Strain and temperature measurement discrimination with forward Brillouin scattering in optical fibers

A novel method that enables simultaneous and discriminative measurement of strain and temperature using one single optical fiber is presented. The method is based on the properties of transverse acoustic mode resonances (TAMRs) of the optical fiber. In particular, it is based on the different sensitivity to temperature and strain that exhibit the radial modes R(0,m) and a family of torsional-radial modes denoted as TR(1)(2,m). We show that the resonance frequencies of both types of resonances shift linearly with temperature and strain, but at different rates. By the combined use of the different sensitivities of the two families of TAMRs, we experimentally demonstrate discriminative measurements of strain and temperature. A detection limit of strain and temperature better than 25 με and 0.2 °C is achieved

High accuracy measurement of Poisson's ratio of optical fibers and its temperature dependence using forward-stimulated Brillouin scattering

Transverse acoustic mode resonances enable a high accuracy determination of Poisson's ratio and elastic properties of optical fibers. An all-optical pump and probe technique is used for efficient excitation and accurate characterization of both, radial and torsional-radial acoustic resonances of optical fibers. Simple and precise algebraic expressions for the frequencies of high order acoustic resonances are derived, enabling a rigorous analysis of the experimental data using standard least squares fitting. Following this approach, the determination of Poisson's ratio does not require the measurement of any physical length, but only frequency measurements are required. An accuracy better than 1 is achieved. The dependence of the fiber Poisson's ratio with temperature is also determined experimentally

Recent advances in Forward Brillouin Scattering: Sensor applications

In-fiber opto-mechanics based on forward Brillouin scattering has received increasing attention because it enables sensing the surrounding of the optical fiber. Optical fiber transverse acoustic resonances are sensitive to both the inner properties of the optical fiber and the external medium. A particularly efficient pump and probe technique¿assisted by a fiber grating¿can be exploited for the development of point sensors of only a few centimeters in length. When measuring the acoustic resonances, this technique provides the narrowest reported linewidths and a signal-tonoise ratio better than 40 dB. The longitudinal and transverse acoustic velocities¿normalized with the fiber radius¿can be determined with a relative error lower than 10−4, exploiting the derivation of accurate asymptotic expressions for the resonant frequencies. Using this technique, the Poisson's ratio of an optical fiber and its temperature dependence have been measured, reducing the relative error by a factor of 100 with respect to previously reported values. Using a single-point sensor, discriminative measurements of strain and temperature can be performed, achieving detection limits of ±25 με and ±0.2 °C. These results show the potential of this approach for the development of point sensors, which can be easily wavelength-multiplexed

Forward Brillouin Scattering Spectroscopy in Optical Fibers with Whispering-Gallery Modes

Opto-mechanical interactions in different photonic platforms as optical fibers and optical microresonators are raising great attention, and new exciting achievements have been reported in the last few years. Transverse acoustic mode resonances (TAMRs) in optical fibers -which can be excited optically via electrostriction and generate forward Brillouin scattering (FBS)- are being promoted as the physical mechanism for new fiber-sensing concepts. Here, the study reports a novel approach to detect and characterize opto-excited TAMRs of an optical fiber based on the interplay with optical surface wave resonances, i.e., optical whispering-gallery mode (WGM) resonances. TAMRs induce perturbations in the geometry and the dielectric permittivity of the fiber over the entire cross-section. It is shown that these perturbations couple the acoustic with the optical resonances and affect WGMs in a noticeable way. The study proposes and demonstrates the use of WGMs for probing opto-excited TAMRs in optical fibers. This probing technique provides the narrowest linewidths ever reported for the TAMRs and demonstrates an optimum efficiency for the detection of low-order TAMRs. The interplay between sensitivity, bandwidth, and Q factor of the WGM resonance is discussed

Low-repetition-rate all-polarization maintaining thulium-doped passively modelocked fiber laser

We have developed a passively mode-locked, all-polarization maintaining, low-repetition-rate thulium-doped fiber laser (PM TDFL) emitting at 1951 nm and pumped by an erbium-ytterbium-doped all-fiber laser at 1561 nm. The PM TDFL was developed with a 44.67 m long polarization-maintaining all-fiber resonator Fabry-Perot using a semiconductor saturable absorber mirror at one end and a highly reflective fiber Bragg grating at the other. In this way, transform-limited low-repetition-rate light pulses at 2.3 MHz were generated, with each light pulse having a temporal width of 81 ps, and a spectral width of 50 pm. We have also compared the performance of this laser with a shortened version of this cavity, 6.25 m long, emitting at 15.6 MHz

Modelo financiero para el control de la productividad del capital de trabajo en las empresas del sector calzado en Cúcuta, Norte de Santander

