  The formation of dust gaps in protoplanetary disks is one of the most
important signposts of disk evolution and possibly the formation of planets. We
aim to characterize the 'flaring' disk structure around the Herbig Ae/Be stars
HD 100453 and HD 34282. Their spectral energy distributions (SEDs) show an
emission excess between 15-40{\mu}m, but very weak (HD 100453) and no (HD
34282) signs of the 10 and 20 {\mu}m amorphous silicate features. We
investigate whether this implies the presence of large dust gaps. In this work,
spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE
are investigated. We perform radiative transfer modeling and examine the radial
distribution of dust. We simultaneously fit the Q-band images and SEDs of HD
100453 and HD 34282. Our solutions require that the inner-halos and outer-disks
are likely separated by large dust gaps that are depleted wih respect to the
outer disk by a factor of 1000 or more. The inner edges of the outer disks of
HD 100453 and HD 34282 have temperatures of about $160 \pm 10$ K and $60 \pm 5$
K respectively. Because of the high surface brightnesses of these walls, they
dominate the emission in the Q-band. Their radii are constrained at 20+2 AU and
92+31 AU, respectively. We conclude that, HD 100453 and HD 34282 likely have
disk dust gaps and the upper limit on the dust mass in each gap is estimated to
be about $10^{-7}$M$_{\odot}$. We find that the locations and sizes of disk
dust gaps are connected to the SED, as traced by the mid-infrared flux ratio
F30/F13.5. We propose a new classification scheme for the Meeus groups (Meeus
et al. 2001) based on the F30/F13.5 ratio. The absence of amorphous silicate
features in the observed SEDs is caused by the depletion of small (smaller than
1 {\mu}m) silicate dust at temperatures above 160 K, which could be related to
the presence of a dust gap in that region of the disk.
