14,481 research outputs found
On spectral types of semialgebraic sets
In this work we prove that a semialgebraic set is
determined (up to a semialgebraic homeomorphism) by its ring
of (continuous) semialgebraic functions while its ring of
(continuous) bounded semialgebraic functions only determines besides a
distinguished finite subset . In addition it holds that the
rings and are isomorphic if and only if
is compact. On the other hand, their respective maximal spectra
and endowed with the Zariski topology are always homeomorphic and
topologically classify a `large piece' of . The proof of this fact requires
a careful analysis of the points of the remainder associated with formal paths.Comment: 22 page
Solving the Constraints of General Relativity
I show in this letter that it is possible to solve some of the constraints of
the -ADM formalism for general relativity by using an approach similar
to the one introduced by Capovilla, Dell and Jacobson to solve the vector and
scalar constraints in the Ashtekar variables framework. I discuss the
advantages of using the ADM formalism and compare the result with similar
proposals for different Hamiltonian formulations of general relativity.Comment: 8 pages, LATEX, no figures, Preprint CGPG-94/11-
Combating catastrophic forgetting with developmental compression
Generally intelligent agents exhibit successful behavior across problems in
several settings. Endemic in approaches to realize such intelligence in
machines is catastrophic forgetting: sequential learning corrupts knowledge
obtained earlier in the sequence, or tasks antagonistically compete for system
resources. Methods for obviating catastrophic forgetting have sought to
identify and preserve features of the system necessary to solve one problem
when learning to solve another, or to enforce modularity such that minimally
overlapping sub-functions contain task specific knowledge. While successful,
both approaches scale poorly because they require larger architectures as the
number of training instances grows, causing different parts of the system to
specialize for separate subsets of the data. Here we present a method for
addressing catastrophic forgetting called developmental compression. It
exploits the mild impacts of developmental mutations to lessen adverse changes
to previously-evolved capabilities and `compresses' specialized neural networks
into a generalized one. In the absence of domain knowledge, developmental
compression produces systems that avoid overt specialization, alleviating the
need to engineer a bespoke system for every task permutation and suggesting
better scalability than existing approaches. We validate this method on a robot
control problem and hope to extend this approach to other machine learning
domains in the future
A liquid crystal analogue of the cosmic string
We consider the propagation of light in a anisotropic medium with a
topological line defect in the realm of geometrical optics. It is shown that
the effective geometry perceived by light propagating in such medium is that of
a spacial section of the cosmic string spacetime.Comment: 3 pages, 2 figures. Modern Physics Letters A, accepted for
publicatio
Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: application to Gusev Crater and Meridiani Planum
The analysis of the surface texture from the particle (grain size, shape and
internal structure) to its organization (surface roughness) provides
information on the geological processes. CRISM multi-angular observations
(varied emission angles) allow to characterize the surface scattering behavior
which depends on the composition but also the material physical properties
(e.g., grain size, shape, internal structure, the surface roughness). After an
atmospheric correction by the Multi-angle Approach for Retrieval of the Surface
Reflectance from CRISM Observations, the surface reflectances at different
geometries are analyzed by inverting the Hapke photometric model depending on
the single scattering albedo, the 2-term phase function, the macroscopic
roughness and the 2-term opposition effects. Surface photometric maps are
created to observe the spatial variations of surface scattering properties as a
function of geological units at the CRISM spatial resolution (200m/pixel). An
application at the Mars Exploration Rover (MER) landing sites located at Gusev
Crater and Meridiani Planum where orbital and in situ observations are
available, is presented. Complementary orbital observations (e.g. CRISM
spectra, THermal EMission Imaging System, High Resolution Imaging Science
Experiment images) are used for interpreting the estimated Hapke photometric
parameters in terms of physical properties. The in situ observations are used
as ground truth to validate the interpretations. Varied scattering properties
are observed inside a CRISM observation (5x10km) suggesting that the surfaces
are controlled by local geological processes (e.g. volcanic resurfacing,
aeolian and impact processes) rather than regional or global. Consistent
results with the in situ observations are observed thus validating the approach
and the use of photometry for the characterization of Martian surface physical
properties
Using choreographies to support the gamification process on the development of an application to reduce electricity costs
Building automation systems contribute to reduce electricity costs by managing distributed energy resources in an efficient way. However, a large share of consumption cannot be optimized through automation alone, since it mainly depends on human interactions. Gamification can be used as one form of changing usersâ behaviours [1], but its implementation does require assumptions on the behaviour patterns that need to
be identified, encouraged, or discouraged. To tackle this problem, we propose a framework that joins building automation solutions with gamification techniques to enable behavioural demand response.info:eu-repo/semantics/publishedVersio
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