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# REDIRECTKnoop hardness test
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# and hardness
# Nuclear hardness is determined for specified or actual quantified environmental conditions and physical parameters, such as peak radiation levels, overpressure, velocities, energy absorbed, and electrical stress.
# and test
# Test that F ≠ N, that F divides N ( time complexity O ( log N )), and that F is prime ( polynomial time ; see AKS primality test ).
Ivy Mike, the first full test of the Teller – Ulam design ( a Nuclear weapon design # Two-stage thermonuclear weapons | staged fusion bomb ), with a TNT equivalent | yield of 10. 4 megatons ( November 1, 1952 )
# using a stable optical source, at the wavelength of interest, to drive a mode scrambler, the output of which overfills ( drives ) a 1 to 2 meter long reference fiber having physical and optical characteristics matching those of the fiber under test,
# subtracting the power level obtained at the output of the fiber under test from the power level obtained at the output of the reference fiber, to get the transmission loss of the fiber under test.
# The DNA is placed in test tubes containing caesium chloride ( heavy compound ) and centrifuged at 40, 000 revolutions per minute.
hardness and test
The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload.
The Brinell hardness test, invented in Sweden, was developed earlier — in 1900 — but it was slow, not useful on fully hardened steel, and left too large an impression to be considered nondestructive.
Cementite is very hard and brittle ; its hardness is about 640 by the Brinell hardness test, whereas ferrite is only 200.
It is the hardest wood that is measured using the Janka hardness test, requiring a force of to embed a steel ball in diameter a distance half of that into the wood.
Proposed by Swedish engineer Johan August Brinell in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy.
BHN is designated by the most commonly used test standards ( ASTM E10-08 and ISO 6506 – 1: 2005 ) as HBW ( H from hardness, B from brinell and W from the material of the indenter, tungsten ( wolfram ) carbide ).
When quoting a Brinell hardness number ( BHN or more commonly HB ), the conditions of the test used to obtain the number must be specified.
For example, in 1965, AFWL ’ s Civil Engineering Research Branch began studies using conventional high explosives to simulate a nuclear blast to test the hardness or survivability of underground missile silos and command centers.
With a small bottle of acid to test for carbonate of lime, a knife to ascertain the hardness of rocks and minerals, and a pocket lens to magnify their structure, the field geologist is rarely at a loss to what group a rock belongs.
The hardness of traditional bamboo flooring ranges from 1180 ( carbonized horizontal ) to around 1380 ( natural ), while newer manufacturing techniques including Fossilized ™ strand woven bamboo flooring range from 3000 to over 5000 using the Janka hardness test.
A superhard material is a material with a hardness value exceeding 40 GPa ( gigapascals ) when measured by the Vickers hardness test.
In 2002 SATRA acquired Hampden Test Equipment which supplies test machinery for hardness, resilience and abrasion measurements ; it also makes ozone cabinets, mainly for the polymer industries.
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