HAL Portal UPHF (Université Polytechnique Hauts-de-France)
Not a member yet
28473 research outputs found
Sort by
AI-based multimodal ICF classification: application to Alzheimer disease
No full textInternational audienceAI-based multimodal ICF classification: application to Alzheimer diseas
A robust nonsingular Fixed-Time Controller: Application to Robot Manipulators
No full textInternational audienceSliding Mode Control (SMC) techniques allow accurate position tracking, where fixed-time stability has become an area of great interest. A kind of systems which has represented a control challenge for the last decades are robot manipulators due to their highly nonlinear dynamics and the presence of external perturbations. The current contribution introduces a novel singularity free fixed-time SMC scheme for position and velocity tracking of robot manipulators in the presence of external perturbations. The design of the controller and the sliding surface together improves transient performance by avoiding the presence of high-peaks, providing a natural saturation of the control input while at the same time reducing chattering effects. The result holds globally when the robot model is fully known and locally when this is not the case (partially known or completely unknown). Simulation results confirm the effectiveness and the performance improvement of the developed theory with respect to other well-known schemes
Nonlinear modeling of AlN/GaN HEMT accounting for self-biasing effect during RF step stress: analysis and hard-SOA
No full textplateforme PROOF LAASInternational audienceIn this study, we investigate the non-linear (NL) behavior of AlN/GaN HEMT technologies under gain compression when submitted to 10 GHz single-tone RF-step stress, which is crucial for millimetre-wave power application robustness. We evaluate AlN/GaN transistors, targeting high-power amplifiers with operating frequency above 30 GHz. We present here an original method that includes, in a unique NL expression, the varying self-biasing effect caused by RF step-stress sequences. This methodology can be used as a tool for comparative analysis of technological variants and various transistor geometries post RF stress. The step-stresses are conducted on HEMT in saturated mode and in diode operation alone, to assess the electrical origins of defects and the critical Safe Operating Area (SOA) of these devices. We identify the mechanism of failure as stemming from the degradation of the Schottky gate when subjected to critical RF power levels, due to its constrained capacity to handle power signals exceeding 18 dBm. Furthermore, we highlight the remarkable RF robustness of this technology, achieving gain compression of around 10 dB without degradation
Bioinspired recognition of cricket calling songs in sub-nanowatt inter-pulse delay detector
No full textInternational audienceAbstract Energy efficiency is one of the main concerns in the design of embedded circuits, especially considering the ever-growing amount of portable devices produced for specialized to everyday life applications. Taking inspiration from neuronal processes in the brain, neuromorphic systems are seen as promising solutions to this concern. Great advances in all fields led to the production of numerous hardware implementations, digital or mixed-signal for the most part. While digital systems showcase high accuracy performances and an advanced technological maturity, they fail to reach the ultra-low power consumptions of emerging technologies or fully analog implementations due to generally non-dedicated chips and bulky hardware. In this work, we designed and implemented a bioinspired analog demonstrator of inter-pulse delay detection on standard complementary metal oxide semiconductor in the subthreshold operation mode. Relying on the temporal pattern recognition mechanism in female field crickets, our circuit reach on average 750 pW of total power consumption under probes during detection on real-world recordings of male crickets calling song. The circuit was evaluated in quiet, noisy, and multi-source environments, demonstrating strong detection performances given its sparse architecture and ultra-low power consumption
Dynamiques des recherches en sciences de l'information et de la communication.: Information - Communication : Défis contemporains 4ème édition révisée
No full textInternational audienceIn the digital age and media upheavals, information and communication sciences (ICS) are an essential disciplinary field to decipher the transformations of our societies. This collective work, the result of the work of the Permanent Conference of Directors of CIS research units explores the recent dynamics that drive this field in full effervescence.Over the course of its three parts: Journalism, information, media; Images, cinema, audiovisual media and cultural industries; Public and political communication, it presents the work of the units and their researchers to answer three questions, in the continuity of previous editions: what are the major themes of the work conducted by researchers in information and communication sciences? What research and publications are representative of the discipline? What are their contributions to a better knowledge of contemporary societies? A stimulating dive into the debates, practices and innovations that shape our media and political world.Book written and edited by the Permanent Conference of Directors of Research Units in Information and Communication Sciences.À l’ère du numérique et des bouleversements médiatiques, les sciences de l’information et de la communication (SIC) s’imposent comme un champ disciplinaire essentiel pour décrypter les transformations de nos sociétés. Cet ouvrage collectif, fruit des travaux de la Conférence permanente des directeurs et directrices des unités de recherche en SIC explore les dynamiques récentes qui animent ce domaine en pleine effervescence.Au fil de ses trois parties : Journalismes, informations, médias ; Images, cinéma, médias audiovisuels et industries culturelles ; Communication publique et politique, il présente les travaux des unités et de leurs chercheur·e·s pour répondre à trois questions, dans la continuité des éditions précédentes : quelles sont les thématiques majeures des travaux conduits par les chercheur·e·s en sciences de l’information et de la communication ? Quelles sont les recherches et les publications représentatives de la discipline ? Quels sont leurs apports à une meilleure connaissance des sociétés contemporaines ? Une plongée stimulante au cœur des débats, des pratiques et des innovations qui façonnent notre monde médiatique et politique.Ouvrage rédigé et édité par la Conférence permanente des directeurs·trices des unités de recherche en sciences de l’information et de la communication
