The Hydraulics of Roman Aqueducts: What do we know? Why should we learn ?

The Roman engineers were at the forefront of science and their engineering heritage included some magnificent aqueducts, many of which are still standing. While some scholars suggested that Roman engineers did not know the basic principle of conservation of mass, the Roman aqueducts provide a clear demonstration of the high level of hydraulic engineering expertise. The successful design and operation of these outstanding systems were massive achievements by modern standards. The development of regulation basins, culverts and energy dissipators was far from obvious. It is the writer's opinion that the leading Roman hydraulic engineers involved with the major aqueducts in Gaul and North-Africa understood the concepts of continuity and momentum

Impact des déversements d'orage sur la qualité de la Seine à l'étiage

Depuis plusieurs années, un important programme d'études est entrepris dont l'objectif est de décrire et de chiffrer les principales actions d'assainissement et d'épuration à mener pour satisfaire les critères de qualité nécessaires aux usages de l'eau des grandes rivières de l'agglomération parisienne. La présente communication est une contribution importante à la mise au point d'un modèle de qualité de la Seine devant permettre de définir les ordres de grandeur - et il convient d'insister sur ce terme des rejets tolérables en Seine par temps de pluie, lors du débordement des égoûts unitaires notamment, compatibles avec le respect des critères de qualité souhaités

A CDMA2000 Zero IF Receiver with Low-Leakage Integrated Front-End

This paper describes a highly integrated CDMA 2000 US-CEL band (880-MHz) receiver. The single-chip zero-IF design incorporates all receiver signal-path functions including the low-noise amplifier (LNA) on a single die. The complete receiver design exceeds the stringent linearity and local oscillator (LO) leakage requirements for this standard arising from the coexistence with narrow-band FM signals. The integrated LNA achieves 1.0-dB noise figure with +9-dBm IIP3 at high gain, and by maintaining LO leakage to the antenna port well below 80~dBm at all gain settings, no external LNA is required. The receiver is fabricated in a 0.25-µm 40-GHz ft BICMOS technology, and occupies 3mm2