New analysis and extensions of split-spectrum processing algorithms

[EN] In this paper we compare the performances of different variants of split-spectrum algorithms and propose some new extensions based on the use of variable bandwidth filters equally spaced in frequency and energy gain equalized. Signal-to-Noise Ratio Gain and Flaw-to-Clutter Ratio Gain factors were selected as the figures of merit to make the comparisons among the different methods. We considered simulated ultrasonic signals using both stationary and non-stationary models for the grain noise, and real scans obtained in laboratory from low dispersive (aluminum) and high dispersive (cement) materials. Frequency Multiplication (FM) recombination method is revealed as the best option when combined with the new extensions.This work has been supported by the Ministerio de Fomento (Spain) and the Ministerio de Ciencia e Innovacion (Spain), and FEDER funds under the projects T39/2006, TEC2008-06728 and TEC2008-02975Rodríguez, A.; Miralles Ricós, R.; Bosch Roig, I.; Vergara Domínguez, L. (2012). New analysis and extensions of split-spectrum processing algorithms. NDT & E International. 45(1):141-147. https://doi.org/10.1016/j.ndteint.2011.10.001S14114745

Ultrasonic broadband signal monitoring of Glass-fiber Reinforced Cement (GRC) bending tests

[EN] In this study, complete ultrasonic monitoring of Glass-fiber Reinforced Cement plates under bending tests was addressed. In this kind of experiment, the mechanical properties of the specimen continuously change during the test, thus, the acquisition time of the ultrasonic signals is a critical variable. In order to overcome this drawback, a new ultrasonic procedure based on broadband signals (chirp) has been applied. Following this line of thought, the analysed ultrasonic parameters have been split into the parameters that only depend on time, and those that depend on both time and frequency. In particular,the frequency dependent attenuation parameter allows characterizing the evolution of the plate being damaged over a wide frequency range and significantly detecting the main two events happening during the experiment: the first crack and the maximum stress point. In short, this paper demonstrates the suitability of ultrasonic broadband signals for characterizing fiber-reinforced cementitious composites under bending stress.This work has been supported by the Spanish Administration under grants, BES-2015-071469, TEC2011-23403, BIA2014-55311-C2-1-P and BIA2014-55311-C2-2-P.Genovés, V.; Gosálbez Castillo, J.; Carrión García, A.; Miralles Ricós, R.; Paya Bernabeu, JJ. (2017). Ultrasonic broadband signal monitoring of Glass-fiber Reinforced Cement (GRC) bending tests. Cement and Concrete Composites. 80:55-63. https://doi.org/10.1016/j.cemconcomp.2017.02.009S55638

Design and Application of a Passive Acoustic Monitoring System in the Spanish Implementation of the Marine Strategy Framework Directive

[EN] A passive acoustic monitoring (PAM) device named SAMARUC has been developed to acquire underwater sounds following the specifications of the Monitoring Guidance for Underwater Noise in European Seas: Monitoring Guidance Specifications. Based on a Texas Instruments processor, an ultra-low power ADC was programmed to work at a sampling rate of 192 kHz and adhoc electronics were designed allowing the processor¿s two microSD buses to be used, thereby increasing the storage capacity. Many other software and hardware enhancements were implemented, such as the new low latency file system, the construction of NITUFF anodized aluminium housing and ringed buoys. With the resulting application, data obtained by the SAMARUC at El Gorguel (Cartagena, Spain) in 2018 were compared to a theoretical underwater noise map created using AIS data. This was done following the Descriptor D11.2 by means of the ambient noise level indicators at two one-third-octave frequency bands (63 Hz and 125 Hz), mainly related to marine traffic and noise pollution. The conjunction between the acquisition of underwater acoustic data and the development of a numerical propagation model was found to be highly recommendable to estimate the ambient continuous noise level when validating the acquired data as well as when correcting the prediction provided by the model.Lara, G.; Bou-Cabo, M.; Esteban, JA.; Espinosa Roselló, V.; Miralles Ricós, R. (2019). Design and Application of a Passive Acoustic Monitoring System in the Spanish Implementation of the Marine Strategy Framework Directive. MDPI. 1-7. https://doi.org/10.3390/ecsa-6-06568S1

