298 research outputs found
A comparative study of austenitic structure in NiTi and Fe based shape memory alloys after severe plastic deformation
The effect of high speed high pressure torsion (HS-HPT) was studied in NiTi and FeMnSiCr SMAs, by comparison. Severe plastic deformation was performed in austenite state for both types of alloys. The alloys subjected to HS-HPT, reduced their grain size due to microstructure fragmentation by compression and torsion. The active elements were achieved being able to support variable ranges of processing parameters like force, pressure, rotation speed and time of torsion. The evolution of microstructural refinement in the samples subjected to different deformation by HS-HPT, were studied by optical and scanning electron microscopy observation and the thermal effect was reveled using differential scanning calorimetry (DSC). (C) 2015 The Authors. Published by Elsevier Ltd.publishersversionpublishe
INTELLIGENT WIRELESS TECHNOLOGY USAGE EFFECT IN CONTEXT OF PHYTOSANITARY TREATMENT SPRAYING
In agriculture, pesticides and fertilizers are applied to prevent crop disease and increase plant productivity. As a result of the digitalization of agriculture, human labor is increasingly interacting with intelligent technology through robots to facilitate agricultural operations. The use of intelligent technology protects the natural ecosystem by reducing the major damage caused by the unconventional application of phytosanitary treatments resulting in a flexible, proportional spraying at precise angles, thus avoiding the generation of large amounts of chemicals. This paper presents a short review about the state of the art of wireless sensors networks and how together with robotics can be applied in different fields of agriculture through the prism of sprayers that include a detection system and a wireless controlled spraye
Topological Graph Polynomials in Colored Group Field Theory
In this paper we analyze the open Feynman graphs of the Colored Group Field
Theory introduced in [arXiv:0907.2582]. We define the boundary graph
\cG_{\partial} of an open graph \cG and prove it is a cellular complex.
Using this structure we generalize the topological (Bollobas-Riordan) Tutte
polynomials associated to (ribbon) graphs to topological polynomials adapted to
Colored Group Field Theory graphs in arbitrary dimension
Bubbles and jackets: new scaling bounds in topological group field theories
We use a reformulation of topological group field theories in 3 and 4
dimensions in terms of variables associated to vertices, in 3d, and edges, in
4d, to obtain new scaling bounds for their Feynman amplitudes. In both 3 and 4
dimensions, we obtain a bubble bound proving the suppression of singular
topologies with respect to the first terms in the perturbative expansion (in
the cut-off). We also prove a new, stronger jacket bound than the one currently
available in the literature. We expect these results to be relevant for other
tensorial field theories of this type, as well as for group field theory models
for 4d quantum gravity.Comment: v2: Minor modifications to match published versio
Asymptotes in SU(2) Recoupling Theory: Wigner Matrices, Symbols, and Character Localization
In this paper we employ a novel technique combining the Euler Maclaurin
formula with the saddle point approximation method to obtain the asymptotic
behavior (in the limit of large representation index ) of generic Wigner
matrix elements . We use this result to derive asymptotic
formulae for the character of an SU(2) group element and for
Wigner's symbol. Surprisingly, given that we perform five successive
layers of approximations, the asymptotic formula we obtain for is
in fact exact. This result provides a non trivial example of a
Duistermaat-Heckman like localization property for discrete sums.Comment: 36 pages, 3 figure
Vacuum configurations for renormalizable non-commutative scalar models
In this paper we find non-trivial vacuum states for the renormalizable
non-commutative model. An associated linear sigma model is then
considered. We further investigate the corresponding spontaneous symmetry
breaking.Comment: 17 page
Random volumes from matrices
We propose a class of models which generate three-dimensional random volumes,
where each configuration consists of triangles glued together along multiple
hinges. The models have matrices as the dynamical variables and are
characterized by semisimple associative algebras A. Although most of the
diagrams represent configurations which are not manifolds, we show that the set
of possible diagrams can be drastically reduced such that only (and all of the)
three-dimensional manifolds with tetrahedral decompositions appear, by
introducing a color structure and taking an appropriate large N limit. We
examine the analytic properties when A is a matrix ring or a group ring, and
show that the models with matrix ring have a novel strong-weak duality which
interchanges the roles of triangles and hinges. We also give a brief comment on
the relationship of our models with the colored tensor models.Comment: 33 pages, 31 figures. Typos correcte
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