Question on Second Order Reliability Method (FORM) Theory in UQLab V2.1

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1

Hy everyone. I was reading the last publication UQLAB USER MANUAL STRUCTURAL RELIABILITY (RARE EVENT ESTIMATION) where the SORM start with:

image
image814×42 5.24 KB

and subsequently the condition of the Equation 1.30:
image
image807×40 2.9 KB

And subsequently Equation 1.29 rewritten as:

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image830×193 32.5 KB

My questions are:

  1. For the definition of V_m to be correct, Equation 1.30 should not be U=Q^TV ?
  2. And what is the reason for the disappearance of the transpose of (U-U)^T from Equation 1.29 to Equation 1.31?

Thanks and regards.