The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers. Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can se...The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers. Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress and strain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relation of thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to the increase in the material volume resistivity during crack generation or propagation and the decrease in the resistivity during crack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect in the cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage and temperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in the concrete structures.展开更多
森林无线传感器的供电问题严重制约着物联网技术在林业上的运用,一种解决思路是利用土壤与空气之间的温度差,根据塞贝克效应进行温差发电,供给传感器使用。试验利用加热电缆对土壤进行加热,使之与空气之间形成温度差,验证利用基于塞贝...森林无线传感器的供电问题严重制约着物联网技术在林业上的运用,一种解决思路是利用土壤与空气之间的温度差,根据塞贝克效应进行温差发电,供给传感器使用。试验利用加热电缆对土壤进行加热,使之与空气之间形成温度差,验证利用基于塞贝克效应的森林土壤温差发电给林业无线传感网络节点供电的可行性。结果表明:在与自然状态下森林中土壤-空气温差一致时,输出电功率可达3.5 m W。通过引入温差传递效率系数η和滞后系数φ提出了土壤-空气温差与输出功率之间的关系模型,利用该关系模型可根据实际温差计算输出功率,对在特殊环境下工作的低功率器件供电研究具有重要意义。展开更多
基金This work was supported by NSFC(No.59908007)a foundation for phosphor plan from the Science and Technology Committee of Shanghai Municipality(No.01QE14052)The financial support from the Foundation for the University Key Studies of Shanghai was also gratefully acknowledged.
文摘The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers. Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress and strain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relation of thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to the increase in the material volume resistivity during crack generation or propagation and the decrease in the resistivity during crack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect in the cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage and temperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in the concrete structures.
文摘森林无线传感器的供电问题严重制约着物联网技术在林业上的运用,一种解决思路是利用土壤与空气之间的温度差,根据塞贝克效应进行温差发电,供给传感器使用。试验利用加热电缆对土壤进行加热,使之与空气之间形成温度差,验证利用基于塞贝克效应的森林土壤温差发电给林业无线传感网络节点供电的可行性。结果表明:在与自然状态下森林中土壤-空气温差一致时,输出电功率可达3.5 m W。通过引入温差传递效率系数η和滞后系数φ提出了土壤-空气温差与输出功率之间的关系模型,利用该关系模型可根据实际温差计算输出功率,对在特殊环境下工作的低功率器件供电研究具有重要意义。
