1,720,980 research outputs found
Metrological characterization of the Gal-Indent and Gal-Vision measuring systems realised by LTF Spa for UME (Turkey)
No full textThe work consists in the metrological characterization of the Gal-Indent and Gal-Vision Measuring Systems realized by LFT Spa for TUBITAK-Ulusal Metroloji Enstitusu (UME), Gebze, Kocaeli (Turkey). The work described in the report was carried out by the Istituto Nazionale di Ricerca Metrologica (INRIM) (formerly Istituto di Metrologia “G. Colonnetti” of the Consiglio Nazionale delle Ricerche (IMGC-CNR)), as part of the work specified in the Annex A, rev. 2, of the Contract nr. 02/05 in date 10/02/2005 between LTF and IMGC-CNR.
Metrological characterizations consist in the direct and indirect verification of the measuring systems. In the direct verification, main parameters are verified; in the indirect verification, a comparison of the whole performances of measuring systems are verified through a comparison with INRIM Measuring Systems.
Results have been compared with technical specifications of Measuring Systems to verify the quality of LTF realization
Verification of Knoop indenters with a Vickers-addressed optical system
Full text linkISO 4545-2 and 4545-3 of Knoop hardness tests require the geometrical verification of the indenters.INRiM hardness laboratory, in cooperation with Galileo-LTF, has developed the Gal-Indent optical mea-suring system for the verification of Vickers indenters. This system can measure the vertex anglesbetween two opposite faces, the quadrilateral base angles and the pyramid axis tilt angle. Using thesemeasured quantities as inputs of a suitable geometrical model, the angles between the opposite edgesat the vertex of Knoop indenters, nominally 172.5°and 130°, and the angle between the pyramid andindenter holder axes can be verified with an expanded uncertainty of 0.05°. Comparison of experimentalmeasurements performed on three different Knoop indenters, previously verified by an accredited labo-ratory, shows compatible results. The proposed geometrical model could be easily implemented by lab-oratories that adopt similar measuring systems addressed for the verification of Vickers indenterswithout any modification of the experimental apparatu
Metrological characterization of the Primary Hardness Standard Machine realised by LTF for INMETRO (Brazil)
No full textThe work consists in the metrological characterization of the Primary Hardness Standard Machine (PHS Machine) realized by LFT S.p.A. (with the IMGC-CNR knowhow) for the INMETRO (Brazil). The work described in the report was carried out from August 31 to September 2, 2005 by the Istituto di Metrologia "G. Colonnetti" (IMGC) of the National Research Council (CNR) of Italy in LTF laboratory, as part of the work specified in the Annex A of the Contract nr. 02/05 in date 10/02/2005 between LTF and IMGC-CNR.
The metrological characterizations consists in the direct and indirect verification of the PHS machine; in the direct verification, the main verified parameters are the forces generated by the PHS machine and the geometry of the indenters. The indirect verification consists in the comparison of the performances of the indenters with the so called “National Indenters” and in the comparison of the hardness scales generated by the PHS machine with the national scales maintained by IMGC-CNR.
The results have been compared with the technical specifications of the PHS machine to verify the quality of the LTF construction
Absolute Measurements of the Free-Fall Acceleration g in Vesuvio, Campi Flegrei and Ischia
No full textIl lavoro descritto in seguito è stato svolto nel mese di agosto 2010 dall’Istituto Nazionale di Ricerca Metrologica (INRIM) di Torino nell’attività di cooperazione con l’Istituto Nazionale di Geofisica e Vulcanologia (INGV) – Sezione di Napoli “Osservatorio Vesuviano”.
Si riportano i risultati sperimentali delle misure assolute dell’accelerazione di caduta libera g eseguite in Vesuvio, Campi Flegrei e Ischia. Le misure sono state effettuate con il gravimetro assoluto trasportabile IMGC-02.The work hereafter described was carried out on August 2010 by the Istituto Nazionale di Ricerca Metrologica (INRIM) of Turin (Italy) in the framework of a cooperation with the Istituto Nazionale di Geofisica e Vulcanologia (INGV) – Sezione di Napoli “Osservatorio Vesuviano”.
