Loading...
9 results
Search Results
Now showing 1 - 9 of 9
- Application of Wireless Sensor Networks to the AutomobilePublication . Tavares, Jorge; Velez, Fernando José; Ferro, João MiguelSome applications of Wireless sensor networks (WSNs) to the automobile are identified, and the use of MICAz motes operating at 2.4GHz is considered together with TinyOS support. These WSNs are being conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A survey on WSNs concepts is presented, and the wireless sensor network itself (transmitter/receiver/control board) is developed. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed, and solutions are proposed.
- Application of Wireless Sensor Networks to the AutomobilePublication . Tavares, Jorge; Velez, Fernando José; Ferro, João MiguelSome applications of Wireless sensor networks (WSNs) to the automobile are identified, and the use of MICAz motes operating at 2.4GHz is considered together with TinyOS support. These WSNs are being conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A survey on WSNs concepts is presented, and the wireless sensor network itself (transmitter/receiver/control board) is developed. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed.
- Identification of the Opportunistic Radio Frequency Bands for Energy Harvesting in Wireless Body Area NetworksPublication . Barroca, Norberto; Borges, Luís M.; Tavares, Jorge; Velez, Fernando J.; Chávez-Santiago, Raul; Balasingham, I.This paper presents the spectrum opportunities for radio frequency (RF) energy harvesting enabling to power supply future wireless body area networks (WBANs). The field trials have been performed in Covilhã by using the NARDA-SMR spectrum analyser with measuring antenna. Besides, this work addresses physical (PHY), medium access control (MAC) and network layer design aspects, by considering cognitive radio (CR) opportunities by means of the identification of the most promising bands.
- Desenvolvimento, simulação e validação de protocolos MAC e de encaminhamento para redes de sensores sem fiosPublication . Tavares, Jorge Miguel da Silva; Velez, Fernando José da SilvaA optimização de protocolos com elevada eficiência energética em redes de sensores sem fios constitui um desafio e a sua aplicação em contextos de automação de processos e recolha de dados apresentou-se como uma grande motivação. Simularam-se aplicações capazes de encaminhar os dados pela rede até ao nó Sink para vários protocolos com diferentes parâmetros ajustáveis, tais como o tempo de escuta; dutycycle e o período de contenção. Consideraram-se sensores MICAz da Crossbow, a funcionar a 2,4GHz (IEEE 802.15.4) e suportados pelo sistema operativo TinyOS para instalação prática da aplicação nos nós sensores, ou suportada pelo simulador Castalia/OMNet++. Como cenário para as aplicações sem mobilidade, considera-se uma área para plantação onde os nós sensores a controlar a humidade do solo. Para as aplicações com mobilidade, considera-se que os nós sensores estão a monitorizar a localização de cada animal duma manada. Verificou-se, através de simulação em Castalia, que quanto maior for o período de escuta maior será o consumo de energia. Nas aplicações com mobilidade, o protocolo S-MAC é o que apresenta uma eficiência energética superior. Nas aplicações sem mobilidade, num cenário com 36 nós dispostos numa grelha rectangular, conclui-se que o protocolo T-MAC tem um desempenho energético ligeiramente superior. Caso se esteja a utilizar uma RSSF, numa aplicação prática em que todos os nós têm uma função crítica, deve-se escolher um valor para o período de contenção correspondente ao valor mais reduzido do desvio padrão da energia consumida. Caso a função de um nó sensor não seja crítica para o sistema, o valor óptimo para o período de contenção é dado pelo valor mínimo da média de consumo de energia da rede. No cenário considerado, os valores óptimos para o período de contenção são 40 e 50 ms, para os casos onde missão individual de cada nó é ―crítica‖ ou ―não crítica‖, respectivamente.
- Spectrum opportunities for electromagnetic energy harvesting from 350 MHz to 3 GHzPublication . Tavares, Jorge Miguel da Silva; Barroca, Norberto; Saraiva, Henrique M.; Borges, Luís M.; Velez, Fernando J.; Loss, Caroline; Salvado, Rita; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno BorgesThis paper presents spectrum opportunities for radio frequency (RF) energy harvesting identified through power density measurements from 350 MHz to 3 GHz. The field trials have been performed in two different cities (Covilha and Lisbon), by using the NARDA-SMR spectrum analyser with measuring antenna, and the Signal Hound spectrum analysers, respectively. The scope of our research considers RF energy harvesting devices, enabling to convert RF energy to direct current (DC), providing an alternative source to power supply wireless sensor network (WSN) devices. Printed antennas, able to operate at GSM (900/1800) bands, are proposed with gains of the order of 1.8-2.06 dBi and efficiency 77.6-84%. Guidelines for the choice of textile materials for a wearable antenna are also provided.
