ABSTRACT
A novel seven-core fiber (SCF)-based sensor capable of simultaneous measurement of temperature and strain was proposed and experimentally demonstrated. The sensor consists of a fiber Bragg grating (FBG) and a SCF-based Mach-Zehnder interferometer (MZI). The MZI is formed by splicing a short section of SCF between two single-mode fibers (SMFs), and in the meantime, two fiber tapers that act as light splitter and coupler are formed at both ends of the SCF by the fusion splicing method. In addition, the FBG with a central wavelength of 1547.98 nm is cascaded at the end of one fiber taper, and thus simultaneous measurement of temperature and strain can be realized. The experiment result shows that the SCF-based MZI is only sensitive to temperature and has the higher temperature sensitivity of 93.11 pm/°C, while the FBG is sensitive to temperature and strain with sensitivities of 11.46 pm/°C and 0.627pm/µÎµ, respectively. The corresponding temperature and strain resolutions of the sensor are 0.21°C and 27.95µÎµ, respectively. The proposed sensor has the advantages of simple fabrication and high repeatability and has potential applications in many fields such as engineering machinery and building structure health monitoring.
ABSTRACT
A simultaneous measurement system of temperature and strain is proposed and fabricated, which has advantages of low cost and easy structure. The system is formed by combining a long period fiber grating with a polarization-maintaining fiber Sagnac loop. The transmission spectrum of the fiber Sagnac interferometer is modulated by LPFG. The simultaneous measurement of temperature and strain can be realized. The experimental results show that the wavelength of the dip is varied with temperature changing and applied strain on polarization-maintaining fiber, and the intensity of the dip is changed with applied strain on LPFG. The temperature sensitivity of the system is 0.181 81 nm x degrees C(-1), the strain sensitivity of LPFG is 0. 005 283 dB x mu epsilon(-1), and the strain sensitivity of polarization-maintaining fiber Sagnac loop is 0.015 72 nm x mu epsilon(-1). The experimental system indicates that the proposal is feasible and has an application prospect.
ABSTRACT
Though the body of bryophyte is small, its species is abundant (about 23,000), being an important part of biodiversity. The previous studies were focused on its taxology, while its ecological functions in ecosystem were ignored. Bryophyte can adapt to various environments, distribute in many extreme surroundings, and has rebuilding ability to environments. It has a very strong ability of holding and absorbing water, especially the epiphytic bryophyte can intercept a great deal of rain, and its function in water circulation is very obvious. Bryophyte can absorb a lot of nutrient elements by body surface, but its function in nutrient cycling was usually ignored. In some extreme environments, bryophyte is the important primary producer. Sphagnum biomass is more enormous, and maybe, is the important C pool. Bryophyte can sensitively response to the air and heavy metal pollution, and is a kind of bio-indicators. In order to promote the further studies on bryophyte ecological function, the related research advances were reviewed in this paper.
