New Publications

Following a work presented in the conference OFS-24 by ICONE post-doctoral researcher Hugo Martins, from FOCUS, a paper has been published in Journal of Lightwave Technology. The work describes the application of pattern recognition strategies to the signals acquired by a phase-sensitive OTDR. The aim is to prevent accidents by detecting and classifying potentially hazardous machinery activities near pipelines in real time. The study is performed on data of machinery activity recorded on the field, showing promising results for implementation in real scenarios.

-J. Tejedor; H. Martins; D. Piote; J. Macias-Guarasa; J. Pastor-Graells; S. Martin-Lopez; P. Corredera; F. De Smet; W. Postvoll; M. Gonzalez-Herraez, “Towards Prevention of Pipeline Integrity Threats using a Smart Fiber Optic Surveillance System,” J Lightwave Technol, vol.XX, no.XX, pp.XX-XX (2016) (pre-published); DOI:  10.1109/JLT.2016.2542981

 

Abstract: This paper presents the first available report in the literature of a system aimed at the detection and classification of threats in the vicinity of a long gas pipeline. The system is based on phase-sensitive optical time domain reflectometry (Φ-OTDR) technology for signal acquisition and pattern recognition strategies for threat identification. The system operates in two different modes: (1) machine+activity identification, which outputs the activity being carried out by a certain machine, and (2) threat detection, aimed at detecting threats no matter what the real activity being conducted is. Different strategies dealing with position selection and normalization methods are presented and evaluated using a rigorous experimental procedure on realistic field data. Experiments are conducted with 8 machine+activity pairs, which are further labeled as threat or non-threat for the second mode of the system. The results obtained are promising given the complexity of the task and open the path to future improvements towards fully-functional pipeline threat detection systems operating in real conditions.

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2016-06-07

Following a work which was accepted for the conference EWOFS 2016, a paper resulting from a collaboration between ICONE partner FOCUS and ICONE associated partner UAH, with participation of ICONE post-doctoral researcher Hugo Martins, has been accepted for publication in Photonics Technology Letters. It describes the possibility of extending the operation of traditional (single-frequency) ΦOTDR used for distributed vibration sensing, to the monitoring of distributed temperature gradients. The method only requires employing a low-cost post-processing algorithm to the standard ΦOTDR traces which are already acquired for the vibration detection, thus requiring a close to zero cost for implementation.

 

– A. Garcia-Ruiz, J. Pastor-Graells, H. F. Martins, S. Martin-Lopez and M. Gonzalez-Herraez, “Speckle analysis method for distributed detection of temperature gradients with ΦOTDR”, IEEE Photon Technol Lett, vol. xx, no. xx, pp. xxxxx-xxxxx (2016) (Pre-Published); DOI: 10.1109/LPT.2016.2578043

 

Abstract: A method to extend the operation of traditional single-frequency phase-sensitive optical time domain reflectometry (ΦOTDR) to the monitoring of distributed temperature gradients along an optical fiber is proposed and experimentally validated. The measurement principle is derived from the perturbation response of a single-wavelength ΦOTDR signal, which is analyzed as a unidimensional speckle pattern. The method could be implemented in parallel to standard ΦOTDR systems used for distributed vibration sensing with a close to zero cost and without affecting its operation, as it only requires a low computational cost post-processing of the traces which are already acquired. Frequency scanning of the laser, heterodyning or additional hardware are not required. The distributed detection of a temperature gradient of 2.5ºC over ten minutes is demonstrated.

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2016-06-07

Following a patent application which had been previously filled and a work which was accepted for the conference EWOFS 2016, a paper resulting from a collaboration between ICONE partner FOCUS and ICONE associated partner UAH, with participation of ICONE post-doctoral researcher Hugo Martins, has been accepted for publication in Optics Express. The work proposes a new type of operation for phase-sensitive OTDR based on the use of linearly chirped pulses and allows for distributed temperature/strain sensing using direct detection without requiring a frequency sweep. While traditional phase-sensitive OTDR used for temperature sensing requires measurement times of typically a few seconds/minutes, the proposed technique allows for temperature/strain sensing at kHz rates, thus allowing for dynamic sensing while maintaining the long term stability of the system.

 

– J. Pastor-Graells, H. F. Martins, A. Garcia-Ruiz, S. Martin-Lopez and M. Gonzalez-Herraez, “Single-shot distributed temperature and strain tracking using direct detection phase-sensitive OTDR with chirped pulses”, Opt. Express, vol. 24, no. 12, pp. 13121-13133 (2016)

 

Abstract: So far, the optical pulses used in phase-sensitive OTDR (ΦOTDR) were typically engineered so as to have a constant phase along the pulse. In this work, it is demonstrated that by acting on the phase profile of the optical pulses, it is possible to introduce important conceptual and practical changes to the traditional ΦOTDR operation, thus opening a door for new possibilities which are yet to be explored. Using a ΦOTDR with linearly chirped pulses and direct detection, the distributed measurement of temperature/strain changes from trace to trace, with mK/(4nε) resolution, is theoreticaly and experimentaly demonstrated. The measurand resolution and sensitivity can be tuned by acting on the pulse chirp profile. The technique does not require a frequency sweep, thus greatly decreasing the measurement time and complexity of the system, while maintaining the potential for metric spatial resolutions over tens of kilometers as in conventional ΦOTDR. The technique allows for measurements at kHz rates, while maintaining reliability over several hours.

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