SPS-prepared targets for sputtering deposition of phase change films.

Phase-change materials like thin films from the systems [Ge1-xPbx]Te and Ge[Te1-xSex] are of interest for data storage. For these compositions amorphous materials can not be obtained by melt quenching. However, Suitable films can be obtained using RF sputtering. Spark plasma sintering (SPS) was used to densify the powders to obtain large targets. Synthesis conditions and characterisations of the targets are reported. Amorphous nano films were obtained using the sintered targets and characterised

The pilot dimension method: Reconciling Steering and Conformity in Workshops

International audienceIn machining workshops, workpieces are produced according to dimensions known as manufacturing dimensions. For the same workpiece and the same manufacturing plan, several sets of manufacturing dimensions can be used but none satisfy simultaneously the two main missions workshops need to fulfil: (a) Ensuring conformity of products to their design dimension tolerances (also called blueprint tolerances) and (b) steering machines in order to compensate for tool wear. The set of manufacturing dimensions obtained from the design dimensions using the minimal chain of dimensions method is optimal for a conformity check of workpieces but is practically unusable for steering machines because of the complexity of its relationships toward the tool correctors and tools dimensions. The pilot dimensions method consists in, on the one hand, identifying and representing these tool correctors and these tool/program dimensions on the production drawings (besides the manufacturing dimensions) and, on other the other hand, determining their correction values through a mathematical set of relations after having measured the manufacturing dimensions on a workpiece. Doing so will strongly reduce adjustment time, reduce the number of workpieces used for adjustments and greatly enhance the quality of workpiece batches

Mono inverter dual parallel PMSM - Structure and Control strategy

This paper presents a dual parallel connected PMSM fed by a single power inverter. Both motors have to respect the synchronism even if they have different load torque. The rotor position of the two motors that is to say the load applied on each motor are consequently permanently compared. The motor with the highest load is set as the master one and is auto-piloted. The other one which has the same applied voltage has the same electric pulsation and so the same speed rotation. The change of the master choice is done whereas the load applied on the machine is changing so that oscillations appear during this change. The steady state is however rapidly attained and the synchronism stays always observed

Mono inverter multi-parallel permanent magnet synchronous motor:structure and control strategy

This study presents a new and original Mono inverter multi-parallel permanent magnet synchronous motor (PMSM) system. To obtain the stability of such a system, each of the motor synchronisms should always be respected regardless of their load torque. In this case, only one motor, called ‘master motor’, will be self-piloted. If the chosen master motor is the one with the highest applied load torque, synchronism is respected for each of the motors. To find this machine, a solution that compares the rotor positions is thus developed. Experimental results are given for a system with two PMSM plugged in parallel. The proposed solution can, however, be applied to systems whatever the motor numbers; therefore additional simulations are provided for a four-PMSM system

Microgreffage de quatre espèces ligneuses sahéliennes (Acacia senegal, Faidherbia albida, Tamarindus indica et Ziziphus mauritiana) en vue de leur rajeunissement

Cette note décrit une méthodologie de rajeunissement pour quatre ligneux sahéliens: Acacia senegal, Faidherbia albida, Tamarindus indica, Ziziphus mauritiana. Elle a consisté à prélever stérilement un expiant mesurant 5-10 mm et à le microgreffer sur un jeune plant élevé in vitro. Les principaux facteurs de réussite sont l'âge du porte-greffe (de deux à six semaines selon l'espèce), le niveau de greffage (sur hypocotyle plutôt que sur épicotyle) et la nature du greffon (les apex ont une meilleure réactivité que les noeuds axillaires). La méthode a été appliquée au rajeunissement d'arbres adultes. Le critère de rejuvénilisation retenu est l'aptitude à l'enracinement des microboutures prélevées sur le greffon. L'effet rajeunissant du microgreffage dépend de l'espèce, du mode de mobilisation des premières copies végétatives et du nombre de cycle de microgreffages. Chez F albida dont la mobilisation des sujets adultes est réalisée par bouturage de racines, un tiers des microboutures s'enracinent après un seul cycle et 75% après un second. Pour Z. mau ritiana mobilisé par greffage horticole, un quart des microboutures prélevées sur les greffons a réacquis l'aptitude à l'enracinement après deux cycles de microgreffage. Aucun enracinement n'est constaté pour A. senegal et T. indica mobilisés par bouturage horticole. (Résumé d'auteur