scratch

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scratch

1. Billiards snooker
a. a shot that results in a penalty, as when the cue ball enters the pocket
b. a lucky shot
2. poultry food

scratch

[skrach]
(computer science)
To remove data or to set up its identifying labels so that new data can be written over it.

scratch

To score or groove a plaster surface to provide a better bond for the succeeding coat.

compressor blade damage

compressor blade damageclick for a larger image
Various types of damages that compressor blades can sustain. Only one or two may take place simultaneously though these have been combined in this illustration.
The various types of damages to compressor blades and their appearances are as follows:
i. Bend. The blade gives the appearance of ragged edges. Smooth repair of the edges or surface in question can be carried out, but the extent of the damage that can be repaired is limited.
ii. Bow. The main source of this type of damage is a foreign object. The blade is bent at the tips and the edges.
iii. Burning. The damage is caused by overheating. The surface of the blade is discolored. If the overheating is severe, there may be some flow of material as well.
iv. Burr. A ragged or turn-out edge is indicative of this type of damage. This takes place during the grinding or cutting operation of the blade at the manufacturing stage.
v. Corrosion. Oxidants and corrosive agents, especially moisture present in the atmosphere, are the main reasons for the corrosion or pitting of the blades. Normally, regular washing is sufficient to prevent it. The blade gives a pitted appearance, and there is some breakdown of the surface of the blade. Also called pitting.
vi. Cracks. Excessive stress from shocks, overloading, or faulty processing of blades during manufacturing can cause cracks and result in their fracture.
vii. Dent. These can be caused by FOD (foreign-object damage) or strikes by dull objects like those in bird strikes. Minor dents can be repaired.
viii. Gall. This type of damage is from the severe rubbing of blades, in which a transfer of metal from one surface to another takes place.
ix. Gouging. The blade gives the appearance of displacing material from its surface, and a tearing effect is prominently visible. This type of damage is from the presence of a comparatively large cutting material or foreign body between moving parts.
x. Growth. The damage manifests itself in the form of elongation of the blades. Growth type of damage takes place because of continued and/or excessive heat and centrifugal force.
xi. Score. Deep scratches are indicative of scoring, which is caused by the presence of chips between surfaces.
xii. Scratch. Narrow and shallow scratches are caused by sand or fine foreign particles as well as by mishandling the blades.
xiii. Pitting. Pitting takes place because of atmospheric corrosion, especially seawater. The surface of the blade shows signs of pitting.

scratch

(1)
(From "scratchpad") Describes a data structure or recording medium attached to a machine for testing or temporary-use purposes; one that can be scribbled on without loss. Usually in the combining forms "scratch memory", "scratch register", "scratch disk", "scratch tape", "scratch volume".

See also scratch monkey.

scratch

(2)
(primarily IBM) To delete (as in a file).

Scratch

A visual programming language for creating animations, developed at MIT and introduced in 2007. A Scratch script is coded by dragging predefined action commands into a work area. Used in schools, colleges and community centers to create games, animations and infographics, Scratch is also used to teach basic programming concepts. See scratch disk.


Scratch Motion Commands
After dragging "Move 10 Steps" to the work area and changing 10 to 25, clicking the command moves the cat "costume" 25 steps across the stage. Users can create their own costumes, but Scratch comes with hundreds to choose from.