1,721,086 research outputs found
In-situ calibration of pollutant measuring-units by means of remotely-controlled traveling standards
No full textThe increasing diffusion of pollutant measuring units which are
installed over wide areas along with the short calibration interval of several
sensors for pollutant quantities requires new calibration infrastructures to be
developed. This paper describes an attempt to develop an innovative calibration
system which is based on traveling standards and which does not require
a unit to be removed from the measuring site during the calibration process.
The calibration system is based on a simple traveling standard, which is composed
of one or more gas cylinders with known standard gas mixtures, a cell
with standard sensors and a network-enabled contro-unit, which allows the
entire standard to be remotely exercised. A prototype of the proposed system is
described and the initial results obtained in the case of sensors reported
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
Low-Cost Instrument for Whispering Gallery Mode Thermometry up to 19 GHz
Full text linkIn this paper, a portable low-cost system for the accurate measurement of complex resonance frequencies up to 19 GHz for whispering gallery mode thermometry is presented and validated. The instrument performs vectorial transmission measurements for the determination of resonance frequencies with accuracy in the order of a few parts in in 109 over two different RF/microwave bands: 1) 800 MHz-7 GHz and 2) 13-19 GHz. The former band is suitable for quasi-spherical resonator (QSR)-based experiments, currently of great interest in different metrological applications, while the latter is expressly supported for whispering gallery thermometry. The capability of the instrument to meet the performance required for whispering gallery thermometry is first verified using an extremely stable setup based on a QSR. Afterward, the calibration of the whispering gallery thermometer composed of the developed instrument and an existing resonator is performed. The obtained results prove the suitability of the instrument to replace vector network analyzers in accurate resonance-based experiments and also its capability to enable the use of whispering gallery thermometers as transfer standards in the industrial field
A Low-Cost Instrument for the Accurate Measurement of Resonances in Microwave Cavities
No full textSince vector network analysis became available, it
demonstrated its accuracy and versatility in a variety of applications,
including the accurate measurement of resonances in
microwave cavities. Unfortunately, the high cost and bulkiness
of vector network analyzers (VNAs) set a limit to their applicability.
This paper presents and discusses the design and the
initial performance tests of a simplified instrument which may
represent a valid alternative to VNAs in those applications where
the high quality factors of a microwave resonator have to be determined
with comparable accuracy but at low cost, allowing field
portability and the embedment in a more complex measurement
system. Triggered by the recent development of quasi-spherical
microwave resonators and their successful utilization in gas
metrology, we choose the extremely precise measurement of their
eigenfrequencies as a suitable test bench to validate the specifications
and assess the performance of the proposed instrument
Cross-Talk Effects in the Uncertainty Estimation of Multiplexed Data Acquisition Systems
Full text linkThis paper deals with the analysis of multi-channel data-acquisition systems with the aim of identifying and combining the main uncertainty contributions according to the GUM framework. Particular attention has been paid towards cross-talk effect, which could be an important uncertainty contribution in multiplexed data-acquisition systems. The uncertainty analysis is described for three commercial data acquisition devices highlighting that cross-talk specifications are often not suitable for a reliable uncertainty estimation in operating conditions. For this reason, an experimental set-up has been arranged to fully characterize the inter-channel effects of the investigated devices. The obtained results have highlighted that a proper characterization of a data-acquisition system is effective in estimating the actual performance at the frequency of interest and in the operating conditions for the source resistance and the input-channel configuration. Eventually, a customized procedure has been proposed that is effective in correcting the cross-talk effects also in very severe conditions of inter-channel disturbance
Low-cost real-time motion capturing system using inertial measurement units
Full text linkHuman movement modeling - also referred to as motion-capture - is a rapidly expanding field of interest for medical rehabilitation, sports training, and entertainment. Motion capture devices are used to provide a virtual 3-dimensional reconstruction of human physical activities - employing either optical or inertial sensors. Utilizing inertial measurement units and digital signal processing techniques offers a better alternative in terms of portability and immunity to visual perturbations when compared to conventional optical solutions.
In this paper, a cable-free, low-cost motion-capture solution based on inertial measurement units with a novel approach for calibration is proposed. The goal of the proposed solution is to apply motion capture to the fields that, because of cost problems, did not take enough benefit of such technology (e.g., fitness training centers). According to this goal, the necessary requirement for the proposed system is to be low-cost. Therefore, all the considerations and all the solutions provided in this work have been done according to this main requirement
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
E-learning in instrumentation and measurement courses
No full textE-learning is the one possible evolution of traditional teaching techniques and is becoming a mature technology. Several commercial suites are available to author multimedia courses either to be distributed in physical form (e.g. on CD or DVD) or to be used on-line. However the application of these suites to the instrumentation and measurement courses and in general to courses that require students to learn the use of real devices is difficult and sometime useless. In this paper, some peculiar aspects of the instrumentation and measurement courses are discussed, focusing on the impact of e-learning techniques in laboratory activities. Practical hints coming from the authors' experience in several years of in-the-field trials are reported and discussed
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