Modelling of the influence of measurement uncertainties on the algorithmic complexity of 3D topography stitching
No full textInternational audienceObservation of physical phenomena and their expression on solids is a challenge, especially considering their coupling. As a privileged place of interaction between solids and the external environment, surface should be studied. Roughness analysis often relies on optical profilometers to provide detailed topographic maps of the solid. To facilitate the analysis of physical phenomena, multiscale analysis is used to separate each phenomenon at their scale of application. However, optical profilometers natively propose a limited scale range to observe. Stitching is an assembling technique of topographic map solving this problem, by generating high resolution over a large field of measurement. Stitching can be summed up as an optimization problem of the alignment of elementary maps, i.e., registration. Yet, the stitching optimization problem is not trivial to solve. This paper proposes a theoretical analysis of the algorithmic complexity of the stitching problem and provides an estimation of the stitching problem complexity, considering measurement uncertainties, which is lacking from literature. First, a simplified stitching problem is presented, based on the assumption that stitching in standard conditions is at least as algorithmically complex. Simulations of local stitching displacements are performed based on the simplified stitching problem. Modelling of stitching reveals that the stitching problem is in exponential time problem class. The complexity of the simplified stitching problem is then estimated to follow an evolution similar to 2^n by a theoretical analysis of the stitching problem complexity
Microstreaming pour la propulsion de micronageurs artificiels acoustiques
No full textPression de radiation, streaming, dynamique de bulles; GAPSUS - Acoustique Physique, Sous-Marine et Ultra-SonoreNational audienceLe développement de micro-nageurs artificiels a suscité un intérêt croissant durant ces dernières années. En effet, un nageur entièrement manœuvrable permettrait diverses applications \emphin vitro et même \emphin vivo telles que des thérapies ultra ciblées ou des opérations de microchirurgie. À l’opposé de la plupart d’autres types de nageurs, l’excitation acoustique permet une propulsion biocompatible en utilisant une source d’énergie découplée du nageur mobile. Il a été récemment montré (Kaynak et al. Lab Chip (2017)) qu’il est possible de propulser un nageur entièrement solide avec des ondes acoustiques, mais les mécanismes sous-jacents sont encore mal compris et une manœuvrabilité 3D d’un tel nageur n’a pas encore été réalisée. Ici, nous étudions un écoulement appelé \emphstreaming, qui est un écoulement moyen non-linéaire induit par les vibrations rapides du nageur, généralement considéré comme mécanisme principal de propulsion. Pour comprendre les détails physiques de cet écoulement, nous étudions le streaming autour d’une micropoutre en tant que modèle simplifié d’une queue de nageur. Expérimentalement, nous observons différents motifs de streaming que nous pouvons corréler aux déformations de la micropoutre afin d’en déduire les paramètres importants. De plus, les résultats expérimentaux sont comparés à des nouveaux modèles analytiques qui permettent une compréhension plus fine des mécanismes sous-jacents. Ces conclusions sont une étape importante envers la compréhension des mécanismes de propulsion plus complexes d’un micronageur acoustique entier et, sur le moyen terme, sa manœuvrabilité 3D
Spectral Colour Changes: A Promising Parameter for Smart Dew Retting Monitoring Solutions
No full textNatural fibres from plants such as flax (Linum usitatissimum) are gaining interest as possible green replacements of synthetic fibres to reduce textile pollution footprints. However, the extractionfacilitating process of bast fibres from the flax stem, i.e. dew retting, is still empirically evaluated, resulting in either over or under retted fibre, both of which decrease the resulting fibre quality and introduce batches variability. There is currently no "in-the-field" efficient device available for farmers to monitor retting of straws. Expert farmers generally use a 'Fried-test', a manual colour marking method, to define dew retting progress. In our study, we have objectively measured this optical colourchange evaluation using a portable spectrophotometer to acquire spectral data. In this work, spectra in 400 to 700 nm range were acquired during 3 retting campaigns, carried out in different retting years, involving 4 fields in total. Cluster analysis of all the spectra showed that retting could be divided into 4 distinct phases of stem decolouration (assigned as Beginning, Early, Middle and Advanced). Moreover,</div
MULTIPLE SOLUTIONS AND SIMULATIONS FOR AN ION FLOW FIELD PROBLEM APPLIED TO HVDC TRANSMISSION LINES
No full textThis paper initiates a mathematical investigation of a PDE model for the transport of high voltage direct current via overhead lines. We prove the existence of infinitely many solutions, give necessary conditions for existence, explicitly compute the continuum of all radial solutions, and develop a new numerical algorithm for this problem