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1.
Sensors (Basel) ; 19(22)2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31717425

RESUMO

In this work, we present an integrated photogrammetric-acoustic technique that, together with the construction of a scaled wind tunnel, allows us to experimentally analyze the permeability behavior of a new type of acoustic screen based on a material called sonic crystal. Acoustic screens are devices used to reduce noise, mostly due to communication infrastructures, in its transmission phase from the source to the receiver. The main constructive difference between these new screens and the classic ones is that the first ones are formed by arrays of acoustic scatterers while the second ones are formed by continuous walls. This implies that, due to their geometry, screens based on sonic crystals are permeable to wind and water, unlike the classic ones. This fact may allow the use of these new screens in sandy soils, where sand would pass through the screen, avoiding the formation of sand dunes that are formed in classic screens and drastically reducing their acoustic performance. In this work, the movement of the sand and the resulting acoustic attenuation in these new screens are analyzed qualitatively, comparing the results with those obtained with the classic ones, and obtaining interesting results from the acoustic point of view.

2.
Sensors (Basel) ; 19(22)2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31739529

RESUMO

The conservation and authentication of pictorial artworks is considered an important part of the preservation of cultural heritage. The use of non-destructive testing allows the obtention of accurate information about the state of pictorial artworks without direct contact between the equipment used and the sample. In particular, the use of this kind of technology is recommended in obtaining three-dimensional surface digital models, as it provides high-resolution information that constitutes a kind of fingerprint of the samples. In the case of pictorial artworks with some kind of surface relief, one of the most useful technologies is structured light (SL). In this paper, the minimum difference in height that can be distinguished with this technology was estimated, establishing experimentally both the error committed in the measurement process and the precision in the use of this technology. This study focused on the case of oil paintings on canvas and developed a low-cost system to ensure its wide use.

3.
Ultrasound Med Biol ; 45(3): 867-884, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30600128

RESUMO

The correction of transcranial focused ultrasound aberrations is a relevant issue for enhancing various non-invasive medical treatments. The emission through multi-element phased arrays has been the most widely accepted method to improve focusing in recent years; however, the number and size of transducers represent a bottleneck that limits the focusing accuracy of the technique. To overcome this limitation, a new disruptive technology, based on 3-D-printed acoustic lenses, has recently been proposed. As the submillimeter precision of the latest generation of 3-D printers has been proven to overcome the spatial limitations of phased arrays, a new challenge is to improve the accuracy of the numerical simulations required to design this type of ultrasound lens. In the study described here, we evaluated two improvements in the numerical model applied in previous works for the design of 3-D-printed lenses: (i) allowing the propagation of shear waves in the skull by means of its simulation as an isotropic solid and (ii) introduction of absorption into the set of equations that describes the dynamics of the wave in both fluid and solid media. The results obtained in the numerical simulations are evidence that the inclusion of both s-waves and absorption significantly improves focusing.


Assuntos
Ablação por Ultrassom Focalizado de Alta Intensidade/instrumentação , Lentes , Impressão Tridimensional , Acústica , Simulação por Computador , Humanos , Crânio/diagnóstico por imagem
4.
Sensors (Basel) ; 14(5): 7992-8002, 2014 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-24803191

RESUMO

Artworks are a valuable part of the World's cultural and historical heritage. Conservation and authentication of authorship are important aspects to consider in the protection of cultural patrimony. In this paper we present a novel application of a well-known method based on the phase-shift analysis of an ultrasonic signal, providing an integrated encoding system that enables authentication of the authorship of wooden panel paintings. The method has been evaluated in comparison with optical analysis and shows promising results. The proposed method provides an integrated fingerprint of the artwork, and could be used to enrich the cataloging and protection of artworks. Other advantages that make particularly attractive the proposed technique are its robustness and the use of low-cost sensors.


Assuntos
Interpretação de Imagem Assistida por Computador/métodos , Teste de Materiais/instrumentação , Pintura/análise , Pinturas/classificação , Robótica/instrumentação , Ultrassonografia/instrumentação , Madeira/análise , Algoritmos , Desenho de Equipamento , Análise de Falha de Equipamento , Interpretação de Imagem Assistida por Computador/instrumentação , Teste de Materiais/métodos , Robótica/métodos , Transdutores , Ultrassonografia/métodos
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