Characterization of Sheep Wool as a Sustainable Material for Acoustic Applications

[EN] In recent years, natural materials are becoming a valid alternative to traditional sound absorbers due to reduced production costs and environmental protection. This paper reports the acoustical characterization of sheep wool. Measurements on normal incidence and diffuse-incidence sound absorption coefficients of different samples are reported. The airflow resistance has also been measured. The results prove that sheep wool has a comparable sound absorption performance to that of mineral wool or recycled polyurethane foam. An empirical model is used to calculate the sound absorption of sheep wool samples. A reasonable agreement on the acoustic absorption of all sheep wool samples is obtained.This work was financially supported by the project BIA2013-41537-R (BIAEFIREMAT "Development of new eco-materials and sustainable constructive solutions based on the use of waste and renewable raw materials"), funded by the Ministry of Economy and Competitiveness of Spain and co-financed with ERDF funds, within the National RDI Programme focused on the Challenges of Society 2013Rey Tormos, RMD.; Uris Martínez, A.; Alba, J.; Candelas Valiente, P. (2017). Characterization of Sheep Wool as a Sustainable Material for Acoustic Applications. Materials. 10(11):1-11. https://doi.org/10.3390/ma10111277S1111011Pinto, J., Cruz, D., Paiva, A., Pereira, S., Tavares, P., Fernandes, L., & Varum, H. (2012). Characterization of corn cob as a possible raw building material. Construction and Building Materials, 34, 28-33. doi:10.1016/j.conbuildmat.2012.02.014Briga-Sá, A., Nascimento, D., Teixeira, N., Pinto, J., Caldeira, F., Varum, H., & Paiva, A. (2013). Textile waste as an alternative thermal insulation building material solution. Construction and Building Materials, 38, 155-160. doi:10.1016/j.conbuildmat.2012.08.037Binici, H., Eken, M., Dolaz, M., Aksogan, O., & Kara, M. (2014). An environmentally friendly thermal insulation material from sunflower stalk, textile waste and stubble fibres. Construction and Building Materials, 51, 24-33. doi:10.1016/j.conbuildmat.2013.10.038Korjenic, A., Klarić, S., Hadžić, A., & Korjenic, S. (2015). Sheep Wool as a Construction Material for Energy Efficiency Improvement. Energies, 8(6), 5765-5781. doi:10.3390/en8065765Lopez Hurtado, P., Rouilly, A., Vandenbossche, V., & Raynaud, C. (2016). A review on the properties of cellulose fibre insulation. Building and Environment, 96, 170-177. doi:10.1016/j.buildenv.2015.09.031Lopez Hurtado, P., Rouilly, A., Raynaud, C., & Vandenbossche, V. (2016). The properties of cellulose insulation applied via the wet spray process. Building and Environment, 107, 43-51. doi:10.1016/j.buildenv.2016.07.017Binici, H., Aksogan, O., & Demirhan, C. (2016). Mechanical, thermal and acoustical characterizations of an insulation composite made of bio-based materials. Sustainable Cities and Society, 20, 17-26. doi:10.1016/j.scs.2015.09.004Asdrubali, F., Bianchi, F., Cotana, F., D’Alessandro, F., Pertosa, M., Pisello, A. L., & Schiavoni, S. (2016). Experimental thermo-acoustic characterization of innovative common reed bio-based panels for building envelope. Building and Environment, 102, 217-229. doi:10.1016/j.buildenv.2016.03.022Ballagh, K. O. (1996). Acoustical properties of wool. Applied Acoustics, 48(2), 101-120. doi:10.1016/0003-682x(95)00042-8Ersoy, S., & Küçük, H. (2009). Investigation of industrial tea-leaf-fibre waste material for its sound absorption properties. Applied Acoustics, 70(1), 215-220. doi:10.1016/j.apacoust.2007.12.005Oldham, D. J., Egan, C. A., & Cookson, R. D. (2011). Sustainable acoustic absorbers from the biomass. Applied Acoustics, 72(6), 350-363. doi:10.1016/j.apacoust.2010.12.009Berardi, U., & Iannace, G. (2015). Acoustic characterization of natural fibers for sound absorption applications. Building and Environment, 94, 840-852. doi:10.1016/j.buildenv.2015.05.029Mati-Baouche, N., de Baynast, H., Michaud, P., Dupont, T., & Leclaire, P. (2016). Sound absorption properties of a sunflower composite made from crushed stem particles and from chitosan bio-binder. Applied Acoustics, 111, 179-187. doi:10.1016/j.apacoust.2016.04.021Rwawiire, S., Tomkova, B., Militky, J., Hes, L., & Kale, B. M. (2017). Acoustic and thermal properties of a cellulose nonwoven natural fabric (barkcloth). Applied Acoustics, 116, 177-183. doi:10.1016/j.apacoust.2016.09.027López, J. P., El Mansouri, N.-E., Alba, J., Del Rey, R., Mutjé, P., & Vilaseca, F. (2012). ACOUSTIC PROPERTIES OF POLYPROPYLENE COMPOSITES REINFORCED WITH STONE GROUNDWOOD. BioResources, 7(4). doi:10.15376/biores.7.4.4586-4599Arenas, J. P., Rebolledo, J., Del Rey, R., & Alba, J. (2014). Sound Absorption Properties of Unbleached Cellulose Loose-Fill Insulation Material. BioResources, 9(4). doi:10.15376/biores.9.4.6227-6240Reixach, R., Del Rey, R., Alba, J., Arbat, G., Espinach, F. X., & Mutjé, P. (2015). Acoustic properties of agroforestry waste orange pruning fibers reinforced polypropylene composites as an alternative to laminated gypsum boards. Construction and Building Materials, 77, 124-129. doi:10.1016/j.conbuildmat.2014.12.041Del Rey, R., Alba, J., Ramis, J., & Sanchís, V. J. (2011). Nuevos materiales absorbentes acústicos obtenidos a partir de restos de botellas de plástico. Materiales de Construcción, 61(304), 547-558. doi:10.3989/mc.2011.59610Ramis, J., Alba, J., Del Rey, R., Escuder, E., & Sanchís, V. J. (2010). Nuevos materiales absorbentes acústicos basados en fibra de kenaf. Materiales de Construcción, 60(299), 133-143. doi:10.3989/mc.2010.50809Ingard, K. U., & Dear, T. A. (1985). Measurement of acoustic flow resistance. Journal of Sound and Vibration, 103(4), 567-572. doi:10.1016/s0022-460x(85)80024-9Dragonetti, R., Ianniello, C., & Romano, R. A. (2011). Measurement of the resistivity of porous materials with an alternating air-flow method. The Journal of the Acoustical Society of America, 129(2), 753-764. doi:10.1121/1.3523433Rey, R. del, Alba, J., Arenas, J. P., & Ramis, J. (2013). Technical Notes: Evaluation of Two Alternative Procedures for Measuring Airflow Resistance of Sound Absorbing Materials. Archives of Acoustics, 38(4), 547-554. doi:10.2478/aoa-2013-0064Rey, R. del, Alba, J., Arenas, J. P., & Sanchis, V. J. (2012). An empirical modelling of porous sound absorbing materials made of recycled foam. Applied Acoustics, 73(6-7), 604-609. doi:10.1016/j.apacoust.2011.12.009Delany, M. E., & Bazley, E. N. (1970). Acoustical properties of fibrous absorbent materials. Applied Acoustics, 3(2), 105-116. doi:10.1016/0003-682x(70)90031-

