1,998 research outputs found

    Detection of Musical Notes Using a Polyphonic Pitch Tracking Embedded System

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    Detection of polyphonic notes using embedded systems is a field that has not been explored. This article describes a polyphonic tracking embedded system that can detect on real time single and multiple musical notes, as well as their time duration. The solution was designed on an embedded system with a Cortex M-7 core as processor. This was achieved with an algorithm using fast Fourier transform iterating on two buffers in coordination with the direct memory access peripheral. The proposed embedded system was able to detect multiple musical notes on real time. Future works could use the results of this design and export them to a real music editing format.ITESO, A. C

    Optimization of pulsed thermoelectric materials using simulated annealing and non-linear finite elements

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    [EN] The objective of this work is to determine the optimal shape, gains and duration of an electric pulse applied to a Peltier cell, together with the length of the thermoelectric to maximize cooling while min- imizing electric consumption. For this purpose, a fully coupled, multiphysics, dynamic finite-element model, which solves for the thermal, electric and mechanical fields is used. Because of the demanding computing requirements of the optimization process, a special mesh is designed and a convergence anal- ysis is carried out before using the multiphysics model. The highly non-linear optimization is done by simulated annealing, a heuristic algorithm in the Markov chain Monte-Carlo family. A preliminary para- metric investigation is presented, analyzing the impact of some of the parameters. The results of this pre- liminary analysis help to understand the effect of the different shapes in the evolution of the cold face temperature. Some of these results are expected and have already been discussed elsewhere, but others can only be explained after further analysis and a full system modeling. Pulse optimization is multiobjec- tive and multiparametric, i.e., it can consider several targets such as maximizing the cooling temperature, the cooling duration or others. The trade-offs between the different targets are studied. In all cases, stres- ses inside the thermoelement are examined at all points, and the pulses must meet the restriction that an equivalent stress is not above the allowable value.This research was partially supported by the grants, Haut-de-France Region (CR Picardie, 120-2015-RDISTRUCT-000010), EU funding (FEDER, RDISTRUCT-000010) for Chaire-de-Mecanique, and Spanish Ministry of Economy and Competitiveness grant CGL2014-59841-P. These supports are gratefully acknowledgedMoreno-Navarro, P.; Pérez-Aparicio, JL.; Gómez-Hernández, JJ. (2017). Optimization of pulsed thermoelectric materials using simulated annealing and non-linear finite elements. Applied Thermal Engineering. 120:603-613. https://doi.org/10.1016/j.applthermaleng.2017.04.036S60361312

    Analytical and multicoupled methods for optimal steady-state thermoelectric solutions

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    [EN] Peltier cells have low efficiency, but they are becoming attractive alternatives for affordable and environmentally clean cooling. In this line, the current article develops closed-form and semianalytical solutions to improve the temperature distribution of Bi2Te3 thermoelements. From the distribution, the main objective of the current work-the optimal electric intensity to maximize cooling-is inferred. The general one-dimensional differential coupled equation is integrated for linear and quadratic geometry of thermoelements, under temperature constant properties. For a general shape, a piece-wise solution based on heat flux continuity among virtual layers gives accurate analytical solutions. For variable properties, another piece-wise solution is developed but solved iteratively. Taking advantage of the formulae, the optimal intensity is directly derived with a minimal computational cost; its value will be of utility for more advanced designs. Finally, a parametric study including straight, two linear, barrel, hourglass and vase geometries is presented, drawing conclusions on how the shape of the thermoelement affects the coupled phenomena. A specially developed coupled and non-linear finite element research code is run taking into account all the materials of the cell and using symmetries and repetitions. These accurate results are used to validate the analytical ones.This work was supported by the Generalitat Valenciana research programmes PROMETEO/2020/016: Applications de Topologic Isolators in Spintronics and Thermoelectricity (TOP-TERM) and BEST/2021/079. The support is gratefully acknowledged.Moreno-Navarro, P.; Pérez-Aparicio, JL.; Gómez-Hernández, JJ. (2022). Analytical and multicoupled methods for optimal steady-state thermoelectric solutions. Coupled Systems Mechanics, an international journal. 11(2):151-166. https://doi.org/10.12989/csm.2022.11.2.15115116611

    Furfural, 5-HMF, acid-soluble lignin and sugar contents in C. ladanifer and E. arborea lignocellulosic biomass hydrolysates obtained from microwave-assisted treatments in different solvents

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    Cistus ladanifer L. and Erica arborea L. are the two most representative shrub species from the Iberian Peninsula. With a view to their valorization, their biomass hydrolysate components, obtained from microwave-assisted treatments with choline chloride/urea - HNO3 10%, N,N-dimethylacetamide/NaHCO3 and N,N-dimethylacetamide/CH3OK as solvents, have been measured using a spectrophotometric method. Concentrations of furfural and 5-(hydroxymethyl)furfural (5-HMF) in the filtrate have been determined after reduction with NaBH4. The production of total sugars, reducing sugars and non-reducing sugars has also been assessed. The obtained results support the choice of microwave-assisted choline chloride/urea deep eutectic solvent in acid media as the preferred method (over the polar aprotic solvent-based alternatives) for the extraction of lignin, furfural, 5-HMF and sugars from C. ladanifer and E. arborea biomass, attaining the best production yields for 60¿min exposure times. Another is the case if the aim of the treatments is to recovery sugars from both shrubs for subsequent enzymatic saccharification: the very low 5-HMF contents resulting from the dimetylacetamide systems (especially is association with CH3OK) make them highly advantageous as compared to the traditional method using NaOH

