Enhanced numerical method for the design of 3D-printed holographic acoustic lenses for aberration correction of single-element transcranial focused ultrasound

[EN] 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.This work was partially supported by the Spanish Ministerio de Economia y Empresa under Project TEC2015-68076-R. The authors thank Jose Sepulveda, director of Asociacion I2 CV, for his important input and scientific support.Ferri García, M.; Bravo, JM.; Redondo, J.; Sánchez Pérez, JV. (2019). Enhanced numerical method for the design of 3D-printed holographic acoustic lenses for aberration correction of single-element transcranial focused ultrasound. Ultrasound in Medicine & Biology. 45(3):867-884. https://doi.org/10.1016/j.ultrasmedbio.2018.10.022S86788445

Integrated Photogrammetric-Acoustic Technique for Qualitative Analysis of the Performance of Acoustic Screens in Sandy Soils

[EN] 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.Bravo, JM.; Buchón Moragues, FF.; Redondo, J.; Ferri García, M.; Sánchez Pérez, JV. (2019). Integrated Photogrammetric-Acoustic Technique for Qualitative Analysis of the Performance of Acoustic Screens in Sandy Soils. Sensors. 19(22):1-17. https://doi.org/10.3390/s19224881S1171922Castiñeira-Ibañez, S., Rubio, C., & Sánchez-Pérez, J. V. (2015). Environmental noise control during its transmission phase to protect buildings. Design model for acoustic barriers based on arrays of isolated scatterers. Building and Environment, 93, 179-185. doi:10.1016/j.buildenv.2015.07.002Fredianelli, L., Del Pizzo, A., & Licitra, G. (2019). Recent Developments in Sonic Crystals as Barriers for Road Traffic Noise Mitigation. Environments, 6(2), 14. doi:10.3390/environments6020014Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0Morandi, F., Miniaci, M., Marzani, A., Barbaresi, L., & Garai, M. (2016). Standardised acoustic characterisation of sonic crystals noise barriers: Sound insulation and reflection properties. Applied Acoustics, 114, 294-306. doi:10.1016/j.apacoust.2016.07.028Castiñeira-Ibáñez, S., Rubio, C., Romero-García, V., Sánchez-Pérez, J. V., & García-Raffi, L. M. (2012). Design, Manufacture and Characterization of an Acoustic Barrier Made of Multi-Phenomena Cylindrical Scatterers Arranged in a Fractal-Based Geometry. Archives of Acoustics, 37(4), 455-462. doi:10.2478/v10168-012-0057-9Sanchez-Perez, J. V., Castineira-Ibanez, S., Romero-Garcia, V., & Garcia-Raffi, L. M. (2015). PERIODIC SYSTEMS AS ROAD TRAFFIC NOISE REDUCING DEVICES: PROTOTYPE AND STANDARDIZATION. Environmental Engineering and Management Journal, 14(12), 2759-2769. doi:10.30638/eemj.2015.293Wang, Y.-F., Wang, Y.-S., & Laude, V. (2015). Wave propagation in two-dimensional viscoelastic metamaterials. Physical Review B, 92(10). doi:10.1103/physrevb.92.104110Wang, Y.-F., Liang, J.-W., Chen, A.-L., Wang, Y.-S., & Laude, V. (2019). Wave propagation in one-dimensional fluid-saturated porous metamaterials. Physical Review B, 99(13). doi:10.1103/physrevb.99.134304Valkenburg, R. J., & McIvor, A. M. (1998). Accurate 3D measurement using a structured light system. Image and Vision Computing, 16(2), 99-110. doi:10.1016/s0262-8856(97)00053-xHui, Z., Liyan, Z., Hongtao, W., & Jianfu, C. (2009). Surface Measurement Based on Instantaneous Random Illumination. Chinese Journal of Aeronautics, 22(3), 316-324. doi:10.1016/s1000-9361(08)60105-3McPherron, S. P., Gernat, T., & Hublin, J.