1,720,960 research outputs found
Incorporating Recycled Plastics in Asphalt Binders and Mixtures
Full text linkPlastic has become an unavoidable material in modern life, and its existence spans from food packaging to transporting goods. Due to the low cost and durability of plastic products, the growth in plastic production has been increasing exponentially. The increased production increased plastic waste. The awareness for plastic waste management also grew due to unmanaged plastic waste and its pollution for the environment. Plastic recycling has become a significant problem worldwide due to ever-increasing plastic waste. Due to the lack of recycling, approximately 75 percent of plastic waste ended up in landfills in 2018. In the U.S., recycled plastic has been tested in different construction materials such as soil, concrete, and pavement materials to enhance the engineering properties of those materials and reduce the amount of plastic accumulating in landfills. Plastics have been tested in pavement materials as binder modifiers, binder replacement, and aggregate replacement or additive. Due to plastics' plastomeric nature, the addition of plastic makes the asphalt binder and asphalt mixture stiffer�"the incorporation of plastic shifts the performance grade temperature of asphalt binder and plastic blends towards the warmer side. The development of compatibilizers mitigated the drawbacks caused by incorporating recycled low-density polyethylene (rLDPE) in asphalt binder. Compatibilizers with polyisoprene (PI) and polybutadiene (PBD) backbones synthesized with polyethylene-block-polyethylene (glycol) (PEPEG) at two different molecular weights were tested. The effect of unreacted Maleic anhydride (MAH) in the compatibilizers was also evaluated.Polyisoprene (PI) and polybutadiene (PBD) were found effective in 1 percent and 2 percent rLDPE blends, respectively, and polybutadiene was considered an effective compatibilizer. PBD grafted with lower molecular weight PEPEG and a low level of unreacted MAH helped maintain the high-temperature performance grade while reducing the lower temperature grade of the asphalt plus 2 percent rLDPE blend
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Impact of Alternative Asphalt Binder Extenders on Asphalt Mixture Design, Production and Performance
Full text linkHistorically there has been fluctuations in asphalt binder cost and at times supply shortages. After the 1973 Oil Crisis and 2008 asphalt binder price peak, efforts to responsibly increase the amount of RAP and RAS in asphalt mixtures increased. Several alternative binders or extenders were introduced into the market following each event. Since the 2008 peak in asphalt prices and relatively high cost of asphalt binder from 2011-2015, the desire to increase RAP/RAS continued to drive alternative binder development and refinement. This has also been driven by the industries desire to continually be more sustainable. The question of whether true alternatives to petroleum based binder exists, or will exist in the near future, and can be viable has repeatedly been asked since the 2008 price peak. The asphalt industry recognized potential for price and supply instability and invested in keeping up with alternative asphalt binder and extender developments, in preparation for potential future extremes that could impact operations. There are several considerations as to how alternative asphalt binders and extenders could impact asphalt binder and mix performance, as well as production and construction operations. An extensive literature review, web-based industry stakeholder survey, and a set of 27 industry expert stakeholder interviews were conducted to answer the question, “What does an asphalt contractor need to know about potential impacts of using alternative asphalt binders and extenders?” Currently available alternative binders and the impact of them on mix design, production and construction were identified and summarized. Available alternative binders are bio-based, recycled oils or tall oil from paper manufacturing. There are alternative binders available for use in relatively low doses (≤10% of virgin binder mass) with conventional asphalt that support high binder replacement (up to 50%) mix designs when coupled with good quality virgin binders and RAP/RAS management. There will likely be changes in asphalt binder, recycling agent and mix design standards in the near future that will require producer investment in equipment and employee training and development to leverage alternative binders. Like asphalt binders, alternative binders are commodities susceptible to market conditions
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Evaluation of Cracking Behavior of Cold In-Place Recycling Asphalt Mixtures
Full text linkDuring the last decades, the asphalt pavement industry has been looking for innovative ways to make its products more environmentally friendly, and recycling methodologies have become widely accepted. According to the National Asphalt Pavement Association, during 2017 construction season, more than 76.2 million tons of RAP were put to use in new pavements in the United States, saving taxpayers more than $2.2 billion. [1]Recycling of the existing deteriorated asphalt pavement offers an attractive approach from the economic and structural standpoint. However, a severely cracked asphalt pavement presents a challenge for the design engineer due to the uncertainty in its cracking behavior and its potential of reflecting the cracks through the new overlay. The Cold In-place Recycling technique has demonstrated effectiveness in delaying the problem of reflective cracking and providing strong base layer, resulting in the requirement of a thinner overlay [2] [3] [4].This study evaluated the cracking properties of CIR by means of the Overlay Tester (OT) and the Flexural Beam Fatigue Test. The results indicated that CIR materials have good (low) crack propagation rates but the required energy to initiate a crack is low as well. In addition, some flexibility was observed in the Beam Fatigue Test but a stiff-brittle behavior was predominant. The performance characteristics of the CIR materials were used in a mechanistic analysis to recommend a structural layer coefficient for CIR layer in a flexible pavement structure
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