Reliability of digital mems sensors: Metrological characterization of accelerometersand microphones

The reliability of digital MEMS accelerometer and microphone sensors is investigated, on the basis of suitable calibration procedures developed at INRiM, in order to provide the metrological traceability and the proper sensitivity in the digital domain. Nowadays, digital sensing systems, based on MEMS technology, are largely used in a wide range of advanced industrial, environmental, energy and medical applications. The possibility to have many accurate, low-power consuming and low-cost sensors present undoubted advantages, in terms of costs reduction and energy saving, while maintaining high quality in the control processes, monitoring or measurements and being flexible in providing enhanced data collection, automation and operation. Nevertheless, at present, digital MEMS sensors are not always reliable to quantify with adequate accuracy the measured physical phenomena, due to the lack of metrological traceability and sensitivity parameters for digital sensors

Self-calibration of the 1 MN deadweight force standard machine at INRiM

open4noThe INRiM 1 MN deadweight force standard machine (DFSM) was installed in 1995. It adopts a binary sequence of ten weights whose combinations generate forces up to 1 MN. The advantage of this system lies in the self-calibration of its weights. The procedure is based on the comparison between two forces generated by a single weight and by a group of smaller weights, nominally equal. After 25 years, a verification of the DFSM was performed. Results are within the declared CMC limits, i.e. a relative expanded uncertainty of 2 × 10-5.openPrato, A.; Mazzoleni, F.; Facello, A.; Germak, A.Prato, A.; Mazzoleni, F.; Facello, A.; Germak, A

Atmospheric organic matter in clouds: exact masses and molecular formula identification using ultrahigh-resolution FT-ICR mass spectrometry

Clouds alter the composition of atmospheric aerosol by acting as a medium for interactions between gas- and particulate-phase substances. To determine the cloud water atmospheric organic matter (AOM) composition and study the cloud processing of aerosols, two samples of supercooled clouds were collected at the Storm Peak Laboratory near Steamboat Springs, Colorado (3220 m a.s.l.). Approximately 3000 molecular formulas were assigned to ultrahigh-resolution mass spectra of the samples after using a reversed-phase extraction procedure to isolate the AOM components from the cloud water. Nitrogen-containing compounds (CHNO compounds), sulfur-containing compounds (CHOS and CHNOS compounds) and other oxygen-containing compounds (CHO compounds) with molecular weights up to 700 Da were observed. Average oxygen-to-carbon ratios of ∼0.6 indicate a slightly more oxidized composition than most water-soluble organic carbon identified in aerosol studies, which may result from aqueous oxidation in the clouds. The AOM composition indicates significant influences from biogenic secondary organic aerosol (SOA) and residential wood combustion. We observed 60% of the cloud water CHO molecular formulas to be identical to SOA samples of α-pinene, β-pinene, d-limonene, and β-caryophyllene ozonolysis. CHNO compounds had the highest number frequency and relative abundances and are associated with residential wood combustion and NOxoxidation. Multiple nitrogen atoms in the assigned molecular formulas for the nighttime cloud sample composite were observed, indicating the significance of nitrate radical reactions on the AOM composition. Several CHOS and CHNOS compounds with reduced sulfur (in addition to the commonly observed oxidized sulfur-containing compounds) were also observed; however further investigation is needed to determine the origin of the reduced sulfur-containing compounds. Overall, the molecular composition determined using ultrahigh-resolution Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry provides an unambiguous identification of the cloud water organic anion composition in the Rocky Mountain area that could help to improve the understanding of aqueous-phase processes

Procedura di confronto tra AEP, INRIM e PTB per la taratura della macchina di taratura di forza per confronto da 5 MN del Laboratorio AEP.

During the period from March to June 2015, a comparison between the primary force standard machine of the Istituto Nazionale di Ricerca Metrologica (INRiM) in Turin and Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig (Germy) and the 5 MN calibration force machine for comparison of the accredited calibration Laboratory of AEP Transducers di Cognento (MO), has been carried out. The comparison, carried out according the calibration guide EURAMET cg-4, Version 2.0, following the Traceability Path A, has been used to perform the calibration of the calibration force machines

Dynamic calibration system for seismometers: Traceability from 0.03 Hz up to 30 Hz

Mechanical calibration and traceability of seismometers in operating conditions are still a technical challenge, since very low-frequency ranges (below 0.1 Hz) are involved, and sensors under investigation are generally heavy and bulky. Recently, within the vibration metrology field, some pioneering works proposed to evaluate the seismometers’ sensitivity by applying laboratory mechanical calibration procedures, against primary or secondary standards, according to the ISO 16063 methods. By following this path, at INRIM, it has been developed a suitable system for short period horizontal and vertical ground velocity calibration of 3-axis seismometers. The calibration system allows to directly evaluate the sensitivities of the 2 axes perpendicular to the gravity field, with respect to the horizontal ground velocity (S-waves), and to derive the sensitivity of the vertical axis, parallel to the gravity field, with respect to the vertical ground velocity (P-waves), in the frequency range between 0.03 Hz and 30 Hz

Calibration of multicomponent force and moment transducers using uniaxial force standard machines integrated with tilted plates

Traceability of multicomponent force and moment transducers (MCFMTs) is a metrological priority as stated within the document of future strategy 2017-2027 of the Consultative Committee of Mass and Related Quantities of Bureau International des Poids et Mesures (BIPM). In this paper, a calibration system using force standard machines (FSMs) integrated with tilted plates is described. The main advantage of this method is the possibility to apply force and moment components using existing uniaxial FSMs without the necessity to modify them or to develop specific ones. On the other hand, force and moment components cannot be fully independently applied. Expanded uncertainties of the applied side forces and moments are in the order of around 5%, acceptable for several industrial applications. A procedure for the calibration and the uncertainty assessment of MCFMTs is also provided. Calibration results, in terms of main and cross-talk sensitivities, of a six-components transducer are shown. This method is easily implementable and can be adopted to improve the current standard

Metrological characterization of MEMS accelerometers by LDV

Abstract In this work two calibration methodologies, able to characterize the digital sensitivity of MEMS accelerometers, are presented and compared, to identify the contributions for the evaluation of the reproducibility in the low frequency range. The methodologies are different from the point of view of test bench, test procedure and data processing method. In particular, different vibration actuators are used, a linear slide and an electro-dynamic shaker, different sensors as a reference for the calibration, piezoelectric accelerometers and a Laser Doppler Vibrometer (LDV). A group of 5 accelerometers is tested for the purpose of developing the calibration techniques and evaluate a first reproducibility estimate. The experimental results provided by the two calibration procedures show significant differences. Some elements that could explain these differences have been identified, and will be further investigated in future work

Accurate coil springs axial and transverse stiffness measurements with multicomponent testing machines

Accurate characterization of coil springs, typically in terms of axial and transverse stiffness, is crucial in many applications, in particular in automotive engineering, such as suspensions, vibration reduction, seating, exhaust valves, gear engagement controls, transmission hose, fuel panels, car trunks, and engine hoods. These measurements are usually performed in spring testing machines along the vertical axis in quasi-static conditions. However, when springs are stressed along the main vertical axis, side forces, bending and torsion moments are generated, thus have to be evaluated. For this reason, a hexapod-shaped multicomponent force and moment transducer has been recently devised, realized and integrated into standard spring testing machines capable to measure the displacement along the main and transverse axes. In this way, forces, moments and displacement components generated by the springs can be measured and axial and transverse stiffness derived. In this work, two multicomponent spring testing machines with the hexapod-shaped force and moment transducer are described and measurements on different large coil springs are presented