Abstract
This paper presents the Gene Fragment Competition concept that can be used with Hybrid Genetic Algorithms specially in signal and image processing. Memetic Algorithms have shown great success in real-life problems by adding local search operators to improve the quality of the already achieved "good" solutions during the evolutionary process. Nevertheless these traditional local search operators don't perform well in highly demanding evaluation processes. This stresses the need for a new semi-local non-exhaustive method. Our proposed approach sits as a tradeoff between classical Genetic Algorithms and traditional Memetic Algorithms, performing a quasi-global/quasi-local search by means of gene fragment evaluation and selection. The applicability of this hybrid Genetic Algorithm to the signal processing problem of Polyphonic Music Transcription is shown. The results obtained show the feasibility of the approach.

Abstract
In this paper, an evaluation of several methods allowing the estimation of the Harmonic-to-Noise Ratio (HNR) of sustained vowels was conducted. The HNR estimation methods are mainly based on time, spectral, and cepstral signal representations. An algorithm was implemented for each method and was tested with synthesized voice sounds in order to evaluate their accuracy. Tests were also conducted with real pathological voice sounds in order to evaluate the behaviour of the different methods under real conditions. © 2008 Division of Signal Processin.

Abstract
Vowel recognition is frequently based on Linear Prediction (LP) analysis and formant estimation techniques. However, the performance of these techniques decreases in the case of female or child speech because at high pitch frequencies (F0) the magnitude spectrum is scarcely sampled making formant estimation unreliable. In this paper we describe the implementation of a perceptually motivated concept of vowel recognition that is based on Perceptual Spectral Clusters (PSC) of harmonic partials. PSC based features were evaluated in automatic recognition tests using the Mahalanobis distance and using a data base of five natural Portuguese vowel sounds uttered by 44 speakers, 27 of whom are child speakers. LP based features and Mel-Frequency Cepstral Coefficients (MFCC) were also included in the tests as a reference. Results show that while the recognition performance of PSC features falls between that of LP based features and that of MFCC coefficients, the normalization of PSC features by F0 increases the performance and approaches that of MFCC coefficients. PSC features are not only amenable to a psychophysical interpretation (as LP based features are) but have also the potential to compete with global shape features such as MFCCs.

Abstract
Network operators have been reluctant to deploy IP multicast services mainly due to the lack of native control rover multicast groups. This lack of control does not only prevent operators from generating revenue from multicast-based services but also hinders regular network management. In this work we identified the network elements where admission control should be enforced for multicast session spawning over heterogeneous access networks. The architecture proposed uses existing AAA functionality to perform user identification and multicast session admission control. This control is made at the network layer with no protocol modifications. Three access networks were considered: xDSL, WiMAX and UMTS.

Abstract
Technological evolution is leading telecommunications toward all-IP scenarios, where multiple services are transported as IP packets. Among these services is the broadcast of video. A possible mechanism for broadcasting multiple video channels over IP is to use IP multicast, and let each client decide about the reception of a channel. The secure IP multicast specified by the IETF MSEC working group is a candidate solution for securing these broadcast services. In this paper we propose a new solution for supporting the broadcast of multiple video channels which can be accessed only by authorized users; besides, when a video channel is not visualized in the last mile its transmission is temporarily suspended, so that the cable can be used for other services such as standard Internet access.

Abstract
Communication networks have been developed based on two networking approaches: bridging and routing. The convergence to an all-Ethernet paradigm in Personal and Local Area Networks and the increasing heterogeneity found in these networks emphasizes the current and future applicability of bridging. When bridging is used, a single active spanning tree needs to be defined. A Minimum Routing Cost Tree is known to be the optimal spanning tree if the probability of communication between any pair of network nodes is the same. Given that its computation is a NP-hard problem, approximation algorithms have been proposed. We propose a new approximation Minimum Routing Cost Tree algorithm. Our algorithm has time complexity lower than the fastest known approximation algorithm and provides a spanning tree with the same routing cost in practice. In addition, it represents a better solution than the current spanning tree algorithm used in bridged networks.