2011
Authors
Almeida, VG; Pereira, T; Borges, E; Cardoso, JMR; Correia, C; Pereira, HC;
Publication
PECCS 2011: PROCEEDINGS OF THE 1ST INTERNATIONAL CONFERENCE ON PERVASIVE AND EMBEDDED COMPUTING AND COMMUNICATION SYSTEMS
Abstract
An arterial pressure waveform recorder and analyser based on a Microchip PIC microcontroller (mu C), dsPIC33FJ256GP710 is described in this article. Our purpose is to develop a dsPIC based signal monitoring and processing system for cardiovascular studies, specially dedicated to arterial pressure waveform (APW) capture. We developed a piezoelectric (PZ) probe designed to reproduce the APW from the pulsatile activity taken non-invasively at the vicinity of a superficial artery. The advantages in developing a microcontroller based system show up in decreasing the associate cost, as well as in increasing the functionality of the system. Based on a MathWorks Simulink platform, the system supports the development and transfer of program code from a personal computer to the microcontroller, and evaluation of its execution on rapid prototyping hardware. Results demonstrate that embedded system can be an alternative to be used in autonomous cardiovascular probes. Although additional studies are still required, this probe seems to be a valid, low cost and easy to use alternative to expensive and hard to manipulate devices in the market.
2011
Authors
Pereira, HC; Pereira, T; Almeida, V; Cardoso, J; Maldonado, J; Malaquias, JL; Simoes, JB; Correia, C;
Publication
1st Portuguese Meeting in Biomedical Engineering, ENBENG 2011
Abstract
Over the last years, great emphasis has been placed on the role of arterial stiffness in the development of cardiovascular diseases. This hemodynamic parameter, generally associated to age and blood pressure increase, can be assessed by the measurement of pulse wave velocity (PWV). Currently available devices that measure PWV are expensive and need to be operated by skilled medical staff, reducing the potential of ambulatory setting. This research project aims at developing and testing the sensoring and algorithmic basis of an alternative and non-invasive device for PWV assessment. The proposed device is based on a double-headed sensor probe and allows the assessment of PWV in one single location, providing important information on local arterial hemodynamics. Although studies to validate the clinical use of this system are still required, it has already demonstrated good performance on a dedicated test bench system, capable of reproducing a range of relevant cardiovascular system's properties. © 2011 IEEE.
2010
Authors
Luo, Q; Pereira, JR; Salgado, HM;
Publication
40TH EUROPEAN MICROWAVE CONFERENCE
Abstract
In this paper, a new multiband antenna consisting of a coplanar patch antenna over an active artificial magnetic conductor (AMC) ground plane is demonstrated. The AMC ground plane, which has been proven to be very effective in the design of low profile antennas, consists of 4x4 square shaped unit cells. By connecting RF switches between adjacent unit cells, a group of four unit cells can be aggregated to a larger size unit cell. In this proposed antenna, the coplanar patch is placed 2mm above the AMC ground plane. It is observed that it is possible to use the patch to excite the AMC ground plane to become another resonant element. Moreover, operation in two more resonant frequencies can be achieved by reconfiguring the unit size of the AMC ground plane. In this way, one coplanar antenna can operate at four different bands with a simple configuration while keeping a low profile. In this work, it is shown that using the actively tuned AMC ground plane, one coplanar patch antenna can operate at 5.8GHz, 5.2GHz, 4.5GHz and 2.4GHz with a good operation bandwidth (S11<-10dB), which includes the entire required bands for WLAN 802.11a/b/g applications. The experimental and simulated results for impedance and radiation performance characterization are presented. All of the design and optimization work have been conducted using the Ansoft HFSS, which is a 3D full-wave electromagnetic field simulation software.
2010
Authors
Rocco Giraldi, MTM; Rocha, AM; Neto, B; Correia, C; Segatto, MEV; Pontes, MJ; Barbero, APL; Costa, JCW; Martinez, MAG; Frazao, O; Baptista, JM; Salgado, HM; Marques, MB; Teixeira, ALJ; Andre, PS;
Publication
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS
Abstract
This article analyzes experimentally the limitations observed in lightwave systems using distributed Raman amplifiers operating under large pump power input conditions. The Brillouin effect is observed as the pump power reaches 1 W. The presence of Brillouin peaks degrades the performance of the system. The Raman amplification occurs in single mode and dispersion compensating fibers, being evaluated in a link at transmission rate of 40 Gb/s. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1331-1335, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25162
2010
Authors
Oliveira, JMB; Silva, S; Pessoa, LM; Coelho, D; Salgado, HM; Castro, JCS;
Publication
Proceedings - 2010 IEEE International Topical Meeting on Microwave Photonics, MWP 2010
Abstract
This paper presents a performance evaluation of a multiband-orthogonal frequency division multiplexing (MBOFDM) ultra-wideband (UWB) signal transmission over two types of perfluorinated graded-index polymer optical fibers (PFGI-POFs) with diameters of 62.5 µm and 120 µm, using a lowcost optical transceiver. Experimental measurements of packet error rate (PER) and minimum transmitted powers to achieve the maximum allowed PER show that it is possible to have a viable transmission at data rates of 480 Mbps, 200 Mbps and 53.3Mbps over 100, 150 and 200 meters of PF-GI-POF, respectively, preceded by a 1 meter wireless link. ©2010 IEEE.
2010
Authors
Luo, Q; Salgado, HM; R.Pereira, J;
Publication
Final Program and Book of Abstracts - iWAT 2010: 2010 International Workshop on Antenna Technology: Small Antennas, Innovative Structures and Materials
Abstract
This paper presents the design of a single feed multiband printed monopole antenna array using the 2nd generation of the Minkowski fractal geometry. The multiband operation is achieved by a suitable chosen of the size and iteration of the fractal geometry, which is optimized using the EM simulation tool Ansoft HFSS. During this work, it is found that adding a rectangular stub on the ground plane, the impedance match of the antenna can be improved with little influence on the original resonant frequencies. This finding has been confirmed by both simulation and measurement results. Meanwhile, the antenna array on a PDA size substrate was also designed and fabricated. The experimental results show that it can operate from 2.32 to 2.49 and from 5.1 to 5.88 GHz, which covers the required bands for IEEE 802.11a/b/g (2.41-2.48 GHz, 5.15-5.35 GHz and 5.725-5.875 GHz) applications. Measurements indicate that the maximum gain of this printed monopole array can reach 2.3 dBi at lower band and 5.6 dBi at upper band. The simulation results show that the radiation efficiency of this antenna array is 86% at 2.4 GHz, 82% at 5.2 GHz and 89% at 5.8 GHz. ©2010 IEEE.
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