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81.
Oscar M. Bonastre Marie-José Montpetit Pablo Cesar 《Multimedia Tools and Applications》2011,53(3):481-485
The move to IP Protocol Television (IPTV) has challenged the traditional television industry by opening the Internet to high
quality real time television content delivery. Thus it has provided an enabling set of key technologies to understand and
foster further innovations in the multimedia landscape and to create dynamics in the TV value chain. This editorial provides
a brief overview of this special issue. It begins with a short introduction to IPTV Technology and then summarizes the main
contributions of the selected papers for this special issue, highlighting their salient features and novel results. 相似文献
82.
Virginia Francisco Pablo Gervás Federico Peinado 《Knowledge and Information Systems》2010,25(3):421-443
With the advent of affective computing, the task of adequately identifying, representing and processing the emotional connotations
of text has acquired importance. Two problems facing this task are addressed in this paper: the composition of sentence emotion
from word emotion, and a representation of emotion that allows easy conversion between existing computational representations.
The emotion of a sentence of text should be derived by composition of the emotions of the words in the sentence, but no method
has been proposed so far to model this compositionality. Of the various existing approaches for representing emotions, some
are better suited for some problems and some for others, but there is no easy way of converting from one to another. This
paper presents a system that addresses these two problems by reasoning with two ontologies implemented with Semantic Web technologies:
one designed to represent word dependency relations within a sentence, and one designed to represent emotions. The ontology
of word dependency relies on roles to represent the way emotional contributions project over word dependencies. By applying
automated classification of mark-up results in terms of the emotion ontology the system can interpret unrestricted input in
terms of a restricted set of concepts for which particular rules are provided. The rules applied at the end of the process
provide configuration parameters for a system for emotional voice synthesis. 相似文献
83.
Pablo Quintía Roberto Iglesias Miguel A. Rodríguez Carlos V. Regueiro 《Robotics and Autonomous Systems》2010,58(12):1306-1315
One of the main problems of robots is the lack of adaptability and the need for adjustment every time the robot changes its working place. To solve this, we propose a learning approach for mobile robots using a reinforcement-based strategy and a dynamic sensor-state mapping. This strategy, practically parameterless, minimises the adjustments needed when the robot operates in a different environment or performs a different task.Our system will simultaneously learn the state space and the action to execute on each state. The learning algorithm will attempt to maximise the time before a robot failure in order to obtain a control policy suited to the desired behaviour, thus providing a more interpretable learning process. The state representation will be created dynamically, starting with an empty state space and adding new states as the robot finds new situations that has not seen before. A dynamic creation of the state representation will avoid the classic, error-prone and cyclic process of designing and testing an ad hoc representation. We performed an exhaustive study of our approach, comparing it with other classic strategies. Unexpectedly, learning both perception and action does not increase the learning time. 相似文献
84.
Ricardo V. de Oliveira Rodrigo A. Ramos Newton G. Bretas 《Control Engineering Practice》2010,18(1):45-54
The main objective of this paper is to relieve the power system engineers from the burden of the complex and time-consuming process of power system stabilizer (PSS) tuning. To achieve this goal, the paper proposes an automatic process for computerized tuning of PSSs, which is based on an iterative process that uses a linear matrix inequality (LMI) solver to find the PSS parameters. It is shown in the paper that PSS tuning can be written as a search problem over a non-convex feasible set. The proposed algorithm solves this feasibility problem using an iterative LMI approach and a suitable initial condition, corresponding to a PSS designed for nominal operating conditions only (which is a quite simple task, since the required phase compensation is uniquely defined). Some knowledge about the PSS tuning is also incorporated in the algorithm through the specification of bounds defining the allowable PSS parameters. The application of the proposed algorithm to a benchmark test system and the nonlinear simulation of the resulting closed-loop models demonstrate the efficiency of this algorithm. 相似文献
85.
The discrete ordered median location model is a powerful tool in modeling classic and alternative location problems that have been applied with success to a large variety of discrete location problems. Nevertheless, although hub location models have been analyzed from the sum, maximum and coverage point of views, as far as we know, they have never been considered under an alternative unifying point of view. In this paper we consider new formulations, based on the ordered median objective function, for hub location problems with new distribution patterns induced by the different users’ roles within the supply chain network. This approach introduces some penalty factors associated with the position of an allocation cost with respect to the sorted sequence of these costs. First we present basic formulations for this problem, and then develop stronger formulations by exploiting properties of the model. The performance of all these formulations is compared by means of a computational analysis. 相似文献
86.
