Figure 3
From: Spectral effectiveness of engineered thermal cloaks in the frequency regime
Standard deviation ratio of a clay homogeneous monolayer cloak (red), Pendry's cloak (green), Kohn's cloak (black) and Milton's cloak (magenta) at angular frequencies ω = 0, 0.1, 1 and 3 rad.s−1.
The source is on the left so that heat diffuses from left to right. The vertical lines are related to the position of the insulating layer and cloaks. The (z) vertical axis gives the ratio of the deviation on a logarithmic scale, while the (x) horizontal axis is for the temperature of the isotherms. Note that this temperature scale is directly connected to the x length coordinate. For the static regime for instance the temperature is 
at half of the total x length. This is no longer the case at increasing frequencies, which explains the shift of the curves with frequency ω. The horizontal dashed blue line indicates the height of minimum of the standard deviation ratio among all the studied cloaks at frequency ω.
