"validation has been" is a valid phrase and can be used in written English.
Example: The validation has been completed and the document is now ready to be submitted.
Validation has been achieved through extensive experiments.
However, relatively little validation has been performed.
Code validation has been carried out against experimental data.
Experimental validation has been done at two different cases.
Scientifically, the process of biomarker discovery and validation has been disappointingly slow.
Furthermore, minimal validation has been done on most of these datasets.
The method validation has been done for a 1 M NaOH solution at 25°C.
In addition, an external validation has been done using photographs taken directly from the olive grove.
Validation has been done with in situ data for different agricultural landscapes over China.
The initial process validation has been presented by using SU-8 material.
An experimental validation has been carried out for each configuration while replicating human-like basic movements.
