1,721,060 research outputs found
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
Smart District Heating: Hypothesis to Convert Existing Utility Substations
No full textNew generation of district heating had introduced the concept of smart thermal grids, consisting in the bidirectional heat exchange between network and final users. In this context, users substations represent key points for the optimal integration between district heating networks and distributed generators.
In this paper several schemes for smart users substations will be presented and the actions required to convert existing substations will be evaluated through a technical analysis
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
Optimum organic Rankine cycle design for the application in a CHP unit feeding a district heating network
Full text linkImprovement of energy conversion efficiency in prime movers has become of fundamental importance in order to respect EU 2020 targets. In this context, hybrid power plants comprising combined heat and power (CHP) prime movers integrated with the organic Rankine cycle (ORC) create interesting opportunities to additionally increase the first law efficiency and flexibility of the system. The possibility of adding supplementary electric energy production to a CHP system, by converting the prime movers' exhaust heat with an ORC, was investigated. The inclusion of the ORC allowed operating the prime movers at full‐load (thus at their maximum efficiency), regardless of the heat demand, without dissipating not required high enthalpy‐heat. Indeed, discharged heat was recovered by the ORC to produce additional electric power at high efficiency. The CHP plant in its original arrangement (comprising three internal combustion engines of 8.5 MW size each) was compared to a new one, involving an ORC, assuming three different layout configurations and thus different ORC off‐design working conditions at user thermal part‐load operation. Results showed that the performance of the ORC, on the year basis, strongly depended on its part‐load behavior and on its regulation limits. Indeed, the layout that allowed to produce the maximum amount of ORC electric energy per year (about 10 GWh/year) was the one that could operate for the greatest number of hours during the year, which was different from the one that exhibited the highest ORC design power. However, energetic analysis demonstrated that all the proposed solutions granted to reduce the global primary energy consumption of about 18%, and they all proved to be a good investment since they allowed to return on the investment in barely 5 years, by selling the electric energy at a minimum price equal to 70 EUR/MWh
Application of environmental performance assessment of CHP systems with local and global approaches
No full textThis paper is focused on methods to indicate the environmental impact in terms of air pollutants of CHP (Combined Heat and Power) systems. The aim is to combine the energy saving achievement with information concerning the environmental benefit, in comparison with the non-CHP scenario.Environmental impact of CHP production both on global and local scale should be taken into account. In particular, the method of the "Avoided Heat Generator" is highlighted in this study as a proper approach for CHP and is used for a local-scale environmental impact evaluation. This approach calculates the reduction of emission due to CHP operation, taking into account the amount of pollutant emitted by an equivalent heat generator, which provides the same thermal power of the CHP prime mover. Moreover, the recommended approach is compared in the paper with another proposed method, based on the PSI (Pollutant Saving Index) value, which is suitable to estimate the global-scale environmental impact.Numerical evaluations of the CUP environmental benefits, in terms of NOx, CO and CO2 emissions, are shown for several CHP systems with different technologies and electric power sizes, in order to provide a comprehensive overview of current CUP prime mover environmental performance and to serve as an application reference example of the two methods potential use, in the framework of the CUP units authorization procedure. The significant effect of the reference comparative scenario is also highlighted. (C) 2014 Elsevier Ltd. All rights reserved
Smart district heating: Cogeneration and solar systems integration to convert an existing utility substation
No full textThe new goals towards efficiency increase, pollutant emissions and fossil fuel reduction had led to an increasing diffusion of district heating networks. New generations of district heating had introduced the concept of smart thermal grids, consisting in the bidirectional thermal energy exchange between network and final users and aiming at replicating the concept of electric smart grid in the heat sector. With this purpose, the integration between district heating networks and distributed generation systems becomes essential and the optimization of the utility substations is a key point. This study aims at the elaboration of possible solutions for the conversion of an existing utility substation in order to enable a bidirectional thermal energy exchange. Two different configurations will be proposed and analyzed, considering different distributed generation systems to be installed at the final user. The operation model of these cases will be defined with the purpose of optimizing the thermal exchange. Furthermore, the actions required for the conversion of the existing utility substation will be evaluated through a technical analysis, in order to define the novel substation potentialities. Based on the obtained results, the preliminary technical schematic of the converted utility substations have been designed and discussed
Application of high-temperature heat pumps in the ceramic tiles manufacturing sector for waste heat harnessing
Full text linkThe ceramic tile industry is highly energy-intensive, presenting significant opportunities for waste heat recovery.
This study investigates the use of high-temperature heat pump (HTHP) technology to enhance energy efficiency
by upgrading waste heat into process heat, reducing natural gas consumption and CO
◦
2
emissions. A compre
hensive methodology combining thermodynamic modelling, working fluid selection, and system design is
applied. An innovative waste heat recovery system leveraging HTHP technology to preheat air for the drying and
f
iring stages, recovering waste heat in two configurations, is proposed. Cyclopentane, identified as the optimal
working fluid, enables the HTHP to achieve a coefficient of performance (COP) of 2.0 while preheating air to
173
C, recovering waste heat from drying, firing, and cooling stages. In an alternative configuration recovering
heat only from drying and cooling, the HTHP reaches a COP of 2.4 with air preheated at 119
◦
C. The designed
system recovers up to 75 % of total waste heat in the first configuration, and 48 % in the second. Fuel savings are
estimated at 13.6 kg/h per tonne of tiles (18.6 % of the energy demand) and 8.89 kg/h per tonne of tiles (14.7 %)
for the two configurations, respectively, with corresponding CO
2
emission reduction of 37.5 kg/h and 24.4 kg/h
per tonne of tiles. Economic analysis confirms HTHP implementation can achieve a return on investment within
three years, aligning with current industrial HTHP costs. Results highlight HTHP technology as promising for
energy efficiency and decarbonization in ceramic tile manufacturing, supporting sustainable solutions in energy-
intensive industries
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
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