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Publications

2012

Digital Control of a White Light Interrogation System for Optical Fiber Interferometers

Authors
Velosa, E; Gouveia, C; Frazao, O; Jorge, PAS; Baptista, JM;

Publication
IEEE SENSORS JOURNAL

Abstract
A system to interrogate optical fiber interferometric sensors with digital control is presented. The system is based on a receiving white light Mach-Zehnder interferometer and is capable of operating with four distinct synthetic and pseudo-heterodyne signal detection schemes. A differential phase detection scheme was implemented and system performance with the different processing schemes was compared using fiber Bragg grating based Fabry-Perot cavity strain sensors. With a lock-in time constant of 1 s, most digital techniques were able to nearly match the performance of a standard hardware system, demonstrating the feasibility of low-cost high-resolution interferometric systems operated with virtual instrumentation.

2012

Multimode Interference as a Tool for Fiber Sensing

Authors
Santos, JL; Silva, S; Ferreira, LA; Araujo, FM; Frazao, O;

Publication
FIBER OPTIC SENSORS AND APPLICATIONS IX

Abstract
Fiber optic modal interferometry has been around as a sensing concept since the outcome of fiber optic sensing. Initially supported by the utilization of standard Hi-Bi fibres associated to polarimetric modal interference, later this sensing approach evolved to modal interference based on spatial modes propagating in the core, on spatial modes propagating in the core and in the cladding with coupling performed by fibre devices such as long period gratings and tapers, and more recently on several types of modes propagating in photonic crystal fibers. This paper will address fiber optic sensing based on modal interferometry, and configurations of different type researched in last years will be presented and their performance compared.

2012

Automatic Localization of the Optic Disc in Retinal Images Based on the Entropy of Vascular Directions

Authors
Mendonca, AM; Cardoso, F; Sousa, AV; Campilho, A;

Publication
IMAGE ANALYSIS AND RECOGNITION, PT II

Abstract
This paper proposes an automatic method for estimating the location of the optic disc in color images of the retina. The proposed methodology is founded in a new concept, the entropy of vascular directions, which proved to be a reliable measure for assessing the convergence of vessels around an image point. To improve the robustness of the method, the search for the maximum value of entropy is restricted to image areas with high intensity. This new method was evaluated in two publicly available databases, containing both normal and pathological images, and was able to obtain a valid location for the optic disc in 115 out of the 121 images of the two datasets.

2012

Blind navigation support system based on Microsoft Kinect

Authors
Filipe, V; Fernandes, F; Fernandes, H; Sousa, A; Paredes, H; Barroso, J;

Publication
PROCEEDINGS OF THE 4TH INTERNATIONAL CONFERENCE ON SOFTWARE DEVELOPMENT FOR ENHANCING ACCESSIBILITY AND FIGHTING INFO-EXCLUSION (DSAI 2012)

Abstract
This paper presents a system which extends the use of the traditional white cane by the blind for navigation purposes in indoor environments. Depth data of the scene in front of the user is acquired using the Microsoft Kinect sensor which is then mapped into a pattern representation. Using neural networks, the proposed system uses this information to extract relevant features from the scene, enabling the detection of possible obstacles along the way. The results show that the neural network is able to correctly classify the type of pattern presented as input.

2012

Iberia 2.0 A Way To Leverage Web 2.0 In Organizations

Authors
Martins, J; Goncalves, R; Pereira, J; Cota, M;

Publication
INFORMATION SYSTEMS AND TECHNOLOGIES

Abstract
The Internet and specially the Web 2.0, when combined with the organizations business processes and used in their e-business initiatives, may bring an enormous set of competitive advantages. Despite the slow pass at which the organizations are incorporating Web 2.0 in their business initiatives, these actions are still being made without following any methodology or set of guidelines, thus resulting in inconstant return of investment. With this in mind, we present a project that, by analyzing and studying several case studies, aims on achieving a methodology or a set of guidelines that allow organizations to better plan and execute their Web 2.0 business initiatives.

2012

Extension and Implementation of ClassSheet Models

Authors
Cunha, J; Fernandes, JP; Mendes, J; Saraiva, J;

Publication
2012 IEEE SYMPOSIUM ON VISUAL LANGUAGES AND HUMAN-CENTRIC COMPUTING (VL/HCC)

Abstract
In this paper we explore the use of models in the context of spreadsheet engineering. We review a successful spreadsheet modeling language, whose semantics we further extend. With this extension we bring spreadsheet models closer to the business models of spreadsheets themselves. An addon for a widely used spreadsheet system, providing bidirectional model-driven spreadsheet development,

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