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

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

On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid

Golumbic, Lipshteyn and Stern \cite{Golumbic-epg} proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. For a nonnegative integer $k$, $B_k$-EPG graphs are defined as EPG graphs admitting a model in which each path has at most $k$ bends. Circular-arc graphs are intersection graphs of open arcs of a circle. It is easy to see that every circular-arc graph is a $B_4$-EPG graph, by embedding the circle into a rectangle of the grid. In this paper, we prove that every circular-arc graph is $B_3$-EPG, and that there exist circular-arc graphs which are not $B_2$-EPG. If we restrict ourselves to rectangular representations (i.e., the union of the paths used in the model is contained in a rectangle of the grid), we obtain EPR (edge intersection of path in a rectangle) representations. We may define $B_k$-EPR graphs, $k\geq 0$, the same way as $B_k$-EPG graphs. Circular-arc graphs are clearly $B_4$-EPR graphs and we will show that there exist circular-arc graphs that are not $B_3$-EPR graphs. We also show that normal circular-arc graphs are $B_2$-EPR graphs and that there exist normal circular-arc graphs that are not $B_1$-EPR graphs. Finally, we characterize $B_1$-EPR graphs by a family of minimal forbidden induced subgraphs, and show that they form a subclass of normal Helly circular-arc graphs

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

Mathematical modelling and numerical bifurcation analysis of inbreeding and interdisciplinarity dynamics in academia

We address a mathematical model to approximate in a coarse qualitative the interaction between inbreeding-lobbying and interdisciplinarity in academia and perform a one and two-parameter numerical bifurcation analysis to analyse its dynamics. Disciplinary diversity is a necessary condition for the development of interdisciplinarity, which is being recognized today as the key to establish a vibrant academic environment with bigger potential for breakthroughs/innovation in research and technology. However, the interaction of several factors including institutional policies, and behavioural attitudes put significant barriers on advancing interdisciplinarity. A “cognitive rigidity” may rise due to reactive academic lobby behaviours favouring inbreeding. The proposed model consists of four coupled non-linear Ordinary Differential Equations simulating the interaction between certain types of academic behaviour and the rate of knowledge advancement which is related to the level of disciplinary diversity. The effect of a control policy that inhibits inbreeding-lobbying is also investigated. The numerical bifurcation analysis reveals a rich nonlinear behaviour including multistability, sustained oscillations, limit points of limit cycles, homoclinic bifurcations as well as codimension-two bifurcations and in particular Bogdanov–Takens and Bautin bifurcations

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