Aerodynamics of 3-dimensional bodies in transitional flow

Based on considerations of fluid dynamic simulation appropriate to hypersonic, viscous flow over blunt-nosed lifting bodies, a method was presented earlier for estimating drag coefficients in the transitional-flow regime. The extension of the same method to prediction of lift coefficients is presented. Correlation of available experimental data by a simulation parameter appropriate for this purpose is the basis for the procedure described. The ease of application of the method makes it useful for preliminary studies which involve a wide variety of three-dimensional vehicle configurations or a range of angles of attack of a given vehicle

Max-Weight Revisited: Sequences of Non-Convex Optimisations Solving Convex Optimisations

We investigate the connections between max-weight approaches and dual subgradient methods for convex optimisation. We find that strong connections exist and we establish a clean, unifying theoretical framework that includes both max-weight and dual subgradient approaches as special cases. Our analysis uses only elementary methods, and is not asymptotic in nature. It also allows us to establish an explicit and direct connection between discrete queue occupancies and Lagrange multipliers.Comment: convex optimisation, max-weight scheduling, backpressure, subgradient method

Proportional Fair MU-MIMO in 802.11 WLANs

We consider the proportional fair rate allocation in an 802.11 WLAN that supports multi-user MIMO (MU-MIMO) transmission by one or more stations. We characterise, for the first time, the proportional fair allocation of MU-MIMO spatial streams and station transmission opportunities. While a number of features carry over from the case without MU-MIMO, in general neither flows nor stations need to be allocated equal airtime when MU-MIMO is available