In this paper, the authors claim in the abstract and the conclusion that the “solution with dual phase lag depends only on the difference between the two lags.” Then, they proceed to derive an integral solution for the temperature history.

I show first that this conclusion is erroneous and second that the Laplace transform method they use is incorrect.

The authors claim that the system of the dual lag Eqs. (1) and (3) in their paper is equivalent to the new system of Eqs. (6) and (7) in their paper. This is quite incorrect for the following reasons:

• 1

To obtain Eq. (6) from Eq. (1), the authors perform the shift in time $told+τq⇒tnew$, where $told$ corresponds to the time in Eq. (1) and $tnew$ is the time in Eq....