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Publications

Publications by CTM

2011

Evaluation of elementary functions without range reduction

Authors
Meireles, FA; Araujo, AJ;

Publication
VLSI CIRCUITS AND SYSTEMS V

Abstract
The evaluation of elementary functions can be performed by approximations using minimax polynomials requiring simple hardware resources. The general method to calculate an elementary function is composed by three steps: range reduction, computation of the polynomial in the reduced argument and range reconstruction. This approach allows a low-degree polynomial approximation but range reduction and reconstruction introduce a computation overhead. This work proposes an evaluation methodology without range reduction and range reconstruction steps. Applications that need to compute elementary functions may benefit from avoiding these steps if the argument belongs to a sub-domain of the function. Particularly in the context of embedded systems, applications related to digital signal processing most of the times require function evaluation within a specific interval. As a consequence of not doing range reduction, the degree of the approximant polynomials increases to maintain the required precision. Interval segmentation is an effective way to overcome this issue because the approximations are computed in smaller intervals. The proposed methodology uses non-uniform segmentation as a way to mitigate the problem arising from not carrying out range reduction. The benefits that come from applying interval segmentation to the general evaluation technique are limited by the range reduction and reconstruction steps because the segmentation only applies to the approximation step. However, when used in the proposed methodology it reveals more effective. Some elementary functions were implemented using the proposed methodology in a FPGA device. The metric used to characterize the proposed technique are the area occupation and the corresponding latency. The results of each implementation without range reduction were compared with the corresponding ones of the general method using range reduction. The results show that latency can be significantly reduced while the area is approximately the same.

2011

A True Power Detector for RF PA Built-In Calibration and Testing

Authors
da Mota, PF; da Silva, JM;

Publication
2011 DESIGN, AUTOMATION & TEST IN EUROPE (DATE)

Abstract
Different built-in self testing schemes for RF circuits have been developed resorting to peak voltage detectors. These are simple to implement but provide a conditional RF power measurement accuracy as impedance is assumed to be known. A true power detector is presented which allows obtaining more accurate measurements, namely as far as output load variations are concerned. The theoretical fundaments underlining the power detector operating principle are presented and simulation and experimental results obtained with a prototype chip are described which confirm the benefits of measuring true power, comparing to output peak voltage, when observing output load matching deviations and complex waveforms.

2011

A 3D simulation framework for safe ambient-assisted home care

Authors
Velasquez, C; Soares, C; Morla, R; Moreira, RS; Torres, JM; Sobral, P;

Publication
UBICOMM 2011 - 5th International Conference on Mobile Ubiquitous Computing, Systems, Services and Technologies; PECES 2011 - 3rd International Workshop on Pervasive Computing in Embedded Systems

Abstract
The Safe Home Care project focuses on assembling safe home assisted-living environments built on autonomous Off-The-Shelf systems. We argue that these smart spaces will contribute to relieve the pressure on health systems by providing the means for ambulatory and daily life assistance. However, the integration of disparate sovereign systems will not be easy to accomplish since the number of interaction scenarios will be impossible to predict and evaluate a priori. Therefore, we propose the SHC reflective middleware framework, conceived with two goals in mind: i) manage the safe integration of off-the-shelf systems (cf. interference-free) by exploiting reflection and 3D virtual world simulation; ii) provide non-intrusive pervasive interface mechanisms for home assisted-living actors. In this paper, we focus specifically on the first goal by providing the means for generating 3D simulations; the states generated during simulation are then analyzed by a graph-pruning algorithm to perceive feature interactions in pre-deployment phases. We evaluate our approach on specific home care use cases.

2011

Geographic Information Web Platform for Tourism

Authors
Oliveira, L; Rodrigues, A; Nunes, H; Dias, L; Coelho, A; Oliveira, JM; Carrapatoso, E; Leitao, MJ;

Publication
SISTEMAS E TECNOLOGIAS DE INFORMACAO, VOL I

Abstract
Several developments have been observed recently in areas such as Web development, social networks, interface design, recommendation systems and Geographic Information Systems (GIS). The integration of these developments can provide a superior experience, greater than the sum of their individual contributions, regarding user satisfaction. This paper proposes an integration of all these innovations in e-tourism, more specifically by the development of a Web based geographic information platform adaptable to any tourist region. As a case study, we also show how this platform was adapted to the Douro region, in Portugal. The Web platform developed as a proof of concept combines geospatial information from diverse and heterogeneous data sources, encompassing events, news, routes and points of interest (POI). This platform provides also a recommendation engine and features the possibility that users can contribute with content as part of the community, thus emerging a mini social network. © 2011 AISTI.

2011

Network infrastructure for academic IC CAD environments

Authors
Coke, P; Duarte, C; Cardoso, A; Tavares, VG; De Oliveira, PG;

Publication
EUROCON 2011 - International Conference on Computer as a Tool - Joint with Conftele 2011

Abstract
This paper presents an initiative to involve ECE undergraduate students in the design and deployment of a network infrastructure for an academic laboratory. The project aims at attaining a reliable and secure network for an IC CAD environment. The students focused on employing secure authentication, accounting and storage with single sign-on, based on enterprise-grade, open-source protocols. This initiative proved to be highly motivating and allowed the students to develop knowledge and hands-on experience on the area of network security. The resulting network design and core infrastructure is herein described as well as its deployment in a real microelectronics design environment. © 2011 IEEE.

2011

SURFACE RECONSTRUCTION FOR GENERATING DIGITAL MODELS OF PROSTHESIS

Authors
de Aquino, LCM; Leite, DATQ; Giraldi, GA; Cardoso, JS; Rodrigues, PSS; Neves, LAP;

Publication
VISAPP 2011: PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON COMPUTER VISION THEORY AND APPLICATIONS

Abstract
The restoration and recovery of a defective skull can be performed through operative techniques to implant a customized prosthesis. Recently, image processing and surface reconstruction methods have been used for digital prosthesis design. In this paper we present a framework for prosthesis modeling. Firstly, we take the computed tomography (CT) of the skull and perform bone segmentation by thresholding. The obtained binary volume is processed by morphological operators, frame-by-frame, to get the inner and outer boundaries of the bone. These curves are used to initialize a 2D deformable model that generates the prosthesis boundary in each CT frame. In this way, we can fill the prosthesis volume which is the input for a marching cubes technique that computes the digital model of the target geometry. In the experimental results we demonstrate the potential of our technique and compare it with a related one.

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