Percorrer por autor "Couto, Carlos"
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- A 2.4 GHz wireless electronic shirt for vital signals monitoringPublication . Carmo, João Paulo; Mendes, P.M.; Couto, Carlos; Correia, José H.The paper presents a wireless sensor network for wireless electronic shirts. This allows the monitoring of individual biomedical data, such as the cardio-respiratory function. The solution chosen to transmit the body’s measured signals for further processing was the use of a wireless link, working at the 2.4 GHz ISM band. A radio-frequency (RF) CMOS transceiver chip was designed in the UMC RF 0.18 μm CMOS process. The power supply of the RF CMOS transceiver is of only 1.5 V, thus it can be supplied by a single coin-sized battery. The receiver has a sensibility of -60 dBm and consumes 6.2 mW. The transmitter delivers an output power of 0 dBm with a power consumption of 15.6 mW. Innovative topics concerning efficient power management was taken into account during the design of the RF CMOS transceiver.
- 2.4 GHz wireless sensor network for smart electronic shirtsPublication . Carmo, João Paulo; Mendes, P.M.; Couto, Carlos; Correia, José H.This paper presents a wireless sensor network for smart electronic shirts. This allows the monitoring of individual biomedical data, such the cardio-respiratory function. The solution chosen to transmit the body’s measured signals for further processing was the use of a wireless link, working at the 2.4 GHz ISM band. A radio-frequency transceiver chip was designed in a UMC RF 0.18 μm CMOS process. The power supply of the transceiver is 1.8 V. Simulations show a power consumption of 12.9 mW. Innovative topics concerning efficient power management was taken into account during the design of the transceiver.
- A 2.4-GHz low-power/low-voltage wireless plug-and-play module for EEG applicationsPublication . Carmo, João Paulo; Dias, Nuno; Silva, Hélder; Mendes, P.M.; Couto, Carlos; Correia, José H.This paper presents a plug-and-play module for wireless electroencephalogram (EEG) applications. The wireless module is composed by an electrode, processing electronics, a radio-frequency (RF) transceiver, and an associated antenna. The RF transceiver was fabricated in the UMC RF 0.18 mum CMOS process, and operates in the 2.4-GHz ISM band. The receiver has a sensitivity of -60 dBm and a power consumption of 6.3 mW from a 1.8 V supply. The transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW, for a range of 10 m. It is also presented the electrical performance and comparison between different electrodes for EEG applications, namely sputtered titanium nitride (TiN) electrodes, standard sintered silver/silver chloride (Ag/AgCl) ring electrodes and sputtered iridium oxide (IrO2) electrodes. The experimental results show a better performance of the sputtered IrO2 electrodes compared with the standard sintered Ag/AgCl ring electrodes. These results promise a new opportunity for the application of a dry IrO2 electrodes in wireless modules for using in a wearable EEG braincap. These wireless EEG modules will allow patients to wear a brain cap and maintain their mobility, while simultaneously having their electrical brain activity monitored.
- A 2.4-GHz RF CMOS transceiver for wireless sensor applicationsPublication . Carmo, João Paulo; Mendes, P.M.; Couto, Carlos; Correia, José H.The paper describes a radio frequency transceiver designed in UMC RF 0.18 µm CMOS process. This process has a poly and six metal layers, allowing the use of integrated spiral inductors (with a reasonable quality factor), high resistor value (a special layer is available) and a low-power supply of 1.8 V. This RF CMOS transceiver will be applied to implemented a wireless sensors network in a wireless electronic shirt for helping health professionals with rapid, accurate and sophisticated diagnostic concerning cardiopulmonary disease in order to evaluate the presence of breathing disorders in free-living patients. Without proper design, communication will increase network power consumption significantly because listening and emitting are power-intensive activities. Thus, in order to optimise power consumption, it was included in the design of the RF transceiver, the use of control signals. With these control signals it is possible to enable and disable all the transceiver subsystems. These signals allows for example to switch off the receiver when a RF signal is being transmitted, to switch off the transmitter when a RF signal is being received, and to put the transceiver in sleeping mode when neither RF signals are being transmitted, nor being received.
- A 2.4-GHz wireless sensor network for smart electronic shirts integrationPublication . Carmo, João Paulo; Mendes, P.M.; Afonso, José A.; Couto, Carlos; Correia, José H.A typical sensing module is composed of sensors, interface electronics, a radio-frequency (RF) CMOS transceiver and an associated antenna. A 2.4-GHz RF transceiver chip was fabricated in a UMC 0.18 μm CMOS process. The receiver has a sensibility of -60 dBm and consumes 6.3 mW from a 1.8 V supply. The transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW. Innovative topics concerning efficient power management was taken into account during the design of the transceiver. A solution of individual sensing modules allows a plug-and-play solution. The target application is the integration of a wireless sensor network in smart electronic shirts, for monitoring the cardio-respiratory function and posture.
