1. Research Scientist, Smart Sensor and NDT Lab, Dept. of Civil and Materials Engineering, Univ. of Illinois at Chicago, Chicago, IL 60607.
2. Visiting Professor, Smart Sensor and NDT Lab, Dept. of Civil and Materials Engineering, Univ. of Illinois at Chicago, Chicago, IL 60607.
3. Professor and Head, Smart Sensor and NDT Lab, Dept. of Civil and Materials Engineering, Univ. of Illinois at Chicago, Chicago, IL 60607 (corresponding author).