Scattering defect in large diameter titanium-doped sapphire crystals grown by the Kyropoulos technique

International audienceThe Kyropoulos technique allows growing large diameter Ti doped sapphire for Chirped pulse amplification laser. A scattering defect peculiar to Kyropoulos grown crystals is presented. This defect is characterized by different techniques: luminescence, absorption measurement, X-ray rocking curve. The impact of this defect to the potential application in chirped pulse amplification CPA laser is evaluated. The nature of this defect is discussed. Modified convexity of the interface is proposed to avoid the formation of this defect and increase the quality of the Ti sapphire crystal

Developing a corpus of strategic conversation in The Settlers of Catan

International audienceWe describe a dialogue model and an implemented annotation scheme for a pilot corpus of annotated online chats concerning bargaining negotiations in the game The Settlers of Catan. We will use this model and data to analyze how conversations proceed in the absence of strong forms of cooperativity, where agents have diverging motives. Here we concentrate on the description of our annotation scheme for negotiation dialogues, illustrated with our pilot data, and some perspectives for future research on the issue

S-FMECA Based Collaborative Design Proposal for Additive Manufacturing Methodology

In the current context, the sustainable development, eco-design and eco-manufacturing concepts are being developed in research laboratories, and further being integrated gradually into manufacturing industries. Hence, the needed information for eco-design is scattered throughout the product life cycle and is not centralized; especially when designing for Additive Manufacturing. This paper aims to develop a collaborative eco-design methodology by using eco-design tools in different design stages and, finally, to contribute to tackling this issue. Either in the early design stage or in the detailed on, the designer will be supported to make sustainable, conscious decisions. The proposed methodology based on the sustainable-failure modes, effects, and criticality analysis (S-FMECA) eco-designing tool allows the communication with computer-aided design (CAD), computer-aided manufacturing (CAM), life cycle assessment (LCA), topology optimization (TO) and product life cycle management (PLM) software in order to assist the designer to make green-conscious decisions

Indirect techniques for astrophysical reaction rates determinations

Direct measurements of nuclear reactions of astrophysical interest can be challenging. Alternative experimental techniques such as transfer reactions and inelastic scattering reactions offer the possibility to study these reactions by using stable beams. In this context, I will present recent results that were obtained in Orsay using indirect techniques. The examples will concern various astrophysical sites, from the Big-Bang nucleo synthesis to the production of radioisotopes in massive stars

S-FMECA: A Novel Tool for Sustainable Product Design - Additive Manufacturing

The choices made in the early design stage (EDS) will largely define the environmental impacts of a product. The purpose of this paper is to develop an eco-design method used for assessing semi-quantitatively the sustainability of an additively manufactured product since the EDS. This article presents a semi-quantitative method to support EDS-conscious environmental decisions. A novel Sustainable-Failure Mode, Effect, and Criticality Analysis (S-FMECA) tool is developed to support designers in the conceptual design phase, to guide the choices, and to provide a valuable evaluation of the future additively manufactured product. Through the integration of the environmental aspects in FMECA analysis, systematic prevention of errors, and enhancement of sustainability since the EDS would be the main advantage of this tool

Auger electronic spectroscopy and electrical characterisation of InP(100) surfaces passivated by N2 plasma

International audienceAuger electron spectroscopy (AES) was used to investigate the processes taking place during the initial stages of InP(100) surfaces nitridation. This AES study combined with electrical measurements (intensity-potential) shows that the processes greatly differ depending on the nitridation angles. Results show that with grazing angle for nitrogen flow, the nitridation process is more efficient. Results obtained with AES spectra are coherent with electrical measurements : Hg/InN/InP(100) Schottky diodes present better electrical characteristics in the case of a grazing flow. That means, the adsorption of nitrogen on the surface is more important for this configuration

Al0.2Ga0.8As solar cells monolithically grown on Si and GaAs by MBE for III-V/Si tandem dual-junction applications

Al0.2Ga0.8As photovoltaic solar cells have been monolithically grown on silicon substrates by Molecular Beam Epitaxy. Due to the 4% lattice mismatch between AlGaAs and Si, Threading Dislocations (TDs) nucleate at the III-V/Si interface and propagate to the active region of the cells where they act as recombination centers, reducing the performances of the devices. In order to reduce the Threading Dislocation Density (TDD) in the active layers of the cells, InAlAs Strained Layer Superlattice (SLS) Dislocation Filter Layers (DFLs) have been used. For one of the samples, in-situ Thermal Cycle Annealing (TCA) steps have additionally been performed during growth. For comparison purposes, reference Al0.2Ga0.8As solar cells have been grown lattice-matched on GaAs. For the sample grown on Si without TCA, the TDD has been reduced from over 7×109cm-2 at the III-V/Si interface to 3×107cm-2 in the base of the cells. With TCA, the TDD has been reduced throughout the sample from over 3×109cm-2 in the initial epilayers to 8(±2)×106cm-2 in the base of the cells. For the best devices, the Voc improves from 833mV on Si without TCA to 895mV using TCA, compared with 1070mV for the reference sample grown lattice-matched on GaAs. Similarly the fill factor improves from 73.7% on Si without TCA to 74.8% using TCA, compared with 78.4% on GaAs. The high bandgap-voltage offset obtained both on Si and GaAs indicates a non-optimal bulk AlGaAs material quality due to non-ideal growth conditions

Coexistence of spin canting and metamagnetism in a one-dimensional Mn(II) compound bridged by alternating double end-to-end and double end-on azido ligands and the analog co(II) compound

Metals in Catalysis, Biomimetics & Inorganic Material

On the similarity of Sturm-Liouville operators with non-Hermitian boundary conditions to self-adjoint and normal operators

We consider one-dimensional Schroedinger-type operators in a bounded interval with non-self-adjoint Robin-type boundary conditions. It is well known that such operators are generically conjugate to normal operators via a similarity transformation. Motivated by recent interests in quasi-Hermitian Hamiltonians in quantum mechanics, we study properties of the transformations in detail. We show that they can be expressed as the sum of the identity and an integral Hilbert-Schmidt operator. In the case of parity and time reversal boundary conditions, we establish closed integral-type formulae for the similarity transformations, derive the similar self-adjoint operator and also find the associated "charge conjugation" operator, which plays the role of fundamental symmetry in a Krein-space reformulation of the problem.Comment: 27 page