7,969 research outputs found
Priming Neural Networks
Visual priming is known to affect the human visual system to allow detection
of scene elements, even those that may have been near unnoticeable before, such
as the presence of camouflaged animals. This process has been shown to be an
effect of top-down signaling in the visual system triggered by the said cue. In
this paper, we propose a mechanism to mimic the process of priming in the
context of object detection and segmentation. We view priming as having a
modulatory, cue dependent effect on layers of features within a network. Our
results show how such a process can be complementary to, and at times more
effective than simple post-processing applied to the output of the network,
notably so in cases where the object is hard to detect such as in severe noise.
Moreover, we find the effects of priming are sometimes stronger when early
visual layers are affected. Overall, our experiments confirm that top-down
signals can go a long way in improving object detection and segmentation.Comment: fixed error in author nam
Dimensional crossover of the fundamental-measure functional for parallel hard cubes
We present a regularization of the recently proposed fundamental-measure
functional for a mixture of parallel hard cubes. The regularized functional is
shown to have right dimensional crossovers to any smaller dimension, thus
allowing to use it to study highly inhomogeneous phases (such as the solid
phase). Furthermore, it is shown how the functional of the slightly more
general model of parallel hard parallelepipeds can be obtained using the
zero-dimensional functional as a generating functional. The multicomponent
version of the latter system is also given, and it is suggested how to
reformulate it as a restricted-orientation model for liquid crystals. Finally,
the method is further extended to build a functional for a mixture of parallel
hard cylinders.Comment: 4 pages, no figures, uses revtex style files and multicol.sty, for a
PostScript version see http://dulcinea.uc3m.es/users/cuesta/cross.p
Tidal band current variability over the Northern California continental shelf
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution December 1986The focus of this dissertation is on the description and dynamical
interpretation of the tidal band current fluctuations over the
continental shelf off northern California. The term "tidal band" is
used here to denote fluctuations with periods from about one-half to
one day, including all the major diurnal and semidiurnal tidal
constituents. The semidiurnal frequency is super-inertial, and the
diurnal frequency sub-inertial, at this mid-latitude location.
Kinetic and potential energy are strongly peaked at the diurnal and
semidiurnal frequencies. Although inertial currents are occasionally
observed, particularly during the winter when internal wave energy in
general is elevated in this locale, they do not contribute
significantly to the current variance. Consequently, the treatment
here is divided into discussion of the diurnal and semidiurnal
variability. Each chapter emphasizes a process which can cause the
tidal currents to deviate from what would be anticipated based solely
on observations of sea level. In Chapter II, the diurnal current
variability is discussed, and the role played by atmospheric forcing
is examined in detail. In Chapter III, the barotropic semidiurnal
tidal currents over the shelf are described, and the effect of
small-scale bumps in the coastline is evaluated. The baroclinic
semi diurnal tidal currents, which are dependent upon the local
time-varying hydrographic conditions, are examined in Chapter IV.Support from the WHOI
Education Office, a NASA traineeship, and NSF grants OCE 80-14941 and
OCE 84-17769
Transport and stirring induced by vortex formation
The purpose of this study is to analyse the transport and stirring of fluid that occurs owing to the formation and growth of a laminar vortex ring. Experimental data was collected upstream and downstream of the exit plane of a piston-cylinder apparatus by particle-image velocimetry. This data was used to compute Lagrangian coherent structures to demonstrate how fluid is advected during the transient process of vortex ring formation. Similar computations were performed from computational fluid dynamics (CFD) data, which showed qualitative agreement with the experimental results, although the CFD data provides better resolution in the boundary layer of the cylinder. A parametric study is performed to demonstrate how varying the piston-stroke length-to-diameter ratio affects fluid entrainment during formation. Additionally, we study how regions of fluid are stirred together during vortex formation to help establish a quantitative understanding of the role of vortical flows in mixing. We show that identification of the flow geometry during vortex formation can aid in the determination of efficient stirring. We compare this framework with a traditional stirring metric and show that the framework presented in this paper is better suited for understanding stirring/mixing in transient flow problems. A movie is available with the online version of the paper
Constraints on a scalar-pseudoscalar Higgs mixing at future e+e- colliders: an update
We perform an update of our previous analysis on the constraints on possible
deviations of Hbb coupling from its Standard Model value, arising from a
scalar-pseudoscalar mixing. In this paper we include a complete simulation of
the process e+ e- -> b bbar e+ e- and combine it with our previous results to
obtain tighter bounds on the deviations of the parameters describing this
coupling that could be measured at the Next Linear Collider.Comment: 3 pages, 2 figures, to be submitted to Phys. Rev.
Discovery limits for Techni-Omega production in Collisions
In a strongly-interacting electroweak sector with an isosinglet vector state,
such as the techni-omega, , the direct coupling
implies that an can be produced by fusion in
collisions. This is a unique feature for high energy or
colliders operating in an mode. We consider the processes and , both of which proceed via
an intermediate . We find that at a 1.5 TeV linear collider
operating in an mode with an integrated luminosity of 200 fb,
we can discover an for a broad range of masses and widths.Comment: To appear in the Proceedings of the 29th International Conference on
High Energy Physics, Vancouver, July 1998, 5 pages, Latex, 7 postscript
figure
- …