1,720,985 research outputs found
The flexibility of virtual energy storage based on the thermal inertia of buildings in renewable energy communities: A techno-economic analysis and comparison with the electric battery solution
Full text linkThe Renewable Energy Community (REC) concept has been introduced into the European decarbonization guidelines to promote the utilization of Renewable Energy Sources (RES) and to incentivize their self-consumption at the local level. This paper analyzes the flexible use of Heat Pumps (HP) for building heating in an REC context. The Power-to-Heat (P2H) energy conversion process of HP allows the flexibility of the thermal sector to be exploited within the electricity sector: in this way, it is possible to store energy in the form of heat inside the building mass and then use the stored energy to reduce the building heating demand in the hours following the accumulation of energy. This energy storage solution has been defined as building-based Virtual Energy Storage (VES). The flexibility enabled by VES has been used to optimize the self-consumption of an REC. The flexible VES solution was evaluated, from a technical and economic point of view, through a sensitivity analysis on the variation of the RES penetration, and the results were compared with those based on a more traditional centralized electric battery (EB) storage system. The results demonstrated that the VES solution is less flexible than electric batteries. Nevertheless, both flexible solutions (VES and EB) can significantly increase the REC self-consumption: the self-consumed energy increased by between 6% and 44% thanks to the exploitation of the VES flexibility, while the EB flexibility enabled an increase in the self-consumed energy of 19% to 63% according to the scenario analyzed. However, due to the high investment cost of EB, the VES configuration resulted to be the best solution from an economic point of view
Rapid manufacturing technique used in the development of a regenerative pump impeller
No full textThis paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, from the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles using conventional milling techniques is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 axis capability. With an impeller less than 75 mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts particularly in terms of surface finish will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump
Power-to-heat plants in district heating and electricity distribution systems: A techno-economic analysis
Full text linkThis paper investigates the Power-to-Heat energy conversion process carried out by heat pumps connected to a district heating network used to provide heat to the heating sector and, at the same time, to provide flexibility for the electricity sector. The aim of this work is to analyze from a techno-economic point of view the flexibility potential of this solution used to absorb the over-generation of Variable Renewable Energy Sources in the dis-tribution system. A scenario, based on the electric distribution system and the district heating distribution system of the city of Turin, was created to carry out this type of study. The results showed that, flexible use of these Power-to-Heat systems can be exploited to shift part of electric loads in periods of renewable over-generation, with significant benefits from an economic point of view. Furthermore, the position of Power-to-Heat systems within an electricity distribution network has a significant impact; to make the most out of the flexibility of these plants, they should be placed in those areas of the network that present the greatest local over-generation of renewables. The use of heat pumps will be necessary for the energy transition thanks to the high conversion efficiency. However, in order to fully exploit all the benefit that this technology can offer its flexibility cannot be ignored
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
- …
