In an inverse scattering problem, the fields in the inhomogeneous wave equation are known, and it is desired to solve for the source term. N. N. Bojarski has recently derived an Exact Inverse Scattering Theory for such "inverse source" problems. The problem of determining the generalized refractive index (i.e., the complex permeability and dielectric constant for an electromagnetic problem, or ...

Rapid inspection of aircraft structures for flaws is of vital importance to the commercial and defense aircraft industry. In particular, inspecting thin aluminum structures for flaws is the focus of a large scale R&D effort in the nondestructive evaluation (NDE) community. Traditional eddy current methods used today are effective, but require long inspection times. New electromagnetic technique...

The problem of scattering of an obliquely incident plane acoustic wave from an infinite solid elastic clad rod is formulated. Numerical calculations show the effects of the variations of the cladding thickness on both the backscattered pressure spectrum and individual normal modes. It is shown that various resonance frequencies have different levels of sensitivity to variations of the cladding ...

Bridge deck inspection is essential task to monitor the health of the bridges. This paper reports the data collection and analysis for bridge decks based on our novel robotic system which can autonomously and accurately navigate on the bridge. The developed robotic system can lessen the cost and time of the bridge deck data collection and risks of human inspections. The advanced software is dev...

We present an overview of recent superconducting quantum interference device (SQUID) research and development in Europe. History, theory and fundamental experiments and especially practical SQUIDs and SQUID readout were covered by Part I of this overview. Today, the SQUID itself is a rather mature device, the most sensitive magnetic flux and field detector, which finds use also as an amplifier....

The present work manifests the results of the dynamic Young's modulus, E, after cold compaction and after sintering of partially dense copper and silver compacts. For both metals, the results show that E in the porous compacts depends not only on the attained density, but also on the samples' consolidation route. For porous metals, it is demonstrated that the normalized longitudinal sound wave ...

Ultrasonic imaging is a powerful nondestructive evaluation (NDE) tool for flaw characterization. This thesis discusses the signal processing techniques developed for ultrasonic imaging of flaws in composite laminates. Commonly used time-domain signal processing techniques have problems including poor resolution, dependence on operator's experiences and subjectivity. Some transform-domain proces...

Laser acoustic emission (AE) method is a unique in-situ and non-contact nondestructive evaluation (NDE) method. It has a capability to detect signals generated from crack generation and propagation, friction and other physical phenomena in materials even in high temperature environment. However, laser AE system has lower signal-to-noise ratio compared to the conventional AE system using PZT sen...

Recently, a novel approach was proposed which combines advantages of both pulse (PT) and modulated (MT) infrared thermography. In a nondestructive evaluation (NDE) perspective, the specimen is pulse-heated as in PT and the rnix offrequencies ofthe thermal waves launched into the specimen are unscrambled by perforrning the Fourier transform of the temperature time evolution over the field of vie...

The critical role played by adhesive bonds in lap joints is well known. A good knowledge of the mechanical properties of adhesive bonds in lap joints is a prerequisite to the design and reliable prediction of the performance of these bonded structures. Furthermore, the lap joint may be subject to high-temperature environments in service. Early detection of the degree of thermal degradation in a...