Review of a Custom-Designed Optical Sensing System for Aero-Engine Applications

Fibre bundle-based reflective optical sensors are good candidates for parameter monitorisation in aero engines. Tip clearance is one of those parameters of great concern that is necessary to monitor. Within this optical technology, the evolution experienced by a custom-designed optical sensor is presented from its first configuration up to the fifth one. The performance of the last configuration is compared with those of other two optical sensors that are also based on a fibre bundle design. The comparison has been carried out in an experimental program in a transonic wind tunnel for aero engines. The proven high resolution and sensitivity of the last configuration of the optical sensor opens up the possibility to detect blade defects, cracks, etc. that could otherwise be hard to track.This work was supported in part by the European Regional Development Fund, in part by the Ministerio de Economía y Competitividad under project RTI2018-094669-B-C31, and in part by the Gobierno Vasco/Eusko Jaurlaritza under projects IT933-16, ELKARTEK (KK-2018/00078 and KK-2019/00051), EKINTZAILE 01560/2019 and HAZITEK (ZL-2020/00380). The work of J. Amorebieta is supported in part by a PhD fellowship from the University of the Basque Country (UPV/EHU), Vicerrectorado de Euskera y Formación Continua

Design, Fabrication and Testing of a High-Sensitive Fibre Sensor for Tip Clearance Measurements

A highly sensitive fibre bundle-based reflective optical sensor has been designed and fabricated for Tip Clearance measurements in a turbine rig. The sensor offers high spatial and temporal resolution. The sensor probe consists of a single-mode transmitting fibre and two concentric rings of receiving multimode fibres that collect reflected light in a differential detection gain configuration, yielding a highly linear calibration curve for distance measurements. The clearance measurement range is approximately 2 mm around the central point fixed at 3.2 mm from the probe tip, and the sensitivity of the probe is 61.73 mm(-1). The fibre bundle has been designed to ensure that the distance security specifications required for the experimental program of the turbine are met. The optical sensor has operated under demanding conditions set by the blade and casing design. The experimental results obtained so far are promising and lead us to think that the optical sensor has great potential for online clearance measurements with high precision.This work was funded in part by the Fondo Europeo de Desarrollo Regional (FEDER), in part by the Ministerio de Economia y Competitividad under project TEC2015-638263-C03-1-R, and in part by the Gobierno Vasco/Eusko Jaurlaritza IT933-16 and ELKARTEK (KK-2016/0030, KK-2017/00033, KK-2017/00089 and KK-2016/0059). The work of Josu Amorebieta is supported in part by a PhD fellowship from the Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), Vicerrectorado de Euskera y Formacion Continua

Simultaneous Sensing of Refractive Index and Temperature With Supermode Interference

[EN]In general, a sensor is used to monitor a single parameter only, and in many cases, a reference sensor is necessary to compensate the effect of temperature. Here, we demonstrate that a single supermode interferometer is capable of monitoring two parameters simultaneously. Said interferometer was fabricated with a segment of strongly coupled multicore fiber fusion spliced at the end of a standard single mode fiber. The free end of the multicore fiber was flat, thus, it behaved as a low reflectivity mirror whose reflection depended on the external refractive index. The reflection spectrum of our supermode interferometer consisted of well-defined periodic maxima and minima whose values and position varied when the interferometer was exposed to refractive index and temperature changes. In the Fourier domain, the changes of the interference pattern can be decoded easily. We demonstrate that the supermode interferometer here proposed can be useful to measure the thermo-optic coefficient of a sample. An important advantage of the device reported here is that the length of the multicore fiber is not determinant on the performance of the sensor. In addition, the device can be reused multiple times.This work was supported in part by the Ministerio de Economia y Competitividad (Spain) and the European Regional Development Fund under Grants PGC2018-101997-B-I00 and RTI2018-094669-B-C31, and in part by the Departamento de Educacion del GobiernoVasco, underGrant IT933-16

Highly Sensitive Multicore Fiber Accelerometer for Low Frequency Vibration Sensing

