834 research outputs found
Multivariate manifold-valued curve regression in time
Fr\'echet global regression is extended to the context of bivariate curve
stochastic processes with values in a Riemannian manifold. The proposed
regression predictor arises as a reformulation of the standard least-squares
parametric linear predictor in terms of a weighted Fr\'echet functional mean.
Specifically, in our context, in this reformulation, the Euclidean distance is
replaced by the integrated quadratic geodesic distance. The regression
predictor is then obtained from the weighted Fr\'echet curve mean, lying in the
time-varying geodesic submanifold, generated by the regressor process
components involved in the time correlation range. The regularized Fr\'echet
weights are computed in the time-varying tangent spaces. The uniform
weak-consistency of the regression predictor is proved. Model selection is also
addressed. A simulation study is undertaken to illustrate the performance of
the spherical curve variable selection algorithm proposed in a multivariate
framework.Comment: 24 pages, 8 Figure
Combining the Burrows-Wheeler Transform and RCM-LDGM Codes for the Transmission of Sources with Memory at High Spectral Efficiencies
In this paper, we look at the problem of implementing high-throughput Joint SourceChannel (JSC) coding schemes for the transmission of binary sources with memory over AWGN channels. The sources are modeled either by a Markov chain (MC) or a hidden Markov model (HMM). We propose a coding scheme based on the Burrows-Wheeler Transform (BWT) and the parallel concatenation of Rate-Compatible Modulation and Low-Density Generator Matrix (RCM-LDGM) codes. The proposed scheme uses the BWT to convert the original source with memory into a set of independent non-uniform Discrete Memoryless (DMS) binary sources, which are then separately encoded, with optimal rates, using RCM-LDGM codes
On the Performance of Interleavers for Quantum Turbo Codes
Quantum turbo codes (QTC) have shown excellent error correction capabilities in the setting of quantum communication, achieving a performance less than 1 dB away from their corresponding hashing bounds. Existing QTCs have been constructed using uniform random interleavers. However, interleaver design plays an important role in the optimization of classical turbo codes. Consequently, inspired by the widely used classical-to-quantum isomorphism, this paper studies the integration of classical interleaving design methods into the paradigm of quantum turbo coding. Simulations results demonstrate that error floors in QTCs can be lowered significantly, while decreasing memory consumption, by proper interleaving design without increasing the overall decoding complexity of the system
Affine convex body semigroups
In this paper we present a new kind of semigroups called convex body
semigroups which are generated by convex bodies of R^k. They generalize to
arbitrary dimension the concept of proportionally modular numerical semigroup
of [7]. Several properties of these semigroups are proven. Affine convex body
semigroups obtained from circles and polygons of R^2 are characterized. The
algorithms for computing minimal system of generators of these semigroups are
given. We provide the implementation of some of them
Research about the pozzolanic activity of waste materials from calcined clay
[EN]To recycle and reutilise waste materials and find definite applications for their use, it is necessary to have a deep
knowledge of them. The aim of this study is to study the possibility of using
waste materials from calcined clay, actually ceramic tile, once crushed and grounded, as pozzolanic material. For this purpose, different tests are carried out in order to
establish the pozzolanic activity of this material. At the same time, these results are compared to those of other industrial
by-products, fly ash and silica fume, which are pozzolanic materials usually employed to elaborate mortars and concretes.[ES] Para llevar a cabo labores encaminadas al reciclado y revalorización de residuos es necesario un conocimiento profundo de los mismos, de forma que se busquen aplicaciones
concretas de uso. El objetivo de este estudio es investigar la posibilidad de
utilizar materiales de desecho procedentes de arcilla cocida, concretamente teja cerámica, una vez triturada y
molida, como puzolana. Para ello, se efectúan diferentes ensayos dirigidos a establecer la actividad puzolanica del
material. A su vez, estos resultados son comparados con otros residuos industriales, ceniza volante y humo de sílice,
habituales en la elaboración de morteros y hormigones.Peer reviewe
Brand’s communications in Covid-19. Social role during and after lockdown
The paper aims to identify the narrative communicative resources and messages spread by brands within the background of a global pandemic. This study compares two samples of advertising spots broadcast in Spain: one during the COVID-19 lockdown period and the other selected from the last de-escalation phase of the health crisis. A content analysis of a compendium of 125 commercials was proposed. The main finding is the social function adopted during lockdown in order to encourage the population with positive and resilient messages while during the de-escalation the brands recover their traditional commercial role and, do not even reflect reality with the persistence of the outbreak in the images and discourse. In fact, it showed a first phase focused on branding and a second phase when the population was urged to consume. The Covid-19 pandemic has shown a clear need for brands to adapt to an environment that has dramatically changed overnight. Practical Implications The paper includes implications for brands for sharing common support for emotional and psychological well-being in health crisis. This social function could improve their reputation and positioning globally.This work was supported by Junta de Andalucía Programme PAIDI under grant number PY20_00407 (Junta de Andalucía/Universidad de Málaga) and Funding for Open Access Charge: Universidad de Málaga /CBUA
Recursos fitogenéticos: bases para un futuro resiliente al clima y libre de hambre en el Caribe
En toda la región Caribe, el cambio climático no solamente planteará desafíos sino también una amplia gama
de oportunidades, que ofrecen mayor importancia a la riqueza de recursos fitogenéticos de la región.
Materializar el potencial de estos recursos para contribuir a garantizar la seguridad alimentaria y crear sistemas
agrícolas más resilientes frente al cambio climático requerirá de una mayor cooperación regional. Los objetivos
centrales de esta cooperación deberán ser: desarrollar intervenciones oportunas en las fronteras nacionales que
mejoren la colecta, conservación y el intercambio de los recursos fitogenéticos
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