Optimized ultrasonic attenuation measures for non-homogeneous materials

In this paper the study of frequency-dependent ultrasonic attenuation in strongly heterogeneous materials is addressed. To determine the attenuation accurately over a wide frequency range, it is necessary to have suitable excitation techniques. Three kinds of transmitted signals have been analysed, grouped according to their bandwidth: narrowband and broadband signals. The mathematical formulation has revealed the relation between the distribution of energy in their spectra and their immunity to noise. Sinusoidal and burst signals have higher signal-to-noise ratios (SNRs) but need many measurements to cover their frequency range. However, linear swept-frequency signals (chirp) improve the effective bandwidth covering a wide frequency range with a single measurement and equivalent accuracy, at the expense of a lower SNR. In the case of highly attenuating materials, it is proposed to use different configurations of chirp signals, enabling injecting more energy, and therefore, improving the sensitivity of the technique without a high time cost. Thus, if the attenuation of the material and the sensitivity of the measuring equipment allows the use of broadband signals, the combination of this kind of signal and suitable signal processing results in an optimal estimate of frequency-dependent attenuation with a minimum measurement time.This work has been supported by the Spanish Administration under grant BIA2014-55311-C2-2-P.Genovés Gómez, V.; Gosálbez Castillo, J.; Carrión García, A.; Miralles Ricós, R.; Paya Bernabeu, JJ. (2016). Optimized ultrasonic attenuation measures for non-homogeneous materials. Ultrasonics. 65:345-352. https://doi.org/10.1016/j.ultras.2015.09.007S3453526

Unknown Signal Detection by One-class Detector based on Gaussian Copula

[EN] One-class detector is an option to deal with the problem of detecting an unknown signal in a background noise, as it is only necessary to know the noise distribution. Thus a Gaussian copula is proposed to capture the dependence among the noise samples, meanwhile the marginals can be estimated using well-known methods. We show that classical energy detectors are particular cases of the proposed one-class detector, when Gaussian noise distribution is assumed, but are inappropriate in other cases. Experiments combining simulated noise and real acoustic events have confirmed the superiority of the proposed detectors when noise is non-Gaussian. An interpretation of the methods in terms of the Edgeworth expansion is also included.This work has been supported by Generalitat Valenciana under grant PROMETEO 2010-040 and by the European Commission under grant FP7-270318 (Art Sense).Soriano Tolosa, A.; Vergara Domínguez, L.; Moragues, J.; Miralles Ricós, R. (2014). Unknown Signal Detection by One-class Detector based on Gaussian Copula. Signal Processing. 96:315-320. https://doi.org/10.1016/j.sigpro.2013.09.011S3153209

Improved visualization of large temporal series for the evaluation of good environmental status

[EN] Passive acoustic monitoring of underwater sounds is an emerging discipline that can be used to guarantee that anthropogenic noise meets acceptable limits, to detect the presence of cetacean species, and to ensure sustainable exploitation of our oceans and seas. In this scenario, graphical representation techniques play a key role in helping to reveal seasonal structures of human made noises. Nevertheless, for very long temporal series, it might be challenging to find a graphic visualization technique that allows representing a time range that is long enough to capture these seasonal events, while at the same time preserving short isolated events. We propose a framework for the creation of such visualization techniques and analyze the different stages involved: data reduction, color encoding, and signal processing on graphs. All of this is applied to data from deployments in two marine protected areas in order to provide an acoustic panorama and identify seasonal events.This work was supported partially by the Fundacion Biodiversidad (various Spanish government ministries involved in nature conservation) and partially by the European Commission -DG ENV (grant agreement 11.0661/2016/748066/SUB/ENV.C2). We would like to thank all of the researchers from FGUA (UAH) and the Oceanografic (Valencia) who participated in the deployment and recovery of the acoustic recording devices. We also thank the authorities in charge of the Cabrera Archipelago Maritime-Terrestrial National Park as well as the Cabo de San Antonio Natural Marine Reserve for providing the corresponding permits to carry out the scientific work.Miralles Ricós, R.; Lara Martínez, G.; Gosálbez Castillo, J.; Bosch Roig, I.; León Fernández, A. (2019). Improved visualization of large temporal series for the evaluation of good environmental status. Applied Acoustics. 148:55-61. https://doi.org/10.1016/j.apacoust.2018.12.009S556114

