Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Damian HARASIM"

The optical measurement method for structural twist monitoring with using tilted Bragg grating sensor DOI:10.15199/48.2018.07.15

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From the beginning of their development, fiber Bragg gratings (FBGs) have been considered as excellent optical fiber sensing elements, suitable for measuring strain, temperature and force [1-3]. Advantages over the traditional electronic sensors such as low cost, immunity to electromagnetic interference and high multiplexing capability are the reason why FBG sensors recorded a rapid development in recent years. Extremely small size and lightweight makes them suitable for being embedded or attached into measured structure [4,5]. Typically in sensing applications there are traditional Bragg structures which are described as a periodic pattern of refractive index perturbations inscribed in core of single mode optical fiber. There are some possible modifications in such structures as chirp or tapering of fiber to obtain the desirable characteristics of manufactured grating [6]. Another technological modification which could be performed while inscribing process is introducing a tilting angle between fiber cross-section plane and refractive index pattern fringe in fiber core [7]. This change have a strong influence on spectral characteristics of created structure, especially in transmission spectrum. The most visible effect is appearance of series dips in the spectrum which is connected with enhancing of coupling light from the core mode to a large number of counter propagating cladding modes[8,9]. Tilted Bragg gratings (TFBGs) are most commonly used in fiber refractometry where the phenomenon of spectral dips disappearance with changes of sensor surrounding refractive index. Monitoring of structural health is an important request in many fields of engineering. One of the key parameters which are carrying information about the state of monitored structure is its twist. During the designing of optical fiber twist sensors, the most often used approach is to measure the change in circular birefringence induced by twist of polariz[...]

Accuracy improvement of Fiber Bragg Grating peak wavelength demodulation using wavelet transform and various center wavelength detection algorithms DOI:10.15199/48.2016.06.15

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The main feature of Fiber Bragg Gratings is that they perform a direct transformation of measured parameter into a shift in the center Bragg wavelength. This paper presents a possibility for extraction FBGs peak wavelength from spectra with high influence of noise by using wavelet transform. Spectra of tested FBG were measured in 20 points with different extending force applied to tested sample. Wavelet transform and various methods of center Bragg wavelength detection are jointly applied to improve wavelength detection accuracy. Experiment results shows that application of appropriate digital signal processing algorithms for denoising FBG spectra could greatly improve accuracy and linearity of fiber sensor processing characteristics. Streszczenie. Najważniejszą właściwością światłowodowych siatek Bragga (Fiber Bragg Gratings) jest liniowe przetwarzanie zmian mierzonej temperatury bądź odkształcenia na przesunięcie centralnej fali. Artykuł ten prezentuje możliwości wyznaczenia długości fali Bragga z widm silnie zaszumionych przy zastosowaniu transformaty Falkowej .Spectra rejestrowano w 20 punktach o różnych wartościach siły rozciągającej próbkę. Transformacja Falkowa oraz różne algorytmy wyszukiwania centralnej fali Bragga zostały zastosowane jednocześnie dla uzyskania poprawy precyzji wykreślania charakterystyki przetwarzania elementu mierzącego. Wyniki eksperymentu wskazują, że zastosowanie odpowiednich algorytmów cyfrowego przetwarzania sygnałów do widm FBG może w dużym stopniu poprawić dokładność wyznaczania charakterystyki przetwarzania światłowodowego czujnika. Poprawa dokładności demodulacji światłowodowych siatek Bragga dzięki użyciu transformaty falkowej i algorytmów detekcji centralnej długości fali Słowa kluczowe: Siatka Bragga, długość fali Bragga, transformata falkowa, czujnik naprężenia. Keywords: FBG, Bragg wavelength, wavelet transform, strain sensor. Introduction The main feature of fiber Bragg gratings is that they perf[...]

Development of energy-efficient vibration machines for the buiding-and-contruction industry DOI:10.15199/48.2019.04.10

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Vibration machines are used in processes for crushing, sorting, mixing, and compaction of construction materials, as well as in other processes that are characteristic for the building-and-construction industry. Vibration machines are designed, for the most part, for operation in the mode of over-resonance vibrations of the vibration machine actuator. In the design of such vibration machines, predominantly inertial forces are considered. Notwithstanding the fact that vibration machines are rated for steady-state operation, that is, for operation in conditions without transient processes, the energy efficiency of such vibration machines is low. Consequently, such vibration machines are characterized by that their reliability is reduced, materials consumption is high, and running time required for sufficient processing of materials is increased. Additionally, to the operation of vibration machines in the mode of normal harmonic vibrations of the vibration machine actuator, it is possible to operate vibration machines in modes of resonance[...]

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