made in portable coffee breakers, which constituted changes in the vibration signal generation system that were transmitted to macaw fruits at the head / plant interface. Only one of the built prototypes was considered effective and suitable for subsequent performance (product under patent registration). For the detailed design, CAD (Computer Aided Design) techniques were employed. Later, it was possible to observe the validation of efficiency of the macaw fruit harvest by the principle of mechanical vibrations. Under field conditions, field trials demonstrated that the average harvest efficiency for the proposed model with vibrating rods was 97.4% and the average harvesting capacity was 566.91 kg h-1.

The fruit of the native macaw palm [Acrocomia aculeata (lacq) Lood. ex Mart] is an alternative for biodiesel production because of the plant characteristics, as well as its adaptability, hardiness and high vegetable oil yield. However, its exploitation remains extractive and there are significant difficulties in its harvest. This study aimed to determine the mechanical properties of the macaw palm fruit-rachilla system that will support the design of harvest machines based on mechanical vibration. Ten samples of four accessions in the immature and mature stages of maturity were used. Traction and vibration tests were conducted to determine the mechanical properties of the macaw palm fruit-rachilla system. The elastic modulus of the rachilla was 188.39-385.09 MPa for the immature stage and 109.02-320.54 MPa for the mature stage. The Poisson's ratio for the rachilla varied between 0.20 and 0.52 for the immature stage and between 0.16 and 0.52 for the mature stage. The damping ratio varied between 0.02 and 0.12 for the immature stage and between 0.06 and 0.12 for the mature stage. The fruit-rachilla system was characterized as underdamped.

Design of an agricultural machine is a highly complex process due to interactions between the operator, machine, and environment. Mountain coffee plantations constitute an economic sector that requires huge investments for the development of agricultural machinery to improve the harvesting and post-harvesting processes and to overcome the scarcity of work forces in the fields. The aim of this study was to develop a preliminary design for a virtual prototype of a coffee fruit harvester. In this study, a project methodology was applied and adapted for the development of the following steps: project planning, informational design, conceptual design, and preliminary design. The construction of a morphological matrix made it possible to obtain a list of different mechanisms with specific functions. The union between these mechanisms resulted in variants, which were weighed to attribute scores for each selected criterion. From each designated proposal, two variants with the best scores were selected and this permitted the preparation of the preliminary design of both variants. The archetype was divided in two parts, namely the hydraulically articulated arms and the harvesting system that consisted of the vibration mechanism and the detachment mechanism. The proposed innovation involves the use of parallel rods, which were fixed in a plane and rectangular metal sheet. In this step, dimensions including a maximum length of 4.7 m, a minimum length of 3.3 m, and a total height of 2.15 m were identified based on the functioning of the harvester in relation to the coupling point of the tractor.

Numerical implementation methods such as the finite element method can be used in machine design to study the dynamic behavior of the plant. Input parameters for using the finite element method should be set based on the geometrical, physical and mechanical system under study. Thus, the aim of this study was to determine the mechanical properties of the rachis of macaw palm in the green maturation stage at an age of 180 days and at fruit maturation. The water content was calculated using the oven method of 105 ± 3°C for 24 hours. The modulus of elasticity for the rachis was determined by means of mechanical compression testing. The Poisson's ratios were determined from the results of the longitudinal and transverse deformation of rachis test bodies. The shear tests were performed in two scenarios. In the first one, a blade was used without a tensioner, and in the second scenario, a blade was fixed with a tensioner, characterized by a chamfer at 45°. It was concluded that the modulus of elasticity of macaw palm rachis in the green maturity stage was higher than the values for the mature stage of ripeness.

