• It has been found ( or established , or ascertained ) that ...
• It turns out ( or It appears ) that in a wave guide the group velocity is equal to ...
• It has been found ( or established , or ascertained ) that ...
• It turns out ( or It appears ) that in a wave guide the group velocity is equal to ...
Циммерман М., Веденеева К.. Русско-Английский научно-технический словарь переводчика. Russian-English scientific dictionary for translators. 2012