DTSC - GPM - Artículos de Revistashttp://hdl.handle.net/10016/23152016-12-09T19:19:27Z2016-12-09T19:19:27ZThe spectra of reducible matrices over complete commutative idempotent semifields and their spectral latticesValverde-Albacete, Francisco J.Peláez-Moreno, Carmenhttp://hdl.handle.net/10016/236432016-11-04T13:15:12Z2016-03-03T00:00:00ZThe spectra of reducible matrices over complete commutative idempotent semifields and their spectral lattices
Valverde-Albacete, Francisco J.; Peláez-Moreno, Carmen
Previous work has shown a relation between L-valued extensions of Formal Concept Analysis and the spectra of some matrices related to L-valued contexts. To clarify this relation, we investigated elsewhere the nature of the spectra of irreducible matrices over idempotent semifields in the framework of dioids, naturally ordered semirings, that encompass several of those extensions. This initial work already showed many differences with respect to their counterparts over incomplete idempotent semifields, in what concerns the definition of the spectrum and the eigenvectors. Considering special sets of eigenvectors also brought out complete lattices in the picture and we argue that such structure may be more important than standard eigenspace structure for matrices over completed idempotent semifields. In this paper, we complete that investigation in the sense that we consider the spectra of reducible matrices over completed idempotent semifields and dioids, giving, as a result, a constructive solution to the all-eigenvectors problem in this setting. This solution shows that the relation of complete lattices to eigenspaces is even tighter than suspected.
2016-03-03T00:00:00ZMorphologically filtered power-normalized cochleograms as robust, biologically inspired features for ASRCalle-Silos, Fernando de laValverde-Albacete, Francisco J.Gallardo-Antolín, AscensiónPeláez-Moreno, Carmenhttp://hdl.handle.net/10016/217102016-06-16T02:12:21Z2015-11-01T00:00:00ZMorphologically filtered power-normalized cochleograms as robust, biologically inspired features for ASR
Calle-Silos, Fernando de la; Valverde-Albacete, Francisco J.; Gallardo-Antolín, Ascensión; Peláez-Moreno, Carmen
In this paper, we present advances in the modeling of the masking behavior of the human auditory system (HAS) to enhance the robustness of the feature extraction stage in automatic speech recognition (ASR). The solution adopted is based on a nonlinear filtering of a spectro-temporal representation applied simultaneously to both frequency and time domains-as if it were an image-using mathematical morphology operations. A particularly important component of this architecture is the so-called structuring element (SE) that in the present contribution is designed as a single three-dimensional pattern using physiological facts, in such a way that closely resembles the masking phenomena taking place in the cochlea. A proper choice of spectro-temporal representation lends validity to the model throughout the whole frequency spectrum and intensity spans assuming the variability of the masking properties of the HAS in these two domains. The best results were achieved with the representation introduced as part of the power normalized cepstral coefficients (PNCC) together with a spectral subtraction step. This method has been tested on Aurora 2, Wall Street Journal and ISOLET databases including both classical hidden Markov model (HMM) and hybrid artificial neural networks (ANN)-HMM back-ends. In these, the proposed front-end analysis provides substantial and significant improvements compared to baseline techniques: up to 39.5% relative improvement compared to MFCC, and 18.7% compared to PNCC in the Aurora 2 database.
2015-11-01T00:00:00ZTwo-level sliding-window VBR control algorithm for video on demand streamingFrutos-López, Manuel deGonzález de Suso, José LuisSanz-Rodríguez, SergioPeláez-Moreno, CarmenDíaz-de-María, Fernandohttp://hdl.handle.net/10016/215542016-06-16T01:41:52Z2015-08-01T00:00:00ZTwo-level sliding-window VBR control algorithm for video on demand streaming
Frutos-López, Manuel de; González de Suso, José Luis; Sanz-Rodríguez, Sergio; Peláez-Moreno, Carmen; Díaz-de-María, Fernando
A two-level variable bit rate (VBR) control algorithm for hierarchical video coding, specifically tailored for the new High Efficiency Video Coding (HEVC) standard, is presented here. A long-term level monitors the current bit count along a sliding window of a few seconds, comprising several intra-periods (IPs) and shifted on an IP basis. This long-term view allows the accommodation of the naturally occurring rate variations at a slow pace, avoiding the annoying sharp quality changes commonly appearing when non-sliding window approaches are used. The bit excesses or defects observed at this level are evenly delivered to a short-term level mechanism that establishes target bit budgets for a narrower sliding window covering a single IP and shifting on a frame basis. At this level, an adequate quantization parameter is estimated to comply with the designated target bit rate. Recommended test conditions as well as two few minutes long video sequences with scene cuts have been used for the assessment of the proposed VBR controller. Comparisons with a state-of-the-art rate control algorithm have produced good results in terms of quality consistency, in exchange for moderate rate-distortion performance losses.
2015-08-01T00:00:00ZEffect of an external electric field on the propagation velocity of premixed flamesSánchez-Sanz, MarioMurphy, Daniel C.Fernández Pello, Carloshttp://hdl.handle.net/10016/215382016-06-26T22:00:06Z2014-06-25T00:00:00ZEffect of an external electric field on the propagation velocity of premixed flames
Sánchez-Sanz, Mario; Murphy, Daniel C.; Fernández Pello, Carlos
There have been many experimental investigations into the ability of
electric fields to enhance combustion by acting upon ion species present in flames. In
this work, we examine this phenomenon using a one-dimensional model of a lean
premixed flame under the influence of a longitudinal electric field. We expand upon
prior two-step chain-branching reaction laminar models with reactions to model the
creation and consumption of both a positively-charged radical species and free
electrons. Also included are the electromotive force in the conservation equation for ion
species and the electrostatic form of the Maxwell equations in order to resolve ion
transport by externally applied and internally induced electric fields. The numerical
solution of these equations allows us to compute changes in flame speed due to electric
fields. Further, the variation of key kinetic and transport parameters modifies the
electrical sensitivity of the flame. From changes in flame speed and reactant profiles we
are able to gain novel, valuable insight into how and why combustion can be controlled
by electric fields.
2014-06-25T00:00:00Z