activity

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activity

1. the number of disintegrations of a radioactive substance in a given unit of time, usually expressed in curies or disintegrations per second
2. 
a. the capacity of a substance to undergo chemical change
b. the effective concentration of a substance in a chemical system. The absolute activity of a substance B, λB, is defined as exp (μBRT) where μB is the chemical potential

activity

[‚ak′tiv·əd·ē]
(computer science)
The use or modification of information contained in a file.
(nuclear physics)
The intensity of a radioactive source. Also known as radioactivity.
(physical chemistry)
A thermodynamic function that correlates changes in the chemical potential with changes in experimentally measurable quantities, such as concentrations or partial pressures, through relations formally equivalent to those for ideal systems.
(systems engineering)
The representation in a PERT or critical-path-method network of a task that takes up both time and resources and whose performance is necessary for the system to move from one event to the next.

activity

In CPM terminology, a task or item of work that must be performed in order to complete a project.
References in periodicals archive ?
Industrial activity coefficient analysis for the industry: 2008-2014
The polymer NRTL activity coefficients model interaction parameters.
iota]] is calculated from the activity coefficients predicted by the polymer NRTL model.
in the liquid phase are very low compared to the other species present in the equilibrated liquid phase, they have been neglected in the material balances and activity coefficient calculations.
Theoretical treatments of activity coefficients in nonideal solutions have been discussed for a century.
1 Comparative analysis of the industry activity coefficients 147