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Publicações

Publicações por CTM

2006

XCP for shared-access multi-rate media

Autores
Abrantes, F; Ricardo, M;

Publicação
ACM SIGCOMM COMPUTER COMMUNICATION REVIEW

Abstract
The eXplicit Control Protocol (XCP) was developed to overcome some of the limitations of TCP, such as low utilization in high bandwidth delay product networks, unstable throughput, large queue build-up, and limited fairness. XCP, however, requires that each queue controller in a path knows the exact capacity of its link. In shared access media, e.g. IEEE 802.11, knowing the actual capacity of the channel is a difficult task. In this paper we propose modifications to the XCP algorithm that enable the utilization of XCP even when the capacity of a link is unknown. These modifications are validated through simulation. We also present the results of a comparison between the performance of the modified XCP and TCP, where XCP controlled flows result more stable, fairness increases, and the network delay becomes lower. In addition, as the bandwidth delay product increases, XCP is able to maintain near-maximum utilization while TCP decreases utilization.

2006

A low-power oscillation based LNA BIST scheme

Autores
da Silva, JM;

Publicação
IEEE DTIS: 2006 International Conference on Design & Test of Integrated Systems in Nanoscale Technology, Proceedings

Abstract
Test stimuli generation and power consumption are two Issues that jeopardize the design of built-in self test schemes. The LNA testing approach presented herein relies on converting the amplifier Into an oscillator and on using a low-power correlator to obtain a signature from the cross-correlation between the dynan-dc power supply current and the LNA's output voltage. In test mode a high fault coverage is obtained together with a low power consumption, while avoiding an extra stimulus generator. No significant performance degradation results from the added test circuitry. Concerning the Interface with the external tester, a digital signal is required to switch between normal and test modes, as well as a low frequency line to capture the correlator DC output voltage.

2006

Institutional communication in Higher Education: virtual visits and usability

Autores
Suarez, A; Moreira, RS; Carrapatoso, E;

Publicação
ACTAS DA 1A CONFERENCIA IBERICA DE SISTEMAS E TECNOLOGIAS DE INFORMACAO, VOL II

Abstract

2006

Towards a computer-aided medical system for the aesthetic evaluation of breast cancer conservative treatment.

Autores
Cardoso, MJ; Cardoso, JS;

Publicação
BREAST CANCER RESEARCH AND TREATMENT

Abstract

2006

Automatic speaker segmentation using multiple features and distance measures: A comparison of three approaches

Autores
Kotti, M; Martins, LGPM; Benetos, E; Cardoso, JS; Kotropoulos, C;

Publicação
2006 IEEE International Conference on Multimedia and Expo - ICME 2006, Vols 1-5, Proceedings

Abstract
This paper addresses the problem of unsupervised speaker change detection. Three systems based on the Bayesian Information Criterion (BIC) are tested. The first system investigates the AudioSpectrumCentroid and the AudioWaveformEnvelope features, implements a dynamic thresholding followed by a fusion scheme, and finally applies BIC. The second method is a real-time one that uses a metric-based approach employing the line spectral pairs and the BIC to validate a potential speaker change point. The third method consists of three modules. In the first module, a measure based on second-order statistics is used; in the second module, the Euclidean distance and T-2 Hotelling statistic are applied; and in the third module, the BIC is utilized. The experiments are carried out on a dataset created by concatenating speakers from the TIMIT database, that is referred to as the TIMIT data set. A comparison between the performance of the three systems is made based on t-statistics.

2006

Classification of Ordinal Data

Autores
Cardoso, JS;

Publicação
CoRR

Abstract

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