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Measuring the Right Data—Verifying Experimental Boundary Conditions
Published in Josua P. Meyer, Michel De Paepe, The Art of Measuring in the Thermal Sciences, 2020
Due to the long length of the pipeline, a fiber optic cable (distributed temperature sensing—DTS) was applied to measure the local temperatures inside the pipeline. This was supplemented by six internal thermocouple measurements. The DTS system provided a high resolution with data points every 0.5 m inside the pipe; however, each value corresponds to an averaged value over a length of 0.5 m, so at sharp temperature transitions, these data can be deceptive. Installing fiber optic cables in such setups is a delicate matter when splicing is required to connect the optical connectors and establish interfaces/repair fiber breaks. Careful calibration of the optical circuit and avoiding local losses is key to ensure data quality. When selecting novel techniques based on optical sensors, it is advised to double up on the instrumentation in case of failures and to verify data independently. Furthermore, by having access locally to the fiber, a verification can be done through adding heat and measuring the response.
Structural monitoring of concrete, steel, and composite bridges in Poland with distributed fibre optic sensors
Published in Structure and Infrastructure Engineering, 2023
Tomasz Howiacki, Rafał Sieńko, Łukasz Bednarski, Katarzyna Zuziak
Standard monolithic sensors are manufactured with two optical fibres inside the composite core. Usually, one of them is treated as a redundant, but sometimes two independent interrogators can be connected to the sensor simultaneously. The type of fibre can be changed during production to meet the specific requirements of the applied device. For example, one fibre can be single-mode for DSS (Distributed Strain Sensing), while the second is multi-mode for DTS (Distributed Temperature Sensing). In the view of the above, all the bridge examples discussed hereafter are based on DFOS measurements using acrylate single-mode fibres or monolithic sensors.