A correlation noise spectrometer for flicker noise measurement in graphene samples

We present a high-resolution digital correlation spectrum analyzer for the measurement of low frequency resistance fluctuations in graphene samples. The system exploits the cross-correlation method to reject the amplifiers' noise. The graphene sample is excited with a low-noise DC current. The output voltage is fed to two two-stage low-noise amplifiers connected in parallel; the DC signal component is filtered by a high-pass filter with a cutoff frequency of 34 mHz. The amplified signals are digitized by a two-channel synchronous ADC board; the cross-periodogram, which rejects uncorrelated amplifiers' noise components, is computed in real time. As a practical example, we measured the noise cross-spectrum of graphene samples in the frequency range from 0.153 Hz to 10 kHz, both in two- and four-wire configurations, and for different bias currents. We report here the measurement setup, the data analysis and the error sources

Bridges over troubled water: Incubators and start-ups’ alliances

market imperfections and lack the necessary resources to flourish. Incubators are an important policy mechanism for nurturing the creation and growth of successful entrepreneurial ventures. Specifically, we argue that in cubators act as an effective tool in filling start-ups’ social capital and in conferring them more legitimacy, so as to ease start-ups’ probability to stipulate alliances with key third parties. In this respect, we also theorize that incubators are heterogeneous and these helping functions may vary with their inherent characteristics. We propose that the supposed ‘bridging effect’ towards start-ups’ alliances could depend on the size of the incubator, its affiliation, and the type of alliance (R&D vs. commercial). The hypotheses are tested through a dataset of 1752 Italian young innovative companies. Results suggest that incubatees are significantly more likely to stipulate alliances with third parties. This bridging role is found not to depend so much on the size of the incubator; conversely, it appears highly contingent on specific matches between the institutional affiliation of the incubator and the type of alliance

L'effetto 'country of origin' sull'intenzione d'acquisto del consumatore: un'analisi metodologica

This study investigates, from the methodological perspective, how research on the influence of the country of origin effect has been conducted. To this end, the study reviews main published literature of the last five years, categorizing the documents according to various methodological issues. The growing use of the multi cue approach and the prevalent use of quantitative methods, even if based on non-probability sampling, are observed. Further, limits on the analyzed researches are pointed out. Results allow some suggestions to fill the research gaps,from the methodological point of view, and implications for future research

Primary Realization of Inductance and Capacitance Scales With a Fully Digital Bridge

This article describes an automated electronic fully digital bridge for the comparison of four-terminal-pair (4TP) impedance standards in the audio frequency range. The bridge relative accuracy, which is on the order of 10-6, makes it suitable as a reference bridge for the realization of primary scales of inductance and capacitance in metrology institutes and calibration laboratories. The performances of this bridge were validated by comparing the results of the calibrations of inductance and capacitance standards with those obtained from an existing analog reference system based on the three-voltage method. The article also reports the results of this validation

Barriers and Drivers in the Adoption of Advanced Wastewater Treatment Technologies: a Comparative Analysis of Italian Utilities

The adoption of new environmentally-friendly technologies is becoming a key issue in both public debate and policy arenas. The paper focuses on innovation adoption by wastewater utilities, and investigates why stringent environmental regulations are not sufficient to foster it. The adoption of advanced wastewater treatment technologies is made complex by the sunk nature of highly specific infrastructures, and the consequent exposure of utilities to political and institutional influences. In addition, it requires the involvement of various actors (utilities, suppliers, contractors), and is influenced by various stakeholders (communities, business users, citizens’ associations) that generally have no aligned objectives. With reference to the aforementioned theoretical background, our paper develops and analyzes a conceptual framework that unfolds over two dimensions: (a) the role played by firm-specific characteristics, i.e. technological and organizational capabilities and managerial professionalism; (b) the influence of community-level factors, i.e. citizens’ voice and pressure exerted by local stakeholders. We investigate these issues through multiple descriptive case studies based on semi-structured interviews with the CEOs and top managers of 11 wastewater utilities operating in a region in North-Italy. The results suggest that firm-specific resources could spur wastewater utilities into adopting innovation, despite an adverse institutional environment. At the same time, on the community-level side, the analysis shows that residents and local businesses are able to mobilize resources and exert pressure to either drive or hinder the adoption of water innovations

Impact of multiple radar reflectivity data assimilation on the numerical simulation of a flash flood event during the HyMeX campaign