    Crystallinity of cellulose microfibers derived from Cistus ladanifer and Erica arborea shrubs

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    The effectiveness of the use of cellulose fibers as particulates/composite reinforcers involves the assessment of the crystallinity of such fibers. The aim of the present work is to provide information on the degree of crystallinity of the cellulose microfibers obtained from the stems of Cistus ladanifer and Erica arborea shrubs through two different methods, namely an alkaline treatment and a microwave-assisted deep eutectic solvent (DES) method. The crystallinity indexes (CrI) obtained from X-ray powder diffraction patterns indicated that higher CrI were attained for cellulose obtained from the DES treatment. Complementary information on the degree of crystallinity was also retrieved from attenuated total reflection- Fourier transform infrared spectroscopy (ATR-FTIR) vibrational spectra, scanning electron microscopy (SEM) micrographs, and accessibility data for the DES-treated celluloses from the two species. The crystallinity results for the fibers derived from these two Mediterranean shrubs were within the range of the results for those derived from wood pulp, opening the door to their valorization for cellulose-derived packing applications or for their use as reinforcers in composite materials in combination with other biopolymers

    Use of Aerial Laser Scanning to Assess the Effect on C Sequestration of Oak (Quercus ilex L. subsp. ballota [Desf.]Samp-Q. suber L.) Afforestation on Agricultural Land

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    Conversion of agricultural lands to forest plantations to mitigate rising atmospheric carbon dioxide (CO2) has been proposed, but it depends on accurate estimation of the on-site carbon (C) stocks distribution. The use of aerial laser scanning (ALS) data is a rapidly evolving technology for the quantification of C stocks. We evaluated the use of allometric models together with high-density ALS data for the quantification of biomass and soil C stocks in a 14-year-old Quercus ilex and Q. suber plantation in Southwestern Spain. In 2010, a field survey was performed and tree dasometric and biomass variables were measured. Forty-five soil profiles (N = 180 soil samples) were taken systematically and the soil organic C content (SOC) was determined. Biomass and soil organic C values were regressed against individual dasometric variables and total tree height was used as a predictor variable. Aerial laser scanning data were acquired with a point density of 12 points m−2. Relationships among ALS metrics and tree height were determined using stepwise regression models and used in the allometric models to estimate biomass and SOC C stocks. Finally, a C stock map of the holm-cork oak cover in the study area was generated. We found a tree total biomass of 27.9 kg tree−1 for holm oak and 41.1 kg tree−1 for cork oak. In the holm oak plantation, the SOC content was 36.90 Mg ha−1 for the layer 0–40 cm (SOC40) under the tree crown and 29.26 Mg ha−1 for the inter-planted area, with significant differences from the reference agricultural land (33.35 Mg ha−1). Linear regression models were developed to predict the biomass and SOC at the tree scale, based on tree height (R2 >0.72 for biomass, and R2 >0.62 for SOC). The overall on-site C stock in the holm-cork oak plantation was 35.11 Mg ha−1, representing a net C stock rise of 0.47 Mg ha−1 yr−1. The ALS data allows a reliable estimation of C stocks in holm and cork oak plantations and high-resolution maps of on-site C stocks are useful for silvicultural planning. The cost of ALS data acquisition has decreased and this method can be generalised to plantations of other Mediterranean species established on agricultural lands at regional scales. However, an increase of filed data and the availability of local biomass and, in particular, SOC will improve accurate quantification of the C stocks from allometric equations, and extrapolation to large planted areas

    Escoliosis experimental por lesión vascular metamérica a nivel lumbar

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    Se ha realizado un estudio experimental en 25 híbridos de conejo californiano con conejo blanco gigante neozelandés de 37 ± 3 días, lesionando la vascularización metamé- rica que irriga las vértebras lumbares con el propósito de alterar indirectamente el desarrollo de los cartílagos neurocentrales (CNC). La lesión vascular se produjo por la destrucción unilateral a dos o tres niveles de los vasos metaméricos de las vértebras L3 a L5. Las columnas vertebrales fueron disecadas, realizándose estudios radiológicos, macroscópicos e histológicos. Se obtuvieron curvas escolióticas (13 ±4°) de convexidad hacia el lado contrario al intervenido, con rotación de los cuerpos vertebrales (12 ± 5o ) hacia la concavidad de la curva, y rectificación de la cifosis lumbar fisiológica de los conejos (5 ±7°). El ascpecto macroscópico de las curvas era similar al que se observa en la escoliosis idiopática humana. Estos hallazgos apoyan la idea de que una alteración del desarrollo del CNC por déficit vascular, de forma unilateral, es capaz de inducir la aparición de una escoliosis.We have damaged the vascular supply to the right neurocentral cartilage (NCC) to 25 growing rabbits, in order to induce scoliosis. The employed technique was the section of the right metameric artery and vein at two or three levels in the lumbar region (L3 to L5). The spine was studied histologically macroscopically and radiologically. We got slight curves (13 ±4°) with the convexity towards the opposite side to the operated zone, and with rotation (12 ±5°) and lordosis (5 ± 7°). These lesions are similar to human idiopathic scoliosis and may be explained because of the NCC's physiological properties. Those findings support the idea that any mechanic, metabolic or endocrine alteration that cause damage to the NCC or to its vascularization, unilaterally, will induced a scoliosis development

