52,980 research outputs found
Identifying the lights position in photometric stereo under unknown lighting
Reconstructing the 3D shape of an object from a set of images is a classical
problem in Computer Vision. Photometric stereo is one of the possible
approaches. It stands on the assumption that the object is observed from a
fixed point of view under different lighting conditions. The traditional
approach requires that the position of the light sources is accurately known.
It has been proved that the lights position can be estimated directly from the
data, when at least 6 images of the observed object are available. In this
paper, we give a Matlab implementation of the algorithm for solving the
photometric stereo problem under unknown lighting, and propose a simple
shooting technique to solve the bas-relief ambiguity.Comment: new versio
Integrated Flywheel Technology, 1983
Topics of discussion included: technology assessment of the integrated flywheel systems, potential of system concepts, identification of critical areas needing development and, to scope and define an appropriate program for coordinated activity
Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy
Stripe domains are studied in perpendicular magnetic anisotropy films
nanostructured with a periodic thickness modulation that induces the lateral
modulation of both stripe periods and inplane magnetization. The resulting
system is the 2D equivalent of a strained superlattice with properties
controlled by interfacial misfit strain within the magnetic stripe structure
and shape anisotropy. This allows us to observe, experimentally for the first
time, the continuous structural transformation of a grain boundary in this 2D
magnetic crystal in the whole angular range. The magnetization reversal process
can be tailored through the effect of misfit strain due to the coupling between
disclinations in the magnetic stripe pattern and domain walls in the in-plane
magnetization configuration
Democratic particle motion for meta-basin transitions in simple glass-formers
We use molecular dynamics computer simulations to investigate the local
motion of the particles in a supercooled simple liquid. Using the concept of
the distance matrix we find that the alpha-relaxation corresponds to a small
number of crossings from one meta-basin to a neighboring one. Each crossing is
very rapid and involves the collective motion of O(40) particles that form a
relatively compact cluster, whereas string-like motions seem not to be relevant
for these transitions. These compact clusters are thus candidates for the
cooperatively rearranging regions proposed long times ago by Adam and Gibbs.Comment: 4 pages, 4 Postscript figure
Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions
Magnetic lateral multilayers have been fabricated on weak perpendicular
magnetic anisotropy amorphous Nd-Co films in order to perform a systematic
study on the conditions for controlled nucleation of topological defects within
their magnetic stripe domain pattern. A lateral thickness modulation of period
is defined on the nanostructured samples that, in turn, induces a lateral
modulation of both magnetic stripe domain periods and average
in-plane magnetization component . Depending on lateral multilayer
period and in-plane applied field, thin and thick regions switch independently
during in-plane magnetization reversal and domain walls are created within the
in-plane magnetization configuration coupled to variable angle grain boundaries
and disclinations within the magnetic stripe domain patterns. This process is
mainly driven by the competition between rotatable anisotropy (that couples the
magnetic stripe pattern to in-plane magnetization) and in-plane shape
anisotropy induced by the periodic thickness modulation. However, as the
structural period becomes comparable to magnetic stripe period ,
the nucleation of topological defects at the interfaces between thin and thick
regions is hindered by a size effect and stripe domains in the different
thickness regions become strongly coupled.Comment: 10 pages, 7 figures, submitted to Physical Review
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