A Strong Call-By-Need Calculus

We present a call-by-need ?-calculus that enables strong reduction (that is, reduction inside the body of abstractions) and guarantees that arguments are only evaluated if needed and at most once. This calculus uses explicit substitutions and subsumes the existing strong-call-by-need strategy, but allows for more reduction sequences, and often shorter ones, while preserving the neededness. The calculus is shown to be normalizing in a strong sense: Whenever a ?-term t admits a normal form n in the ?-calculus, then any reduction sequence from t in the calculus eventually reaches a representative of the normal form n. We also exhibit a restriction of this calculus that has the diamond property and that only performs reduction sequences of minimal length, which makes it systematically better than the existing strategy. We have used the Abella proof assistant to formalize part of this calculus, and discuss how this experiment affected its design

Pondération d'automates obtenus par alignements partiels de séquences protéiques

National audienceL'identification de la fonction d'une protéine à partir de sa séquence d'acides aminés est un enjeu majeur en bioinformatique. Pour répondre à ce défi, l'équipe Dyliss a proposé un modèle statistique pour caractériser des familles fonctionnelles de protéines nommé protomate, un automate pondéré construit à partir d'un multiple alignement partiel et local d'un échantillon d'apprentissage de séquences : chaque colonne de chaque alignement partiel et local est associée à un état dans le protomate. Actuellement, le poids d'un état est calculé en prenant en compte seulement la colonne dont il est issu, mais du fait de la partialité de l'alignement, cette colonne ne contient pas toutes les séquences de l'échantillon d'apprentissage. Nous proposons ici une modification du calcul de ces poids qui prend en compte les séquences protéiques de l'échantillon qui ne passent pas dans la colonne. De plus, un protomate calcule pour une séquence un score d'appartenance à la famille qu'il modélise qui repose sur la comparaison de la probabilité que la séquence appartienne à la famille selon le protomate avec la probabilité d'appartenance selon un modèle aléatoire. Cependant la distribution de ce modèle n'était pas calculée de manière homogène au calcul de l'appartenance selon le protomate, nous avons donc proposé une modification de ce modèle de sorte à rendre les deux calculs plus cohérents

Modelling a Multi-Modal Logistic Network with Agents and Dynamic Graphs

International audienceThis paper presents a model of a logistic system. Our goal is to understand how such a system (with numerous stakeholders) behaves and evolves according to different constraints or scenarios. We adopted a complex system approach which leads us to propose an agent-based model coupled with dynamic graphs. It allows us to represent the properties, constraints and behaviours at a local level of a logistic system in order to reproduce the global behaviours thanks to the simulation in a dynamic context. The simulation (which uses data about the Seine axis) allows to test different scenarios in order to understand how local decisions impact the whole system. For example, this work presents the evolution of the system at the opening of the Seine-Nord Europe Canal. Indeed, this canal is a real major project for Europe, and has numerous economical stakes. So, we first describe the traffic evolution on the multi-modal transportation network (see figures 1 to 4). Then, we observe different other measures (evolution of costs, transportation mode share). Thanks to these analyses, we show that the Seine-Nord Europe Canal should promote the use of the river barges and reduce financial costs. In the same time, it could modify the respective shares of the northern European ports

A strong call-by-need calculus

We present a call-by-need $\lambda$-calculus that enables strong reduction (that is, reduction inside the body of abstractions) and guarantees that arguments are only evaluated if needed and at most once. This calculus uses explicit substitutions and subsumes the existing strong-call-by-need strategy, but allows for more reduction sequences, and often shorter ones, while preserving the neededness. The calculus is shown to be normalizing in a strong sense: Whenever a $\lambda$-term t admits a normal form n in the $\lambda$-calculus, then any reduction sequence from t in the calculus eventually reaches a representative of the normal form n. We also exhibit a restriction of this calculus that has the diamond property and that only performs reduction sequences of minimal length, which makes it systematically better than the existing strategy. We have used the Abella proof assistant to formalize part of this calculus, and discuss how this experiment affected its design. In particular, it led us to derive a new description of call-by-need reduction based on inductive rules

A new method of probing mechanical losses of coatings at cryogenic temperatures

A new method of probing mechanical losses and comparing the corresponding deposition processes of metallic and dielectric coatings in 1-100 MHz frequency range and cryogenic temperatures is presented. The method is based on the use of extremely high-quality quartz acoustic cavities whose internal losses are orders of magnitude lower than any available coatings nowadays. The approach is demonstrated for Chromium, Chromium/Gold and a multilayer tantala/silica coatings. The ${\rm Ta}_2{\rm O}_5/{\rm Si}{\rm O}_2$ coating has been found to exhibit a loss angle lower than $1.6\times10^{-5}$ near 30 {\rm MHz} at 4 {\rm K}. The results are compared to the previous measurements

Effets de la variation spatiale et temporelle des propriétés des terrains sur les défaillances des réseaux enterrés

