P.A. Bellette

Theoretical & experimental analysis of the Non Markov Parameter to detect low frequency synchronisation in time series analysis

A theoretical investigation into the behaviour of the Non-Markov Parameter is performed from a signal processing perspective in contrast to previous methodologies based on stochastic processes theory. The results indicate that the NMP can be regarded as an informational metric which is indicative of the degree of low frequency synchronisation in a complex system. These results have deep implications for physiological analysis of biological systems where the presence of sychronisation is often a marker of pathological functioning. The NMP measure is then applied to in vivo micro-electrode recordings from the subthalamic nucleus.

Thickness distribution and forming strategy analysis for two point Incremental Forming with a male die

Incremental Sheet Forming (ISF) is a promising sheet-metal-forming technology which is drawing more and more researchers’ attention due to its flexibility of manufacturing three-dimensional products at a relatively low cost for rapid prototyping and small-batch production. This paper is focused on the thickness distribution and the forming strategy analysis for two point incremental forming with a male die. The analyzed benchmark is half a torus which is generated by revolving a semi-circle. Such a part is hardly able to be formed by single point incremental forming because its slope varies from 0 degree to 90 degrees. In terms of the varying slope, the variant of sine’s law is derived to give an approximate prediction of the thickness distribution from an analytical perspective. In addition, a multi-stage forming strategy is proposed in order to form the part successfully. In particular, a keying operation is implemented carefully in order to avoid twist phenomenon and achieve good dimensional accuracy.

Chaotic Signal Analysis of Parkinson's Disease STN Brain Signals

Techniques of signal processing from the field of non-linear time series analysis have been applied to microelectrode recordings from the subthalamic nucleus of patients suffering from Parkinson’s disease. The recordings have been taken while the patients perform different language processing tasks from raw microelectrode recording data obtained from within the brain during surgery. Using classical chaotic signal analysis techniques, very complex behaviour is discerned but no robust trends for different tasks identified. However interesting behaviour is shown when the recordings are analysed using techniques from non-equilibrium statistical mechanics, indicative of different short term signal behaviour whilst performing the different language processing tasks. In particular, the evidence of discrimination between different linguistic tasks and left/right brain behaviour is revealed.