Exploration vs Exploitation vs Safety: Risk-averse Multi-Armed Bandits

Motivated by applications in energy management, this paper presents the Multi-Armed Risk-Aware Bandit (MARAB) algorithm. With the goal of limiting the exploration of risky arms, MARAB takes as arm quality its conditional value at risk. When the user-supplied risk level goes to 0, the arm quality tends toward the essential infimum of the arm distribution density, and MARAB tends toward the MIN multi-armed bandit algorithm, aimed at the arm with maximal minimal value. As a first contribution, this paper presents a theoretical analysis of the MIN algorithm under mild assumptions, establishing its robustness comparatively to UCB. The analysis is supported by extensive experimental validation of MIN and MARAB compared to UCB and state-of-art risk-aware MAB algorithms on artificial and real-world problems.Comment: 16 page

Isospin diffusion in semi-peripheral 58Ni^{58}Ni + 197Au^{197}Au collisions at intermediate energies (II): Dynamical simulations

We study isospin effects in semi-peripheral collisions above the Fermi energy by considering the symmetric $^{58}Ni$ + $^{58}Ni$ and the asymmetric reactions $^{58}Ni$ + $^{197}Au$ over the incident energy range 52-74 A MeV. A microscopic transport model with two different parameterizations of the symmetry energy term is used to investigate the isotopic content of pre-equilibrium emission and the N/Z diffusion process. Simulations are also compared to experimental data obtained with the INDRA array and bring information on the degree of isospin equilibration observed in Ni + Au collisions. A better overall agreement between data and simulations is obtained when using a symmetry term which linearly increases with nuclear density

Fuzzy interpolation and level 2 gradual rules

International audienceFunctional laws may be known only at a finite number of points, and then the function can be completed by interpolation techniques obeying some smoothness conditions. We rather propose here to specify constraints by means of gradual rules for delimiting areas where the function may lie between known points. Such an approach results in an imprecise interpolation graph whose shape is controlled by tuning the fuzziness attached to the reference points. However, the graph so-built is still crisp, which means that different possible paths between the interpolation points cannot be distinguished according to their plausibility. The paper discusses a method for introducing membership degrees inside the interpolation graph. The developed formalism relies on the use of weighted nested graphs. It amounts to handling level 2 gradual rules for specifying a family of flexible constraints on the reference points. The proposed approach is compared with the one of extending gradual rules for dealing with type2 fuzzy reference points

Fuzzy Piecewise Linear Regression

International audienceFuzzy regression using possibilistic concepts allows the identification of models from uncertain data sets. However, some limitations still exist about the possible evolution of the output spread with respect to inputs. We present here a modified form of fuzzy linear model whose output can have any kind of output spread tendency. The formulation of the linear program used to identify the model introduces a modified criterion that assesses the model fuzziness independently of the collected data. These concepts are used in a global identification process in charge of building a piecewise model able to represent every kind of output evolution

Fuzzy sensor for the perception of colour

International audienceThe aim of this paper is to propose a new method for building a fuzzy partition on multi-dimensional spaces. This method is apply for creating fuzzy symbolic sensors which use multi-component measurements. Colour sensing is an interesting perception to apply this method. Indeed, men have good control on this sensing but can not explain it simply. Then, the fuzzy colour sensor can learn human perception of colour and does not need explicit information about colour perception mechanisms

Decision Problem of Instrumentation in a Company involved in ISO 50001

International audience—In the context of performance management and the involvement of companies in sustainable development, energy management is a new challenge. Managing energy is a complex problem as it can potentially impact the whole company and if mishandled could be harmful for its added value. In order to assist companies in this challenge, the ISO 50001 proposes a standard for the creation of Energy Management Systems (EnMS). Such systems bring the recurring problem of decision about the choice of the actions necessary into their deployments. Notably, they rely heavily on the data related to the consumptions of energy and its usage in a given company. Hence the problem of decision, at an audit stage, can concern the choice of a sound instrumentation. This paper deals with the interest of the company adixen Vacuum Products in a standard for decision aiding in this situation. The idea is to build the model of preference of the Decision Maker and to establish a generic procedure about decision supported by a MCDA tool. Our proposition is to use the ACUTA method in order to elicit this model of preference

Encoding Seasonal Climate Predictions for Demand Forecasting with Modular Neural Network