-J. (2009). Structured light scanning for high-resolution documentation of in situ archaeological finds. Journal of Archaeological Science, 36(1), 19-24. doi:10.1016/j.jas.2008.06.028Bruno, F., Bianco, G., Muzzupappa, M., Barone, S., & Razionale, A. V. (2011). Experimentation of structured light and stereo vision for underwater 3D reconstruction. ISPRS Journal of Photogrammetry and Remote Sensing, 66(4), 508-518. doi:10.1016/j.isprsjprs.2011.02.009Bertani, D. (1995). High-resolution optical topography applied to ancient painting diagnostics. Optical Engineering, 34(4), 1219. doi:10.1117/12.196545Buchón-Moragues, F., Bravo, J., Ferri, M., Redondo, J., & Sánchez-Pérez, J. (2016). Application of Structured Light System Technique for Authentication of Wooden Panel Paintings. Sensors, 16(6), 881. doi:10.3390/s16060881Arias, P., Herráez, J., Lorenzo, H., & Ordóñez, C. (2005). Control of structural problems in cultural heritage monuments using close-range photogrammetry and computer methods. Computers & Structures, 83(21-22), 1754-1766. doi:10.1016/j.compstruc.2005.02.018Rocchini, C., Cignoni, P., Montani, C., Pingi, P., & Scopigno, R. (2001). A low cost 3D scanner based on structured light. Computer Graphics Forum, 20(3), 299-308. doi:10.1111/1467-8659.00522Bianchi, M. G., Casula, G., Cuccuru, F., Fais, S., Ligas, P., & Ferrara, C. (2018). Three-dimensional imaging from laser scanner, photogrammetric and acoustic non-destructive techniques in the characterization of stone building materials. Advances in Geosciences, 45, 57-62. doi:10.5194/adgeo-45-57-2018Alvarez, L., Moreno, H., Segales, A., Pham, T., Pillar-Little, E., & Chilson, P. (2018). Merging Unmanned Aerial Systems (UAS) Imagery and Echo Soundings with an Adaptive Sampling Technique for Bathymetric Surveys. Remote Sensing, 10(9), 1362. doi:10.3390/rs10091362Miller, B. S., Wotherspoon, S., Rankin, S., Calderan, S., Leaper, R., & Keating, J. L. (2018). Estimating drift of directional sonobuoys from acoustic bearings. The Journal of the Acoustical Society of America, 143(1), EL25-EL30. doi:10.1121/1.5020621Zhang, D., Li, S., Bai, X., Yang, Y., & Chu, Y. (2019). Experimental Study on Mechanical Properties, Energy Dissipation Characteristics and Acoustic Emission Parameters of Compression Failure of Sandstone Specimens Containing En Echelon Flaws. Applied Sciences, 9(3), 596. doi:10.3390/app9030596Hartley, R. I., & Schaffalitzky, F. (2009). Reconstruction from Projections Using Grassmann Tensors. International Journal of Computer Vision, 83(3), 274-293. doi:10.1007/s11263-009-0225-1Ahmadabadian, A. H., Robson, S., Boehm, J., Shortis, M., Wenzel, K., & Fritsch, D. (2013). A comparison of dense matching algorithms for scaled surface reconstruction using stereo camera rigs. ISPRS Journal of Photogrammetry and Remote Sensing, 78, 157-167. doi:10.1016/j.isprsjprs.2013.01.015Olague, G., & Dunn, E. (2007). Development of a practical photogrammetric network design using evolutionary computing. The Photogrammetric Record, 22(117), 22-38. doi:10.1111/j.1477-9730.2007.00403.xHirschmuller, H. (2008). Stereo Processing by Semiglobal Matching and Mutual Information. IEEE Transactions on Pattern Analysis and Machine Intelligence, 30(2), 328-341. doi:10.1109/tpami.2007.1166Chen, Y., & Wang, L. (2014). Periodic co-continuous acoustic metamaterials with overlapping locally resonant and Bragg band gaps. Applied Physics Letters, 105(19), 191907. doi:10.1063/1.4902129Kaina, N., Causier, A., Bourlier, Y., Fink, M., Berthelot, T., & Lerosey, G. (2017). Slow waves in locally resonant metamaterials line defect waveguides. Scientific Reports, 7(1). doi:10.1038/s41598-017-15403-8Cummer, S. A., Christensen, J., & Alù, A. (2016). Controlling sound with acoustic metamaterials. Nature Reviews Materials, 1(3). doi:10.1038/natrevmats.2016.1Sigalas, M. M., & Economou, E. N. (1992). Elastic and acoustic wave band structure. Journal of Sound and Vibration, 158(2), 377-382. doi:10.1016/0022-460x(92)90059-7Sánchez-Pérez, J. V., Caballero, D., Mártinez-Sala, R., Rubio, C., Sánchez-Dehesa, J., Meseguer, F., … Gálvez, F. (1998). Sound Attenuation by a Two-Dimensional Array of Rigid Cylinders. Physical Review Letters, 80(24), 5325-5328. doi:10.1103/physrevlett.80.5325Sanchez-Perez, J. V., Rubio, C., Martinez-Sala, R., Sanchez-Grandia, R., & Gomez, V. (2002). Acoustic barriers based on periodic arrays of scatterers. Applied Physics Letters, 81(27), 5240-5242. doi:10.1063/1.153311

