Navegando por Autor "Santos, Fábio Lúcio"
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Item Analysis of the coffee harvesting process using an electromagnetic shaker(Acta Scientiarum. Agronomy, 2010-07) Santos, Nerilson Terra; Santos, Fábio Lúcio; Queiroz, Daniel Marçal de; Pinto, Francisco de Assis de CarvalhoHarvesting 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, Catuai 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 Catuai Vermelho variety at the studied frequency and amplitude ranges in this work.Item Detachment efficiency of fruits from coffee plants subjected to mechanical vibrations(Pesquisa Agropecuária Tropical, 2015-11) Pinto, Francisco de Assis de Carvalho; Coelho, Andre Luiz de Freitas; Santos, Fábio Lúcio; Queiroz, Daniel Marçal deThe 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.Item Determination of modal properties of the coffee fruit-stem system using high speed digital video and digital image processing(Acta Scientiarum, 2015-09-21) Villibor, Geice Paula; Santos, Fábio Lúcio; Queiroz, Daniel Marçal de; Khoury Junior, Joseph Kalil; Pinto, Francisco de Assis de CarvalhoDetachment of coffee fruit is usually accomplished by means of mechanical impacts and vibrations applied to the plant. Modal properties of the coffee fruit-stem system represent important information for efficient and selective harvesting. This study aimed to determine the modal parameters of the coffee fruit-stem system, such as natural frequency and damping coefficient, using high speed digital videos. With image processing techniques, it was obtained the resulting displacement of the system subjected to an impulse. The modal parameters were determined by the logarithmic decrement method, considering the system as underdamped. The use of high-speed video and digital image processing techniques allowed the simple and reliable determination of modal parameters of the coffee fruit-stem system. Natural frequencies for the coffee fruit-stem system were 11.62 and 13.29 Hz; the damping coefficient was 0.0253 and 0.029 N s m -1 , and the equivalent stiffness was 8.61 and 7.09 N m -1 for red and green ripening stages, respectively. It was found overlap of resonance bands, between the ripening stages red and green, hindering the selective mechanical detachment in the first natural frequency range of the coffee fruit-stem system.Item Elasticity modulus and damping ratio of macaw Palm rachillas(Ciência Rural, 2016-11-14) Villar, Flora Maria de Melo; Pinto, Francisco de Assis de Carvalho; Santos, Fábio Lúcio; Grossi, José Antônio Saraiva; Velloso, Nara SilveiraThe 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.Item Experiência em capacitação de agricultores familiares em uso e manutenção de roçadoras e derriçadoras portáteis(Revista ELO - Diálogos em Extensão, 2013-12) Grupioni, Christina Maria de Freitas; Santos, Fábio LúcioExperimento conduzido em comunidades rurais de Espera Feliz, MG, onde foram realizados treinamentos pilotos como etapa inicial de um trabalho de extensão. Foram atendidos cinquenta e oito agricultores. O objetivo do trabalho foi atender a demanda de capacitação de agricultores familiares na área de mecanização agrícola. Dialogou-se com os agricultores por meio de vivências individuais, a partir das quais foram debatidas as normas de segurança, a necessidade do uso de equipamentos de proteção individuais (EPI’s) adequados e a importância da manutenção preventiva, o uso indiscriminado de agrotóxicos e a função da roçadora para diminuir esse uso. Foi aplicado um questionário constituído de questões envolvendo relatos de acidentes ocorridos com os trabalhadores durante a operação das máquinas. Foram identificados dezesseis casos de acidentes. Os treinamentos apontaram para a carência de ocorrência de atividades de extensão na zona rural e evidenciaram a falta de uso adequado de EPI’s.Item Influence of the impact of a rigid rod on the coffee fruits detachment by mechanical vibrations(Revista Agrarian, 2016) Gomes, Ely Queiroz; Santos, Fábio Lúcio; Jesus, Valquíria Aparecida Mendes deNowadays, the coffee sector has passed by a transition due the lack of labor, which makes manual harvesting unfeasible. The mechanization has been the solution found by the coffee farmers to overcome the problem of lack of labor and also reduce the production costs. The aim of this study was to evaluate the detachment efficiency behavior of the coffee fruits under mechanical