Modelización del ruido transmitido por flancos en la edificación en nuevas soluciones constructivas

El ruido transmitido por flancos laterales en edificación es uno de los problemas importantes en su aislamiento acústico, por lo que es conveniente incorporar nuevas soluciones constructivas que permitan abrir el abanico de posibilidades. En este trabajo de Tesis se aborda ese problema. En primer lugar se realiza una revisión importante de técnicas y modelos de medición y predicción del comportamiento acústico de materiales que pudiesen ser susceptibles de usarse en edificación. En esta línea nos hemos centrado sobre todo en dos posibilidades: materiales para usarlos como absorbentes acústicos y materiales para utilizarlos como lámina elástica en un suelo flotante. Se han estudiado varios tipos de materiales, sobre todo materiales reciclados o de fibras naturales, de los que se han obtenido sus características necesarias para valorar si son absorbentes acústicos, e incluso se han obtenido modelos propios de nuevos materiales. También se estudian diferentes reciclados y láminas valorando si son eficientes en un suelo flotante. Se presenta, pues, un estudio de nuevos materiales para edificación que permita aumentar la variedad o que sirva para reutilizar o reciclar otros productos o deshechos. Además, todo esto, estudiando la incertidumbre del ensayo en cada caso. Otro bloque importante de la tesis lo conforma la puesta en marcha y validación de una técnica de medida "in situ" de las transmisiones laterales. Actualmente no existe ninguna técnica normalizada y sólo existen ensayos normalizados en laboratorio para ciertas soluciones constructivas. Se han medido cientos de configuraciones de uniones diferentes, combinando conexiones rígidas y elásticas de unión, y valorando también el efecto del suelo flotante. Se ha estudiado también la incertidumbre de este tipo de ensayos y en qué condiciones son válidos los resultados del ensayo. Con toda la información obtenida, se han obtenido algunas fórmulas ajustadas y diferentes conclusiones respecto a ciertas uniones.Rey Tormos, RMD. (2009). Modelización del ruido transmitido por flancos en la edificación en nuevas soluciones constructivas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6882Palanci

