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The properties of sonic crystals (SC) are theoretically investigated in this work by solving the inverse problem k(¿) using the extended plane wave expansion (EPWE). The solution of the resulting eigenvalue problem gives the complex band structure which takes into account both the propagating and the evanescent modes. In this work we show the complete mathematical formulation of the EPWE for SC and the supercell approximation for its use in both a complete SC and a SC with defects. As an example we show a novel interpretation of the deaf bands in a complete SC in good agreement with multiple scattering simulations. © 2011 Copyright 2011 Author(s). ; This work was supported by MCI-Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under grant MAT2009-09438. LMGR would like to thank the UPV for the grant PAID-00-11. VRG is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)." ; Romero García, V.; García Raffi, LM.; Sánchez Pérez, JV. (2011). Evanescent waves and deaf bands in sonic crystals. AIP Advances. 1(4):416011-416019. https://doi.org/10.1063/1.3675801 ; S ; 416011 ; 416019 ; 1 ; 4

[EN] The effect of the presence of a finite impedance surface on the wave propagation properties of a two-dimensional periodic array of rigid cylinders with their axes perpendicular to the surface is both numerically and experimentally analyzed in this work. In this realistic situation the incident wave interacts with two elements: the surface and the array of scatterers. The excess attenuation and the bandgap effects, due to the existence of the surface and the periodicity of the array, respectively, are fundamental to control both the transmission and attenuation of waves on devices based on periodicity. © 2011 Europhysics Letters Association. ; This work was supported by MCI Secretaria de Estado de Investigacion (Spanish Government) and FEDER funds, under grant MAT2009-09438. VR-G is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)". ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2011). Analysis of the wave propagation properties of a periodic array of rigid cylinders perpendicular to a finite impedance surface. EPL. 96:440031-440036. https://doi.org/10.1209/0295-5075/96/44003 ; S ; 440031 ; 440036 ; 96

The use of sonic crystals (SCs) as environmental noise barriers has certain advantages from both the acoustical and the constructive points of view with regard to conventional ones. However, the interaction between the SCs and the ground has not been studied yet. In this work we are reporting a semi-analytical model, based on the multiple scattering theory and on the method of images, to study this interaction considering the ground as a finite impedance surface. The results obtained here show that this model could be used to design more effective noise barriers based on SCs because the excess attenuation of the ground could be modelled in order to improve the attenuation properties of the array of scatterers. The results are compared with experimental data and numerical predictions thus finding good agreement between them. © 2011 IOP Publishing Ltd. ; The authors would like to thank The Open University (UK) for the use of their facilities. This work was supported by the MEC (Spanish Government) and FEDER funds, under Grant No MAT2009-09438. ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2011). Analytical model to predict the effect of a finite impedance surface on the propagation properties of 2D Sonic Crystals. Journal of Physics D: Applied Physics. 44:1-12. https://doi.org/10.1088/0022-3727/44/26/265501 ; S ; 1 ; 12 ; 44 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Sanchez-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:10.1063/1.1533112 ; Sánchez-Dehesa, J., Garcia-Chocano, V. M., Torrent, D., Cervera, F., Cabrera, S., & Simon, F. (2011). Noise control by sonic crystal barriers made of recycled materials. The Journal of the Acoustical Society of America, 129(3), 1173-1183. doi:10.1121/1.3531815 ; Krynkin, A., ...

