1,720,999 research outputs found
Metodo per il calcolo di una posizione e l’eventuale mappatura di una variabile spazio-correlata tramite impiego di segnali acustici e corrispondente apparato per l’implementazione del metodo
No full textMetodo per il calcolo di una posizione e l’eventuale mappatura di una variabile spazio-correlata tramite impiego di segnali acustici comprendente le seguenti fasi: predisporre in corrispondenza di uno spazio tridimensionale di misura almeno tre emettitori acustici di posizione (A, B, C, D) con posizione relativa nota e almeno un ricevitore acustico (R) posto ad una distanza (D1, D2, D3, D4) non nota da ciascuno degli emettitori di posizione (A, B, C, D); far emettere a ciascun emettitore di posizione (A, B, C, D) un segnale acustico di posizione (X1, X2, X3, X4); acquisire, per mezzo del ricevitore acustico (R), un segnale acustico ricevuto (J) comprendente contributi legati ai singoli segnali acustici di posizione (X1, X2, X3, X4); ricavare un segnale identificativo di posizione (H1, H2, H3, H4) per ogni segnale acustico di posizione (X1, X2, X3, X4); ricavare, dai segnali identificativi di posizione (H1, H2, H3, H4), il tempo di volo (T1, T2, T3, T4); calcolare le distanze (D1, D2, D3, D4) a partire dai tempi di volo (T1, T2, T3, T4); calcolare la posizione (P) del ricevitore acustico (R) nello spazio tridimensionale di misura a partire da dette distanze (D1, D2, D3, D4)
Effect of slit-shaped leaks on airborne sound insulation of noise barriers
No full textThe airborne sound insulation performance of noise barriers can be adversely affected by sound leaks. The most common of them are very thin slit-shaped leaks occurring between panels or panel ad post. In this work, the effect of slit-shaped leaks is experimentally investigated using in an improved way the test method specified in CEN/TS 1793-5. The performance of the same noise barrier is tested in controlled conditions in the free field with and without an artificially done sound leak. The results at various distances are presented and commented. This paper discusses the comparison of the results and the conditions of validity
Evaluation of Thermal Comfort Inside an Office Equipped with a Fan Coil HVAC System: A CFD Approach
Full text linkAn accurate assessment of thermal comfort inside a building is essential since it is associated to the human’s perception of well-being and comfort. In the present study, a 3D computational fluid dynamic (CFD) code is employed to evaluate the indoor comfort indexes for a university office located in a historical building, built of thick masonry walls and of large single-glass windows, using fan coil as an air conditioning system. The experimental measurement has been carried out to validate the numerical model and to obtain the required initial and boundary conditions. The experimental set-up employs an innovative system for the sensor localization, based on acoustic sources, signal processing and trilateration algorithms. By means of finite volume method, the turbulent air flow, the local heat transfer characteristics and the operative temperature inside the room are obtained for a typical winter day. The results yielded by numerical simulations allow to evaluate thermal comfort condition at working places inside the office and to identify the best comfort areas. The results show that even when the air temperature is quite uniform inside the room, the operative temperature at the positions where occupants are placed is significantly affected by surface temperature of the windows, due to the large window to wall surface ratio and also by the position and operational condition of fan coil. It is concluded that 3D comfort map allows to optimize internal layout of the office room; furthermore, the possibility of thermal comfort optimization in specific workstation together with local control of heating system lead to gain remarkable energy saving results
Sound field measurements inside a reverberant room by means of a new 3D method and comparison with FEM model
No full textA newly developed low cost 3D positioning system is used to measure the sound field inside a reverberant room. The measurement is performed moving a microphone inside the reverberant room (excited with a multi-tone signal or with an MLS signal) and measuring, point by point, the local sound pressure level and the impulse response, in order to perform a modal analysis and compute a spatially localized reverberation time. The results of the measurements are compared with a FEM model of the reverberation room. The measurement system requires a normal computer, a standard multi-channel sound card and very few inexpensive external components such as 4 small amplified loudspeakers (used for the 3D positioning system) placed at known fixed positions and a microphone, used as probe for both the positioning and the sound field measurements. A dodecahedron is used to excite the reverberant room. The 3D measurement system is described in details
Acoustic Measurements on a Sonic Crystals Barrier
No full textAbstractThis paper describes the measurements carried out over a sonic crystal at normal incidence according to EN 1793-6, which allows to cancel ground reflection and edge diffraction by applying suitable windowing techniques. The sample was made of hollow PVC pipes with an outer diameter of 160mm arranged in a square lattice with lattice constant 0.2 m. FE predictions were computed in order to verify the experimental campaign. A good match between simulations and measurements was found in the first sonic Bragg band gap. As expected, increasing the number of rows does not translate into a shift of the Bragg band gap but into an increase of the insulation properties
La misura della trasmissione laterale nelle strutture in legno: problematiche e metodologie a confronto
No full textIl presente contributo presenta il confronto fra differenti tecniche di misura utilizzate per la valutazione della trasmissione laterale su giunti per strutture in cross laminated timber (CLT). La campagna di misure, voluta e finanziata da Rotho Blaas srl, è stata condotta in osservanza della normativa EN ISO 10848 [1] al fine di misurare i valori di indice di riduzione delle vibrazioni Kij utilizzabile per stimare in maniera predittiva il potere fonoisolante apparente secondo la normativa EN 12354 [2].
Scelta una configurazione di misura standard per un giunto parete-solaio, sono state effettuate misurazioni dei livelli di velocità e di riverberazione strutturale con diversi metodi. In entrambi i casi, i pannelli sono stati eccitati con una sorgente elettrodinamica fissata alla parete e con il martello strumentato, dotato di tre punte a coprire gli intervalli di frequenze di interesse.
Nel presente articolo sono dapprima illustrate le specifiche della catena di misura e l’analisi del segnale utilizzata per l’estrazione dei risultati. Poi sono riportati e discussi i risultati, in particolare con riferimento all'incidenza che ogni componente ha sul risultato finale.
Le metodologie di calcolo adottate seguono in maniera dettagliata le indicazioni della norma ISO 10848 [1] con lo scopo di confrontare i risultati di diverse metodologie di misura per valutare quale sia la più affidabile
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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