Les interactions entre la nappe phréatique peu profonde et les réseaux d assainissement sont en général très complexes. Dans le but d étudier l impact des variations du niveau de la nappe phréatique sur les dégradations des conduites, un modèle hydrogéologique numérique tridimensionnel (3D) de la nappe phréatique ayant un aquifère multicouche au sein d une zone de 83 km2 de l agglomération bordelaise (Mérignac, Pessac, Talence) a été développé, calibré et validé. Pour ce faire, un modèle conceptuel de cet aquifère multicouche a dans un premier temps été défini sur la base des descriptions lithostratigraphiques des forages. Puis un travail géostatistique a été entrepris pour construire les limites des formations géologiques et les cartes piézométriques issues de campagnes de mesures de hauteurs d eau de la nappe phréatique. Nous avons par la suite développé une méthodologie originale de transformation de l information lithologique au droit des sondages en perméabilités, puis en champs de perméabilités en utilisant des méthodes géostatistiques. Dans un second temps, les conditions hydrogéologiques ont été simulées en utilisant le logiciel Visual Modflow . Les paramètres hydrogéologiques ont été calibrés manuellement et automatiquement sur la base des niveaux d eau mesurés lors des campagnes de juillet 2010, octobre 2010 et mars 2011. La validation du modèle qui s est effectuée en simulant les cotes piézométriques au pas mi-décadaire allant de juin 1993 à mai 2012 montre que les chroniques piézométriques observées sur les 35 piézomètres du domaine étudié sont correctement restituées et la dynamique de la nappe phréatique est reproduite. Dans un dernier temps, les distributions spatiales et temporelles des cotes piézométriques simulées ont permis d identifier les zones d ennoiement des réseaux d assainissements en comparant les cotes piézométriques aux cotes des réseaux. Ces zones d ennoiement ont été comparées aux principaux secteurs de casses de canalisations. Les secteurs de casses de canalisations sont localisés dans les zones à faible probabilité d ennoiement des conduites. L environnement naturel hydrogéologique pris comme paramètre isolé ne constitue donc pas un facteur explicatif au phénomène de casses des canalisations.The interactions between shallow groundwater and sewer network are generally complex. The aim of this research is to study the impact of the water table level variation on the damages of the buried pipes. For this purpose, a three-dimensional (3D) numerical groundwater flow model of the shallow multi-aquifer of the Bordeaux urban area, within a 83 km2 area (Mérignac, Pessac, Talence), is developed, calibrated and validated. In order to do this, in a first step, a conceptual model was built based on stratigraphic descriptions of the boreholes. A geostastistical study was carried out to build the limits of the geological layers and the piezometrical maps from the measurement campaigns of water table levels. Then, an original methodology to transform the description of lithological units to local hydraulic conductivity values is proposed and the reconstruction of hydraulic conductivity fields at the urban scale was performed based on geostatistical methods. In a second step, hydrogeological conditions were simulated using the finite-difference groundwater flow model MODFLOW-2005 (Visual Modflow ). The hydrogeological parameters were then calibrated manually and automatically based on water table elevation data measured in July 2010, October 2010 and March 2010. The model validation covered 6890 days, from June 1993 to may 2012. The results showed that the simulated heads are quite accurate and reproduce the main dynamics of the system at 35 piezometers. The spatial and temporal distribution of the heads of the piezometers simulated permitted to identify the flooding zones of the sewer network by comparing the piezometric head with the altitude of the networks. The sectors where the pipes are damaged were localized in the zone wherein there is low probability of flooding. Additionally, the natural hydrologic environment, taken as a sole factor, cannot explain the pipe breakage phenomena.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Distributional Reinforcement Learning with Unconstrained Monotonic Neural Networks

The distributional reinforcement learning (RL) approach advocates for representing the complete probability distribution of the random return instead of only modelling its expectation. A distributional RL algorithm may be characterised by two main components, namely the representation and parameterisation of the distribution and the probability metric defining the loss. This research considers the unconstrained monotonic neural network (UMNN) architecture, a universal approximator of continuous monotonic functions which is particularly well suited for modelling different representations of a distribution (PDF, CDF, quantile function). This property enables the decoupling of the effect of the function approximator class from that of the probability metric. The paper firstly introduces a methodology for learning different representations of the random return distribution. Secondly, a novel distributional RL algorithm named unconstrained monotonic deep Q-network (UMDQN) is presented. Lastly, in light of this new algorithm, an empirical comparison is performed between three probability quasimetrics, namely the Kullback-Leibler divergence, Cramer distance and Wasserstein distance. The results call for a reconsideration of all probability metrics in distributional RL, which contrasts with the dominance of the Wasserstein distance in recent publications

Investigations on Partial Discharges risk in aeronautical rotating machine fed by HVDC 540Vdc network

The voltage level aboard new aircraft generations has grown from 115V AC to 230V AC . This has given rise to a new HVDC +/- 270V instead of +270V. The Adjustable Speed Drives (ASD) aboard more electrical aircraft are currently fed by fast switching PWM IGBT converters which rise time and fall time are higher than 50ns. To improve the converters power density, the very fast Wide Bandgap semiconductor technologies (Silicon Carbide) are currently under evaluation; their switching rise time and fall time could be lower than 20ns. This paper, by using industrial ASD fed by 540Vdc, initially addresses an experimental investigations analysis of motor overvoltages according to: inverters technologies (IGBT and SiC), harness length and harness shielding. Then, investigations on the Partial Discharges Inception Voltage (PDIV) are carried out on primary components of Electrical Insulation System (EIS) type 1 at atmospheric and reduced pressures, according to several parameters: magnet wire (MW) diameter, MW grade, polyimide insulating paper thickness. The paper concludes with a discussion of the different results and thoughts about overvoltages and partial discharges challenges