1,721,240 research outputs found
Inibitori della cristallizzazione di sali: un nuovo mezzo per prevenire il danneggiamento dei materiali lapide costituenti il patrimonio culturale
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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
"Carbon Exergy Tax (CET): Impact on Conventional Energy Systems Design and Its Contribution to Advanced Systems Utilisation",
No full textRepowering of an Existing Cogeneration Plant Including Environmental Cost Internalization
No full textCFD model for tubular SOFC stack fed directly by biomass
Full text linkThe energy transition can also be promoted by the sustainable use of biomass. Residual biomass in the Mediterranean areas can be exploited to a greater extent through highly efficient fuel cell systems. The Direct Biomass-SOFC project is based on a direct coupling between biomass power supply and SOFC tubular cells. This research project stems from the need to cover the electricity demand, avoiding the use of non-renewable sources. It will be investigated the unused or little-used biomass sources that can be exploited from the Mediterranean area. To this purpose, analyses were conducted to model a SOFC tubular cell stack by investigating the optimal configuration. The basic objective is to design a SOFC tubular cell stack, fed by syngas to produce at least 200 W. Two configurations were chosen: a square and a circular arrangement. Another objective of the study is to choose the best temperature control system. It have been selected a pressurised water system and an air system. The results show that the best performance is guaranteed by a square arrangement with an air temperature control system. The circular configuration provides less power than the square configuration, being limited by the multiple series connection to the lowest current value. The maximum electrical power produced with the square configuration is 225 W
Optimal design of PV-based grid-connected hydrogen production systems
Full text linkA cost-optimal design of power-to-hydrogen (PtH) systems is crucial to produce hydrogen at the lowest specific cost. New challenges arise when it comes to ensuring a reliable and cost-effective hydrogen supply in the presence of variable renewable energy sources. In this context, the aim of this analysis is to investigate the optimal design of PV-based grid-connected hydrogen production systems under different scenarios. To this end, an optimisation framework based on the mixed integer linear programming (MILP) technique is developed. Results are presented by employing a set of techno-economic and environmental indicators to provide general guidance on how to optimally size PtH systems, going beyond the analysis of a specific case study. The analysis is applied to Italy and particular attention is paid to exploring the impact of the price of grid electricity. The results indicate that the price of grid electricity strongly affects the optimal design of PtH systems. Specifically, in scenarios with high electricity prices, it is economically convenient to significantly oversize the PV plant and the electrolyser. The optimal PV ratio, representing the ratio between the PV size and the electrolyser size, increases from 1.6 to 2.7 as the electricity price rises from 50 to 300 euro/MWh. Additionally, when electricity prices exceed approximately 120 euro/MWh, the optimal electrolyser size (in terms of hydrogen production under rated conditions) becomes almost three times larger than the average hydrogen demand. By comparing gridconnected and off-grid scenarios, the importance of the electrical grid is also highlighted: even when poorly used, it plays a crucial role in limiting the size of the hydrogen storage. The levelised cost of hydrogen for the optimal PtH configuration falls within the range of 3.5-7 euro/kg (depending on the price of grid electricity) and increases to 8.2 euro/kg when the system operates off-grid. Finally, the hydrogen carbon footprint, quantified as kgCO2,e/kgH2, is also explored. Considering the current price and carbon intensity of grid electricity, t
"Carbon tax vs CO2 sequestration e.ects on environomic analysis of existing power plants",
No full textVariations 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
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