A macaúba (Acrocomia aculeata) é um produto da sociobiodiversidade brasileira e é uma excelente fonte de óleo para a indústria cosmética, de alimentos e de combustíveis. Um dos gargalos técnicos da produção dos frutos da macaúba é a colheita feita de forma manual com ferramentas rudimentares e no sistema extrativista, que tem dependência muito grande de mão de obra. Objetivou-se com o presente trabalho desenvolver o projeto informacional, conceitual e detalhado de um sistema semi-mecanizado de colheita que possa ser utilizado em condições adversas de relevo. Foi proposto o conceito de um mecanismo colhedor de macaúbas, de baixo custo, que funciona pelo princípio de vibrações mecânicas, e é capaz de trabalhar com eficiência em lavouras plantadas e maciços naturais. A partir de uma adaptação do método de Pahl e Beitz para desenvolvimento de projetos de máquinas, e a utilização do método de prototipagem de evolução, foram construídos protótipos de integração, que passaram por ensaio preliminar de campo. Foram realizadas algumas modificações em derriçadoras portáteis de café, que se constituíram em alterações no sistema de geração de sinais de vibração e foram transmitidos aos frutos de macaúba, na interface cabeçote/planta. Apenas um dos protótipos construídos foi considerado eficaz e adequado para realização posterior de avaliação de desempenho (protegida por meio de depósito de pedido de patente junto ao Instituto Nacional da Propriedade Industrial - INPI, sob o n.º BR 10 2017 010814 7). Para o projeto detalhado foram empregadas técnicas de CAD (Projeto Auxiliado por Computador). Posteriormente, foi possível observar a validação de eficiência da colheita dos frutos de macaúba pelo princípio de vibrações mecânicas. Nas condições em que ocorreram, os ensaios de campo demonstraram que a média da eficiência de colheita para o modelo proposto com varetas vibratórias foi de 97,4% e a média da capacidade de colheita foi de 566,91 kg h- 1.

The development of efficient machines for the mechanical harvesting of coffee plants requires the use of appropriate vibrational parameters. Thus, in order to detach less unripe fruits and decrease reharvesting, branch breakage and defoliation, it is important to choose the appropriate frequency, amplitude and vibration time. This study aimed at analyzing the detachment efficiency of fruits from coffee plants according to vibrational parameters and ripening stage. Fruit bunches were sampled at the green and mature stages and subjected to vibration, using a system composed by a signal generator, an amplifier and an electromagnetic vibrating machine. Tests combined different frequencies (16.4 Hz, 20.3 Hz, 24 Hz, 25.6 Hz, 30.0 Hz and 33.0 Hz), amplitudes (5.0 mm, 7.0 mm and 9.0 mm) and vibration times (10.0 s and 20.0 s). The vibration times did not affect the detachment efficiency. There was a trend for higher detachment efficiency in mature fruits than in green fruits. The detachment efficiency increased with increasing vibration frequency and amplitude.

O transplantio semi-mecanizado de mudas de tomate industrial tem se tornado uma alternativa viável para os produtores, visto que possibilita o aumento da capacidade operacional. Com o objetivo de avaliar a influência da velocidade de operação e repasse dos trabalhadores do campo no estande final, o trabalho foi conduzido em uma área de 58 ha irrigada por meio de um pivô central. O presente trabalho foi realizado a partir da implantação do híbrido HEINZ 9553, empregando uma transplantadora da marca Ferrari modelo FX, tracionada por um trator da marca New Holland, modelo TM 7010, 4x2 com tração dianteira auxiliar. As velocidades analisadas foram de 1,83; 1,66 e 1,56 km h-1, sendo que a contagem das mudas foi obtida após a demarcação e a passagem do conjunto mecanizado pelas parcelas delimitadas. A análise da influência da velocidade no transplantio foi realizada por meio da utilização de cartas de controle e da média móvel exponencialmente ponderada (MMEP), na qual os dados foram analisados em função das velocidades e dos estandes estimados em cada ponto. As velocidades de transplantio modificaram os estandes finais nos processos estudados e esse fato pode ser explicado devido a uma falta de uniformidade de espaçamento entre as mudas transplantadas. Apenas na velocidade de 1,83 km h-1 todas as observações se mantiveram sob controle em ambas as situações. O controle estatístico de processos através da utilização de cartas de controle e da média móvel exponencialmente ponderada foram ferramentas adequadas para avaliação do estande final. = The tomato semi-mechanized transplanting has become a viable alternative for producers, since it allows increased operational capacity of fieldwork. In order to evaluate the influence of operating speed of the transplanting process, a study was conducted in an experimental area of 58 ha irrigated by a center pivot. This study was conducted from the deployment of the hybrid HEINZ 9553, using a Ferrari transplantation engine model FX, pulled by a tractor New Holland brand, model TM 7010, 4x2 front wheel assist (TDA). Transplanting speeds evaluated were 1.83; 1.66 and 1.53 km h-1, and the seedling count was obtained after passage of demarcation of mechanized set in the delimited plot areas. The effect of the transplantation speed was analyzed by using control charts and exponentially weighted moving average (MMEP), in which the data were analyzed considering the different speeds and the estimated seedling stands at each point. All observations remained under control only at the operating speed of 1.83 km h-1. Transplanting speeds affected final plant stands in all processes studied and this may be explained by poor uniformity of seedlings transplanted. For higher operating speeds, seedling deposition uniformity in the soil was negatively affected, which resulted in increased work done by laborers required for seedling replant. The use of control charts and exponentially weighted moving average were appropriate tools for assessing the final stand.

