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To solve the problem of low demodulation accuracy of conventional peak-to-peak algorithm for fiber-optic Fabry-Perot (FP) sensors due to failure of determining the interference order, a novel cavity length sequence matching demodulation algorithm based on a combined valley peak positioning is proposed. Firstly, a pair of a peak and its neighboring valley in the reflection spectrum is selected and positioned, and two groups of interference orders are supposed to generate two groups of cavity length sequences. Finally, these cavity lengths are compared to find the real interference order of the peak and valley for the extraction of the accurate cavity length. In order to verify the feasibility and performance of the proposed algorithm, simulations and experiments were carried out for fiber-optic FP sensors with cavity lengths in the range of 15–115 μm. A demodulation accuracy better than 8.8 nm was found. The proposed algorithm can achieve highly accurate cavity length demodulation of fiber-optic FP sensors. [ABSTRACT FROM AUTHOR]

To solve the problem of low demodulation accuracy of conventional peak-to-peak algorithm for fiber-optic Fabry-Perot (FP) sensors due to failure of determining the interference order, a novel cavity length sequence matching demodulation algorithm based on a combined valley peak positioning is proposed. Firstly, a pair of a peak and its neighboring valley in the reflection spectrum is selected and positioned, and two groups of interference orders are supposed to generate two groups of cavity length sequences. Finally, these cavity lengths are compared to find the real interference order of the peak and valley for the extraction of the accurate cavity length. In order to verify the feasibility and performance of the proposed algorithm, simulations and experiments were carried out for fiber-optic FP sensors with cavity lengths in the range of 15–115 μm. A demodulation accuracy better than 8.8 nm was found. The proposed algorithm can achieve highly accurate cavity length demodulation of fiber-optic FP sensors.

A zero-cross detection algorithm was proposed for the cavity-length interrogation of fiber-optic Fabry−Perot (FP) sensors. The method can avoid the inaccuracy of peak determination in the conventional peak-to-peak method for the cavity-length interrogation of fiber-optic FP sensors caused by the slow variation of the spectral power density in peak neighboring regions. Both simulations and experiments were carried out to investigate the feasibility and performance of the zero-cross detection algorithm. Fiber-optic FP sensors with cavity lengths in the range of 150−1000 μm were successfully interrogated with a maximum error of 0.083 μm.

In this research, a series of experiments on combustion of Huadian oil shale semi-coke and rice straw as well as their mixture were conducted at different heating rates (10, 20, 50 and 80 °C/min) under atmospheric pressure, using a Perkin Elmer thermogravimetric analyzer. Combustion characteristics were investigated at different proportions of materials (L1, L2, L3, L4 and L5) and at different heating rates. The results revealed that the point of ignition and burnout shifted to lower temperature with increasing rice straw proportion in the mixture. In the combustion process, the interaction between the mixture components mainly occurred in the temperature range of 400 to 600 °C. It was found that in this stage the reaction ofbimodal components of semi-coke and rice straw took place. Besides, using the Gaussian multi-peak fitting method it was established that the derivative mass loss (DTG) curves displayed an overlapping peak, which consisted of three sub-peaks corresponding to the components of the blend. Moreover, based on the three sub-peaks, kinetic parameters and feature values were found employing the peak-to-peak method. The results showed that the reaction order of various sub-peaks for samples L1, L2, L3 and L4 was 1.17 to 2.27. The activation energies of sub-peaks were determined to be 21.89-99.79 KJ/mol throughout the analysis of the combustion mechanism. It was concluded that the model can be applied to determining combustion characteristics. [ABSTRACT FROM AUTHOR]

The relative yield of 3γ to 2γ annihilation was measured for a positron emitter, Na, with the new scintillator detectors lanthanum chloride (LaCl:Ce) and lanthanum bromide (LaBr:Ce), which had been characterised for comparison with high-purity germanium (HPGe) and sodium iodide (NaI(Tl)) detectors. The information obtained from the ortho-positronium 3γ decay in positron emission tomography (PET) can be a measure of the oxygen content in biological tissues by determination of this relative yield. However, it requires high resolution spectroscopy and detection efficiency. Characterisation of the new generation of scintillator detectors determines whether they could replace conventional scintillators and semiconductors. A series of experiments was carried out with different samples in order to study the effect of ortho-positronium formation. The peak-to-peak and the peak-to-valley methods were compared in the measurement of the relative yield of 3γ to 2γ annihilation. [ABSTRACT FROM AUTHOR]

A zero-cross detection algorithm was proposed for the cavity-length interrogation of fiber-optic Fabry–Perot (FP) sensors. The method can avoid the inaccuracy of peak determination in the conventional peak-to-peak method for the cavity-length interrogation of fiber-optic FP sensors caused by the slow variation of the spectral power density in peak neighboring regions. Both simulations and experiments were carried out to investigate the feasibility and performance of the zero-cross detection algorithm. Fiber-optic FP sensors with cavity lengths in the range of 150–1000 μm were successfully interrogated with a maximum error of 0.083 μm. [ABSTRACT FROM AUTHOR]