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Flavio Galliana, Pier Paolo Capra, Iulian Mihai
Measurement comparison between a commercial high resistance bridge and validated systems at ultra-high resistance values

At the National Institute of Metrological Research (INRIM) a comparison between the measurements of a commercial high resistance bridge and two validated high resistance methods from 100 GΩ to 1 PΩ has been performed. The systems showed satisfactory agreement except at 1 PΩ. The commercial bridge recently has been improved by means of a new software revised by the manufacturer according to the INRIM requests. This software allows the automatic calibration of the DC Voltage sources of the bridge, with a high precision DMM, taking into account these calibration results in the subsequent resistors calibrations. With the previous software version, bridge measurements at INRIM were limited at 10 TΩ Also the bridge uncertainty specifications were updated, now being more reliable with respect to their first issue.

Oleh Velychko, Irina Karpenko, Stanislav Karpenko, Tetyana Gordiyenko
Alternative Method for Evaluation of Reference Value on COOMET Key Comparison for Power

Particular interest is the question of the development and practical application of alternative methods for processing data of international comparisons. The paper is considered the alternative method for processing of international comparison results, which based on preference aggregation method. Processing of COOMET.EM-K5 key comparison data for power by the preferences aggregation method is presented. The results are compared with the traditional approach and the considered alternative method.

Damir Ilić, Ralf Behr, Jinni Lee
Stability of AC current measurements using AC-DC shunts and the AC Quantum Voltmeter

The experimental application of the AC Quantum Voltmeter, developed at PTB, for the calibration of a source (i.e. calibrator) or a meter (i.e. ammeter) at a low-frequency AC current is described in this paper. The current measurements (from 2 mA to 2 A) are based on the voltage drop generated on an AC-DC shunt and measured by the AC Quantum Voltmeter. To obtain uncertainties at A/A level (i.e. ppm - parts per million), a self-heating of the shunt and careful settings of the measurement procedure should be considered. In this experiment, a Fluke 5720A1 calibrator is used as the current source. All measurements for this research have been done at a low frequency of 31.25 Hz, which is close to 50 Hz.

Zexin Guan, Mei Yang, Wenqiang Li, Xuefeng Ma, XinyanWang, Shang Wang
Calibration Method of Bullet Speed Measuring Devices

The bullet speed measuring device is an instrument for measuring the speed of bullets, which is widely used in public security systems, judicial identification departments, gun performance research institutions, etc. For bullet speed measuring devices, speed is the most important parameter. This article provides a method for measuring the speed of a bullet speed measuring device and an analysis of the uncertainty in measurement . There are two methods to calibrate the speed: simulation method and live ammunition method. The simulation method selects a signal generator with a time base relative frequency deviation better than 5 × 10-8 for calibration, and the speed calibration range is (10 ~ 1000) m/s. The live ammunition shooting method uses a time interval measuring instrument with a time base relative frequency deviation better than 5 × 10-8, and the speed calibration range is (40 ~ 250) m/s.

Platon Sovilj, Bojan Vujicic, Dragan Pejic, Aleksandar Radonjic, Vladimir Vujicic
Stochastic Two-bit On-line Temperature Measurement with RTD Pt-100 Sensor Operating in a Nonlinear Mode

The paper proposes a method and device for on-line temperature measurement with Pt-100 sensor operating in a nonlinear mode. The sensor measures the temperature in range of 0 °C to 200 °C, whereas the measured data are processed by applying a two-bit stochastic digital measurement method. The proposal is theoretically analyzed and tested experimentally. It is shown that the accuracy of the method depends on the accuracy of the sensor. At a sampling frequency of 1 MHz, the maximum accuracy is reached in 17.5 s and is equal to 0.015 % of full scale (FS). On the other hand, when the measurement time interval is 0.1 s (the shortest measurement interval), the accuracy is equal to 0.1 % of FS. Therefore, the proposed device can be used for both calibration and measurement purposes.

U. Cesaro, H.Coppier, P.Arpaia, M.Chadli, D.Gatti, M.Pezzetti
Assessment of a low-cost angle-meter based on resistance measurements

In this work, an accurate, low-cost electronic angle-meter is designed, manufactured and metrologically characterized. The idea at the basis of the proposed electronic goniometer is to transduce the mechanical rotation into the variation of an electrical quantity, namely a resistance. Then, such a variation can be easily measured through a low-cost multimeter used as an ohmmeter.
The metrological characterization of the prototype demonstrated that the proposed system can achieve an uncertainty as low as 1° with costs of an order of magnitude lower than devices currently available on the market.
In practical applications, this device can be used for the metrological characterization of heading instrumentation thanks to an isolated rotating plate on which several devices can be placed.

