1,720,982 research outputs found
Low-cost Ratiometric Front-end for Industrial PRT Applications
No full textCost, size, speed, and measurement range limitations make the resistance bridge not always suitable for temperature measurements with platinum resistance thermometers (PRTs) in industrial applications. However, high-accuracy resistance thermometer systems are often needed in many industrial applications, where measurement performances comparable to resistance bridges are often needed at a lower cost and size. A tiny, portable, ratiometric front-end exploiting a 24-bit analog-to-digital converter (ADC) with Σ Δ modulator is described. It was designed to measure the resistance ratio between a 100 Ω industrial PRT (IPRT) and a reference resistor with repeatability to within a few parts in 106. Its small size makes it ideal for integration in the stem-handle assembly of a thermometric probe, enabling an early transmission of measurement data in digital form. The ADC-based system design, development, and performance testing are discussed. The system was investigated in the resistance ratio range from about 4 × 10-3 to 5 × 10-2. Furthermore, a comparison between the system performance and a commercial AC resistance bridge was carried out and the results reported in this paper. An accurate thermometer for industrial applications resulted from the above developments. The compactness of the devices enabled an implementation of the `smart sensor' concept in the measurement chain, where the front-end electronics was placed inside the IPRT handle together with an integrated memory to hold device identification, calibration coefficients, and the associated uncertainty. All data are transmitted to the readout module and are available to the user at a 5 Hz update rate for further analysis
Vapor pressure measurements over supercooled water in the temperature range from −10 1 °C to +10 −2 °C
Full text linkAn accurate measurement of saturation vapor pressure of supercooled water is a strong challenge in
metrology, mainly due to difficulties concerning keeping water at a liquid state at temperatures well
below the melting point; thus few experimental data covering limited temperature ranges (down to
about 253 K) are reported in literature. For this reason, an investigation of the water vapor – supercooled
water equilibrium along the saturation line is carried out at Istituto Nazionale di Ricerca Metrologica
(INRIM).
Measurements cover the temperature range from 261.26 K to 273.25 K, corresponding to a saturation
vapor pressure from about 244 Pa to 611 Pa. The experimental apparatus includes a borosilicate glass
sample cell, kept in a liquid bath at a constant temperature with millikelvin stability and connected to
a manifold where the pressure is measured using a capacitive diaphragm pressure gauge.
In this work, the water sample preparation, the measuring method and measurement corrections are
reported; moreover, a comparison between experimental and literature data is conducted along with
the most used vapor pressure formulations. Measurement results are discussed and uncertainty sources
estimated. The resulting expanded relative uncertainty (k = 2) varies from 0.085% at 261.26 K to 0.039% at
273.25 K
Providing measurement traceability to wireless sensor networks in museum applications
No full textThe paper presents a preliminary study performed at the Museum of the Cinema in
Torino in order to provide in situ traceability to temperature and humidity wireless sensors.
The experimental activities concerned the development of a suitable on site calibration
procedure and, subsequently, the calibrations of selected wireless sensors which
were belonging to the monitoring and AC control loop network. The work proved to be useful for a validation of the measurement probes as well as for an analysis of different approaches to provide traceability to temperature and humidity sensor networks
Development and preliminary investigation of a modular chamber for calibration of relative humidity instruments
Full text linkIn the scope of the project HUMEA – Expansion of European research capabilities
in humidity measurement within the EURAMET EMPIR program, the modular chamber for
calibration of relative humidity instruments was designed, manufactured and characterized.
The modular chamber consists of arbitrary numbers of aluminum blocks each of which
provides accommodation for the one relative humidity probe and also has the fittings for
pressure and temperature probes as well as ports for gas sampling and/or supplying. The gas
can be supplied from the dew/frost point generator or the larger climatic chamber. In the latter
case, the airflow through the chamber can be enhanced by using an additional fan. The
preliminary study was carried out to investigate the improvement in temperature uniformity
using a new chamber in combination with two climatic chambers. The investigation results
show significant improvement in temperature uniformity thus lowering the uncertainties of the
calibration of relative humidity instruments
Accurate vapor pressure measurements of supercooled water in the temperature range between 252 K and 273 K
Full text linkThe accurate knowledge of the saturation vapor pressure of liquid water and ice has a great importance in a host of applications where humidity measurements are involved since it enables the correct conversion among different physical quantities that quantify the water vapor amount of a humid gas mixture. More specifically, accurate saturation vapor pressure measurements of supercooled water are strongly required in meteorology and atmospheric sciences, especially in cloud microphysics studies. Considering the importance of this kind of measurements and the limited availability of experimental data in the literature, further measurements in the metastable region were carried out at the Istituto Nazionale di Ricerca Metrologica (INRIM). The sample cell used in the experiment is a U-shaped capillary tube made of borosilicate glass, whose temperature is kept constant by immersion in a thermostatic bath with a high temperature stability (about 1 mK). The cell is connected to a capacitive diaphragm pressure gauge measuring the equilibrium water vapor pressure, that varies between about 116 Pa at T = 252.25 K and 615 Pa at T = 273.25 K. In the present work, the measuring method and the experimental setup are described and the measurements results reported. The results obtained in the whole temperature range are compared with those available in the literature and with the commonly adopted saturation vapor pressure formulations. A complete uncertainty budget is also given, resulting in an expanded relative uncertainty ranging from 0.06% at 273.25 K to 0.20% at 252.25 K
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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