Limits of flexural wave absorption by open lossy resonators: reflection and transmission problems

The limits of flexural wave absorption by open lossy resonators are analytically and numerically reported in this work for both the reflection and transmission problems. An experimental validation for the reflection problem is presented. The reflection and transmission of flexural waves in 1D resonant thin beams are analyzed by means of the transfer matrix method. The hypotheses, on which the analytical model relies, are validated by experimental results. The open lossy resonator, consisting of a finite length beam thinner than the main beam, presents both energy leakage due to the aperture of the resonators to the main beam and inherent losses due to the viscoelastic damping. Wave absorption is found to be limited by the balance between the energy leakage and the inherent losses of the open lossy resonator. The perfect compensation of these two elements is known as the critical coupling condition and can be easily tuned by the geometry of the resonator. On the one hand, the scattering in the reflection problem is represented by the reflection coefficient. A single symmetry of the resonance is used to obtain the critical coupling condition. Therefore the perfect absorption can be obtained in this case. On the other hand, the transmission problem is represented by two eigenvalues of the scattering matrix, representing the symmetric and anti-symmetric parts of the full scattering problem. In the geometry analyzed in this work, only one kind of symmetry can be critically coupled, and therefore, the maximal absorption in the transmission problem is limited to 0.5. The results shown in this work pave the way to the design of resonators for efficient flexural wave absorption

Numerical simulation of subwoofer arraycon gurations using the Finite ElementMethod

[EN] Teaching in the Master of Acoustic Engineering includes contents that require the modeling of acousticsystems of two types: simple systems through analytical theory and complex models using simulationtechniques. In the present work, we describe an example of complex acoustic sources modeling using the nite element method: subwoofer sound radiation in di erent con gurations. Numerical simulations inthe frequency domain can calculate the radiation pattern of systems that do not have a simple analyticalsolution[ES] La enseñanza en el Máster de Ingeniería Acústica incluye contenido que requiere la modelización de sistemas acústicos de dos tipos: sistemas simples usando la teoría analítica y modelos complejos usando técnicas de simulación. En este trabajo, se describe un ejemplo de modelado de fuentes acústicas complejas mediante el método de los elementos finitos: la radiación sonora del altavoz de subgraves en diferentes configuraciones. Las simulaciones numéricas en el dominio de la frecuencia permiten calcular el patrón de radiación de sistemas que no tienen una solución analítica sencilla.Banyuls-Juan, X.; Atiénzar-Navarro, R.; Picó, R. (2017). Simulación numérica de un conjunto de altavoces subwofers utilizando Elementos Finitos. Modelling in Science Education and Learning. 10(2):203-210. doi:10.4995/msel.2017.7653SWORD203210102Olson, H. (1957). Acoustical Engineering, Second Edition. D. Van Nostrand Company, Princeton, New Jersey.Courant, R., Friedrichs, K., & Lewy, H. (1967). On the Partial Difference Equations of Mathematical Physics. IBM Journal of Research and Development, 11(2), 215-234. doi:10.1147/rd.112.0215La Roda J. (2009). Ajuste de conguraciones cardioides de subgraves. DAS Audio, Departamento de Ingeniería

Nonlinear waves in a chain of magnetically coupled pendula

A motivation for the study of reduced models like one-dimensional systems in Solid State Physics is the complexity of the full problem. In recent years our group has studied theoretically, numerically and experimentally wave propagation in lattices of nonlinearly coupled oscillators. Here, we present the dynamics of magnetically coupled pendula lattices. These macroscopic systems can model the dynamical processes of matter or layered systems. We report the results obtained for harmonic wave propagation in these media, and the different regimes of mode conversion into higher harmonics strongly influenced by dispersion and discreteness, including the phenomenon of acoustic dilatation of the chain, as well as some results on the propagation of localized waves i.e., solitons and kinks.Generalitat Valenciana APOSTD/2017/042Umiversitat Politècnica de València PAID-01-14Ministerio de Economía y Competitividad (MINECO), Spain FIS2015-65998-C2-2-PJunta de Andalucía 2017/FQM-28

