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Publications

Publications by CTM

2017

Performance improvement of a buck converter using Kalman filtering

Authors
Pereira, A; Duarte, C; Costa, P; Gora, W;

Publication
International Journal of Power Electronics

Abstract
This paper presents a predictive current control algorithm for a synchronous buck converter using an extended Kalman filter (EKF) algorithm. The predictive approach avoids the need of current-sensing circuitry and provides insensitivity to Gaussian noise sources at the output of the buck converter, which is the same as the control loop input. The method requires a model for the buck converter, the EKF design, and current loop tuning. All these prerequisites are described in this work along with the implementation of the algorithm in a state of the art microcontroller. Simulation and experimental results show that while maintaining a good step response, the proposed method provides better results than standard methods when Gaussian noise is present at the output voltage. © 2017 Inderscience Enterprises Ltd.

2017

Building an End User focused THz based Ultra High Bandwidth Wireless Access Network: The TERAPOD Approach

Authors
Davy, A; Pessoa, L; Renaud, C; Wasige, E; Naftaly, M; Kuerner, T; George, G; Cojocari, O; Mahony, NO; Porcel, MAG;

Publication
2017 9TH INTERNATIONAL CONGRESS ON ULTRA MODERN TELECOMMUNICATIONS AND CONTROL SYSTEMS AND WORKSHOPS (ICUMT)

Abstract
The TERAPOD project aims to investigate and demonstrate the feasibility of ultra high bandwidth wireless access networks operating in the Terahertz (THz) band. The proposed TERAPOD THz communication system will be developed, driven by end user usage scenario requirements and will be demonstrated within a first adopter operational setting of a Data Centre. In this article, we define the full communications stack approach that will be taken in TERAPOD, highlighting the specific challenges and aimed innovations that are targeted.

2017

Underwater visible light communications, channel modeling and system design

Authors
Khalighi, MA; Gabriel, CJ; Pessoa, LM; Silva, B;

Publication
Visible Light Communications: Theory and Applications

Abstract
Demands for underwater communication systems are increasing due to the ongoing expansion of human activities in underwater environments such as environmental monitoring, underwater exploration, offshore oil field exploration and monitoring, port security, and tactical surveillance. As such, there is a serious requirement to improve the performance of underwater communication systems in order to effectively use the equipment and the resources. The high cost, lack of flexibility, and operational disadvantages of wireline (particularly optical fiber) systems to provide real-time communication in underwater applications become restrictive for many cases. This triggers the growing demand for underwater wireless links. Acoustic communications suffer from a very small available bandwidth, very low celerity, and large latencies due to the low propagation speed. Underwater wireless optical communications (UWOC) which are able to achieve data rates of hundreds of Mbps (even up to Gbps) for short ranges, typically several tens of meters, appear as an attractive alternative or complementary solution to long-range acoustic communications. In fact, water is relatively transparent to light in the visible band of the spectrum and absorption takes its minimum value in the blue-green spectral range (450 nm-550 nm) [1,2]. Thanks to the ability of providing unprecedentedly high-rate data transmission, the UWOC technology enables the establishment of high-speed and reliable links for underwater missions employing robotics or autonomous underwater vehicles (AUVs), for instance. In addition, it is highly energy efficient, compared to the traditional technique of acoustic communication, and also has much less impact on marine animal life (see Figure 11.1) [3,4]. In particular, it is harmless to the cetaceans and coral. © 2017 by Taylor & Francis Group, LLC.

2017

Application-driven Wireless Sensor Networks

Authors
Bruno Filipe Lopes Garcia Marques;

Publication

Abstract

2017

AUTOMATIC MUSICAL KEY ESTIMATION WITH ADAPTIVE MODE BIAS

Authors
Bernardes, G; Davies, MEP; Guedes, C;

Publication
2017 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP)

Abstract
In this paper we present the INESC Key Detection (IKD) system which incorporates a novel method for dynamically biasing key mode estimation using the spatial displacement of beat-synchronous Tonal Interval Vectors (TIVs). We evaluate the performance of the IKD system at finding the global key on three annotated audio datasets and using three key-defining profiles. Results demonstrate the effectiveness of the mode bias in favoring either the major or minor mode, thus allowing users to fine tune this variable to improve correct key estimates on style-specific music datasets or to balance predictions across key modes on unknown input sources.

2017

A Hierarchical Harmonic Mixing Method

Authors
Bernardes, G; Davies, MEP; Guedes, C;

Publication
CMMR

Abstract
We present a hierarchical harmonic mixing method for assisting users in the process of music mashup creation. Our main contributions are metrics for computing the harmonic compatibility between musical audio tracks at small- and large-scale structural levels, which combine and reassess existing perceptual relatedness (i.e., chroma vector similarity and key affinity) and dissonance-based approaches. Underpinning our harmonic compatibility metrics are harmonic indicators from the perceptually-motivated Tonal Interval Space, which we adapt to describe musical audio. An interactive visualization shows hierarchical harmonic compatibility viewpoints across all tracks in a large musical audio collection. An evaluation of our harmonic mixing method shows our adaption of the Tonal Interval Space robustly describes harmonic attributes of musical instrument sounds irrespective of timbral differences and demonstrates that the harmonic compatibility metrics comply with the principles embodied in Western tonal harmony to a greater extent than previous approaches.

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