The experimental results of absolute measurements of the free-fall acceleration g carried out in Vesuvio, Campi Flegrei and Ischia are reported. Gravity measurements were performed with the transportable absolute gravimeter IMGC 02
A new modified Jamin interferometer for the IMGC-02 transportable rise-and-fall absolute gravimeter
Full text linkThe value of the acceleration due to gravity is of interest in a wide field of physical sciences, such as metrology, geophysics and geodesy. In particular, geophysics and geodesy are mainly interested in the variations of gravity with location and time. Factors that account for the gravity changes are the earth’s rotation, departures of its surface from an equipotential spheroid, density variations that occur within the earth, geodynamical and tectonic processes. The measurements of acceleration due to gravity are performed by relative or absolute gravimeters. However, relative measurements shall be referred to the absolute ones. Absolute measurements of the acceleration due to gravity are performed by absolute gravimeters, traceable to the units of length and time through their primary standards. For this purpose, INRiM developed a transportable ballistic rise-and-fall absolute gravimeter, the IMGC-02. It uses laser interferometry to measure the symmetrical free rising and falling motion of a test mass in the gravity field. In this work the improvement of the interferometric system is described. The current interferometer is a modified Mach-Zehnder interferometer, which is equipped with a movable mirror placed above the optical prism, in order to allow the recombination of the first reference beam, which represents the fixed arm of the interferometer, with the second beam which, being reflected by the fixed upper reference corner-cube retroreflector and by the flying lower retroreflector, represents the shifting arm of the interferometer. Since the recombining beams have to be coaxial in order to avoid distortions on the laser interference fringes, the angular position of the mirror has to be adjusted every time before the measurement and has to be monitored during the measurement. The alignment is achieved by rotating the mirror around its two axis through a 2 axis piezoelectric PZT-driven tilter actuator. Unfortunately, this operation entails practical problems, is highly time-consuming and it has to be performed before and, sometimes, during the measurement session. For this reason, a new modified Jamin interferometer has been devised. Such system is similar to the modified Mach-Zehnder interferometer except that the two beams directly recombine on the optical prism, thus the movable mirror is removed. The alignment of the recombined beams is possible just shifting the reference corner-cube retroreflector along the horizontal plane. The main advantages are a simpler alignment of the two beams and a better stability in time, unless negligible Abbe errors due to the misalignment of the two upper and lower corner-cube retroreflectors, and the divergence of the retroreflectors, which is simply overcome by using corner-cubes with angular accuracy within 1”. In such way, the new interferometric system guarantees more robust measurements and a faster preliminary installation of the gravimeter before the measurement. The scheme of the new interferometer is presented
Correction of squareness measurements of Vickers indenters due to the tilt of the pyramid axis
Full text linkIn Vickers hardness measurements, ISO 6507-2 and 6507-3 Standards require to verify that the quadrilateral of the pyramid indenter base has angles of 90° ± 0.2°. Such measurement is usuallyperformed through optical measuring systems, which, rotating the diamond indenter, allowsto evaluate the angles between two consecutive faces with high accuracy. These angles correspond to the angles of the quadrilateral base when the axis of the pyramidis perfectly perpendicularto the seating surface. Nevertheless, when the pyramid axis is tilted, the angles between two consecutive faces are different from the corresponding angles on the quadrilateral base, thus a correction is required. In this work, a method to correct squareness measurements, based on a geometrical model, is presented
Absolute measurements of the free-fall acceleration in the Testi & Cini laboratory in Firenze
Full text linkThe described work was carried out on June 2016 by the Istituto Nazionale di Ricerca Metrologica (INRiM) of Turin (Italy), under the request of the Testi & Cini S.r.l., Firenze. The experimental results of the absolute measurement of the free-fall acceleration g in the Testi & Cini’s laboratory dedicated to the pressure balance calibration are reported. The measurements were performed with the transportable absolute gravimeter IMGC-02 of the INRiM.
