Research fields

Research fields cover a wide disciplinary spectrum from thermodynamics to cognition, encompassing fluid mechanics, energetics, acoustic and voice synthesis, spoken language and text processing, vision, visualisation and perception, virtual and augmented reality. They cover five main scientific domains :

Spoken, written and gestural language processing

A large part of LIMSI research potential is devoted to developing man-machine communication and interaction systems. Part of these systems are based on automatic analysis of both written and spoken language, covering all aspects from signal processing to semantics. Processing of written language concentrates more specifically on information mining from large bodies of heterogeneous documents through the development of question-answer systems. Processing of spoken language deals with automatic transcription of spoken dialogues on various supports, and aims at the identification of locutors, language recognition and identification of emotions. A recent development concerns speech to speech automatic translation with statistical methods. In addition, gesture analysis, related to deaf language, opens news paradigms for man-machine communication.

All three domains need large multi-modal data corpora whose building, testing and evaluation constitutes a research activity in its own, in relation to evaluating the performances of the systems of interaction.

Multimodal perception and interaction

The previous domain results and reciprocally begs for the development of advanced interfaces, combining and blending modalities, for a natural, adaptive, smart interaction. Research in this direction concerns the study, integration and evaluation, in computer systems, of all different possible means of interaction, non only between a man and a machine but also between groups of people through distributed collective networks. Part of these developments begs for advances in fundamental questions on human perception, both visual and audible, in relation with its associated cognitive mechanisms.

Augmented and Virtual Reality

Research in virtual reality at LIMSI is principally oriented towards the additional dimension brought by immersion in the development of new forms and concepts of man-machin interaction. It focuses on multi-modality both in its visual, audio and haptics components. Part of this activity is dedicated at developing augmented reality concepts in relation with medical and artistic applications. Advantage is also taken of the in-house virtual reality facilty to develop applications for immersive CAO through industrial collaborations. Another main objective is the interactive visualization of the huge data sets produced by the modelisation and simulation of large physical systems, like in bio-informatics or fluid mechanics.

Fluid mechanics : instabilities and turbulence

Activities in this field are aimed at comprehending the mechanisms of instability which may take place in the transition from laminar flow states to turbulence, as well as improving the prediction of turbulent flows, in particular of large scale unstationnary structures. These objectives require continuous methodological improvements for the numerical integration of the flow equations, concerning modelling and approximation but also comparison to turbulent achievements. These breakthroughs are used for the treatment and the control of several external and internal flows.

Transfers and energetics

In this field, most of research aims at a better understanding, modelling and ultimately mastering of the heat and mass transfer that takes place between a solid and a fluid. For one part, studies of the elementary or isolated phenomena , such as boiling on a single site or homogenization of periodic porous media, are performed in order to derive their macroscopic properties and hence optimize the systems in which they intervene. In general, the complexity of the situations at hand favor principally experimental investigations, like in micro-scale configurations or kinetics of adsortion where the quality of metrology is essential. In addition, modeling and numerical simulation are developed, like in the growth of isolated vapor bubbles or for the thermodynamical analysis of natural convection in cavities. In parallel, a good deal of efforts go into developing thermoacoustics, both from a technological and scientific standpoint. The technological finality, whose objective is the conception of thermal machines for producing cold at cryogenic temperatures, requires putting together scientific skills, such as in velocity measurements through PIV, thermohydraulic instabilities, conjugate heat transfer in oscillating non-Boussinesq convection or even homogeneization.