14,321 research outputs found
Nonlocal Flow of Convex Plane Curves and Isoperimetric Inequalities
In the first part of the paper we survey some nonlocal flows of convex plane
curves ever studied so far and discuss properties of the flows related to
enclosed area and length, especially the isoperimetric ratio and the
isoperimetric difference. We also study a new nonlocal flow of convex plane
curves and discuss its evolution behavior. In the second part of the paper we
discuss necessary and sufficient conditions (in terms of the (mixed)
isoperimetric ratio or (mixed) isoperimetric difference) for two convex closed
curves to be homothetic or parallel.Comment: 23 page
Semi-Supervised Domain Adaptation with Source Label Adaptation
Semi-Supervised Domain Adaptation (SSDA) involves learning to classify unseen
target data with a few labeled and lots of unlabeled target data, along with
many labeled source data from a related domain. Current SSDA approaches usually
aim at aligning the target data to the labeled source data with feature space
mapping and pseudo-label assignments. Nevertheless, such a source-oriented
model can sometimes align the target data to source data of the wrong classes,
degrading the classification performance. This paper presents a novel
source-adaptive paradigm that adapts the source data to match the target data.
Our key idea is to view the source data as a noisily-labeled version of the
ideal target data. Then, we propose an SSDA model that cleans up the label
noise dynamically with the help of a robust cleaner component designed from the
target perspective. Since the paradigm is very different from the core ideas
behind existing SSDA approaches, our proposed model can be easily coupled with
them to improve their performance. Empirical results on two state-of-the-art
SSDA approaches demonstrate that the proposed model effectively cleans up the
noise within the source labels and exhibits superior performance over those
approaches across benchmark datasets. Our code is available at
https://github.com/chu0802/SLA .Comment: Accepted by CVPR 202
Surface and Edge States in Topological Semi-metals
We study the topologically non-trivial semi-metals by means of the 6-band
Kane model. Existence of surface states is explicitly demonstrated by
calculating the LDOS on the material surface. In the strain free condition,
surface states are divided into two parts in the energy spectrum, one part is
in the direct gap, the other part including the crossing point of surface state
Dirac cone is submerged in the valence band. We also show how uni-axial strain
induces an insulating band gap and raises the crossing point from the valence
band into the band gap, making the system a true topological insulator. We
predict existence of helical edge states and spin Hall effect in the thin film
topological semi-metals, which could be tested with future experiment. Disorder
is found to significantly enhance the spin Hall effect in the valence band of
the thin films
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