Search results for "ACOUSTIC"
showing 10 items of 1590 documents
The role of the Krauss’s organ in sound production in Pamphagidae (Caelifera: Orthoptera).
2012
In Pamphagidae, the Krauss’s organ is located on both sides of the 2nd tergite and its function is superficially known. It has been proposed to have a stridulatory function. This organ can be found in all Pamphagidae except the apterous genera. Rearing specimens of some species and observing mounted pamphagids allowed the author to observe that when the Krauss’s organ is absent (most apterous species) the tympanum is also absent; further, he discovered specialized stridulatory structures on hind femurs of some taxa for sound emission. By rearing two Pamphagidae belonging to different genera, fragments of stridulations involving the Krauss’s organ and specialized structures on the hind femur…
Detection and mapping of Posidonia oceanica dead matte by high-resolution acoustic imaging
2009
A high-resolution echosounder was used to acquire seismo-acoustic records of P. oceanica dead matte patches in the Gulf of Palermo. Seismo-acoustic profiling enabled detection of dead matte structures that are invisible to visual inspection, being hidden by variable layers of sandy sediment. The thickness of the dead matte measured reaches a maximum of 2.2 m. The mean volume of the matte per unit area of seabed surface (MEIx) varies from 0.2 to 2.2 m 3 /m 2 , with an average value of 1.6 m 3 /m 2 and a total volume estimated at 73,000 m 3 . From literature data and from the volume of dead matte calculated in the present work we estimated that total carbon accumulated in the matte is about 2…
The use of high-resolution seismo-acoustic echosounder imaging for estimation carbon sink in P. oceanica dead matte
2009
Exploring Historical Scientific Instruments by Using Mobile Media Devices
2022
We describe an educational activity that can be completed with mobile media devices in order to understand the working principle of a pair of tuning forks, from the Historical Collection of Physics Instruments of the University of Palermo, and how they were used to explain acoustic interference and beats with the Lissajous optical method. This approach can be used with any tuning fork and it is a valuable teaching strategy that does not require specific laboratory equipment.
The Collection of historical instruments of Acoustics of the University of Palermo
2018
La Collezione Storica degli Strumenti di Fisica dell’Università di Palermo, esposta presso il Dipartimento di Fisica e Chimica, nell’edificio storico di Via Archirafi 36, conserva circa venti strumenti di Acustica. Per la maggior parte, questi strumenti sono stati realizzati nella seconda metà del XIX secolo a Parigi dal costruttore Rudolph Koenig e acquistati dal fisico Pietro Blaserna durante la sua permanenza a Palermo quale titolare della cattedra di Fisica Sperimentale. Nel presente articolo viene descritta brevemente la Collezione Storica degli Strumenti di Fisica, e in particolare tre strumenti di Acustica. In the Historical Collection of Physics Instruments of the University of Pale…
A study of the acoustic parameters of ancient theaters
2013
Although many centuries have passed, in many ancient theatres evocative theatrical performances still take place, especially during summer. Greek and Latin architects care for equilibrium of proportions offers not only an intense quality of view but also a high quality acoustics. In our study we did an analysis both theoretical and experimental of the acoustic parameters of the ancient theaters of Syracuse, Segesta, and Akrai, in Sicily and the theater of Bulla Regia, in Jendouba (Tunisia), it was only simulated, because of the inability to reach the scene for reasons due to the political turmoil. A measurement session was carried out by our team in the framework of a wide research project …
On the Use of Two Emerging Laser-Based Flaw-Detection Techniques – Considerations and Practicalities
2023
The pursuit of non-contact techniques for detecting ultrasonic waves propagating on the surface of solids is stimulated by the possibility of gaining some advantages over conventional contact methods. Non-contact methods are becoming a milestone in performing non-destructive evaluation in several industrial fields, where hazardous environments, narrow spaces, high temperatures, and complex geometries are encountered. Such methods exploit photo-acoustic interactions between light and sound waves. This work compares two non-contact laser-based methods for detecting artificial flaws of different sizes in metallic specimens. It uses multi-signal homodyne interferometry and single beam deflectom…
Automatic classification of acoustically detected krill aggregations: A case study from Southern Ocean
2022
Acoustic surveys represent the standard methodology to assess the spatial distribution and abundance of pelagic organisms characterized by aggregative behaviour. The species identification of acoustically observed aggregations is usually performed by taking into account the biological sampling and according to expert-based knowledge. The precision of survey estimates, such as total abundance and spatial distribution, strongly depends on the efficiency of acoustic and biological sampling as well as on the species identification. In this context, the automatic identification of specific groups based on energetic and morphological features could improve the species identification process, allo…
A study of temporal estimation from the perspective of the Mental Clock Model.
2009
M. Cardaci's (2000) Mental Clock Model maintains that a task requiring a low mental workload is associated with an acceleration of perceived time, whereas a task requiring a high mental workload is associated with a deceleration. The authors examined the predictions of this model in a musical listening condition in which musical pieces were audible in several structural complexities. To measure the effects of musical complexity on time estimation, the authors used retrospective and prospective time-estimation paradigms. For the retrospective paradigm, the authors invited participants to listen to a musical piece and then estimate its duration. For the prospective paradigm, the authors invit…
Heterogeneous shear elasticity of glasses: the origin of the boson peak
2013
The local elasticity of glasses is known to be inhomogeneous on a microscopic scale compared to that of crystalline materials. Their vibrational spectrum strongly deviates from that expected from Debye's elasticity theory: The density of states deviates from Debye's law, the sound velocity shows a negative dispersion in the boson-peak frequency regime and there is a strong increase of the sound attenuation near the boson-peak frequency. By comparing a mean-field theory of shear-elastic heterogeneity with a large-scale simulation of a soft-sphere glass we demonstrate that the observed anomalies in glasses are caused by elastic heterogeneity. By observing that the macroscopic bulk modulus is …