Flowability is an important characteristic of handling process for efficiency and reliability purpose of post-harvest operations, which are governed by the physical properties of the product. Physical properties determination is an important factor for formulation of machinery projects and sizing of post-harvest operations, which may impact considerably on the products quality, influencing directly the operation cost and company profit. Thus, the objective of this work was to evaluate and determinate some physical properties (repose angle, unit and bulk density, porosity and color coordinates, particle size, moisture content, water activity, angle of internal friction and effective angle of internal friction) of coffee, such as to evaluate the influence of different roast and grinding degrees over these properties. Crude grain coffee (Coffea canephora and Coffea arabica), dehulled and dried were used. These were roasted at two levels: medium light and medium-dark brown, which Agtron numbers are, respectively, SCAA#65 and SCAA#45. After roasting process, grains were grinded at three particle sizes (thin, medium and thick). Both particle size and roast degree significantly affected physical properties of coffee. Coffee samples roasted at medium dark level obtained lower values of moisture content, water activity, repose angle, bulk and real density. Coffee samples grinded at level thin presented an increase of angle of internal friction and effective angle of internal friction, repose angle, bulk and real density, porosity and decrease of water activity values.

Losses in the mechanical harvesting of industrial tomatoes, depending on the levels reached, may considerably reduce the yield of the planted areas. This study aimed to evaluate the effect of settings of the rotary separation system on losses observed during the mechanized harvesting process. The statistical design was completely randomized, in a factorial scheme with four replications, where each plot consisted of the combination of three rotation levels (6 rpm, 24 rpm and 18 rpm) with three vibration frequencies (0.83 Hz, 2.50 Hz and 4.17 Hz) from the separation system. The recorded losses were divided into branch losses, fruit losses on the soil and total losses. Sequential and control charts for individual values and variable ranges composed by the upper and lower limits of control and average were used as a tool of statistical process control. The results showed that the total losses incurred are outside the control limits and acceptable standards for industrial tomato crops. The use of higher levels of rotation and vibration in the harvester separation system provided a higher harvest efficiency.

Considering the importance of mathematical models in the development and analysis of grain drying systems, and understanding the need to develop interfaces that will improve the accessibility of these models, this work aimed to: a) implement the Thompson model to simulate grain drying at high temperatures; b) develop an appropriate language to generate drying models; and c) develop a graphical interface with the goal of facilitating user understanding. Thus the computational program LINSEC that was created using the programming language Visual Basic 6.0. LINSEC was highly effective for the modeling and simulation of drying systems and in providing simulated values close to reality. LINSEC is highly flexible and user-friendly during the modeling of several types of dryers.Tendo em vista a importância dos modelos matemáticos no desenvolvimento e análise de sistemas de secagem, além do conhecimento e necessidade de desenvolver interfaces de modo a aprimorar a acessibilidade e uso destes modelos, este trabalho visou: a) implementar o modelo de Thompson de modo a simular a secagem de grãos a altas temperaturas; b) desenvolver uma linguagem apropriada para gerar sistemas de secagem; e c) desenvolver uma interface gráfica com o objetivo de facilitar o entendimento do usuário, utilizando-se a linguagem Visual Basic 6.0. O programa computacional LINSEC, demonstrou uma alta efetividade na simulação de secagem, fornecendo valores próximos à realidade. É flexível e de fácil utilização pelo usuário durante a simulação para diferentes tipos de secadores.

