Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

Publications by CTM

2011

Microtiming Patterns and Interactions with Musical Properties in Samba Music

Authors
Naveda, L; Gouyon, F; Guedes, C; Leman, M;

Publication
JOURNAL OF NEW MUSIC RESEARCH

Abstract
In this study, we focus on the interaction between microtiming patterns and several musical properties: intensity, meter and spectral characteristics. The data-set of 106 musical audio excerpts is processed by means of an auditory model and then divided into several spectral regions and metric levels. The resulting segments are described in terms of their musical properties, over which patterns of peak positions and their intensities are sought. A clustering algorithm is used to systematize the process of pattern detection. The results confirm previously reported anticipations of the third and fourth semiquavers in a beat. We also argue that these patterns of microtiming deviations interact with different profiles of intensities that change according to the metrical structure and spectral characteristics. In particular, we suggest two new findings: (i) a small delay of microtiming positions at the lower end of the spectrum on the first semiquaver of each beat and (ii) systematic forms of accelerando and ritardando at a microtiming level covering two-beat and four-beat phrases. The results demonstrate the importance of multidimensional interactions with timing aspects of music. However, more research is needed in order to find proper representations for rhythm and microtiming aspects in such contexts.

2011

Development of a BCCT Quantitative 3D Evaluation System through Low-Cost Solutions

Authors
Oliveira, HP; Patete, P; Baroni, G; Cardoso, JS;

Publication
Proceedings of the 2nd International Conference on 3D Body Scanning Technologies, Lugano, Switzerland, 25-26 October 2011

Abstract

2011

Stability of traveling pulses of cubic-quintic complex Ginzburg-Landau equation including intrapulse Raman scattering

Authors
Facao, M; Carvalho, MI;

Publication
PHYSICS LETTERS A

Abstract
The complex cubic-quintic Ginzburg-Landau equation (CGLE) admits a special type of solutions called eruption solitons. Recently, the eruptions were shown to diminish or even disappear if a term of intrapulse Raman scattering (IRS) is added, in which case, self-similar traveling pulses exist. We perform a linear stability analysis of these pulses that shows that the unstable double eigenvalues of the erupting solutions split up under the effect of IRS and, following a different trajectory, they move on to the stable half-plane. The eigenfunctions characteristics explain some eruptions features. Nevertheless, for some CGLE parameters, the IRS cannot cancel the eruptions, since pulses do not propagate for the required IRS strength.

2011

WiFIX+: A multicast solution for 802.11-based Wireless Mesh Networks

Authors
Campos, R; Oliveira, C; Ruela, J;

Publication
2011 8th International Conference on Wireless On-Demand Network Systems and Services, WONS 2011

Abstract
IEEE 802.11 is currently one of the main wireless technologies enabling ubiquitous Internet access. With the growing demand for wireless Internet access and the limited 802.11 radio range, 802.11-based Wireless Mesh Networks have been proposed as a flexible and cost-effective solution to extend the radio coverage of existing network infrastructures. Many solutions have been proposed to create Wireless Mesh Networks automatically. However, they are either too complex or deal with multicast traffic inefficiently using pure flooding. We propose a simple and efficient solution, called WiFIX+, to forward multicast traffic over 802.11-based Wireless Mesh Networks. It is based on WiFIX, an existing solution targeted at unicast traffic and extends it with new mechanisms. WiFIX+ was implemented and evaluated in a laboratorial test-bed. The experimental results obtained show that it outperforms IEEE 802.11s, the reference solution for 802.11-based Wireless Mesh Networks, as far as data throughput, delay, and packet loss are concerned. © 2010 IEEE.

2011

Non-contact Pulse Wave Velocity Assessment Using Optical Methods

Authors
Pereira, T; Cabeleira, M; Matos, P; Borges, E; Almeida, V; Pereira, HC; Cardoso, J; Correia, CMBA;

Publication
Biomedical Engineering Systems and Technologies - 4th International Joint Conference, BIOSTEC 2011, Rome, Italy, January 26-29, 2011, Revised Selected Papers

Abstract
The clinical relevance of pulse wave velocity (PWV), as an indicator of cardiac risk associated to arterial stiffness, has gained clinical relevance over the last years. Optic sensors are an attractive instrumental solution for this type of measurement due to their truly non-contact operation capability, which has the potential of an interference free measurement. The nature of the optically originated signals, however, poses new challenges to the designer, either at the probe design level as at the signal processing required to extract the timing information that yields PWV. In this work we describe the construction of two prototype optical probes and discuss their evaluation using three algorithms for pulse transit time (PTT) evaluation. Results, obtained in a dedicated test bench, that is also described, demonstrate the possibility of measuring pulse transit times as short as 1ms with less than 1% error. © Springer-Verlag Berlin Heidelberg 2013.

2011

Signal analysis in a new optical pulse waveform profiler for cardiovascular applications

Authors
Pereira, T; Oliveira, T; Cabeleira, M; Matos, P; Pereira, HC; Almeida, V; Borges, E; Santos, H; Pereira, T; Cardoso, J; Correia, C;

Publication
Proceedings of the IASTED International Conference on Signal and Image Processing and Applications, SIPA 2011

Abstract
Sub-millimetre distension waveforms (0.7 mm, max) are assessed using two new optical probes. The probes differ on the type of photo-detector used: planar photodiodes (PPD), in one case, and avalanche photodiodes (APD), in the other. Performance of the probes is evaluated in an especially developed test setup and in vivo, at the carotid site of humans. In the latter case, distension (associated to the pressure wave generated by the left ventricle contraction that propagates through the arterial system) carries clinically relevant information that can be extracted if, as will be shown, the waveforms are accurate and have enough resolution. An ultrasound image system, Vivid" e, was used as source of reference data for comparison. Along with the probes, a set of software routines was also developed to extract artefact-free data and evaluate the error. Results from the test setup demonstrate the possibility of waveform distension measurements with less than 6% error for both optical probes in this study. In comparison with an ultrasound system, the optical sensors allow the reproduction of the arterial waveform with a higher resolution, adequate to feed feature extraction algorithms.

  • 300
  • 377