Jonathan Pietarila Graham Darryl D. Holm Pablo Mininni Annick Pouquet 《Journal of scientific computing》2011,49(1):21-34
The subfilter-scale (SFS) physics of regularization models are investigated to understand the regularizations’ performance
as SFS models. Suppression of spectrally local SFS interactions and conservation of small-scale circulation in the Lagrangian-averaged
Navier-Stokes α-model (LANS-α) is found to lead to the formation of rigid bodies. These contaminate the superfilter-scale energy spectrum with a scaling
that approaches k
+1 as the SFS spectra is resolved. The Clark-α and Leray-α models, truncations of LANS-α, do not conserve small-scale circulation and do not develop rigid bodies. LANS-α, however, is closest to Navier-Stokes in intermittency properties. All three models are found to be stable at high Reynolds
number. Differences between L
2 and H
1 norm models are clarified. For magnetohydrodynamics (MHD), the presence of the Lorentz force as a source (or sink) for circulation
and as a facilitator of both spectrally nonlocal large to small scale interactions as well as local SFS interactions prevents
the formation of rigid bodies in Lagrangian-averaged MHD (LAMHD-α). LAMHD-α performs well as a predictor of superfilter-scale energy spectra and of intermittent current sheets at high Reynolds numbers.
It may prove generally applicable as a MHD-LES. 相似文献
87.
Pablo Irarrazaval Carlos Lizama Vicente Parot Carlos Sing-Long Cristian Tejos 《Computers & Mathematics with Applications》2011,62(3):1576-1590
The fractional Fourier transform (FrFT) is revisited in the framework of strongly continuous periodic semigroups to restate known results and to explore new properties of the FrFT. We then show how the FrFT can be used to reconstruct Magnetic Resonance (MR) images acquired under the presence of quadratic field inhomogeneity. Particularly, we prove that the order of the FrFT is a measure of the distortion in the reconstructed signal. Moreover, we give a dynamic interpretation to the order as time evolution of a function. We also introduce the notion of ρ-α space as an extension of the Fourier or k-space in MR, and we use it to study the distortions introduced in two common MR acquisition strategies. We formulate the reconstruction problem in the context of the FrFT and show how the semigroup theory allows us to find new reconstruction formulas for discrete sampled signals. Finally, the results are supplemented with numerical examples that show how it performs in a standard 1D MR signal reconstruction. 相似文献
88.
O. PostolacheAuthor Vitae H. Geirinhas Ramos Author VitaeA. Lopes Ribeiro Author Vitae 《Computer Standards & Interfaces》2011,33(2):191-200
This work presents an eddy-current testing system based on a giant magnetoresistive (GMR) sensing device. Non-destructive tests in aluminum plates are applied in order to extract information about possible defects: cracks, holes and other mechanical damages. Eddy-current testing (ECT) presents major benefits such as low cost, high checking speed, robustness and high sensitivity to large classes of defects. Coil based architecture probes or coil-magnetoresistive probes are usually used in ECT. In our application the GMR sensor is used to detect a magnetic field component parallel to a plate surface, when an excitation field perpendicular to the plate is imposed. A neural network processing architecture, including a multilayer perceptron and a competitive neural network, is used to classify defects using the output amplitude of the eddy-current probe (ECP) and its operation frequency. The crack detection, classification and estimation of the geometrical characteristics, for different classes of defects, are described in the paper. 相似文献
89.
Pablo Cascón Andrés Ortiz Julio Ortega Antonio F. Díaz Ignacio Rojas 《The Journal of supercomputing》2011,58(3):302-313
Hosts with several, possibly heterogeneous and/or multicore, processors provide new challenges and opportunities to accelerate
applications with high communications bandwidth requirements. Many opportunities to scale these network applications with the increase in the link bandwidths are related to the exploitation of the available parallelism provided by the presence
of several processing cores in the servers, not only for computing the workload of the user application but also for decreasing
the overhead associated to the network interface and the system software. 相似文献
90.
Ney Sodr Pablo Guillermo Gonzales-Ormeo Helena Maria Petrilli Cludio Geraldo Schn 《Calphad》2009,33(3):576-583
The metastable phase diagram of the BCC-based ordering equilibria in the Fe–Al–Mo system has been calculated via a truncated cluster expansion, through the combination of Full-Potential-Linear augmented Plane Wave (FP-LAPW) electronic structure calculations and of Cluster Variation Method (CVM) thermodynamic calculations in the irregular tetrahedron approximation. Four isothermal sections at 1750 K, 2000 K, 2250 K and 2500 K are calculated and correlated with recently published experimental data on the system. The results confirm that the critical temperature for the order–disorder equilibrium between Fe3Al–D03 and FeAl–B2 is increased by Mo additions, while the critical temperature for the FeAl–B2/A2 equilibrium is kept approximately invariant with increasing Mo contents. The stabilization of the Al-rich A2 phase in equilibrium with overstoichiometric B2–(Fe,Mo)Al is also consistent with the attribution of the A2 structure to the τ2 phase, stable at high temperatures in overstoichiometric B2–FeAl. 相似文献