TY - GEN A1 - Kowarik, Stefan A1 - Pithan, L. T1 - kowarik-labs/AI-reflectivity: v0.1 N2 - AI-reflectivity is a code based on artificial neural networks trained with simulated reflectivity data that quickly predicts film parameters from experimental X-ray reflectivity curves. This project has a common root with (ML-reflectivity)[https://github.com/schreiber-lab/ML-reflectivity] and evolved in parallel. Both are linked to the following publication: Fast Fitting of Reflectivity Data of Growing Thin Films Using Neural Networks A. Greco, V. Starostin, C. Karapanagiotis, A. Hinderhofer, A. Gerlach, L. Pithan, S. Liehr, F. Schreiber, S. Kowarik (2019). J. Appl. Cryst. For an online live demonstration using a pre-trained network have a look at github. KW - Artificial neural networks KW - X-ray reflectivity PY - 2019 DO - https://doi.org/10.5281/zenodo.3477583 PB - Zenodo CY - Geneva AN - OPUS4-51888 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hicke, Konstantin A1 - Chrusciscki, Sebastian A1 - Krebber, Katerina T1 - Real-time distributed temperature gradient sensing using amplitude-based C-OTDR and sensing fiber with inscribed scattering dots N2 - We present a technique for distributed temperature gradient sensing in real-time along an optical fiber utilizing simple amplitude-based direct-detection coherent optical time domain reflectometry (C-OTDR) and a special sensing fiber. Our technique enables us to determine phase changes or low-frequency variations of the C-OTDR signal stemming from temperature variations. The distinct feature of the used sensing fiber is its structuring with equidistant strongly scattering dots. Consecutive pairs of these scatterers form the dominant local interferometers, effectively overwriting the otherwise highly nonlinear transfer function of common optical fiber. This enables a quasi-phase-resolved evaluation of perturbation responses originating from temperature changes at sensor positions between the scatterers. Using our method, we show the measurement of a nonlinear temperature transient from a heating process with a maximum temperature gradient of 0.8 °C over 20 s and a total temperature increase of 28.4 °C. This method requires almost no post-processing and can be used for simultaneous distributed vibration sensing (DVS) and quantification of local temperature gradients in a single fiber, e.g., for the use in condition monitoring of infrastructure or industrial installations. T2 - Seventh European Workshop on Optical Fibre Sensors, 2019 CY - Limassol, Cyprus DA - 01.10.2019 KW - C-OTDR KW - DVS KW - Distributed temperature gradient sensing KW - Distributed vibration sensing KW - Fibre optic sensors KW - Power cable monitoring KW - Structured fiber PY - 2019 AN - OPUS4-50255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Marcus A1 - Munzke, Dorit A1 - Duffner, Eric A1 - Eisermann, René A1 - Schoppa, André A1 - Szczepaniak, Mariusz A1 - Strohhäcker, J. A1 - Mair, Georg T1 - Monitoring of type IV composite pressure vessels with multilayer fully integrated optical fibre based distributed strain sensing N2 - We present the results of distributed fibre optic strain sensing for condition monitoring of a hybrid type IV composite overwrapped pressure vessel using multilayer integrated optical fibres. During load cycle tests material fatigue could be localised and monitored 17000 load cycles before burst. T2 - TAHYA Workshop "Structural health monitoring" CY - Berlin, Germany DA - 27.11.2019 KW - Distributed fibre optic sensing KW - Hybrid composite pressure vessel KW - Structural health monitoring PY - 2019 AN - OPUS4-49996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stajanca, Pavol A1 - Krebber, Katerina T1 - Investigation of bare and tight buffered optical fibers towards distributed humidity sensing N2 - Humidity is one of principal environmental parameters that plays an important role in various application areas. Distributed humidity/water sensing is sought after in wide range of applications including concrete condition monitoring in civil engineering, SHM of large structures such as dykes or dams, soil moisture measurement in agriculture or leak detection in pipeline or sewage industry. Using humidity-induced strain of specialty hygroscopic coating materials, such as polyimide (PI) seems as the most promising approach so far. In this work, relative humidity and temperature response of different commercial PI-coated and tight-buffer fibers is investigated for the development of distributed humidity sensor. T2 - Abschlussmeeting des MONALISA-Projekts CY - Berlin, Germany DA - 06.12.2019 KW - Distribute fiberoptic sensor KW - Distributed humidity sensing PY - 2019 AN - OPUS4-49977 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stajanca, Pavol A1 - Hicke, Konstantin A1 - Kapa, Thomas A1 - Krebber, Katerina T1 - MONALISA-Teilprojekt: Adaption erforschter faseroptischer Messverfahren für die Entwicklung und Bereitstellung fehlender Sensortechnik für vordringliche Mess- und Monitoringaufgaben in künftigen Stromnetzen N2 - Das Teilprojekt zielt auf die Entwicklung integrierbarer verteilter faseroptischer Sensoren (u. a. verteilte Brillouin-Sensorik, verteilte akustische Sensorik) für die Langzeitüberwachung von Betriebsparametern in Hoch- und Mittelspannungskabelanlagen. Mit Hilfe der Sensoren sollen unzulässige