Current time-series forecasting problems use short-term weather attributes as exogenous inputs. However, in specific time-series forecasting solutions (e.g., demand prediction in the supply chain), seasonal climate predictions are crucial to improve its resilience. Representing mid to long-term seasonal climate forecasts is challenging as seasonal climate predictions are uncertain, and encoding spatio-temporal relationship of climate forecasts with demand is complex. We propose a novel modeling framework that efficiently encodes seasonal climate predictions to provide robust and reliable time-series forecasting for supply chain functions. The encoding framework enables effective learning of latent representations -- be it uncertain seasonal climate prediction or other time-series data (e.g., buyer patterns) -- via a modular neural network architecture. Our extensive experiments indicate that learning such representations to model seasonal climate forecast results in an error reduction of approximately 13\% to 17\% across multiple real-world data sets compared to existing demand forecasting methods.Comment: 15 page

Distribution en Grece des genres Archanara et Nonagria

Κατά τα έτη 1985, 1988, 1989 και 1990 έγιναν αντίστοιχα τέσσερις επισκοπήσεις διαφόρων υγροβιότοπων στην Ελλάδα, από τη Θράκη μέχρι την Πελοπόννησο, αποβλέπουσες στη μελέτη της γεωγραφικής εξάπλωσης των γενών Archanara και Nonagria (Lepidoptera: Noctuidae). Προνύμφες των Α. geminipuncta και Α. spargami βρέθηκαν σε φυτά Phragmites sp. και Typha sp. από τον ποταμό Εβρο μέχρι τη Λαμία στην Κεντρική Ελλάδα. Το είδος Nonagria typhae βρέθηκε από τον Εβρο μέχρι τη Θεσσαλονίκη καθώς επίσης και στην Εύβοια και Δυτική Πελοπόννησο (Ηλεία). Μόνο ένα έντομο Α. dissoluta συλλέχθηκε κατά τη διάρκεια όλης της έρευνας στο δέλτα του Πηνειού στη Θεσσαλία. Το πιο νότιο όριο εξάπλωσης των τριών κυριότερων ειδών θεωρείται ότι δεν κατεβαίνει χαμηλότερα από τον 39ο παράλληλο. Το όριο αυτό μπορεί να ρυθμίζεται μερικώς από τις μέγιστες θερμοκρασίες του καλοκαιριού. Και τα τρία ανωτέρω είδη αποτελούν νδιάμεσους ξενιστές του παρασίτου των προνυμφών της σεζάμιας και της πυραλίδας του αραβοσίτου, Lydella thompsoni (Diptera, Tachinidae).Quatre prospections faunistiques (1985-1988-1989-1990) on ete realises dans les biotopes humides de la Thrace au Peloponnese: des larves d’ Archanara geminipuncta ont ete collectees dans les roselieres depuis le delta de l’Evrous jusqu’en Grece centrale et occidentale dans 12 stations sur 15. Les especes A. sparganii et N. typhae on ete retrouvees dans le typhetum, depuis le delta de l’Evrous jusqu’a Salonique puis dans l’ile d’Eubιe et le nord du Peloponnese pour la seconde. L’espece A. dissoluta fut collectee en 1 seul exemplaire. La limite meridionale de ces especes en Grece centrale ne parait pas tres eloignιe du 39eme parallele. Leurs distributions sont discutees en fonction des temperatures maximales estivales. Un parasitoοde commun aux 4 especes phytophages, Lydella thompsoni (Diptera: Tachinidae) a ete egalement observe

Isospin diffusion in semi-peripheral 58Ni^{58}Ni + 197Au^{197}Au collisions at intermediate energies (I): Experimental results

Isospin diffusion in semi-peripheral collisions is probed as a function of the dissipated energy by studying two systems $^{58}Ni$ + $^{58}Ni$ and $^{58}Ni$ + $^{197}Au$, over the incident energy range 52-74\AM. A close examination of the multiplicities of light products in the forward part of phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time

Isospin Diffusion in 58^{58}Ni-Induced Reactions at Intermediate Energies

Isospin diffusion is probed as a function of the dissipated energy by studying two systems $^{58}$Ni+$^{58}$Ni and $^{58}$Ni+$^{197}$Au, over the incident energy range 52-74\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 \AM{} is estimated to 130$\pm$10 fm/$c$