2018
Authors
Miyandoab, FD; Canas Ferreira, JC; Grade Tavares, VM;
Publication
Journal of Mobile Multimedia
Abstract
Source routing (SR) minimum cost forwarding (MCF) – SRMCF – is a reactive, energy-efficient routing protocol proposed to improve the existent MCF methods utilized in heterogeneous wireless sensor networks (WSN). This paper presents an analytical analysis with experimental support that demonstrates the effectiveness of the proposed protocol. SRMCF stems from SR concepts and MCF methods exploited in ad hoc WSNs, where all unicast communications (between sensor nodes and the base station, or vice versa) use minimum cost paths. The protocol utilized in the present work was updated and now also handles link and node failures. Theoretical analysis and simulations show that the final protocol exhibits better throughput and energy consumption than MCF. Memory requirements for the routing table in the base station are also analyzed. Experimental results in a real scenario were obtained for implementations of both protocols, MCF and SRMCF, deployed in a small network of TelosB motes. Results show that SRMCF presents a 33% higher throughput and 24% less energy consumption than MCF. Extensive © 2019 River Publishers
2018
Authors
Derogarian, F; Ferreira, JC; Grade Tavares, VM;
Publication
J. Mobile Multimedia
Abstract
2018
Authors
Santos, PV; Alves, JC; Ferreira, JC;
Publication
U.Porto Journal of Engineering
Abstract
2018
Authors
Vaz Freitas, S; Pestana, PM; Almeida, V; Ferreira, A;
Publication
BIOMEDICAL SIGNAL PROCESSING AND CONTROL
Abstract
Objectives: To describe the results of the acoustic analysis of a database of 90 voice samples with distinct dysphonia levels, using four different - commercial and open source - software programs. Study design: Exploratory, transversal. Methods: The samples were analyzed by four different types of software programs that perform acoustical evaluation - one open source software (Praat) and three commercial ones (Multi Dimensional Voice Program - MDVP by Kay Elemetrics; VoiceStudio by Seegnal; and Dr. Speech by Tiger Electronics) - for comparison among the most commonly used acoustic measures (frequency, perturbation and noise measures). Results: There is a moderate to strong,correlation, positive and statistically significant among the software programs. The mean FO is not statistically different among the used applications. The other acoustic measures revealed statistically significant differences. Conclusion: Even though it is easier to access software programs and there are numerous proposals for acoustic measures, not all of them are statistically representative nor have numeric semblance among the different applications.
2018
Authors
Ferreira, AJ;
Publication
145th Audio Engineering Society International Convention, AES 2018
Abstract
Magnitude-oriented approaches dominate the voice analysis front-ends of most current technologies addressing e.g. speaker identification, speech coding/compression, voice reconstruction and re-synthesis. A popular technique is all-pole vocal tract modeling. The phase response of all-pole models is known to be non-linear and highly dependent on the magnitude frequency response. In this paper, we use a shift-invariant phase-related feature that is estimated from signal harmonics in order to study the impact of all-pole models on the phase structure of voiced sounds. We relate that impact to the phase structure that is found in natural voiced sounds to conclude on the physiological validity of the group delay of all-pole vocal tract modeling. Our findings emphasize that harmonic phase models are idiosyncratic, and this is important in speaker identification, and in fostering the quality and naturalness of synthetic and reconstructed speech. © 2018 KASHYAP.
2018
Authors
Ferreira, A;
Publication
ICETE 2018 - Proceedings of the 15th International Joint Conference on e-Business and Telecommunications
Abstract
In this paper we report on a number of speaker identification experiments that assume a phonetic-oriented segmentation scheme exists such as to motivate the extraction of psychoacoustically-motivated phase and pitch related features. MFCC features are also considered for benchmarking. An emphasis is given to an innovative shift-invariant phase-related feature that is closely linked to the glottal source. A very simple statistical modeling is proposed and adapted in order to highlight the relative discrimination capabilities of different feature types. Results are presented for individual features and a discussion is also developed regarding possibilities of fusing features at the speaker modeling stage, or fusing distances at the speaker identification stage. Copyright
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