535 research outputs found
Potential barrier of Graphene edges
We calculated row resolved density of states, charge distribution and work
function of graphene's zigzag and armchair edge (either clean or terminated
alternatively with H, O or OH group). The zigzag edge saturated via OH group
has the lowest work function of 3.76 eV, while the zigzag edge terminated via O
has the highest work function of 7.74 eV. The angle-dependent potential barrier
on the edge is fitted to a multi-pole model and is explained by the charge
distribution.Comment: 16 pages, 8 figures. Copyright (2011) American Institute of Physics.
This article may be downloaded for personal use only. Any other use requires
prior permission of the author and the American Institute of Physics. This
article appeared in (J. Appl. Phys. 109 (2011) 114308) and may be found at
(http://link.aip.org/link/?JAP/109/114308
Analytical treatment of cold field electron emission from a nanowall emitter
This paper presents an elementary, approximate analytical treatment of cold
field electron emission (CFE) from a classical nanowall. A simple model is used
to bring out some of the basic physics of a class of field emitter where
quantum confinement effects exist transverse to the emitting direction. A
high-level methodology is presented for developing CFE equations more general
than the usual Fowler-Nordheim-type (FN-type) equations, and is applied to the
classical nanowall. If the nanowall is sufficiently thin, then significant
transverse-energy quantization effects occur, and affect the overall form of
theoretical CFE equations; also, the tunnelling barrier shape exhibits
"fall-off" in the local field value with distance from the surface. A conformal
transformation technique is used to derive an analytical expression for the
on-axis tunnelling probability.Comment: 48 pages, 4 figure
Efficient vanishing point detection method in unstructured road environments based on dark channel prior
Vanishing point detection is a key technique in the fields such as road detection, camera calibration and visual navigation. This study presents a new vanishing point detection method, which delivers efficiency by using a dark channel priorābased segmentation method and an adaptive straight lines search mechanism in the road region. First, the dark channel prior information is used to segment the image into a series of regions. Then the straight lines are extracted from the region contours, and the straight lines in the road region are estimated by a vertical envelope and a perspective quadrilateral constraint. The vertical envelope roughly divides the whole image into sky region, vertical region and road region. The perspective quadrilateral constraint, as the authors defined herein, eliminates the vertical lines interference inside the road region to extract the approximate straight lines in the road region. Finally, the vanishing point is estimated by the meanshift clustering method, which are computed based on the proposed grouping strategies and the intersection principles. Experiments have been conducted with a large number of road images under different environmental conditions, and the results demonstrate that the authorsā proposed algorithm can estimate vanishing point accurately and efficiently in unstructured road scenes
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