We report on a compact, highly sensitive all-fiber accelerometer suitable for low frequency and low amplitude vibration sensing. The sensing elements in the device are two short segments of strongly coupled asymmetric multicore fiber (MCF) fusion spliced at 180 degrees with respect to each other. Such segments of MCF are sandwiched between standard single mode fibers. The reflection spectrum of the device exhibits a narrow spectrum whose height and position in wavelength changes when it is subjected to vibrations. The interrogation of the accelerometer was carried out by a spectrometer and a photodetector to measure simultaneously wavelength shift and light power variations. The device was subjected to a wide range of vibration frequencies, from 1 mHz to 30 Hz, and accelerations from 0.76 mg to 29.64 mg, and performed linearly, with a sensitivity of 2.213 nW/mg. Therefore, we believe the accelerometer reported here may represent an alternative to existing electronic and optical accelerometers, especially for low frequency and amplitude vibrations, thanks to its compactness, simplicity, cost-effectiveness, implementation easiness and high sensitivity.Ministerio de Economia y Competitividad; Ministerio de Ciencia, Innovacion y Universidades; European Regional Development Fund (PGC2018-101997-B-I00 and RTI2018-094669-B-C31); Gobierno Vasco/Eusko Jaurlaritza (IT933-16); ELKARTEK KK-2019/00101 (mu 4Indust) and ELKARTEK KK-2019/00051 (SMARTRESNAK). The work of Angel Ortega-Gomez is funded by a PhD fellowship from the Spain Government. The work of Josu Amorebieta is funded by a PhD fellowship from the University of the Basque Country UPV/EHU

Sensitivity-optimized strongly coupled multicore fiber-based thermometer

[EN] In this paper, we report on a multicore fiber-based (MCF) temperature sensor that operates in a wide thermal range and that is robustly packaged to withstand harsh environments. To develop the sensor, the fundamentals concerning the effect of temperature on such fibers have been analyzed in detail to predict the most temperature sensitive MCF geometry. Thanks to it, the device, which operates in reflection mode and consists of a short segment of strongly coupled MCF fusion spliced to a standard single mode fiber, shows higher sensitivity than other devices with identical configuration. Regarding its packaging, it consists of an inner ceramic and two outer metallic tubes to provide rigidity and protection against impacts or dirt. The device was calibrated for a thermal range from -25 degrees C to 900 degrees C and a K-type thermocouple was used as reference. Our results suggest that the manufactured optical thermometer is as accurate as the electronic one, reaching a sensitivity up to 29.426 pm/degrees C with the advantage of being passive, compact and easy to fabricate and interrogate. Therefore, we believe this device is appealing for industrial applications that require highly sensitive temperature sensing in very demanding environments, and that the analysis included in this work could be analogously applied to develop sensitivity-optimized devices for other parameters of interest.Ministerio de Economia y Competitividad; Ministerio de Ciencia, Innovacion y Universidades; European Regional Development Fund (PGC2018-101997-B-I00 and RTI2018-094669-B-C31) ; Gobierno Vasco/Eusko Jaurlaritza (IT933-16) ; ELKARTEK KK-2019/00101 (mu 4Indust) and ELKARTEK KK-2019/00051 (SMARTRESNAK) . The work of Josu Amorebieta is funded by a PhD fellowship from the University of the Basque Country UPV/EHU. The work of Angel Ortega-Gomez is funded by a PhD fellowship from the MINECO (Ministerio de Economia y Empresa de Espana)

Compact Omnidirectional Multicore Fiber-Based Vector Bending Sensor

We propose and demonstrate a compact and simple vector bending sensor capable of distinguishing any direction and amplitude with high accuracy. The sensor consists of a short segment of asymmetric multicore fiber (MCF) fusion spliced to a standard single mode fiber. The reflection spectrum of such a structure shifts and shrinks in specific manners depending on the direction in which the MCF is bent. By monitoring simultaneously wavelength shift and light power variations, the amplitude and bend direction of the MCF can be unmistakably measured in any orientation, from 0 degrees to 360 degrees. The bending sensor proposed here is highly sensitive even for small bending angles (below 1 degrees).This work was funded in part by the Fondo Europeo de Desarrollo Regional (FEDER), in part by the Ministerio de Ciencia, Innovacion y Universidades-under projects RTC2019-007194-4, RTI2018-0944669-B-C31 and PGC2018-101997-B-and in part by the Gobierno Vasco/Eusko Jaurlaritza IT933-16, ELKARTEK KK-2019/00101 (mu 4Indust), and ELKARTEK KK-2019/00051 (SMARTRESNAK). The work of Josu Amorebieta is funded by a PhD fellowship from the University of the Basque Country UPV/EH