New Insights into the Design and Application of a Passive Acoustic Monitoring System for the Assessment of the Good Environmental Status in Spanish Marine Waters

[EN] Passive acoustic monitoring systems allow for non-invasive monitoring of underwater species and anthropogenic noise. One of these systems has been developed keeping in mind the need to create a user-friendly tool to obtain the ambient noise indicators, while at the same time providing a powerful tool for marine scientists and biologists to progress in studying the effect of human activities on species and ecosystems. The device is based on a low-power processor with ad-hoc electronics, ensuring that the system has efficient energy management, and that the storage capacity is large enough to allow deployments for long periods. An application is presented using data from an acoustic campaign done in 2018 at El Gorguel (Cartagena, Spain). The results show a good agreement between theoretical maps created using AIS data and the ambient noise level indicators measured in the frequency bands of 63 Hz and 125 Hz specified in the directive 11 of the EU Marine Strategy Framework Directive. Using a 2D representation, these ambient noise indicators have enabled repetitive events and daily variations in boat traffic to be identified. The ship noise registered can also be used to track ships by using the acoustic signatures of the engine propellers¿ noise.Lara Martínez, G.; Miralles Ricós, R.; Bou-Cabo, M.; Esteban, JA.; Espinosa Roselló, V. (2020). New Insights into the Design and Application of a Passive Acoustic Monitoring System for the Assessment of the Good Environmental Status in Spanish Marine Waters. Sensors. 20(18):1-12. https://doi.org/10.3390/s20185353S1122018Lara, G., Bou-Cabo, M., Esteban, J. A., Espinosa, V., & Miralles, R. (2019). Design and Application of a Passive Acoustic Monitoring System in the Spanish Implementation of the Marine Strategy Framework Directive. Proceedings of 6th International Electronic Conference on Sensors and Applications. doi:10.3390/ecsa-6-06568SAMARUC Webhttp://samaruc.webs.upv.esExplora (Patents and Software) UPV Webhttps://aplicat.upv.es/exploraupv/ficha-tecnologia/patente_software/15065?busqueda=R-16202-2012Beghi, M. G. (Ed.). (2013). Modeling and Measurement Methods for Acoustic Waves and for Acoustic Microdevices. doi:10.5772/2581Oceans Physics at Your Fingertipshttps://www.emodnet-physics.eu/Map/Gridded Bathymetric Datahttps://www.gebco.net/data_and_products/gridded_bathymetry_data/Mackenzie, K. V. (1981). Nine‐term equation for sound speed in the oceans. The Journal of the Acoustical Society of America, 70(3), 807-812. doi:10.1121/1.386920Ross, D., & Kuperman, W. A. (1989). Mechanics of Underwater Noise. The Journal of the Acoustical Society of America, 86(4), 1626-1626. doi:10.1121/1.398685Gervaise, C., Kinda, B. G., Bonnel, J., Stéphan, Y., & Vallez, S. (2012). Passive geoacoustic inversion with a single hydrophone using broadband ship noise. The Journal of the Acoustical Society of America, 131(3), 1999-2010. doi:10.1121/1.3672688Crocker, S. E., Nielsen, P. L., Miller, J. H., & Siderius, M. (2014). Geoacoustic inversion of ship radiated noise in shallow water using data from a single hydrophone. The Journal of the Acoustical Society of America, 136(5), EL362-EL368. doi:10.1121/1.4898739Li, H., Yang, K., Duan, R., & Lei, Z. (2017). Joint Estimation of Source Range and Depth Using a Bottom-Deployed Vertical Line Array in Deep Water. Sensors, 17(6), 1315. doi:10.3390/s17061315Tong, J., Hu, Y.-H., Bao, M., & Xie, W. (2013). Target tracking using acoustic signatures of light-weight aircraft propeller noise. 2013 IEEE China Summit and International Conference on Signal and Information Processing. doi:10.1109/chinasip.2013.6625333Lo, K. W., Perry, S. W., & Ferguson, B. G. (2002). Aircraft flight parameter estimation using acoustical Lloyd’s mirror effect. IEEE Transactions on Aerospace and Electronic Systems, 38(1), 137-151. doi:10.1109/7.993235Miralles, R., Lara, G., Gosalbez, J., Bosch, I., & León, A. (2019). Improved visualization of large temporal series for the evaluation of good environmental status. Applied Acoustics, 148, 55-61. doi:10.1016/j.apacoust.2018.12.00

