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No full textMode structure reconstruction with detected and undetected high-order photon correlations
No full textMetrological challenges for the monitoring of the partial pressure of CO2 in the marine environment
Get PDFThe observed rising levels of carbon dioxide (CO2) in atmosphere, highly caused by anthropogenic
emissions, are responsible for fundamental changes occurring also in seawater carbonate chemistry. The
oceans are absorbing more CO2 from the atmosphere, which is decreasing seawater pH and leading to the
acidification of marine waters, with important consequences for the global ecosystem. At present, the
partial pressure of CO2 (pCO2) is one of the few variables of the marine carbon cycle directly measurable in
situ. In order to achieve meaningful and significant measurement results, it is necessary to reach
uncertainties small enough to discriminate observed variations due to natural fluctuations, from those
due to real trends. In this framework, the development and validation of proper analytical methods and
measurement standards is of utmost importance.
Despite the availability of a variety of in situ sensors, currently used to monitor pCO2 in marine
environment, there are several problems to be faced, such as the differences in adopted calibration
methodologies and non-validated procedures, or the lack of metrological traceability and of operational
harmonization for field measurements. In addition, the scarcity and expensiveness of suitable reference
materials to calibrate instrumentation used for pCO2 monitoring represents an issue. A promising
approach could be the provision, on a larger scale, of appropriate reference standards in gas phase to be
used to calibrate pCO2 sensors, due to the stability of the CO2 in the gas mixtures. In addition,
intermediate-level standards and working standards, could represent a more affordable and widespread
traceability source. Concerning the analytical methods for pCO2 monitoring, Non Dispersive Infrared
(NDIR) photometry is quite used, but its application could be potentiated.
At INRiM, the Italian Metrology Institute, gaseous reference standards of CO2 at known amount fraction in
synthetic air or nitrogen are produced by the gravimetric method. In the framework of the H2020 Project
“MINKE - Metrology for Integrated Marine Management and Knowledge-Transfer Network”, feasibility
studies are ongoing to extend the use of these primary mixtures to the calibration of sensors for pCO2 in
seawater, in cooperation with the National Institute of Oceanography and Applied Geophysics (OGS). In
the present work, some preliminary results of this activity will be presented
Quantification of titanium dioxide (TiO2) anatase and rutile polymorphs in binary mixtures by Raman spectroscopy: an interlaboratory comparison
Get PDFThis article presents an interlaboratory comparison (ILC) on Raman spectroscopy as a technique for relative quantification of the two most common polymorphs of titanium dioxide (TiO2)-anatase and rutile-in binary mixtures. Some standard methods are currently employed internationally for the determination of TiO2 content in samples (ISO 591-1, ASTM D3720-90), but require extensive sample preparation, do not distinguish between the two polymorphs or are accurate only for small fractions of either polymorph. Raman spectroscopy is a well-suited characterization technique for measuring and differentiating TiO2 in a fast, non-invasive way, while requiring no particular reagent or sample preparation. Eleven international participants conducted the study under the framework of Versailles Project on Advanced Materials and Standards. The collected data was analyzed by means of partial least squares regression after spectral preprocessing. The resulting models all show discrepancies of lower than 2% from the nominal values in the quantitative analysis over the concentration range of 5%-95% mixture fractions, with many datasets showing substantial improvement margins on this figure. The results of this ILC provide validation of Raman spectroscopy as a reliable method for quantification of TiO2 phases
In materia implementation strategies of physical reservoir computing with memristive nanonetworks
Get PDFPhysical reservoir computing (RC) represents a computational framework that exploits information-processing capabilities of programmable matter, allowing the realization of energy-efficient neuromorphic hardware with fast learning and low training cost. Despite self-organized memristive networks have been demonstrated as physical reservoir able to extract relevant features from spatiotemporal input signals, multiterminal nanonetworks open the possibility for novel strategies of computing implementation. In this work, we report on implementation strategies of in materia RC with self-assembled memristive networks. Besides showing the spatiotemporal information processing capabilities of self-organized nanowire networks, we show through simulations that the emergent collective dynamics allows unconventional implementations of RC where the same electrodes can be used as both reservoir inputs and outputs. By comparing different implementation strategies on a digit recognition task, simulations show that the unconventional implementation allows a reduction of the hardware complexity without limiting computing capabilities, thus providing new insights for taking full advantage of in materia computing toward a rational design of neuromorphic systems
Hybrid Camouflaged Anticounterfeiting Token in a Paper Substrate
No full textAnticounterfeiting of goods is an urgent need both for luxury and cheap everyday life products. Their identification is usually based on overt technologies as printed codes, easy to produce but to be cloned as well. In this work, a standard QR-code printed on office paper but hidden by a plasmonic multilayer system is exploited. The covert label is then protected by a peculiar reading mechanism, which is only possible in specific illumination conditions. The overall photonic structure consisting of the metal -insulator -metal -insulator, the printed random QR code and the paper substrate results in a strong physical unclonable function (PUF) that provides a multi-level identification and authentication of goods ensuring uniqueness of nominally quasi-identical tags and resistance to tampering/cloning attacks. The proposed paper-based camouflage physical unclonable function (PC-PUF) can be easily fabricated by low cost and large area techniques paving the way for an easy integration in an industrial supply-chain as tags devoted to protect consumer merchandises
Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties
Get PDFRealization of a pulsed optically pumped Rb clock with a frequency stability below
Get PDFWe present the frequency stability performances of a vapor cell Rb clock based on the pulsed optically pumping (POP) technique. The clock has been developed in the frame of a collaboration between INRIM and Leonardo SpA, aiming to realize a space-qualified POP frequency standard. The results here reported were obtained with an engineered physics package, specifically designed for space applications, joint to laboratory-grade optics and electronics. The measured frequency stability expressed in terms of Allan deviation is 1.2 x 10(-13) at 1s and achieves the value of 6 x 10(-16) for integration times of 40000 s (drift removed). This is, to our knowledge, a record result for a vapor-cell frequency standard. In the paper, we show that in order to get this result, a careful stabilization of microwave and laser pulses is required
Traceability issues for contact probe and stylus instrument measurements
Get PDFSurface texture and form of products are important features to be examined and numerically characterised as parameters for engineering and scientific purposes. Form and surface measurement devices with contact probes and stylus are used to characterise such surfaces. Additionally, new generation Coordinate Measuring Machines (CMMs) can measure dimension and form simultaneously in scanning mode and also may employ surface roughness testers to perform measurements when the part is on the CMM machine. Use of probes for form measurements in scanning mode with a fast scanning speed might be problematic due to required high data acquisition rates, therefore the dynamic performance of the probe including the electronics of the instrument should be well calibrated. For the surface roughness devices, there is a need for new traceable standards due to a recent increase in the required measurement ranges (e.g. 1000 μm). Although there are documentation and methods for calibration of contact stylus instruments (ISO 12179; ISO 25178-701:2010 and DKD-R 4-2), there is no documentation for alternative routes or detailed investigations for calibration of reference stylus instruments used for calibration of reference standards of secondary level labs. The project, "Probe Trace"supported by the European Metrology Programme (EMPIR) has been started to respond to the above given demands. It aims to improve the scientific knowledge, instruments, methods and research capability in metrology for contact measurement probes and stylus instruments and enable calibration labs to develop new capabilities for selfprovision of traceability to the SI unit of length, the metre. Update on the project results will be given in the paper including, investigation of new traceability routes with displacement generators, software tools for use of spheres for calibration of the devices and noise reductions, and calibration of groove standards using various state of the art devices