Dehnungen, Übertemperaturen und das Eindringen von Feuchte, z. B. in Unterseekabeln, detektiert werden. Das Teilprojekt beinhaltet ebenfalls die Entwicklung integrierfähiger Sensoren für verteiltes (vibro-)akustisches Monitoring an Unterseekabeln, vor allem zur Lokalisierung und zur Abwendung von Störfällen und Schäden durch äußere mechanische Einflüsse (z. B. Ankerwurf). T2 - Abschlussmeeting des MONALISA-Projekts CY - Berlin, Germany DA - 06.12.2019 KW - Verteilte faseroptische Sensorik KW - Stromnetzen KW - Stromkabelüberwachung PY - 2019 AN - OPUS4-49976 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kowarik, Stefan A1 - Krebber, Katerina T1 - Neue Entwicklungen der Faseroptische Sensorik: von Infrastruktur-Monitoring zu neuronalen Netzen N2 - Der Vortrag gibt eine Einführung zu obigen Themen auf Niveau von Master Studierenden. T2 - TUM-Tag CY - BAM, Berlin, Adlershof DA - 19.06.2019 KW - Faseroptische Sensorik PY - 2019 AN - OPUS4-49902 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kowarik, Stefan A1 - Krebber, Katerina T1 - Smart materials and structures based on fiber optic sensing N2 - This talk gives an overview of basic techniques. Towards the end some applications of neural networks are discussed. T2 - BAM - IFW workshop CY - Berlin, Germany DA - 25.11.2019 KW - Artificial neural networks KW - Fiber optic sensing PY - 2019 AN - OPUS4-49901 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Schreier, Andy A1 - Krebber, Katerina T1 - Distributed BOFDA measurement on an 86 m long perfluorinated polymer optical fiber T2 - POF 2019 Proceedings N2 - We present our research on the development of a Brillouin optical frequency-domain analysis (BOFDA) using a perfluorinated graded-index polymer optical fiber (PFGI-POF) as a sensing fiber. The described works include investigations both on the selection of the setup components with respect to mode coupling effects and on the impact of the humidity cross-sensitivity. The suitability of the developed POF-based BOFDA is proved by a distributed measurement on an 86 m long PFGI-POF recorded with the spatial resolution of 6 m. T2 - 28th International Conference on Plastic Optical Fibers CY - Yokohama, Japan DA - 20.11.2019 KW - Brillouin sensing KW - BOFDA KW - Perfluorinated graded-index polymer optical fiber KW - PFGI-POF PY - 2019 SP - 27 EP - 28 AN - OPUS4-49865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha T1 - Real-time dynamic strain sensing in optical fibers using artificial neural networks N2 - The use of artificial neural networks (ANNs) is demonstrated for efficient real-time data processing in optical fiber sensing applications. Using ANN-based algorithms, two orders of magnitude improved computation time and improved measurement resolution is achieved for distributed strain sensing using the wavelength-scanning coherent optical time domain reflectometry technique. T2 - WORKSHOP - Machine learning in optical analytics CY - Berlin, Germany DA - 13.11.2019 KW - Artificial neural networks KW - Distributed acoustic sensing (DAS) KW - Distributed vibration sensing KW - Signal processing PY - 2019 AN - OPUS4-49869 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liehr, Sascha A1 - Breithaupt, Mathias A1 - Krebber, Katerina T1 - Distributed Humidity Sensing in PMMA Polymer Optical Fibers N2 - The distributed measurement of relative humidity is a sought-after capability for a wide range of applications in civil engineering and structural health monitoring. We show that polymethyl methacrylate (PMMA) optical fi-bers can be employed as a sensor medium to conduct distributed humidity measurement by analyzing Rayleigh backscattering traces obtained by OTDR. We make use of the effect that water penetrates the fiber core and directly influences the local fiber attenuation and Rayleigh backscatter coefficient. We conducted distributed backscattering analysis for two different pulse wavelengths: 500 nm and 650 nm. The 650 nm results are susceptible to both, attenuation changes and backscatter changes, whereas backscatter results at 500 nm are not affected by humidity-induced attenuation and only exhibit a change of Rayleigh backscattered power as a function of humidity. The combined measurement and analysis of both parameters at these two wavelengths has the advantage that cross-sensitivities on backscatter change and attenuation, such as strain and tempera-ture changes, could be separated from the humidity response of the fiber. We present laboratory results for a humidity range between 30% and 90% for both pulse wavelengths: including step responses, humidity cycles and hysteresis analysis. In addition to the attenuation and backscatter coefficient dependence, we also analyze optical runtime changes as a function of humidity. POFs have the advantage that they can be directly embed-ded into materials such as concrete or soil to measure water content or localize water ingress. Standard step-index PMMA POFs can be used as a distributed relative humidity sensor up to 200 m distance. T2 - The 28th International Conference on Plastic Optical Fibers CY - Yokohama, Japan DA - 20.11.2019 KW - Distributed humidity sensor KW - PMMA KW - Rayleigh scattering KW - Polymer optical fiber KW - Distributed sensor KW - Optical fiber sensor KW - OTDR PY - 2019 AN - OPUS4-49868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -