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Publications

Publications by José Machado da Silva

2014

A Transceiver for E-Textile Body-Area-Networks

Authors
Carvalho, JG; da Silva, JM;

Publication
2014 IEEE INTERNATIONAL SYMPOSIUM ON MEDICAL MEASUREMENTS AND APPLICATIONS (MEMEA)

Abstract
A transceiver for single-line communication among sensor nodes of a body-area network is presented. It is meant to operate on a mesh like network where nodes are interconnected by two conducting-textile lines, which provide both power and communication features. The textile conductors are sewn directly to the garment in order to enhance user's mobility and comfort. For the same reason, a single battery placed in a central processing module is used to supply all sensor nodes. A low-dropout voltage regulator supplied from the transmission-line via a low pass filter ensures in each node the respective 3 V DC power supply. Power-line-communication is performed using a binary phase shift keying modulation process over a non-zero direct current line voltage at a 10 Mbps rate. The transceiver includes also line-fault testing to detect hazards which are likely to occur due to the stress applied to the conductive yarns.

2013

A Stent-Graft Endoleakage Monitor: Telemetry System Based on Inductive-Coupling Transmission for Implantable Pressure Sensors

Authors
Oliveira, C; Almeida, N; da Silva, JM;

Publication
2013 IEEE 3RD PORTUGUESE MEETING IN BIOENGINEERING (ENBENG)

Abstract
A direct arterial pressure monitoring system for post EVAR procedure based on inductive-coupling is presented which avoids the need for more complex biomedical imaging systems. Post stent-graft implantation complications, such as endoleaks, can be detected with capacitive pressure sensors placed in the stent-graft and monitored externally after the measurement of the oscillation frequency of a LC resonant circuit created by sensors and inductive coupling. Several measurements were performed in order to characterize the system and compare the results with the expected values based on theoretical models. Different measurements were carried-out with the purpose of evaluating the system's frequency detection accuracy throughout the working bandwidth and varying distances between the reader and the sensors. Both air and a phantom with electrical characteristics similar to the human body were used between the reader and the sensors antennas in order to evaluate the influence of the transmission medium. It is shown that in both cases the system is capable of detecting the oscillation frequencies, even in the case a cluster of sensors is used.

2015

Smart Orchard Irrigation System

Authors
Siqueira, JD; da Silva, JM; do Paco, TA;

Publication
2015 Conference on Design of Circuits and Integrated Systems (DCIS)

Abstract
The present work addresses the development of a smart orchard irrigation system (SOIS) that performs the estimation of orchard evapotranspiration and the estimation of the soil salinization risk. Measurements of heat transfer are made to compute tree transpiration rate and soil water evaporation. The soil electrical conductivity is measured to compute the soil salinization risk. An inferential fuzzy algorithm is used to process data. This paper describes the physical principles underlining these estimations, the architecture of the data acquisition interface, and the construction and characterization of the probes used to perform the temperature measurements. The preliminary results shown here address the experimental evaluation of the performance of the probes inserted in the trees. Relative measurements with a precision of 0.2 degrees C were obtained which are in agreement with the minimum required for these applications.

2015

Design for Dependability and Autonomy of a Wearable Cardiac and Coronary Monitor

Authors
da Silva, JM; Oliveira, C; Mendes, B; Dias, R; Marques, T;

Publication
2015 EUROMICRO CONFERENCE ON DIGITAL SYSTEM DESIGN (DSD)

Abstract
Wearable vital signals monitoring systems are promoting new assistance approaches in the healthcare system and are essential for the future connected health paradigm. The present work addresses the design of a cardiac and coronary monitoring system taking into consideration dependability and autonomy issues. A fuzzy logic approach is used to determine, in case deviations in the captured electrocardiogram are detected, whether these are occurring in the patient or in the system. As for autonomy, the use of data compression versus extra data processing balance is analysed to find operating conditions for which compression is worth to be used.

2015

Design of a High Efficiency GaN-HEMT RF Power Amplifier

Authors
Gaddam, NK; da Silva, JM;

Publication
2015 Conference on Design of Circuits and Integrated Systems (DCIS)

Abstract
This paper presents the design and implementation of a GaN-HEMT, class-J power amplifier suitable for cognitive radio transceivers, i.e., which presents high-efficiency and wideband characteristics, being these maintained for large load variations. Simulation results are presented which show large-signal measurement results of 30 dB gain with 60%-76% power-added efficiency (PAE) over a band of 1.3-2.3 GHz. Adaptivity to load changes is being developed to ensure PAE above 70% for large load variations.

2017

Correntropy applied to fault detection in analogue circuits

Authors
Da Silva, JM;

Publication
Proceedings of the 2017 IEEE 22nd International Mixed-Signals Test Workshop, IMSTW 2017

Abstract
Efficient test and diagnosis methods are required to ensure high levels of dependability of the electronic systems deployed to the market. These methods involve a trade-off in terms of accessibility to test nodes, test stimuli complexity, area overhead, and data processing that, altogether determine the impact that the involved operations have in the final cost, performance, and reliability presented by these systems. The work presented here describes preliminary results obtained with the application of correntropy as a means to efficiently analyse test responses in the fault detection decision process. © 2017 IEEE.

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