Evanescent modes in complete sonic crystals (SCs) and SC with point defects are reported both theoretically and experimentally in this paper. Plane wave expansion (PWE) and in general, ω(k)ω(k) methods have been used to calculate band structures showing gaps that have been interpreted as ranges of frequencies where no real kk exists. In this work, we extend PWE to solve the complex k(ω)k(ω) problem applied to SC, introducing the supercell approximation for studying one vacancy. Explicit matrix formulation of the equations is given. This k(ω)k(ω) method enables the calculation of complex band structures, as well as enabling an analysis of the propagating modes related with real values of the function k(ω)k(ω), and the evanescent modes related with imaginary values of k(ω)k(ω). This paper shows theoretical results and experimental evidences of the evanescent behavior of modes inside the SC band gap. Experimental data and numerical results using the finite elements method are in very good agreement with the predictions obtained using the k(ω)k(ω) method. ; The authors would like to thank Dr. E. A. Sanchez-Perez for his comments and suggestions and thank Daniel Fenollosa and Talleres Ferriols for their help in building the mechanical part of 3DReAMS. This work was supported by MEC (Spanish government) and the European Regional Development Fund, under Grant Nos. MAT2009-09438 and MTM2009-14483-C02-02. ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (2010). Evanescent modes in sonic crystals: complex dispersion relation and supercell approximation. Journal of Applied Physics. 108(4):449071-4490716. doi:10.1063/1.3466988 ; S ; 449071 ; 4490716 ; 108 ; 4 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Kushwaha, M. S., Halevi, P., Dobrzynski, L., & Djafari-Rouhani, B. (1993). Acoustic band structure of periodic elastic composites. Physical Review Letters, 71(13), ...

2123021 2123024 84 ; S ; This work theoretically and experimentally reports the evanescent connections between propagating bands in periodic acoustic materials. The complex band structures obtained by solving for the k(¿) problem reveal a complete interpretation of the propagation properties of these systems. The prediction of evanescent modes, nonpredicted by classical ¿(k - ) methods, is of interest for the understanding of these propagation properties. Complex band structures provide an interpretation of the evanescent coupling and the level repulsion states showing the possibility of controlling evanescent waves in periodic materials. © 2011 American Physical Society. V.R.G. and L.M.G.R. would like to thank the facilities provided by the IEMN UMR CNRS 8520. L.M.G.R. would like to thank the UPV for Grant No. PAID-00-11. V.R.G. is grateful for the support contracts of the UPV CEI-01-11. This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant No. MAT2009-09438. Romero García, V.; Vasseur, J.; Hladky Hennion, AC.; García Raffi, LM.; Sánchez Pérez, JV. (2011). Level repulsion and evanescent waves in sonic crystals. Physical Review B. 84:2123021-2123024. https://doi.org/10.1103/PhysRevB.84.212302

This work theoretically and experimentally reports the evanescent connections between propagating bands in periodic acoustic materials. The complex band structures obtained by solving for the k(¿) problem reveal a complete interpretation of the propagation properties of these systems. The prediction of evanescent modes, nonpredicted by classical ¿(k - ) methods, is of interest for the understanding of these propagation properties. Complex band structures provide an interpretation of the evanescent coupling and the level repulsion states showing the possibility of controlling evanescent waves in periodic materials. © 2011 American Physical Society. ; V.R.G. and L.M.G.R. would like to thank the facilities provided by the IEMN UMR CNRS 8520. L.M.G.R. would like to thank the UPV for Grant No. PAID-00-11. V.R.G. is grateful for the support contracts of the UPV CEI-01-11. This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant No. MAT2009-09438. ; Romero García, V.; Vasseur, J.; Hladky Hennion, AC.; García Raffi, LM.; Sánchez Pérez, JV. (2011). Level repulsion and evanescent waves in sonic crystals. Physical Review B. 84:2123021-2123024. https://doi.org/10.1103/PhysRevB.84.212302 ; S ; 2123021 ; 2123024 ; 84