SAMARUC a Programmable system for Passive acoustic monitoring of cetaceans

[EN] This paper reports the work carried out by iTEAM researchers in Passive Acoustic Monitoring (PAM) for underwater monitoring of cetaceans. It includes a description of novel signal processing algorithms for detection and classification of aquatic mammal species as well as a hardware system called SAMARUC specially designed in collaboration with marine biologists.The authors would like to thank the funding received from the Ministerio de Ciencia e Innovación within the Project number TEC2011-23403.Miralles Ricós, R.; Lara Martínez, G.; Carrión García, A.; Esteban, JA. (2013). SAMARUC a Programmable system for Passive acoustic monitoring of cetaceans. WAVES. 5(1):69-76. http://hdl.handle.net/10251/52799S69765

Application of non-destructive evaluation and signal processing for diagnosis of historic heritage buildings

[EN] In this work, signal processing techniques are combined with non-destructive evaluation (NDE) to evaluate the capability for detecting defects in historic walls. To join this aim, ashlar masonry walls of 3x2x0.2m have been made at laboratory facilities with controlled and localized defects. These scale walls have been inspected by means ultrasound and ground penetrating radar (GPR) with loads of different weights (0Tn, 10Tn, 50Tn and 80Tn). The ultrasonic and GPR signals provided tomographies that have been improved by means processing techniques. Related to ultrasonic tomographies, kriging algorithm have been implemented for visualization improvement. By the other hand, novelty differential tomographies have demonstrated their sensibility to defects. Related to GPR, different algorithms have been developed to improve the tomographies: elimination of the background noise, depth resolution enhancing and automatic detection and correction of hyperbolas due to radiation pattern of the antenna. Finally, it is concluded the added value of signal processing applied to NDE for the detection of defects in historic walls.This work has been supported by the Generalitat Valenciana under grant PROMETEO/2010/040Gosálbez Castillo, J.; Salazar Afanador, A.; Safont Armero, G.; Bosch Roig, I.; Miralles Ricós, R.; Vergara Domínguez, L.; Albert Pérez, V. (2011). Application of non-destructive evaluation and signal processing for diagnosis of historic heritage buildings. Waves. 3(1):107-116. http://hdl.handle.net/10251/56157S1071163

SEÑALES Y SISTEMAS. TEORÍA Y PROBLEMAS

El presente libro es una guía para el estudio de los conceptos básicos de la teoría de señales y sistemas. Aunque con cierta orientación hacia el ámbito de las Telecomunicaciones, puede resultar de interés en cualquier otro ámbito que utilice las señales y los sistemas como elementos básicos de modelado. Su orientación es principalmente práctica y está dirigida a la resolución de problemas introduciendo previamente los conceptos teóricos necesarios. De esta forma y en líneas generales, el objetivo es dotar al lector de un material básico de consulta que le oriente por el mundo de las señales y su interacción con los sistemas, tanto desde el punto de vista continuo y discreto, como desde el punto de vista temporal y otros dominios (frecuencial, Laplace, o Z). El libro presenta teoría, cuestiones y problemas, de forma ordenada en cuatro capítulos, los dos primeros corresponden a la parte continua o analógica, mientras que los dos últimos corresponden a la parte discreta o digital.Bosch Roig, I.; Gosálbez Castillo, J.; Miralles Ricós, R.; Vergara Domínguez, L. (2015). SEÑALES Y SISTEMAS. TEORÍA Y PROBLEMAS. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/67081EDITORIA