Disruption Management Optimization for Military Logistics

Part 3: Financial and Management Applications of AIInternational audienceTo ensure long-term competitiveness, companies try to maintain a high level of agility, flexibility and responsiveness. In many domains, hierarchical SCs are considered as dynamic systems that deal with many perturbations. In this paper, we handle a specific type of supply chain: a Crisis Management Supply Chain (CMSC). 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. Subjective variables like risk, uncertainty and vulnerability will be used in conjunction with objective variables such as inventory levels, delivery times and financial loss to determine preferred courses of action

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

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

Structural investigation, dielectric, ferroelectric, and elecrocaloric properties of lead-free Ba(1-x)CaxTi(1-x)(Li1/3Nb2/3)(x)O3-delta (x=0.02 and x=0.07) ceramics

International audienceThe ferroelectric lead-free Ba(1-x)CaxTi(1-x)(Li1/3Nb2/3)(x)O3- with x=0.02 and x=0.07 (BCLNTO2 and BCLNTO7) ceramics were elaborated by a conventional sintering process. The effects of Ca and (Li, Nb) contents in the BTO matrix on the structure, dielectric, ferroelectric and electrocaloric properties were investigated. The refinement of the structure at room temperature showed that both BCLNTO2 and BCLNTO7 ceramics crystallize in the tetragonal system. Ferroelectric and dielectric investigations revealed the presence of three phase transitions similar to the parent phase BTO. Applying the Maxwell relation, the electrocaloric temperature changes were calculated using P-E hysteresis loops adjusted at different temperatures. The electrocaloric responsivity was found (max) (T/E)=0.14K mm/kV at T-ECmax = 374 and (max)=0.12K mm/kV at T-ECmax= 302K for BCLNTO2 and BCLNTO7, respectively

Structural investigation, dielectric, ferroelectric, and elecrocaloric properties of lead-free Ba(1−x)CaxTi(1−x)(Li1/3Nb2/3)xO3−δ (x = 0.02 and x = 0.07) ceramics

International audienc

Indirect and direct electrocaloric measurements of (Ba1-xCax)(Zr0.1Ti0.9)O-3 ceramics (x=0.05, x=0.20)

International audienceElectrocaloric effect in lead-free (Ba1-xCax) (Zr0.1Ti0.9)O-3 ceramics (with x = 0.05 and x = 0.20) has been investigated by using two different indirect methods. In the first classic approach, the electrocaloric temperature change (Delta T) was calculated from the Maxwell relation based on measured P-E hysteresis loops recorded at different temperatures. In the second approach, the Delta T was calculated from the Maxwell relation based on pyroelectric current measurements. The advantage of such approach is that it enables direct determination of the pyroelectric coefficient, which should be otherwise calculated from the hysteresis loops in the classic approach. Direct method was finally used for verification of the obtained results. Good agreement between methods was found near the cubic-to-tetragonal phase transition temperature with a significant electrocaloric responsivity of Delta T/Delta E = 0.30 K mm/kV for the composition x = 0.05 obtained by direct method. (c) 2016 Elsevier B.V. All rights reserved

Sequence of structural transitions and electrocaloric properties in (Ba1-xCax)(Zr0.1Ti0.9)O-3 ceramics

International audienceThe influence of the incorporation of Calcium in lead-free ferroelectric Ba(Zr0.1Ti0.9)O-3 perovskite on its structural phase transition, dielectric, pyroelectric, ferroelectric, and electrocaloric effect was investigated. Room temperature X-ray diffraction study allowed the identification of a continuous solid solution in the composition range 0 <= x <= 20 mol% with a rhombohedral to orthorhombic structural transition beyond 15mol%. Structural investigation of X-ray diffraction as a function of temperature reveals four different structural regions for the compositions with low content of Ca and three regions for the compositions with high Ca-content. Using heat flow measurements and dielectric investigations, two sequences of structural phase transitions were elucidated. The tetragonal-to- orthorhombic and orthorhombic-to-rhombohedral phase transitions induced by temperature variation were found to decrease with the increase of the Ca2+ content, while the cubic-to-tetragonal phase transition temperature remained almost unchanged and exhibited a dielectric permittivity maximum observed around the composition of x = 15mol%. The electrocaloric temperature change Delta T was calculated from two methods: the thermal variation of P-E hysteresis loops and pyroelectric current. The highest electrocaloric Delta T/DE = 0.24 K mm/kV was found for the composition x = 0.05. The largest electrocaloric responsivity around 0.30 K mm/kV was observed for this composition at Curie temperature using direct method. (C) 2017 Elsevier B.V. All rights reserved