Normal incidence sound insulation provided by Sonic Crystal Acoustic Screens made from rigid scatterers - assessment of different simulation methods

[EN] Sonic crystal acoustic screens have been in progressive research and development in the last two decades as a technical solution for mitigating traffic noise. Their behaviour is quite different from that observed in classical barriers, with the latter being based on physically blocking the direct sound propagation path (only allowing diffracted noise to reach sensible receivers), and sonic crystals providing attenuation efficiency based on the creation of "band-gaps" at specific frequency ranges, due to the Bragg's interference phenomenon. The distinct physical mechanisms of these two types of noise barriers complicates the use of classical simplified or even numerical models developed for traditional barriers to simulate and predict the attenuation performance of a sonic crystal, and alternative methods become thus required. In the acoustics scientific literature, several authors have proposed estimation and simulation methods based on different numerical tools to predict the sound insulation provided by these new noise abatement solutions. This paper presents a comparative evaluation of some of these methods, with emphasis on the assessment of their accuracy versus memory usage in order to determine which one is the most suitable for optimization methodologies in the design of new devices with improved acoustic performance.M.P.P.T is grateful for the support of pre-doctoral Grant by the "Ministerio de Ciencia, Innovacion y Universidades. Agencia Estatal de Investigacion" of Spain through reference no. DI-15-08100. This work has been supported by the Ministerio de Ciencia, Innovacion y Universidades, Spain, under grant RTI2018-096904-B-I00. This work was developed within the scope of the project with reference POCI-01-0247-FEDER-033691 - HLS -Hybrid Log Shield, supported by FEDER funds, through Portugal-2020 (PT2020) Programme, within the scope of SII&DT System, and by POCI Programme. This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020.Peiró-Torres, M.; Ferri García, M.; Godinho, LM.; Amado-Mendes, P.; Vea-Folch, FJ.; Redondo, J. (2021). Normal incidence sound insulation provided by Sonic Crystal Acoustic Screens made from rigid scatterers - assessment of different simulation methods. Acta Acustica. 5:1-10. https://doi.org/10.1051/aacus/2021021110

Sonic Crystals Acoustic Screens and Diffusers

[EN] This article presents the use of advanced tools applied to the design of devices that can solve specific acoustic problems, improving the already existing devices based on classic technologies. Specifically, we have used two different configurations of a material called Sonic Crystals, which is formed by arrays of acoustic scatterers, to obtain acoustic screens with high diffusion properties by means of an optimization process. This design procedure has been carried out using a multiobjective evolutionary algorithm along to an acoustic simulation model developed with the numerical method called Finite Difference Time Domain. The results obtained are discussed in terms of both the acoustic performance and the robustness of the devices achieved.This work was partially supported by the Spanish "Ministerio de Economia y Competitividad" under the project TEC2015-68076-R.Peiró-Torres, MDP.; Parrilla-Navarro, MJ.; Ferri García, M.; Bravo, JM.; Sánchez Pérez, JV.; Redondo, J. (2019). Sonic Crystals Acoustic Screens and Diffusers. Applied Acoustics. 148:399-408. https://doi.org/10.1016/j.apacoust.2019.01.004S39940814

