Browsing by Issue Date, starting with "2009-09"
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- Fuzzy Dynamic Matching Approach for Multi-Feature TrackingPublication . Lopes, Nuno Vieira; Couto, Pedro A.; Bustince, Humberto; Melo-Pinto, PedroFeature tracking is one of the most challenging and important tasks in computer vision playing an important role in several areas. In this paper, a new approach for multi feature tracking is presented. Information from the image gray levels and the features movement model is aggregated through the use of fuzzy sets with a fuzzy inference engine to give the final output. Experimental results are presented showing that the approach successfully copes with usual difficulties within this problem.
- A scaling analysis in the SIRI epidemiological modelPublication . Pinto, Alberto; Stollenwerk, Nico; Gouveia Martins, José Maria; Martins, JoséFor the spatial stochastic epidemic reinfection model SIRI, where susceptibles S can become infected I , then recover and remain only partial immune against reinfection R, we determine the phase transition lines using pair approximation for the moments derived from the master equation. We introduce a scaling argument that allows us to determine analytically an explicit formula for these phase transition lines and prove rigorously the heuristic results obtained previously.
- Comparing different electrode configurations using the 10-10 international system in tDCS: A finite element model analysisPublication . Faria, Paula; Leal, A.; Miranda, P.C.; Pascoal-Faria, Paula;For the past few years, the potential of transcranial direct current stimulation (tDCS) for the treatment of several pathologies has been investigated. Knowledge of the current density distribution is an important factor in optimizing such applications of tDCS. We use the finite element method to compare three different models in tDCS, where the stimulation electrodes (EEG electrodes) are placed in the 10-10 international system coordinates. We studied the focality and the distribution of the current density in depth and at the surface of the brain for three different electrode configurations. We show that the use of EEG electrodes increases the focality of tDCS, especially when one cathode and several anodes are used. Additionally, these electrodes need less injected current, can be placed at scalp positions whose relationship with the underlying cerebral cortex are known and allow the use of tDCS and EEG recording concomitantly.
- A novel monolithic silicon sensor for measuring acceleration, pressure and temperature on a shock absorberPublication . Ferreira, C.; Ventura, P.; Grinde, C.; Morais, R.; Valente, A.; Neves, C.; Reis, M.J.C.S.; Henriques Ferreira, Carlos Daniel; Neves, CarlosA fabricated micro-mechanical sensor to assess the condition of automotive shock absorbers is presented. The monolithic sensor, measures the oil temperature, acceleration and internal pressure of the shock absorber. A dual mass accelerometer with optimized beam geometry is used for acceleration readout. In addition, a 23.1 μm thickness square membrane and two buried resistors are used for pressure and temperature sensing respectively. The proposed miniaturized sensor can be effectively integrated with standard single- and dual-tube shock absorbers. The data acquired during normal vehicle operation can be continuously used to monitor the condition of the shock absorbers, allowing shock absorbers to be replaced before their degradation significantly reduce the comfort, performance and safety of the vehicle.
- Bioimplantable impedance and temperature monitor low power micro-system suitable for estrus detectionPublication . Miranda, N.; Morais, R.; Dias, M.; Viegas, C.; Silva, F.; Serôdio, C.; Almeida, J.; Azevedo, J.; Reis, M.C.Based on cyclic physiologic animal bioimpedance and body temperature a new method is being evaluated to predict estrus in dairy cattle with the aim of improving artificial insemination efficiency. Preceding in-vivo tests are being performed with a dedicated system based on the impedance converter AD5933, and a two-electrode configuration bioimplantable capsule. Acquired results will allow the optimal design of an implantable and autonomous low-power system. The implantable microsystem is being designed and simulated employing low-power techniques in a 0.35μm CMOS standard process.
- EditorialPublication . Bartolo, Paulo; Chua, C.K.In this issue of Virtual and Physical Prototyping, there are three Virtual Prototyping papers and two Physical Prototyping papers. Interestingly, three of the five papers relate to the area of bone tissue engineering, an area which is of great and current research interest to readers.
- Video transcoding from H.264/AVC to MPEG-2 with reduced computational complexityPublication . Moiron, Sandro; Faria, Sergio; Navarro, António; Silva, Vitor; Assunção, PedroThis paper addresses video transcoding from H.264/AVC into MPEG-2 with reduced complexity and high rate-distortion efficiency. While the overall concept is based on a cascaded decoder-encoder, the novel adaptation methods developed in this work have the advantage of providing very good performance in H.264/AVC to MPEG-2 transcoding. The proposed approach exploits the similarities between the coding tools used in both standards, with the objective of obtaining a computationally efficient transcoder without penalising the signal quality. Fast and efficient methods are devised for conversion of macroblock coding modes and translation of motion information in order to compute the MPEG-2 coding format with a reduced number of operations, by reusing the corresponding data embedded in the incoming H.264/AVC coded stream. In comparison with a cascaded decoder-encoder, the fast transcoder achieves computational complexity savings up to 60% with slightly better peak signal-to-noise ratio (PSNR) at the same bitrate.
- Considering application domain ontologies for data miningPublication . Mota Pinto, Filipe; Santos, Manuel FilipeThe dramatically explosion of data and the growing number of different data sources are exposing researchers to a new challenge - how to acquire, maintain and share knowledge from large databases in the context of rapidly applied and evolving research. This paper describes a research of an ontological approach for leveraging the semantic content of ontologies to improve knowledge discovery in databases. We analyze how ontologies and knowledge discovery process may interoperate and present our efforts to bridge the two fields, knowledge discovery in databases and ontology learning for successful database usage projects.
- Aes white paper best practices in network audioPublication . Bouillot, Nicolas; Cohen, Elizabeth; Cooperstock, Jeremy R.; Floros, Andreas; Fonseca, Nuno; Foss, Richard; Goodman, Michael; Grant, John; Gross, Kevin; Harris, Steven; Harshbarger, Brent; Heyraud, Joffrey; Jonsson, Lars; Narus, John; Page, Michael; Snook, Tom; Tanaka, Atau; Trieger, Justin; Zanghieri, UmbertoAnalog audio needs a separate physical circuit for each channel. Each microphone in a studio or on a stage, for example, must have its own circuit back to the mixer. Routing of the signals is inflexible. Digital audio is frequently wired in a similar way to analog. Although several channels can share a single physical circuit (e.g., up to 64 with AES10), thus reducing the number of cores needed in a cable. Routing of signals is still inflexible and any change to the equipment in a location is liable to require new cabling. Networks allow much more flexibility. Any piece of equipment plugged into the network is able to communicate with any other. However, installers of audio networks need to be aware of a number of issues that affect audio signals but are not important for data networks and are not addressed by current IT networking technologies such as IP. This white paper examines these issues and provides guidance to installers and users that can help them build successful networked systems.
- The Higher Moments Dynamic on SIS ModelPublication . Pinto, Alberto; Gouveia Martins, José Maria; Stollenwerk, NicoThe basic contact process or the SIS model is a well known epidemic process and have been studied for a wide class of people. In an epidemiological context, many authors worked on the SIS model considering only the dynamic of the first moments of infecteds, i.e., the mean value and the variance of the infected individuals. In this work, we study not only the dynamic of the first moments of infecteds but also on the dynamic of the higher moments. Recursively, we consider the dynamic equations for all the moments of infecteds and, applying the moment closure approximation, we obtain the stationary states of the state variables. We observe that the stationary states of the SIS model, in the moment closure approximation, can be used to obtain good approximations of the quasi-stationary states of the SIS model.
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