Logarithmic energy decrement

High logarithmic energy decrement to maximize the energy loss per collision due to low mass number... 

Values of the average logarithmic energy decrement as defined by Eq. (57.15), and of n, the average number of collisions required to moderate a neutron from an initial energy of 2 MeV to thermal energy as defined by Eq. (57.17), for various elements of interest in reactor technology... 

Moderating properties of different compounds scattering cross section for epithermal neutrons (er in barn) absorption cross section for thermal neutrons (average logarithmic energy decrement slowing down power (SDP) (cm ) and moderating ratio (MR)... 

Since is the average logarithmic energy decrement, the number of collisions is... 

Table 3.1. Values of Average Logarithmic Energy Decrement...

Logarithmic decrement A measure of the ability of the overall structure (vessel, foundation, insulation, contents, soil, lining, and internal and external attachments) to dissipate energy during vibration. The logarithmic ratio of two successive amplitudes of a damped, freely vibrating structure or the percentage decay per cycle. 

Usually, for a given energy, the maximum amplitude of vibration occurs at the resonant frequency, and the logarithmic decrement for a resonance curve is given by the equation ... 

It is the main objective of this example to show that some d5mamic characteristics of a structure with dampers, modelled using the above mentioned models is practically identical if both models possess approximately equal possibilities to dissipate energy. This conclusion is supported by the results presented in Table 4. This table contains logarithmic decrements of damping and the peak values of displacements and accelerations of the fourth-floor, calculated from the obtained solutions to the equations of motion for both damper models. 

Find the nnmber N of total oscillations of a system during which the system energy decreases by n = 2 times. The logarithmic decrement of damping A = 0.01. 

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