Surface Flaw Detection with Ferromagnetic Resonance Probes

Eddy current methods of flaw detection have been in use for many years. Frequencies used in this type of flaw detector normally range from tens of kilohertz to a few megahertz. We report on recent progress using a resonant probe which operates in the gigahertz frequency range, and compare its performance with classical eddy current methods

Surface Flaw Detection with Ferromagnetic Resonance Probes

Ferromagnetic probes resonating at microwave frequencies have previously been shown to function as sensitive detectors of surface breaking flaws in metals. A swept frequency mode of operation was used, with the resonance line of the probe displayed on an oscilloscope and the presence of a flaw indicated by a shift of the resonance line. This type of presentation lacks good discrimination between lift-off and and flaw signals and also reduces the probe scanning speed because the entire resonance line must be swept at each measurement point on the test specimen. Our new system operates under cw conditions, with a network analyser type of display giving the probe input impedance in polar coordinates. This provides liftoff discrimination and also enhances sensitivity. Experimental curves and their theoretical interpretations will be presented, and a portable prototype instrument will be described

Surface Flaw Detection with Ferromagnetic Resonance Probes

Small ferromagnetic resonators have been shown to provide effective electromagnetic detectors for surface flaws in magnetic and nonmagnetic metals. As such a resonator is moved along \u27the surface of a test piece it experiences a frequency shift when it passes over a flaw. lwo detection mechanisms are present: (1) an eddy current effect (2) a perturbation of the dc magnetic bias field used to tune the resonator. Results are given for experiments performed on machined slots in aluminum, titanium and steel and on tightly closed fatigue cracks in titanium. Results are also presented for some measurements on titanium aircraft fasteners

Scheduling language and algorithm development study. Volume 3, phase 2: As-built specifications for the prototype language and module library

Detailed specifications of the prototype language and module library are presented. The user guide to the translator writing system is included

Measurement of Surface Crack Opening Displacements Using Microwave Frequency Eddy Currents

An electromagnetic NDE technique for measuring the crack opening displacement of surface fatigue cracks is described. A ferromagnetic resonance probe utilizing yttrium-iron-garnet was used to induce eddy currents in an aluminum plate. The crack opening disolacement of a semi-elliptical fatigue crack evaluated at the surface was measured optically at several values of bending stress on the specimen. A technique is presented which allows the crack depth to be calculated from the measured COD at a given stress. The relative phase and magnitude of input vs. output signal to and from the resonating YIG sphere was recorded during the interaction of the FMR probe eddy currents and the fatigue crack. A method is shown to extract quantitative information from these signals and to correlate this information with the crack opening displacement

Is Entrepreneurial Success Predictable? An Ex-Ante Analysis of the Character-Based Approach

This paper empirically analyzes whether the character-based approach, which focuses on the personality structure and the human capital of business founders, allows prediction of entrepreneurial success. A unique data set is used consisting of 414 persons whose personal characteristics were analyzed by different methods, namely an one-day assessment center (AC) and a standardized questionnaire, before they launched their business. Results are partly unexpected and weaker than previous ex-post findings: first, we found correlations between the AC data and the questionnaire in one subgroup only. Second, the predictive power of the AC data is slightly better than that of the questionnaire, but lower than expected in theory. Interestingly, for those subgroups where the AC data have low predictive power, the questionnaire does better. Third, when success is measured in terms of employees hired, the character-based approach is a poor predictor. Copyright 2008 The Authors.

Study of electron anti-neutrinos associated with gamma-ray bursts using KamLAND

We search for electron anti-neutrinos ($\overline{\nu}_e$) from long and short-duration gamma-ray bursts~(GRBs) using data taken by the KamLAND detector from August 2002 to June 2013. No statistically significant excess over the background level is found. We place the tightest upper limits on $\overline{\nu}_e$ fluence from GRBs below 7 MeV and place first constraints on the relation between $\overline{\nu}_e$ luminosity and effective temperature.Comment: 16 pages and 5 figure