Papers by Keyword: Fiber Bragg Grating (FBG)

Abstract: Fiber Bragg sensors become research focus of sensing technology, and have been widely used in many applications. This paper proposed a novel Fiber Bragg Grating sensor analyzer based on FPGA (Field Programmable Gate Array) and DSP (Digital Signal Processor) platform, which converted external parameter changes into wavelength shift in fiber Bragg gratings. The system can measure real-time temperature, strain, pressure, displacement and others through key steps including data acquisition, clutter Filtering, signal peak detection, Gaussian curve fitting and weighted wavelength calculation to carry out wavelength demodulation. Moreover, it is able to achieve fault diagnosis and positioning of the fiber link. Experimental results show that the system has advantages of low power consumption, good linearity, strong robustness, high precision and resolution on wavelength demodulation. And the system is still stable and reliable after a long test under different conditions.

Abstract: The air cooler reduce the working temperature of the transformer, high temperature will reduce the transformers life, and even make insulation overheating, aging, then the transformer will be damaged. The air cooler which is forced oil circulation in transformer outdoor in substation has been monitored. The real-time monitoring of 24-hours indicates that the temperature changes in the range of 3°C. The ambient temperature is lower than the temperature of fan about 1°C. At the long-term of 479 days, the average daily temperature range of fan is 35.32°C, the maximum temperature is 50.25°C on August 18,2011, and the maximum temperature is 14.93°C on January 17, 2011. The daily average of ambient temperature range is 37.59°C, the maximum temperature is 51.16°C on August 17, 2011,and the minimum temperature is 13.57°C on January 17, 2011. The maximum difference between the temperature of fan and the ambient temperature is 12.48°C on September 15, 2011. According to the relevant standards and monitoring results, the maximum threshold of fan temperature is defined to 80°C, and the threshold of temperature rise is 20°C.

Abstract: A novel kind of solution concentration sensor is designed and fabricated based on fiber Bragg grating with the single mode-etched multimode-single mode fiber Bragg grating structure. Sensing characteristics of Bragg grating to solution concentration is investigated without considering the effects of temperature, sensing detection of four kinds of solution is experimentally realized with the wavelength differences between high modes and the fundamental mode, the higher order modes of the etched multimode fiber is more sensitive to the surrounding refractive index than the fundamental mode.

Abstract: In order to increase the multiplying density of Fiber Bragg Grating (FBG) sensors, a novel FBG Sensing System based on CDMA technology has been developed. Simulation experiment indicates the CDMA technology combine with optical fiber grating sensing system together successfully. Furthermore, the system can distinguishes the FBG and enhance the FBG network band utilization.

Abstract: In order to find a more accurate center wavelength detection fitting algorithm for fiber Bragg grating (FBG) reflection spectrum, Based on the theory of neural network, we designed different neural network to study and fit the spectral data which has been acquired from FBG.In this paper,we have studied BP,RBFand wavelet neural network structure,comparing the network training time and the result of fitting curves ,wavelet neural network is proved to be the best fitting algorithm.

Abstract: In this paper the fundamental characteristics of fiber Bragg grating was described. The important parameters such as the length of fiber gratinggrating periodwhich strongly affected the characteristics of fiber Bragg grating were analyzed.

Abstract: With the progress of fiber grating sensing technology, FBG gradually become high-performance vibration sensor and has been widely used in vibration detection. Vibration sensing signal demodulation is the key technology for fiber Bragg grating sensing system. This paper details several fiber grating vibration sensor demodulation techniques and gives experiment result.

Abstract: This paper describes the use of embedded Fiber Brag Grating (FBG) sensor in the honeycomb core carbon fiber sandwich panel in smart composite materials for the application of monitoring the structural integrity of an aircraft. A part of vertical stabilizer was selected and reproduced using carbon fiber honeycomb core sandwich panels. The sandwich panel was fabricated in accordance to the generic sandwich structure and aviation industry standards, including the materials and also the method of construction. Using a carbon fiber from Hexcel as the face-sheet, Nomex honeycomb as the core, the sandwich panel was cured using Hysol EA9330 resin according to a standard curing process in the aviation industry. In order to make the sandwich panel as smart materials, optical sensor which has fiber bragg grating arrays, FBG, were embedded between the carbon fiber plies during the lay-out process. Using an FBG data logger and Instron 8802 Universal Testing Machine, the panel was subjected to flexural load and the FBG sensor signals were read at the load interval of 0.2 kN. From the experiment the results were taken and data was plotted and it shows that the FBG signals responded well to the load applied. In the future, the specimen will be used for further experiment for measuring strains and establishing the existence of damage in the panel.

Abstract: To remove or reduce the cladding layer thickness of fiber Bragg grating, the refractive index changes in the surrounding environment will affect the fiber Bragg grating effective refractive index of the core, resulting in changes in the Bragg wavelength. Solution concentration changes will cause changes in refractive index of the solution. A new kind of solution concentration sensor is designed with the etched phase shifted fiber Bragg grating, and concentration sensing detection with four kinds of solutions is experimentally demonstrated. With resolution concentration increasing, the phase shifted label wavelength shifts to the red, and the sensor is more sensitive in the case of higher concentration.

Abstract: Galloping and ice shedding, two of significant dynamic damages to bundle conductors, are both typical three-degree-of-freedom vibrations, while few technique is studied on monitoring the torsion oscillation of the whole bundles and the sub-conductors. For the monitoring of the vertical, horizontal, and especially torsional oscillations, a novel type of spacer damper is developed, which can also detect the torsion motion of each sub-conductor, with consideration of the special configurations of bundle cables and integrated with fiber bragg grating sensors. Then, a distributed FBG network is introduced.