1,720,959 research outputs found
Exergoeconomic comparison of a novel to a conventional small-scale power-to-ammonia cycle
No full textAmmonia is a promising carbon -free energy vector with potential applications for low carbon energy storage, transportation, power production, and fertilizer use. Small-scale renewable Power -to -Ammonia (P2A) is particularly suited for remote, agricultural areas. Employing real cost data, this work presents an exergoeconomic comparison of a novel to a conventional prototype containerized P2A system. The novel system is designed for low investment cost and is going to be tested in late 2023. Both systems have an installed 18 kWel electrolyzer capacity, yielding 1.5 kg/h of ammonia. However, the novel system has 90 000 euro lower purchased equipment costs of 400 000 euro and 1 800 euro lower operating and maintenance costs of 20 000 euro/y. The exergoeconomic analysis rightly identifies the key component in the novel design, the recycle valve, as the highest operation cost driver. However, the investment cost advantage of the valve compared to a recycle compressor in the conventional layout results in a slightly lower Levelised Cost Of Ammonia (LCOA) of 161 euro/kg for the novel compared to 173 euro/kg of the conventional cycle, making the novel layout overall cost superior. These values are well above values reported in literature of below 1 euro/kg. However, the data presented in this work refer to a research prototype application, whose costs are strongly affected by the high engineering cost and the low number of operating hours. A mass produced prototype with a higher utilization will have much lower costs
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
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
Thermoeconomic evaluation of a novel small-scale Power-to-Ammonia concept
No full textThe quest for sustainability requires all branches of the economy to become more renewable. In the energy sector, this means switching to renewable primary energy sources, such that the derived energy carriers and their end usage are renewable as well.
The molecule ammonia, consisting of one nitrogen and three hydrogen atoms, has the potential to be such a renewable energy carrier. For most of the past 100 years, ammonia has solely been regarded as a fertilizer, with the required nitrogen extracted from the air being fixed to hydrogen. Nowadays, the other purpose of ammonia emerges, i.e. the fixation of the highly volatile energy carrier hydrogen to nitrogen.
This work proposes a novel small-scale, Haber-Bosch based, Power-to-Ammonia process. Its simple design aims to produce ammonia from water and air using renewable electricity – in a low temperature and low pressure regime, under changing operating conditions, safe and cost superior to a more conventional concept. The use case of such a containerized process are remote farming areas, where farmers strive for fuel and fertilizer independency.
The four publications that make up this cumulative thesis are part of the fundamental steps of the process design workflow of the novel concept: A steady state thermodynamic and a dynamic evaluation of the concept, followed by a comparative investigation regarding exergy and exergy-costing between the novel concept and a more conventional one.
The results suggest that the novel design has the potential to deliver on its promises, namely producing ammonia at low pressure and temperature, dynamically and safe as well as exergy-cost superior to the competing conventional concept. However, the extensive critical analysis of the four publications conducted in this work also points out its weaknesses, mostly the many simplifying assumptions that had to be made for the simulations. Nevertheless, ways to eliminate these weaknesses in the future are suggested in this work as well.
However, in the end, only the still pending commissioning of the containerized concept will reveal how far the promising results of the publications are in agreement with reality
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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