Jakub Svatos, Jan Belak, Jan Holub
System for Acoustic Detection

At present, acoustic detection techniques of gunshots (gunshot detection) are increasingly being used not only for military applications but also for civilian purposes. Detection, localization, and classification of gunshots employing acoustic detection is perspective alternative to visual detection, which is commonly used. In certain situations, to detect a source of a gunshot, an automatic acoustic detection system may be preferable. This paper presents a system for acoustic detection, which can detect localize and classify acoustic events such as gunshots. Tested firearms are 9 mm short gun, 6.35 mm short gun, .22 short gun, and .22 rifle gun with various subsonic and supersonic ammunition. As false alarms, sets of different impulse acoustic events like door slams, breaking glass, etc. have been used. To successfully classify the tested acoustic signals, Continuous Wavelet and Mel Frequency Transformation methods have been used for the signal processing, and the fully twolayer connected neural network has been implemented. The results show that the acoustic detector can be used for reliable gunshot detection, localization, and classification.

Andrea Zancla, Serena De Santis, Andrea Scorza, Salvatore Andrea Sciuto, Giovanni Sotgiu, Monica Orsini
A preliminary study on the importance of normalization methods in Infrared Micro-Spectroscopy for biomedical applications

Fourier transformed infrared (FT-IR) micro spectroscopy has become a reliable, non-destructive and automatic tool to analyze the chemical differences in biological samples associated with healthy or diseased states for diagnostic or biomedical research purpose. To extract useful information from the huge number of spectra usually recorded, statistical multivariate analysis is applied and careful data pretreatment to reduce or eliminate possible sources of error is necessary. In this regard, a quantitative criterion to evaluate the performance of different methods applied in the most sensitive pre-processing step, normalization, is proposed here. This could constitute a promising approach for validating the significance of chemical variations in complex samples of biomedical interest.

Giorgia Fiori, Fabio Fuiano, Federica Vurchio, Andrea Scorza, Jan Galo, Silvia Conforto, Salvatore A. Sciuto
Lowest Detectable Signal in medical PW Doppler Quality Control by means of a commercial Flow Phantom: a case study

PW Doppler Ultrasound (US) is commonly used in clinical practice for cardiovascular applications. Nowadays, the performances of a Doppler system are difficult to assess because a shared worldwide standard is lacking. This work aims at giving a contribution in the field, by defining a new index for PW Doppler Quality Control (QC) by using a commercial flow phantom, namely, the Lowest Detectable Signal in the spectrogram image, which scientific literature referred to as an index of PW Doppler sensitivity. A novel automatic algorithm for the estimation of such an index has been developed and validated through the results comparison with an observer judgement. Finally, a Monte Carlo Simulation has been carried out for the uncertainty analysis and robustness testing.

Giorgia Fiori, Fabio Fuiano, Federica Vurchio, Andrea Scorza, Maurizio Schmid, Silvia Conforto, Salvatore A. Sciuto
A preliminary study on a novel method for Depth of Penetration measurement in Ultrasound Quality Assessment

The maximum Ultrasound (US) Depth of Penetration (DoP) is one of the most important parameters related to medical US systems sensitivity. DoP is also suitable for characterizing those systems since it is usually measured in routine quality controls (QC) of ultrasound scanners. In common practice, DoP assessment is carried on visually and may be affected by various external factors, such as the operator related errors. To minimize these errors, image analysis algorithms have been proposed even if without a complete performance assessment. In the present work, a novel method for the automatic determination of DoP and its measurement uncertainty is proposed: it is based on the Signal to Noise Ratio (SNR) estimation, evaluated from a US phantom and in-air clips, and has been applied on a diagnostic system equipped with three different US probes (vector, convex and linear array) with similar general settings. The results have been compared with the outcomes of both a different automatic approach (already proposed in literature) and a standard procedure based on the scores provided by 5 independent observers. Despite a good agreement has been found among them, the novel method proposed requires both lower acquisition and computational time as well as a lower computational cost, confirming the convenience of an in-depth study on the topic in the next future.

Page 147 of 977 Results 1461 - 1470 of 9762