Detecting Surface Cracks on Dates Using Color Imaging Technique

An Ultrasonic Technique for Sizing Surface Cracks

Rayleigh surface waves are proposed as a non-destructive method to find the depth of surface cracks. The paper describes how dynamic photoelasticity was used to develop an understanding of the subsurface interactions between R-waves and a narrow slot. A frequency analysis of the transmitted wave confirmed that the slot acts as a low pass filter for the high frequency Fourier components of the i...

Potential Drop Imaging Technique for Sensitive Nde of Small Surface Cracks

This paper reports the potential drop technique as an imaging tool for the clear identification and sensitive evaluation of very small surface cracks. The distributions of d-c potential drop around the surface cracks are obtained by scanning the closely coupled probes potential drop sensor, and a methodology for evaluating a 3-D crack from the potential drop profiles measured across and along t...

Thermosonics: Detecting Cracks and Adhesion Defects Using Ultrasonic Excitation and Infrared Imaging

We describe a new nondestructive evaluation technique which makes cracks and adhesion defects visible to infrared cameras. This is accomplished by infusing the sample with a short pulse of low frequency ultrasound. The sound causes the faying surfaces of defects to heat up by friction or clapping, and thus makes them visible in the infrared. Surface or near-surface defects appear to the camera ...

Interferometric and Holographic Imaging of Surface-Breaking Cracks

Detecting trends in cereal crop sowing dates using Landsat

Agronomic research suggests Australian farmers may increase wheat yields by 13 to 47% and reduce risk of crop failures by sowing crops earlier than is currently practiced. This study investigated the potential to use remote sensing to assist in evaluating changes in farmer sowing date practices in response to research recommendations, using study paddocks in the southern Australian cropping reg...