Redirection and Splitting of Sound Waves by a Periodic Chain of Thin Perforated Cylindrical Shells

[EN] The scattering of sound by finite and infinite chains of equally spaced perforated metallic cylindrical shells in an ideal (inviscid) and viscous fluid is theoretically studied using rigorous analytical and numerical approaches. Because of perforations, a chain of thin shells is practically transparent for sound within a wide range of frequencies. It is shown that strong scattering and redirection of sound by 90° may occur only for a discrete set of frequencies (Wood¿s anomalies) where the leaky eigenmodes are excited. The spectrum of eigenmodes consists of antisymmetric and symmetric branches with normal and anomalous dispersion, respectively. The antisymmetric eigenmode turns out to be a deaf mode, since it cannot be excited at normal incidence. However, at slightly oblique incidence, both modes can be resonantly excited at different but close frequencies. The symmetric mode, due to its anomalous dispersion, scatters sound in the ¿wrong¿ direction. This property may find an application for the splitting of the two resonant harmonics of the incoming signal into two beams propagating along the chain in the opposite directions. A chain of perforated cylinders may also be used as a passive antenna that detects the direction to the incoming signal by measuring the frequencies of the waves excited in the chain. Calculations are presented for aluminum shells in viscous air where the effects of anomalous scattering, redirection, and signal splitting are well manifested.A. K. acknowledges support from Programa de Apoyo a la Investigacion y Desarrollo (PAID-02-15) de la Universitat Politecnica de Valencia. A. B., F. C., and J. S.-D. acknowledge the support by the Ministerio de Economia y Competitividad of the Spanish government and the European Union Fondo Europeo de Desarrollo Regional (FEDER) through Project No. TEC2014-53088-C3-1-R. The authors are thankful to Michael R. Haberman for fruitful discussion regarding possible applications of the periodic chain of a perforated shell in the processing of acoustic signals.Bozhko, A.; Sánchez-Dehesa Moreno-Cid, J.; Cervera Moreno, FS.; Krokhin, A. (2017). Redirection and Splitting of Sound Waves by a Periodic Chain of Thin Perforated Cylindrical Shells. Physical Review Applied. 7(6):064034-1-064034-13. doi:10.1103/PhysRevApplied.7.064034S064034-1064034-137

Experimental evidence of the Poisson-like effect for flexural waves in thin metallic plates

[EN] This Letter reports the feasibility of a structure specifically designed for the control of flexural waves propagating in thin perforated plates. The structure, here denominated as a redirector device, consists of a square array of free holes that splits the impinging beam and transmits sideways their vibrational energy. This behavior is known as a Poisson-like effect, and it was theoretically described in different acoustic structures. This effect is experimentally demonstrated for flexural waves excited in an aluminum perforated plate, and it is explained in terms of a physical mechanism different to that reported for acoustic waves interacting with thin hollow cylinders embedded in water. In addition, a collimator device based also in free holes is designed and validated with the purpose of providing the beam impinging the redirector device. The measurements indicate that the amount of redirected energy is strongly enhanced when a barrier of two-beam resonators is added at the rear side of the redirector. All the designs are validated by an experimental setup employing 1¿mm thick aluminum plates.This research was partially supported by Grant No. PID2020112759GB-I00 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe." J.S.-D. acknowledges the "Proyecto interno" supported by the Universitat Polite`cnica de Valencia. A.F. is supported through the Programa de Apoyo para la Investigaci~on y Desarrollo of the Universitat Polite`cnica de Vale`ncia under Grant Nos. PAID-01-20 and 21589. J.S.-D. and P.G. acknowledge useful conversations with Johan Christensen.Sánchez-Dehesa Moreno-Cid, J.; Gao, P.; Cervera Moreno, FS.; Broatch, A.; Garcia Tiscar, J.; Felgueroso-Rodríguez, A. (2022). Experimental evidence of the Poisson-like effect for flexural waves in thin metallic plates. Applied Physics Letters. 120(9). https://doi.org/10.1063/5.0080450094102120

