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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.
- Pulse transit time estimation for continuous blood pressure measurement: a comparative studyPublication . Duarte, Diana; Lopes, Nuno Vieira; Fonseca-Pinto, Rui
- A Review of Wearable Sensor Patches for Patient MonitoringPublication . Santos, Sónia; Guarino, Maria Pedro; Neves, Sandra; Lopes, Nuno VieiraWearable sensor patches are potent tools for patient monitoring in hospital care, with a particular focus on the Emergency Department waiting areas. They can enhance patient safety by alerting healthcare professionals to abnormal changes in vital physiological signals. Wearable sensors have been shown to be useful in monitoring patients’ vital signs continuously and in real-time in emergency rooms. However, there are still some challenges that need to be addressed before they can be widely adopted in emergency rooms. Some of these challenges include sensor stability with minimized signal drift, on-body sensor reusability, and long-term continuous health monitoring. This paper reviews wearable sensor patches that have the potential for use in hospital patient monitoring, considering the key variables monitored in emergency rooms. Eligible patches must be wearable, present at least one approval (CE or FDA), and measure more than one physiological parameter.
- Hierarchical fuzzy logic based approach for object trackingPublication . Lopes, Nuno Vieira; Couto, Pedro M.; Jurio, Aranzazu; Melo-Pinto, PedroIn this paper a novel tracking approach based on fuzzy concepts is introduced. A methodology for both single and multiple object tracking is presented. The aim of this methodology is to use these concepts as a tool to, while maintaining the needed accuracy, reduce the complexity usually involved in object tracking problems. Several dynamic fuzzy sets are constructed according to both kinematic and non-kinematic properties that distinguish the object to be tracked. Meanwhile kinematic related fuzzy sets model the object's motion pattern, the non-kinematic fuzzy sets model the object's appearance. The tracking task is performed through the fusion of these fuzzy models by means of an inference engine. This way, object detection and matching steps are performed exclusively using inference rules on fuzzy sets. In the multiple object methodology, each object is associated with a confidence degree and a hierarchical implementation is performed based on that confidence degree.
- Fuzziness measure approach to automatic histogram thresholdPublication . Lopes, Nuno Vieira; Bustince, Humberto; Filipe, Vitor; Melo-Pinto, PedroIn this paper, an automatic histogram threshold approach based on a fuzziness measure is presented. This work is an improvement of an existing method. Using fuzzy logic concepts, the problems to find a minima of a criterion function are avoided. Similarity between gray levels is the key to find an optimal threshold. Two initial regions of gray levels, located at the boundaries of the histogram, are defined. Then, using an index of fuzziness, a similarity process is started to find the threshold point. A significant contrast between objects and background is assumed. Previous histogram equalization is used in small contrast images. No prior knowledge of the image is required.
- Fuzzy logic based approach for object feature trackingPublication . Lopes, Nuno Vieira; Melo-Pinto, Pedro; Couto, Pedro M.This thesis introduces a novel technique for feature tracking in sequences of greyscale images based on fuzzy logic. A versatile and modular methodology for feature tracking using fuzzy sets and inference engines is presented. Moreover, an extension of this methodology to perform the correct tracking of multiple features is also presented. To perform feature tracking three membership functions are initially defined. A membership function related to the distinctive property of the feature to be tracked. A membership function is related to the fact of considering that the feature has smooth movement between each image sequence and a membership function concerns its expected future location. Applying these functions to the image pixels, the corresponding fuzzy sets are obtained and then mathematically manipulated to serve as input to an inference engine. Situations such as occlusion or detection failure of features are overcome using estimated positions calculated using a motion model and a state vector of the feature. This methodology was previously applied to track a single feature identified by the user. Several performance tests were conducted on sequences of both synthetic and real images. Experimental results are presented, analysed and discussed. Although this methodology could be applied directly to multiple feature tracking, an extension of this methodology has been developed within that purpose. In this new method, the processing sequence of each feature is dynamic and hierarchical. Dynamic because this sequence can change over time and hierarchical because features with higher priority will be processed first. Thus, the process gives preference to features whose location are easier to predict compared with features whose knowledge of their behavior is less predictable. When this priority value becomes too low, the feature will no longer tracked by the algorithm. To access the performance of this new approach, sequences of images where several features specified by the user are to be tracked were used. In the final part of this work, conclusions drawn from this work as well as the definition of some guidelines for future research are presented.
