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Wireless sensor node for surface seawater density measurements.

Baronti F, Fantechi G, Roncella R, Saletti R - Sensors (Basel) (2012)

Bottom Line: The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller.Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network.The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica, Telecomunicazioni, University of Pisa, Pisa, Italy. f.baronti@iet.unipi.it

ABSTRACT
An electronic meter to measure surface seawater density is presented. It is based on the measurement of the difference in displacements of a surface level probe and a weighted float, which according to Archimedes' law depends on the density of the water. The displacements are simultaneously measured using a high-accuracy magnetostrictive sensor, to which a custom electronic board provides a wireless connection and power supply so that it can become part of a wireless sensor network. The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller. Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network. The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

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Related in: MedlinePlus

Transient responses of the displacement readings of the two probes, when subjected in laboratory to repeated forced immersions and subsequent release. Note the hysteresis in the equilibrium points of the tripod weighted float.
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f4-sensors-12-02954: Transient responses of the displacement readings of the two probes, when subjected in laboratory to repeated forced immersions and subsequent release. Note the hysteresis in the equilibrium points of the tripod weighted float.

Mentions: First of all, the density meter was calibrated in a laboratory by comparing the measurements carried out in the distilled water tank at room temperature with the reading of a glass hydrometer for the same water sample. No compensation in temperature and sphere immersion was applied. Other experiments were then carried out to test the density meter and to characterize its behavior. Both the sea surface probe and the weighted float were forcedly immersed and then released. The displacement reading was acquired as a function of time, as reported in Figure 4, to show the dynamic response of the two probes when taken out of the equilibrium. The experiment shows repetitive damped oscillatory responses that are quite different in the two cases, particularly in terms of the time constants. The sphere is quicker in response, so that it can follow the water surface oscillations, whereas the immersed probe is slower and thus less sensitive to oscillations.


Wireless sensor node for surface seawater density measurements.

Baronti F, Fantechi G, Roncella R, Saletti R - Sensors (Basel) (2012)

Transient responses of the displacement readings of the two probes, when subjected in laboratory to repeated forced immersions and subsequent release. Note the hysteresis in the equilibrium points of the tripod weighted float.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376632&req=5

f4-sensors-12-02954: Transient responses of the displacement readings of the two probes, when subjected in laboratory to repeated forced immersions and subsequent release. Note the hysteresis in the equilibrium points of the tripod weighted float.
Mentions: First of all, the density meter was calibrated in a laboratory by comparing the measurements carried out in the distilled water tank at room temperature with the reading of a glass hydrometer for the same water sample. No compensation in temperature and sphere immersion was applied. Other experiments were then carried out to test the density meter and to characterize its behavior. Both the sea surface probe and the weighted float were forcedly immersed and then released. The displacement reading was acquired as a function of time, as reported in Figure 4, to show the dynamic response of the two probes when taken out of the equilibrium. The experiment shows repetitive damped oscillatory responses that are quite different in the two cases, particularly in terms of the time constants. The sphere is quicker in response, so that it can follow the water surface oscillations, whereas the immersed probe is slower and thus less sensitive to oscillations.

Bottom Line: The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller.Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network.The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica, Telecomunicazioni, University of Pisa, Pisa, Italy. f.baronti@iet.unipi.it

ABSTRACT
An electronic meter to measure surface seawater density is presented. It is based on the measurement of the difference in displacements of a surface level probe and a weighted float, which according to Archimedes' law depends on the density of the water. The displacements are simultaneously measured using a high-accuracy magnetostrictive sensor, to which a custom electronic board provides a wireless connection and power supply so that it can become part of a wireless sensor network. The electronics are designed so that different kinds of wireless networks can be used, by simply changing the wireless module and the relevant firmware of the microcontroller. Lastly, laboratory and at-sea tests are presented and discussed in order to highlight the functionality and the performance of a prototype of the wireless density meter node in a Bluetooth radio network. The experimental results show a good agreement of the values of the calculated density compared to reference hydrometer readings.

Show MeSH
Related in: MedlinePlus