1,721,047 research outputs found
Salts in the built environment
No full textDeze thesis presenteert een uitgebreide studie over zoutmengsels die schade veroorzaken aan steenachtige materialen, onderbouwd met analyses van 11412 monsters van 338 historische sites. De studie focust op geavanceerde ionenbalansberekeningen, cruciaal voor het begrijpen van chemische processen in natuurlijke en gebouwde omgevingen. Deze berekeningen verbeteren de interpretatie van iondata en zijn essentieel voor thermodynamische modellering, nodig voor inzicht in zoutkristallisatie. Terminologie en het gebruik van het ECOS/Runsalt model voor analyse van mengsels werden geïntroduceerd en uitgebreid behandeld, hetgeen nieuwe inzichten opleverde. Vaak voorkomende mengseltypes en hun gedrag bij veranderende relatieve vochtigheid (RV) werden in kaart gebracht. Een belangrijke bevinding was de reductie van potentiële zoutfasen van 85 naar 14, cruciaal voor het identificeren van vaak voorkomende zouten. De bevindingen werden experimenteel getoetst om thermodynamische berekeningen en de kinetiek van kristallisatie en oplossing bij verschillende RV snelheden te verifiëren. De resultaten zijn significant voor verder onderzoek en de conservatie praktijk. Deze thesis draagt bij aan het begrip van zouten gerelateerd aan steenverwering, stimuleert onderzoek en samenwerking, met focus op de complexiteit van zoutmengselgedrag en invloed op gebouwen en geologische processen
Salts in the built environment
No full textAbstract: Built heritage faces significant challenges from a rapidly changing society and climate, with salts being a primary cause of stone weathering. These salts originate from various sources, including contamination from groundwater, rainwater, atmospheric sources, biological sources, or internal material. Over time, ions are transported to the surface and deposited at the drying front, where they can crystallize into various solid forms. This crystallization causes expansion in volume and exerts pressure on the surrounding materials, leading to deterioration. Despite their significance, salt mixtures, which also play a crucial role in geomorphology, planetary research, and industrial processes, are understudied. This dissertation investigates representative ion mixtures commonly found in weathered stone materials, including sodium, potassium, magnesium, calcium, chloride, nitrate, and sulfate. Through the analysis of 11,412 drill samples from 338 historic sites showing signs of salt decay, this study enables more accurate calculations of ionic equilibrium, correct identification of salt content, and further investigation into the behavior of common salt mixtures through both modeling and experimental verification. A major challenge in analyzing these ion mixtures is interpreting the derived ion balance, which can be skewed by analytical uncertainties and the presence of undetected ions, leading to disequilibrium between anions and cations. This dissertation introduces methodological improvements in ion balance calculations, allowing for a more precise interpretation of the data. The complete dataset and the optimized charge balance calculation method were made open-source to encourage involvement from the scientific community. Furthermore, the dataset facilitated the identification of commonly occurring mixture compositions, enhancing our understanding of the ions that influence mixture behavior. Innovative analytical techniques such as Environmental Scanning Electron Microscopy, Dynamic Vapor Sorption, Raman Spectroscopy, X-ray Diffraction, and time-lapse micrographs have been employed to analyze the crystallization kinetics of salts under changing relative humidity conditions. These techniques, along with the ECOS/Runsalt model, a tool for analyzing the crystallization and dissolution behavior of salt mixtures under different climatic conditions, provided new insights into the kinetics of salt mixtures and established correlations between the rate of change of relative humidity and crystallization behaviors. This study not only validates the ECOS/Runsalt model's effectiveness but also highlights its limitations and suggests practical solutions for conservation efforts. The findings are crucial for the preservation of built heritage and understanding salt deposition and dissolution mechanisms in general
Invloed van het klimaat en remediëring van zoutbelast metselwerk = Influence du climat et traitement des maçonneries chargées en sels
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Onderzoek en preventie van vocht en zoutschade gerelateerd aan het klimaat in de crypte van de Sint-Baafskathedraal te Gent
No full textBinnen de context van een haalbaarheidsstudie werd een onderzoek uitgevoerd om het klimaat te verbeteren in de crypte van de Sint-Baafskathedraal te Gent. Door het onaangenaam klimaat in de crypte is een daling van de relatieve vochtigheid en een verhoging van de temperatuur gewenst. Wegens de huidige staat van bewaring van de twaalfde-eeuwse bouwmaterialen, zoals de delaminerende Doornikse steen, de aangetaste muren en het verlies van de vijftiende-eeuwse muurschilderingen, was het noodzakelijk om de vocht- en zoutcontaminatie te onderzoeken met betrekking tot de schadefenomenen bij veranderende klimaatomstandigheden. De resultaten wijzen op de aanwezigheid van opstijgend grondvocht en complexe zoutmengsels. Cycli van kristallisatie-hydratie-oplossing van de zoutmengsels bij veranderende luchtvochtigheid werden aan de hand van computermodellering onderzocht. De resultaten maken het mogelijk om de oorzaken van de schadefenomenen te identificeren en de risico's te bepalen bij een aanpassing van het klimaat. Naast de noodzaak van systematische monitoring werden specifieke adviezen voor de bewaring van de crypte op lange termijn voorgesteld
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