    Sugar beet agronomic performance evolution in NW Spain in future scenarios of climate change

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    Changes in environmental conditions resulting from Climate Change are expected to have a major impact on crops. In order to foresee adaptation measures and to minimize yield decline, it is necessary to estimate the effect of those changes on the evapotranspiration and on the associated irrigation needs of crops. In the study presented herein, future conditions extracted from RCP4.5 scenario of IPCC, particularized for Castilla-y-León (Spain), were used as inputs for FAO crop simulation model (AquaCrop) to estimate sugar beet agronomic performance in the medium-term (2050 and 2070). A regional analysis of future trends in terms of yield, biomass and CO2 sequestration was carried out. An annual ET0 increase of up to 200 mm was estimated in 2050 and 2070 scenarios, with ETc increases of up to 40 mm/month. At current irrigation levels, temperature rise would be accompanied by a 9% decrease in yield and a ca. 6% decrease in assimilated CO2 in the 2050 and 2070 scenarios. However, it is also shown that the implementation of adequate adaptation measures, in combination with a more efficient irrigation management, may result in up to 17% higher yields and in the storage of between 9% and 13% higher amounts of CO2

    Nuevos datos sobre la estratigrafía de subsuelo del acuífero de Torrevieja (Alicante): implicaciones en el modelo conceptual de funcionamiento.

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    El análisis estratigráfico de sondeos de investigación realizados en el acuifera de Torrevieja pone de manifiesto la coincidencia de las unidades hidrogeológicas con las estratigráficas y permite una mayor precisión en la definición de las primeras al poder constatar que las variaciones internas dentro de las unidades estratigráficas tienen reflejo en la geometria de los acuiferos y los parámetros hidrogeológicos. Asi mismo, la interpretación genética de los sedimentos y la caracterización de las discontinuidades que los limitan permiten realizar una extrapolación predictiva de las caracteristicas geológicas de subsuelo que pueden ser aplicadas a la modelización de las unidades hidrogeológicas

    Perceptions of risk to COVID-19 among young people from indigenous and rural communities in Southeast Mexico

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    Introducción. El 30 de enero de 2020, la OMS declaró emergencia sanitaria por la aparición de un nuevo coronavirus: SARS-CoV-2, que provoca la enfermedad COVID-19. En las primeras fases de una pandemia, adoptar conductas de precaución es crucial para prevenir una rápida propagación de la enfermedad. Objetivo. Analizar las percepciones de riesgo, emociones y comportamientos de jóvenes estudiantes residentes de regiones rurales e indígenas de gran marginación de Chiapas, México, sobre el COVID-19. Metódos. Se aplicó una encuesta a jóvenes estudiantes del Colegio de Bachilleres de Chiapas, ubicados en 17 municipios indígenas y rurales de alta y muy alta marginación. Resultados. 971 jóvenes respondieron la encuesta; 47.6% fueron hablantes de alguna lengua indígena. 92.2% señaló conocer o haber escuchado sobre COVID-19, el 88.4% cree en su existencia y el 76.4% señaló sentirse amenazado o muy amenazado. El 39.2% cree que el virus fue creado en un laboratorio y el 26.9% opina que fue hecho por el gobierno. Conclusiones. Es necesario implementar estrategias de promoción y educación para la salud con enfoque intercultural que contribuya a contrarrestar la desinformación y generar confianza en las autoridades y la respuesta sanitaria para hacer frente a la pandemia.ABSTRACT Introduction. On January 30, 2020, the WHO declared a health emergency due to the appearance of a new coronavirus: SARS-CoV-2, which causes the COVID-19 disease. In the early stages of a pandemic, adopting precautionary behavior is crucial to preventing the rapid spread of the disease. Objective. Analyze the perceptions of risk, emotions and behaviors of young students residing in rural and indigenous regions of great marginalization of Chiapas, Mexico, on COVID-19. Methods. A survey was applied to young students of the Colegio de Bachilleres de Chiapas, located in 17 indigenous and rural municipalities with high and very high marginalization. Results. 971 young people answered the survey; 47.6% were speakers of an indigenous language. 92.2% indicated knowing or having heard about COVID-19, 88.4% believe in its existence and 76.4% indicated feeling threatened or very threatened. 39.2% believe that the virus was created in a laboratory and 26.9% believe that it was made by the government. Conclusions. It is necessary to implement health promotion and education strategies with an intercultural approach that helps to counteract misinformation and build trust in the authorities and the health response to face the pandemic
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