Proposal a empirical model for absorbent acoustical materials

Los materiales absorbentes acústicos son cada vez más importantes en diferentes ámbitos: acústica en la construcción, automoción, aire acondicionado, etc. Existen diferentes modelos para predecir el comportamiento acústico de materiales. Algunos de estos se basan en el ajuste de datos experimentales a una serie de fórmulas empíricas que permiten la predicción en un rango razonable. Además, la norma UNE-EN 12354-6 permite la predicción de la absorción sonora de cualquier material absorbente fibroso con las fórmulas propuestas por Delany & Bazley. En este trabajo se realiza una revisión de los diferentes modelos para predecir el comportamiento de materiales absorbentes acústicos y se realiza un nuevo ajuste buscando un nuevo modelo que se adapte mejor a todo tipo de materiales absorbentes.Peer Reviewe

Sound-Absorption Properties of Materials Made of Esparto Grass Fibers

[EN] Research on sound-absorbing materials made of natural fibers is an emerging area in sustainable materials. In this communication, the use of raw esparto grass as an environmentally friendly sound-absorbing material is explored. Measurements of the normal-incidence sound-absorption coefficient and airflow resistivity of three different types of esparto from different countries are presented. In addition, the best-fit coefficients for reasonable prediction of the sound-absorption performance by means of simple empirical formulae are reported. These formulae require only knowledge of the airflow resistivity of the fibrous material. The results presented in this paper are an addition to the characterization of available natural fibers to be used as alternatives to synthetic ones in the manufacturing of sound-absorbing materials.This research was funded by CONICYT-FONDECYT, grant number 1171110.Arenas, JP.; Rey Tormos, RMD.; Alba, J.; Oltra, R. (2020). Sound-Absorption Properties of Materials Made of Esparto Grass Fibers. Sustainability. 12(14):1-10. https://doi.org/10.3390/su12145533S1101214Faruk, O., Bledzki, A. K., Fink, H.-P., & Sain, M. (2012). Biocomposites reinforced with natural fibers: 2000–2010. Progress in Polymer Science, 37(11), 1552-1596. doi:10.1016/j.progpolymsci.2012.04.003Pickering, K. L., Efendy, M. G. A., & Le, T. M. (2016). A review of recent developments in natural fibre composites and their mechanical performance. Composites Part A: Applied Science and Manufacturing, 83, 98-112. doi:10.1016/j.compositesa.2015.08.038Asdrubali, F., Schiavoni, S., & Horoshenkov, K. V. (2012). A Review of Sustainable Materials for Acoustic Applications. Building Acoustics, 19(4), 283-311. doi:10.1260/1351-010x.19.4.283Berardi, U., & Iannace, G. (2015). Acoustic characterization of natural fibers for sound absorption applications. Building and Environment, 94, 840-852. doi:10.1016/j.buildenv.2015.05.029Koruk, H., & Genc, G. (2015). Investigation of the acoustic properties of bio luffa fiber and composite materials. Materials Letters, 157, 166-168. doi:10.1016/j.matlet.2015.05.071Ersoy, S., & Küçük, H. (2009). Investigation of industrial tea-leaf-fibre waste material for its sound absorption properties. Applied Acoustics, 70(1), 215-220. doi:10.1016/j.apacoust.2007.12.005Hosseini Fouladi, M., Nor, M. J. M., Ayub, M., & Leman, Z. A. (2010). Utilization of coir fiber in multilayer acoustic absorption panel. Applied Acoustics, 71(3), 