vibrations transmitted to the fruit-stem system by impact of a rigid rod, and mechanical vibrations transmitted to the system without the impact. Trials to evaluate the fruits detachment were performed varying the vibration frequency, the ripening stage of the fruits, the number of fruits at the same stem and the way of transmission of the mechanical vibrations to the fruit-stem system. The detachment efficiency of red fruits was higher than green fruits. It was observed an increase of the detachment efficiency associated to the increase the frequency of vibration. Detachment efficiency obtained from mechanical vibrations transmitted due the impact of a rigid rod on fruit-stem system was 19.4% higher than mechanical vibrations transmitted without impact.Item Mechanical properties of the macaw palm fruit-rachilla system(Pesquisa Agropecuária Tropical, 2017-06) Pinto, Francisco de Assis de Carvalho; Villar, Flora Maria de Melo; Valente, Domingos Sárvio Magalhães; Velloso, Nara Silveira; Santos, Fábio LúcioThe 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.Item Mechanical properties of the macaw palm fruit-rachilla system(Pesquisa Agropecuária Tropical, 2017-04) Pinto, Francisco de Assis de Carvalho; Villar, Flora Maria de Melo; Valente, Domingos Sárvio Magalhães; Velloso, Nara Silveira; Santos, Fábio LúcioThe 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.Item Mechanical properties of the rachis from macaw palm bunches(Acta Scientiarum. Agronomy, 2018-01) Oliveira, Zenil Ricardo Cunha Rodrigues de; Valente, Domingos Sarvio Magalhães; Pinto, Francisco de Assis de Carvalho; Santos, Fábio Lúcio; Velloso, Nara SilveiraNumerical 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.Item Morphology and anatomy of the seedling and the tirodendro of Calophyllum brasiliense Cambess. (Clusiaceae)(Acta Scientiarum. Biological Sciences, 2014-02-06) Jesus, Valquíria Aparecida Mendes de; Braccini, Alessandro Lucca; Souza, Luiz Antonio de; Moscheta, Ismar Sebastião; Mariucci, Giovanna Emanuelle Gonçalves; Santos, Fábio LúcioCalophyllum brasiliense Cambess. is a tree species that is presented as an alternative to replace endangered species of hardwood. The morphology and anatomy of the seedling of this species is the object of the present study. Seedlings at different stages of development were obtained in greenhouse and analyzed fresh and fixed in FAA (Formalin-Acetic-Alcohol) 50. The anatomical analysis was done by the freehand and microtome sections, according to standard techniques in plant anatomy. The seedling and/or tirodendro is cryptocotylar and hypogeal, has cataphylls, and presents eophylls and metaphylls simple with venation pinnate craspedodromous simple. The root is polyarch, the hypocotyl is very short, the cotyledons have an oily and starchy reserve, the epicotyl has stem structure, and eophylls and metaphylls are dorsiventral. The seedling may be classified in the Horsfieldia type/subtype.Item Perdas na colheita de tomate industrial em função da regulagem da colhedora(Pesquisa Agropecuária Tropical, 2014-10) Santos, Fábio Lúcio; Cunha, João Paulo Barreto; Machado, Túlio de Almeida; Coelho, Laysla MoraesAs perdas na colheita mecanizada de tomate industrial, dependendo dos níveis atingidos, podem reduzir consideravelmente a produtividade das áreas plantadas. Dentro desse contexto, este estudo objetivou avaliar o efeito da regulagem do sistema de separação rotativo nas perdas observadas durante a realização da colheita mecanizada. O delineamento estatístico utilizado foi inteiramente casualizado, em esquema fatorial, com quatro repetições, onde cada parcela consistiu da combinação de três níveis de rotação (6 rpm, 12 rpm e 18 rpm) e três frequências de vibração (0,83 Hz, 2,50 Hz e 4,17 Hz) do sistema de separação. As perdas contabilizadas foram divididas em perdas nas ramas, perdas de frutos no solo e perdas totais. Cartas sequenciais e cartas de controle para valores individuais e de amplitude móveis, compostas pelos limites superior e inferior de controle e média, foram utilizadas como ferramentas de controle estatístico de processo. Os resultados indicaram que as perdas totais ocasionadas encontram-se fora dos limites de controle e dos padrões aceitáveis para a cultura do tomate industrial. A adoção de maiores vibrações e rotações do sistema de separação da colhedora proporcionaram maior eficiência de colheita.Item Perdas na plataforma de corte de uma colhedora combinada