Search Results (7)

This document provides a comprehensive overview of in-field measurements of acoustic and environmental conditions in three university lecture halls, focusing on their impact on student activity levels. The study, conducted at the University of Bologna, aims to measure student activity (SA) levels under unfavorable comfort conditions: high occupancy density, low teacher intelligibility, and absence of ventilation. The measurements show that, under these conditions, the student activity level is neither correlated with the room’s thermo-hygrometric conditions nor occupancy levels. The results, on the other hand, indicate that there is an inverse relationship between the SA level and occupancy: the higher the occupancy, the lower the SA level. Under conditions of high occupancy density and suboptimal thermal conditions, the mechanisms underlying student activity appear to differ from those observed in previous studies conducted under lower occupancy density. In the latter, an increase in SA levels was measured as occupancy increased. In contrast, the present study highlights an inverse behavior where students tend to reduce their activity as the number of students increases. Full article

Sound absorbing micro-perforated panels (MPPs) are being increasingly used because of their high quality in terms of hygiene, sustainability and durability. The present work investigates the feasibility and the performance of MPPs when used as an acoustic treatment in lecture rooms. With this purpose, three different micro-perforated steel specimens were first designed following existing predictive models and then physically manufactured through 3D additive metal printing. The specimens’ acoustic behavior was analyzed with experimental measurements in single-layer and double-layer configurations. Then, the investigation was focused on the application of double-layer MPPs to the ceiling of an existing university lecture hall to enhance speech intelligibility. Numerical simulations were carried out using a full-spectrum wave-based method: a finite-difference time-domain (FDTD) code was chosen to better handle time-dependent signals as the verbal communication. The present work proposes a workflow to explore the suitability of a specific material to speech requirements. The measured specific impedance complex values allowed to derive the input data referred to MPPs in FDTD simulations. The outcomes of the process show the influence of the acoustic treatment in terms of reverberation time (${\mathrm{T}}_{30}$) and sound clarity (${\mathrm{C}}_{50}$). A systematic comparison with a standard geometrical acoustic (GA) technique is reported as well. Full article

Attending an opera involves a multi-sensory evaluation (acoustical, visual, and more), cultural background and other emotional parameters. The present work aims to investigate the historical development of Italian-style opera houses, from the 16th century until today. Called “Italian” due to their origin, they developed thanks to the mutual influence of the genre and the building characteristics. Furthermore, the acoustics of historical opera houses is now considered as intangible cultural heritage, so it should be known and preserved. The paper addressed the state-of-the-art literature—most of which was proposed in Italian—which can be driven easily by the sharing of historical and contemporary knowledge. Full article

We report on the numerical simulations and experimental validation of a microwave planar sensor based on two coupled rings operating in the 4–6 GHz range. The fabricated sensor is used to characterize the dielectric permittivity of vegetable oils. We optimized the geometrical parameters in order to improve the overlap between the oil samples under study and the electric field. The experimental results showed an excellent match with the simulation results. The fabricated sensor allowed to retrieve the oil permittivity with a sensitivity of about 35 MHz per permittivity unit in the frequency range of interest. This paves the way to the realization of compact and sensitive sensors for a wide plethora of fields ranging from industry and food to chemistry and biology. Full article

In a Historical Opera House (HOH), the proscenium is the foreground part of the stage. Until the end of the 19th Century, it was extended through the cavea, being the orchestra placed at the same level of the stalls, without an orchestra pit. Soloists often moved in the proscenium when they sung, in order to increase the strength of the voice and the intelligibility of the text. The Alighieri theatre in Ravenna, designed by the Meduna brothers, the former designers of Venice’s “La Fenice” theater, is chosen as a case study. During a refurbishment in 1928, the proscenium of the stage was removed in order to open the orchestra pit, which was not considered in the original design. The original design and the present one are compared by using numerical simulations. Acoustic measurements of the opera house and vibro-acoustic measurements on a wooden stage help to reach a proper calibration of both models. Results are discussed by means of ISO 3382 criteria: the proscenium increases the sound strength of the soloists but reduces the intelligibility of the text. Full article

The foundation of architectural acoustics as an independent science is generally referred to Sabine’s early studies and their application. Nevertheless, since the 16th Century, a great number of authors wrote essays and treatises on the design of acoustic spaces, with a growing attention to the newborn typology of the Opera house, whose evolution is strongly connected to the cultural background of the Italian peninsula. With roots in the Renaissance rediscovery of Vitruvius’s treatise and his acoustic theory, 16th- to 19th-Century Italian authors tackled several issues concerning the construction of theatres—among them, architectural and structural features, the choice of the materials, the social meanings of performances. Thanks to this literature, the consolidation of this body of knowledge led to a standardisation of the forms of the Italian Opera house throughout the 19th Century. Therefore, the scope of this review paper is to focus on the treatises, essays and publications regarding theatre design, written by pre-Sabinian Italian scholars. The analysis of such literature aims at highlighting the consistencies in some 19th-Century minor Italian Opera houses, in order to understand to what extent this scientific and experimental background was part of the building tradition during the golden age of the Italian Opera. Full article

Promotion of retrofit actions on existing buildings is a goal in Italy, since most of them were built before the 80′s when little attention was paid to energy saving. This paper presents an integrated passive design approach to reduce the heating demand and limit the costs of a representative existing residential complex located in Bologna, in the northern part of Italy. To this purpose, we explored different scenarios upon actions taken on the building structure: (1) High efficiency windows; (2) additional insulation on the external walls; or (3) the simultaneous application of high efficiency windows and improved thermal envelope, on both external walls and roofing. The numerical optimization has been performed dynamically using TRNSYS simulation tool, to evaluate energy consumptions in different structural conditions. Then, the developed model has been calibrated by the real consumption data deduced from energy bills (years 2009–2015). Finally, the energy results obtained in the above mentioned different scenarios have been evaluated under an economic assessment of cost investment: It has been highlighted that the payback time (PBT) results to be strongly influenced by the national policies of fiscal incentives. According to the present model, the most profitable condition is obtained when additional insulation on the external walls is applied: The total amount of energy saving resulted to be equal to 930.4 MWh, with an optimal PBT of roughly six years, when tax refund was contemplated. Full article