Packaged multi-core fiber interferometer for high temperature sensing

[EN]A small size and compactly packaged optical sensor for high-temperature measurements is reported. The sensor consists of a short piece of multi-core fiber (MCF) spliced to the distal end of a single-mode fiber. The packaging consists of an inner ceramic shield that prevents bending, curvature, and vibration effects on the MCF, and an outer metallic shield that protects the device against impacts. The interaction between specific supermodes excited in the MCF creates an interference pattern that shifts linearly with the temperature. The sensor was calibrated in the range from 200 to 1000 °C and a K-type thermocouple was used as a reference. The average temperature sensitivity was found to be 24.8 pm/°C with a response time of 15 s. Our results indicate that our MCF interferometric thermometer is as accurate as an electronic one with the advantage that it is passive. Therefore, we believe that the proposed sensor is suitable for industrial applications.This work was funded in part by the Fondo Europeo de Desarrollo Regional (FEDER), in part by the Ministerio de Economía y Competitividad under project TEC2015-638263-C03-1-R, and in part by the Gobierno Vasco/Eusko Jaurlaritza IT933-16 and ELKARTEK (KK/00033, KK-2017/00089 and KK-2018/00078). The work of Josu Amorebieta is supported in part by a PhD fellowship from the University of the Basque Country UPV/EHU, Vicerrectorado de Euskera y Formación Continua

Seroprevalencia de leishmaniosis visceral canina en la comuna 8 de Neiva y en cuatro municipios de Huila, Colombia

Introduction. Canine visceral leishmaniasis in endemic areas of Colombia could be a public health risk factor given the zoonotic nature of the disease. Ninety-six human cases of visceral leishmaniasis were reported in Colombia in 2004, 5 of them in Huila, where Lutzomyia longipalpis has been incriminated as the main vector species.Objective. To determine the prevalence of IgG antibodies against Leishmania chagasi in dogs from the sector 8 of the city of Neiva and the from the towns of Villavieja, Algeciras, Palermo and Rivera located in Huila, Colombia.Materials and methods. An epidemiological survey was carried out in 610 dogs, which included clinical examination and venopuncture for obtaining blood samples. Authorization was obtained from the dog owners. The sera were analyzed by the ELISA test with promastigotes of the L. chagasi strain MHOM/CO84/CL044B as antigen.Results. The canine population had an average age of 2.5 years; 67.3% of the dogs were males and the cross–bred animals were the most prevalent constituting 85% of those samples.On clinical examination the main signs were onicogriphosis 24.3%, lymphadenitis 10% and skin lesions 5%. The presence of antibodies was observed in 28.1% of the dogs from sector 8 of Neiva, 28% in Villavieja, 14.9% in Rivera, 10% in Palermo and 5.1% in Algeciras. An average ratio of five people cohabitating per seropositive dog was observed.Conclusions. The results reflect the exposure to Leishmania chagasi infection of dogs living in both urban and rural environments in the studied zones, and should encourage health authorities to carry out control measures to prevent the spread of this zoonotic disease.Introducción. La leishmaniosis visceral canina en áreas endémicas de Colombia se constituye en un factor de riesgo para la salud pública, dado el carácter zoonótico de la enfermedad. Durante el año 2004 se registraron 96 casos de leishmaniosis visceral humana en el país, de los cuales cinco correspondieron al departamento del Huila, zona de influencia del vector Lutzomyia longipalpis.Objetivo. Determinar la prevalencia de anticuerpos IgG contra Leishmania chagasi en sueros de caninos recolectados en los municipios de Rivera, Palermo, Villavieja, Algeciras y la comuna 8 de la ciudad de Neiva, Huila, Colombia.Materiales y métodos. Se realizó una encuesta epidemiológica a los propietarios de 610 caninos y previo consentimiento se llevó a cabo examen clínico general y recolección de muestra de sangre de cada una de las mascotas. Los sueros fueron analizados mediante el test de ELISA empleando como antígeno promastigotes de Leishmania chagasi, de la cepa MHOM/CO/84/CL044B. El análisis de datos empleó estadística descriptiva.Resultados. En la población canina 85% fueron mestizos, la edad promedio fue 2,5 años y 67,3% de los animales fueron machos. Al examen clínico las manifestaciones más frecuentes fueron: onicogrifosis 24,3%, linfadenitis 10% y lesiones cutáneas 5%. La frecuencia de anticuerpos IgG contra Leishmania chagasi en la comuna 8 de la ciudad de Neiva fue 28,1%, en Villavieja 28%, en Rivera 14,9%, en Palermo 10% y en Algeciras 5,1%. Adicionalmente, se observó un promedio de cinco personas convivientes por canino seropositivo.Conclusiones. Estos datos demuestran la exposición de los caninos que habitan los ambientes rurales y urbanos de las zonas en estudio a Leishmania chagasi y deben tenerse en cuenta para el fortalecimiento de los programas de control y prevención de esta zoonosis en el Sistema General de Seguridad Social en Salud