de grãos na colheita de soja(Engenharia na Agricultura, 2012-09-25) Machado, Túlio de Almeida; Santos, Fábio Lúcio; Cunha, João Paulo Barreto; Cunha, Daniel Antônio da; Coelho, Laysla MoraisA soja (Glycine Max) é uma das espécies mais cultivadas no Brasil, com importante papel socioeconômico e produção estimada para a safra 2011/12 de 66,7 milhões de toneladas. Dentre os prejuízos no processo de colheita, as ocasionadas pelo mecanismo de corte da colhedora são significativas, correspondendo cerca de 85% das perdas totais durante a colheita mecanizada. Este trabalho foi desenvolvido com o objetivo de avaliar as perdas na plataforma de corte em diferentes configurações de operação. O estudo foi conduzido na fazenda Santa Rosa, localizada no município de Morrinhos-GO, em uma área de 58 ha irrigada por pivô central onde foi realizada a semeadura da variedade IGRA 516 RR. Como fonte de avaliação do estudo, foi utilizada uma colhedora da marca John Deere, modelo 1450. O experimento foi realizado em delineamento de blocos casualizados em esquema fatorial 2x3, com duas velocidades de operação e três rotações do molinete e sete repetições, totalizando 42 unidades experimentais. Os resultados mostram que as perdas na plataforma de corte foram significativas em função da interação dos fatores estudados, sendo os melhores resultados obtidos quando utilizado 30 rpm na rotação do molinete e 5 km h-1 para a velocidade de avanço, totalizando perdas entre 25,8 e 54,6 kg ha-1.Item Physical characterization of coffee after roasting and grinding(Semina: Ciências Agrárias, 2014-10-24) Oliveira, Gabriel Henrique Horta de; Corrêa, Paulo Cesar; Santos, Fábio Lúcio; Vasconcelos, Wander Luiz; Júnior, Carlito Calil; Baptestini, Fernanda Machado; Vargas-Elías, Guillermo AsdrúbalA escoabilidade é uma importante característica do manuseio para a eficiência e a confiabilidade das operações pós-colheita, sendo regida pelas propriedades físicas do produto. A determinação das propriedades físicas é um importante fator na formulação de projetos de maquinários e dimensionamento de operações pós-colheita, podendo impactar consideravelmente na qualidade do produto, influenciando diretamente o custo da operação e o lucro da empresa. Assim, objetivou-se avaliar e determinar as propriedades físicas: ângulo de repouso, massa específica unitária e aparente, porosidade e as coordenadas de cor, análise da granulometria, teor de água, atividade de água, ângulo de atrito interno e efetivo ângulo de atrito interno do café, bem como avaliar a influência de diferentes níveis de torra e granulometria sobre essas propriedades. Foram utilizados grãos de café cru (Coffea canephora e Coffea arabica), descascados e secos, e torrados em dois níveis: média clara (SCAA#65) e moderadamente escura (SCAA#45). Após a torrefação, os grãos foram moídos em três granulometrias: fina (0,59 mm), média (0,84 mm) e grossa (1,19 mm), segundo normas de classificação da ABIC, além de mantido o lote de café inteiro. A granulometria e o nível de torrefação afetaram significativamente as propriedades físicas do café. As amostras de café torradas ao nível moderadamente escuro obtiveram menores valores de teor de água, atividade de água, ângulo de repouso, massa específica unitária e aparente. Já os cafés de granulometria mais fina apresentaram aumento de ângulo de atrito interno e efetivo ângulo de atrito interno, ângulo de repouso, massa específica unitária e aparente, porosidade e decréscimo de atividade de água.Item Preliminary design of a coffee harvester(Semina: Ciências Agrárias, 2016-06-13) Moreira, Raphael Magalhães Gomes; Teixiera, Mauri Martins; Santos, Fábio Lúcio; Fernandes, Haroldo Carlos; Cecon, Paulo RobertoDesign 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.Item Simtrac – an application for simulation of traction efficiency of agricultural tractors with front wheel assist(Acta Scientiarum, 2016-02-26) Queiroz, Daniel Marçal de; Santos, Fábio LúcioProcess mechanization has contributed significantly to the increase of agricultural productivity, although the correct selection of machines must take into account a set of technical, administrative and economic parameters. Mathematical modeling of the soil and traction device interaction allows researchers and designers to analyze problems associated to traction performance in tractors and to optimize operational parameters. Mobile devices have currently dominated the technological