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Activity levels, after being normalized to δ 13 C of -25‰, can be divided by this in order to calculate the "radiocarbon age". But as part of their methodology both beta counting and AMS measure standard samples containing carbon of a known activity, and the activity of the sample is divided by the activity of the standard. [8]
C, which are used to calculate Fm, the "fraction modern". This is defined as the ratio between the 14 C / 12 C ratio in the sample and the 14 C / 12 C ratio in modern carbon, which is in turn defined as the 14 C / 12 C ratio that would have been measured in 1950 had there been no fossil fuel effect. [73]
A polarity excursion, which can be either global or local, is a shorter-lived version of a geomagnetic reversal. A local excursion would not significantly affect 14C production. During either a geomagnetic reversal or a global polarity excursion, 14 C production increases during the period when the geomagnetic field is weak. It is fairly ...
Radiocarbon dating measurements produce ages in "radiocarbon years", which must be converted to calendar ages by a process called calibration.Calibration is needed because the atmospheric 14
Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
Creep and shrinkage of concrete are two physical properties of concrete. The creep of concrete, which originates from the calcium silicate hydrates (C-S-H) in the hardened Portland cement paste (which is the binder of mineral aggregates), is fundamentally different from the creep of metals and polymers.
Concrete spalling from the ceiling of an office unit (interior) in Singapore, possibly due to rebar corrosion. Reinforced concrete can fail due to inadequate strength, leading to mechanical failure, or due to a reduction in its durability. Corrosion and freeze/thaw cycles may damage poorly designed or constructed reinforced concrete.
The same example using first pass yield (FPY) would take into account rework: (# units leaving process A as good parts with no rework) / (# units put into the process) 100 units enter process A, 5 were reworked, and 90 leave as good parts. The FPY for process A is (90-5)/100 = 85/100 = 0.8500