241-249. doi:10.1016/j.apacoust.2009.09.003Hosseini Fouladi, M., Ayub, M., & Jailani Mohd Nor, M. (2011). Analysis of coir fiber acoustical characteristics. Applied Acoustics, 72(1), 35-42. doi:10.1016/j.apacoust.2010.09.007Ramis, J., Del Rey, R., Alba, J., Godinho, L., & Carbajo, J. (2014). A model for acoustic absorbent materials derived from coconut fiber. Materiales de Construcción, 64(313), e008. doi:10.3989/mc.2014.00513Oldham, D. J., Egan, C. A., & Cookson, R. D. (2011). Sustainable acoustic absorbers from the biomass. Applied Acoustics, 72(6), 350-363. doi:10.1016/j.apacoust.2010.12.009Yang, W., & Li, Y. (2012). Sound absorption performance of natural fibers and their composites. Science China Technological Sciences, 55(8), 2278-2283. doi:10.1007/s11431-012-4943-1Tang, X., Zhang, X., Zhang, H., Zhuang, X., & Yan, X. (2018). Corn husk for noise reduction: Robust acoustic absorption and reduced thickness. Applied Acoustics, 134, 60-68. doi:10.1016/j.apacoust.2018.01.012Berardi, U., Iannace, G., & Di Gabriele, M. (2017). The Acoustic Characterization of Broom Fibers. Journal of Natural Fibers, 14(6), 858-863. doi:10.1080/15440478.2017.1279995Lim, Z. Y., Putra, A., Nor, M. J. M., & Yaakob, M. Y. (2018). Sound absorption performance of natural kenaf fibres. Applied Acoustics, 130, 107-114. doi:10.1016/j.apacoust.2017.09.012Malawade, U. A., & Jadhav, M. G. (2020). Investigation of the Acoustic Performance of Bagasse. Journal of Materials Research and Technology, 9(1), 882-889. doi:10.1016/j.jmrt.2019.11.028Gomez, T. S., Navacerrada, M. A., Díaz, C., & Fernández-Morales, P. (2020). Fique fibres as a sustainable material for thermoacoustic conditioning. Applied Acoustics, 164, 107240. doi:10.1016/j.apacoust.2020.107240Othmani, C., Taktak, M., Zein, A., Hentati, T., Elnady, T., Fakhfakh, T., & Haddar, M. (2016). Experimental and theoretical investigation of the acoustic performance of sugarcane wastes based material. Applied Acoustics, 109, 90-96. doi:10.1016/j.apacoust.2016.02.005Or, K. H., Putra, A., & Selamat, M. Z. (2017). Oil palm empty fruit bunch fibres as sustainable acoustic absorber. Applied Acoustics, 119, 9-16. doi:10.1016/j.apacoust.2016.12.002Taban, E., Khavanin, A., Faridan, M., Samaei, S. E., Samimi, K., & Rashidi, R. (2019). Comparison of acoustic absorption characteristics of coir and date palm fibers: experimental and analytical study of green composites. International Journal of Environmental Science and Technology, 17(1), 39-48. doi:10.1007/s13762-019-02304-8Putra, A., Or, K. H., Selamat, M. Z., Nor, M. J. M., Hassan, M. H., & Prasetiyo, I. (2018). Sound absorption of extracted pineapple-leaf fibres. Applied Acoustics, 136, 9-15. doi:10.1016/j.apacoust.2018.01.029Yun, B. Y., Cho, H. M., Kim, Y. U., Lee, S. C., Berardi, U., & Kim, S. (2020). Circular reutilization of coffee waste for sound absorbing panels: A perspective on material recycling. Environmental Research, 184, 109281. doi:10.1016/j.envres.2020.109281Zhang, J., Shen, Y., Jiang, B., & Li, Y. (2018). Sound Absorption Characterization of Natural Materials and Sandwich Structure Composites. Aerospace, 5(3), 75. doi:10.3390/aerospace5030075Kusno, A., Sakagami, K., Okuzono, T., Toyoda, M., Otsuru, T., Mulyadi, R., & Kamil, K. (2019). A Pilot Study on the Sound Absorption Characteristics of Chicken Feathers as an Alternative Sustainable Acoustical Material. Sustainability, 11(5), 1476. doi:10.3390/su11051476Delany, M. E., & Bazley, E. N. (1970). Acoustical