1,721,116 research outputs found
Optimization of waste heat utilization in oil field development employing a transcritical Organic Rankine Cycle (ORC) for electricity generation
No full textThis study describes the low temperature waste heat exploitation during enhanced crude oil development providing a 600–900 kW continuous electric power supply under deteriorating and oscillating thermal boundary conditions. The aim of this project was to optimize the heat-to-power conversion process by maximizing the net power output employing a transcritical Organic Rankine Cycle (ORC) with R134a as working fluid. Volatile supercritical thermo-physical fluid properties demand a review of heat transfer and expansion procedures. In order to design a comprehensive and dynamic unit configuration, a flexible cycle layout with an adjustable working fluid mass flow is required. The optimization developed a positive heat exchange/pressure correlation for the net power output with reasonable cycle efficiencies of around 10% employing moderate device sizes. Changing ambient temperatures from a winter night with 10 °C to a summer day with 28 °C ambient temperature, on the US West Coast, leads to net power differences of up to 200 kW for an identical cycle configuration. Positive and negative effects result from these temperature oscillations while the heat sink temperature decreases, as does the bottom pressure. Extended available temperature and pressure differences lead to higher power outputs and cycle efficiencies. Considering higher ambient temperatures, the efficiency and power increase per heat transfer performance increase is higher than at low ambient temperatures. For this reason a “large” heat exchanger is more beneficial under warm ambient conditions than under cold ones. In addition, “large” configurations do not easily run the risk of subcritical cycle operation unlike small configurations. It is therefore important to examine the ORC machine performance over a full range of ambients. Considering a likelihood of heat source temperature degradation, an aggressive cycle design does not pay off. The selection of larger heat transfer devices almost equalizes the net power output compared to smaller ones after a heat source temperature deterioration of ∼ 6 K. Sensitivity analyses in the way presented here are an indispensable tool for achieving optimal cycle layout and operation
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
Potential of Meat Substitutes for Climate Change Mitigation and Improved Human Health in High-Income Markets
Get PDFThe global food system contributes approximately one-quarter of greenhouse gas (GHG) emissions, with these dominated by the livestock sector. The projected increase in livestock demand is likely to undermine efforts to keep global average warming below a 2°C target. A carbon tax is often proposed as the preferred demand-side mechanism for reduced meat consumption. Previous studies, however, suggest that while this could prove successful in reducing net global emissions, it may worsen nutritional standards in lowest-income nations. An alternative market mechanism which may simultaneously reduce GHG emissions and improve health at all income levels is a reduction in the price of meat substitute products (meat-free proteins with particular nutritional and aesthetic similarities to meat). Using a combined ecological and health modeling approach, we project the associated GHG savings and health benefits associated with a stepwise reduction in the price of meat substitute products. Utilizing food demand elasticities, we quantify the substitution of meat commodities across a range of social acceptability scenarios. Our results show that meat substitute products—integrated within a “flexitarian” approach (primarily vegetarian but occasionally eating meat and fish)—have a large potential for reducing GHG emissions (up to 583 MtCO2e per year) and improving nutritional outcomes (up to 52,700 premature deaths avoided per year). However, this capacity is strongly dependent on a combination of price reductions and improved social acceptability of this product group; therefore both will be essential
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
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