1,720,996 research outputs found
Hempcrete from cradle to grave: the role of carbonatation in the material sustainability
No full textThe goal of reducing buildings impact to the environment is achieved by minimizing the energy
consumption and through the employment of sustainable materials. However, the sustainability of
building materials is assessed too many times considering a single phase of the material lifecycle
(e.g. the use phase for good insulating materials). Even “LCA” studies focus sometimes on a single
stage of the lifecycle, but this approach is particularly wrong for materials that improve or reduce
their environmental performance during the operational phase or at the end of the building’s life.
This is the case for materials containing lime, whose strength and sustainability increase theoretically
along with the carbonatation process. An innovative building material containing lime is the
hempcrete brick: a non-structural composite material obtained from a mixture of hemp shives
(woody core of the hemp stalk) and a lime based binder; this material shows good thermal performances
( . m) and moisture buffering capacit. LCA studies about hempcrete materials
either leave out the carbonatation process from the assessment or assume that lime is fully recarbonated
in the use phase of the building. The goal of our study is to assess the real rate of
carbonatation of hempcrete bricks in order to include the results in a thorough LCA study and to
understand the weight this process can have in the overall sustainability of the material. The carbonatation
rate has been evaluated on bricks produced by the Italian company Equilibrium Srl. The
degree of carbonatation is evaluated through X-ray diffraction on samples extracted at regular intervals
from the brick production up to 5 months. Carbonatation depth profiles are obtained too.
Results show the importance of evaluating the behavior of a material in all the phases of the lifecycle
and could be used for future LCA studies on hempcrete materials exposed to similar conditions
Life cycle environmental benefits of a forward-thinking design phase for buildings: the case study of a temporary pavilion built for an international exhibition
No full textThe life cycle of a pavilion built for an international exhibition was investigated to understand the role that the design phase may play in the environmental sustainability of buildings. The limited life span of the structure allowed for a complete life cycle assessment (LCA) based on primary data to be undertaken, including the end of the first life. A methodology that considered an extension of the service life was applied to estimate the environmental impacts of distinct end-of-life scenarios. Results confirmed the paramount importance of the design phase in improving the life cycle sustainability of buildings. Accurate selection of materials allowed to markedly reduce the impact of the product stage (e.g. 37% fewer greenhouse gas emissions). Design for disassembly proved to be a necessary but not a sufficient condition to minimise the end-of-life impacts: design phase should not be limited to the appropriate selection of materials and components’ connections but must also foresee a second use for the structure or the materials at the end of the first life. Forecasting an after-life for the structure could reduce the life cycle burden up to 40% for several environmental impact categories. Conversely, if the second use is not predefined, the economic cost in the dismantling operation could become the priority rather than the salvaging of the components. Results of the present study may be used by future (temporary) building designers to improve the sustainability of their structure and to avoid the errors identified in the present case
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
Concrete with Organic Waste Materials as Aggregate Replacement
Get PDFThe disposal of high volumes of organic waste is a global issue. Using organic waste instead of sand as an aggregate material for concrete could reduce the strain on waste treatment processes and on the extraction of finite resources. At the same time, it could be a climate change mitigation strategy, by storing the biogenic carbon contained in the organic waste. This project investigated the viability of replacing 10% of fine aggregate in concrete with various organic waste materials, namely rice husk ash, wood ash, corncob granules, and wheat straw. The fresh concrete’s properties were studied using the slump test, and the hardened concrete’s mechanical properties were measured using the compressive strength and flexural strength tests. In this study, 14 days of curing were considered for the mechanical tests, although the 28-day mechanical strength is more generally accepted. The mechanical performances along with a life cycle assessment (LCA) comparison between the concrete with organic waste and traditional concrete were conducted. The results suggested that rice husk ash and wood ash are the most-suitable organic waste products for use as aggregate replacers considering the mechanical properties. The concrete samples incorporating wheat straw and corncob granules exhibited relatively low strength; unless advanced treatment methods are applied to enhance the concrete’s performance, the utilization of these organic wastes in concrete may be limited. The environmental impact assessment of traditional concrete shows that the main contributor to almost every impact category is the production of Portland cement. Sand production contributes only marginally to the overall impact of the concrete. In terms of life-cycle greenhouse gas (GHG) emissions, traditional concrete exhibits the lowest GWP impact per cubic meter when mechanical properties are included in the functional unit used for the comparison. Nevertheless, concrete samples with wood ash and rice husk ash partially offset their lower compressive strength with higher carbon sequestration, showing a similar GWP impact to traditional concrete. This makes them promising alternatives, especially for cases where limited compressive strengths are needed. Further investigations to improve their mechanical properties and optimize their performance are warranted
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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