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FDS13-Aquamarine
13-Aquamarine
January 15, 2021
Question

Difficulty in defining when the first deflection takes place in a plot

  • January 15, 2021
  • 1 reply
  • 3686 views

Years ago Werner helped me in setting up a technique to define the first deflection in a curve. Now I have to make a similar analysis but unfortunately the worksheet miscalculates the first deflection in 5 out of 6 plots. I was wondering whether this could be optimized? I have tried a few approaches e.g. using a higher derivative but this only marginally improved my results. I have put the correct indexes in the worksheet as correct 1 etc. Any help or suggestion to improve the method would be extremely appreciated as I have to analyse 150 plots and would like to avoid doing this manually.

Thank you in advance!

1 reply

L
LucMeekes23-Emerald IV
23-Emerald IV
January 15, 2021

How did you (independently from Werner's routine) determine the maxBend points?

With respect to set.1 you say the maxBend occurs at x=4.89 (rather than at 7.99).

Are you looking for maximum of the slope (1st derivative, I find it at about x=4.4) or maximum of the bend (2nd derivative, I find it at about x=3.3)?

 

Luc

F
FDS13-AquamarineAuthor
13-Aquamarine
January 15, 2021

Dear Luc, thank you for your reply. As you probably noted the first part of the curve is of no interest (all impedance values below 20. What I am looking for is when the upgoing curve starts to deviate towards the right. Your proposed 4.9 value is correct. I obtained the "correct" values by visual judgement as I did not succeeded in finding a better method.

L
LucMeekes23-Emerald IV
23-Emerald IV
January 15, 2021

Filip,

 

My proposed value is not 4.9, that's your result. I get 4.4 for the maximum of the first derivative, 3.3 for the maximum of the 2nd derivative.

 

Luc

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