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Publicações

Publicações por Raul Morais

2008

A ZigBee multi-powered wireless acquisition device for remote sensing applications in precision viticulture

Autores
Morais, R; Fernandes, MA; Matos, SG; Serodio, C; Ferreira, PJSG; Reis, MJCS;

Publicação
COMPUTERS AND ELECTRONICS IN AGRICULTURE

Abstract
This paper is part of a long-term effort to introduce precision viticulture in the region of Demarcated Region of Douro. It presents the architecture, hardware and software of a platform designed for that purpose, called MPWiNodeZ. A major feature of this platform is its power-management subsystem, able to recharge batteries with energy harvested from the surrounding environment from up to three sources. It allows the system to sustain operation as a general-purpose wireless acquisition device for remote sensing in large coverage areas, where the power to run the devices is always a concern. The MPWiNodeZ, as a ZigBee (TM) network element, provides a mesh-type array of acquisition devices ready for deployment in vineyards. In addition to describing the overall architecture, hardware and software of the monitoring system, the paper also reports on the performance of the module in the field, emphasising the energy issues, crucial to obtain self-sustained operation. The testing was done in two stages: the first in the laboratory, to validate the power management and networking solutions under particularly severe conditions, the second stage in a vineyard. The measurements about the behaviour of the system confirm that the hardware and software solutions proposed do indeed lead to good performance. The platform is currently being used as a simple and compact yet powerful building block for generic remote sensing applications, with characteristics that are well suited to precision viticulture in the DRD region. It is planned to be used as a network of wireless sensors on the canopy of vines, to assist in the development of grapevine powdery mildew prediction models.

2009

An activation circuit for battery-powered biomedical implantable systems

Autores
Morais, R; Frias, CM; Silva, NM; Azevedo, JLF; Serodio, CA; Silva, PM; Ferreira, JAF; Simoes, JAO; Reis, MC;

Publicação
SENSORS AND ACTUATORS A-PHYSICAL

Abstract
Biomedical implantable devices in real-time telemetry applications offer many advantages to study and monitor physiologic parameters in human and animal bodies. As in power-constrained implantable devices, batteries and wires are two key issues that usually compromise their application. Inductive coupling is a well-established technology because it replaces simultaneously the wired connection and avoids the use of batteries. In stand-alone applications that requires total freedom of movements, this technology may present some constrains. On the other hand,very-low power electronics, advanced energy harvesting techniques and smaller implantable rechargeable batteries makes now possible the conception of fully autonomous implantable devices. This paper describes an activation circuit used to completely turn-off battery-powered implantable devices. In addition, it allows the reception of embedded commands, suitable for calibration and sensor selection purposes. Results from an experimental device to be used in a smart hip prosthesis telemetry system for loosening detection shows the usefulness of the proposed activation concept.

2009

A Windows-Based Software Package to Evaluate Residual Stresses by the Incremental Hole-Drilling Technique

Autores
Nobre, JP; Dias, AM; Domingos, AJ; Morais, R; Reis, MJCS;

Publicação
COMPUTER APPLICATIONS IN ENGINEERING EDUCATION

Abstract
A new software package for the incremental hole-drilling technique (IHD) is presented in connection with undergraduate mechanical engineering education. The main available technical residual stresses evaluation procedures for applying MID in isotropic materials are reviewed and have been included in the package, it has an easy-to-use, friendly interface, and can be used as a tool to teach the IHD technique or as a laboratory to study its applicability to real world problems. A set of exercises have been prepared, which are freely distributed to our students, in order to show the full potential of the package, but the students can also do simulations and experiments with their own data. (C) 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 351-362, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20225

2011

Double permanent magnet vibration power generator for smart hip prosthesis

Autores
Morais, R; Silva, NM; Santos, PM; Frias, CM; Ferreira, JAF; Ramos, AM; Simoes, JAO; Baptista, JMR; Reis, MC;

Publicação
SENSORS AND ACTUATORS A-PHYSICAL

Abstract
Ever since the first studies about biomedical implantable devices, the problem of how to energize them has stood out as both important and notoriously difficult to solve. In order to extend the lifetime of implants, it is imperative to develop power generators that are autonomous, safe and maintenance-free. Energy harvesting is a natural way of meeting these requirements. First, the energy source is theoretically everlasting, a fact that helps to guarantee the autonomy. Second, the energy is obtained from the environment of the application itself, contributing to its safety. Finally, a properly designed energy harvesting system is very unlikely to ever require maintenance. This paper follows this line and describes an electromagnetic power transducer that harvests electrical energy from the human gait and stores it. An efficient power management module uses the stored energy to energize the telemetric system of a smart hip prosthesis implant, enabling the early detection of loosening, the target application of this work. The system is able to extract a total 1912.5 mu J of usable energy under normal walking conditions.

2012

Nonlinear modeling of vibrational energy harvesters for smart prostheses

Autores
Morgado, ML; Morgado, LF; Henriques, E; Silva, N; Santos, P; Santos, M; Ferreira, J; Reis, M; Morais, R;

Publicação
26TH EUROPEAN CONFERENCE ON SOLID-STATE TRANSDUCERS, EUROSENSOR 2012

Abstract
We present a nonlinear mathematical model for a low-size and micro-power vibrational energy harvester targeted to power smart prostheses and in particular hip prostheses. Constraints such as available volume, allowable total weight and energy transducer mechanism difficult the development of an optimal generator system, especially considering the low frequencies involved in the human gait. Since non-linear behavior often conducts to better experimental results than those obtained using linear models, a nonlinear model is being pursued to reduce the volume of the generator and maximize performance. By including the non-linear effects of magnetic levitation used to suspend the inertial mass, influence of friction and effects of inductor non-idealities, preliminary results indicate better generator's performance prediction which allows a more effective customization of the energy harvester. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.

2012

Multi-purpose and multi-source energy management system for biomedical implants

Autores
Silva, N; Santos, P; Ferreira, J; Santos, M; Reis, M; Morais, R;

Publicação
26TH EUROPEAN CONFERENCE ON SOLID-STATE TRANSDUCERS, EUROSENSOR 2012

Abstract
This paper describes a multi-purpose energy management system that can harvest energy from a multitude of power sources. In order to suffice power needs of a smart hip prosthesis, a prototype was built considering the use of two types of power sources: energy harvesting micro-power generators for intermittent implant electronics powering; wireless energy, by means of an activation system, responsible for, when needed, continuously powering the implant electronics and also configuring its mode of operation. Intermittently or continuously, it is now possible to energize more power demanding systems as the ones that uses a RF transceiver. The smart hip prosthesis can now become a wireless body sensor network node using LR-WPAN protocols such as Bluetooth low energy as is intended in this work. Preliminary results proved that is possible to energize a Bluetooth low energy module, for over 100 s, solely using the stored energy produced by one of the micro-power generators. (C) 2012 Elsevier Ltd....Selection and/or peer-review under responsibility of the Symposium Cracoviense Sp. z.o.o.

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