An analysis to evaluate the impact of multiple radar reflectivity data with a three-dimensional variational (3-D-Var) assimilation system on a heavy precipitation event is presented. The main goal is to build a regionally tuned numerical prediction model and a decision-support system for environmental civil protection services and demonstrate it in the central Italian regions, distinguishing which type of observations, conventional and not (or a combination of them), is more effective in improving the accuracy of the forecasted rainfall. In that respect, during the first special observation period (SOP1) of HyMeX (Hydrological cycle in the Mediterranean Experiment) campaign several intensive observing periods (IOPs) were launched and nine of which occurred in Italy. Among them, IOP4 is chosen for this study because of its low predictability regarding the exact location and amount of precipitation. This event hit central Italy on 14 September 2012 producing heavy precipitation and causing several cases of damage to buildings, infrastructure, and roads. Reflectivity data taken from three C-band Doppler radars running operationally during the event are assimilated using the 3-D-Var technique to improve high-resolution initial conditions. In order to evaluate the impact of the assimilation procedure at different horizontal resolutions and to assess the impact of assimilating reflectivity data from multiple radars, several experiments using the Weather Research and Forecasting (WRF) model are performed. Finally, traditional verification scores such as accuracy, equitable threat score, false alarm ratio, and frequency bias - interpreted by analysing their uncertainty through bootstrap confidence intervals (CIs) - are used to objectively compare the experiments, using rain gauge data as a benchmark

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

A multi-sensor approach for volcanic ash cloud retrieval and eruption characterization: the 23 November 2013 Etna lava fountain

Volcanic activity is observed worldwide with a variety of ground and space-based remote sensing instruments, each with advantages and drawbacks. No single system can give a comprehensive description of eruptive activity, and so, a multi-sensor approach is required. This work integrates infrared and microwave volcanic ash retrievals obtained from the geostationary Meteosat Second Generation (MSG)-Spinning Enhanced Visible and Infrared Imager (SEVIRI), the polar-orbiting Aqua-MODIS and ground-based weather radar. The expected outcomes are improvements in satellite volcanic ash cloud retrieval (altitude, mass, aerosol optical depth and effective radius), the generation of new satellite products (ash concentration and particle number density in the thermal infrared) and better characterization of volcanic eruptions (plume altitude, total ash mass erupted and particle number density from thermal infrared to microwave). This approach is the core of the multi-platform volcanic ash cloud estimation procedure being developed within the European FP7-APhoRISM project. The Mt. Etna (Sicily, Italy) volcano lava fountaining event of 23 November 2013 was considered as a test case. The results of the integration show the presence of two volcanic cloud layers at different altitudes. The improvement of the volcanic ash cloud altitude leads to a mean difference between the SEVIRI ash mass estimations, before and after the integration, of about the 30%. Moreover, the percentage of the airborne “fine” ash retrieved from the satellite is estimated to be about 1%–2% of the total ash emitted during the eruption. Finally, all of the estimated parameters (volcanic ash cloud altitude, thickness and total mass) were also validated with ground-based visible camera measurements, HYSPLIT forward trajectories, Infrared Atmospheric Sounding Interferometer (IASI) satellite data and tephra deposits

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

Novel digital impedance bridges for the realization of the farad from graphene quantum standards

In the International System of Units, a realization of the impedance units is the quantum Hall effect, a macroscopic quantum phenomenon that produces quantized resistance values. Established experiments employ individual GaAs devices [1], but research is ongoing on novel materials such as graphene, which allows the realization of the units with relaxed experimental conditions. Furthermore, novel digital impedance bridges allow the implementation of simple traceability chains. In the framework of the European EMPIR project 18SIB07 GIQS (Graphene Impedance Quantum Standards), an affordable and easy-to-operate impedance standard combining novel digital impedance bridges and graphene quantum standards has been developed. An onsite comparison of an electronic and a Josephson impedance bridges developed at INRIM (Istituto Nazionale di Ricerca Metrologica, Italy) and PTB (Physikalisch-Technische Bundesanstalt, Germany), respectively, were organized for their mutual validation and to assess their performance in the realization of the farad.Measurements of temperature-controlled impedance standards and of a graphene quantized Hall resistance standard in the AC regime were performed with both INRIM’s and PTB’s bridges. The result of the comparison and the last progresses of the GIQS project are here presented