Electrocaloric effect in Ba(0.2)Ca(0.8)Ti(0.95)Ge(0.05)O(3) determined by a new pyroelectric method

The present letter explores the electrocaloric effect (ECE) in the lead free oxide Ba0.8Ca0.2Ti0.95Ge0.05O3 ceramics (BCTG). The electrocaloric responsivity (dT/dE) was determined by two different methods using the Maxwell relationship (dT/dE)~(dP/dT)_E. In a first well-known indirect method, P-E hysteresis loops were measured in a wide temperature range from which the pyroelectric coefficient p_E=(dP/dT)_E and thus (dT/dE) were determined by derivation of P(T,E) data. In the second novel method the pyroelectric coefficient p_E and consequently the electrocaloric responsivity was determined by direct measurements of the pyroelectric currents under different applied electric fields. Within the experimental error good agreement was obtained between two methods with an electrocaloric responsivity equal to 0.18 +/- 0.05 10-6 K.m.V-1 was obtained at about 410 KComment: 5 pages, 4 figure

An Agent-based Distributed Scheduling for Military Logistics

International audienceThere has been a significant increase in the improvement of response to disasters in crisis management supply chain. Due to their sudden occurrence, these disasters require a consequent quick and efficient response that depends on the ability of logistics systems to generate plans under a variety of constraints. The supply chain studied in this work is a crisis management supply chain, composed of several elements such as transportation means, loading units, suppliers, equipment, resources, persons... We propose an innovative method for solving a distributed delivery scheduling problem, based on a multi-agent system, for the delivery of goods (food, water, clothes, etc.) to the areas affected by the disaster. The covered areas are geographically distributed and partitioned into multiple sub-regions. Each area is assigned a delivery scheduling sub problem. By employing a distributed cooperative framework, we achieved an incorporation of various evaluation parameters in the process of scheduling in order to maintain a high level of synchronization of all the supply chain, and so to insure a better response to the crisis

Protocoles de négociation à base d'agents communicants pour une chaine logistique de gestion de crise

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An innovative tool based on multi-agent approach for the Crisis management

International audienceAchieving effective logistic requires nowadays a dynamic multi-functional information system capable of sharing real time data with users and actors dispersed anywhere. To meet this challenge, we propose in this paper a tool for crisis management based on autonomous software components. Our automated logistic simulator seeks the sustainment of needs and the monitoring of the flows of resources. In our work we show different slices of a very complex and distributed supply chain: the crisis management supply chain. The demonstrated sides include inventory management, sourcing and communication protocols. We show how the operational and logistics interactions would occur in case of crisi

Generic need estimating agents for crisis management

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PAAN: Partial Agreement Negotiation Network based on Intelligent Agents in Crisis Situation

International audienceThe aim of this paper is to present a multi-agent based approach for negotiation in crisis management. We propose to harness the potential of the multi-agent system (MAS) technology for constructing a framework of cooperation agents that are capable of delivering an optimal solution for crisis. Supply Chain study is adopted more and more for the companies' competitiveness development. Our industrial partner EADS (European Aeronautic Defence and Space Company) handles a logistic flows demonstrator for crisis management, developed by our research team. A Multi-Agent architecture is planned to design a distributed supply chain. In this paper, we propose to adopt an advanced interaction between the autonomous entities. Therefore, we propose a multi agent based architecture for crisis management supply chain. A new form of negotiation is presented to avoid, in a crisis situation, the stock-out by balancing the resources provisions throughout the system

A need estimating agent-based tool for resources forecasting

International audienceThe management and optimization of the crisis management supply chain is very complex and involves multiple concepts: supply resources, probability and statistics, means of transportation, disturbances on the delivery dates, and the importance of decisions involving human lives. To meet these requirements, multi-agent systems are a well-suited solution for modeling the supply chain through interactive autonomous entities. Our model represents a distributed logistic system in which flows of resources are hierarchically forwarded from one zone to another, taking into account the randomness of resources' consumption. The issue is then to optimize the procurement policy to avoid shortages that could cripple the whole system. In this paper we propose the multi-agent technology for modeling the different actors of the logistic chain. Then we propose an innovative method to estimate the future needs in resources for every zone. Our forecasting method is based on fuzzy calculations combined to ARMAX time series modelling. The objective of our work is to avoid, in a crisis situation, stock outs by optimizing the estimation of the future needs in resources for each zone and balancing the flows throughout the syste

Logistics flow scheduling in distributed crisis management supply chain

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A Preventive anticipation model for crisis management supply chain

International audienceIn the military, agile and robust military supply chains are key in providing timely responses to support operations in theatre. Supply during peacetime can be managed by proactive logistics plans and classic supply chain management techniques to guaranty the availability of required needs. However, in case of perturbations (time of war, natural disasters...) the need for support increases dramatically and logistics plans need to be adjusted rapidly. To do that, we propose to use anticipation mechanisms. An anticipator uses a world model to construct future predictions about the supply chain and checks whether an undesirable state may be reached. If it is the case, the anticipator adapts his behavior to avoid the actions responsible of this state. In this paper, we focus on the use of anticipation in multi-agent coordination for military logistic planning. We propose de formalize preventive anticipation in the context of a Crisis Management Supply Chain (CMSC)

Ferroelectric phase changes and electrocaloric effects in Ba(Zr0.1_{0.1}Ti0.9_{0.9})1−x_{1-x}) Snx_xO3_3 ceramics solid solution

International audienceThe effect of tin (Sn) incorporation in lead-free Ba(Zr$_{0.1}$Ti$_{0.9}$)O$_3$ ceramics was investigated. Single phases with perovskite structure were identified using X-ray diffraction analysis. Dielectric permittivity and pyroelectric current measurements carried out versus temperature revealed ferroelectric-to-paraelectric structural phase transitions showing intermediate ferroelectric-to-ferroelectric sequence anomalies for low Sn-content compounds. Electrocaloric effects were highlighted by recording P$-$E hysteresis loops as function of temperature and the electrocaloric temperature change $\Delta$T = 0.2 K was evaluated under 8.7 kV cm$^{-1}$ applied electric field. Electrocaloric responsivity of 0.23 K mm kV$^{-1}$ near Curie temperature remained almost constant until x = 0.075 before decreasing for compounds with $x \geq$ 0.1. Basing on pyroelectric measurement, we highlight the presence of one quadruple point in this system where the simultaneous presence of Zr and Sn in BaTiO$_3$ matrix seems to stabilize ferroelectric and electrocaloric behaviors instead of Sn element alone