On the Evaluation of the Suitability of the Materials Used to 3D Print Holographic Acoustic Lenses to Correct Transcranial Focused Ultrasound Aberrations

[EN] The correction of transcranial focused ultrasound aberrations is a relevant topic for enhancing various non-invasive medical treatments. Presently, the most widely accepted method to improve focusing is the emission through multi-element phased arrays; however, a new disruptive technology, based on 3D printed holographic acoustic lenses, has recently been proposed, overcoming the spatial limitations of phased arrays due to the submillimetric precision of the latest generation of 3D printers. This work aims to optimize this recent solution. Particularly, the preferred acoustic properties of the polymers used for printing the lenses are systematically analyzed, paying special attention to the effect of p-wave speed and its relationship to the achievable voxel size of 3D printers. Results from simulations and experiments clearly show that, given a particular voxel size, there are optimal ranges for lens thickness and p-wave speed, fairly independent of the emitted frequency, the transducer aperture, or the transducer-target distance.This work was partially supported by the Spanish "Ministerio de Economia y Competitividad" under the projects RTI2018-096904-B-I00 and TEC2016-80976-R. N.J. and S.J. acknowledge financial support from Generalitat Valenciana through Grants No. APOSTD/2017/042, No. ACIF/2017/045, and No. GV/2018/11. F.C. acknowledges financial support from Agencia Valenciana de la Innovacio through Grants No. INNCON00/18/9 and INNVAL10/19/016 and Generalitat Valenciana and European Regional Development Fund (Grant No. IDIFEDER/2018/022).Ferri García, M.; Bravo Plana-Sala, JM.; Redondo, J.; Jiménez-Gambín, S.; Jimenez, N.; Camarena Femenia, F.; Sánchez-Pérez, JV. (2019). On the Evaluation of the Suitability of the Materials Used to 3D Print Holographic Acoustic Lenses to Correct Transcranial Focused Ultrasound Aberrations. Polymers. 11(9):1-25. https://doi.org/10.3390/polym11091521S125119Ochiai, Y., Hoshi, T., & Rekimoto, J. (2014). Pixie dust. ACM Transactions on Graphics, 33(4), 1-13. doi:10.1145/2601097.2601118Kuo, L.-W., Chiu, L.-C., Lin, W.-L., Chen, J.-J., Dong, G.-C., Chen, S.-F., & Chen, G.-S. (2018). Development of an MRI-Compatible High-Intensity Focused Ultrasound Phased Array Transducer Dedicated for Breast Tumor Treatment. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 65(8), 1423-1432. doi:10.1109/tuffc.2018.2841418Xie, Y., Wang, W., Chen, H., Konneker, A., Popa, B.-I., & Cummer, S. A. (2014). Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface. Nature Communications, 5(1). doi:10.1038/ncomms6553Xie, Y., Shen, C., Wang, W., Li, J., Suo, D., Popa, B.-I., … Cummer, S. A. (2016). Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array. Scientific Reports, 6(1). doi:10.1038/srep35437Brown, M. D., Nikitichev, D. I., Treeby, B. E., & Cox, B. T. (2017). Generating arbitrary ultrasound fields with tailored optoacoustic surface profiles. Applied Physics Letters, 110(9), 094102. doi:10.1063/1.4976942Maimbourg, G., Houdouin, A., Deffieux, T., Tanter, M., & Aubry, J.-F. (2018). 3D-printed adaptive acoustic lens as a disruptive technology for transcranial ultrasound therapy using single-element transducers. Physics in Medicine & Biology, 63(2), 025026. doi:10.1088/1361-6560/aaa037Zhang, J., Yang, Y., Zhu, B., Li, X., Jin, J., Chen, Z., … Zhou, Q. (2018). Multifocal point beam forming by a single ultrasonic transducer with 3D printed holograms. Applied Physics Letters, 113(24), 243502. doi:10.1063/1.5058079Ferri, M., Bravo, J. M., Redondo, J., & Sánchez-Pérez, J. V. (2019). Enhanced Numerical Method for the Design of 3-D-Printed Holographic Acoustic Lenses for Aberration Correction of Single-Element