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RMS voltage measuring system for precise evaluation of electric quantities

Pogliano U., Trinchera B.

Metrology and Measurement Systems

2007

Vol. 14, nr 4

555-562

This paper is about a system for the measurement of RMS voltage. One or more of these systems can be employed as components for a wide range of applications for the measurement of electrical quantities in the field of electrical metrology. The first implementation has demonstrated its functionality and the possibility to reach a stability of the AC voltage measurement in a wide frequency range with an accuracy within 10 parts in 10&sup6;, limited only by the DC voltage accuracy of the DAC employed. A second implementation, now under investigation, aims at improving the accuracy of the system for high precision measurements.

Sea surface microlayer: a field evaluation of teflon plate, glass plate and screen sampling techniques. Part 1. Thickness of microlayer samples and relation to wind speed

Falkowska L.

Oceanologia

1999

No. 41 (2)

211-221

Surface microlayer samples were collected in the open sea with the simultaneous use of three different techniques. The thinnest water layer, 10 žm on average was collected with a teflon plate (TPM), 90 žm thick samples were collected with a glass plate (GPM) and 250 žm samples with a screen (SM). The sampling was performed under variable weather conditions. The microlayer thickness was found to increase with increasing wind speed. Glass plate and screen samples were influenced by the sea state. The intensification of turbulence in the surface layer was responsible for increased advective transport of organic matter and its accumulation near the sea surface and the greater thickness of the microlayer. When the wind speed exceeded 8 ms-1 (5oB), the microlayer thickness was observed to decrease gradually. The thickness of a microlayer collected by teflon plate was found to be inversely proportional to the wind speed. The classic screen method turned out to be the most useful of the techniques examined because of its relatively short sampling time and large sample volume. This technique is also applicable in inclement weather, when mechanical samplers are useless.