With the IMGC-02 instrument a relative accuracy of few parts in 109 is reachable, i.e. measurement of g with uncertainty of tens microgals (1 μGal = 1 × 10−8 m s−2)
Perspectives and limits on the use of commercial low-cost digital MEMS accelerometers in gravimetry
Full text linkThe value of the acceleration due to gravity is of interest in a wide range of fields, from geophysics, geodesy, water-floor monitoring, and hazard forecasting to oil, gas and mineral exploration. For this purpose, relative or absolute gravimeters have been developed and used for decades. While absolute gravimeters are mainly used in monitoring stations or as reference, relative gravimeters are those actually used to determine the relative variations of the local gravitational field given their smaller dimension, lighter weight, and better reading resolution, despite the high costs and the difficulty in being used under severe environmental conditions. In the last years, the advent of micro-electromechanical-systems (MEMS), in particular MEMS accelerometers, has opened up the doors to new measuring possibilities at very low-costs. As a consequence, different international research groups focused their efforts to develop relative MEMS gravimeters and showed that this technology might be really useful for monitoring the gravitational field. However, their current production is limited to a few specimens and prototypes that cannot be exploited on a large scale at the present day. For this reason, this work investigates the possibilities and the limits in the use of commercial digital MEMS accelerometers as relative gravimeters. The digital MEMS accelerometers investigated in this work are two commercial low-cost digital MEMS accelerometers (STM, model LSM6DSR, and Sequoia, model GEA). The first is composed of an accelerometer sensor, a charge amplifier, and an analog-to-digital converter and is connected by a serial cable to a separated external microcontroller (ST, model 32F769IDISCOVERY), in which other electronic components are integrated. The second is composed of the sensing element and the analog-to-digital converter. Both are connected to the computer via USB cable. The two devices are included in a thermally insulated case, in which a resistive heater and a resistance thermometer (PT1000), connected in loop, are placed in order to guarantee temperature stability during use. The system, installed on a tilting table to ensure higher accuracy in the evaluation of local g, is calibrated in static conditions by comparison to the absolute gravimeter IMGC-02 at a specific measurement location at INRIM. Calibration is repeated several times over a period of a few weeks in order to evaluate repeatability, reproducibility and stability over time. Despite the promising future prospects of this technology, at present, the levels of precisions are low compared to the ones required by most of geodynamics applications
New analysis tools for the IMGC-02 absolute gravimeter: the linear model implemented via two new programs based on C++/ROOT and R softwares
Full text linkFor the modern Rise-and-Fall Absolute Gravimeters a linear model can be enabled for the processing of the trajectory described by the test body during its motion in the vacuum. Such model presents many advantages and can increase the reliability of the nal measurement.
The linear model was applied to the data taken by the INRiM IMGC-02 AG and the results were compared with the ones obtained with the non-linear one.
To implement the new model, two dedicated software tools were created. The rst one is written in C++ language and it exploits the ROOT analysis framework. The second one is created using R analysis program. Both programs are described in detail together with the correction evaluations and the data rejection criteria. The whole code is also reported in appendix
Absolute measurements of the free-fall acceleration in the Laboratoire Souterrain de Modane (LSM), France
Full text linkThe described work has been carried out on October 2013 by the Istituto Nazionale di Ricerca Metrologica (INRiM) of Turin (Italy), in collaboration with the International
Timescales with Optical Clocks (ITOC) project. The experimental results of the absolute measurement of the free-fall acceleration g in the Laboratoire Souterrain de Modane (LSM), along the Frejus tunnel between Italy and France are reported. The measurements have been performed with the transportable absolute gravimeter IMGC-02 of the INRIM in a site which will be used to install an optical clock. With this instrument a relative accuracy of few parts in 109 is reachable, i.e. measurement of g with uncertainty of tens microgals (1 μGal = 1 × 10−8 m s−2)
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