Recent research results indicate that eddy current conductivity measurements can be exploited for nondestructive evaluation of subsurface residual stresses in surface-treated nickel-base superalloy components. According to this approach, the depth-dependent electric conductivity profile is calculated from the measured frequency-dependent apparent eddy current conductivity spectrum. Then, the re...

This paper presents a generalized likelihood ratio technique for detection of defect locations from bobbin coil eddy current data. First a Neyman±Pearson (NP) decision rule for detection of known random signals (in presence of noise) is discussed. The result is then generalized to the problem of detection of unknown random signals that are commonly found in bobbin coil eddy current data. The pe...

Magnetic induction tomography (MIT) is a tomographic technique utilising inductive coils and eddy currents to map the passive electromagnetic properties of an object. Eddy current methods are widely used for non-destructive testing (NDT) in inspection of metallic structures. Eddy current based NDT uses a single coil or a pair of coils to scan the samples. As an emerging NDT technique, MIT scans...

Magnetic field inhomogeneities like eddy current-related gradient fields cause geometric distortions in echo-planar imaging (EPI). This in particular affects diffusion-weighted imaging where these distortions vary with the direction of the diffusion weighting and hamper the accurate determination of diffusion parameters. The double-spin-echo preparation often used aims to reduce the cumulative ...

Introduction Acquisition of a set Diffusion Weighted Images (DWIs) allows Diffusion Tensors and Tensor-derived quantities such as Fractional Anisotropy (FA) and Trace (TR) to be computed and used to infer the underlying white matter structure in the brain. DWIs are usually acquired with an echo-planar imaging (EPI) pulse sequence that produces images degraded by B0 field inhomogeneity, eddy cur...

We want to give a systematic presentation of voltage or current intensity excitation for time-harmonic eddy-current problems. The key point of our approach resides in a suitable power law, that permits to understand the role of voltage excitation. We also enlighten the influence of the boundary conditions on the proposed formulations.

The need for interaction between customer and supplier during the production of a service makes it difficult to measure and evaluate the soft factors of a service process. They cannot be measured by using objective measuring equipment. Soft factors rather have to be measured and evaluated by people who function as subjective measuring equipments. The use of Likert scales is the common way to me...

It is shown in this paper that, in contrast with most other materials, shot-peened nickel-base superalloys exhibit an apparent increase in eddy current conductivity at increasing inspection frequencies, which can be exploited for nondestructive residual stress assessment of subsurface residual stresses. It has been found that the primary reason why nickel-base superalloys, which are often used ...