market. Smartphones and tablets feature mobility and great processing capacity and these characteristics have favored the development and the insertion of applications in many fields. Current research developed an application to simulate the traction capacity of agricultural tractors with front wheel assist. The application was developed with Android platform, version 2.3 ‘Gingerbread’. The application is intuitive and easy to operate, besides showing great flexibility. It may be used in schools and in research to optimize agricultural operations. Concordance between simulated and observed results, obtained from validation process, demonstrated the prediction capacity of the traction efficiency of agricultural tractors. Further, it has been verified that input parameters associated to surface conditions are fundamental for the simulation of traction efficiency.Item Simulação e avaliação do comportamento dinâmico de frutos do cafeeiro na derriça(Universidade Federal de Viçosa, 2008-01-28) Santos, Fábio Lúcio; Pinto, Francisco de Assis de Carvalho; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4784515P9; Santos, Nerilson Terra; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4782537A2; Queiroz, Daniel Marçal de; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4783625P5; http://lattes.cnpq.br/9958949069384359; Khoury Junior, Joseph Kalil; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4760449Z9; Martins, Márcio Arêdes; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4798288T8; Salvador, Nilson; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4784804E0A colheita pode ser considerada uma das operações mais importantes nos sistemas de produção de café devido ao seu elevado custo e ao impacto que tem na qualidade do produto. Para reduzir os custos de produção, tem-se buscado formas de mecanizar essa operação. As máquinas de colheita de café geralmente derriçam os frutos por meio de vibrações mecânicas e impacto. Portanto, o estudo do comportamento dinâmico dos sistemas fruto-pedúnculo dos frutos do cafeeiro é fundamental para o desenvolvimento de máquinas adequadas a este tipo de prática. Este trabalho foi desenvolvido com o objetivo de estudar o comportamento dinâmico de sistemas fruto-pedúnculo do cafeeiro. Para tal foi empregado um modelo tridimensional em elementos finitos baseado na teoria da elasticidade linear. Todos os programas computacionais desenvolvidos foram implementados em linguagem FORTRAN 90. A primeira parte do trabalho baseou- se no desenvolvimento e implementação do modelo de elementos finitos. As características geométricas, físicas e inerciais do sistema foram determinadas experimentalmente para a variedade Catuaí Vermelho e Mundo Novo considerando diferentes graus de maturação. Um programa computacional foi desenvolvido para a determinação das freqüências naturais e modos de vibração dos sistemas fruto-pedúnculo para ambas as variedades estudadas e para os diferentes graus de maturação considerados. Adicionalmente, foi realizado um estudo das tensões geradas no sistema fruto-pedúnculo durante o processo de vibração. Para o estudo do comportamento dinâmico do sistema, durante o procedimento de colheita, foram determinadas as tensões equivalentes de von Mises. Ambos os modelos propostos foram validados com base em metodologias específicas para cada caso. Na segunda parte do trabalho foram realizados testes experimentais em uma máquina vibradora eletromagnética, para determinar o efeito de vários fatores com relação à eficiência de derriça dos frutos do cafeeiro. Os fatores avaliados foram: a freqüência (13,33 a 26,67 Hz), amplitude (7,5 a 15,0 mm), direção de vibração (transversal ou longitudinal), grau de maturação dos frutos (verde, verdoengo, cereja e passa), número de frutos por pedúnculo (um e dois frutos) e comprimento dos ramos plagiotrópicos (5, 10 e 15 cm). Foram executados dois experimentos para as variedades Catuaí Vermelho e Mundo Novo: o primeiro com o objetivo de avaliar o efeito dos fatores de forma pontual (um e dois frutos por pedúnculo) durante o processo de vibração sob a eficiência de derriça; o segundo com o objetivo de avaliar a eficiência de derriça para os ramos com frutos cereja sob o efeito de diferentes freqüências e amplitudes de vibração. A partir da análise das características modais usando elementos finitos concluiu-se que, para a variedade Catuaí Vermelho as três primeiras freqüências naturais obtidas foram de 