properties of fibrous absorbent materials. Applied Acoustics, 3(2), 105-116. doi:10.1016/0003-682x(70)90031-9Berardi, U., & Iannace, G. (2017). Predicting the sound absorption of natural materials: Best-fit inverse laws for the acoustic impedance and the propagation constant. Applied Acoustics, 115, 131-138. doi:10.1016/j.apacoust.2016.08.012Miki, Y. (1990). Acoustical properties of porous materials. Modifications of Delany-Bazley models. Journal of the Acoustical Society of Japan (E), 11(1), 19-24. doi:10.1250/ast.11.19Attenborough, K. (1982). Acoustical characteristics of porous materials. Physics Reports, 82(3), 179-227. doi:10.1016/0370-1573(82)90131-4Dunn, I. P., & Davern, W. A. (1986). Calculation of acoustic impedance of multi-layer absorbers. Applied Acoustics, 19(5), 321-334. doi:10.1016/0003-682x(86)90044-7Garai, M., & Pompoli, F. (2005). A simple empirical model of polyester fibre materials for acoustical applications. Applied Acoustics, 66(12), 1383-1398. doi:10.1016/j.apacoust.2005.04.008Rey, R. del, Alba, J., Arenas, J. P., & Sanchis, V. J. (2012). An empirical modelling of porous sound absorbing materials made of recycled foam. Applied Acoustics, 73(6-7), 604-609. doi:10.1016/j.apacoust.2011.12.009Arenas, J. P., Rebolledo, J., Del Rey, R., & Alba, J. (2014). Sound Absorption Properties of Unbleached Cellulose Loose-Fill Insulation Material. BioResources, 9(4). doi:10.15376/biores.9.4.6227-6240Silva, C. C. B. da, Terashima, F. J. H., Barbieri, N., & Lima, K. F. de. (2019). Sound absorption coefficient assessment of sisal, coconut husk and sugar cane fibers for low frequencies based on three different methods. Applied Acoustics, 156, 92-100. doi:10.1016/j.apacoust.2019.07.001Sair, S., Mansouri, S., Tanane, O., Abboud, Y., & El Bouari, A. (2019). Alfa fiber-polyurethane composite as a thermal and acoustic insulation material for building applications. SN Applied Sciences, 1(7). doi:10.1007/s42452-019-0685-zMaghchiche, A., Haouam, A., & Immirzi, B. (2013). Extraction and Characterization of Algerian Alfa Grass Short Fibers (Stipa Tenacissima). Chemistry & Chemical Technology, 7(3), 339-344. doi:10.23939/chcht07.03.339Nadji, H., Diouf, P. N., Benaboura, A., Bedard, Y., Riedl, B., & Stevanovic, T. (2009). Comparative study of lignins isolated from Alfa grass (Stipa tenacissima L.). Bioresource Technology, 100(14), 3585-3592. doi:10.1016/j.biortech.2009.01.074Belkhir, S., Koubaa, A., Khadhri, A., Ksontini, M., & Smiti, S. (2012). Variations in the morphological characteristics of Stipa tenacissima fiber: The case of Tunisia. Industrial Crops and Products, 37(1), 200-206. doi:10.1016/j.indcrop.2011.11.021Ingard, K. U., & Dear, T. A. (1985). Measurement of acoustic flow resistance. Journal of Sound and Vibration, 103(4), 567-572. doi:10.1016/s0022-460x(85)80024-9Rey, R. del, Alba, J., Arenas, J. P., & Ramis, J. (2013). Technical Notes: Evaluation of Two Alternative Procedures for Measuring Airflow Resistance of Sound Absorbing Materials. Archives of Acoustics, 38(4), 547-554. doi:10.2478/aoa-2013-0064Nelder, J. A., & Mead, R. (1965). A Simplex Method for Function Minimization. The Computer Journal, 7(4), 308-313. doi:10.1093/comjnl/7.4.308Lagarias, J. C., Reeds, J. A., Wright, M. H., & Wright, P. E. (1998). Convergence Properties of the Nelder--Mead Simplex Method in Low Dimensions. SIAM Journal on Optimization, 9(1), 112-147. doi:10.1137/s105262349630347

