1,720,957 research outputs found
Enhancement of the hygroscopic and acoustic properties of indoor plasters with a Super Adsorbent Calcium Alginate BioPolymer
Full text linkThe present study introduces a novel-composition lime plaster that contains a Super Adsorbent BioPolymer (SABP) based on Calcium Alginate (CaAlg) for indoor applications, to improve hygrothermal and acoustic comfort. The sorption isotherm of the plaster, the moisture buffering value (MBV), the acoustic absorption, and the thermal conductivity have been assessed. The hygrothermal and acoustic properties of the modified plaster have been compared with those of the original composition to evaluate its performance under different concentrations of CaAlg (between 10 and 30% wt). Adding the CaAlg SABP to a conventional lime plaster consistently enhanced its hygroscopic properties. The results show a substantial increase in the equilibrium moisture uptake (between 10 and 23 fold) and MBV, from 0.9 to 9.3 g/(m2⋅%RH). The sound absorption coefficient improved by 0.1–0.2 at higher frequencies than 500 Hz. This paper provides detailed information on the characterization of the material. It includes details about using a dynamic vapor sorption (DVS) analyzer to evaluate the sorption isotherm and MBV. It also contains information on the impedance tube method used to measure the acoustic absorption of the material
Laboratory Assessment and In-Field Monitoring of Macro-Encapsulated Phase Change Materials for Building Envelope Applications
Full text linkPhase Change Material (PCM) based products represent an emerging technology for the building sector. For their application in the building envelope, they are usually macro-encapsulated in plastic/metal containers or placed in bags/pouches that allow an easier and safer installation. Un-fortunately, most of the product data on PCMs are obtained by means of the differential scanning calorimetry method (DSC) applied to bulk PCMs. This method, even though accurate, can lead to results that are not fully representative of the complex behavior of PCM-based products. The results of an experimental laboratory campaign, aimed at characterizing the thermal properties of a full-scale PCM product, are presented in this paper. Tests were carried out on a commercial macro-encapsulated PCM considering three different melting temperatures. The obtained results show that the overall equivalent thermal properties of the macro-encapsulated PCM products maybe some-what different from those of bulk PCMs. In a second step, two PCM products were selected and applied to a parallel roof testing room system, directly exposed to the outdoor environment. The results of the monitoring of this system have demonstrated the effectiveness of PCMs in reducing the peak heat gains through the roof components by up to 48%. Nevertheless, by comparing the laboratory results with the monitored data, it was also possible to observe that the latent heat capacity of the PCM was never fully exploited. Thus, greater benefits could be achieved in different monitoring periods, or if a PCM with a lower melting temperature were adopted
Super adsorbent bio-polymer additive to improve hygroscopic and acoustic properties of a conventional lime plaster
Full text linkThe paper introduces a new lime plaster composition, with a Super Bio-Polymeric Adsorbent (SABP), for interior applications to improve hygrothermal and acoustic comfort. Alginate SABP is added to a conventional lime plaster to improve hygroscopic and acoustic performance. The hygrothermal and acoustic properties of the modified plaster are compared with the ones of the original plaster with a preliminary moisture uptake test, the evaluation of the sorption isotherm, the moisture buffering value (MBV), and the acoustic absorption. The results show a significant increase in the equilibrium moisture contents and the MBV (from 0.7 to 6.2 g/(m2 ...%RH)). At the same time, the sound absorption coefficient is slightly improved, increasing 0.1-0.2 at frequencies higher than 500 Hz compared to the reference conventional lime plaster. The paper describes the material characterization: the sorption isotherm and the MBV are obtained using a dynamic vapor sorption (DVS) analyzer. The acoustic absorption is measured using the impedance tube method
Hygrothermal Modelling Approaches for the Moisture Buffering Behaviour of 3D-Printed Building Components with Complex Geometry
No full textIndoor humidity significantly affects building occupants’ comfort, health, and well-being. Ideally, indoor relative humidity levels should stay within 40–60% to prevent respiratory irritation and the spread of mould and viruses. Conventionally, HVAC systems are used for indoor humidity control, but they have considerable environmental impact due to both the embodied emissions in the machinery and emissions during their operation. This study explores an alternative approach using low-carbon, hygroscopic, 3D-printed panels that regulate indoor humidity passively. Two types of panels are considered: one developed by ETH Zurich using a superhygroscopic geopolymer composite with a gyroid-based geometry, and the other designed by Politecnico di Torino using a hygroscopic clay composite with a multi-layered geometry. These designs enhance moisture buffering by exposing a large surface area of the materials to indoor air. Experimental results and tentative modelling approaches are discussed, comparing simulations with measured outcomes. This work highlights the need for accurate modelling strategies for representing the hygroscopic behaviour of 3D-printed components with complex geometries, using conventional dynamic hygrothermal simulation tools
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
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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