A fully digital bridge towards the realization of the farad from the quantum Hall effect

This paper presents the implementation of an electronic fully-digital impedance bridge optimized for RC comparisons with equal impedance magnitudes, together with an evaluation of the uncertainty. This bridge has been designed with the goal of realizing the farad directly from the quantum Hall effect with a bridge uncertainty component at the 1E-7 level. Thanks to its simple design, ease of operation and affordability, this bridge is suitable to be industrially manufactured. Together with the increasing availability of graphene quantum Hall resistance standards, this can provide an affordable quantum realization of the unit farad for metrology institutes and calibration centres. In this paper we present the uncertainty budget of an example measurement and the results of the validation of the bridge against a suitably modified version of the traceability chain of the Italian national standard of capacitance. The combined uncertainty of the bridge resulted from repeated measurements (overall measurement time of about 200 min) is 9.2 × 10^−8, suitable for the primary realization of the unit of capacitance from a quantized Hall resistance standard. The crosstalk among the channels of the electrical generator is the most significant uncertainty component, possibly reducible with internal shielding and filtering of the electronic generator

An international comparison of phase angle standards between the novel impedance bridges of CMI, INRIM and METAS

We report here the results of a comparison of electrical impedance standards aimed at evaluating four novel digital impedance bridges developed by the national metrology institutes CMI, INRIM and METAS. This comparison, which is the first of its kind, involved phase angle impedance standards developed by TÜBITAK UME with phase angles of  ± 30° and  ± 60°, and magnitudes ranging from about 100 Ω to 1 MΩ. The comparison demonstrated agreement among the measurement results obtained with the different bridges, and allowed us to gather information on the stability of the phase standards and on more critical aspects related to the characterization of the bridges

Inter-laboratory measurement comparison between INRIM and ESA on electrical quantities

Inter-laboratory comparisons (ILCs) are an effective mean to establish the compatibility of the measurements among laboratories. As consequence they are a mean to assure confidence in the competence and in the correctness of the dissemination processes from national Standards in different countries. This paper refers on a ILC between the National Institute of Metrological Research (INRIM-Italy) and the European space research and technology Centre (ESA- ESTEC), belonging to two different countries, on DC Voltage, DC Resistance and Electrical Capacitance carried out in 2016. The comparison showed a satisfactory agreement between the results of the two Laboratories

A coaxial cryogenic probe for quantum Hall effect measurements in the AC regime

open9sìThe quantum Hall effect is the basis for the realisation of the resistance and impedance units in the revised International System of units of 2019. This paper describes a cryogenic probe that allows to set graphene Hall devices in quantisation conditions in a helium bath (4.2 K) and magnetic fields up to 6 T, to perform precision measurements in the ac regime with impedance bridges. The probe has a full coaxial wiring, isolated from the probe structure, and holds the device in a TO-8 socket. First characterisation experiments are reported on a GaAs device which shows quantisation at 5.5 T.openMartina Marzano, Ngoc Thanh Mai Tran, Vincenzo D’Elia, Danilo Serazio, Emanuele Enrico, Massimo Ortolano, Klaus Pierz, Jan Kučera, Luca CallegaroMarzano, Martina; Thanh Mai Tran, Ngoc; D'Elia, Vincenzo; Serazio, Danilo; Enrico, Emanuele; Ortolano, Massimo; Pierz, Klaus; Kučera, Jan; Callegaro, Luc

Il progetto GIQS: Graphene Impedance Quantum Standard

The project GIQS: Graphene Impedance Quantum standard is a Joint Research Project of the European Metrology Programme for Innovation and Research (EMPIR). The goal of the project is the realisation of the SI units of electrical impedance by traceability to the quantum Hall resistance in graphene devices. The project, and the role of the Italian partners, is described

Practical Precision Electrical Impedance Measurement for the 21st Century – EMPIR Project 17RPT04 VersICal

The core objective of EMPIR project 17RPT04 VersICaL is to improve the European measurement infrastructure for electrical impedance, with particular emphasis on the capabilities of developing NMIs and calibration centres. The project will seek to exploit the results of existing research on digital impedance bridges (DIBs) by designing, constructing and validating simple, affordable versions suitable to realise the impedance scale in the range 1 nF to 10 μF and 1 mH to 10 H with relative uncertainties in the range 10-5 to 10-6. The first results of the research project, including the bridge designs and details of a polyphase digitally synthesized multichannel source capable of providing voltage outputs of precise ratio and phase are presented

Search for the optical counterpart of the GW170814 gravitational wave event with the VLT Survey Telescope

We report on the search for the optical counterpart of the gravitational event GW170814, which was carried out with the VLT Survey Telescope (VST) by the GRAvitational Wave Inaf TeAm. Observations started 17.5 h after the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo alert and we covered an area of 99 deg2 that encloses ∼ 77{{ per cent}} and ∼ 59{{ per cent}} of the initial and refined localization probability regions, respectively. A total of six epochs were secured over nearly two months. The survey reached an average limiting magnitude of 22 AB mag in the r band. After assuming the model described in Perna, Lazzati & Farr, that derives as possible optical counterpart of a BBH (binary black hole) event a transient source declining in about one day, we have computed a survey efficiency of about 5{{ per cent}}. This paper describes the VST observational strategy and the results obtained by our analysis pipelines developed to search for optical transients in multi-epoch images. We report the catalogue of the candidates with possible identifications based on light-curve fitting. We have identified two dozens of SNe, nine AGNs, and one QSO. Nineteen transients characterized by a single detection were not classified. We have restricted our analysis only to the candidates that fall into the refined localization map. None out of 39 left candidates could be positively associated with GW170814. This result implies that the possible emission of optical radiation from a BBH merger had to be fainter than r ∼ 22 (Loptical ∼ 1.4 × 1042 erg s-1) on a time interval ranging from a few hours up to two months after the gravitational wave event

Intersezioni stradali a raso in ambito urbano ed extraurbano:impiego dello schema a rotatoria. Ricerca e definizione di modelli interpretattivi della capacità nella realtà locale.

Dipartimento di Pianificazione Territoriale, Dottorato di Ricerca in Tecnologie e Pianificazione Ambientale, Ciclo XX,a.a.2007-2008Università della Calabria, Dipartimento di Pianificazione Territoriale, Dottorato di Ricerca in Tecnologie e Pianificazione Ambientale, Ciclo XX SSD ICAR/04a.a.2007-200

A resistance comparator based on a long-scale digital voltmeter

We describe a resistance comparator for resistors of equal nominal value, based on a long scale Keysight 3458A digital voltmeter. The resistors under comparison are connected in series and energized by a simple current source which includes a polarity inverter. The voltage drop ratio is measured by the 3458A set for the ratiometer function. The prototype implementation is optimized for measurements of resistors in the 10 kΩ range, including the quantum Hall effect

A simple and accurate resistance comparator with a long-scale ratiometric digital multimeter

This paper describes a resistance comparator, based on a long-scale digital multimeter, suitable for primary resistance metrology. The comparator measures the resistance ratio between two four-terminal standards from the readings of the multimeter, when operating in the voltage ratio mode. The quasi-simultaneous measurement of the resistors voltages strongly relaxes the stability requirements of the driving current source with respect to other published comparators, which are based on a shuttling voltage reading. Measurements between resistors of nominal value 12 906 Ω (the quantized Hall resistance) gree with a reference value, given by a dc current comparator bridge, within a few parts in 108