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An Efficient Key Management Technique for the Internet of Things
Open AccessArticle

Development of a Solar-Powered IoT-Based Instrument for Automatic Measurement of Water Clarity

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National Key Laboratory of Digital Control and System Engineering, Ho Chi Minh University of Technology, VNU-HCM, Ho Chi Minh City 700000, Vietnam
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Faculty of Mechanical Engineering, Ho Chi Minh University of Technology, VNU-HCM, Ho Chi Minh City 700000, Vietnam
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Faculty of Electrical and Electronics Engineering, Ho Chi Minh University of Technology, VNU-HCM, Ho Chi Minh City 700000, Vietnam
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Faculty of Mechanical Engineering, Nha Trang University, Khanh Hoa Province 650000, Vietnam
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Saigon Center for Development of Industrial Technology and Machinery, Ho Chi Minh City 700000, Vietnam
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Faculty of Electrical Engineering, Ba Ria-Vung Tau College of Technology, Ba Ria - Vung Tau Province 78000, Vietnam
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Division of Computational Physics, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City 700000, Vietnam
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Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City 700000, Vietnam
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Author to whom correspondence should be addressed.
Current address: Institute for Computational Science, Ton Duc Thang University, No. 19 Nguyen Huu Tho Street, Tan Phong Ward, District 7, Ho Chi Minh City 700000, Vietnam.
Sensors 2020, 20(7), 2051; https://doi.org/10.3390/s20072051
Received: 20 February 2020 / Revised: 30 March 2020 / Accepted: 2 April 2020 / Published: 6 April 2020
(This article belongs to the Special Issue Water Quality Sensors)
Water clarity is the most common indicator of water quality. The purpose of the study was to develop an instrument which can automatically measure water clarity in place of manual measurement by Secchi disk. The instrument is suspended by buoys at the water surface and uses solar energy to measure the light intensity of LED bulbs after passing through a water column; the result is then converted to Secchi depth by using a regression function. Measurement data are stored in a cloud server so that mobile users can access via an Internet connection. Three experiments were conducted to examine the instrument performance: (i) to ensure light intensity of the LED bulbs is strong enough to pass through the water column; (ii) to determine the regression relationship between the measured light intensity of the instrument and Secchi depth; and (iii) to evaluate the coefficient of variation (CV) of the measured water clarity when using our instrument and a conventional Secchi disk. Experiment results show that the measured values of light intensity are stable with the average CV = 5.25%. Moreover, although there are slight differences between the Secchi depth measured by our instrument and those measured by Secchi disk, the measurements by our instrument can efficiently replace the measurements by conventional Secchi disk, which can be affected by weather conditions as well as by human subjectivity. View Full-Text
Keywords: water clarity; automatic measurement; light; LED; Internet of Things; Secchi disk water clarity; automatic measurement; light; LED; Internet of Things; Secchi disk
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MDPI and ACS Style

Pham, T.N.; Ho, A.P.H.; Nguyen, T.V.; Nguyen, H.M.; Truong, N.H.; Huynh, N.D.; Nguyen, T.H.; Dung, L.T. Development of a Solar-Powered IoT-Based Instrument for Automatic Measurement of Water Clarity. Sensors 2020, 20, 2051.

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