1,720,953 research outputs found
Feasible Use Of Recycled Concrete Aggregates As Unbound Road Base Material In South Africa
Get PDFDissertationSustainability is one of the biggest challenges facing the world today. Construction and demolition waste (C&DW) has become a financial burden globally. Landfills are reaching maximum capacity earlier than expected and one of the biggest contributors to this phenomenon is C&DW. This is generated by the need for new infrastructure, refurbishment and demolition of existing infrastructure as a result of urbanisation that is sweeping through the world. New avenues have to be explored to reduce the financial costs and environmental effects instead of the old-fashioned way of hauling C&DW to landfills.
There is uncertainty with regards to defining CD&W in the world: every country has its own definition, and there is no exact amount available for the total of CD&W generated worldwide. The composition of C&DW varies based on site activity and is, usually, mainly made up of concrete. The United States alone generates about 100 million tons annually of C&DW, and roughly more than 50% of the landfill volume is used for C&DW. About 5 to 8 million tons of C&DW is generated annually in South Africa, where the community is not keen to recycle and few organisations are involved in recycling.
C&DW is produced by crushing and screening of material from old infrastructure and may be produced by processing the material on site or off-site. There are mobile processing machineries available in the market which gives flexibility to production of C&DW. The material is crushed and screened for production and there is technology available to assist with the removal of detrimental substance and steel.
The recycling of C&DW is still in its early stages. Although the European Union and several American States have high expectancy in C&DW material as a commodity, it took ISO 9000 until 1996 to come up with standards for recycled material. In South Africa there are currently no local standards for C&DW and there is consequently a need to develop standards to promote the use of C&DW. The introduction of standards will give environmental value to the construction industry and eradicate financial losses, and will also assist to overcome barriers.
The South African experience regarding C&DW is not totally different to the world. The South African construction industry is not keen to recycle and uses mainly virgin aggregates from natural reserves. There are some similarities such as differences among local authorities with regards to the definition of C&DW. Most local authorities define C&DW as a waste generated through demolition, excavation and building activities. The Environmental Conservation Act, Act 73 of 1989, and the National Water Act, Act 36 of 1998 define waste as unwanted or surplus material, with potential to create pollution. The South African construction industry views the restrictive definition of waste as one of the barriers for implementation of recycling of C&DW. The C&DW in South Africa is mainly made of concrete. The concrete industry comprises cement manufacturers, aggregates producers, admixture suppliers, cement extender suppliers, precast and readymix concrete producers, structural engineers, building contractors and small-scale concrete consumers such as home builders. This use of virgin aggregates has adverse effects on the environment. It also leads to more extraction and less usage as a result of availability of resources, towering energy consumption, pollution of the environment by C02 emissions, lack of rehabilitation, ecosystem disturbance and generation of waste and neglectful disposal.
The sieve analysis and densities of C&DW obtained from returned readymix concrete aggregates for the purpose of this study indicated the material was well graded and dense, which indicated the material could easily be compacted on site. The plasticity index test indicated that the material was non-plastic, which indicated in turn that the material would not be susceptible to big volumetric changes as a result of changes in moisture content.
It was found that the optimum moisture content was on the higher side and the maximum dry density was on the lower side when compared to virgin aggregates usually used as base course material in South Africa. The high optimum moisture content was due to absorption of water by the cementitious paste from previous concrete. The lower maximum dry density was due to loss of aggregates stiffness since C&DW was subjected to secondary crushing. The California bearing ratio (CBR) for C&DW was on the lower side resulting in loss of aggregates stiffness due to secondary crushing; the results were also inconsistent as a result of different classes of concrete blended to obtain C&DW.
It was found that the UCS met COLTO requirements for C3 and C4 material and it increased as the cement content increased. Contrary to unconfined compressive strength (UCS), the indirect tensile strength (ITS) was less than that of C3 and C4 material. The ITS increased as the cement content was increased which was a positive indication that higher ITS could be achieved. The maximum dry density of stabilised C&DW increased as well and the increase may be attributed to addition of cement and cementitious properties from crushed concrete aggregates which also contributed in the hydration process.
Physical and chemical test results obtained in this study indicated that C&DW could be successfully recycled, which correlates with the literature review. European countries and Japan have successfully recycled C&DW; ISO 9000 was established in 1996 for C&DW. South Africa has to change its perception towards C&DW and develop a local standard to be used by the industry to promote the use of C&DW
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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