Fig. 7. The temperature (T) distribution along the direction of the sensing needle in a parallelepiped (5 by 5 by 5 cm³) with time t = 60 s for zero surface temperature (ZST, dotted lines) and adiabatic boundary conditions (ABC, solid lines). The numbers on the curves are the values of (a) needle spacing with fixed probe length (c₀ = 4 cm) and (b) probe length with fixed needle spacing (r = 6 mm). The point T_ILS on the curve denotes the temperature of an infinite line source.