Télé-opération : servomécanismes maître-esclave

Objectif Le projet consistait en la réalisation d’un système de téléopération ‘maître et esclave’ communiquant via le réseau Profibus. On propose de télé-manipuler un robot bilatéral à l’aide d’un joystick. Les données à transmettre de manière bidirectionnelle sont la position et le couple des moteurs. Le matériel utilisé sera le même que celui employé durant le projet de semestre. Résultats Le design choisis pour le robot a été inspiré de celui de la grue. Il est commandé par un joystick ou le retour de force a été réalisé à l’aide d’un moteur à courant continu sur un joystick industriel. Le système est enfin visualiser par un PC avec le logiciel Intouch.Ziel Das Ziel des Projekts war einer Telemanipulation Meister – Sklave zu realisieren. Sie tauschen die Informationen über ein Profibus Netzwerk aus. Die Informationen sind die Lage und das Drehmoment. Die Ausrüstung ist die gleiche wie beim Semester. Resultate Was für den Roboter gewählte Design ähnelt dem eines Krans. Er wird mit einen Joystick gesteuert. Man kann mit einem Motor das Drehmoment fühlen. Man kann das System auch sehen mit dem programm Intouch auf ein computer

Keyboards as a New Model of Computation

We introduce a new formalisation of language computation, called keyboards. We consider a set of atomic operations (writing a letter, erasing a letter, going to the right or to the left) and we define a keyboard as a set of finite sequences of such operations, called keys. The generated language is the set of words obtained by applying some non-empty sequence of those keys. Unlike classical models of computation, every key can be applied anytime. We define various classes of languages based on different sets of atomic operations, and compare their expressive powers. We also compare them to rational, context-free and context-sensitive languages. We obtain a strict hierarchy of classes, whose expressiveness is orthogonal to the one of the aforementioned classical models. We also study closure properties of those classes, as well as fundamental complexity problems on keyboards

Clustering in Cell Cycle Dynamics with General Response/Signaling Feedback

Motivated by experimental and theoretical work on autonomous oscillations in yeast, we analyze ordinary differential equations models of large populations of cells with cell-cycle dependent feedback. We assume a particular type of feedback that we call Responsive/Signaling (RS), but do not specify a functional form of the feedback. We study the dynamics and emergent behaviour of solutions, particularly temporal clustering and stability of clustered solutions. We establish the existence of certain periodic clustered solutions as well as "uniform" solutions and add to the evidence that cell-cycle dependent feedback robustly leads to cell-cycle clustering. We highlight the fundamental differences in dynamics between systems with negative and positive feedback. For positive feedback systems the most important mechanism seems to be the stability of individual isolated clusters. On the other hand we find that in negative feedback systems, clusters must interact with each other to reinforce coherence. We conclude from various details of the mathematical analysis that negative feedback is most consistent with observations in yeast experiments.Comment: To appear in J. Theoretical Biology 292 (2012), 103-11

Colour maps for fisheries acoustic echograms

Echograms are used to visualize fisheries acoustic data, but choice of colour map has a significant effect on appearance. Quantitative echograms should use colour maps, which are colourful (have a perceived variety and intensity of colours), sequential (have monotonic lightness), and perceptually uniform (have consistency of perceived colour contrast over their range). We measure whether colour maps are colourful (⁠Mˆ(3)>0⁠), sequential (⁠rs=±1⁠), and perceptually uniform (ρ = 1) using an approximately perceptually uniform colour space (CIELAB). Whilst all the fisheries acoustic colour maps tested are colourful, none is sequential or perceptually uniform. The widely used EK500 colour map is extremely colourful (⁠Mˆ(3)=186⁠), not sequential (⁠rs=0.06⁠), and has highly uneven perceptual contrast over its range (⁠ρ=0.26⁠). Of the fisheries acoustic colour maps tested, the Large Scale Survey System default colour map is least colourful (⁠Mˆ(3)=79⁠), but comes closest to being sequential (⁠rs=−0.94⁠), and perceptually uniform (⁠ρ=0.95⁠). Modern colour maps have been specifically designed for colour contrast consistency, accessibility for viewers with red-green colour-blindness, and legibility when printed in monochrome, and may be better suited to the presentation and interpretation of quantitative fisheries acoustic echograms