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Metrological traceability is essential to ensure the reliability of calibration tests. Calibration certificates usually include information on only one upper-level reference standard. As metrological traceability is multi-layered, generally there is no method available for end users to instantly confirm the traceability from the reference standard to a primary standard. This study focuses on the Ethereum blockchain, which has both tamper resistance and high availability, as a digital data management method. To improve the transparency and reliability of calibration tests, a smart contract that traces back to the primary standard is proposed. Consequently, it is confirmed that end users can instantly obtain traceability information. In addition, the execution of smart contracts requires transaction fees. Here, the calculation of the transaction fees is organized, and the traceability management system is discussed from a cost-effective perspective in the field of metrology.

Figure 1. Local scour at landward toe (modified from Kato et al., 2012).

In flow velocity measurements, resolution, miniaturization, and accuracy of measuring devices are important issues because the measuring devices significantly affect the flow in the micro-space, sonic flow, and turbulent flow. We studied recovery temperature anemometry (RTA) using micrometer-order thermometers and evaluated its validity in two velocity ranges (40–90 and 315–420 m/s) by conducting two experiments and a numerical simulation. The results confirmed that the difference between the reference velocity and RTA was within 5% in the velocity range 60–90 m/s for both the thermocouple and platinum thermometer given the same recovery temperature coefficient of 0.83. It is a valuable finding that velocity measurement by RTA is independent of the type of thermometer used. This suggests that the accuracy of about 5% can be guaranteed even without calibration by giving the recovery temperature coefficient according to the thermometer geometry, which is an excellent advantage not found in other anemometers. Furthermore, the supersonic flow measured using RTA agrees well with the simulation results and theoretical trends. Our findings ensure that the micrometer-order point measurement of flow velocity, which is difficult with existing anemometers, using RTA is possible over a wide range of flow velocities.