1,721,044 research outputs found
Energetic and environmental assessments about the possible use of different intake systems for desalination plants
No full textGli impianti di dissalazione hanno un impatto ambientale modesto se confrontato con quello di altri insediamenti industriali. Tuttavia, dato che essi sono situati in ambienti costieri, particolarmente fragili, maggiore attenzione dovrebbe essere dedicata a questo aspetto in fase decisionale. Oltre alle problematiche legate al rilascio di sostanze chimiche inquinanti in mare, esistono gli impatti legati alla produzione dell’energia necessaria all’impianto per funzionare e gli impatti dovuti all’impiego del suolo, alla modifica delle suolo e alla possibile interazione con le dinamiche costiere dovute alla realizzazione dell’impianto di adduzione. In questo lavoro, si vuole studiare il legame fra la tipologia di presa a mare e i suoi effetti sull’impianto, in modo da individuare le tipologie in grado di ridurre l’impatto sull’ambiente in termini di: minore invasività e tutela della costa, minori quantità di additivi chimici rilasciati a parità di produzione, minore fabbisogno energetico.Desalination plants bring about a moderate environmental impact if this is compared with that of other industrial settlements. However, since they are placed in coastal surroundings, which are very weak from in an environmental perspective, a special attention should be paid to such an aspect right in the decision-making phase. Beside the problems due to the pollutants discharged to the sea, other impacts appears on account of the generation of the energy that the desalination plant needs to work and on account of the soil use and exploitation, of the possible interaction with the coastal dynamics induced by the achievement of the intake device. In the present work the connection between the type of intake system and its effects onto the desalination plant is investigated in order to find the best solution to decrease the environmental impact in terms of: reduced tendency to spread the pollutants and coastal protection, lowered amount of chemicals which are released to the sea as the yielded water is the same, diminished energy demand
Renewable primary power source for desalination plants in coastal zones.Analysis and economical assessment in a disparching regulatory policy
No full textClimate change with its fluctuations of temperature and meteorological precipitations together with demographic pressure has made water disposal for human consumption a major problem. In coastal maritime areas desalination plant technology is one of the proposed solutions to face water needs, its economic convenience has to be evaluated when a renewable source is used as an alternative primary energy. The economical evaluation depends upon the regulatory policy governing electrical prices in the plant-hosting country. Here the focus is on the regulatory policy, on the power selling option within the deregulated market, on renewables and on the standards and rules applied in Italy, as solar and wind sources are elected as primary energy to hybrid desalination systems. A case study concerning the Asinara Island, an area with special environmental constraints, is developed. The paper analyses the desalination plant design and operation for a respectful use of the soil and a wide seasonal swing of water demand. Governance actions aiming at a more responsible use of water resources are taken into account. The recalled model is applied to analyze the integrated system performance to search for the optimum solution. After statistical water demand and renewable energy sources (wind, solar) availability are obtained, the features of the system are calculated
Performance Analysis of Thermal Energy Storage (TES) Systems based on Sensible and Latent Heat for Concentrated Solar Power (CSP) Applications
No full textThe research on thermal energy storage (TES) systems carried
out by the Department of Mechanical, Chemical and Materials Engineering
(DIMCM) of the University of Cagliari focuses on sensible and latent heat.
In these last years, several research projects have concerned the
characterization of this kind of TES systems by developing mathematical
models, for simulating and predicting performance, and implementing
laboratory facilities. In particular, the last studies frame mainly in two
research projects. The first one concerns the performance evaluation of a
sensible heat TES system composed of a tank filled with solid beads
(packed bed) crossed by air used as heat transfer fluid (HTF). The second
one aims to compare the performance of latent heat TES systems of
different geometrical configurations. The present paper reports some
results, introduced by a brief description of the technology
Le lingue tra i cinesi d'Italia
No full textIl capitolo descrive i risultati di un'indagine sul campo relativa al repertorio linguistico di un campione rappresentativo di minori immigrati a Bergamo, con note specifiche su quelli provenienti dalla Repubblica Popolare Cinese. Inoltre si descrive il processo di acquisizione dell'italiano L2 da parte di sinofoni
Techno-economic comparison of different thermal energy storage technologies for medium-scale CSP plants
No full textThis paper is focused on the ongoing studies at the Ottana Solar Facility, a new experimental power plant located in Sardinia (Italy). The Ottana solar facility includes a 630 kWe CSP plant and a 400 kWe CPV plant. With reference to the CSP section, a solar field based on Fresnel technology with a net collecting area of about 8600 m2 is used to heat up a Heat Transfer Fluid (HTF) trough solar energy. A Turboden 6HR Special ORC unit is used for the thermal to electrical energy conversion by means of a regenerative Rankine cycle operated by an organic fluid. The system is also equipped with a two-tank direct Thermal Energy Storage (TES) system with a storage capacity of about 15 MWht. However, other possible configurations of the TES section are currently under investigation. In this regard, asingle-tank packed-bed TES system based on encapsulated phase-change materials (PCM) is proposed in this study as an alternative to the two-tank direct TES system currently in operation. A techno-economic analysis has been therefore carried out to compare the two TES configurations. A mathematical model has been developed under MATLAB environment for assessing the expected yearly performance of the plant. Finally, a preliminary economic analysis based on the calculation of the levelized cost of storage has been conducted. The results show that a decrease in the overall energy production occurs with the use of the single-tank TES system due to a general decrease of the HTF temperature feeding the ORC unit, as a consequent of the indirect heat exchange. On the other hand, the lower investment costs arising from the lower volume of oil and the use of a sole tank make the proposed TES alternative more attractive from an economic point of view
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
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