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On Windows NT operating systems, CHKDSK can also check the disk surface for bad sectors and mark them (in MS-DOS 6.x and Windows 9x, this is a task done by Microsoft ScanDisk). The Windows Server version of CHKDSK is RAID -aware and can fully recover data in bad sectors of a disk in a RAID-1 or RAID-5 array if other disks in the set are intact.
The defect or discontinuity creates a characteristic parabolic indication, due to the apparent change in depth as the probes travel. Manually-guided TOFD probes. Time-of-flight diffraction (TOFD) method of ultrasonic testing is a sensitive and accurate method for the nondestructive testing of welds for defects.
The disadvantage is a longer measurement time and dependence of detection capabilities on a geometrical orientation of defects (except of an indirect excitation such as ultrasound). The Lock-In method is suitable for testing components with a low thermal diffusivity and it has many modifications for various specific applications (such as Lock ...
Scandisk was a replacement for the chkdsk utility, starting with MS-DOS version 6.2 and later. [1] Its primary advantages over chkdsk is that it is more reliable and has the ability to run a surface scan which finds and marks bad clusters on the disk.
Eddy Current systems for the detection of near-surface defects. There are many manufacturers of road/rail inspection trucks, otherwise known as HiRail trucks. These HiRail inspection cars are almost all ultrasonic testing exclusively, but there are some with the capability to perform multiple tests.
The notion of acoustic microscopy dates back to 1936 when S. Ya. Sokolov [1] proposed a device for producing magnified views of structure with 3-GHz sound waves. However, due to technological limitations at the time, no such instrument could be constructed, and it was not until 1959 that Dunn and Fry [2] performed the first acoustic microscopy experiments, though not at very high frequencies.
Visibility of defects; types of defect images [ edit ] To discuss the visibility of defects in topographic images according to theory, consider the exemplary case of a single dislocation : It will give rise to contrast in topography only if the lattice planes involved in diffraction are distorted in some way by the existence of the dislocation.
Variations in the electrical conductivity and magnetic permeability of the test object, and the presence of defects causes a change in eddy current and a corresponding change in phase and amplitude that can be detected by measuring the impedance changes in the coil, which is a telltale sign of the presence of defects. [5]