Nina - From Russian name Nina that comes from Slavonic ninati "nod", "doze" i.e. "dreamer". It spread due to Lermontov's "Mascarade" drama, which was staged in 1980s. It is in use now.
Petrosyan - Petrosyan, Petrosian or Petrossian (Eastern Armenian), Bedrosian or Bedrossian (Western Armenian) is a common surname in Armenia.
It is a patronymic from the Armenian first name Petros (equivalent to Peter).