To study the mechanical interactions between heart, lungs and thorax, we propose a mathematical model combining a ventilatory neuromuscular model and a model of the cardiovascular system, as described by Smith et al. 1022616701863)); using a Liénard oscillator, it allows the activity of the respiratory centres, the respiratory muscles and rib cage internal mechanics to be simulated. The minimal haemodynamic system model of Smith includes the heart, as well as the pulmonary and systemic circulation systems. These two modules interact mechanically by means of the pleural pressure, calculated in the mechanical respiratory system, and the intrathoracic blood volume, calculated in the cardiovascular model. The simulation by the proposed model provides results, first, close to experimental data, second, in agreement with the literature results and, finally, highlighting the presence of mechanical cardiorespiratory interactions.
Despite the development of new imaging techniques, existing X-ray data remain an appropriate tool to study speech production phenomena. However, to exploit these images, the shapes of the vocal tract articulators must first be extracted. This task, usually manually realized, is long and laborious. This paper describes a semi-automatic technique for facilitating the extraction of vocal tract contours from complete sequences of large existing cineradiographic databases in the context of continuous speech production. The proposed method efficiently combines the human expertise required for marking a small number of key images and an automatic indexing of the video data to infer dynamic 2D data. Manually acquired geometrical data are associated to each image of the sequence via a similarity measure based on the low frequency Discrete Cosine Transform (DCT) components of the images. Moreover to reduce the reconstruction error and improve the geometrical contour estimation, we perform post-processing treatments, such as a neighborhood averaging and a temporal filtering. The method is applied independently for each articulator (tongue, velum, lips, and mandible). Then the acquired contours are combined to reconstruct the movements of the entire vocal tract. We carry out evaluations, including comparisons with manual markings and with another semi-automatic method.
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