Bioinspired algorithms for optimizing the harmonics contents of a PWM power inverter

Este trabajo se centra en la evaluación de diferentes técnicas de algoritmos bio-inspirados, que permitan reducir la distorsión armónica (THD) de la modulación de ancho de pulso (PWM) en inversores de potencia. Se realizó un amplio estudio que identifica y desarrolla algoritmos de optimización de inspiración biológica basados principalmente en la búsqueda tabú, algoritmos genéticos, optimización por enjambre de partículas y colonia de hormigas. Los métodos de optimización bio-inspirados son usados principalmente para encontrar los mejores parámetros operacionales de un PWM aplicado a inversores de potencia. Los mejores resultados fueron obtenidos cuando la posición de pulso (Pp) se localiza cerca a la posición central (Pp=0.5) o a la simetría del pulso. Dentro de los cuatro métodos estudiados el mejor resultado se encontró usando la técnica de optimización por colonia de hormigas, debido al valor de THD más bajo encontrado e igualmente con el 5 y 7 armónico con menos impulsos (Np= 38), casi 5 veces menor que el resultado usando la técnica optimización por enjambre de partículas, logrando reducir considerablemente las pérdidas bajando la frecuencia de conmutación (4560 Hz) de los dispositivos de potencia. Los algoritmos desarrollados pueden fácilmente adaptarse a cualquier problema de optimización, solo haciendo cambios en el número de variables y en la selección (o eliminación) de los criterios y así de esta manera obtener mejores resultados en problemas complejos.This paper deals with the evaluation of different bio-inspired algorithms techniques for reduction of harmonic distortion (THD) in pulse width modulation (PWM) of power inverters. A comprehensive study is performed, that identifies and develops biologically inspired optimization algorithms based mainly on tabu search, genetic algorithms (GA), particle swarm optimization (PSO), and ant colony optimization (ACO). These bio-inspired optimization methods were used to find the best operational parameters of a PWM applied to a power inverter. The best results were achieved when the pulse position is near to the middle position (Pp=0.5) or symmetry of the pulse. For the four methods analyzed he best result was obtained using ACO method based on the lowest THD content and less 5th and 7th harmonics magnitude with fewer pulses (Np=38), almost 5 times lower than the result of PSO (Np=179). It was achieved to reduce losses considerably with a reduction in the switching frequency of the power devices (4560 Hz). The algorithms developed can be easily adapted to any minimization problem, only making changes in the number of variables and selection (or elimination) criteria to obtain better results in complex problems

Exploring the potential of conventional and flash pyrolysis methods for the valorisation of grape seed and chestnut shell biomass from agri-food industry waste

Producción CientíficaResidual biomass is a valuable and growing by-product, but often underutilized. This research aims to investigate the possible strategies for the energetic valorisation of agri-food industry wastes: grape seed and chestnut shell. Pyrolysis thermal process was the selected for this work. Applied to biomass, pyrolysis is a promising method for the simultaneous production of biochar, bio-oil, and gas. Two different pyrolysis processes were conducted: conventional pyrolysis at 750 °C and flash pyrolysis at 750 °C and 850 °C. Flash pyrolysis yielded superior product properties compared to conventional pyrolysis. The gas obtained through flash pyrolysis presented a four-fold higher high heating value due to increased CH4 and H2 content. Bio-oil contains over 90% of polycyclic aromatic hydrocarbons, and calorific value reached up to 32 MJ kg−1 for grape seed, which is 7% more than bioethanol HHV. Biochar can be used both as fuel or as activated carbon precursor due to its high carbon content (91%). Calorific value of chestnut shell biochar (32.7 MJ kg−1), comparable to mineral coals, increased by 72% with respect to the value of this untreated raw material. This work approved the potential of flash pyrolysis as a method to process biomass wastes in a renewable energy scenario.FICYT - Fundación Fomento Asturias Investigación - FEDER (AYUD/2021/51379)Agencia Española de Investigación (PDC2022-133394-I00 y PID2021-124347OB-I00

