A Distributed Coaxial Cable Strainmeter for Earth Monitoring

1442623 Wei该基金支持分布式同轴电缆应变仪的开发和测试，该应变仪有可能提供高精度（~ ppm）和高时间分辨率（~1秒）的测量，并具有前所未有的高空间分辨率（~ 10米）。 该概念将依赖于已被赋予周期性电磁阻抗不连续性（布拉格光栅）的同轴电缆的测试，该周期性电磁阻抗不连续性允许电磁波的脉冲输入通过同轴波导或同轴电缆内的植入反射器的弱反射，这将使得能够实现基于法布里-珀罗干涉测量法的同轴应变计。 然后使用矢量网络分析仪分析透射和反射光谱。 PI还将探索新的信号放大技术，以减少沿电缆长度沿着具有多个传感器点的较长电缆长度沿着返回EM脉冲的损耗。 基于同轴电缆的应变计经受大变形（5%）和强横向碰撞/冲击的潜力可以在基于光纤的应变技术可能失效的某些极端条件下（例如，滑坡、冰下变形、钢结构变形）。 开发将聘请一名研究生协助：1）开发新的建模方法，用于设备设计和优化，2）探索混合软件-硬件信号处理技术; 3）建立一个便携式原型同轴应变仪; 4）表征原型？在实验室和现场的表现 *

1442623WeiThis grant supports development and testing of a distributed coaxial cable strainmeter that has the potential to offer high accuracy (~ ppm) and high temporal resolution (~1 sec) measurements with unprecedented high spatial (~ 10 m) resolution over kilometers. The concept will rely on tests of coaxial cables that have been imparted with periodic electromagnetic impedance discontinuities (a Bragg grating) which allow for weak reflections of a pulsed input of an electromagnetic wave through the coaxial waveguide or implanted reflectors within the coaxial cable that will enable a coaxial strainmeter based on Fabry-Perot interferometry. A vector network analyzer then is then used to analyze transmission and reflection spectra. The PI would also explore novel signal amplification techniques to reduce losses from returned EM pulses along longer lengths of cable with multiple sensors points along the length of the cable. The potential of the coaxial cable based strainmeter to survive large deformations (5%) and strong lateral collision/impact, may provide valuable and otherwise inaccessible information under certain extreme conditions where fiber optic based strain technologies may fail (e.g., landslides, subglacial deformation, steel structure deformation). The development will engage a graduate student to assist with: 1) development of new modelling methodology for device design and optimization, 2) explore hybrid software-hardware signal processing technology; and 3) build a portable prototype coaxial strainmeter; and 4) characterize the prototype?s performance in the laboratory and in the field.***