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Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic tape can with relative ease record and play back audio, visual, and binary computer data.
This method is unaffected by all non conductive materials such as concrete, wood, plastics, bricks, etc. However any kind of conductive materials within the magnetic field will have an influence on the measurement. Advantages of the pulse induction method: high accuracy; not influenced by moisture and heterogeneities of the concrete [2]
Magnetic media also deteriorates naturally with typical shelf lives between 10 and 20 years. [7] Magnetic tape can degrade from binder hydrolysis or magnetic remanence decay. Binder hydrolysis, also known as sticky-shed syndrome, refers to the breakdown of binder, or glue, that holds the magnetic particles to the polyester base of the tape ...
English: The "Bache method" for testing concrete durability, which simulates daily temperature variations in brine. Test 1 or 2 (each 24 h) may be used, or both performed sequentially during a 48-hour period. The chosen cycle is repeated ad nauseam in order to determine the mass-loss, as an analogue for durability.
After World War II, the advantages of tape in terms of sturdiness and the ability to edit by cutting and splicing made tape preferable to wire as the magnetic medium of choice. Tape consists of a coating of a magnetic pigment, typically iron oxide ( Fe 2 O 3 ), on a long strip of polyester (polyethelyne terephthalate) base film.
Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than one (or, equivalently, a positive magnetic susceptibility). The magnetic moment induced by the applied field is linear in the field strength, and it is rather weak. It typically requires a sensitive analytical balance to detect the ...
Coercivity in a ferromagnetic material is the intensity of the applied magnetic field (H field) required to demagnetize that material, after the magnetization of the sample has been driven to saturation by a strong field. This demagnetizing field is applied opposite to the original saturating field.
Detectable tape or Underground warning tape is a conductive tape typically applied over buried utilities made of non-conductive materials such as plastic, fiberglass, or cement. It is used because most utility location methods work best on conductive objects, and hence may easily miss structures made of non-conductive materials.