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  2. Dynamic factor - Wikipedia

    en.wikipedia.org/wiki/Dynamic_factor

    In econometrics, a dynamic factor (also known as a diffusion index) is a series which measures the co-movement of many time series. It is used in certain macroeconomic models. A diffusion index is intended to indicate the changes of the fraction of economic data time series which increase or decrease over the selected time interval,

  3. Doubling time - Wikipedia

    en.wikipedia.org/wiki/Doubling_time

    For example, with an annual growth rate of 4.8% the doubling time is 14.78 years, and a doubling time of 10 years corresponds to a growth rate between 7% and 7.5% (actually about 7.18%). When applied to the constant growth in consumption of a resource, the total amount consumed in one doubling period equals the total amount consumed in all ...

  4. Crack growth equation - Wikipedia

    en.wikipedia.org/wiki/Crack_growth_equation

    A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. The growth of a fatigue crack can result in catastrophic failure, particularly in the case of aircraft. When many growing fatigue cracks interact with one another it is known as widespread fatigue damage. A crack growth equation can be used to ...

  5. Dynamic amplification factor - Wikipedia

    en.wikipedia.org/wiki/Dynamic_amplification_factor

    Dynamic Amplification Factor (DAF) or Dynamic Increase Factor (DIF), is a dimensionless number which describes how many times the deflections or stresses should be multiplied to the deflections or stresses caused by the static loads when a dynamic load is applied on to a structure. [1]

  6. Population dynamics - Wikipedia

    en.wikipedia.org/wiki/Population_dynamics

    Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems.Population dynamics is a branch of mathematical biology, and uses mathematical techniques such as differential equations to model behaviour.

  7. Relative growth rate - Wikipedia

    en.wikipedia.org/wiki/Relative_growth_rate

    When calculating or discussing relative growth rate, it is important to pay attention to the units of time being considered. [ 2 ] For example, if an initial population of S 0 bacteria doubles every twenty minutes, then at time interval t {\displaystyle t} it is given by solving the equation:

  8. Fanning friction factor - Wikipedia

    en.wikipedia.org/wiki/Fanning_friction_factor

    The Fanning friction factor (named after American engineer John T. Fanning) is a dimensionless number used as a local parameter in continuum mechanics calculations. It is defined as the ratio between the local shear stress and the local flow kinetic energy density: [1] [2]

  9. Population dynamics of fisheries - Wikipedia

    en.wikipedia.org/wiki/Population_dynamics_of...

    A fishery population is affected by three dynamic rate functions: Birth rate or recruitment. Recruitment means reaching a certain size or reproductive stage. With fisheries, recruitment usually refers to the age a fish can be caught and counted in nets. Growth rate. This measures the growth of individuals in size and length.