Regulators on Dec. 24, 2013, approved a price hike of 3 cents for a first-class stamp, bringing the charge to 49 cents a letter in an effort to help the Postal Service recover from severe mail decreases brought on after the 2008 economic downturn.
C-value â Thermal Conductance. Thermal conductance is the time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces, in W/m2âK. C-value, hence, is the reciprocal of the R-value and can be expressed as Equation (3).
thermal diffusivity describes how easily heat diffuses throughout the material, so it depends on thermal conductivity and specific heat. thermal diffusivity = thermal conductivity / ( density *specific heat ) specific heat is the amount od energy required to raise the temperature of a substance by 1 degree.