Introduction: Financial control becomes a determining factor for the correct operation of companies, many fail in the first years of work because they do not carry out analyzes that assess their behavior according to what was projected with what was executed. Productivity is a determining factor to efficiently measure the resources invested in the working capital of companies. Objective: This article aimed to design a financial model oriented to the development of good control practices in the productivity of working capital in the footwear sector of Cúcuta. The methodology used is descriptive since it allowed to answer the question about which are the relevant variables for the productivity of working capital, after correlating and generating simulations in the Risk Simulator, identifying the variables that generate the greatest financial impact on footwear companies. In addition, this article presents information from sources that expose applications of the variables necessary for the construction of the model. Results: The financial model as a tool for control, monitoring and decision making in companies in this sector, defines and appropriates relevant variables such as accounts receivable and payable, inventories and income, depending on the productivity of working capital and the creation of value in companies in the footwear sector in Cúcuta, Colombia. Conclusions: The monitoring of accounts receivable is important, because a high correlation coefficient (73%) of the CXC was calculated with respect to the result of the productivity of the working capital, this indicates that if a rapid turnover of the portfolio is not achieved , will affect productivity and liquidity, reducing the performance of organizations.Introducción: El control financiero se convierte en un factor determinante para la correcta operación de las empresas, muchas fracasan en los primeros años de trabajo debido a que no realizan análisis que valoren el comportamiento de las mismas de acuerdo a lo proyectado con lo ejecutado. La productividad es un factor determinante para medir eficientemente los recursos invertidos en el capital de trabajo de las empresas. Objetivo: Este artículo tuvo como objetivo diseñar un modelo financiero orientado al desarrollo de buenas prácticas de control en la productividad del capital de trabajo en el sector calzado de Cúcuta. La metodología utilizada es descriptiva ya que permitió responder el interrogante sobre cuáles son las variables relevantes para la productividad del capital de trabajo, después de correlacionar y generar simulaciones en el Risk Simulator, identificando las variables que generan mayor impacto financiero en las empresas de calzado. Además, en el artículo se presenta información de fuentes que exponen aplicaciones de las variables necesarias para la construcción del modelo. Resultados: El modelo financiero como herramienta para el control, seguimiento y toma de decisiones en las empresas de este sector, se define y apropia variables relevantes como las cuentas por cobrar y pagar, inventarios e ingresos, dependientes a la productividad del capital de trabajo y a la creación de valor en las empresas del sector calzado en Cúcuta, Colombia. Conclusiones: El seguimiento a las cuentas por cobrar es importante, porque se calculó un coeficiente de correlación alto (73%) de las CXC respecto al resultado de la productividad del capital de trabajo, esto indica que, si no se logra una rápida rotación de cartera, afectará la productividad y la liquidez, disminuyendo el rendimiento de las organizaciones

Photoluminescence Imaging and LBIC Characterization of Defects in mc-Si Solar Cells

Today's photovoltaic market is dominated by multicrystalline silicon (mc-Si) based solar cells with around 70% of worldwide production. In order to improve the quality of the Si material, a proper characterization of the electrical activity in mc-Si solar cells is essential. A full-wafer characterization technique such as photoluminescence imaging (PLi) provides a fast inspection of the wafer defects, though at the expense of the spatial resolution. On the other hand, a study of the defects at a microscopic scale can be achieved through the light-beam induced current technique. The combination of these macroscopic and microscopic resolution techniques allows a detailed study of the electrical activity of defects in mc-Si solar cells. In this work, upgraded metallurgical-grade Si solar cells are studied using these two techniques

Avaliação prognóstica da síndrome coronariana aguda em pacientes com síndrome metabólica