Majorana-like Zero Modes in Kekule Distorted Sonic Lattices

[EN] Topological phases have recently been realized in bosonic systems. The associated boundary modes between regions of distinct topology have been used to demonstrate robust waveguiding, protected from defects by the topology of the surrounding bulk. A related type of topologically protected state that is not propagating but is bound to a defect has not been demonstrated to date in a bosonic setting. Here we demonstrate numerically and experimentally that an acoustic mode can be topologically bound to a vortex fabricated in a two-dimensional, Kekul¿e-distorted triangular acoustic lattice. Such lattice realizes an acoustic analog of the Jackiw-Rossi mechanism that topologically binds a bound state in a p-wave superconductor vortex. The acoustic bound state is thus a bosonic analog of a Majorana bound state, where the two valleys replace particle and hole components. We numerically show that it is topologically protected against arbitrary symmetry-preserving local perturbations, and remains pinned to the Dirac frequency of the unperturbed lattice regardless of parameter variations. We demonstrate our prediction experimentally by 3D printing the vortex pattern in a plastic matrix and measuring the spectrum of the acoustic response of the device. Despite viscothermal losses, the measured topological resonance remains robust, with its frequency closely matching our simulations.J. C. acknowledges support from the European Research Council (ERC) through the Starting Grant No. 714577 PHONOMETA and from the MINECO through a Ramon y Cajal grant (No. RYC-2015-17156). J. S.-D. acknowledges support from the Ministerio de Economia y Competitividad of the Spanish Government and the European Union "Fondo Europeo de Desarrollo Regional (FEDER)" through Project No. TEC2014-53088-C3-1-R. P. S.-J. acknowledges support from MINECO/FEDER under Grant No. FIS2015-65706-P. D. T. acknowledges financial support through the Ramon y Cajal fellowship under Grant No. RYC-2016-21188 and to the Ministry of Science, Innovation and Universities through Project No. RTI2018-093921-A-C42.Gao, P.; Torrent Martí, D.; Cervera Moreno, FS.; San-Jose, P.; Sánchez-Dehesa Moreno-Cid, J.; Christensen, J. (2019). Majorana-like Zero Modes in Kekule Distorted Sonic Lattices. Physical Review Letters. 123(19):196601-1-196601-4. https://doi.org/10.1103/PhysRevLett.123.196601S196601-1196601-412319Hasan, M. Z., & Kane, C. L. (2010). Colloquium: Topological insulators. Reviews of Modern Physics, 82(4), 3045-3067. doi:10.1103/revmodphys.82.3045Elliott, S. R., & Franz, M. (2015). Colloquium: Majorana fermions in nuclear, particle, and solid-state physics. Reviews of Modern Physics, 87(1), 137-163. doi:10.1103/revmodphys.87.137Acín, A., Bloch, I., Buhrman, H., Calarco, T., Eichler, C., Eisert, J., … Wilhelm, F. K. (2018). The quantum technologies roadmap: a European community view. New Journal of Physics, 20(8), 080201. doi:10.1088/1367-2630/aad1eaAlicea, J. (2012). New directions in the pursuit of Majorana fermions in solid state systems. Reports on Progress in Physics, 75(7), 076501. doi:10.1088/0034-4885/75/7/076501Nayak, C., Simon, S. H., Stern, A., Freedman, M., & Das Sarma, S. (2008). Non-Abelian anyons and topological quantum computation. Reviews of Modern Physics, 80(3), 1083-1159. doi:10.1103/revmodphys.80.1083Kushwaha, M. S., Halevi, P., Dobrzynski, L., & Djafari-Rouhani, B. (1993). Acoustic band structure of periodic elastic composites. Physical Review Letters, 71(13), 2022-2025. doi:10.1103/physrevlett.71.2022Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0Yang, Z., Gao, F., Shi, X., Lin, X., Gao, Z., Chong, Y., & Zhang, B. (2015). Topological Acoustics. Physical Review Letters, 114(11). doi:10.1103/physrevlett.114.114301He, C., Ni, X., Ge, H., Sun, X.-C., Chen, Y.-B., Lu, M.-H., … Chen, Y.-F. (2016). Acoustic topological insulator and robust one-way sound transport. Nature Physics, 12(12), 1124-1129. doi:10.1038/nphys3867Lu, J., Qiu, C., Ye, L., Fan, X., Ke, M., Zhang, F., & Liu, Z. (2016). Observation of topological valley transport of sound in sonic crystals. Nature Physics, 13(4), 369-374. doi:10.1038/nphys3999Deng, Y., Ge, H., Tian, Y., Lu, M., & Jing, Y. (2017). Observation of zone folding induced acoustic topological insulators and the role of spin-mixing defects. Physical Review B, 96(18). doi:10.1103/physrevb.96.184305Wang, M., Ye, L., Christensen, J., & Liu, Z. (2018). Valley Physics in Non-Hermitian Artificial Acoustic Boron Nitride. Physical Review Letters, 120(24). doi:10.1103/physrevlett.120.246601Zhang, Z., Tian, Y., Cheng, Y., Wei, Q., Liu, X., & Christensen, J. (2018). Topological Acoustic Delay Line. Physical Review Applied, 9(3). doi:10.1103/physrevapplied.9.034032Zhang, X., Xiao, M., Cheng, Y., Lu, M.-H., & Christensen, J. (2018). Topological sound. Communications Physics, 1(1). doi:10.1038/s42005-018-0094-4Jackiw, R., & Rossi, P. (1981). Zero modes of the vortex-fermion system. Nuclear Physics B, 190(4), 681-691. doi:10.1016/0550-3213(81)90044-4Shore, J. D., Huang, M., Dorsey, A. T., & Sethna, J. P. (1989). Density of states in a vortex core and the zero-bias tunneling peak. Physical Review Letters, 62(26), 3089-3092. doi:10.1103/physrevlett.62.3089Gygi, F., & Schluter, M. (1990). Electronic tunneling into an isolated vortex in a clean type-II superconductor. Physical Review B, 41(1), 822-825. doi:10.1103/physrevb.41.822Torrent, D., & Sánchez-Dehesa, J. (2012). Acoustic Analogue of Graphene: Observation of Dirac Cones in Acoustic Surface Waves. Physical Review Letters, 108(17). doi:10.1103/physrevlett.108.174301Kekuié, A. (1866). Untersuchungen über aromatische Verbindungen Ueber die Constitution der aromatischen Verbindungen. I. Ueber die Constitution der aromatischen Verbindungen. Annalen der Chemie und Pharmacie, 137(2), 129-196. doi:10.1002/jlac.18661370202Read, N., & Green, D. (2000). Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries and the fractional quantum Hall effect. Physical Review B, 61(15), 10267-10297. doi:10.1103/physrevb.61.10267Fu, L., & Kane, C. L. (2008). Superconducting Proximity Effect and Majorana Fermions at the Surface of a Topological Insulator. Physical Review Letters, 100(9). doi:10.1103/physrevlett.100.096407Nishida, Y., Santos, L., & Chamon, C. (2010). Topological superconductors as nonrelativistic limits of Jackiw-Rossi and Jackiw-Rebbi models. Physical Review B, 82(14). doi:10.1103/physrevb.82.144513Hou, C.-Y., Chamon, C., & Mudry, C. (2007). Electron Fractionalization in Two-Dimensional Graphenelike Structures. Physical Review Letters, 98(18). doi:10.1103/physrevlett.98.186809Caroli, C., De Gennes, P. G., & Matricon, J. (1964). Bound Fermion states on a vortex line in a type II superconductor. Physics Letters, 9(4), 307-309. doi:10.1016/0031-9163(64)90375-