Modelling of continuous elastic systems byusing the Finite Element Method

[EN] Propagation of mechanical waves in unidimensional systems is a fundamental part of physics, necessaryfor learning subjects such as acoustics and vibrations. The vibration of transverse waves in strings isthe easiest case of elastic system. Usually, this is the rst continuous elastic system in which studentsapply fundamental mathematical concepts as vibration mode, equation of motion and boundary condition.In this work the use of simulation methods is proposed to reinforce the understanding of vibratory andacoustic simple phenomena. This will be applied to the case of a string, a beam and a membrane of nitelength with di erent physical characteristics and boundary condition[ES] La propagación de ondas mecánicas en sistemas unidimensionales es una parte fundamental de la física, necesaria para el aprendizaje de asignaturas como acústica y vibraciones. La vibración de ondas transversales en cuerdas es el caso más sencillo de sistema elástico. Habitualmente, este es el primer sistema elástico continuo en el cual los alumnos aplican conceptos matemáticos fundamentales como modo de vibración, ecuación de movimiento y condición de contorno. En este trabajo se propone el uso de los métodos de simulación para reforzar la comprensión de fenómenos simples en acústica y vibraciones. Lo aplicaremos a los casos de cuerda vibrante, barras y membranas de longitud finita con diferentes características físicas y condiciones de contornoHerrero-Durá, I.; Picó, R.; Sánchez-Morcillo, V.; Garcia-Raffi, L. (2017). Modelización de sistemas elásticos continuos mediante el Método de Elementos Finitos. Modelling in Science Education and Learning. 10(2):193-202. doi:10.4995/msel.2017.7659SWORD193202102Giere, R. N. (1988). Explaining Science. doi:10.7208/chicago/9780226292038.001.0001Gilbert, S. W. (1991). Model building and a definition of science. Journal of Research in Science Teaching, 28(1), 73-79. doi:10.1002/tea.3660280107Tomasi, J. (1988). Models and modeling in theoretical chemistry. Journal of Molecular Structure: THEOCHEM, 179(1), 273-292. doi:10.1016/0166-1280(88)80128-3Gobert, J. D., & Buckley, B. C. (2000). Introduction to model-based teaching and learning in science education. International Journal of Science Education, 22(9), 891-894. doi:10.1080/095006900416839Gilbert, J. K. (2004). Models and Modelling: Routes to More Authentic Science Education. International Journal of Science and Mathematics Education, 2(2), 115-130. doi:10.1007/s10763-004-3186-4Kinzl, M., Schwiedrzik, J., Zysset, P. K., & Pahr, D. H. (2013). An experimentally validated finite element method for augmented vertebral bodies. Clinical Biomechanics, 28(1), 15-22. doi:10.1016/j.clinbiomech.2012.09.008Kabir, K. M. M., Matthews, G. I., Sabri, Y. M., Russo, S. P., Ippolito, S. J., & Bhargava, S. K. (2016). Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device. Smart Materials and Structures, 25(3), 035040. doi:10.1088/0964-1726/25/3/035040Yu, C.-C., Chu, J. P., Jia, H., Shen, Y.-L., Gao, Y., Liaw, P. K., & Yokoyama, Y. (2017). Influence of thin-film metallic glass coating on fatigue behavior of bulk metallic glass: Experiments and finite element modeling. Materials Science and Engineering: A, 692, 146-155. doi:10.1016/j.msea.2017.03.071Oladejo K.A., Abu R. and Adewale M.D. (2012). Effective Modeling and Simulation of Engineering Problems with COMSOL Multiphysics. International Journal of Science and Technology 2(10), 742-748.Kinsler L.E., Frey A.R., Coppens A.B. and Sanders J.V. (2000). Fundamentals of Acoustics (4th ed.). United States of America: John Wiley & Sons, Inc

Resistance to melon vine decline derived from Cucumis melo spp. agrestis: genetic analysis of root structure and root response.

Melon vine decline is a major soilborne disease that causes severe economic losses around the world

Habilidades del psicólogo en drogodependencias

Las habilidades del terapeuta constituyen un aspecto fundamental para la consecución de los distintos objetivos que al psicólogo se le plantean en el transcurso de su intervención con el usuario drogodependiente. En este articulo se presenta una revisión de las habilidades que los autores consideran imprescindibles, aportando ejemplos prácticos y con independencia de la orientación teórica del psicólogo. Las habilidades técnicas o profesionales se refieren a conocimientos teóricos y prácticos; el afltocontrol emocional, incluyendo tanto el afrontamiento ef caz por parte del psicólogo de ciertas situaciones ante el usuario, y especificamente si éste es un drogodelincuente, como el afrontamiento del burn out; y por último, las habilidades sociales, en las que se sustenta la interacción entre el psicólogo y el usuario, destacando la asertividad y la empatia. Finalmente se revisan distintos aspectos y principios generales referidos a la ética profesional en la práctica de la Psicologia Clínica