Un estudio de caso: la rehabilitación de los edificios de viviendas del barrio de La Mina en Sant Adrià del Besòs (Barcelona). Análisis funcional y de las condiciones de seguridad, habitabilidad y mantenimiento

The La Mina district is a public housing development. Consisting of 2727 apartments which were built during the years 1968-74 at the height of the building sector boom, it is characterized by the mixture of building types and building methods employed and is remarkable for the use of the tunnel formwork technique. This paper presents and discusses the contents of the technical study which was prepared as a part of the Plan for Transformation and Improvement of the neighbourhood. The Plan provides for the rehabilitation of buildings and the urban reclassification and social regeneration of the neighbourhood, which is highly stigmatized as a problem area. The functional and structural safety conditions, the level of thermal and acoustic insulation, fire protection, accessibility and maintenance conditions were all analysed in detail in the technical study. In addition, several proposals were put forward for interventions aimed at reducing the most glaring deficiencies.El barrio de La Mina es un conjunto de 2.727 viviendas de promoción pública construido durante los años 1968-74, en pleno boom edificatorio del sector. Se caracteriza por la mezcla de tipos edificatorios y sistemas constructivos utilizados, destacando, por su relativa singularidad, la presencia de edificios en los que se aplicó la técnica de los denominados encofrados-túnel. El presente trabajo expone y comenta el contenido del estudio técnico elaborado a raíz de la confección del Plan Especial de Transformación y Mejora del barrio, que prevé la rehabilitación de los edificios y la recalificación urbanística y social del barrio, fuertemente estigmatizado por su elevada conflictividad. En dicho estudio se analizaron detalladamente los aspectos funcionales, las condiciones de seguridad estructural, el grado de aislamiento térmico, y las condiciones acústicas, de protección contra incendios, accesibilidad y mantenimiento de los edificios, elaborándose propuestas de intervención dirigidas a reducir las deficiencias más notables

Feasibility and Reliability of a Questionnaire to Assess the Mode, Frequency, Distance and Time of Commuting to and from School: The PACO Study

Active commuting to and from school has several health implications. Self-reporting is the most common assessment tool, but there is a high heterogeneity of questionnaires in the scientific literature. The purpose of this study was to analyse the feasibility and reliability of the Spanish “New Version of Mode and Frequency of Commuting To and From School” questionnaire in children and adolescents. A total of 635 children (5–12 years old) and 362 adolescents (12–18 years old) filled out the questionnaire twice (14 days apart). Feasibility was evaluated using an observational checklist. The test-retest reliability of the “New Version of Mode and Frequency of Commuting To and From School” questionnaire and the distance and time to school were examined using the kappa and weight kappa coefficient (κ). No misunderstanding of questions was reported. The time to complete the questionnaire was 15 ± 3.62 and 9 ± 2.26 min for children and adolescents, respectively. The questionnaire showed substantial and almost perfect kappa coefficients for the overall six items (k = 0.61–0.94) in children and adolescents. The “New Version of Mode and Frequency of Commuting To and From School” questionnaire is a feasible and reliable questionnaire in Spanish children and adolescents.Spanish Ministry of Economy, Industry and CompetitivenessEuropean Union (EU) DEP2016-75598-RUniversity of Granada, Plan Propio de Investigacion 2016, excellence actions: Units of ExcellenceUnit of Excellence on Exercise and Health (UCEES)Junta de AndaluciaConsejeria de Conocimiento, Investigacion y UniversidadesEuropean Union (EU) SOMM17/6107/UGREuropean Social Fund (ESF

Psychometric characteristics of a commuting-to-school behaviour questionnaire for families