Los bosques termófilos de Canarias: Proyecto LIFE04/NAT/ES/000064

Los bosques termófilos, literalmente bosques amantes del calor, constituyen con diferencia el ecosistema zonal peor conservado y, por ello, menos conocido de los que integran la naturaleza canaria. Para profundizar en su conocimiento, el Cabildo Insular de Tenerife se puso en contacto con los autores de este libro, con el ánimo de solicitar un proyecto LIFE–Hábitat a la Unión Europea, referente a la restauración de una finca recién adquirida por dicha institución (finca de las Siete Fuentes, Teno) con bosque termófilo. Uno de los compromisos que se adquirieron en el proyecto LIFE fue la preparación de un libro acerca del bosque termófilo canario que permitiera divulgar los conocimientos adquiridos a lo largo del desarrollo del proyecto.Unión Europea, Excmo. Cabildo Insular de Tenerife, Universidad de La Laguna, en el marco del Proyecto LIFE Naturaleza “Restauración de los bosques de Juniperus spp. en Tenerife”

Prevalence of canine visceral leishmaniasis in municipalities of huila, colombia

With the purpose of establishing the prevalence of canine leishmaniasis a descriptive study was carried out in 17 villages of the municipalities of Neiva, Tello and Algeciras, in the department of Huila, Colombia. The selected canine population was composed of 307 dogs, which were submitted to clinical examination, stained smears of lymph node needle aspiration, and bleeding for serological analysis by the Immunofluorescent Antibody Tests (IFAT). The canine population was conformed by mestizo dogs, with a 3 year age average; 30,6 % were females. Upon physical examination loss of weight was observed in 31% of dogs; lynfadenopathy of the popliteal node in 3,2 %; alopecia in 21,8 %, eritematous lesions in 11,5 % and skin ulcers in 3,3 %. 17,2 % of the dogs has a positive serology and in 1.43% of them, amastigotes were observed in the smears of lymph node aspirates. These prevalence of anti-L. chagasi antibodies is relatively high compared with other studies in Colombia and in other countries. The present study, confirms the endemic nature of the illness in the area, high lighting the need for strengthening public health surveillance and active search for human cases.Con el propósito de establecer la prevalencia de leishmaniosis canina se efectuó un estudio descriptivo en 307 caninos, ubicados en 17 veredas de los municipios de Neiva, Tello y Algeciras, a los cuales se les practicó examen clínico, punción y aspiración del ganglio linfático poplíteo para extendido y coloración en lámina; toma de sangre completa por venopunción para análisis mediante la técnica de inmunofluorescencia indirecta. La población canina estuvo conformada por perros mestizos con edad promedio de tres años; el 30,6 % fueron hembras y el 69,4 % machos. En el examen físico de los caninos se observó: enflaquecimiento, 31 %; onicogrifosis, 29,3 %; linfadenitis de ganglio poplíteo 3,2 %; áreas alopécicas 21,8 %; lesiones eritematosas 11,5 % y úlceras cutáneas 3,3 %. El 1,4 % de los caninos analizados presentaron amastigotes en el aspirado y el 17,2 % fueron seropositivos. La prevalencia de anticuerpos contra L. chagasi es alta comparada con otros estudios realizados en Colombia y otros países, corroborando la endemicidad de la enfermedad en el área. Por consiguiente, es necesario fortalecer las estrategias de vigilancia epidemiológica y la búsqueda activa de casos humanos