1,721,088 research outputs found
A comparative cradle-to-gate life cycle assessment of three concrete mix designs
Get PDFPurpose:
The concrete industry faces challenges to create concrete mix designs that reduce negative environmental impacts but also maintain high performance. This has led to ‘greener’ cementitious materials being developed which can decrease the use of traditional Portland cement (PC). This study intended to carry out a ‘cradle-to-gate’ life cycle assessment (LCA) on concrete mix designs containing different cementitious blends.
Methods:
The aim of this study was to obtain the overall environmental impact, with a particular focus on carbon dioxide (CO2) emissions of three concrete mix designs: CEM I (100 % PC content), CEM II/B-V (65 % PC content, 35 % Fly Ash (FA) content) and CEM III/B (30 % PC content, 70 % ground granulated blast furnace slag (GGBS) content). Evaluations of the three concrete mixes were performed using ‘SimaPro 8’ LCA software. A comparative cradle-to-gate LCA of these mixes has not currently been explored and could present a new insight into improving the environmental impact of concrete with the use of secondary materials. Recommendations from this work would help the industry make key decisions about concrete mix designs.
Results and discussion:
Results show that Mix 2 (CEM II/B-V) and Mix 3 (CEM III/B) could potentially be taken forwards to improve their environmental impacts of concrete production. With respect to optimum mix design, it is strongly recommended that GGBS is selected as the addition of choice for reducing CO2 emissions. FA does still considerably improve sustainability when compared to PC, but this work proved that inclusion of GGBS environmentally optimises the mix design even further. Advantages of using GGBS include lower CO2 emissions, a substantial reduction of environmental impacts and an increased scope for sustainability due to the higher PC replacement levels that are permitted for GGBS. Due to mix designs enabling a higher contribution of GGBS additions, it would also indicate an increased positive effect regarding waste scenarios.
Conclusions and recommendations:
The main contribution of this work demonstrated that concrete can be produced without loss of performance whilst significantly reducing the negative environmental impacts incurred in its production. The results obtained from this work would help to define the available options for optimising concrete mix design. The only material variations in each mix were the different cementitious blends. So, by determining the best option, a platform to make recommendations can be established based upon cementitious materials
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
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
The effect of social skills training on oral proficiency and foreign language anxiety in Chinese language
No full textForeign language anxiety (FLA) impacts language learning and performance. At the same time, social interaction is an inevitable part of language learning, as emphasised in Vygotsky’s (1978) social learning theory. While the majority of the literature focuses on these two separate research trends, few researchers have considered the relationship among the following three variables: social competence, FLA, and language performance. In addition, there is a lack of studies examining FLA among young language minority children. Hence, this research explores the FLA of non-native Chinese speaking (NNCS) primary students in Hong Kong, and its relationship with their Chinese oral proficiency. It also aims to investigate the possible effect of their social competence on their Chinese oral proficiency and FLA by providing them with a social skills training programme.
The research comprised two studies. Study one validated the Foreign Language Classroom Anxiety Scale in the context of elementary schools in Hong Kong with 144 NNCS students. Two items of the original scale were removed after analysis of content validity and discussion by the expert panel in consideration of the ability of primary school students. Three factors were identified with exploratory factor analysis and were labelled “Fear of Negative Evaluation,” “Negative Attitudes toward the Chinese Class,” and “Low Self Confidence in Chinese.” The internal consistency of the revised scale was .908, similar to previous literature, while test-retest reliability was slightly lower (r = .789): a decreasing trend in the factor of “Fear of Negative Evaluation” by 4.55% and an increasing trend in the factor of “Low Self Confidence in Chinese” by 3.21%.
In study two, primary school grades two to four NNCS students were recruited from four schools and were divided into experimental (n = 30) and comparison (n = 20) groups. The experimental group received a 6-week multi-modal and integrated social skills training programme with emphasis on making friends and effective classroom learning. Social competence, Chinese oral proficiency, and FLA were measured at pre-test, post-test, and follow-up. Correlations were found between FLA and oral proficiency measured in individual presentations, and in one-to-one communication. The racial composition of the school was found to affect the correlations. The programme was found to be effective in improving social competence and “language structure” in one-to-one communication. No impact was found on FLA. However, in-depth analyses dividing students by their FLA level and by the racial composition in the same grade revealed different areas of improvement in oral proficiency after the training.
This study confirms the relationship between FLA and oral proficiency in young language minority children. It also supports the use of social skills training in improving their oral proficiency. Pedagogically, this study provides evidence for the combination of social and educational perspectives to assist learning Chinese as a foreign language. A social skills programme package was developed and a scale of FLA was validated to benefit NNCS students in Chinese learning over time.published_or_final_versionEducationMasterMaster of Philosoph
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