Precision agriculture that is based on the physical and chemical properties of soil requires a dense sampling to evaluate spatial variability in the field. This dense sampling is often expensive and time consuming. One technique to reduce the number of samples is to define management zones based on information that is collected in the field. Some researchers have demonstrated the importance of the electrical properties of soil in defining management zones. Thus, the objective of this study was to evaluate the relationship between the apparent soil electrical conductivity and soil properties in mountainous areas of coffee production. The electrical conductivity of soil was evaluated at soil depths ranging from 0.00-0.20 m (EC20) and 0.00-0.40 m (EC40) using a portable meter. The mean values of EC20 and EC40 were 1.80 mS m-1 and 1.22 mS m-1, respectively. Both EC20 and EC40 exhibited comparatively low correlations with the soil properties, whereas higher correlations were obtained for measurements of remaining phosphorus, wherein values of 0.427 and 0.465, respectively, were obtained.A agricultura de precisão baseada nas propriedades físicas e químicas do solo exige uma amostragem densa para se determinar a variabilidade espacial no campo. Essa amostragem densa, muitas vezes apresenta custo e tempo consumido elevado. Uma das técnicas para reduzir o número de amostras é definir zonas de manejo em função de informações coletadas no campo. Alguns pesquisadores têm demonstrado a importância desempenhada pelas variáveis elétricas do solo para definir zonas de manejo. Dessa forma, este trabalho teve como objetivo avaliar a relação entre a variabilidade espacial da condutividade elétrica aparente e propriedades do solo em regiões de produção de cafés de montanha. A condutividade elétrica foi medida no perfil de solo de 0,00-0,20 m (CE20) e 0,00-0,40 m (CE40) usando um sensor portátil. Os valores de CE20 e CE40 foram de 1,80 mS m-1 e 1,22 mS m-1, respectivamente. Ambas CE20 e CE40 apresentaram baixa correlação com as propriedades químicas e a textura do solo, sendo que, a correlação mais elevada foi obtida para o fósforo remanescente com valores de 0,427 e 0,465, respectivamente.

Fertilizer application at variable rates requires dense sampling to determine the resulting field spatial variability. Defining management zones is a technique that facilitates the variable-rate application of agricultural inputs. The apparent electrical conductivity of the soil is an important factor in explaining the variability of soil physical-chemical properties. Thus, the objective of this study was to define management zones for coffee (Coffea Arabica L.) production fields based on spatial variability of the apparent electrical conductivity of the soil. The resistivity method was used to measure the apparent soil electrical conductivity. Soil samples were collected to measure the chemical and physical soil properties. The maps of spatial variability were generated using ordinary kriging method. The fuzzy k-means algorithm was used to delimit the management zones. To analyze the agreement between the management zones and the soil properties, the kappa coefficients were calculated. The best results were obtained for the management zones defined using the apparent electrical conductivity of the soil and the digital elevation model. In this case, the kappa coefficient was 0.45 for potassium, which is an element that is associated with quality coffee. The other variable that had a high kappa coefficient was remaining phosphorous; the coefficient obtained was 0.49. The remaining phosphorus is an important parameter for determining which fertilizers and soil types to study.

An important factor for the evaluation of an agricultural system’s sustainability is the monitoring of soil quality via its physical attributes. The physical attributes of soil, such as soil penetration resistance, can be used to monitor and evaluate the soil’s quality. Artificial Neural Networks (ANN) have been employed to solve many problems in agriculture, and the use of this technique can be considered an alternative approach for predicting the penetration resistance produced by the soil’s basic properties, such as bulk density and water content. The aim of this work is to perform an analysis of the soil penetration resistance behavior measured from the cone index under different levels of bulk density and water content using statistical analyses, specifically regression analysis and ANN modeling. Both techniques show that soil penetration resistance is associated with soil bulk density and water content. The regression analysis presented a determination coefficient of 0.92 and an RMSE of 0.951, and the ANN modeling presented a determination coefficient of 0.98 and an RMSE of 0.084. The results show that the ANN modeling presented better results than the mathematical model obtained from regression analysis.Um importante fator para a avaliação da sustentabilidade de sistemas agrícolas é o monitoramento da qualidade do solo por meio de seus atritutos físicos. Logo, atributos físicos do solo, como resistência à penetração, podem ser empregados no monitoramento e na avaliação da qualidade do solo. Redes Neurais Artificiais (RNA) tem sido empregadas na solução de vários problemas na agricultura, neste contexto, o uso desta técnica pode ser considerada uma abordagem alternativa para se predizer a resistência à penetração do solo a partir de suas propriedades básicas como densidade e teor de água. Portanto, o objetivo desse trabalho foi desenvolver um estudo do comportamento da resistência à penetração do solo, medida a partir do índice de cone, empregando análise de regressão e modelagem por RNA. Ambas as técnicas mostraram que a resistância à penetração do solo está associada com a densidade e o teor de água do solo. A análise de regressão apresentou coeficiente de regressão de 0,92 e REMQ igual a 0,951 enquanto a modelagem por RNA apresentou coeficiente de determinação de 0,98 e REMQ igual a 0.084. Os resultados indicaram que a modelagem por RNA apresentou melhores resultados do que o modelo matemático obtido a partir da análise de regressão.

