This paper describes a new semi-coherent method to search for transient
gravitational waves of intermediate duration (hours to days). In order to
search for newborn isolated neutron stars with their possibly very rapid
spin-down, we model the frequency evolution as a power law. The search uses
short Fourier transforms from the output of ground-based gravitational wave
detectors and applies a weighted Hough transform, also taking into account the
signal's amplitude evolution. We present the technical details for implementing
the algorithm, its statistical properties, and a sensitivity estimate. A first
example application of this method was in the search for GW170817 post-merger
signals, and we verify the estimated sensitivity with simulated signals for
this case.Comment: 13 pages, 14 figure