Broadband Acoustic Cloaking within an Arbitrary Hard Cavity

This paper reports the design, fabrication, and experimental validation of a broadband acoustic cloak for the concealing of three-dimensional (3D) objects placed inside an open cavity with arbitrary surfaces. This 3D cavity cloak represents the acoustic analogue of a magician hat, giving the illusion that a cavity with an object is empty. Transformation acoustics is employed to design this cavity cloak, whose parameters represent an anisotropic acoustic metamaterial. A practical realization is made of 14 perforated layers fabricated by drilling subwavelength holes on 1-mm-thick Plexiglas plates. In both simulation and experimental results, concealing of the reference object by the device is shown for airborne sound with wavelengths between 10 cm and 17 cm.W. W. K. and V. M. G.-C. contributed equally to this work. W. W. K., B. L., and J. C. C. acknowledge support by the National Basic Research Program of China (973 Program) (Grants No. 2010CB327803 and No. 2012CB921504), National Natural Science Foundation of China (Grants No. 11174138, No. 11174139, No. 11222442, No. 81127901, and No. 11274168), NCET-12-0254, a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions and a program supported by China Scholarship Council (CSC). W. W. K. was also supported by the program for outstanding Ph.D. students of Nanjing University. V. M. G.-C, F. C., and J. S.-D. acknowledge financial support from the U.S. Office of Naval Research under Grant No. N00014-12-1-0216 and from the Spanish Ministerio de Economia y Competitividad under Grant No. TEC2010-19751.Kan, W.; Garcia Chocano, VM.; Cervera Moreno, FS.; Liang, B.; Zou, X.; Yin, L.; Cheng, J.... (2015). Broadband Acoustic Cloaking within an Arbitrary Hard Cavity. Physical Review Applied. 3(6):064019-1-064019-9. doi:10.1103/PhysRevApplied.3.064019S064019-1064019-93

