1,721,179 research outputs found
Computational modelling of outdoor wind flow and indoor airflow in a cross-ventilated office building
No full textRain on building façades
No full textRain is one of the main causes of moisture damage to the building envelope, leading to problems such as rain penetration, frost and salt damage, discoloration by leaching, soiling by differential washing, etc. The potential of deterioration due to rain depends on the façade material, the junction of building envelope components, the overall geometry of the building, but also the presence or absence of modulation on the façade. In this paper, Computational fluid dynamics (CFD) simulations are used to analyze these effects and illustrated with examples taken in Sicily. It is firstly shown that buildings protect themselves from driving rain due to the wind blocking effect, but that façade openings can lead to increased deposit of driving rain due to occurrence of high wind velocities originating from pressure shortcuts. The importance of façade modulation by cornices or roof overhangs for shelter and deflection of rain is next demonstrated. It is further highlighted that these modulations should include drips to shed rain water running down the façade. Façades without moisture buffering by capillary action of façade materials are found to be very sensitive to staining due to run-off of dirty water from horizontal modulations. Finally, an example illustrates the sensitivity to rain penetration and degradation of face-seal façades
Static downscaling of mesoscale wind conditions into an urban canopy layer by a CFD microscale model
Full text linksponsorship: The authors gratefully acknowledge the Port Authority of Livorno for the use of data obtained by its anemometric monitoring network. The LiDAR LI51 was funded by the European Cross -border Programme Italy/France "Maritime" 2007-2013 through the "Wind, Ports, and Sea" (CUP: B82F13000100005) project. The anemometric campaign in Livorno was carried out and stations A1 and A2 purchased in the framework of Project "Wind monitoring, simulation and forecasting for the smart management and safety of port, urban and territorial systems", funded by Compagnia di San Paolo (grant number 2015.0333, ID ROL: 9820) . Alessio Ricci is a postdoctoral fellow of the Research Foundation - Flanders (project FWO 1256822N) and its financial support is gratefully acknowledged. (European Cross -border Programme Italy/France "Maritime" 2007-2013 through the "Wind, Ports, and Sea" project|CUP: B82F13000100005, Compagnia di San Paolo|2015.0333, Compagnia di San Paolo|ROL: 9820, Research Foundation - Flanders|FWO 1256822N)status: Publishe
Simulation of urban boundary and canopy layer flows in port areas induced by different marine boundary layer inflow conditions
Full text linkComputational fluid dynamics (CFD) simulations and wind-tunnel (WT) tests can be considered as boundary-value problems, where the inlet boundary condition, which is usually obtained inferring inlet mean wind profiles from on-site measurements or other type of experimental data, represents the large-scale atmospheric forcing exerted at the outer limit of the urban model. It is not clear, however, to which extent the choice of different inflow wind speed profiles may affect WT and CFD results in the urban environment. In the present study, this aspect is investigated through the comparison of the wind flow fields simulated numerically and tested experimentally in an atmospheric boundary layer wind tunnel (ABLWT) within a district of Livorno city, Italy, called “Quartiere La Venezia”. Three different shapes of inflow profiles were tested using the CFD technique and the results were compared with each other: one is based on the approach-flow profiles measured upstream of the urban model in the WT test section (WT profile) and two are based on anemometric data corresponding to the approach-flow profile measured by means of a LiDAR wind profiler (LiDAR profile 1 and 2). The analysis showed that using different wind speed profiles does not affect significantly the results in the urban canopy layer (UCL), where correlations of 95% and 98% were found between the LiDAR profile 1 and 2 data and the WT profile data (at z = 0.02 m above the bottom), respectively. Conversely, the different inflow profiles strongly affected the results above the UCL. This means that the local-scale effects induced on the wind field in the UCL by the urban texture are dominated mainly by the larger-scale forcing, as within the canopy the flow remains topologically invariant despite the different inflow conditions
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
Numerical Investigation of the Impact of Morphological Parameters on Urban Ventilation in Compact Cities
No full textThe present work investigates the ventilation performance of a compact area in Rome, Italy, performing 3D steady-state Reynolds-averaged Navier–Stokes simulations for twelve wind directions. The urban ventilation is expressed in terms of the spatially averaged mean wind speed ratios at pedestrian level, γped, and at 10 m height, γ10. The urban morphology is quantified using morphological parameters (MPs). The relations between each MP and γped and γ10 are expressed through simple models obtained using linear regression analysis. The relations present strong correlations with R2 up to 0.89. The provided linear models can be valuable tools for highlighting areas potentially vulnerable to poor air conditions without running simulations
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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