A Compilation Flow for Parametric Dataflow: Programming Model, Scheduling, and Application to Heterogeneous MPSoC

International audienceEfficient programming of signal processing applications on embedded systems is a complex problem. High level models such as Synchronous dataflow (SDF) have been privileged candidates for dealing with this complexity. These models permit to express inherent application parallelism, as well as analysis for both verification and optimization. Parametric dataflow models aim at providing sufficient dynamicity to model new applications, while at the same time maintaining the high level of analyzability needed for efficient real life implementations. This paper presents a new compilation flow that targets parametric dataflows. Built on the LLVM compiler infrastructure, it offers an actor based C++ programming model to describe parametric graphs, a compilation front-end providing graph analysis features, and a retargetable back-end to map the application on real hardware. This paper gives an overview of this flow, with a specific focus on scheduling. The crucial gap between dataflow models and real hardware on which actor firing is not atomic, as well as the consequences on FIFOs sizing and execution pipelining are taken into account.The experimental results illustrate our compilation flow applied to compilation of 3GPP LTE-Advanced demodulation on a heterogeneous MPSoC with distributed scheduling features. This achieves performances similar to time-consuming hand made optimizations

Cyclic Voltammetry of La0.78Sr0.2FeO3-d and La0.78Sr0.2Co0.2Fe0.8O3-d Electrodes Interfaced to CGO/YSZ

The electrochemical characteristics of La0.78Sr0.2FeO3-delta (L78SF) and La0.78Sr0.2Co0.2Fe0.8O3-delta (L78SCF) cathode electrodes interfaced to a double layer Ce0.8Gd0.2O2-delta (CGO)/YSZ electrolyte were studied using cyclic voltammetry, in the temperature range of 600 to 850 degrees C and under flow of 0.7% O-2 in He. The aim was to identify the electrochemical processes taking place under cathodic polarization. Current peaks were observed in the voltammograms, corresponding to potential and currents dependent on scan rate and temperature. The observed cathodic peaks can be related to reduction of the iron or/and cobalt ions but also to the competing reaction of oxygen reduction. (c) 2008 Elsevier B.V. All rights reserved

Synthesis and characterization of doped apatite-type lanthanum silicates for SOFC applications

A series of iron- and/or aluminium-doped apatite-type lanthanum silicates (ATLS) La9.83Si6-x-yAlxFeyO26 +/-delta (x = 0, 0.25, 0.75, and 1.5, y = 0, 025, 0.75, and 1.5) were synthesized using the mechanochemical activation (MA), solid state reaction (SSR), Pechini (Pe) and sol-gel (SG) methods. The total conductivity of the prepared materials was measured under air in the temperature range 600-850 degrees C using 4-probe AC impedance spectroscopy. Its dependence on composition, synthesis method, sintering conditions and powder particle size was investigated. It was found that for electrolytes of the same composition, those prepared via mechanochemical activation exhibited the highest total specific conductivity, which was improved with increasing Al- and decreasing Fe-content. The highest conductivity value at 700 degrees C. equal to 2.04 x 10(-2) s cm(-1), was observed for the La9.83Si5Al0.75Fe0.25O26 +/-delta electrolyte. La9.83Si4.5Fe1.5O26 +/-delta electrolyte samples synthesized using the Pechini method exhibited higher conductivity when sintered conventionally than when spark-plasma sintering (SPS) was used. (C) 2010 Elsevier B.V. All rights reserved.status: publishe