Network emulation focusing on QoS-Oriented satellite communication

This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

The QoSxLabel: a quality of service cross layer label

A quality of service cross layer label

Adaptive Replication in Distributed Content Delivery Networks

We address the problem of content replication in large distributed content delivery networks, composed of a data center assisted by many small servers with limited capabilities and located at the edge of the network. The objective is to optimize the placement of contents on the servers to offload as much as possible the data center. We model the system constituted by the small servers as a loss network, each loss corresponding to a request to the data center. Based on large system / storage behavior, we obtain an asymptotic formula for the optimal replication of contents and propose adaptive schemes related to those encountered in cache networks but reacting here to loss events, and faster algorithms generating virtual events at higher rate while keeping the same target replication. We show through simulations that our adaptive schemes outperform significantly standard replication strategies both in terms of loss rates and adaptation speed.Comment: 10 pages, 5 figure

Investigations of Zr(IV) in LiF-CaF2: stability with oxide ions and electroreduction pathway on inert and reactive electrodes

In this work, a detailed electrochemical study of the molten LiF-CaF2-ZrF4 system is provided in the 810-920°C temperature range, allowing the determination of the reduction potential, the diffusion coefficient and the reduction mechanism of dissolved Zr(IV) on an inert Ta electrode. Addition of CaO in the molten salt is shown to cause Zr(IV) precipitation into a mixture of solid compounds, most likely ZrO2 and ZrO1.3F1.4. Underpotential deposition of Zr on Cu and Ni electrodes is also evidenced

Nitrogen evolution as anodic reaction in molten LiF–CaF2

The electrochemical behaviour of nitride ions has been studied in fluoride melts (eutectic LiF-CaF2) by cyclic voltammetry and square wave voltammetry. The purpose of this work is to propose an alternative way for anodic reaction in molten fluorides processes. Thermodynamical analysis can be used for the evaluation of the anodic material regarding to its oxidation potential and reactivity with nitrogen. Then electrochemical investigations confirm the oxidation of nitride ions into nitrogen in a one-step process exchanging 3 electrons, and let propose several materials usable for nitrogen evolving

Electrochemical extraction of europium from molten fluoride media

This work concerns the extraction of europium from molten fluoride media. Two electrochemical ways have been examined: (i) the use of a reactive cathode made of copper and (ii) the co-deposition with aluminium on inert electrode, leading to the formation of europium-copper and europium-aluminium alloys respectively, as identified by SEM-EDS analysis. Cyclic voltammetry and square wave voltammetry were used to identify the reduction pathway and to characterise the step of Cu-Eu and Al-Eu alloys formation. Then, electrochemical extractions using the two methodologies have been performed with extraction efficiency around 92 % for copper electrode and 99.7 % for co-reduction with aluminium ions

Exponential map and L∞L_\infty algebra associated to a Lie pair

In this note, we unveil homotopy-rich algebraic structures generated by the Atiyah classes relative to a Lie pair $(L,A)$ of algebroids. In particular, we prove that the quotient $L/A$ of such a pair admits an essentially canonical homotopy module structure over the Lie algebroid $A$, which we call Kapranov module.Comment: 7 page

Lanthanides extraction processes in molten fluoride media. Application to nuclear spent fuel reprocessing

This paper describes four techniques of extraction of lanthanides elements (Ln) from molten salts in the general frame of reprocessing nuclear wastes; One of them is chemical: the precipitation of Ln ions in insoluble compounds (oxides or oxifluorides); the others use electrochemical methodology in molten fluorides for extraction and measurement of the progress of the processes: first electrodeposition of pure Ln metals on an inert cathode material was proved to be incomplete and cause problems for recovering the metal; electrodeposition of Ln in the form of alloys seems to be far more promising because on one hand the low activity of Ln shifts the electrodeposition potential in a more anodic range avoiding any overlapping with the solvent reduction and furthermore exhibit rapid process kinetics; two ways were examined: (i) obtention of alloys by reaction of the electroreducing Ln and the cathode in Ni or preferably in Cu, because in this case we obtain easily liquid compounds, that enhances sensibly the process kinetics; (ii) codeposition of Ln ions with aluminium ions on an inert cathode giving a well defined composition of the alloy. Each way was proved to give extraction efficiency close to unity in a moderate time