Introduction: metabolic syndrome increases the risk for cardiovascular disease and doubles mortality.Objective: to identify the prognostic factors of death due to acute coronary syndrome in patients with metabolic syndrome.Method: a cohort analytical observational study was conducted in 186 patients with acute coronary syndrome admitted between 01 February 2015 and 20 October 2018. Clinical and epidemiological variables were included; the strength of association between the qualitative variables and the risk of developing death due to acute coronary syndrome in the presence of metabolic syndrome with Odds Ratio with 95% confidence interval was evaluated. Multivariate analysis was performed using the Cox logistic regression model.Results: the prevalence of the metabolic syndrome was 45.7%, with a mean age of 60.6 years; Female sex and age group over 61 years doubled the risk in a non-significant way. Left ventricular hypertrophy, heart failure and atrial fibrillation increased the risk of the appearance of a statistically significant acute coronary syndrome in the presence of the metabolic syndrome, p, 000. Moderate to severe left ventricular dysfunction [OR 5.7 95% CI (1,115-5,961) p, 000], Killip-Kimball class ≥II [OR 7.9 IC 95% (3, 10-20, 15) p, 000] and infarction without ST elevation [OR 2.970 95% CI (1.174-7.518) p, 000], were significantly related to death.Conclusions: metabolic syndrome increases the risk of suffering acute coronary syndrome and death but it is not significantly related to survival. Introducción: el síndrome metabólico incrementa el riesgo para enfermedad cardiovascular y duplica la mortalidad.Objetivo: identificar los factores pronósticos de muerte por síndrome coronario agudo  en pacientes con síndrome metabólico.Método: se realizó estudio observacional analítico de cohorte en 186 pacientes con síndrome coronario agudo admitidos entre 01 febrero de 2015 y 20 de octubre de 2018. Se incluyeron variables clínicas y epidemiológicas; se evaluó la fuerza de asociación entre las variables cualitativas y el riesgo de desarrollar muerte por síndrome coronario agudo en presencia de síndrome metabólico con el Odds Ratio con intervalo de confianza al 95%. Se realizó análisis multivariado utilizando el modelo de regresión logística de Cox.Resultados: la prevalencia del síndrome metabólico fue 45,7 %, con edad media de 60,6 años; sexo femenino y grupo de edades mayor de 61 años duplicaron el riesgo de forma no significativa. Hipertrofia ventricular izquierda, insuficiencia cardiaca y fibrilación auricular incrementaron el riesgo de aparición de síndrome coronario agudo estadísticamente significativa en presencia del síndrome metabólico, p, 000. Disfunción ventricular izquierda moderada a severa [OR 5.7 IC 95 % (1,115-5,961) p, 000], clase de Killip-Kimball ≥II [OR 7,9 IC 95 % (3,10-20,15) p, 000] e infarto sin elevación del ST [OR 2,970 IC 95 % (1,174-7,518) p, 000], se relacionaron significativamente con la muerte.Conclusiones: el síndrome metabólico incrementa el riesgo de sufrir síndrome coronario agudo y muerte pero no está relacionado significativamente con la supervivencia.Introdução: a síndrome metabólica aumenta o risco de doença cardiovascular e duplica a mortalidade.Objetivo: identificar os fatores prognósticos do óbito por síndrome coronariana aguda em pacientes com síndrome metabólica.Método: estudo de coorte observacional analítico foi realizado em 186 pacientes com síndrome coronariana aguda admitidos entre 01 de fevereiro de 2015 e 20 de Outubro de 2018. Foram incluídos variáveis clínicas e epidemiológicas; a força de associação entre variáveis qualitativas e o risco de morte por síndrome coronária aguda, na presença de síndrome metabólica com probabilidades confiança Rácio intervalo de 95% foi avaliada. A análise multivariada foi realizada usando o modelo de regressão logística de Cox.Resultados: a prevalência da síndrome metabólica foi de 45,7%, com idade média de 60,6 anos; Sexo feminino e faixa etária acima de 61 anos dobraram o risco de forma não significativa. hipertrofia do ventrículo esquerdo, falha cardíaca e fibrilação atrial aumentou o risco de síndroma coronária aguda estatisticamente significativa na presença de síndroma metabólico, p, 000. Disfunção Ventricular Esquerda moderada a grave [OU 5,7 (IC 95% 1,115-5,961) p.000], Killip-Kimball ≥II [OR 7,9, IC de 95% (3,10-20,15) p.000] e enfarte sem elevação do segmento ST [OR 95% CI 2,970 (1,174-7,518) p.000], estavam significativamente relacionados com a morte.Conclusões: A síndrome metabólica aumenta o risco de síndrome coronariana aguda e morte, mas não significativamente associada com a sobrevivência

Powering the future: a comprehensive review of battery energy storage systems

Global society is significantly speeding up the adoption of renewable energy sources and their integration into the current existing grid in order to counteract growing environmental problems, particularly the increased carbon dioxide emission of the last century. Renewable energy sources have a tremendous potential to reduce carbon dioxide emissions because they practically never produce any carbon dioxide or other pollutants. On the other hand, these energy sources are usually influenced by geographical location, weather, and other factors that are of stochastic nature. The battery energy storage system can be applied to store the energy produced by RESs and then utilized regularly and within limits as necessary to lessen the impact of the intermittent nature of renewable energy sources. The main purpose of the review paper is to present the current state of the art of battery energy storage systems and identify their advantages and disadvantages. At the same time, this helps researchers and engineers in the field to find out the most appropriate configuration for a particular application. This study offers a thorough analysis of the battery energy storage system with regard to battery chemistries, power electronics, and management approaches. This paper also offers a detailed analysis of battery energy storage system applications and investigates the shortcomings of the current best battery energy storage system architectures to pinpoint areas that require further study.This publication is part of the project TED2021-132864A-I00, funded by MCIN/ AEI/10.13039/501100011033 and by the European Union “NextGenerationEU”/PRTR”.Peer ReviewedPostprint (published version

Brúquidos (Coleoptera: Bruchidae) asociados a semillas de especies del género Mimosa L. (Leguminosae: Mimosoideae)

A checklist of bruchid species that feed seeds of Mimosa L. worldwide host plants is presented. A total number of 40 species are listed as well as its association with 65 species and 15 varieties of Mimosa genus. Moreover, nine new host associations for Bruchidae are recorded.Se presenta una lista de las especies de brúquidos que se alimentan de semillas de las especies del género Mimosa L. en el mundo. En total, se enlistan 40 especies de brúquidos asociados a 65 especies y a 15 variedades de Mimosa. Se dan a conocer nuevos hospederos para nueve especies de brúquidos