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Comparison of some numerical algorithms based on augmented lagrangian regularisation for elastic-plastic analysis
No full textEngineered combinations of volcanic ash and waste glass for sustainable alkali activated materials
No full textThe environmental sustainability of new materials and production processes is of crucial importance nowadays. This study examines the use of mixtures of volcanic ash collected from street sweeping following pyroclastic eruptions of Mt. Etna, and waste glass fines derived from the recycling process of glass containers, for the manufacturing of dense blocks. These materials can be activated using a low molarity NaOH aqueous solution (3 mol/L) followed by a drying process at 75 °C for 3 days. Additionally, these same mixtures can be used for the preparation of lightweight foams through limited incorporation of sodium perborate and surfactant. The resulting solid products exhibit competitive strength-to-density ratios compared to commercial construction materials. Strength evaluations were conducted using three-point bending tests (0.47–5.93 MPa) and compression tests (7.82–22.77 MPa). Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM-EDS) reveal a complex hardening mechanism. This mechanism involves unreacted particles that are not strictly bound by gel, resulting from condensation reactions of components released in solution during alkaline attack. Regarding the cold consolidated foams, their morphology may take them suitable for application as sorbents for contaminants as well as thermal insulators (λ = 0.137 W/m·K)
Recycling Volcanic Ash and Glass Powder in the Production of Alkali Activated Materials
No full textThe environmental sustainability of new materials and production processes is of crucial importance nowadays. The mechanical properties of a new binder obtained by light activation of waste pozzolanic materials are investigated. The compound consists of volcanic ash from street sweeping after pyroclastic eruptions of Mt. Etna and waste glass fine dust from the recycling process of glass containers. A single component NaOH solution at low molarity (3M) is used. The mechanical strength is determined through of three-point bending tests and compression tests. The results of the performed basic physical and mechanical tests show that the material is promising to be used in the construction field, with compressive strength between 15 and 20 MPa
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
Double-life sustainable construction materials from alkali activation of volcanic ash/discarded glass mixture
Get PDFVolcanic ash, according to the large amount of silica and alumina, may be considered as feedstock for geopolymers. However, the relatively low reactivity, mostly due to the relatively low amount of amorphous phase, implies the introduction of ash as minor component in complex mixtures and the activation with highly concentrated alkaline solutions. This paper aims at improving the sustainability of ash conversion into inorganic polymers with adequate strength-to-density ratio, by minimizing the addition of valuable compounds and including discarded material. Fine powders of volcanic ash from Mt Etna (Italy), in fact, were activated with NaOH solutions at low molarity (3 M), with a variable water/solid ratio (0.35–0.42), after mixing with waste glass powders, from cullet purification. The adopted ash/glass proportion (50 wt%-50 wt%) was intended to favour the reuse of inorganic polymers, by firing at 950 °C, in turn causing the transformation into porous glass-ceramics with a remarkable strength-to-density ratio. A significant foaming was effectively observed, due to decomposition of hydrated alkali alumino-silicates developed upon hardening. Foams with excellent strength-to-density ratio were also obtained by thermal transformation of highly porous cold consolidated materials
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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