Estrategia para evaluar la competencia transversal “Aprendizaje Permanente” en la asignatura Transductores e Instrumentación Acústica

[EN] Use the learning in a strategically, autonomously and flexibly way, throughout life, according to the pursued objective is one of the transversal competences that is control item of the subject entitled "Transducers and Acoustic Instrumentation". This subject belong to the Bachelor's Degree in Engineering of Telecommunications Systems, Sound and Image. During the 2015-2016 academic year, we have initiated and presented strategies for start up the mechanisms in order to work and evaluate this transversal competence. We have defined a number of improvements for the 2016-2017 academic year. These improvements have based on the results obtained during the 2015-2016 academic year. This paper shows the evolution and valuation of the last two academic years[ES] Utilizar el aprendizaje de manera estratégica, autónoma y flexible, a lo largo de toda la vida, en función del objetivo perseguido es una de las competencias transversales que es punto de control de la asignatura “Transductores e Instrumentación Acústica” de la titulación del Grado en Ingeniería de Sistemas de Telecomunicación, Sonido e Imagen. En el curso 2015-2016 se iniciaron y presentaron estrategias de puesta en marcha de mecanismos para trabajarla en la asignatura y evaluarla. En base a los resultados obtenidos se definieron una serie de mejoras para el curso 2016-2017. En este trabajo se muestra la evolución y valoración de los dos cursos.Alba Fernández, J.; Rey Tormos, RMD. (2017). Estrategia para evaluar la competencia transversal “Aprendizaje Permanente” en la asignatura Transductores e Instrumentación Acústica. En In-Red 2017. III Congreso Nacional de innovación educativa y de docencia en red. Editorial Universitat Politècnica de València. 1032-1043. https://doi.org/10.4995/INRED2017.2017.6859OCS1032104

Working on the Transversal Competence "Knowledge of contemporary problems" in the Master of Acoustic Engineering

[EN] The subject Building Acoustics, of the Master's Degree in Acoustic Engineering, of the Escola Politècnica Superior de Gandia, is checkpoint of the Transversal Competence “knowledge of contemporary problems” from five years ago. This paper shows how it has been the set up using technical reports, the decisions we have taken and approach, the materials developed and their evolution, the results obtained and conclusions. It is also presented a SWOT analysis about the acquisition of this competence.[ES] La asignatura Aislamiento Acústico en la Edificación, del Máster en Ingeniería Acústica, de la Escuela Politécnica Superior de Gandia, es punto de control de la Competencia Transversal “Conocimientos de problemas contemporáneos” desde hace seis años. En este trabajo se muestra cómo se ha puesto en marcha utilizando la redacción de informes técnicos, las decisiones tomadas y su enfoque, los materiales desarrollados y su evolución, los resultados obtenidos y conclusiones. Se presenta un análisis DAFO final sobre la adquisición de esta competencia.Alba Fernández, J.; Rey Tormos, RMD. (2022). Trabajando la Competencia Transversal “Conocimientos de problemas contemporáneos” en el Máster de Ingeniería Acústica. Editorial Universitat Politècnica de València. 348-359. https://doi.org/10.4995/INRED2022.2022.1589634835

Competencia transversal “Aprendizaje Permanente”: experiencia en la asignatura Transductores e Instrumentación Acústica

[EN] Lifelong learning is one of the transversal competences that the Polytechnic University of València aims to prove. The “Acoustic Transducers and Instrumentation” subject of Engineering Degree in Telecommunications Systems, Sound and Image degree is a checkpoint of that competence. During the 2015-2016 academic year some mechanisms have been put in place in order to work it in the subject and evaluate it. In this work the experience of this year is summarized, and strengths and weakness of the initial proposal are evaluated, thinking of further improvements.[ES] El aprendizaje permanente es una de las competencias transversales que la Universitat Politécnica de Valencia pretende acreditar. La asignatura “Transductores e Instrumentación Acústica” de la titulación del Grado en Ingeniería de Sistemas de Telecomunicación, Sonido e Imagen es punto de control de dicha competencia. En el curso 2015-2016 se han puesto en marcha mecanismos para trabajarla en la asignatura y para poder evaluarla. En este trabajo se resume la experiencia de este curso, y se valoran fortalezas y debilidades de la propuesta inicial, pensando en posibles mejoras para el próximo curso.Alba Fernández, J.; Rey Tormos, RMD. (2016). Competencia transversal “Aprendizaje Permanente”: experiencia en la asignatura Transductores e Instrumentación Acústica. En In-Red 2016. II Congreso nacional de innovación educativa y docencia en red. Editorial Universitat Politècnica de València. https://doi.org/10.4995/INRED2016.2016.436

