Antilogic

This paper is an interim report of joint work begun in (Castelnérac & Marion 2009) on dialectic from Parmenides to Aristotle. In the first part we present rules for dialectical games, understood as a specific form of antilogikê developed by philosophers, and explain some of the key concepts of these dialectical games in terms of ideas from game semantics. In the games we describe, for a thesis A asserted by the answerer, a questioner must elicit the answerer’s assent to further assertions B1, B2,…, Bn, which form a scoreboard from which the questioner seeks to infer an impossibility (adunaton); we explain why the questioner must not insert any of his own assertions in the scoreboard, as well as the crucial role the Law of Non Contradiction, and why the games end with the inference to an impossibility, as opposed to the assertion of ¬A. In the second part we introduce some specific characteristics of Eleatic Antilogic as a method of enquiry. When Antilogic is used as a method of inquiry, then one must play not only the game beginning with a given thesis A, but also the game for ¬A as well as for A & ¬A, while using a peculiar set of opposite predicates to generate the arguments. In our discussion we hark back to Parmenides’ Poem, and illustrate our points with Zeno’s arguments about divisibility, Gorgias’ ontological argument from his treatise On Not-Being, and the second part of Plato’s Parmenides. We also identify numerous links to Aristotle, and conclude with some speculative comments on the origin of logic

Chaînes logistiques et modèles d'affaires du commerce électronique<br />Le cas de la vente en ligne de produits informatiques

Une version remaniée de ce texte a été publiée dans la Revue Française de Gestion 2003/2 - n° 143, pages 95 à 110:http://www.cairn.info/article.php?ID_REVUE=RFG&ID_NUMPUBLIE=RFG_143&ID_ARTICLE=RFG_143_0095International audienceLe commerce en ligne de produits informatiques apparaît comme une activité en cours de structuration dans laquelle il est difficile de dégager des modèles d'affaires stables et d'en évaluer la performance. Les pratiques des sites de commerce électronique sont variées et plusieurs logiques d'agencement des supply chain existent: certaines font de l'industrialisation des process le principal moteur de la performance et standardisent au maximum les mécanismes de coordination à l'intérieur de la chaîne, d'autres optent pour des solutions plus adaptables et des mécanismes de coordination plus souples permettant d'offrir une plus grande variété de solutions au client final, enfin, d'autres restent dans une logique du « coup par coup » et font de la gestion de chaque commande une activité spécifique, sans être pour autant sanctionnés par le marché compte tenu de la faiblesse des coûts fixes qu'ils supportent. Il subsiste donc dans ce secteur beaucoup de petites structures.L'étude montre qu'aborder le commerce électronique à travers les questions logistiques permet de sortir l'analyse du e-commerce du discours sur la « nouveauté radicale » ou « l'entreprise virtuelle ». Elle montre en effet que les commerçants en ligne ne peuvent pas échapper aux questions classiques du commerce que sont: le stock, la gamme, la mise à disposition du client, la nature des relations avec leurs partenaires (coopératives, concurrentielles...). Ces quelques variables clefs structurent en profondeur les supply chain comme les modèles d'affaires des commerçants en ligne. La manière dont chaque site agence ces ressources de base traduit la compétence centrale sur laquelle s'appuie le site pour créer de la valeur. Trois types de modèles d'affaires sont ainsi repérés: ceux s'appuyant sur une compétence de type industriel, ceux s'appuyant sur une compétence de type marchande et enfin une dernière mixant les compétences des deux premiers modèles

Study of bond between epoxy, steel reinforcing bars and concrete affected by alkali-silica reaction

