Temperature sensitivity is greatly improved by taking the following three measures： proper long-period fiber grating （LPFG） whose strain coefficient of the core is larger than that of the cladding is employed, the ...Temperature sensitivity is greatly improved by taking the following three measures： proper long-period fiber grating （LPFG） whose strain coefficient of the core is larger than that of the cladding is employed, the LPFG is coated with a thin film of the material whose refractive index decreases with the temperature, and the sensor is encapsulated by metal material whose thermal expansion coefficient is large. By computer simulation, a measured temperature coefficient of 0.2375 nm/℃ and a temperature resolution less than 0.1 ℃ are obtained.展开更多
The influence of thermal stress on the temperature sensitivity of fiber Bragg grating-glass fiber reinforce polymer(FBG-GFRP) bars is studied by three methods,namely,direct experimental calibration method,stress analy...The influence of thermal stress on the temperature sensitivity of fiber Bragg grating-glass fiber reinforce polymer(FBG-GFRP) bars is studied by three methods,namely,direct experimental calibration method,stress analysis(finite element analysis) method and the method of apparent temperature sensitivity coefficient.In comparison with the other two methods,fewer parameters are required and the calculation is simple in the method of apparent temperature sensitivity coefficient,while the analytical error is limited within 2%.It is concluded that the results of the method of apparent temperature sensitivity coefficient could be good reference for engineering applications.展开更多
文摘为制备具有良好稳定性与灵敏度的温敏纳米纤维,将异丙基丙烯酰胺(N-isopropylacrylamide,NIPAm)与羟甲基丙烯酰胺(N-methylol acrylamide,NMA)通过自由基共聚合方法合成了聚异丙基丙烯酰胺-羟甲基丙烯酰胺共聚物P(NIPAm-co-NMA).并利用NMA的自交联能力和热处理,提高了共聚物P(NIPAmco-NMA)的交联度和低临界溶解温度区间的抗溶解能力.采用静电纺丝方法将共聚物P(NIPAm-co-NMA)制备成纳米纤维,研究了纺丝工艺条件对纤维形貌与直径的影响,以及热处理温度与时间对纳米纤维交联程度与形貌保持能量的影响.结果表明,共聚物P(NIPAm-co-NMA)的最佳纺丝参数为:聚合物质量分数为10%,纺丝电压为10 k V.共聚物P(NIPAm-co-NMA)纤维的最佳热交联温度为130℃,热处理时间为6 h,所获得纤维的交联度为82%,热交联后纤维可在低温水溶液中保持稳定,循环加热-冷却5次后其质量仍可保持原来的98%.
基金the Innovation Project of Guangxi Graduate Education Foundation (No.2007106020809M70).
文摘Temperature sensitivity is greatly improved by taking the following three measures： proper long-period fiber grating （LPFG） whose strain coefficient of the core is larger than that of the cladding is employed, the LPFG is coated with a thin film of the material whose refractive index decreases with the temperature, and the sensor is encapsulated by metal material whose thermal expansion coefficient is large. By computer simulation, a measured temperature coefficient of 0.2375 nm/℃ and a temperature resolution less than 0.1 ℃ are obtained.
基金supported by the National Natural Science Foundation of China (No.10902073)the Science Foundation of Construction Ministry(No.2010-K2-21) the Shenyang City Science Foundation of China (No.1081271-9-00)
文摘The influence of thermal stress on the temperature sensitivity of fiber Bragg grating-glass fiber reinforce polymer(FBG-GFRP) bars is studied by three methods,namely,direct experimental calibration method,stress analysis(finite element analysis) method and the method of apparent temperature sensitivity coefficient.In comparison with the other two methods,fewer parameters are required and the calculation is simple in the method of apparent temperature sensitivity coefficient,while the analytical error is limited within 2%.It is concluded that the results of the method of apparent temperature sensitivity coefficient could be good reference for engineering applications.
