Airborne ultrasonic vortex generation using flexible ferroelectrets

Cellular ferroelectrets exhibit interesting electromechanical- acoustical characteristics. Their recent appearance and remarkable properties open up new possibilities for the design and development of ultrasonic transducers. In particular, the feasibility of fabricating ultrasonic vortex generators using ferroelectret films is demonstrated in this work. To this end, a transducer prototype was built by gluing the material onto a tangential-helical surface (outer diameter: 40 mm, pitch: 3.45 mm). Experimental results agree well with the theoretical estimation of the pressure and phase of the acoustic field in the near field and far field, which corroborates the potential of ferroelectrets to customize special acoustic fields. Furthermore, the proposed fabrication procedure is inexpensive and represents a new alternative for exploring and analyzing the special characteristics of acoustical helical wavefront

Measuring material thickness changes through tri-aperture digital speckle pattern interferometry

A configuration for the measurement of thickness changes in materials through one-shot digital speckle pattern interferometry (DSPI) was developed. The phase maps calculation was made by adding carrier fringes by the multiple aperture principle and Fourier Transform Method (FTM). With this setup, interferometry configurations verified that the simultaneous and instantaneous visualization of two opposite faces of a surface is possible. In addition, the combination of the simultaneous results obtained from both sides of the material makes it possible to determine displacements with greater sensitivity or to identify changes in their thickness. The validation and demonstrative tests were carried out with a 1-mm-thick aluminum plate with a 5-mm diameter through hole coated. Thickness changes to 2 μm were measured. © 2023 Society of Photo-Optical Instrumentation Engineers (SPIE)

Últimas traducciones en lengua asturiana de textos literarios ingleses

En los últimos tiempos, la producción de textos literarios en lIingua asturiana ha visto incrementado su número de publicaciones de una manera tan fértil como sorprendente. Ni los más optimistas esperaban el espectacular crecimiento del mercado editorial de textos escritos en la lengua vemácula de Asturias. Paralelo a este inesperado crecimiento, ha proliferado (especialmente en estos últimos dos años) la oferta editorial de textos literarios traducidos de lenguas extranjeras al asturian

Impact of aerosol microphysical properties on mass scattering cross sections

We assessed the sensitivity of simulated mass scattering cross sections (αλsca [m2/g]) of three aerosol perturbed particle microphysical properties and derived constraintspecies to on these microphysical properties, suitable for the north-western Mediterranean basin, from a comparison between code calculations and observations. In detail, we calculated αλsca of mineral dust,organic carbon and sulfate at three wavelengths in the visible range with a T-matrix optical code, considering ±20%perturbations on size distribution, refractive index and mass density, and spheroids with two different axial ratios as shape perturbations. Then, we compared the simulation results with a set of observed αλsca of mineral dust, aged organics and ammonium sulfate sources provided by the Institute of Environmental Assessment and Water Research (IDAEA-CSIC) and representative of the north-western Mediterranean Basi

From air quality to climate: Impact of aerosol sources on optical properties at urban, regional and continental levels in the north-western Mediterranean

Further research is needed to reduce the existing uncertainties on the effect that specific aerosol sources have on radiative forcing, thus supporting the assessment of future mitigation strategies which should be focused on both air quality and climate, and not acting separately. This study presents a new approach aimed at quantifying the mass scattering and absorption efficiencies (MSE and MAE) of different aerosol sources at urban (Barcelona-BCN), regional (Montseny-MSY) and remote (Montsec-MSA) background sites in the northwestern (NW) Mediterranean. An analysis of source apportionment to the measured scattering and absorption coefficients was performed by means of a multilinear regression (MLR) model during 2010–2014 at BCN and MSY and during 2011–2014 at MSA. The source contributions to PM10 mass, identified by means of the Positive Matrix Factorization (PMF) model, were used as dependent variables in the MLR model in order to take into account the internal mixing state of atmospheric aerosols. Seven aerosol sources were obtained at MSA and MSY and 8 sources at BCN. Mineral, Aged marine, Ammonium sulfate, Ammonium nitrate and V-Ni bearing sources were common at the three sites. Traffic, Industrial/metallurgy and Road-resuspension were isolated at BCN, whereas Industrial/Traffic and Aged organics were solely identified at MSY and MSA. The highest MSE were found for Ammonium sulfate (4.5 and 10.7 m2 g−1), Ammonium nitrate (8.8 and 7.8 m2 g−1) and V-Ni (8 and 3.5 m2 g−1) at MSY and MSA respectively, dominating the scattering throughout the year with marked seasonal trends. V-Ni bearing, originated mainly from shipping emissions, simultaneously contributed to both scattering and absorption being the second most efficient absorptive source in BCN (0.9 m2 g−1). The Traffic source at BCN and the equivalent Industrial/Traffic at MSY and MSA mainly governed the light absorption and exhibited the highest MAE (1.7, 0.9 and 0.2 m2 g−1, respectively). Sources predominantly composed by fine and relatively dark particles such as Industrial/Traffic, Aged organics and V-Ni were simultaneously characterized with low single scattering albedo (SSA) and high scattering Angstrom exponent (SAE). Conversely, Mineral and Aged marine showed the highest SAE and the lowest SSA, being scattering the dominant process in the light extinction. The good agreement between modeled and measured optical properties allowed for the reconstruction of scattering, absorption and SSA time series by means of the PMF-MLR technique for the period 2004–2014 at MSY. Significant decreasing trends were found for the modeled scattering and absorption (−4.6 and −4.1 % y−1) coefficients. Interestingly, the observed reduction in the SSA (−0.11 % y−1) might suggests a less effectiveness of the air quality strategies focused on reducing pollutants containing black carbon (BC) particles, which highly contribute to light absorption and thus climate warming.This work was supported by the MINECO (Spanish Ministry of Economy and Competitiveness) and FEDER funds under the PRISMA project (CGL2012-39623-C02/00), by the MAGRAMA (Spanish Ministry of Agriculture, Food and Environment) and by the Generalitat de Catalunya (AGAUR 2014 SGR33 and the DGQA). This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 654109. Marco Pandolfi is funded by a Ramón y Cajal Fellowship (RYC-2013-14036) awarded by the MINECO. The authors would like to express their gratitude to D. C. Carslaw and K. Ropkins for providing the OpenAir software used in this paper (Carslaw and Ropkins, 2012; Carslaw, 2012).Peer reviewe

