In this paper, the viscoplastic regularization method is used to simulate strain localization in a compressed prismatical sample of Fontainebleau sandstone. First of all, the limits of Rice's formalism concerning the prediction of the localization band width and the post-bifurcation treatment are recalled. Then the theoretical aspects of the viscoplastic regularization method is reviewed. The non-objectivity or mesh-sensitivity of the solution is pointed out when a simple plastic model without viscosity is used. Finally, a fictitious viscosity parameter in the form of relaxation time is introduced in the model and regularizes the problem.

Forward solution studies have been performed using a cellular automata computer model. This computational procedure has been applied to simulate cardiac tissue activation and its corresponding magnetic field generated has been calculated. The propagation pattern associated with different mechanisms of atrial flutter arrhythmia has been simulated. For each simulated pattern of propagation, one has investigated the effect on the magnetic field generated, produced by the introduction of a conduction inhomogeneity due to a slow-pathway. This latter represents the site of successful ablation in the treatment of atrial flutter. The analysis of different computational images obtained allowed one to characterize the possibility of identification of regions of slow conduction in the simulated cardiac tissues.

A method founded on the follow-up of an electromagnetic cavity resonant frequency working round 390 MHz has been carried out in order to measure the void rates of bubble field induced by a 308 kHz ultrasonic cavitation in liquids. This method can detect void rates as low as 2 × 10−5. The experimental set up permits to study the influence of some experimental parameters on the void rate, such as the acoustic power, the acoustic irradiation duration, and the dissolved gas concentration in the liquid. Moreover, an estimation of the bubble size distribution is obtained. The extension of the method to open resonators and the possibility to observe the fast evolutions of the void rate are considered.

We have developed a new prototype of microwave radiometric imaging devoted to the measurement of the temperature inside a dissipative media. The main application we are looking for, is the non-invasive thermometry of human tissues. We obtain quite satisfactory results in the early characterisation of breast tumours in terms of malignancy or benignity. We have, at this moment in progress, a clinical evaluation of patients that gives good results at an intermediary stage. To improve the spatial resolution, we have developed an inversion process based on a regularisation method in the spatial frequency domain, associated with a Deriche filter for threshold extraction. We show that this process is well suited to our problem and can be applied to clinical images for a quantitative retrieval of the temperature.

The first aircraft experiment with the wide-angle airborne laser ranging system has been conducted in May 1998 over a small network of 1 km2, equipped with 64 cube-corner retroreflectors. The ranging system was operated from a research aircraft (ARAT, Fokker 27) at an altitude of 1 km. Data have been collected during two 4-hour flights. The paper describes the data processing methods and presents the first results from this experiment. A precision of 2 cm has been achieved on the difference of vertical coordinates from two sets of ~ 3000 distance measurements. Results are consistent with simulations and a posteriori covariance. A drastic data sorting for outliers, due to strong overlap of reflected echoes, has been necessary. Hence, the actual number of measurements and the positioning precision became relatively small. Higher precision is expected in future experiments, once the instrument's link budget will be improved.