Caveats and Recommendations to Assess the Validity and Reliability of Cycling Power Meters: A Systematic Scoping Review

A large number of power meters have become commercially available during the last decades to provide power output (PO) measurement. Some of these power meters were evaluated for validity in the literature. This study aimed to perform a review of the available literature on the validity of cycling power meters. PubMed, SPORTDiscus, and Google Scholar have been explored with PRISMA methodology. A total of 74 studies have been extracted for the reviewing process. Validity is a general quality of the measurement determined by the assessment of different metrological properties: Accuracy, sensitivity, repeatability, reproducibility, and robustness. Accuracy was most often studied from the metrological property (74 studies). Reproducibility was the second most studied (40 studies) property. Finally, repeatability, sensitivity, and robustness were considerably less studied with only 7, 5, and 5 studies, respectively. The SRM power meter is the most used as a gold standard in the studies. Moreover, the number of participants was very different among them, from 0 (when using a calibration rig) to 56 participants. The PO tested was up to 1700 W, whereas the pedalling cadence ranged between 40 and 180 rpm, including submaximal and maximal exercises. Other exercise conditions were tested, such as torque, position, temperature, and vibrations. This review provides some caveats and recommendations when testing the validity of a cycling power meter, including all of the metrological properties (accuracy, sensitivity, repeatability, reproducibility, and robustness) and some exercise conditions (PO range, sprint, pedalling cadence, torque, position, participant, temperature, vibration, and field test).

Development of Experimental Apparatus for Diaphragm Gas Meter in the Limiting Temperature Conditions

This paper presents the basic architecture and working principle of diaphragm gas meter experimental apparatus in the limiting temperature conditions. A double-standard test method with critical flow nozzle as main standard and roots flow meter as reference standard has been proposed. Indicating error and pressure loss characteristic at different temperatures are obtained by experimental research on the metrological characteristics of diaphragm gas meters (G2.5) which are produced by numerous corporations under the condition of non-reference temperature. The experimental results show that the indicating value of diaphragm gas meters under high temperatures is basically accurate, but the metrological property is a little patchy in terms of quality at low temperatures. The maximum indication error of part measuring instruments is up to 16%.

METROLOGICAL PROPERTIES OF A/D CONVERTERS UTILIZING HIGHER ORDER SIGMA–DELTA MODULATORS COMPARED WITH A/D CONVERTERS WITH MODULATORS OF FIRST ORDER

Time domain analysis is used to determine whether A/D converters that employ higher order sigma-delta modulators, widely used in digital acoustic systems, have superior performance over classical synchronous A/D converters with modulators of first order when taking into account their important metrological property which is the magnitude of the quantization error. It is shown that the quantization errors of delta-sigma A/D converters with higher order modulators are exactly on the same level as for converters with a first order modulator.