Radial Photonic Crystal for detection of frequency and position of radiation sources

Based on the concepts of artificially microstructured materials, i.e. metamaterials, we present here the first practical realization of a radial wave crystal. This type of device was introduced as a theoretical proposal in the field of acoustics, and can be briefly defined as a structured medium with radial symmetry, where the constitutive parameters are invariant under radial geometrical translations. Our practical demonstration is realized in the electromagnetic microwave spectrum, because of the equivalence between the wave problems in both fields. A device has been designed, fabricated and experimentally characterized. It is able to perform beam shaping of punctual wave sources, and also to sense position and frequency of external radiators. Owing to the flexibility offered by the design concept, other possible applications are discussed.This work was supported in part by the Spanish Ministry of Science and Innovation under Grants TEC 2010-19751 and CSD2008-00066 (Consolider program) and by the U.S. Office of Naval Research under Grant N000140910554.Carbonell Olivares, J.; Díaz Rubio, A.; Torrent Martí, D.; Cervera Moreno, FS.; Kirleis, MA.; Pique, A.; Sánchez-Dehesa Moreno-Cid, J. (2012). Radial Photonic Crystal for detection of frequency and position of radiation sources. Scientific Reports. 2(558):1-8. https://doi.org/10.1038/srep00558S182558Pendry, J., Schurig, D. & Smith, D. Controlling electromagnetic fields. Science 312, 1780–1782 (2006).Leonhardt, U. Optical conformal mapping. Science 312, 1777–1780 (2006).Smith, D., Padilla, W., Vier, D., Nemat-Nasser, S. & Schultz, S. Composite medium with simultaneously negative permeability and permittivity. Phys. Rev. Lett. 84, 4184–4187 (2000).Pendry, J. B. Negative refraction makes a perfect lens. Phys. Rev. Lett. 85, 3966–3969 (2000).Schurig, D. et al. Metamaterial electromagnetic cloak at microwave frequencies. Science 314, 977–980 (2006).Narimanov, E. E. & Kildishev, A. V. Optical black hole: Broadband omnidirectional light absorber. Appl. Phys. Lett. 95, 041106 (2009).Grbic, A. & Eleftheriades, G. Overcoming the diffraction limit with a planar left-handed transmission-line lens. Phys. Rev. Lett. 92, 117403 (2004).Ma, H. F. & Cui, T. J. Three-dimensional broadband ground-plane cloak made of metamaterials. Nature Communications 1, 21 (2010).Engheta, N., Salandrino, A. & Alu, A. Circuit elements at optical frequencies: Nanoinductors, nanocapacitors and nanoresistors. Phys. Rev. Lett. 95, 095504 (2005).Zhang, F. et al. Negative-Zero-Positive Refractive Index in a Prism-Like Omega-Type Metamaterial. IEEE Trans. Microwave Theory Tech. 56, 2566–2573 (2008).Baena, J., Marques, R., Medina, F. & Martel, J. Artificial magnetic metamaterial design by using spiral resonators. Phys. Rev. B 69, 014402 (2004).Carbonell, J., Torrent, D., Diaz-Rubio, A. & Sanchez-Dehesa, J. Multidisciplinary approach to cylindrical anisotropic metamaterials. New J. Phys. 13, 103034 (2011).Torrent, D. & Sanchez-Dehesa, J. Radial Wave Crystals: Radially Periodic Structures from Anisotropic Metamaterials for Engineering Acoustic or Electromagnetic Waves. Phys. Rev. Lett. 103, 064301 (2009).Torrent, D. & Sanchez-Dehesa, J. Acoustic resonances in two-dimensional radial sonic crystal shells. New J. Phys. 12, 073034 (2010).Kurs, A. et al. Wireless power transfer via strongly coupled magnetic resonances. Science 317, 83–86 (2007).Marques, R., Medina, F. & Rafii-El-Idrissi, R. Role of bianisotropy in negative permeability and left-handed metamaterials. Phys. Rev. B 65, 144440 (2002).Pendry, J. B., Holden, A. J., Robbins, D. J. & Stewart, W. J. Magnetism from conductors and enhanced nonlinear phenomena. IEEE Trans. Microwave Theory Tech. 47, 2075–2084 (1999).Pollock, J. G. & Iyer, A. K. Effective-Medium Properties of Cylindrical Transmission-Line Metamaterials. IEEE Antennas and Wireless Propagation Letters 10, 1491–1494 (2011).Comsol, A. B. (Sweden). Comsol Multiphysics (v. 4.1). (2010).Ansoft. High Frequency Structure Simulator (HFSS), v.14. (2012).Smith, D. R., Vier, D. C., Koschny, T. & Soukoulis, C. M. Electromagnetic parameter retrieval from inhomogeneous metamaterials. Phys. Rev. E 71, 036617 (2005).Yang, Y. et al. Optofluidic waveguide as a transformation optics device for lightwave bending and manipulation. Nature Communications 3, 651 (2012).Liu, R. et al. Broadband Ground-Plane Cloak. Science 323, 366–369 (2009).Cheng, Q., Cui, T. J., Jiang, W. X. & Cai, B. G. An omnidirectional electromagnetic absorber made of metamaterials. New J. Phys. 12, 063006 (2010)

