The flash method thermal conductivity measurements.
The method is extremely elegant as it reduces a difficult thermal measurement to a much more manageable time measurement.
It is based on depositing a very short but intense energy pulse on one surface of a disk shaped sample, while monitoring the temperature excursion of the opposite face.
From the characteristic time dependence of the temperature rise, called thermogram, thermal diffusivity can be calculated. In applied physics, thermal conductivity is one of the most sought after heat transport properties for any material.