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Precise and accurate measurements are essential for reliable experimental investigations and establishments of immaculate scientific theories. It has been realized that the measurement observations are always accompanied by certain reservations, hence to provide quality measurements, systematic assessment of these uncertainties is of much significance. This article attempts to demonstrate the detailed procedure for measurement uncertainty evaluation using Monte Carlo Simulation (MCS) technique as per the recommendations of JCGM 101: 2008 using Microsoft Excel. Interestingly, it has been perceived that the expanded uncertainty values and histograms acquired using Law of Propagation of Uncertainties (LPU) and Monte Carlo Simulation (MCS) are distinctive. [ABSTRACT FROM AUTHOR]

Force transducers have prominently been utilized in numerous scientific, industrial and metrological applications since decades. They have been developed for the measurement of force in lower as well as the higher capacity to fulfil the industrial and technological requirements. Generally, a force transducer is calibrated as per standard process. For the better perceptive, there is a need of well defined calibration procedure in an organized structure according to standard ISO 376-2011. Also, factors affecting the uncertainty of measurement using law of propagation (LPU) method and their analysis have been discussed. The relative uncertainty contributions due to different factors have been explained with suitable mathematical expression. An alternative approach for evaluating uncertainty of measurement is Monte Carlo Simulation Method (MCS) that assigns probability distribution function (PDF) to input quantities and output. Efforts have been accomplished to determine uncertainty of measurement of force transducer using both methods. [ABSTRACT FROM AUTHOR]

Finite element analysis has been proved a vital factor for design studies of mechanical elements. The present paper discusses the role of finite element analysis in finding the locations of strain gauges so that the performance of the force transducers may be improved. Two ring-shaped force transducers of capacities 20 and 50 kN have been developed and the strain gauges have been placed suitably at the different locations according to the stress–strain distributions. Both force transducers have been metrologically characterized according to the calibration procedure based on standard ISO 376-2004 and IS 4169-1988 (re-affirmed 2003). The metrological results have ruled that both the force transducers have significant variations in the relative hysteresis deviations, while the differences between other factors like relative deviations because of repeatability error, reproducibility error, resolution error and zero error are not significant and thereby improve metrological properties. The results have been discussed and presented here. [ABSTRACT FROM PUBLISHER]

The complexity of electronics and hardware in Ultrasonic Interferometer Manometer (UIM) along with a large amount of health and environmental hazardous mercury compelled most of the national metrological institutes (NMIs) to replace UIM with easy to operate and handle based on low-pressure range air piston gauge (APG). Since most of the NMIs have kept APG at the top of traceability chain (only a few have functional UIM), it is an urgent need of time to understand the qualitative change in the effective area at 23 °C (A e) of piston-cylinder (p-c) assembly after long-term uses in measurement. The A e of the p-c assembly of APG has been determined using UIM over the years during six in-house comparisons, which are found in the range of 10 ppm in the pressure range 20–120 kPa, which is well within the estimated uncertainties. The quality of p-c assembly was further checked by measuring fall-rate up to the full range of APG, which provides a maximum fall rate of 2.2 mm/min at 350 kPa. The present fall rate is very close to the manufacturer reported value, which suggests long-term stability of p-c assembly after 18 years in the calibration and measurement process. The uncertainties associated with A e have been calculated using the law of propagation of uncertainty and Monte Carlo method and are found to be 9.8 ppm and 9.5 ppm at k = 2, respectively. The standard deviation of the mean of effective areas is in the range of 10−10 m2 to 10−11 m2 over 18 years, further, confirm the long-term stability of their consistency in the pressure measurement by p-c assembly. • APG shows long term stability in zero effective area. • The measurement uncertainties are within 12 ppm for the last eighteen years. • The zero pressure effective area having a standard deviation of 1.4E-10 m2. • MCM method validates LPU experimental results. • The maximum fall rate of piston obtained was 2.2 mm/min at 350 kPa. [ABSTRACT FROM AUTHOR]

The ultrasonic interferometer manometer (UIM) is an apex level primary pressure standard for Pascal realization established at National Physical Laboratory India (NPLI). The performance of UIM has been evaluated from time to time by participation in key comparisons, calibration and measurement capabilities (CMC) and publications in reputed international metrology journals. The pressure is measured using time of flight technique at 44 different frequencies in ultrasonic range and the phase measurement. The phase measurement combined with the time of flight measurement using the exact fractional algorithm provides highly accurate column length hence respective pressure values. The combined process helps in lowering the uncertainty in real experimental conditions. Recently, we have also changed UIM software from tbasic to window based program with the same algorithm which provides a column length measurement study. A detailed study was carried out for variation of fringe counts or oscillations with varying pressure. Experimental and theoretical calculation for both resolution and pressure dependent part has been carried out for uncertainties involves the physical parameters. The uncertainties in lower pressure range, i.e., between 1 Pa and 1000 Pa were varying equal or sometimes higher than the theoretical resolution value 0.0092 Pa (k = 2) because of environmental conditions like vibration, temperature, atmospheric pressure, and humidity whereas for higher pressure range, i.e., 1000 Pa to 130 kPa the uncertainties were either close or smaller than the pressure dependent theoretical uncertainty value, i.e. 7.2 × 10−6 of the reading. • We report state of art primary pressure standards with ppm level of uncertainties in measurement. • The experimental and theoretical expanded relative uncertainties at k = 2 are 5.6 ppm and 7.2 ppm, respectively. • The amplitude and wavelength of the received echo varies inversely with pressure/column of length. • Experimental as well as theoretical uncertainties are in close agreement in the range of 1 Pa–130 kPa. • The UIM shows long term stability in pressure measurement with 7.2 ppm of uncertainty since last 36 years. [ABSTRACT FROM AUTHOR]