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Acoustic cloack for airborne sound by inverse design

[EN] This Letter presents practical realization of a two-dimensional low loss acoustic cloak for airborne sound obtained by inverse design. The cloak consists of 120 aluminum cylinders of 15 mm diameter surrounding the cloaked object¿a cylinder of diameter 22.5 cm. The position of each cylinder in the cloak is optimized using the data from two different techniques: genetic algorithm and simulated annealing. The operation frequency of this cloak is 3061 Hz with the bandwidth of about 100 Hz. Being a multi-step approach to the desired cloaking, the inverse design is also valid, in principle, for non-symmetric cylinders and even for three-dimensional objects. VC 2011 American Institute of PhysicsWork supported by ONR under Award N000140910554 and the Spanish MCINN under Contract Nos. TEC2010-19751, TEC2008-06756-C03-03, and CSD2008-00066 (CONSOLIDER Program). L. S. thanks the fellowship provided by CSIC with number JAEDoc-08-00351.García Chocano, VM.; Sanchis, L.; Díaz Rubio, A.; Martínez Pastor, JP.; Cervera Moreno, FS.; Llopis Pontiveros, R.; Sánchez-Dehesa Moreno-Cid, J. (2011). Acoustic cloack for airborne sound by inverse design. Applied Physics Letters. 99(7):74102-74102. https://doi.org/10.1063/1.3623761S741027410299

Nonlocal electrodinamics of homogenized metal-dielectric photonic crystals

[EN] The nonlocal effective permittivity tensor for photonic crystals (PCs), having dielectric and metallic inclusions in the unit cell, is calculated and analyzed within the homogenization theory based on the Fourier formalism and the form-factor division approach. A method allowing us to extract the effective bianisotropic metamaterial parameters (permeability and chirality) from the wave vector dependence of the nonlocal effective dielectric response is proposed. Both the original nonlocal dielectric response parameters and the new bianisotropic metamaterial ones reproduce the photonic band structure of the artificial crystal far beyond the long wavelength limit and for a wide class of metal-dielectric structures. To calculate the optical spectra (reflection and transmission) of finite-size PC, the nonlocal homogenization approach is extended with the method of expansion into photonic bulk-modes (Bloch waves). The application of the developed theory is illustrated with well-known forms of metallic inclusions (slabs, thin wires, split-ring resonators) and experimentally confirmed with novel designs based on metallic crosses.This work was partially supported by Red-PRODEP, PRO-FOCIE, CONACYT (Grant No. CB-2011-01-166382), and VIEP-BUAP. Experimental measurements were carried out with support of Wave Phenomena Group of Universitat Politecnica de Valencia and Photonics Group of University of California San Diego. F C and J S-D acknowledge the financial support by the Ministerio de Economia y Competitividad of the Spanish government and the European Union Fondo Europeo de Desarrollo Regional (FEDER) (Grant No. TEC2014-53088-C3-1-R).Konovalenko, A.; Reyes-Avendaño, JA.; Méndez-Blas, A.; Cervera Moreno, FS.; Myslivets, E.; Radic, S.; Sánchez-Dehesa Moreno-Cid, J.... (2019). Nonlocal electrodinamics of homogenized metal-dielectric photonic crystals. Journal of Optics. 21(8):1-16. https://doi.org/10.1088/2040-8986/ab2a4eS11621

