In this paper an estimation of round-trip delay (RTD) in OPC UA server-client channel was investigated in various data communication networks including Ethernet, WiFi, and 3G. Testing was carried out using the developed IoT gateway device running OPC UA server and remote computer running OPC UA client. The server and the client machines were configured to operate in Virtual Private Network powered by OpenVPN. Experimental analysis revealed that RTD values are distributed in the wide range exhibiting difficult-to-explain outliers significantly exceeding average RTD value. A preliminary exploration of the correlation between instantaneous load of communication gateway processor and RTD peaks was carried out on ARM Cortex A8 Texas instruments processors running at 600 MHz and 800 MHz clock frequency.
From analysis of used and applicable quality control systems of ceramic tiles is clearly seen that the ultrasonic measurement systems have significant advantages. Each manufactured product in this case will be evaluated and the result will be obtained with a sufficient accuracy. Therefore, one of the applicable ultrasonic measurement systems for measurement of the density of ceramic tiles is analyzed in this article. In this case, ultrasound velocity measurements were performed in the sectors with a different thickness of the 0.105 m x 0.105 m size green ceramic tile using ultrasonic transducers developed in the Ultrasound Institute of Kaunas University of Technology with different acoustic contact zones. Such approach was necessary because the thickness of the tile in these zones is quite different.
IndexTerms-Ceramic tiles, ultrasound velocity measurements, the zero-crossing and the cross-correlation technique.
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