Whereas the computing power of DSP or general-purpose processors was sufficient for 3G baseband telecommunication algorithms, stringent timing constraints of 4G wireless telecommunication systems require computing-intensive data-driven architectures. Managing the complexity of these systems within the energy constraints of a mobile terminal is becoming a major challenge for designers. System-level low-power policies have been widely explored for generic software-based systems, but data-flow architectures used for high data-rate telecommunication systems feature heterogeneous components that require specific configurations for power management. In this study, we propose an innovative power optimization scheme tailored to self-synchronized data-flow systems. Our technique, based on the synchronous data-flow modeling approach, takes advantage of the latest low-power techniques available for digital architectures. We illustrate our optimization method on a complete 4G telecommunication baseband modem and show the energy savings expected by this technique considering present and future silicon technologies
Shock waves in argon and in air have been observed when focusing a 0.8 J, 40 nsec, Q-switched ruby laser beam onto a beryllium target in the presence of gas at various pressures ranging fron 2×10−1 to 3 Torr. High-speed streak and framing camera as well as a prism spectrograph have been used as diagnostic tools. Space-resolved spectra show, besides an intense continuum, Stark-broadened lines from Be I and Be II. The reinforced argon lines when moving off the Be target surface are probably due to a shock wave driven by the Be plasma acting as a piston. A simple theoretical model taking this mechanism into account is proposed. Calculated curves for the outer radius variations of the shock front fit closely the experimental results.
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