The appearance of modern electromagnetic field (EMF) monitoring networks, such as the Serbian EMF RATEL network, has enabled wireless observation of EMF level in various surroundings, particularly in areas where people experience increased sensitivity to EMF exposure. Such areas are residential locations, where persons can reside many hours per day, kindergartens, schools, hospitals and children’s playgrounds. They demand daily, comprehensive EMF monitoring, compliance checking with prescribed reference levels, as well as transparent dissemination of acquired results. This paper presents an analysis of EMF monitoring in sensitive areas on a case study of two kindergartens and an elementary school in the Serbian city of Novi Sad.

In this paper an algorithm for frequency and damping factor estimation of a real-valued noisy damped sinusoid is proposed. It is an extension of the three-point Interpolated Discrete Fourier Transform (3p-IpDFT) undamped sinusoid frequency estimator based on Maximum Sidelobe Decay (MSD) windows. Analytical expressions for the frequency and the damping factor estimators are provided and the related estimation errors due to the contribution of the spectral image component are derived and compensated. The accuracies of the proposed algorithm and other stateof-the-art frequency-domain based algorithms are compared to each other through computer simulations

This paper describes the results of performance evaluation of Coriolis flow meters from various manufacturers in high-pressure hydrogen actual flow using a calibration system with critical flow Venturi nozzles as a reference. The calibration system consisting of five nozzles was developed to calibrate the flowmeters by high-pressure, high-flow-rate hydrogen gas. The performance evaluation test of the Coriolis flowmeters wasconducted at maximum pressure of 70 MPa, gas temperature of 0 °C and -40 °C, and flow rate range from 0.5 kg/min to 3.0 kg/min. It was confirmed that the instrumental error of most of the DUTs tested in this paper was within ± 2.0 %, although the instrumental error tended to be slightly larger at -40 °C in the small flow rate range.

Hydrogen fuel cell technology is an important development direction of clean energy vehicles, which has the characteristics of zero pollution and renewability. As a key role in the commercial operation of hydrogen energy vehicles, the accuracy of the hydrogen filling quantity directly affects trade fairness and market promotion. The master meter method is generally used for the flow calibration of the existing compressed hydrogen dispenser, tin other words, high-precision Coriolis mass flowmeter is connected in series to the hydrogen filling pipeline on site, and the calibration is completed in the actual hydrogen filling process. In practice, it was found that compared with CNG, the compressed hydrogen filling process was added with a pre-charging and pressure maintaining procedure. If the model of the master meter and flowmeter in the compressed hydrogen filling dispenser to be calibrated are different, the repeatability of the calibration result will be poor. It is preliminarily concluded by experiments and analysis that the error is caused by the response of Coriolis mass flowmeter of different types to the single pulse flow during pre-charging and pressure maintaining procedure, which affects the repeatability of calibration of master meter method. Finally, it is suggested that the mass accumulated in the stage of the pre-charging pressure maintaining should not be included in the error calculation when the master meter method is used to calibrate compressed hydrogen dispenser.

Verifications of hydrogen refuelling stations have shown that variations in the station design and operation can greatly influence accuracy at the dispenser, and there are sources of error unrelated to the flow meter which if uncorrected make it difficult to achieve the accuracy requirements of OIML R-139. To improve dissemination of knowledge in this area, an interactive measurement uncertainty tool has been developed which allows the user to specify a range of different station configurations and filling scenarios to estimate the resulting errors at the dispenser. This is intended to serve as a basis for HRS manufacturers to improve HRS designs with respect to billing accuracy and to assist notified bodies in understanding uncertainty contributions from an HRS and the corrections required. This paper describes the initial version of the HRS uncertainty tool, explaining the inputs required from the user, the sources of measurement uncertainty considered, how the flow meter behaviour is modelled, and which calculations are implemented.