  We model the Neupert effect that relates flare heating energy with the
observed SXR emission. The traditional form of the Neupert effect refers to the
correlation between the time-integrated HXR or microwave light curve and the
SXR light curve. In this paper, instead, we use as the proxy for heating energy
the ultraviolet (UV) emission at the foot-points of flare loops, and modify the
model of the Neupert effect by taking into account the discrete nature of flare
heating as well as cooling. In the modified empirical model, spatially resolved
UV lightcurves from the transition region or upper chromosphere are each
convolved with a kernel function characterizing the decay of the flare loop
emission. Contributions by all loops are summed to compare with the observed
total SXR emission. The model has successfully reproduced the observed SXR
emission from its rise to decay. To estimate heating energies in flare loops,
we also employ the UV Foot-point Calorimeter (UFC) method that infers heating
rates in flare loops from these UV light curves and models evolution of flare
loops with a zero-dimensional hydrodynamic code. The experiments show that a
multitude of impulsive heating events do not well reproduce the observed flare
SXR light curve, but a two-phase heating model leads to better agreement with
observations. Comparison of the two models of the Neupert effect further allows
us to calibrate the UFC method, and improve the estimate of heating rates in
flare loops continuously formed by magnetic reconnection throughout the flare
evolution.
