31,064 research outputs found
Single-Strip Triangulation of Manifolds with Arbitrary Topology
Triangle strips have been widely used for efficient rendering. It is
NP-complete to test whether a given triangulated model can be represented as a
single triangle strip, so many heuristics have been proposed to partition
models into few long strips. In this paper, we present a new algorithm for
creating a single triangle loop or strip from a triangulated model. Our method
applies a dual graph matching algorithm to partition the mesh into cycles, and
then merges pairs of cycles by splitting adjacent triangles when necessary. New
vertices are introduced at midpoints of edges and the new triangles thus formed
are coplanar with their parent triangles, hence the visual fidelity of the
geometry is not changed. We prove that the increase in the number of triangles
due to this splitting is 50% in the worst case, however for all models we
tested the increase was less than 2%. We also prove tight bounds on the number
of triangles needed for a single-strip representation of a model with holes on
its boundary. Our strips can be used not only for efficient rendering, but also
for other applications including the generation of space filling curves on a
manifold of any arbitrary topology.Comment: 12 pages, 10 figures. To appear at Eurographics 200
Pushing the Limits of 3D Color Printing: Error Diffusion with Translucent Materials
Accurate color reproduction is important in many applications of 3D printing,
from design prototypes to 3D color copies or portraits. Although full color is
available via other technologies, multi-jet printers have greater potential for
graphical 3D printing, in terms of reproducing complex appearance properties.
However, to date these printers cannot produce full color, and doing so poses
substantial technical challenges, from the shear amount of data to the
translucency of the available color materials. In this paper, we propose an
error diffusion halftoning approach to achieve full color with multi-jet
printers, which operates on multiple isosurfaces or layers within the object.
We propose a novel traversal algorithm for voxel surfaces, which allows the
transfer of existing error diffusion algorithms from 2D printing. The resulting
prints faithfully reproduce colors, color gradients and fine-scale details.Comment: 15 pages, 14 figures; includes supplemental figure
Fluorescence correlation spectroscopy in thin films at reflecting substrates as a means to study nanoscale structure and dynamics at soft-matter interfaces
Structure and dynamics at soft-matter interfaces play an important role in
nature and technical applications. Optical single-molecule investigations are
non-invasive and capable to reveal heterogeneities at the nanoscale. In this
work we develop an autocorrelation function (ACF) approach to retrieve tracer
diffusion parameters obtained from fluorescence correlation spectroscopy (FCS)
experiments in thin liquid films at reflecting substrates. This approach then
is used to investigate structure and dynamics in 100 nm thick 8CB liquid
crystal films on silicon wafers with five different oxide thicknesses. We find
a different extension of the structural reorientation of 8CB at the
solid-liquid interface for thin and for thick oxide. For the thin oxides, the
perylenediimide tracer diffusion dynamics in general agrees with the
hydrodynamic modeling using no-slip boundary conditions with only a small
deviation close to the substrate, while a considerably stronger decrease of the
interfacial tracer diffusion is found for the thick oxides.Comment: 8 figure
Adsorbate surface diffusion: The role of incoherent tunneling in light particle motion
The role of incoherent tunneling in the diffusion of light atoms on surfaces
is investigated. With this purpose, a Chudley-Elliot master equation
constrained to nearest neighbors is considered within the Grabert-Weiss
approach to quantum diffusion in periodic lattices. This model is applied to
recent measurements of atomic H and D on Pt(111), rendering friction
coefficients that are in the range of those available in the literature for
other species of adsorbates. A simple extension of the model has also been
considered to evaluate the relationship between coverage and tunneling, and
therefore the feasibility of the approach. An increase of the tunneling rate
has been observed as the surface coverage decreases.Comment: 7 pages, 2 figures; important reorganization of the work (including
title changes
Binary Atomic Silicon Logic
It has long been anticipated that the ultimate in miniature circuitry will be
crafted of single atoms. Despite many advances made in scanned probe microscopy
studies of molecules and atoms on surfaces, challenges with patterning and
limited thermal stability have remained. Here we make progress toward those
challenges and demonstrate rudimentary circuit elements through the patterning
of dangling bonds on a hydrogen terminated silicon surface. Dangling bonds
sequester electrons both spatially and energetically in the bulk band gap,
circumventing short circuiting by the substrate. We deploy paired dangling
bonds occupied by one movable electron to form a binary electronic building
block. Inspired by earlier quantum dot-based approaches, binary information is
encoded in the electron position allowing demonstration of a binary wire and an
OR gate
Distinguishing step relaxation mechanisms via pair correlation functions
Theoretical predictions of coupled step motion are tested by direct STM
measurement of the fluctuations of near-neighbor pairs of steps on
Si(111)-root3 x root3 R30 - Al at 970K. The average magnitude of the
pair-correlation function is within one standard deviation of zero, consistent
with uncorrelated near-neighbor step fluctuations. The time dependence of the
pair-correlation function shows no statistically significant agreement with the
predicted t^1/2 growth of pair correlations via rate-limiting atomic diffusion
between adjacent steps. The physical considerations governing uncorrelated step
fluctuations occurring via random attachment/detachment events at the step edge
are discussed.Comment: 17 pages, 4 figure
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