- Experimental Characterization of Wearable Antennas and Circuits for RF Energy Harvesting in WBANsPublication . Saraiva, Henrique Morais; Borges, Luís M.; Pinho, Pedro; Gonçalves, Ricardo; Chavez-Santiago, Raul; Barroca, Norberto; Tavares, Jorge; Gouveia, Paulo T.; Carvalho, Nuno Borges; Balasingham, Ilangko; Velez, Fernando J.; Loss, Caroline; Salvado, RitaField trials have been performed in Covilhã to identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. Based on the identification of the most promising opportunities, a dual-band printed antenna was conceived, operating at GSM bands (900/1800), with gains of 1.8 and 2.06 dBi, and efficiency varying from 77.6 to 82%, for the highest and lowest operating frequency bands, respectively. In this paper, guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are briefly discussed. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with and without impedance matching circuit) responsible for RF energy harvesting. All the three prototypes (1, 2 and 3) can power supply the sensor node for RF received powers of 2 dBm, -3 dBm and -4 dBm, and conversion efficiencies of 6, 18 and 20%, respectively.
- Application of Wireless Sensor Networks to AutomobilesPublication . Tavares, Jorge; Velez, Fernando J.; Ferro, João MiguelSome applications of Wireless Sensor Networks (WSNs) to the automobile are identified, and the use of Crossbow MICAz motes operating at 2.4 GHz is considered together with TinyOS support. These WSNs are conceived in order to measure, process and supply to the user diverse types of information during an automobile journey. Examples are acceleration and fuel consumption, identification of incorrect tire pressure, verification of illumination, and evaluation of the vital signals of the driver. A brief survey on WSNs concepts is presented, as well as the way the wireless sensor network itself was developed. Calibration curves were produced which allowed for obtaining luminous intensity and temperature values in the appropriate units. Aspects of the definition of the architecture and the choice/implementation of the protocols are identified. Security aspects are also addressed.
- Developing Sustainable Communication Interfaces Through Fashion DesignPublication . Loss, Caroline; Salvado, Rita; Lopes, Catarina; Pinho, Pedro; Gonçalves, Ricardo; Velez, Fernando J.; Saraiva, Henrique Morais; Tavares, Jorge; Barroca, Norberto; Borges, Luís M.The recent technological developments made electronic devices become imperative and indispensable, being present in our daily routines, all over the world. But, the continuous exposition of people to the electromagnetic radiation might cause illness. Electrosmog is the invisible electromagnetic radiation that results from the usage of electric equipment and wireless technologies. Some studies present electro sensibility as a contemporary illness affecting more and more people. This paper analyses some of the challenges this reality puts to the fashion design and how textile materials may be used to protect the human body against the harmful radiation and to develop smart cloths incorporating textile antennas able to capture these radiations and feed low-frequency devices. Thus, one considers the notion of “Transparent Sustainability” and the search for the smart energy explorations of/or in the human body. This way, the association of fashion design and technology can transform the garment in a sustainable communication interface.
- Antennas and circuits for ambient RF energy harvesting in wireless body area networksPublication . Barroca, Norberto; Saraiva, Henrique M.; Gouveia, Paulo T.; Tavares, Jorge; Borges, Luís M.; Velez, Fernando J.; Loss, Caroline; Salvado, Rita; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno Borges; Chavez-Santiago, Raul; Balasingham, IlangkoIn this paper, we identify the spectrum opportunities for radio frequency (RF) energy harvesting through power density measurements from 350 MHz to 3 GHz. The field trials have been performed in Covilhâ by using the NAKDA-SMR spectrum analyser with a measuring antenna. Based on the identification of the most promising opportunities, a dual-band band printed antenna operating at GSM bands (900/1800) is proposed, with gains of the order 1.8-2.06 dBi and efficiency 77.6-84%. Guidelines for the design of RF energy harvesting circuits and choice of textile materials for a wearable antenna are also discussed. Besides, we address the guidelines for designing circuits to harvest energy in a scenario where a wireless body area network (WBAN) is being sustained by a TX91501 Powercasf® RF dedicated transmitter and a five-stage Dickson voltage multiplier responsible for harvesting the RF energy. The IRIS motes, considered for our WBAN scenario, can perpetually operate if the RF received power attains at least -10 dBm.