vallenae.timepicker.hinkley

vallenae.timepicker.hinkley(arr, alpha=5)[source]

Hinkley criterion for arrival time estimation.

The Hinkley criterion is defined as the partial energy of the signal (cumulative square sum) with an applied negative trend (characterized by alpha).

The starting value of alpha is reduced iteratively to avoid wrong picks within the pre-trigger part of the signal. Usually alpha values are chosen to be between 2 and 200 to ensure minimal delay. The chosen alpha value for the Hinkley criterion influences the results significantly.

Parameters:

  • arr (ndarray) – Transient signal of hit

  • alpha (int) – Divisor of the negative trend. Default: 5

Return type:

Tuple[ndarray, int]

Returns:

  • Array with computed detection function

  • Index of the estimated arrival time (max value)

References

  • Molenda, M. (2016). Acoustic Emission monitoring of laboratory hydraulic fracturing experiments. Ruhr-Universität Bochum.

  • van Rijn, N. (2017). Investigating the Behaviour of Acoustic Emission Waves Near Cracks: Using the Finite Element Method. Delft University of Technology.