ESTIMATION OF WATER CONTENT, TRANSPIRATION RATE, AND WATER POTENTIAL OF COTTON FROM STEM DIAMETER MEASUREMENTS USING A LINEAR VOLTAGE DIFFERENTIAL TRANSFORMER.

Persistent Link:
http://hdl.handle.net/10150/184005
Title:
ESTIMATION OF WATER CONTENT, TRANSPIRATION RATE, AND WATER POTENTIAL OF COTTON FROM STEM DIAMETER MEASUREMENTS USING A LINEAR VOLTAGE DIFFERENTIAL TRANSFORMER.
Author:
IMANI, BEHZAD.
Issue Date:
1987
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The Linear Voltage Differential Transformer (LVDT) is an accurate sensor for stem diameter measurements. Based on the results of this dissertation it was found that stem diameter [mm] was related to water content [grams] of the cotton crop by the following equation: W(D) = 0.114(D)³ˑ¹⁸² Also the ratio of stem diameter contraction rate to the rate of water loss in cotton was experimentally determined to be: (dW/dt)/(dD/dt) = (0.166 [g min⁻¹])/(0.535 [μm min⁻¹]) = (.0469% per minute)/(.0039% per minute). Similarly the cellular water potential was derived to be a non linear function of stem diameter in cotton: ψ(t) - ψₒ = 2 ε ln (D(t)/ Dₒ) + πₒDₒ² [(1/D²(t)) – (1/Dₒ²)]. Based on this work, the grower can estimate the water content, transpiration rate and water potential of the cotton crops via stem diameter measurements. Moreover, a computer system can be implemented to remotely keep track of the water status of the field, and control the irrigation system. A general model was proposed to quantify the nature of input-output relation of the cotton crop. A proposed simplified model based on stem diameter is also introduced. The stem diameter measurements can be used as an index for estimation of cotton's water content, transpiration rate, and water potential. These three parameters and the proposed simplified model established a plant based predictive irrigation scheduling technique. The electrical output of the LVDT was quite noisy. To remove the noise and demodulate the data, two cascade circuits were designed and implemented. First, the external output circuit removed the noise and isolated the LVDT. Second, the LVDT signal conditioner demodulated the phase information from the secondary windings which were produced by the movement of the rod. By the implementation of these circuits, 1 m of the rod displacement resulted in 1.14 mv of dc voltage changes in the output.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Stems (Botany) -- Measurement.; Cotton -- Water requirements -- Measurement.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Electrical and Computer Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Gensler, W. G.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleESTIMATION OF WATER CONTENT, TRANSPIRATION RATE, AND WATER POTENTIAL OF COTTON FROM STEM DIAMETER MEASUREMENTS USING A LINEAR VOLTAGE DIFFERENTIAL TRANSFORMER.en_US
dc.creatorIMANI, BEHZAD.en_US
dc.contributor.authorIMANI, BEHZAD.en_US
dc.date.issued1987en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe Linear Voltage Differential Transformer (LVDT) is an accurate sensor for stem diameter measurements. Based on the results of this dissertation it was found that stem diameter [mm] was related to water content [grams] of the cotton crop by the following equation: W(D) = 0.114(D)³ˑ¹⁸² Also the ratio of stem diameter contraction rate to the rate of water loss in cotton was experimentally determined to be: (dW/dt)/(dD/dt) = (0.166 [g min⁻¹])/(0.535 [μm min⁻¹]) = (.0469% per minute)/(.0039% per minute). Similarly the cellular water potential was derived to be a non linear function of stem diameter in cotton: ψ(t) - ψₒ = 2 ε ln (D(t)/ Dₒ) + πₒDₒ² [(1/D²(t)) – (1/Dₒ²)]. Based on this work, the grower can estimate the water content, transpiration rate and water potential of the cotton crops via stem diameter measurements. Moreover, a computer system can be implemented to remotely keep track of the water status of the field, and control the irrigation system. A general model was proposed to quantify the nature of input-output relation of the cotton crop. A proposed simplified model based on stem diameter is also introduced. The stem diameter measurements can be used as an index for estimation of cotton's water content, transpiration rate, and water potential. These three parameters and the proposed simplified model established a plant based predictive irrigation scheduling technique. The electrical output of the LVDT was quite noisy. To remove the noise and demodulate the data, two cascade circuits were designed and implemented. First, the external output circuit removed the noise and isolated the LVDT. Second, the LVDT signal conditioner demodulated the phase information from the secondary windings which were produced by the movement of the rod. By the implementation of these circuits, 1 m of the rod displacement resulted in 1.14 mv of dc voltage changes in the output.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectStems (Botany) -- Measurement.en_US
dc.subjectCotton -- Water requirements -- Measurement.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineElectrical and Computer Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGensler, W. G.en_US
dc.identifier.proquest8709894en_US
dc.identifier.oclc698372343en_US
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