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Publicações

Publicações por CTM

2011

Using a Prioritized Medium Access Control Protocol for Incrementally Obtaining an Interpolation of Sensor Readings

Autores
Andersson, B; Pereira, N; Tovar, E; Gomes, R;

Publicação
Solutions on Embedded Systems

Abstract

2011

Scalable Data Acquisition for Densely Instrumented Cyber-Physical Systems

Autores
Ehyaei, A; Tovar, E; Pereira, N; Andersson, B;

Publicação
2011 ACM/IEEE Second International Conference on Cyber-Physical Systems (ICCPS 2011)

Abstract
Consider the problem of designing an algorithm for acquiring sensor readings. Consider specifically the problem of obtaining an approximate representation of sensor readings where (i) sensor readings originate from different sensor nodes, (ii) the number of sensor nodes is very large, (iii) all sensor nodes are deployed in a small area (dense network) and (iv) all sensor nodes communicate over a communication medium where at most one node can transmit at a time (a single broadcast domain). We present an efficient algorithm for this problem, and our novel algorithm has two desired properties: (i) it obtains an interpolation based on all sensor readings and (ii) it is scalable, that is, its time-complexity is independent of the number of sensor nodes. Achieving these two properties is possible thanks to the close interlinking of the information processing algorithm, the communication system and a model of the physical world.

2010

Hybrid framework for evaluating video object tracking algorithms

Autores
Carvalho, P; Cardoso, JS; Corte Real, L;

Publicação
ELECTRONICS LETTERS

Abstract
A simple and efficient hybrid framework for evaluating algorithms for tracking objects in video sequences is presented. The framework unifies state-of-the-art evaluation metrics with diverse requirements in terms of reference information, thus overcoming weaknesses of individual approaches. With foundations on already demonstrated and well known metrics, this framework assumes the role of a flexible and powerful tool for the research community to assess and compare algorithms.

2010

Successive refinement of side information for multi-view distributed video coding

Autores
Ciobanu, L; Corte Real, L;

Publicação
MULTIMEDIA TOOLS AND APPLICATIONS

Abstract
Inter-camera registration in multi-view systems with overlapped views has a particularly long and sophisticated research history within the computer vision community. Moreover, when applied to Distributed Video Coding, in systems with at least one moving camera it represents a real challenge due to the necessary data at decoder for generating the side information without any a priori knowledge of each instant camera position. This paper proposes a solution to this problem based on successive multi-view registration and motion compensated extrapolation for on-the-fly re-correlation of two views at decoder. This novel technique for side information generation is codec-independent, robust and flexible with regard to any free motion of the cameras. Furthermore, it doesn't require any additional information from encoders nor communication between cameras or offline training stage. We also propose a metric for an objective assessment of the multi-view correlation performance.

2010

Tunable Multiband Antenna with an Active Artificial Magnetic Conductor Ground Plane

Autores
Luo, Q; Pereira, JR; Salgado, HM;

Publicação
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

RAYLEIGH ASSISTED BRILLOUIN EFFECTS IN DISTRIBUTED RAMAN AMPLIFIERS UNDER SATURATED CONDITIONS AT 40 Gb/s

Autores
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;

Publicação
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

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