- 5.7 GHz on-chip antenna/RF CMOS transceiver for wireless sensor networkSPublication . Carmo, João Paulo; Mendes, P.M.; Couto, Carlos; Correia, José H.This paper describes a chip-size antenna for operation at 5.7 GHz, assembled with a low-power, low-voltage RF CMOS transceiver, fabricated in UMC RF CMOS 0.18 μm process. Measurements shown a patch antenna with the central frequency of 5.705 GHz, a bandwidth of 90 MHz at −10 dB of return loss, a directive gain of 0.3 dB, with an efficiency of 18%, and a transceiver with a measured total power consumption of 23 mW. This microsystem is intended for the use in each wireless node of a wireless sensor network mounted in a wireless electronic shirt, that monitors the cardio-respiratory function and posture.
- Accuracy of 2D numerical models towards the prediction of the fire resistance on LSF partition wallsPublication . Piloto, P.A.G.; Gomes, Stephan; Torres, Leonardo; Couto, Carlos; Real, Paulo VilaLightweight steel framing (LSF) walls are commonly used in modern buildings due to their high strength-to -weight ratio and readiness for installation. However, empty cavities within these walls can pose a fire risk if not properly addressed. In order to ensure the fire resistance and performance of LSF walls with empty cavities, various modelling techniques can be employed. Two-dimensional thermal models can also be used to simulate the behaviour of LSF walls with empty cavities in a fire scenario. These models can predict the spread of heat through the empty cavity, allowing designers to identify potential fire hazards and make adjustments to the design to mitigate those risks.Three different computational solution methods were used to compare the fire performance of LSF walls with void cavities. Solution method 1 considers the air-structure interaction in the cavity region. Solution method 2 considers the existence of interface elements for the radiation heat transfer in the cavity region allowing the cavity temperature prediction. Solution method 3 considers the convection and radiation in the cavity region with a prescribed cavity temperature from experiments (hybrid). Solution methods 1 and 3 give a small root mean square error (RMSE), when compared with solution method 2. Solution method 3 gives a better approx-imation because can capture the main fire events during the fire, such as the cracks and fall off. Based on the parametric study, a new proposal is presented to predict the fire resistance by insulation, depending on the gypsum type and thickness.
- Accurate 3D numerical models for the fire performance on lsf partition walls under different fire scenariosPublication . Piloto, Paulo A.G.; Silva, Renata; Frizzera, Giovanna; Torres, Leonardo; Couto, Carlos; Vila Real, Paulo; Mesquita, Luís M.R.; Lopes, NunoThis study presents the development and validation of advanced 3D numerical models to analyse the fire performance of non-load-bearing Light Steel Frame (LSF) partition walls under different fire scenarios, specifically the standard ISO 834 and HYDROCARBON fire. Medium-scale experimental fire resistance tests from prior research were used for validation, focusing on LSF walls with and without cavity insulation (external composite insulation). Three computational solution methods were compared and used to predict the fire behaviour of LSF walls with a void cavity. The finite element method was employed for transient thermal analysis with temperature-dependent material properties, including adaptations to simulate material degradation such as gypsum board cracking and rock wool melting under HYDROCARBON fire conditions. Hydrocarbon fires reduced fire resistance by an average of 57% compared to ISO 834 fires for cavity-insulated walls, whereas external insulation configurations showed less reduction.
- Avaliação do comportamento ao fogo de paredes exteriores em light steel framingPublication . Torres, Leonardo; Couto, Carlos; Vila Real, Paulo; Piloto, Paulo A.G.Este estudo avaliou o comportamento ao fogo de paredes em Light Steel Framing (LSF) através de quatro ensaios experimentais de pequena escala, sujeitos à curva de incêndio padrão ISO 834 pelo lado interior (revestido com gesso) e exterior (revestido com ISOLPRO). Como esperado, verificaram-se diferenças significativas no isolamento térmico (I) e no aquecimento dos perfis metálicos. As simulações numéricas por elementos finitos confirmaram a tendência observada experimentalmente, sobretudo no cenário de fogo pelo lado interior. Os ensaios demonstram-se essenciais para a calibração de modelos e para o desenvolvimento de soluções construtivas mais seguras.
- Comportamento ao fogo de vigas alveolares com aberturas circularesPublication . Silva, Luana Vidoti da; Mesquita, Luís M.R.; Piloto, Paulo A.G.; Ferreira, Débora; Barreira, Luísa; Lopes, Nuno; Couto, Carlos; Vila Real, PauloO comportamento de vigas alveolares de aço à flexão, especialmente em situação de incêndio, foi investigado através de uma campanha experimental e da validação de um modelo numérico. Os resultados demonstram que o modelo de elementos finitos prevê com boa precisão a capacidade de carga e os modos de falha observados nos ensaios. A análise evidencia que a geometria das aberturas condiciona o modo de colapso à temperatura ambiente, enquanto o aumento da temperatura pode alterar o mecanismo de falha para uma mesma geometria, promovendo o colapso por encurvadura do montante da alma ou pelo Mecanismo de Vierendeel. A investigação apresenta dados experimentais relevantes e um modelo numérico validado, essenciais para o desenvolvimento de futuras regras de dimensionamento.