Transcranial Focused Ultrasound. Ultrasound in Medicine & Biology, 45(3), 867-884. doi:10.1016/j.ultrasmedbio.2018.10.022Jiménez-Gambín, S., Jiménez, N., Benlloch, J. M., & Camarena, F. (2019). Holograms to Focus Arbitrary Ultrasonic Fields through the Skull. Physical Review Applied, 12(1). doi:10.1103/physrevapplied.12.014016Clement, G. T., White, J., & Hynynen, K. (2000). Investigation of a large-area phased array for focused ultrasound surgery through the skull. Physics in Medicine and Biology, 45(4), 1071-1083. doi:10.1088/0031-9155/45/4/319Elias, W. J., Huss, D., Voss, T., Loomba, J., Khaled, M., Zadicario, E., … Wintermark, M. (2013). A Pilot Study of Focused Ultrasound Thalamotomy for Essential Tremor. New England Journal of Medicine, 369(7), 640-648. doi:10.1056/nejmoa1300962Burgess, A., Ayala-Grosso, C. A., Ganguly, M., Jordão, J. F., Aubert, I., & Hynynen, K. (2011). Targeted Delivery of Neural Stem Cells to the Brain Using MRI-Guided Focused Ultrasound to Disrupt the Blood-Brain Barrier. PLoS ONE, 6(11), e27877. doi:10.1371/journal.pone.0027877Choi, J. J., Pernot, M., Small, S. A., & Konofagou, E. E. (2007). Noninvasive, transcranial and localized opening of the blood-brain barrier using focused ultrasound in mice. Ultrasound in Medicine & Biology, 33(1), 95-104. doi:10.1016/j.ultrasmedbio.2006.07.018Aubry, J.-F., Tanter, M., Pernot, M., Thomas, J.-L., & Fink, M. (2003). Experimental demonstration of noninvasive transskull adaptive focusing based on prior computed tomography scans. The Journal of the Acoustical Society of America, 113(1), 84-93. doi:10.1121/1.1529663Jolesz, F. A., & McDannold, N. J. (2014). Magnetic Resonance–Guided Focused Ultrasound. Neurologic Clinics, 32(1), 253-269. doi:10.1016/j.ncl.2013.07.008Fry, F. J., & Goss, S. A. (1980). Further studies of the transkull transmission of an intense focused ultrasonic beam: Lesion production at 500 kHz. Ultrasound in Medicine & Biology, 6(1), 33-38. doi:10.1016/0301-5629(80)90061-7Coluccia, D., Figueiredo, C. A., Wu, M. Y., Riemenschneider, A. N., Diaz, R., Luck, A., … Rutka, J. T. (2018). Enhancing glioblastoma treatment using cisplatin-gold-nanoparticle conjugates and targeted delivery with magnetic resonance-guided focused ultrasound. Nanomedicine: Nanotechnology, Biology and Medicine, 14(4), 1137-1148. doi:10.1016/j.nano.2018.01.021McDannold, N., Clement, G. T., Black, P., Jolesz, F., & Hynynen, K. (2010). Transcranial Magnetic Resonance Imaging– Guided Focused Ultrasound Surgery of Brain Tumors. Neurosurgery, 66(2), 323-332. doi:10.1227/01.neu.0000360379.95800.2fMeng, Y., Volpini, M., Black, S., Lozano, A. M., Hynynen, K., & Lipsman, N. (2017). Focused ultrasound as a novel strategy for Alzheimer disease therapeutics. Annals of Neurology, 81(5), 611-617. doi:10.1002/ana.24933Magara, A., Bühler, R., Moser, D., Kowalski, M., Pourtehrani, P., & Jeanmonod, D. (2014). First experience with MR-guided focused ultrasound in the treatment of Parkinson’s disease. Journal of Therapeutic Ultrasound, 2(1). doi:10.1186/2050-5736-2-11Hynynen, K., McDannold, N., Vykhodtseva, N., & Jolesz, F. A. (2001). Noninvasive MR Imaging–guided Focal Opening of the Blood-Brain Barrier in Rabbits. Radiology, 220(3), 640-646. doi:10.1148/radiol.2202001804Kinoshita, M., McDannold, N., Jolesz, F. A., & Hynynen, K. (2006). Noninvasive localized delivery of Herceptin to the mouse brain by MRI-guided focused ultrasound-induced blood-brain barrier disruption. Proceedings of the National Academy of Sciences, 103(31), 11719-11723. doi:10.1073/pnas.0604318103Baseri, B., Choi, J. J., Deffieux, T., Samiotaki, G., Tung, Y.