- Multi-feature Tracking Approach Using Dynamic Fuzzy SetsPublication . Lopes, Nuno Vieira; Couto, Pedro; Melo-Pinto, PedroIn this paper a new tracking approach based in fuzzy concepts is introduced. The aim of this methodology is to incorporate in the proposed model the uncertainty underlying any problem of feature tracking, through the use of fuzzy sets. Several dynamic fuzzy sets are constructed according both cinematic (movement model) and non cinematic properties (image gray levels) that distinguish the feature. Meanwhile cinematic related fuzzy sets model the feature movement characteristics, the non cinematic fuzzy sets model the feature visible image related properties. The tracking task is performed through the fusion of these fuzzy models by means of a fuzzy inference engine. This way feature detection and matching steps are performed exclusively using inference rules on fuzzy sets.
- Blood pressure assessment during standard clinical manoeuvres: A noninvasive PPT based approachPublication . Duarte, Diana; Lopes, Nuno Vieira; Fonseca-Pinto, RuiContinuous and reliable blood pressure (BP) monitoring during standard clinical manoeuvres provides important information about the cardiovascular system condition. Common invasive methods are accurate but denote increased risk. An alternative approach is based on changes in pulse transit time (PTT) defined as the time delay between the R-wave of the electrocardiogram (ECG) and the peak value of the photoplethysmogram (PPG) signal at the same cardiac cycle.
- Development of a mixed-meal that impacts carotid-body mediated cardiorespiratory and metabolic parameters - a pilot studyPublication . Frazão, Ana; Costa, Andreia; Teixeira, Bárbara; Santo, Marisa; Brito, Gabriel; Lages, Marlene; Lopes, Nuno Vieira; Fonseca-Pinto, Rui; Pereira, Cidália; Guarino, Maria PedroThe carotid bodies (CB) have been recently implicated in the genesis of metabolic diseases in animal models. The CBs respond to circulating insulin to increase heart rate, respiratory rate and blood glucose levels. In humans, this mechanism is not well characterized.
- Avaliação de sistemas posturais da pélvis numa pessoa com Distrofia Muscular do tipo Cinturas: resultados da análise a três almofadas na promoção do equilíbrio dinâmicoPublication . Marques, Cíntia; Matos, Carolina; Cavaleiro, Joana; Simões, Juliana; Fonseca-Pinto, Rui; Lopes, Nuno; Ribeiro, Jaime MoreiraIntrodução: As almofadas anti-escaras são dispositivos especializados para a redistribuição de pressão e gestão da carga sobre os tecidos e do microclima. Devem manter o alinhamento postural, facilitar o movimento, criar uma base estável, aliviar a dor e serem confortáveis. Podem ser compostas exclusivamente por um material como espuma, gel, ar e fluido, ou pela combinação de dois ou mais destes materiais. As investigações concretizadas focam-se na distribuição do peso e negligenciam o comportamento dinâmico da almofada durante as atividades quotidianas. Objetivos: Avaliar a eficácia na manutenção do equilíbrio dinâmico de três tipos de almofadas de gama média-alta com diferentes composições. Métodos: Estudo com uma pessoa do sexo feminino com Distrofia Muscular do tipo Cinturas, utilizando-se: uma almofada de espuma e ar (A), uma almofada de espuma e bolsa de fluido (B) e uma de ar (C). A recolha de dados foi realizada em dois momentos: 1)recolha dados antropométricos, cinemáticos e dinâmicos, através de medição direta do alcance, videogravação e acelerómetro, e pressões exercidas sobre as almofadas, mediante um protocolo de movimentos e randomização de almofadas; 2)avaliação da perceção do utilizador com questionário e escala visual analógica de dor, após quatro horas de permanência na almofada. Resultados: A almofada A revelou melhores resultados ao nível do alcance máximo, do pico de pressão na posição inicial, do coeficiente de variação e da pressão média na flexão frontal do tronco. A almofada B apresentou resultados mais positivos na área de contacto, coeficiente de variação e na pressão média na posição inicial, no pico de pressão da flexão frontal do tronco, na variação da aceleração e na análise subjetiva. Conclusão: As almofadas anti-escaras que, na sua composição, combinam dois materiais, são mais eficazes na promoção do equilíbrio dinâmico, observando-se vantagem na utilização da almofada composta por espuma e fluido.