23,21; 57,66 e 295,69 Hz para frutos verdes, de 21,81; 53,58 e 275,81 Hz para frutos verdoengos e de 19,86; 50,37 e 254,18 Hz para frutos cerejas. Para a variedade Mundo Novo as freqüências naturais obtidas foram de 23,17; 59,87 e 300,59 Hz para frutos verdes, de 23,62; 55,63 e 292,79 Hz para frutos verdoengos e de 20,56; 49,57 e 257,44 Hz para frutos cerejas. A partir da análise de tensões foram determinados 23,75 e 13,36 MPa de tensão máxima na união entre o fruto e o pedúnculo para a variedade Catuaí Vermelho e 34,67 e 19,50 MPa para a variedade Mundo Novo nos graus de maturação verde e cereja, respectivamente, considerando uma freqüência de vibração de 26,67 Hz e uma amplitude de 15,0 mm. A partir dos resultados experimentais, verificou-se que a eficiência de derriça de frutos do cafeeiro está diretamente relacionada aos fatores freqüência e amplitude de vibração. A freqüência de 26,67 Hz apresentou uma melhor eficiência de derriça para todos os graus de maturação e variedades. As freqüências entre 23,33 e 26,67 Hz e amplitudes variando entre 12,5 e 15,0 mm tenderam a apresentar maior eficiência de derriça dos frutos cereja as variedades estudadas.Item Simulation of the dynamic behavior of the coffee fruit-stem system using finite element method(Acta Scientiarum. Technology, 2014-05-15) Santos, Fábio Lúcio; Queiroz, Daniel Marçal de; Valente, Domingos Sárvio Magalhães; Coelho, André Luiz de FreitasMechanical harvesting can be considered an important factor to reduce the costs in coffee production and to improve the quality of the final product. Coffee harvesting machinery uses mechanical vibrations to accomplish the harvesting. Therefore, the determination of the natural frequencies of the fruit-stem systems is an essential dynamic parameter for the development of mechanized harvesting system by mechanical vibrations. The objective of this study was to develop a three-dimensional finite element model to determine the natural frequencies and mode shapes of the coffee fruit-stem systems, considering different fruit ripeness. Moreover, it was carried out a theoretical study, using the finite element three-dimensional model, based on the linear theory of elasticity, for determining the generated stress in a coffee fruit-stem system, during the harvesting process by mechanical vibration. The results showed that natural frequencies decrease as the ripeness condition of the fruit increases. Counter-phase mode shape can provide better detachment efficiency considering the stress generation on coffee fruit-stem system during the harvesting by mechanical vibrations and presented a difference greater than 40 Hz between the natural frequencies of the green and ripe fruit.Item Transplantio semi-mecanizado de mudas de tomate em função da velocidade de operação(Revista Agro@mbiente On-line, 2015-01-26) Santos, Fábio Lúcio; Machado, Túlio de Almeida; Valente, Domingos Sárvio Magalhães; Fernandes, Haroldo Carlos; Cunha, João Paulo BarretoO 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.Item Vibration levels on rear and front axles of a tractor in agricultural operations(Acta Scientiarum, 2013-04-10) Villibor, Geice Paula; Santos, Fábio Lúcio; Queiroz, Daniel Marçal de; Guedes, Denis MedinaExcessive vibrations in agricultural tractors can contribute with mechanical failures and subject the operator to discomfort. This work evaluated the vibration levels on rear and front axles of an agricultural tractor working at different forward speeds and wheel drive conditions in plowing and harrowing operations. Field tests were carried out in a completely randomized design in a factorial arrangement 3 x 2 (forward travel speeds x front-wheel-assist enable or disable), with three replications. Tractor vibration was measured using two single axis accelerometers fixed above the rear and front axles. The actual forward speed of the tractor was obtained by means of ultrasonic radar and the angular velocity of the wheels was measured with magnetic transducers. The drawbar force to pull the disc harrow was obtained by a load cell. The results showed that the vibration levels observed for the plowing operation were higher than observed for the harrowing operation. When the front-wheel-assist (FWA) was enabled there was a reduction in vertical vibration levels of the tractor axles. The highest vibration levels were observed in the frequency range of 2 to 4Hz for the both soil tillage operations evaluated.