-S., Olumolade, O., … Konofagou, E. E. (2012). Activation of signaling pathways following localized delivery of systemically administered neurotrophic factors across the blood–brain barrier using focused ultrasound and microbubbles. Physics in Medicine and Biology, 57(7), N65-N81. doi:10.1088/0031-9155/57/7/n65Alonso, A., Reinz, E., Leuchs, B., Kleinschmidt, J., Fatar, M., Geers, B., … Meairs, S. (2013). Focal Delivery of AAV2/1-transgenes Into the Rat Brain by Localized Ultrasound-induced BBB Opening. Molecular Therapy - Nucleic Acids, 2, e73. doi:10.1038/mtna.2012.64Wang, S., Olumolade, O. O., Sun, T., Samiotaki, G., & Konofagou, E. E. (2014). Noninvasive, neuron-specific gene therapy can be facilitated by focused ultrasound and recombinant adeno-associated virus. Gene Therapy, 22(1), 104-110. doi:10.1038/gt.2014.91Guthkelch, A. N., Carter, L. P., Cassady, J. R., Hynynen, K. H., Iacono, R. P., Johnson, P. C., … Steal, B. (1991). Treatment of malignant brain tumors with focused ultrasound hyperthermia and radiation: results of a phase I trial. Journal of Neuro-Oncology, 10(3). doi:10.1007/bf00177540Marquet, F., Tung, Y.-S., Teichert, T., Ferrera, V. P., & Konofagou, E. E. (2012). Feasibility study of a single-element transcranial focused ultrasound system for blood-brain barrier opening. doi:10.1063/1.4757340Thomas, J.-L., & Fink, M. A. (1996). Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 43(6), 1122-1129. doi:10.1109/58.542055Sun, J., & Hynynen, K. (1998). Focusing of therapeutic ultrasound through a human skull: A numerical study. The Journal of the Acoustical Society of America, 104(3), 1705-1715. doi:10.1121/1.424383Clement, G. T., & Hynynen, K. (2002). A non-invasive method for focusing ultrasound through the human skull. Physics in Medicine and Biology, 47(8), 1219-1236. doi:10.1088/0031-9155/47/8/301Marsac, L., Chauvet, D., La Greca, R., Boch, A.-L., Chaumoitre, K., Tanter, M., & Aubry, J.-F. (2017). Ex vivo optimisation of a heterogeneous speed of sound model of the human skull for non-invasive transcranial focused ultrasound at 1 MHz. International Journal of Hyperthermia, 33(6), 635-645. doi:10.1080/02656736.2017.1295322Pichardo, S., Sin, V. W., & Hynynen, K. (2010). Multi-frequency characterization of the speed of sound and attenuation coefficient for longitudinal transmission of freshly excised human skulls. Physics in Medicine and Biology, 56(1), 219-250. doi:10.1088/0031-9155/56/1/014Connor, C. W., & Hynynen, K. (2004). Patterns of Thermal Deposition in the Skull During Transcranial Focused Ultrasound Surgery. IEEE Transactions on Biomedical Engineering, 51(10), 1693-1706. doi:10.1109/tbme.2004.831516Connor, C. W., Clement, G. T., & Hynynen, K. (2002). A unified model for the speed of sound in cranial bone based on genetic algorithm optimization. Physics in Medicine and Biology, 47(22), 3925-3944. doi:10.1088/0031-9155/47/22/302Clement, G. T., White, P. J., & Hynynen, K. (2004). Enhanced ultrasound transmission through the human skull using shear mode conversion. The Journal of the Acoustical Society of America, 115(3), 1356-1364. doi:10.1121/1.1645610Pinton, G., Aubry, J.-F., Bossy, E., Muller, M., Pernot, M., & Tanter, M. (2011). Attenuation, scattering, and absorption of ultrasound in the skull bone. Medical Physics, 39(1), 299-307. doi:10.1118/1.3668316Hughes, A., Huang, Y., Pulkkinen, A., Schwartz, M. L., Lozano, A. M., & Hynynen, K. (2016). A numerical study on the oblique focus in MR-guided transcranial focused ultrasound. Physics in Medicine and Biology, 61(22), 8025-8043. doi:10.1088/0031-9155/61/22/8025Jiménez, N., Camarena, F., Redondo, J., Sánchez-Morcillo, V., Hou, Y., & Konofagou, E. E. (2016). 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The Journal of the Acoustical Society of America, 124(4), 2406-2420. doi:10.1121/1.2967836O’Neil, H. T. (1949). Theory of Focusing Radiators. The Journal of the Acoustical Society of America, 21(5), 516-526. doi:10.1121/1.1906542Ultrasonic Test Equipment. HIGH Z Ultrasonic Couplanthttp://www.webcitation.org/78VUxlDe

