Acurácia De Um Mini-Lisímetro De Pesagem Eletrônica De Baixo Custo

Vilela, Márcio da Silva; Filho, Fernando Rodrigues Cabral; Teixeira, Marconi Batista; Amaral, Alisson Macendo; Vellame, Lucas Melo; Soares, Frederico Antônio Loureiro

doi:10.15809/irriga.2015v1n2p158

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…The hysteresis error of 0.031 kg, representing 0.03% (ES) or 0.02 mm, is similar to those reported by Vilela et al (2015), who obtained 0.02 kg when calibrating a mini weighing lysimeter, and by Vellame et al (2012), who obtained 0.019% and 0.015% (ES). These errors were virtually the same.…”

Section: Resultssupporting

confidence: 88%

Calibration of a Weighing Lysimeter for Measuring Cocoa Evapotranspiration

et al. 2020

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Well-operated and calibrated weighing lysimeters reliably determine the water demand of agricultural crops, and the quality of the data is evaluated through the error analyses attributed to the instrument. The objective of this study was to determine performance parameters of a weighing lysimeter and to evaluate its adequacy for the direct determination of cocoa crop evapotranspiration. The lysimeter with 1.44 m2 surface, supported on four load cells installed in the experimental area of the Graduate Program in Agricultural Engineering of the Universidade Federal do Recôncavo da Bahia, was calibrated at 3:00 a.m., using known masses at intervals of 02 minutes in five cycles of addition and removal. Data were collected using a datalogger coupled to four load cells with an individual capacity of 1000 kg, programmed to perform readings every 01 second, storing the averages of 15 minutes. The lysimeter showed excellent accuracy, with r2greater than 0.99 in the correlation between the standard masses and the signal of the load cells and standard error of linear regression estimate of 0.03 mm. The combination of repeatability and hysteresis errors with an uncertainty of 0.19% showed that the load cells have accuracy of ±0.07 mm, with resolution of 0.00033 mV, and sensitivity to detect mass changes below 0.1 mm, the system is adequate for direct measurement of cocoa ETc at time intervals of less than one hour.

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Section: Resultssupporting

confidence: 88%

Calibration of a Weighing Lysimeter for Measuring Cocoa Evapotranspiration

et al. 2020

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“…The data determined by the calibration of the lysimeters exhibited linear adjustments with high determination coefficient ( Figure 4). Several extant studies also observed high coefficients of determination that reached values equal or similar to R 2 = 0.99 (Mariano et al, 2015;Vilela et al, 2015;Carvalho et al, 2013;Lima et al, 2013). Additionally, angular and linear coefficients exhibited similar values in all the lysimeters (Figure 4).…”

Section: Resultsmentioning

confidence: 93%

Construction and calibration of weighing lysimeters with an automated drainage system

Sanches

Souza

Mendonça

et al. 2017

Rev. bras. eng. agríc. ambient.

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A B S T R A C TQuantification of the drained volume is one of the difficulties involved in using weighing lysimeters. Typically, this volume is measured by accessing a moat at the base of a lysimeter. However, it is not feasible to install the moat in small devices. Thus, the aim of this study involves developing, installing, calibrating, and checking the efficiency of small weighing lysimeters with automated drainage systems to test their functionality in field conditions. Each lysimeter is composed of a round PVC water tank with a diameter of 1.22 m and a depth of 0.58 m that is placed over a metal frame with three electronic load cells with the nominal capacity of each cell corresponding to 500 kg. The drainage system is composed of a small reservoir with a volume of 10 L, a weighing structure composed of a load cell with a nominal capacity of 30 kg, and an automatic solenoid valve driven by a device coupled to a data logger that records the data from the lysimeter and from the drainage system. Two calibrations are performed for the lysimeter as well as the drainage system to obtain equations with significant correlations (R 2 > 0.9999). The drainage system was activated several times during the tests after receiving approximately 63.4 L of water from rainfall, and this in turn indicated a good performance. Construção e calibração de lisímetros de pesagem com sistema automático de drenagem R E S U M O Uma das dificuldades na utilização de lisímetros de pesagem é a quantificação do volume drenado. Usualmente, tal volume é medido por meio de um fosso de acesso em sua base, cuja instalação é inviável em lisímetros de pequenas dimensões. Assim, este trabalho objetivou desenvolver, instalar, calibrar e verificar a eficiência de lisímetros de pesagem com sistemas de drenagem automatizados testando sua funcionalidade no campo. Cada lisímetro foi composto de uma caixa d'água circular de PVC, com 1,22 m de diâmetro e profundidade de 0,58 m, montada sobre uma estrutura metálica com 3 células de carga cada uma com capacidade nominal de 500 kg. O sistema de drenagem foi formado por um pequeno reservatório com capacidade de 10 L, uma estrutura de pesagem composta por uma célula de carga com capacidade nominal de 30 kg e uma válvula solenoide acionada automaticamente por um dispositivo eletrônico acoplado a um datalogger, que registrou os dados de ambos, do lisímetro e do sistema de drenagem. Foram realizadas calibrações de dois lisímetros e sistema de drenagem, cujos resultados foram equações ajustadas com correlação significativa (R 2 > 0,9999) para ambos. Durante os testes, o sistema de drenagem foi acionado várias vezes após receber aproximadamente 63,4 L de água por precipitação, apresentando bom desempenho.

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“…Vilela et al (2015) verificou que o erro de histerese, não linearidade, repetitividade e o erro máximo absoluto oriundos no processo de calibração, não podem ser desconsiderados no processo de calibração, principalmente quando em relação aos desvios. Depois do erro máximo absoluto e o de não-linearidade os que mais influenciaram na precisão do equipamento foi a histerese seguido da repetitividade com erro médio de 3,5 e 2,8% respectivamente.…”

Section: Resultsunclassified