In the application of fire prevention, sensor is expected to alarm before occurrence fire. We propose and experimentally demonstrate a long-range Raman distributed fiber temperature (RDFTS) early warning model (TEWM) for detection prevention. The TWEM includes first-order second-order moving average method. And method suitable prediction based on trends with significant changes. RDFTS achieved spatial resolution 3.0 28.6 m sensing range 1.38 28.9 km, respectively. experiment, placed in...

We propose and experimental demonstrate a Dynamic Threshold Identification Method (DTIM) based on the Raman distributed fiber sensor (RDFS) system for detecting pipeline leak. The DTIM can detect position of leak according to temperature measured by RDFS. includes three steps, which are space segmentation detection, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\sigma $ </tex-math></inline-formula>...

The field of tunnel fire detection requires a Raman distributed temperature sensor (RDTS) with high-accuracy and visual localization. A novel demodulation method to improve the measurement accuracy RDTS systems is presented. This based on optical dynamic difference compensation algorithm, which can eliminate power fluctuation. In addition, localization technology presented by using longitudinal lining model (LLM) three-dimensional (3D) display, enhances engineering application in detection....

Optical fiber distributed acoustic sensing (DAS) based on phase sensitive optical time domain reflectometry (ϕ-OTDR) has a great demand in many application fields with large signals, such as railway safety monitoring, cable vibration detection, etc. However, due to the inherent limits of unwrapping algorithm, signal whose change exceeds π cannot be recovered correctly by DAS. In this work, differential-unwrapping-integral (DUI) algorithm is proposed and demonstrated replace traditional for...

Accurate intrusion recognition along the optical fiber is still an enormous challenge in distributed acoustic sensing (DAS) based security system. Especially complex environments, various unknown disturbs such as animal activities will lead to high false alarm rate of detection In this work, accurate and effective pattern using a dual-stage-recognition network proposed demonstrated for practical environments with mechanical movements. The consists pre-recognition stage shallow classification...

Abstract We have numerically and experimentally investigated the flow rate measurement of pipeline based on optical fiber. Employing large eddy simulation (LES) model, we quantitatively analyzed pressure fluctuation pipe wall caused by turbulent in pipeline. The results shown that standard deviation was quadratic with rate. verified theoretical model using a distributed fiber acoustic sensing (DAS) system range from 0.61 m/s to 2.42 m/s. experimental were consistent very well. Furthermore,...

Pipeline integrity management is of great significance for ensuring the safety life and property. Due to stable running, no pressure drops, hidden characteristics, identification localization microleakage remain a challenging task. To solve this problem, we propose pipeline Leakage Noise Standard Deviation (LNSD) method based on highly sensitive distributed acoustic sensing (DAS) system. As medium, backscattering enhanced optical fiber (BEOF) placed in screw-like shape form continuous...

The sensing performance is severely affected by the intensity fading in phase-sensitive optical time domain reflectometry ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula> -OTDR) based distributed acoustic (DAS) system. manifests a stochastic amplitude fluctuation scattering signal. To suppress noise, heterodyne -OTDR system assisted with dual lasers independent...

Nowadays, early defect detection plays a significant role for the railway safety warning. However, existing methods cannot satisfy requirements of real-time and high-precision detection. Here, high-precision, distributed on-line method detecting rail is proposed demonstrated. When train goes through defects, instantaneous elastic waves will be excited by wheel-rail interaction, which further propagate along tracks bidirectionally. Through mounting backscattering enhanced optical fiber on as...

Solar cells can operate at a lower efficiency after certain temperature, which is caused by negative thermal coefficient. Therefore, the temperature prediction of photovoltaic (PV) modules critical to accurately evaluate devices. We propose and experimentally demonstrate Fuzzy Temperature Difference Threshold Method (FTDTM) based on Raman Distributed Sensor (RDTS) system for detection PV module temperature. The FTDTM consists four steps, i.e., division universe, establishment fuzzy...