Application of structured light system technique for authentication of wooden panel paintings

[EN] This paper presents a new application of photogrammetric techniques for protecting cultural heritage. The accuracy of the method and the fact that it can be used to carry out different tests without contact between the sample and the instruments can make this technique very useful for authenticating and cataloging artworks. The application focuses on the field of pictorial artworks, and wooden panel paintings in particular. In these works, the orography formed by the brushstrokes can be easily digitalized using a photogrammetric technique, called Structured Light System, with submillimeter accuracy. Thus, some of the physical characteristics of the brushstrokes, like minimum and maximum heights or slopes become a fingerprint of the painting. We explain in detail the general principles of the Structured Light System Technique and the specific characteristics of the commercial set-up used in this work. Some experiments are carried out on a sample painted by us to check the accuracy limits of the technique and to propose some tests that can help to stablish a methodology for authentication purposes. Finally, some preliminary results obtained on a real pictorial artwork are presented, providing geometrical information of its metric features as an example of the possibilities of this applicationThis work was financially supported by Generalitat Valenciana through Contract No. AICO/2015/005.Buchón Moragues, FF.; Bravo, JM.; Ferri García, M.; Redondo, J.; Sánchez Pérez, JV. (2016). Application of structured light system technique for authentication of wooden panel paintings. Sensors. 16(881):1-10. https://doi.org/10.3390/s16060881S1101688

Explicit finite-difference time-domain scheme for the simulation of 1-3 piezoelectric effect in axisymmetrical configurations

[EN] Numerical simulations are useful in the processes of design, development and optimization of transducers for non-destructive testing. In this work, a three-dimensional velocity-stress finite-difference model is presented for the elastic wave propagation in the piezoelectric substrate of a transducer excited by applying an impulsive voltage signal to the transducer electrodes. The allocation of the stress, velocity and electric field components on a staggered grid leads to a stable scheme. The different time scales of both mechanical and electromagnetic waves have leaded previous FDTD models to choose between significant physical simplifications or complicated implicit equations. The model presented here is explicit in all its time domain equations, contains only first order derivatives and is centered in time and space. The results of simulations show remarkable accuracy and stability for the different transducers studied. © 2012 Elsevier B.V.The authors want to thank Miquel Ardid, Víctor Sánchez and Bernardino Roig for their cooperation and fruitful discussions. This study was supported by the Programa de Apoyo a la Investigación y Desarrollo PAID-06-10-002-295 of Universidad Politécnica de Valencia.Ferri García, M.; Camarena Femenia, F.; Redondo, J.; Picó Vila, R.; Avis, MR. (2012). Explicit finite-difference time-domain scheme for the simulation of 1-3 piezoelectric effect in axisymmetrical configurations. Wave Motion. 49(6):569-584. https://doi.org/10.1016/j.wavemoti.2012.03.007S56958449