Installation of drilled-in epoxy bonded reinforcing barsis generally an effective strengthening method for deficient concretestructures. However, this method of rehabilitation has largely been studied and tested on sound concrete elements, i.e. without any pathological damage, which raisesthe question of bond capabilities inexisting damaged elements. This investigation studies the influence of alkali-silica reaction (ASR) onthe capacity of epoxy bonded anchors. ASR, which is very common in eastern Canada, results from the chemical reaction between the alkali hydroxides in the concrete’s pore solution and some siliceous mineral phases inthe aggregates. Pull-out tests on epoxy bonded anchors havingembedded lengths offourtimes the bar diameter(Ø= 16 mm)have demonstrated a drop in bond strength when concrete is affected by ASR. In addition, the study revealed that the progression of concrete expansion due to ASR, leads to a confinement of the epoxy bonded anchor and increases the bond strength. These conclusions are therefore considered for the development of a model for the design of epoxy bonded anchors in existing concrete infrastructure affected by ASR

A new versatile in-process monitoring system for milling

International audienceTool condition monitoring (TCM) systems can improve productivity and ensure workpiece quality, yet, there is a lack of reliable TCM solutions for small-batch or one-off manufacturing of industrial parts. TCM methods which include the characteristics of the cut seem to be particularly suitable for these demanding applications. In the first section of this paper, three process-based indicators have been retrieved from literature dealing with TCM. They are analysed using a cutting force model and experiments are carried out in industrial conditions. Specific transient cuttings encountered during the machining of the test part reveal the indicators to be unreliable. Consequently, in the second section, a versatile in-process monitoring method is suggested. Based on experiments carried out under a range of different cutting conditions, an adequate indicator is proposed: the relative radial eccentricity of the cutters is estimated at each instant and characterizes the tool state. It is then compared with the previous tool state in order to detect cutter breakage or chipping. Lastly, the new approach is shown to be reliable when implemented during the machining of the test part

Angular approach combined to mechanical model for tool breakage detection by eddy current sensors

International audienceThe paper presents a new complete approach for Tool Condition Monitoring (TCM) in milling. The aim is the early detection of small damages so that catastrophic tool failures are prevented. A versatile in-process monitoring system is introduced for reliability concerns. The tool condition is determined by estimates of the radial eccentricity of the teeth. An adequate criterion is proposed combining mechanical model of milling and angular approach. Then, a new solution is proposed for the estimate of cutting force using eddy current sensors implemented close to spindle nose. Signals are analysed in the angular domain, notably by synchronous averaging technique. Phase shifts induced by changes of machining direction are compensated. Results are compared with cutting forces measured with a dynamometer table. The proposed method is implemented in an industrial case of pocket machining operation. One of the cutting edges has been slightly damaged during the machining, as shown by a direct measurement of the tool. A control chart is established with the estimates of cutter eccentricity obtained during the machining from the eddy current sensors signals. Efficiency and reliability of the method is demonstrated by a successful detection of the damage

Flexible Storage of Still Images with a Perceptual Quality Criterion

International audienceThe purpose of the paper is to introduce a new method for flexible storage of still images. The complete design of the system is described with the scalable encoding, the distortion computation, the bits allocation strategy, and the method for the memory management. The main improvement is the full exploitation of a perceptual metric to assess precisely the introduced distortion when removing a layer in a scalable coding stream. Experimental results are given and compared with a system which uses the PSNR as distortion metric

Flexible Differentiable Optimization via Model Transformations

We introduce DiffOpt.jl, a Julia library to differentiate through the solution of optimization problems with respect to arbitrary parameters present in the objective and/or constraints. The library builds upon MathOptInterface, thus leveraging the rich ecosystem of solvers and composing well with modeling languages like JuMP. DiffOpt offers both forward and reverse differentiation modes, enabling multiple use cases from hyperparameter optimization to backpropagation and sensitivity analysis, bridging constrained optimization with end-to-end differentiable programming. DiffOpt is built on two known rules for differentiating quadratic programming and conic programming standard forms. However, thanks ability to differentiate through model transformation, the user is not limited to these forms and can differentiate with respect to the parameters of any model that can be reformulated into these standard forms. This notably includes programs mixing affine conic constraints and convex quadratic constraints or objective function