Medida de la temperatura con una botella

[EN] The purpose of this paper is the experimental determination of temperature using a bottle as the only means. The bottle is a resonator of Helmholtz, which is the acoustic simpler system. Its behavior depends directly on the speed of propagation of the sound in the air and. This speed depends on temperature. In this paper are proposed two different procedures to determine the temperature easily.[ES] El objeto de este trabajo es la determinación experimental de la temperatura utilizando como único medio una botella. La botella es un resonador de Helmholtz, que es el sistema acústico más sencillo. Su comportamiento depende directamente de la velocidad de propagación del sonido en el aire y ésta, a su vez, de la temperatura. Se proponen dos procedimientos diferentes que permiten obtener la temperatura de forma sencilla.Alba Fernández, J.; Rey Tormos, RMD. (2014). Medida de la temperatura con una botella. Revista de Acústica. 45(3-4):7-10. http://hdl.handle.net/10251/56783S710453-

The Environmental Impacts of Disposable Nonwoven Fabrics during the COVID-19 Pandemic: Case Study on the Francesc de Borja Hospital

[EN] Hospitals generate huge amounts of nonwoven residues daily. This paper focused on studying the evolution of nonwoven waste generated in the Francesc de Borja Hospital, Spain, over the last few years and its relation to the COVID-19 pandemic. The main objective was to identify the most impacting pieces of nonwoven equipment in the hospital and to analyze possible solutions. The carbon footprint of the nonwoven equipment was studied through a life-cycle assessment. The results showed an apparent increase in the carbon footprint in the hospital from 2020. Additionally, due to the higher annual volume, the simple nonwoven gown used primarily for patients had a higher carbon footprint over a year than the more sophisticated surgical gowns. It can be concluded that developing a local circular economy strategy for medical equipment could be the solution to avoid the enormous waste generation and the carbon footprint of nonwoven production.: This research was funded by the Fisabio Fundation under the 2020 call for grants for preparatory actions and joint innovation projects between the research staff of the Universitat Politècnica de València and professionals of the Fundació per al Foment de la Investigació Sanitària i Biomèdica de la Comunitat Valenciana, grant number A45, project name Compensación de la generación de residuos textiles hospitalarios generados por la crisis de la COVID-19 con un modelo de economía circularQuintana-Gallardo, A.; Del Rey, R.; González-Conca, S.; Guillén Guillamón, IE. (2023). The Environmental Impacts of Disposable Nonwoven Fabrics during the COVID-19 Pandemic: Case Study on the Francesc de Borja Hospital. Polymers. 15(5). https://doi.org/10.3390/polym1505113015

Evaluation of two alternative procedures for measuring airflow resistance of sound absorbing materials

[EN] It is well known that sound absorption and sound transmission properties of open porous materials are highly dependent on their airflow resistance values. Low values of airflow resistance indicate little resistance for air streaming through the porous material and high values are a sign that most of the pores inside the material are closed. The laboratory procedures for measuring airflow resistance have been stan- dardized by several organizations, including ISO and ASTM for both alternate flow and continuous flow. However, practical implementation of these standardized methods could be both complex and expensive. In this work, two indirect alternative measurement procedures were compared against the alternate flow standardized technique. The techniques were tested using three families of eco-friendly sound absorbent materials: recycled polyurethane foams, coconut natural fibres, and recycled polyester fibres. It is found that the values of airflow resistance measured using both alternative methods are very similar. There is also a good correlation between the values obtained through alternative and standardized methods.This project has been made possible thanks to the FONDECYT Project 1110605 and the grant GV/2012/066 Projects I+D for emerging research groups. The authors would like to thank Dr. Luis Godinho from the Department of Civil Engineering of University of Coimbra (Portugal) for his help with the experimental work and the ISO data reported in Table 1 of this paper.Rey Tormos, RMD.; Alba Fernández, J.; Arenas, JP.; Ramis Soriano, J. (2013). Evaluation of two alternative procedures for measuring airflow resistance of sound absorbing materials. Archives of Acoustics. 38(4):547-554. https://doi.org/10.2478/aoa:2013-0064S54755438