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Optical Fiber Sensing Solutions
Published in Krzysztof Iniewski, Ginu Rajan, Krzysztof Iniewski, Optical Fiber Sensors, 2017
Yuliya Semenova, Gerald Farrell
A fiber-optic sensor converts a physical parameter to an optical output. The key part of every fiber-optic sensor is a transducer—device that converts one form of energy associated with the physical parameter into another form of energy. Depending on the transducer type, all fiber-optic sensors fall into two broad categories: extrinsic and intrinsic sensors (Figure 2.1). In the case of an extrinsic sensor, the optical fiber serves as a delivery mechanism to guide the optical signal to the sensing region outside the fiber, where it is modulated in response to the physical parameter of interest and then collected by the same (or different) optical fiber and guided to a detector for processing. In an intrinsic sensor, the optical fiber acts both as the means for transporting the optical signal to/from the sensing region and as the transducer.
Progress on Optical Fiber Sensor for the Measurement of Physical Parameters and Chemical Sensing
Published in Tarun Kumar Gangopadhyay, Pathik Kumbhakar, Mrinal Kanti Mandal, Photonics and Fiber Optics, 2019
Placed in historical context, a fiber optic sensor and its instrumentation are preferable to conventional (e.g., piezo-electric) devices because of their dielectric properties, electrical isolation, immunity to electromagnetic/radio-frequency interference, inherent safety, wide bandwidth and highly sensitive detection. Fiber optic sensors also allow remote monitoring in localized areas. Other than fabrication jobs of a fiber optic sensor, the two major constraints of the fiber optic sensor are still under research. The first is to devise a means of stable packaging and mounting the sensor to make it suitable for real time measurement. The second is to develop practical signal detection and processing schemes for particular applications.
Real-time monitoring of railroad track tension using a fiber Bragg grating-based strain sensor
Published in Instrumentation Science & Technology, 2018
While the light is traveling inside the fiber, some portion is reflected, and the rest is transmitted due to environmental factors. It is possible to measure the magnitude of environmental factors by the analysis of this scattered light. In general, Raman, Brillouin and Rayleigh scattering are used in fiber optic sensing systems. Another method is the use of a fiber Bragg grating. Basically, a fiber optic sensor operates by modulating one or a few characteristics of the reflected light wave, such as phase, polarization and frequency, and provides an opportunity to measure environmental factors, such as strain, temperature, and pressure, from many points.[78910]
Experimental study and energy analysis on microwave-assisted lignite drying
Published in Drying Technology, 2019
Longzhi Li, Xiaowei Jiang, Xiaomin Qin, Keshuo Yan, Jian Chen, Tai Feng, Fumao Wang, Zhanlong Song, Xiqiang Zhao
A schematic diagram of microwave-assisted drying system is shown in Figure 1. A domestic microwave oven was modified by designing temperature and weight measurement system as well as date-acquisition system. The modified microwave oven (WP700-21, Galanz, China) was operated at a frequency of 2.45 GHz and was able to launch at five power levels: 123W, 231W, 385W, 539 W, and 700W. The dimensions of this oven were 515 mm ×385 mm ×262 mm. A digital balance (Shimadzu Cooperation, ATY-224) was adopted to record the continuous changes of sample mass during the drying process, whose accuracy was up to 0.1 mg. A fiber-optic sensor was a sensor that used optical fiber either as the sensing element (“intrinsic sensors”) or as a means of relaying signals from a remote sensor to the electronics that process the signals (“extrinsic sensors”). Fiber-optic sensors were immune to electromagnetic interference and did not conduct electricity so they could be used in places where there was high-voltage electricity. Fiber-optic sensors could be designed to withstand high temperatures as well. As a result, fiber-optic sensors (TPT-62) that had a measuring interval of –40–225 °C were used to obtain in-situ temperature information from the sample in a microwave field. Preliminary tests showed that the drying of lignite could be ignored at 123 W. This was an indicator that the drying process was hardly to be initiated at this power and it was because heat energy converted by microwave at this power level was not sufficient for water removal. Consequently, the drying process was mainly operated at 231 W, 385 W, 539 W, and 700 W in the current study. In the operation, a specified mass of lignite was placed in a quartz drier, which had a diameter of 50 mm and a height of 80 mm. Microwave penetrated the drier and was absorbed by the sample. The microwave oven was suspended from the balance through a fine thread. Consequently, the fine thread was inert to microwave, and the influence on the sample weight measurement might be negligible and can be ignored. Nitrogen with a flow of 100 mL/min was continuously imported into the drier during the drying process, which could avoid an undesirable spontaneous combustion. Normally, lignite pyrolysis was emerged followed by the drying process. As a result, the duration of drying process in this work was strictly controlled, corresponding to different microwave power level. The detailed duration of drying process was determined through preliminary tests. In each run, the changes of lignite weight occurred in each interval of 30 s were recorded by the date-acquisition system, unless it was specified.