Three-dimensional axisymmetric cloak based on the cancellation of acoustic scattering from a sphere

This Letter presents the design, fabrication, and experimental characterization of a directional threedimensional acoustic cloak for airborne sound. The cloak consists of 60 concentric acoustically rigid tori surrounding the cloaked object, a sphere of radius 4 cm. The major radii and positions of the tori along the symmetry axis are determined using the condition of complete cancellation of the acoustic field scattered from the sphere. They are obtained through an optimization technique that combines genetic algorithm and simulated annealing. The scattering cross section of the sphere with the cloak, which is the magnitude that is minimized, is calculated using the method of fundamental solutions. The low-loss fabricated cloak shows a reduction of the 90% of the sphere scattering cross section at the frequency of 8.55 kHz.This work is partially supported by the Spanish Ministerio de Economia y Competitividad under Contracts No. TEC2010-19751, No. TEC2011-29120-C05-01, and No. CSD2008-00066 (CONSOLIDER Program), and by the U.S. Office of Naval Research. The authors acknowledge the "Centro de Tecnologias Fisicas'' at the UPV for technical help during data acquisition. We also acknowledge the computing facilities provided by the Universidad de Valencia.Sanchis Martínez, L.; García Chocano, VM.; Llopis Pontiveros, R.; Climente Alarcón, A.; Martínez Pastor, J.; Cervera Moreno, FS.; Sánchez-Dehesa Moreno-Cid, J. (2013). Three-dimensional axisymmetric cloak based on the cancellation of acoustic scattering from a sphere. Physical Review Letters. 110(12). https://doi.org/10.1103/PhysRevLett.110.124301S11012Milton, G. W., Briane, M., & Willis, J. R. (2006). On cloaking for elasticity and physical equations with a transformation invariant form. New Journal of Physics, 8(10), 248-248. doi:10.1088/1367-2630/8/10/248Cummer, S. A., & Schurig, D. (2007). One path to acoustic cloaking. New Journal of Physics, 9(3), 45-45. doi:10.1088/1367-2630/9/3/045Norris, A. N. (2009). Acoustic metafluids. The Journal of the Acoustical Society of America, 125(2), 839-849. doi:10.1121/1.3050288Chen, H., & Chan, C. T. (2007). Acoustic cloaking in three dimensions using acoustic metamaterials. Applied Physics Letters, 91(18), 183518. doi:10.1063/1.2803315Cummer, S. A., Popa, B.-I., Schurig, D., Smith, D. R., Pendry, J., Rahm, M., & Starr, A. (2008). Scattering Theory Derivation of a 3D Acoustic Cloaking Shell. Physical Review Letters, 100(2). doi:10.1103/physrevlett.100.024301Guild, M. D., Alù, A., & Haberman, M. R. (2011). Cancellation of acoustic scattering from an elastic sphere. The Journal of the Acoustical Society of America, 129(3), 1355-1365. doi:10.1121/1.3552876Martin, T. P., & Orris, G. J. (2012). Hybrid inertial method for broadband scattering reduction. Applied Physics Letters, 100(3), 033506. doi:10.1063/1.3678633Torrent, D., & Sánchez-Dehesa, J. (2008). Acoustic cloaking in two dimensions: a feasible approach. New Journal of Physics, 10(6), 063015. doi:10.1088/1367-2630/10/6/063015Cheng, Y., Yang, F., Xu, J. Y., & Liu, X. J. (2008). A multilayer structured acoustic cloak with homogeneous isotropic materials. Applied Physics Letters, 92(15), 151913. doi:10.1063/1.2903500Zhang, S., Xia, C., & Fang, N. (2011). Broadband Acoustic Cloak for Ultrasound Waves. Physical Review Letters, 106(2). doi:10.1103/physrevlett.106.024301Popa, B.-I., Zigoneanu, L., & Cummer, S. A. (2011). Experimental Acoustic Ground Cloak in Air. Physical Review Letters, 106(25). doi:10.1103/physrevlett.106.253901Farhat, M., Guenneau, S., & Enoch, S. (2009). 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