In this work we present the design and the manufacturing processes, as well as the acoustics standard-ization tests, of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic Crystals. The multiple scattering of waves inside these structures leads to attenuation bands related to the periodicity of the structure by means of Bragg scattering. In order to design the acoustic barrier, two strategies have been used: First, the arrangement of scatterers is based on fractal geometries to maximize the Bragg scattering; econd, multi-phenomena scatterers with several noise con- trol mechanisms, as resonances or absorption, are designed and used to construct the periodic array. The acoustic barrier reported in this work provides a high technological solution in the field of noise control. ; This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant No. MAT2009-09438 and by Universitat Politecnica de Valencia (Programa INNOVA 2010) under grant "INNOVA 2010 PDC PANTALLA ACUSTICA". The authors would like to thank Applus+ (LGAI Technological Center S.A.) for their help. V.R.G. is grateful for the support of post-doctoral contracts of the UPV (CEI-01-11). ; Castiñeira Ibáñez, S.; Rubio Michavila, C.; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM. (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. https://doi.org/10.2478/v10168-012-0057-9 ; S ; 455 ; 462 ; 37 ; 4

An exhaustive study has been made into the potential improvement in attenuation and focusing of phononic crystal arrays resulting from the deliberate creation of vacancies. Use is made of a stochastic search algorithm based on evolutionary algorithms called the epsilon variable multi-objective genetic algorithm which, in conjunction with the application of multiple scattering theory, enables the design of devices for effectively controlling sound waves. Several parameters are analyzed, including the symmetries used in the distribution of holes and the optimum number of holes. The validity and utility of the general rules obtained have been confirmed experimentally. ; This work was partially supported by MEC (Spanish Government) and FEDER funds: Project Nos. 419DPI2005-07835, and MAT2006-03097 and Generalitat Valenciana Project Nos. GV06/026 and 420 GV/2007/191. The authors would like to thank John Rawlins (associate member of the Institute of Translation and Interpreting (No. 9743) of UK, and "Certified PRO" of ProZ according to the EN 15038) for his help with the use of English. ; Romero García, V.; Sánchez Pérez, JV.; García Raffi, LM.; Herrero Durá, JM.; García Nieto, S.; Blasco, X. (2009). Hole distribution in phononic crystals: design and optimization. Journal of the Acoustical Society of America. 125(6):3774-3783. https://doi.org/10.1121/1.3126948 ; S ; 3774 ; 3783 ; 125 ; 6

[EN] It is well known that Genetic Algorithms (GA) is an optimization method which can be used in problems where the traditional optimization techniques are difficult to be applied. Sonic Crystals (SC) are periodic structures that present ranges of sound frequencies related with the periodicity of the structure, where the sound propagation is forbidden. This means that in the acoustic spectrum there are ranges of frequencies with high acoustic attenuation. This attenuation can be improved producing vacancies in the structure. In this paper we use a parallel implementation of a GA to optimize those structures, by means of the creation of vacancies in a starting SC, in order to obtain the best acoustic attenuation in a predetermined range of frequencies. The cost function used in GA is based on the Multiple Scattering Theory (MST), which is a self consistent method for calculating acoustic pressure in SCs. As a final result we achieve a quasi ordered structures that presents a high acoustic attenuation in a predetermined range of frequencies, independent of the periodicity of the SC. ; The authors acknowledge financial support provided by the Spanish MEC (Project No. MAT2006-03097) and by the Generalitat Valenciana (Spain) under Grant No. GV/2007/191. This work also has been partially supported by MEC (Spanish government) and FEDER funds: projects DPI2005-07835, DPI2004- 8383-C03-02 and GVA-026. ; Romero García, V.; Fuster García, E.; Sánchez Pérez, JV.; García Raffi, LM.; Blasco, X.; Herrero Durá, JM.; Sanchís Saez, J. (2007). Genetic Algorithm in the Optimization of the Acoustic Attenuation System. Lecture Notes in Computer Science. 4507:614-621. https://doi.org/10.1007/978-3-540-73007-1_74 ; S ; 614 ; 621 ; 4507 ; Martínez-Sala, R., Sancho, J., Sánchez Pérez, J.V., Llinares, J., Meseguer, F.: Sound attenuation by sculpture. Nature (London) 387, 241 (1995) ; Hushwaha, M.S., Halevi, P., Martínez, G., Dobrynski, L., Djafari-Rouhani, B.: Theory of acoustic band structure of periodic elastic composites. Phys. Rev. B ...