In Raman distributed temperature system, the key factor for performance improvement is noise suppression, which seriously affects sensing distance and accuracy. Therefore, we propose experimentally demonstrate dynamic difference algorithm wavelet transform modulus maximum (WTMM) to de-noising anti-Stokes signal. Experimental results show that can increase from 3 km 11.5 accuracy increases 1.58 °C at of 10.4 km.

We propose and experimentally demonstrate a novel auto-correction method for improving temperature stability in long-range Raman distributed fiber sensors. The proposed is based on multi-stage constant control dynamic gain calibration technology, which can suppress the unstable photoresponsivity noise of system. experimental results indicate that optimized from ±12.6°C to ±7.2°C at sensing distance 30 km multimode using this method.

A novel Rayleigh noise suppression method is proposed to improve temperature accuracy and resolution for Raman distributed fiber-optics sensors. The demodulation can eliminate measurement inaccuracy caused by noise. experimental results indicate that the optimized from 6.2°C 1.7°C at a sensing distance of 9.1 km using method, leads about 1.5°C improvement compared with tradition 10.0 km. provides robust reliable high performance long ranges.

Precise control and measurement of the flow are essential for pipeline safety monitoring economic accounting. Nowadays, relies on point schemes such as mechanical flowmeters, which invade can irreversibly damage fluid pressure, especially when multipoint measurements required. To overcome these problems, we have explored a novel technique in acoustic field properties turbulence reflected by distributed backscattering light field, from be measured via imaging. The information is recorded...

A pipeline microleakage localization method based on the negative pressure wave propagation path fitting is proposed and demonstrated. Experimental results indicate that location error 3.85 cm for as small 1.0 mm.

A long-distance DAS system based on multi-span bidirectional erbium-doped fiber amplifier was proposed. Assisted with high ER pulse from cascaded AOMs, 246km sensing distance realized using four-segment relays. © 2022 The Author(s)

In order to suppress the noise of coherent fiber distributed acoustic sensing (DAS) system, spatio-temporal joint oversampling-downsampling technique is proposed. The spatial oversampling used for artificially dense sampling, whose spacing far less than target resolution. Then downsampling performed by average multiple differential sub-vectors utilized reduce influence vectors, which could completely eliminate interfere fading without increasing any system complexity and introducing...

Tide observation is an important part of marine engineering survey. We propose and demonstrate a new-type on-line tide monitoring system based on fiber distributed acoustic sensing (DAS), whose field test has shown its great prospect.

An anti-interference network of CNN-BiGRU for pipeline corrosion recognition assisted with fiber optic DAS system is proposed. For the seven degrees in high-interference environment, proposed model trained on data from one pipeline, can achieve average accuracy 83.4% other pipelines.

Precise control and measurement of the sand particles in sand-water two-phase flows are essential for pipeline safety monitoring economic accounting. Nowadays, conveying systems relies on point schemes such as invasive electrical resistance probes, which invade can irreversibly damage fluid pressure, especially when multi-point measurements required. To solve this problem, we propose a dynamic peak-seeking (DPS) method based highly sensitive distributed acoustic sensing (DAS) system to...

Objective:To explore the relation between distortion products and frequency tuning charateristics in cochlear basilar membrane.Method:Time variances curves of membrane response were measured by laser interferometery situ guinea pig cochlea.Result:Response sensitivity sharpness decreased with product amplitude become most low flat when disappeared.Conclusion:Distortion cochlea are related hearing tuning. They indicator whether function enhancing sharpening is still at work.

We propose and demonstrate a non-intrusive pipeline flow monitoring system based on the DAS. To best of our knowledge, this is first time DAS has been used for gas monitoring.

A non-invasive online method for pipeline sand connection detection based on dynamic peak-seeking is proposed and demonstrated. The test results show that the can identify minimum concentration as low 0.02%.