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Publications

2007

Cutting and packing

Authors
Oliveira, JF; Roberto Frias, R; Wascher, G;

Publication
EUROPEAN JOURNAL OF OPERATIONAL RESEARCH

Abstract

2007

Breast contour detection for the aesthetic evaluation of breast cancer conservative treatment

Authors
Cardoso, JS; Cardoso, MJ;

Publication
Advances in Soft Computing

Abstract
Cosmetic assessment of breast cancer conservative treatment (BCCT) plays a major role in the evaluation of this form of treatment. Objective assessment methods are being preferred to overcome the drawbacks of subjective evaluation. A recent computer-aided medical system was developed to objectively and automatically perform the aesthetic evaluation of the result of BCCT. In order to extract relevant features from the image, the detection of the breast contour is necessary. In this paper an algorithm based on the shortest path on a graph is proposed to detect the breast contour. The proposed method was applied to 300 breast images with an accuracy of 98%. © 2007 Springer-Verlag Berlin Heidelberg.

2007

Synthesis of Logic Circuits Using Fractional-Order Dynamic Fitness Functions

Authors
Reis, C; Machado, JAT; Cunha, JB;

Publication
PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, VOL 1

Abstract
This paper analyses the performance of a genetic algorithm using a new concept, namely a fractional-order dynamic fitness function, for the synthesis of combinational logic circuits. The experiments reveal superior results in terms of speed and convergence to achieve a solution.

2007

Improving early-season estimates of olive production using airborne pollen multi-sampling sites

Authors
Ribeiro, H; Cunha, M; Abreu, I;

Publication
AEROBIOLOGIA

Abstract
The aim of this study was to improve the accuracy of aeropalynological models to forecast yields in areas with heterogeneous characteristics by applying principal component analysis to integrate the airborne pollen sampled from more than one trap. The sampling was performed during the past seven years (1998-2004) in the main northeast olive regions of Portugal. Annual crop production was forecasted on the basis of airborne pollen concentration measured at flowering, comparing the performance of three different independent variables: total airborne pollen concentration sampled in each trap and a derived variable that was determined by principal component analysis of the total airborne pollen concentration sampled. The best predictive results were obtained using a logarithmic relationship with airborne pollen concentration principal component scores describing about 97% of olive fruit production variability over the last seven years. The use of this technique improved the ability of pollen to explain the production interannual variations by about 13%. The comparison between actual reported and the adjusted production showed an average spread deviation of 5%.

2007

Multimedia interface with an intelligent wheelchair

Authors
Martins, B; Valgode, E; Faria, P; Reis, LP;

Publication
COMPUTATIONAL MODELLING OF OBJECTS REPRESENTED IN IMAGES: FUNDAMENTALS, METHODS AND APPLICATIONS

Abstract
Many of the physically injured use electric wheelchairs as an aid to locomotion. Usually, for commanding this type of wheelchair, it is required the use of one's hands and this poses a problem to those who, besides being unable to use their legs, are also unable to properly use their hands. The aim of the work described here, is to create a prototype of a wheelchair command interface that do not require hand usage. Facial expressions were chosen instead, to provide the necessary visual information for the interface to recognize user commands. The facial expressions are captured by means of a digital camera and interpreted by an application running on a laptop computer on the wheelchair. The software includes digital image processing algorithms for feature detection, such as colour segmentation and edge detection, followed by the application of a neural network that uses these features to detect the desired facial expressions. A specific command language for controlling the intelligent wheelchair was also developed in the scope of this work, as well as a simple wheelchair simulator for validating the final results.

2007

A Simulation Study of XCP-b Performance in Wireless Multi-hop Networks

Authors
Abrantes, F; Ricardo, M;

Publication
Q2SWINET'07: PROCEEDINGS OF THE THIRD ACM WORKSHOP ON Q2S AND SECURITY FOR WIRELESS AND MOBILE NETWORKS

Abstract
XCP-b proposes a modification to the XCP router algorithm that computes the spare bandwidth. The modification removes the need for an XCP router to know the exact capacity of the channel, making it possible to use the XCP-b variant in transmission media where the capacity is hard to measure. An example of this kind of medium is the IEEE 802.11. Previous work shows that XCP-b behaves well in single-hop wireless networks and that it Outperforms TCP in terms of fairness, queuing delay, stability and efficiency when the bandwidth delay product of the network grows. In this paper we extend the validation and evaluation of XCP-b to the case of multi-hop wireless networks, both stand-alone and as access networks to other wired networks. The results show that XCP-b maintains its fundamental characteristics in wireless multi-hop scenarios, such as stable throughput and low standing queues, while distributing the bandwidth fairly and using the available capacity efficiently. The simulations also show that XCP-b produces congestion window values that are closer than TCP to the theoretical upper-bound which maximizes spatial reuse.

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