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The present work is about an acoustic design for a former church converted into a multi-purpose auditorium. The current status of the hall has been classified by means of an acoustic measurements campaign complying with technical standards requirements. A numerical model, which has been calibrated through the measured values, led to the development of the acoustic design that includes sustainable and not-invasive interventions. In contrast with the practical habits, which would use a large amount of sound absorbing materials, an array of suspended reflecting panels over the musicians positions has been introduced. Exploiting the reflecting and scattering properties of those objects, sound clarity and speech definition improve. All the treatments are validated using numerical simulation softwares in order to estimate the efficiency of the whole improvement proposal. IN_BO. Ricerche e progetti per il territorio, la città e l'architettura, V. 8, N. 11 (2017): IL FUTURO DEGLI EDIFICI DI CULTO: PAESAGGI. A cura di Luigi Bartolomei

After being neglected for a long time, in the last years, ships have been recognized and studied as sound emitters. The sound energy they generate impacts the outside, but it can also affect the indoor quality of life if the environments are not properly designed. In fact, acoustic comfort plays a pivotal role, particularly in recreational crafts. In the present work, room acoustics and acoustic camera measurements were performed, inside a 50 m length overall yacht, chosen as a case study in order to evaluate the acoustic comfort. The Italian classification procedure UNI 11367:2010 for buildings was applied, and results have been compared to other international comfort classes. However, all of these are based on prescription for standard buildings, and the present work highlights that they do not account for the effective ship’s acoustic issues: sound energy transfer from impacts over ceilings and sound energy leakage. While attention of shipbuilders in acoustic comfort is shown in the measured good reverberation times, the acoustic camera revealed sound energy leakages corresponding to hidden escape ways that have been poorly insulated. This compromises the standardized sound difference between contiguous compartments and also the thermal insulation, as leakage involves air passages. The present work attempts to evolve the classification procedure by also including, for the first time, the reverberation time, but future studies focused on finding correct standardized impact level noise for ship cases are needed. In fact, their values were very high and not comparable with those measured in actual buildings and for which reference values have been designed.

AbstractThe aim of this paper is to evaluate the thermal behaviour of a massive building during summer period. Experimental investigations were carried out on “Caserma Gaetano Abela”, an historical building located in Siracusa (Italy). The researchers have investigated the variation of both walls and indoor air temperatures in two rooms located on the east and west-facing sides. Two different experimental set-up were conducted, the first without allowing nocturnal ventilation, while the second with nocturnal ventilation obtained by opening the windows from 8:00 pm to 8:00 am. Based on the measurements of several physical parameters, the thermal lag and the decrement factor were calculated for the two ways of building ventilation management. The thermal comfort in the two offices was evaluated using the PMV and PPD indices. Results show that the high thermal inertia mass combined with natural ventilation reduces the indoor temperature during the nocturnal period, however the passive strategies resulted insufficient to obtain thermal comfort conditions during the following daytime hoursic correction. Globally it is possible to obtain an improvement of RT60 from 7.3 to 2.5 s at 1kHz and STI increases from 33.0% to 40.0%, at 1000Hz.

Statistical vibroacoustics, also called statistical energy analysis (SEA) in the field of engineering, is born from the application of statistical physics concepts to the study of random vibration in mechanical and acoustical systems. This article is a discussion on the thermodynamic foundation for that approach with particular emphasis devoted to the meaning of entropy, a concept missing in SEA. The theory focuses on vibration confined to the audio frequency range. In this frequency band, heat is defined as random vibration that is disordered vibration and temperature is the vibration energy per mode. Always in this frequency band, the concept of entropy is introduced and its meaning and role in vibroacoustics are enlightened, together with the related evolutionary equation. It is shown that statistical vibroacoustics is non-equilibrium thermodynamics applied to the audio range.

An evaluation was made of the behaviour of the dynamic parameters of the stapedius contraction reflex (latency, amplitude, recruitment time, duration, and efficiency) in response to stimuli with the same energy content but of different duration. A comparison was made with the results of a similar experiment in which stimuli with different energy contents were used. As adumbrated in earlier studies, it was found that these parameters are more subject to the influence of the temporal characteristics of the stimulus than to its energy content.

The aim of this document is to identify the current thermal, acoustic, seismic, technical, safety and environmental directives, standards and regulations, which apply to the various e-SAFE retrofit solutions at European level. Then, a preliminary analysis of the expected thermo-hygrometric, acoustic, seismic, technological and safety performances of the various solutions and technologies deployed is presented and discussed in detail in order to point out potential issues needing further detailed studies. The activity has also assessed the relevance of the existing normative framework, both at component and system level, in order to derive specifications for the e-PANEL and e-CLT products development.

The paper, at first, discusses theoretical aspects of acoustic wave propagation in lead tungstate (PWO). After that, it introduces the application of laser ultrasonics to PWO crystals with the aim of measuring the acoustic properties and the absorbed energy. A specific set-up has been developed to deposit energy in the crystals by means of shock waves generated by a pulsed Nd-YAG laser. We measured the acoustic properties of the PWO crystals along the crystallographic c^ axis and measured the acoustic energy absorption. Calculations confirmed that the majority of the energy has been absorbed in the samples. Since in scintillating crystals the radiation damage leads to a decrease in the optical transmission, the paper formulates the hypothesis that the laser energy absorbed can sustain recovery of the optical transmittance properties. Preliminary tests of light transmittance measurements showed a systematic improvement of optical transmittance after laser treatment in a series of PWO samples. These results are consistent and in agreement with the hypothesis, and they support the feasibility of a laser-based method to recover radiation-damaged crystals.

Two different configurations of adhesive-bonded carbon fiber-reinforced plastic (CFRP) specimens, joggled lap-joint specimens and single lap-joint specimens, are mechanically tested. The mechanical tests show that the joggled lap specimens have lower strength than the single lap specimens. The damage modes in both the specimens are analysed by the Acoustic Emission descriptors recorded during the mechanical tests. The acoustic data as cumulative counts and cumulative energy show the critical points of failure in both the specimen groups under loading. Moreover, they also show that the damage modes in both the specimens are dissimilar. Finally, the data provided by acoustic emission descriptors are verified by fractographic analysis on the failed surface.