We propose a simple and flexible multiwavelength Raman-fiber-laser-based long-distance remote-sensing scheme for simultaneous measurement of strain and temperature by use of fiber Bragg gratings. By combining two uniform fiber Bragg gratings with a tunable chirped fiber grating, we readily achieve simultaneous two-channel sensing probes with a high extinction ratio of more than approximately 50 dB over a 50-km distance. When strain and temperature are applied, lasing wavelength separation and shift occur, respectively, since the two uniform fiber Bragg gratings have identical material composition and different cladding diameters. This allows simultaneous measurement of strain and temperature for long-distance sensing applications of more than 50 km.
We propose a simple and flexible multiwavelength Raman fiber laser based on phase-shifted fiber Bragg gratings (FBGs) and a tunable chirped FBG. Using a simple multiwavelength Raman laser configuration with a single phase-shifted FBG and a tunable chirped FBG, we readily achieved simultaneous two-channel sensing probes with a high extinction ratio of more than 50 dB over a 50-km distance. The multiwavelength output was stable and the peak fluctuation was less than 0.5 dB. The temperature and strain sensitivities are estimated to be 10.1 pm/degrees C and 7.5 pm/microstrain, respectively.
We demonstrate a practical and simple, all fiber Bragg grating (FBG) based Raman laser sensing probe for long-distance, remote temperature sensing application. Using multiple laser cavities based on FBG's and a tunable chirped FBG, we obtain the simultaneous multi-channel remote temperature sensing operation at a 50 km distance. The temperature sensitivity is measured to be 7.15 pm/ degrees C.
The pharmacokinetics of prunasin after oral administration of amygdalin or a decoction of peach seeds was determined and compared in rats. A C 18 column was used for separation at a column temperature of 25 o C. The mobile phase consisted of 20% aqueous acetonitrile, and the flow rate was 0.5 mL/min. After oral administration of a decoction of peach seeds, prunasin was absorbed rapidly, reaching a maximum plasma concentration (C max ) of 62.1 mg/L within 45 min. After oral administration of amygdalin, the absorption of prunasin was delayed. The C max of prunasin was 42.9 mg/L and was reached at 60 min. Values for the pharmacokinetic parameters of prunasin, including T max , C max , AUC, T 1/2 , CL/F, and V1/F, were significantly different for the oral administration of amygdalin compared with that of a decoction of peach seeds.
A photonic crystal fiber with two large air holes outside the holey cladding region is fabricated to induce an effective long periodic grating (LPG) in the core by an electric arc discharge. We believe that the two large air holes lead to the asymmetric perturbation in the core under the electric arc discharge, thereby introducing the coupling to the first higher-order mode. The transmission characteristics of the PCF with the LPG for the external perturbation such as strain, curvature, and temperature are also investigated. It was found that the shift of resonance peak in the transmission spectrum depends on the bending direction. The curvature of 8.55 m -1 results in the center wavelength shifts of 1.8, 4.3, and 11 nm for a vertical, diagonal, and horizontal direction of the curvature to the large air-hole alignment, respectively.
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