[ot-users] Open Turns FORM

Douglas Long douglaslong11 at gmail.com
Sat Aug 12 23:21:39 CEST 2017


Thanks Regis! This is perfect.

I am currently travelling in Poland, I will test this later this week.


On Sat, Aug 12, 2017 at 11:20 PM regis lebrun <
regis_anne.lebrun_dutfoy at yahoo.fr> wrote:

> Hi Douglas,
>
> First of all, thanks for using OT. I checked the reference, and the method
> used is NOT the FORM approximation, but the FOSM method. Ie a linearization
> at the mean point of the input distribution and not at the most probable
> point. So you must use the TaylorExpansionMoments class instead of the FORM
> class.
> I also checked your code, and you made two mistakes in the probabilistic
> modeling:
> + the marginal distributions are not given in the correct order wrt the
> input varaibles of the model
> + the standard deviation of L is 0.1 and not 0.0001
>
> If you use correctly the TaylorExpansionMoments class (ie its
> getMeanFirstOrder() and getCovariance() methods) you get for the
> reliability index:
> Beta=2.48039658511
> And the probability (use DistFunc.pNormal() for Phi):
> P=0.00656181631695
>
> I have a very limited access to the internet for the next two weeks (and
> an old blackberry to write messages...) so I cannot send you the full
> script before the 26th of August.
>
> Best regards
>
> Regis
>
> --------------------------------------------
> En date de : Ven 4.8.17, Douglas Long <douglaslong11 at gmail.com> a écrit :
>
>  Objet: Re: [ot-users] Open Turns FORM
>  À: "Users" <users at openturns.org>
>  Cc: "regis lebrun" <regis_anne.lebrun_dutfoy at yahoo.fr>, "Philip
> Fernandes" <philf77 at gmail.com>
>  Date: Vendredi 4 août 2017, 19h48
>
>  my
>  apologies. there was a type in the distributions
>  list.import
>  openturns as ot
>
>
>  myFunction =
>  ot.NumericalMathFunction(['P',
>  'L',
>  'W',
>  'T'],
>  ['d'],
>                                        ['W*T -
>  P*L/4'])
>
>  distributions_list = [
>  ot.Normal(0.0001, 0.00002),
>  ot.Normal(600000, 100000),
>  ot.Normal(10, 2),
>  ot.Normal(8, 0.0001)
>  ]
>  copula =
>  ot.IndependentCopula(4)
>  compose_distribution =
>  ot.ComposedDistribution(distributions_list, copula)
>
>
>  vect =
>  ot.RandomVector(compose_distribution)
>  output
>  = ot.RandomVector(myFunction, vect)
>  myEvent
>  = ot.Event(output, ot.Less(), 0)
>
>  myCobyla = ot.Cobyla()
>  myAlgo =
>  ot.FORM(myCobyla, myEvent, [0.0001,600000,10,8])
>  myAlgo.run()
>  result =
>  myAlgo.getResult()
>
>  print(result.getPhysicalSpaceDesignPoint())
>  print(result.getHasoferReliabilityIndex())
>  print(result.getEventProbability())
>  print(result.getLimitStateVariable())
>  print(result.getStandardSpaceDesignPoint())
>  print(result.getImportanceFactors())
>  On Fri, Aug 4, 2017 at
>  11:38 AM, Douglas Long <douglaslong11 at gmail.com>
>  wrote:
>  Hey Folks,
>  I am
>  attempting to recreate a FORM example.http://www2.mae.ufl.edu/
>  haftka/stropt/Lectures/FORM. pdfI am trying to
>  get BETA = 2.48 as in the example linked
>  above.
>
>  here is my code but my results are
>  different. I have tried many different
>  solutions.any help would be greatly
>  appreciated.
>  Thanks,Dougimport
>  openturns as ot
>
>
>  myFunction =
>  ot.NumericalMathFunction(['P',
>  'L',
>  'W',
>  'T'],
>  ['d'],
>                                        ['W*T -
>  P*L/4'])
>
>  distributions_list = [
>  ot.Normal(0.0001, 2),
>  ot.Normal(600000, 0.1),
>  ot.Normal(10, 0.00002),
>  ot.Normal(8, 100000)
>  ]
>  copula =
>  ot.IndependentCopula(4)
>  compose_distribution = ot.ComposedDistribution(
>  distributions_list, copula)
>
>
>  vect =
>  ot.RandomVector(compose_ distribution)
>  output = ot.RandomVector(myFunction, vect)
>  myEvent = ot.Event(output, ot.Less(), 0)
>
>  myCobyla = ot.Cobyla()
>  myAlgo =
>  ot.FORM(myCobyla, myEvent, [0.0001,600000,10,8])
>  myAlgo.run()
>  result =
>  myAlgo.getResult()
>
>  print(result.
>  getPhysicalSpaceDesignPoint())
>  print(result.
>  getHasoferReliabilityIndex())
>  print(result.
>  getEventProbability())
>  print(result.
>  getLimitStateVariable())
>  print(result.
>  getStandardSpaceDesignPoint())
>  print(result.
>  getImportanceFactors())
>
>  --
>
>  Douglas
>  Long
>  douglaslong11 at gmail.com
>
>
>
>
>  --
>  Douglas Long
>  douglaslong11 at gmail.com
>  _______________________________________________
>  OpenTURNS users mailing list
>  users at openturns.org
>  http://openturns.org/mailman/listinfo/users
>
>  -----La pièce jointe associée suit-----
>
>
> --
Douglas Long
douglaslong11 at gmail.com
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