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Publications

2013

New optical probe approach using mixing effect in planar photodiode for biomedical applications

Authors
Pereira, T; Vaz, P; Oliveira, T; Santos, I; Leal, A; Almeida, V; Pereira, H; Correia, C; Cardoso, J;

Publication
OPTICAL SENSORS 2013

Abstract
The laser diode self-mixing technique is a well-known and powerful interferometric technique that has been used in biomedical applications, namely for the extraction of cardiovascular parameters. However, to construct an optical probe using the self-mixing principle which is able to acquire signals in the human carotid artery, some problems are expected. The laser diode has a small aperture area, which means that, for physiological sensing purposes, it can be considered as a point-like detector. This feature imparts difficulties to quality recording of physiological signals since the number of photons collected and mixed in the cavity of the photodiode is very small. In order to overcome this problem, a new mixing geometry based on an external large area planar photodiode (PD) is used in the probe, enabling a much larger number of photons to be collected, hence improving the quality of the signal. In this work, the possibility to obtain the mixing effect outside the laser cavity using an external photodetector, such as a planar photodiode, is demonstrated. Two test benches were designed, both with of two reflectors. The first one, which reflects the light beam with the same frequency of the original one is fixed, and the second one, is movable, reflecting the Doppler shifted light to the photodetector. The first test bench has a fixed mirror in front of the movable mirror, creating an umbra and penumbra shadow above the movable mirror. To avoid this problem, another test bench was constructed using a wedged beam splitter (WSB) instead of a fixed mirror. This new assembly ensures the separation of a single input beam into multiple copies that undergo successive reflections and refractions. Some light waves are reflected by the planar surface of WSB, while other light beams are transmitted through the WSB, reaching the movable mirror. Also in this case, the movable mirror reflects the light with a Doppler frequency shift, and the PD receives both beams. The two test benches were designed to demonstrate that it is possible to obtain mixing effect outside the laser cavity, using a planar photodiode. The Doppler spectrograms from the signals acquired in the test benches show that the signal frequency changes along time which correspond to the modulus of the derivative of the mirror movement, as expected in the self-mixing signals. Nevertheless, the test bench A showed better results than the test bench B. This fact probably results from the attenuation that the original beam suffers in each reflection and refraction in the WBS. Tests developed in the test benches opened the possibility to construct a probe that uses a planar photodiode with a large area to collect medical signals, and improve the quality of the acquisition with a better SNR.

2013

Conclusions

Authors
Diniz, PC; Cardoso, JMP; De F. Coutinho, JG; Petrov, Z;

Publication
Compilation and Synthesis for Embedded Reconfigurable Systems: An Aspect-Oriented Approach

Abstract
The REFLECT project aimed at developing, validating, and evaluating a novel compilation and synthesis approach for heterogeneous multi-core computing systems that relies on aspect-oriented specifications to convey critical domain knowledge to all design/development stages of an integrated toolchain. To reach these goals, we have devised a new compilation and synthesis foundation combining distinct but synergistic areas of research, namely, aspect-oriented programming, hardware compilation, design patterns, and hardware templates. © Springer Science+Business Media New York 2013. All rights are reserved.

2013

DEVELOPMENT OF A QUADRUPED ROBOT MODEL IN SIMMECHANICS (TM)

Authors
Silva, MF; Barbosa, RS; Castro, TS;

Publication
NATURE INSPIRED MOBILE ROBOTICS

Abstract
The presented work allowed the creation of a quadruped robot model (with flexible body, its legs and its hip and knee joints) in the virtual simulation program Simmechanics (TM). The final objective is to use this simulation model to optimize quadruped robot locomotion. The model developed accepts different gaits by direct introduction of the angular positions of the knee and hip joints. Feet-ground interaction was also modelled using a theoretic model described in the literature.

2013

CodeSkelGen - A program skeleton generator

Authors
Queiros, R;

Publication
OpenAccess Series in Informatics

Abstract
Existent computer programming training environments help users to learn programming by solving problems from scratch. Nevertheless, initiating the resolution of a program can be frustrating and demotivating if the student does not know where and how to start. Skeleton programming facilitates a top-down design approach, where a partially functional system with complete highlevel structures is available, so the student needs only to progressively complete or update the code to meet the requirements of the problem. This paper presents CodeSkelGen - a program skeleton generator. CodeSkelGen generates skeleton or buggy Java programs from a complete annotated program solution provided by the teacher. The annotations are formally described within an annotation type and processed by an annotation processor. This processor is responsible for a set of actions ranging from the creation of dummy methods to the exchange of operator types included in the source code. The generator tool will be included in a learning environment that aims to assist teachers in the creation of programming exercises and to help students in their resolution. © Ricardo Queirós.

2013

EVALUATING HOW WELL FILTERED WHITE NOISE MODELS THE RESIDUAL FROM SINUSOIDAL MODELING OF MUSICAL INSTRUMENT SOUNDS

Authors
Caetano, M; Kafentzis, G; Degottex, G; Mouchtaris, A; Stylianou, Y;

Publication
2013 IEEE WORKSHOP ON APPLICATIONS OF SIGNAL PROCESSING TO AUDIO AND ACOUSTICS (WASPAA)

Abstract
Nowadays, sinusoidal modeling commonly includes a residual obtained by the subtraction of the sinusoidal model from the original sound. This residual signal is often further modeled as filtered white noise. In this work, we evaluate how well filtered white noise models the residual from sinusoidal modeling of musical instrument sounds for several sinusoidal algorithms. We compare how well each sinusoidal model captures the oscillatory behavior of the partials by looking into how "noisy" their residuals are. We performed a listening test to evaluate the perceptual similarity between the original residual and the modeled counterpart. Then we further investigate whether the result of the listening test can be explained by the fine structure of the residual magnitude spectrum. The results presented here have the potential to subsidize improvements on residual modeling.

2013

Sensing Cloud Optimization to Solve ED of Units with Valve-Point Effects and Multi-fuels

Authors
Fonte, P; Monteiro, C; Barbosa, FM;

Publication
TECHNOLOGICAL INNOVATION FOR THE INTERNET OF THINGS

Abstract
In this paper a solution to an highly constrained and non-convex economical dispatch (ED) problem with a meta-heuristic technique named Sensing Cloud Optimization (SCO) is presented. The proposed meta-heuristic is based on a cloud of particles whose central point represents the objective function value and the remaining particles act as sensors "to fill" the search space and "guide" the central particle so it moves into the best direction. To demonstrate its performance, a case study with multi-fuel units and valve- point effects is presented.

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