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 ?
Table-5: (a) Weight fraction activity coefficient a|1a of with alcohols and alkanes systems for poly (ABM).
Table-5: (b) Weight fraction activity coefficient a|1a of with alcohols and alkanes systems for poly(ABM%71-co-AN).
Then, it discusses the proposed methodology for calculating fugacity and activity coefficients in the selected binary samples, showing the main equations required for its determination.
The methodology applied takes advantage of a computational model for predicting fugacity and activity coefficients, through SFHS.
g,1] values are suitable for further thermodynamic calculations such as the solvent activity coefficients or the Flory Huggins parameters.
Computerized design of multicomponent distillation columns using the UNIFAC group contribution method for calculation of activity coefficients.
In order to have an understanding of those chemically reacting, multi-component, multiphase systems, a brief discussion about the chemical equilibria, vapour--liquid phase equilibria, thermodynamic framework, and activity coefficient model are included, which ensures an appropriate formulation of the objective function.
The activity coefficients and other thermodynamic properties of hydrochloric acid are dependent not upon the value of E[degrees] but on the difference E-E[degrees].
In the absence of the experimental vapor-liquid equilibrium data), (the activity coefficients at infinite dilution are predicted from the group contribution methods of the modified UNIFAC model proposed by Weldich et al.
By obtaining the weight fraction activity coefficient, O1 , the partial molar free energy, DG1, and the average partial molar enthalpy, DH1 values can be calculated from following relations, respectively at infinite dilution [31-33].
When an elastomer is in equilibrium with a nonideal solution, activity coefficients based upon the constituent volume fractions are introduced.