Cámaras anecoicas acústicas de bajo costo y fácil implementación

In this paper, the design, construction and verification of a low-cost and easy-to-install anechoic chamber are described. The chamber is constructed with affordable, local materials. The quality, according to the deviation from the inverse square law, complies with ISO 3745. The working dimensions of the chamber are 1.94 m long x 1.91 m wide x 1.84 m high. The nominal cutoff frequency is 400 Hz. The cost per square meter of the effective finished volume is 200 USD. With this design, small- and medium-sized enterprises are able to build anechoic chambers with a small investment, adding value to their products through characterization and subsequent mitigation, conditioning or amplification, as necessary, of emitted sound or noise. This study also contributes to the development and appropriation of knowledge in acoustics, a branch of physics of emerging importance in developing countries.En este trabajo se presenta el diseño, construcción y evaluación de una cámara anecoica de bajo costo usando materiales provistos por el mercado local; tales como: espuma de poliuretano, tubos de acero, fibra de vidrio, placas de fibrocemento, placas de madera aglomerada, etc. La cámara posee dimensiones de trabajo de 1,94 m de largo x 1,91 m de ancho x 1,84 m de alto y frecuencia de corte nominal de 400 Hz, a partir de la cual la cámara recrea condiciones de espacio al aire libre en cuanto a ondas sonoras se refiere. Pudo constatarse que la cámara cumple con la desviación máxima permitida de la ley del inverso cuadrado según la norma ISO 3745. El desarrollo de este tipo de proyectos es de vital importancia para la evolución tecnológica de países emergentes, ya que estimula la actividad de los investigadores y da posibilidades a la industria local para el desarrollo de procesos y productos en temas relacionados con la Acústica, temática poco desarrollada en países en vía de desarrollo

Propuesta para calcular la energía firme para el cargo por confiabilidad – ENFICC de centrales hidroeléctricas dentro del mercado eléctrico colombiano

En este trabajo se analizó el comportamiento del software HIDENFICC, el cual se utiliza para calcular la Energía Firme para el Cargo por Confiabilidad – ENFICC, bajo diferentes escenarios de sensibilidad a sus principales parámetros de funcionamiento como lo son cambio en volumen útil, factor de conversión - FC, series hidrológicas medias mensuales, indisponibilidad histórica forzada - IHF. Se encontró que el software cuando se utiliza para la simulación de centrales hidroeléctrica las opera como si fueren filo de agua, consume su embalse rápidamente y no almacena para los periodos críticos. De igual forma se encontró que el modelo solo utiliza un valor de factor conversión, denominado F.C. mediano e invariable con los cambios de nivel de embalse, lo que se considera una aproximación que se aleja de la realidad considerando que dicho factor depende directamente del salto hidráulico de la central y por ende del nivel del embalse. Se observó su comportamiento ante la simulación con una serie sintética de caudales generada a partir de un modelo lluvia escorrentía y utilizando los resultados de precipitación de un modelo de circulación global encontrando que dada a su baja optimización, no es capaz de reflejar los cambios en la varianza de los datos y por ende en algunos casos incrementa incorrectamente la energía firme del proyecto evaluado. Por último se presenta una propuesta más acorde a la operación “real” de las centrales hidroeléctricas de cómo calcular la energía firme bajo la ayuda de un modelo en RNO o regla normal de operación que considera la variación del F.C. con el embalse, volúmenes característicos y una serie de caudales diarios, manteniendo los demás parámetros.Abstract: In this work the behavior of the HIDENFICC software was analyzed, which is used to calculate the Firm Energy for the Reliability Charge -ENFICC, under different sensitivity scenarios to its main operating parameters such as change in useful volume, conversion factor -FC, monthly hydrological series, forced historical unavailability -IHF. It as found that the software when used for simulation of hydroelectric plants operates them as if they are “run of river”, it consumes its reservoir quickly and it does not store for the critical periods. In the same way, it was found that the model only uses a value of factor conversion, denominated medium and invariable F.C.with the changes of reservoir level, which is considered an approximation that moves away from the reality considering that this factor depends directly on the hydraulic jump Of the central and therefore of the level of the reservoir. It was observed its behavior in the simulation with a synthetic series of flows generated from a rainfall runoff model and using the precipitation results of a global circulation model, finding that due to its low optimization, it is not able to reflect the hanges in the Variance of the data and therefore in some cases improperly increases the firm energy of the evaluated project. Finally, a proposal more in line with the "real" operation of hydroelectric power plants is presented on how to calculate firm energy under the aid of an RNO model or normal operating rule that considers the variation of the F.C. With the reservoir, characteristic volumes and a series of daily flows, maintaining the other parametersMaestrí