A high performance distributed sensor system with multi-intrusions simultaneous detection capability based on phase sensitive OTDR (Φ−OTDR) has been proposed and demonstrated. To improve system performance, three aspects have been investigated. Firstly, a model of one−dimensional impulse response of backscattered light and a Monte Carlo method have been used to study how the laser line width affects the system performance. Theoretical and experimental results show that the performances of the system, especially the signal−noise−ratio (SNR), decrease with the broadening of laser linewidth. Secondly, a temperature−compensated fibre Bragg grating with a 3 dB linewidth of 0.05 nm and a wavelength stability of 0.1 pm has been applied as an optical filter for effective denoising. Thirdly, a novel interrogation method for multi−intrusions simultaneous detection is proposed and applied in data denoising and processing. Consequently, benefiting from the three−in−one improvement, a high performance Φ−OTDR has been realized and four simultaneous applied intrusions have been detected and located at the same time along a 14 km sensing fibre with a spatial resolution of 6 m and a high SNR of 16 dB. To the best of our knowledge, this is the most multifunctional Φ−OTDR up to now and it can be used for perimeter and/or pipeline intrusion real−time monitoring.

Self-biting disease occurs in most farmed fur animals in the world. The mechanism and rapid detection method of this disease has not been reported. We applied bulked sergeant analysis (BSA) in combination with RAPD method to analyze a molecular genetic marker linked with self-biting trait in mink group. The molecular marker was converted into SCAR and loop-mediated isothermal amplification (LAMP) marker for rapid detection of this disease. A single RAPD marker A10 amplified a specific band of 1000bp in self-biting minks. The sequences of the bands exhibited 73% similarity to the Canis Brucella. SCAR and LAMP marker were designed for the specific fragment of RAPD marker A10 and validated in 30 self-biting minks and 30 healthy minks. c2 test showed difference (p<0.05) with SCAR and significant difference (p<0.01) with LAMP in the detection rate between the two groups, but LAMP method was more accurate than SCAR method. This indicated that LAMP can be used as a positive marker to detect self-biting disease in minks.