Thierry Hervé

Monitoring behavior in home using a smart fall sensor and position sensors

The authors developed a system for remotely monitoring human behavior during daily life at home, to improve the security and the quality of life. The activity was monitored through infrared position sensors and magnetic switches. For the falls detection the authors had to develop a smart sensor. The local communications were performed using RF wireless links to reduce the cabling and to allow mobility of the person. An application software performs data exploitation locally but it also performs remote data transmission through the network. This project aim at expanding the telecare solution to a larger population of elderly people who are presently forced to live in hospices.

Asymptotic Behavior of Neural Networks and Image Processing

We give in this paper the definition of a formal network and after, some information about the use of its asymptotic properties for segmenting 3D images reconstructed from parallel cross sections (such as those from Computed Tomography or Magnetic Resonance Imaging). The huge size of data makes algorithmic complexity and storage requirements the key points of 3D edge detection. The classical approach consists in computing the gradient by applying an operator which enhances the grey gradient. Most of all these operators are 3D generalization of 2D edge detectors : Roberts[1], Hueckel[2], Prewitt [3], Canny[4],[5],[6], Marr and Hildreth[7],[8] operators. A critical problem of many of these detectors concerns the size of the convolution masks used to implement the operator : small kernel are noise sensitive, but large ones need prohibitive computing times. A solution is to realize an optimal filter with recursive filters [5],[6].

Neural network in the auditory system: Influence of the temporal context on the response represented by a random field

A model of a neural network of the auditory system is presented; it is based on the representation of the temporal activity of N fibers by a random field defined on a finite set. Our simulations show the behavior of the network in response to different stimuli; we investigate the duration of the transient times of the output random field and establish the link between these durations and a context effect. The results are consistent with the characteristics of a speech signal, and we could compare some of them to typical perceptive measures made on stop consonnants.

A new stimulation strategy for recording electrical auditory evoked potentials in cochlear implant patients

Recording electrical auditory brainstem responses (EABR) provides clinical insight about responses of the residual post-cochlear neural system to electrical stimulation in profoundly deaf patients. A new strategy is presented for stimulating patients already implanted with a 15-electrode cochlear implant. Since the device is fully re-programmable via a RS-232 PC interface, it was possible to load a specific stimulating strategy designed to improve the spatial locus and the temporal structure of the impulse stimulation. Waves III to V emerge more clearly when this method is applied.