Evidences of spatial (angular) filtering of sound beams by sonic crystals

We report experimental evidences of spatial (angular) filtering of sound beams propagating through sonic crystals. We show that at specific frequencies of the incident wave the paraxial plane wave compo- nents of the beam can be efficiently transmitted through the crystal, whereas the components propagat- ing at large angles are strongly reflected or deflected (filtered out) by the crystal. The modification of the angular field distribution results in formation of sound beams of relatively high spatial quality.The work was financieall supported by Spanish Ministry of since and Innovation and European Union FEDER through projects FIS2011-29731-C02-01 and -02, Generalitat Valenciana through the procect GV/2011/2055 and the UPV through PAID-05-12.Picó Vila, R.; Pérez Arjona, I.; Sánchez Morcillo, VJ.; Staliünas, K. (2013). Evidences of spatial (angular) filtering of sound beams by sonic crystals. Applied Acoustics. 74(7):945-948. https://doi.org/10.1016/j.apacoust.2013.01.003S94594874

Large-scale gene gains and losses molded the NLR defense arsenal during the Cucurbita evolution

[EN] Main conclusion Genome-wide annotation reveals that the gene birth-death process of the Cucurbita R family is associated with a species-specific diversification of TNL and CNL protein classes. The Cucurbitaceae family includes nearly 1000 plant species known universally as cucurbits. Cucurbita genus includes many economically important worldwide crops vulnerable to more than 200 pathogens. Therefore, the identification of pathogen-recognition genes is of utmost importance for this genus. The major class of plant-resistance (R) genes encodes nucleotide-binding site and leucine-rich repeat (NLR) proteins, and is divided into three sub-classes namely, TIR-NB-LRR (TNL), CC-NB-LRR (CNL) and RPW8-NB-LRR (RNL). Although the characterization of the NLR gene family has been carried out in important Cucurbita species, this information is still linked to the availability of sequenced genomes. In this study, we analyzed 40 de novo transcriptomes and 5 genome assemblies, which were explored to investigate the Cucurbita expressed-NLR (eNLR) and NLR repertoires using an ad hoc gene annotation approach. Over 1850 NLR-encoding genes were identified, finely characterized and compared to 96 well-characterized plant R-genes. The maximum likelihood analyses revealed an unusual diversification of CNL/TNL genes and a strong RNL conservation. Indeed, several gene gain and loss events have shaped the Cucurbita NLR family. Finally, to provide a first validation step Cucurbita, eNLRs were explored by real-time PCR analysis. The NLR repertories of the 12 Cucurbita species presented in this paper will be useful to discover novel R-genes.Open access funding provided by Universita degli Studi di Napoli Federico II within the CRUI-CARE Agreement.Andolfo, G.; Sáez-Sánchez, C.; Cañizares Sales, J.; Picó Sirvent, MB.; Ercolano, MR. (2021). Large-scale gene gains and losses molded the NLR defense arsenal during the Cucurbita evolution. Planta. 254(4):1-14. https://doi.org/10.1007/s00425-021-03717-xS114254

Simulation of gauge transformations on systems of ultracold atoms

We show that gauge transformations can be simulated on systems of ultracold atoms. We discuss observables that are invariant under these gauge transformations and compute them using a tensor network ansatz that escapes the phase problem. We determine that the Mott-insulator-to-superfluid critical point is monotonically shifted as the induced magnetic flux increases. This result is stable against the inclusion of a small amount of entanglement in the variational ansatz.Comment: 14 pages, 6 figure

Formation of high-order acoustic Bessel beams by spiral diffraction gratings

The formation of high-order Bessel beams by a passive acoustic device consisting of an Archimedes' spiral diffraction grating is theoretically, numerically, and experimentally reported in this paper. These beams are propagation-invariant solutions of the Helmholtz equation and are characterized by an azimuthal variation of the phase along its annular spectrum producing an acoustic vortex in the near field. In our system, the scattering of plane acoustic waves by the spiral grating leads to the formation of the acoustic vortex with zero pressure on axis and the angular phase dislocations characterized by the spiral geometry. The order of the generated Bessel beam and, as a consequence, the size of the generated vortex can be fixed by the number of arms in the spiral diffraction grating. The obtained results allow for obtaining Bessel beams with controllable vorticity by a passive device, which has potential applications in low-cost acoustic tweezers and acoustic radiation force devices.We acknowledge financial support from MINECO of the Spanish Government under Grants No. MTM2012-36740-C02-02, No. FIS2015-65998-C2-1-P, and No. FIS2015-65998-C2-2-P. N.J. acknowledges financial support from PAID-2011 Universitat Politecnica de Valencia.Jimenez, N.; Picó Vila, R.; Sánchez Morcillo, VJ.; Romero García, V.; García-Raffi, LM.; Staliünas, K. (2016). Formation of high-order acoustic Bessel beams by spiral diffraction gratings. Physical Review E. 94(5). doi:10.1103/PhysRevE.94.053004S05300494