1,721,000 research outputs found
Experimental determination of the dynamic elastic modulus of polymeric soft materials in an extended frequency range: A supported free loading-mass method
No full textIn this paper, an experimental test method to accurately measure the complex dynamic elastic modulus of soft materials designed for anti-vibration purposes over a wide frequency range with high resolution at low uncer-tainty levels is proposed and applied to six polymeric soft materials. The proposed experimental technique, based on standardized test set-up and laser-Doppler velocimetry, is conceived to provide the uniaxial dynamic modulus of these materials on the basis of the exact solution of the Newton's second law differential equation of a free loading-mass supported by a spring-damper system and subjected to an underlying dynamic stress. After a preliminary characterization with different standard procedures, the dynamic elastic modulus and damping properties of the six materials are investigated over a frequency range of 25-1000 Hz. The overall expanded uncertainty, on average around 3 %, is determined from five repeated measurements including the instrumental uncertainty. Results are compared with the standard ones
Saturation vapour pressure measurements of refrigerant R1224yd(Z) from 274 K to 338 K
No full textA new generation of refrigerant fluids, such as hydrofluorolefines (HFOs) and hydrochlorofluorolefines (HCFOs), has been recently introduced in order to increase the availability of zero-ODP (Ozone Depletion Potential) and low-GWP (Global Warming Potential) refrigerants. Among the HCFOs, the refrigerant HCFO-1224yd(Z) captured more attention due to its very low GWP (<1), negligible ODP (0.00023), non-flammability, low toxicity, and good chemical and thermal suitability. Due to its novelty, there is still a lack of thermodynamic property data about this refrigerant including, e.g. the saturation vapour pressure measurements that have been performed only in few experimental works, one of them used to develop the first equation of state in 2017. At INRIM, saturation vapour pressure measurements of the HCFO-1224yd(Z) were carried out in the temperature range from 274 K to 338 K, improving the measurement accuracy of previously available works. The experimental approach was based on a static method where the set-up consisted of a sample cell immersed into a temperature -controlled calibration bath with millikelvin stability, connected to a precision capacitance manometer with a measurement full scale of 0.5 MPa operating at a constant temperature of 373 K. The experimental work and the measurement results are reported together with a comprehensive uncertainty budget and a comparison against measurement data available from previous works
Vapour pressure measurements of liquid heavy water in the temperature range between 256 K and 286 K
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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
Independent tuning of acoustic and mechanical properties of phantoms for biomedical applications of ultrasound
Full text linkIn this work the preparation of tissue mimicking materials (TMMs) with independently tunable acoustic and elastic properties is reported. Although a large number of hydrogel, synthetic polymer, polysaccharides or other natural based materials have been proposed and used for the realization of TMMs, both for diagnostic and therapeutic applications of ultrasounds, up to today, simulation of acoustic properties was often performed using solid particles, reducing dramatically the transparency and inevitably affecting the homogeneity and the elastic properties of the TMM. By means of concentrated salts solutions and different polysaccharides, an easy method to prepare these TMMs have been developed. This approach would lead to obtain homogenous TMMs with Young modulus ranging over 3 orders of magnitude, i.e. from 2 to 1500 kPa, with independently tunable attenuation properties. An accurate mechanical and acoustic characterization of these TMMs have been performed. Finally, by means of a preliminary trials on protein denaturation induced by a high focused ultrasound transducer in a transparent TMMs with different attenuation values, the mechanism underlying on the formation and propagation of lesion has been investigated. Obtained results suggest that this 'chemical' approach would strongly support in vitro investigations on the open issues related to diagnostic and therapeutic application of ultrasounds
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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