The purposes of this study were: (a) to describe the patterns of modes of commuting to school (children) and to work (parents) separated by gender and age, (b) to validate the questions on children’s mode of commuting to and from school according to their parents, and (c) to analyse the reliability of a family questionnaire focused on commuting to school behaviours. A total of 611 parents (mean age: 43.28 ± 6.25 years old) from Granada (Spain) completed “Family commuting-to-school behaviour” questionnaire in two sessions separated by 14 days, (2016 and 2018). The validation between family and children’s questions was assessed using the Kappa and Spearman correlation coefficients, and the test–retest reliability within the family questions was assessed using the Kappa and the weighted Kappa. The children’s modes of commuting to school (mean age: 11.44 ± 2.77 years old) were mainly passive (57.7% to school) while parents’ modes of commuting to work were mainly active (71.6%). The validity of the mode of commuting was significant with high Kappa and Spearman coefficients. The test–retest reliability presented a good agreement for the mode of commuting to school in children, distance and time to school, and the mode of commuting to work in parents, while the questions on acceptable distance to walk or cycle to school showed a moderate to good agreement. The “Family commuting-to-school behaviour” questionnaire could be a useful tool to assess the mode of commuting of children, distance and time to school for researchers and practitioners

Using radio astronomical receivers for molecular spectroscopic characterization in astrochemical laboratory simulations: A proof of concept

We present a proof of concept on the coupling of radio astronomical receivers and spectrometers with chemical reactorsand the performances of the resulting setup for spectroscopy and chemical simulations in laboratory astrophysics. Several experiments including cold plasma generation and UV photochemistry were performed in a 40\,cm long gas cell placed in the beam path of the Aries 40\,m radio telescope receivers operating in the 41-49 GHz frequency range interfaced with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz resolution. The impedance matching of the cell windows has been studied using different materials. The choice of the material and its thickness was critical to obtain a sensitivity identical to that of standard radio astronomical observations. Spectroscopic signals arising from very low partial pressures of CH3OH, CH3CH2OH, HCOOH, OCS,CS, SO2 (<1E-03 mbar) were detected in a few seconds. Fast data acquisition was achieved allowing for kinetic measurements in fragmentation experiments using electron impact or UV irradiation. Time evolution of chemical reactions involving OCS, O2 and CS2 was also observed demonstrating that reactive species, such as CS, can be maintained with high abundance in the gas phase during these experiments.Comment: Accepted for publication in Astronomy and Astrophysics in September 21, 2017. 16 pages, 18 figure

Vortex deformation and breaking in superconductors: A microscopic description

Vortex breaking has been traditionally studied for nonuniform critical current densities, although it may also appear due to nonuniform pinning force distributions. In this article we study the case of a high-pinning/low-pinning/high-pinning layered structure. We have developed an elastic model for describing the deformation of a vortex in these systems in the presence of a uniform transport current density $J$ for any arbitrary orientation of the transport current and the magnetic field. If $J$ is above a certain critical value, $J_c$, the vortex breaks and a finite effective resistance appears. Our model can be applied to some experimental configurations where vortex breaking naturally exists. This is the case for YBa$_2$Cu$_3$O$_{7-x}$ (YBCO) low angle grain boundaries and films on vicinal substrates, where the breaking is experienced by Abrikosov-Josephson vortices (AJV) and Josephson string vortices (SV), respectively. With our model, we have experimentally extracted some intrinsic parameters of the AJV and SV, such as the line tension $\epsilon_l$ and compared it to existing predictions based on the vortex structure.Comment: 11 figures in 13 files; minor changes after printing proof

SrMnO3 thermochromic behavior governed by size-dependent structural distortions

The influence of particle size in both the structure and thermochromic behavior of 4H-SrMnO related perovskite is described. Microsized SrMnO suffers a structural transition from hexagonal (P6/mmc) to orthorhombic (C222) symmetry at temperature close to 340 K. The orthorhombic distortion is due to the tilting of the corner-sharing MnO units building the 4H structural type. When temperature decreases, the distortion becomes sharper reaching its maximal degree at ∼125 K. These structural changes promote the modification of the electronic structure of orthorhombic SrMnO phase originating the observed color change. nano-SrMnO adopts the ideal 4H hexagonal structure at room temperature, the orthorhombic distortion being only detected at temperature below 170 K. A decrease in the orthorhombic distortion degree, compared to that observed in the microsample, may be the reason why a color change is not observed at low temperature (77 K)