Fluid model for a network operating under a fair bandwidth-sharing policy

We consider a model of Internet congestion control that represents the randomly varying number of flows present in a network where bandwidth is shared fairly between document transfers. We study critical fluid models obtained as formal limits under law of large numbers scalings when the average load on at least one resource is equal to its capacity. We establish convergence to equilibria for fluid models and identify the invariant manifold. The form of the invariant manifold gives insight into the phenomenon of entrainment whereby congestion at some resources may prevent other resources from working at their full capacity

Narrow bandwidth video Patent

Improvements in receiver of narrow bandwidth television syste

Bandwidth in bolometric interferometry

Bolometric Interferometry is a technology currently under development that will be first dedicated to the detection of B-mode polarization fluctuations in the Cosmic Microwave Background. A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers in order to be competitive with imaging experiments. A crucial concern is that interferometers are presumed to be importantly affected by a spoiling effect known as bandwidth smearing. In this paper, we investigate how the bandwidth modifies the work principle of a bolometric interferometer and how it affects its sensitivity to the CMB angular power spectra. We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. Using an angular power spectrum estimator accounting for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation has been performed and confirms the analytical results. We conclude (i) that broadband bolometric interferometers allow broadband visibilities to be reconstructed whatever the kind of phase shifters used and (ii) that for dedicated B-mode bolometric interferometers, the sensitivity loss due to bandwidth smearing is quite acceptable, even for wideband instruments (a factor 2 loss for a typical 20% bandwidth experiment).Comment: 13 pages, 14 figures, submitted to A&