1,721,495 research outputs found
Progetto Preliminare del Laboratorio di Caratterizzazione Radiologica mediante Tecniche di Analisi Distruttive
Full text linkLa progettazione di un Laboratorio Radiochimico di caratterizzazione dei rifiuti radioattivi sul suolo italiano, di categoria A secondo il DLgs 230/95 e s.m.i., capace di poter svolgere ricerca a livello nazionale ed internazionale e di lavorare in stretta sinergia con una rete di laboratori similari, rappresenta un compito impegnativo per chi è preposto alla realizzazione. Sfruttando le esperienze accumulate in anni di lavoro dalle competenze presenti nella struttura FPN RAD di ENEA, viene proposto uno schema generico di laboratorio da allestire sul suolo nazionale tenendo conto delle caratteristiche geomorfologiche del suolo e del contesto socio-economico su cui il laboratorio insiste
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
Environmental impact assessment of renewable energy communities: the analysis of an Italian neighbourhood
Full text linkIn recent years, research in renewable energy community (REC) schemes, coupling renewable energy sources and building energy efficiency, is gaining momentum. In this context, Urban Building Energy Modelling tools (UBEMs) have proved to comply with the design requirements of such schemes. However, a clear methodology exploiting UBEMs to support the design of RECs is still missing, especially for assessing the greenhouse gas (GHG) emissions associated with their specific technical configuration. Here, the REC is modelled in “urban modeling interface” (umi), one of the main bottom-up physics-based UBEMs. A building archetype approach is exploited to model the scenarios and assess embodied GHG emissions. The proposed methdology gives the possibility to investigate both the embodied and operational emissions for different REC configuration. A residential neighbourhood in Italy is selected as case study. The results demonstrate the importance of considering building characteristics when analysing emissions reductions in energy-sharing schemes, underlining the necessity of coupling the REC design with energy retrofit interventions
A new statistical approach to identify critical mass flow rate in CO2 nozzles near saturation conditions
No full textThe pressing needs to increase efficiency in heat pumps require refined design of various system components. In common reverse cycles, the throttling valve performs pure energy dissipation, and therefore it is well suited to be replaced by technologies such as ejectors and turbines, to augment system performance. In both two-phase turbines and two-phase ejectors a supersonic convergent-divergent nozzle is commonly required, which is responsible for accelerating the refrigerant fluid from the high-pressure part (e.g. condenser) to the low pressure part (e.g. evaporator). In the design phase of these nozzles, the accurate prediction of the maximum mass flow rate, also known as the critical mass flow rate, is particularly complex due to the two-phase nature of the expansion. In this paper, a new statistical approach to determine the value of the critical mass flow rate for CO2, as refrigerant fluid, is presented and assessed. This approach is based on the MF (Massflow Factor) parameter, which well correlates the value of mass flow rate in sonic conditions. The relationship shown here is based on open experimental information and it is validated on data from the open literature and the industry. The relative error on critical flow rate is less than 15% in the validation range, placing this statistical approach at a level of accuracy comparable to other physical models. An example of design is provided in this paper to demonstrate the potential of the relationship found. This approach provides the designer with a straightforward and validated basis for a reliable preliminary design of expanding two-phase nozzles
Effects of COVID-19 confinement on the simulation of energy needs and uses of residential buildings in Milan
Full text linkThis paper examines the impact of COVID-19 confinement on the simulation of energy needs and uses of residential buildings in Milan. Data-driven schedules for electricity use before and during lockdown, derived from smart metering data, are applied to an urban building energy model to analyze their effects on energy needs for heating and cooling and the energy use for lighting and for other services. Electricity uses, heating and cooling needs, and total primary energy (TOE) are compared for pre-COVID and during-COVID cases. Electricity increases by 8%, while heating decreases by 10%, and cooling increases by 26%. The 5% decrease in TOE is mainly due to the decrease in heating. The study uses heat maps to display the coefficient of variation of root mean square error (CVRMSE) at different temporal and spatial aggregations, indicating significant differences between pre- and during-COVID cases. The CVRMSE for electricity consumption is highest at the hourly level for single buildings, reaching a maximum of 44, and decreases at higher levels of aggregation. The CVRMSE for TOE is highest at the hourly level for single buildings, reaching a maximum of 230. A scenario is created by combining during-COVID and pre-COVID schedules for a hybrid work model, called post-COVID. The post-COVID scenario results indicate a significant impact of remote work on energy consumption patterns
Cavitation tunnel in Naval Architecture: from cavitation prediction to radiated noise
No full textCavitation tunnels represent one of the most important typologies of model test ing facilities used in Naval Architecture These facilities are employed to study the hydrodynamics of marine propellers, with special attention on cavitation and its side effects. These effects include: loss of propeller thrust and efficiency, erosion, inboard noise and vibration, underwater ra diated noise. The latter aspect is one of the hot topics in the field of ship h ydrodynamics because of the concerns related to its impact on marine life. This paper presents the general setup and test procedures used to predict the propeller radiated noise based on model tests. In addition, some of the main experimental issues relate d to these activities are described
Wake Instabilities of Tip-Loaded Propellers: Comparison between CLT and “New Generation” CLT Configurations
No full textTip loading is a common strategy to increase the propulsive efficiency of propellers. Solutions such as contracted and tip-loaded (CLT) and “New generation” CLT propellers exploit the presence of an endplate (“true” or as the result of a dedicated modification of the rake distribution) to sustain the increased load at the tip of the blade, at the cost of more complex vortical structures. Their evolution, and the mutual interaction of secondary vortices originated by the endplate itself, however, has not been completely and deeply investigated. The current paper addresses this topic by improved delayed detached eddy simulations (IDDES) of the flow field around two propellers of this type at different loading conditions. The presence of secondary vortices from the endplate root (or from the bended blade at tip), partially observed in recent experiments, is evidenced by high-fidelity CFD calculations. The interaction mechanism with the primary vortices (those from the endplate tip), and the resulting strengthening of the vortical structures, also through the interaction with the blade trailing vortical wake that promote the leapfrogging phenomenon, is discussed as well, comparing the phenomena in the case of two optimally designed geometries (a CLT and a New Generation CLT propeller) exploiting the same pressure side tip-loading concept in a slightly different way. Results show a rather different instability mechanism depending on the endplate configuration and open the discussion on the effectiveness of splitting a single tip vortex into pairs of vortical structures that may induce similar (or even worse) side effects in terms of pressure minima in the wake and earlier wake destabilization
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