Simulación numérica de una cerámica piezoeléctrica

[EN] In this paper, a mathematical model describing the dynamic behavior of a commercial piezoelectric ceramic, vibrating in thickness, is presented. This model solves, by finite differences, the piezoelectric equations which relate he mechanical and electrical phenomena produced in this kind of material. The behavior in time domain of some physical variables, as the electric field and particle velocity, is simulated too. In addition, we have implemented a GUI in Matlab that allows simple and affordable simulations for all users. The implemented interface provides two kind of study: Broadband and single frequency excitation. The output parameters, obtained after time domain simulation, are piezoelectric constants of the ceramic and the electric response in frequency domain, i.e. admittance and impedance curves. The results allow predicting vibration modes, electrical response and understanding the effect of piezoelectricity on the mechanical response.[ES] En este trabajo se presenta un modelo matemático que describe el comportamiento dinámico de una cerámica piezoeléctrica comercial vibrando en modo espesor. Dicho modelo resuelve, mediante diferencias finitas, las ecuaciones piezoeléctricas que relacionan los fenómenos mecánicos y eléctricos que se producen en este tipo de materiales, y simula el comportamiento de algunas variables físicas puntuales -como campo eléctrico o velocidad de partícula- en el dominio de tiempo. Asimismo, se ha implementado un entorno gráfico en Matlab que permite realizar las simulaciones de forma sencilla y asequible a todos los usuarios. Esta interfaz contempla dos tipos de estudio: excitación de la cerámica en banda ancha y excitación a una sola frecuencia. Como valores de salida el programa facilita, una vez finalizada la simulación de las variables dependientes del tiempo, los distintos parámetros piezoeléctricos de la cerámica y su respuesta eléctrica en el dominio de la frecuencia (curvas de admitancia e impedancia). Los resultados obtenidos permiten, además de predecir los modos propios de vibración y la respuesta eléctrica, comprender el efecto de piezoelectricidad en la respuesta mecánica de un medio material.Este trabajo ha sido financiado por la Universitat Politècnica de València bajo los proyectos PAID 06-10-002-295 y PAID 05-11-002-340González-Salido, N.; Ferri, M.; Jiménez, N.; Camarena, F.; Picó, R.; Redondo, J.; Roig, B. (2013). Simulación numérica de una cerámica piezoeléctrica. Modelling in Science Education and Learning. 6(3):131-144. doi:10.4995/msel.2013.1990SWORD13114463W. G. Hankel. Uber die aktinound piezoelektrischen eigenschaften des bergkrystalles und ihre beziehung zu den thermoelektrischen. Abh. Sächs, 12:457 (1881).Arnau Vives, A. (Ed.). (2004). Piezoelectric Transducers and Applications. doi:10.1007/978-3-662-05361-4T. F. Hueter, R. H. Bolt. Sonics. John Wiley and Sons, Inc, New York, (1955).Ferri, M., Camarena, F., Redondo, J., Picó, R., & Avis, M. R. (2012). Explicit finite-difference time-domain scheme for the simulation of 1-3 piezoelectric effect in axisymmetrical configurations. Wave Motion, 49(6), 569-584. doi:10.1016/j.wavemoti.2012.03.00

Expansion cone for the 3-inch PMTs of the KM3NeT optical modules

[EN] Detection of high-energy neutrinos from distant astrophysical sources will open a new window on the Universe. The detection principle exploits the measurement of Cherenkov light emitted by charged particles resulting from neutrino interactions in the matter containing the telescope. A novel multi-PMT digital optical module (DOM) was developed to contain 31 3-inch photomultiplier tubes (PMTs). In order to maximize the detector sensitivity, each PMT will be surrounded by an expansion cone which collects photons that would otherwise miss the photocathode. Results for various angles of incidence with respect to the PMT surface indicate an increase in collection efficiency by 30% on average for angles up to 45 degrees with respect to the perpendicular. Ray-tracing calculations could reproduce the measurements, allowing to estimate an increase in the overall photocathode sensitivity, integrated over all angles of incidence, by 27% (for a single PMT). Prototype DOMs, being built by the KM3NeT consortium, will be equipped with these expansion cones.This work is supported through the EU, FP6 Contract no. 011937, FP7 grant agreement no. 212252, and the Dutch Ministry of Education, Culture and Science.Adrián Martínez, S.; Ageron, M.; Aguilar, JA.; Aharonian, F.; Aiello, S.; Albert, A.; Alexandri, M.... (2013). Expansion cone for the 3-inch PMTs of the KM3NeT optical modules. Journal of Instrumentation. 8(3):1-19. https://doi.org/10.1088/1748-0221/8/03/T03006S1198