Harvesting is one of the most important operations in coffee production systems. This operation has a high cost and impact on the final quality of the product. To reduce production costs, producers are looking for ways to mechanize this operation. Harvesting machines generally detach fruits from the coffee plant by vibration and/or impact. The objective of this work was to study the effect of the amplitude and frequency of vibration on the efficiency of coffee fruit harvesting. Vibration tests of coffee branches were performed in a laboratory using an electromagnetic shaker. The tests were performed using amplitudes in the range of 3.75 to 7.50 mm and frequencies from 13.33 to 26.67 Hz. Coffee branches from two different varieties were used for evaluation, Catuaí Vermelho and Mundo Novo. It was verified that harvesting efficiency is directly related to the acceleration reached by the fruits during the harvesting process. The frequencies of 23.33 and 26.67 Hz and amplitudes of 6.25 and 7.50 mm resulted in the highest harvesting efficiency of ripe coffee cherries for both varieties. However, theharvesting efficiency for the Mundo Novo variety was higher than that of the Catuaí Vermelho variety at the studied frequency and amplitude ranges in this work.A colheita é uma das operações mais importantes no sistema de produção do café pelo seu elevado custo e ao impacto que tem na qualidade do produto final. Para reduzir os custos de produção, têm-se buscado formas de mecanizar essa operação. As máquinas de colheita de café geralmente derriçam os frutos por meio de vibrações mecânicas e impacto. Este trabalho foi desenvolvido com o objetivo de estudar o efeito da amplitude e da frequência de vibração sobre a eficiência de derriça dos frutos de café. Para isso, ensaios usando uma máquina vibradora eletromagnética foram realizados em laboratório. Foram testadas amplitudes na faixa de 3,75 a 7,50 mm e frequências na faixa de 13,33 a 26,67 Hz. Os testes foram conduzidos utilizando-se ramos das variedades Catuaí Vermelho e Mundo Novo. A partir da análise dos resultados verificou-se que a eficiência de derriça dos frutos está diretamente relacionada à aceleração imposta aos frutos durante o procedimento de derriça. As frequências entre 23,33 e 26,67 Hz e amplitudes que variam entre 6,25 e 7,50 mm proporcionaram maior eficiência de derriça dos frutos cereja para ambas as variedades estudadas. A eficiência de derriça por vibração na variedade Mundo Novo foi superior à da variedade Catuaí Vermelho para os intervalos de frequência e amplitudes avaliados.

Harvesting is one of the most important operations in coffee production systems. This operation has a high cost and impact on the final quality of the product. To reduce production costs, producers are looking for ways to mechanize this operation. Harvesting machines generally detach fruits from the coffee plant by vibration and/or impact. The objective of this work was to study the effect of the amplitude and frequency of vibration on the efficiency of coffee fruit harvesting. Vibration tests of coffee branches were performed in a laboratory using an electromagnetic shaker. The tests were performed using amplitudes in the range of 3.75 to 7.50 mm and frequencies from 13.33 to 26.67 Hz. Coffee branches from two different varieties were used for evaluation, Catuaí Vermelho and Mundo Novo. It was verified that harvesting efficiency is directly related to the acceleration reached by the fruits during the harvesting process. The frequencies of 23.33 and 26.67 Hz and amplitudes of 6.25 and 7.50 mm resulted in the highest harvesting efficiency of ripe coffee cherries for both varieties. However, the harvesting efficiency for the Mundo Novo variety was higher than that of the Catuaí Vermelho variety at the studied frequency and amplitude ranges in this work.

ABSTRACT: The macaw palm has been identified as a prime feed stock for biodiesel industries in the near future coming decades. However, there are no machines for harvesting and detaching fruits in the biofuel industry; hence, the study of the dynamic behavior of the fruit-rachilla system would aid in the development of such machines. Thus, this study seeks to determine the modulus of elasticity and the damping ratio of four different plant accessions obtained from the Active Germplasm Bank of the Universidade Federal de Viçosa (UFV). Tensile testing was conducted to determine the modulus of elasticity. From the graphical results of tension versus specific strain, it was possible to determine the modulus of elasticity by using the tangent method. To determine the damping ratio, the logarithmic decrement method was performed using vibration testing. Vibration test consisted of a generated impulse of 100% of the amplitude of acceleration that was used to excite the system. The acquisition of the generated information was performed by a piezoelectric accelerometer. The average modulus of elasticity ranged from 2.22 to 3.17MPa, and the average damping ratios ranged from 0.04 to 0.08. Thus, the macaw fruit-rachilla was an under-damped system.