Magnetic field observations in high beta regions of the magnetosphere

OGO for magnetic field observations in high beta regions of magnetospher

Flight Without Horizon References in European Starlings

No abstract is available for this item

Flight without Horizon References in European Starlings

No abstract is available for this item

Leg Thrust Important in Flight Take-Off in the Pigeon

Measurements of the force generated by the legs of rock doves Columba livia during vertical and near-vertical take-off showed that the birds were able to develop an upward directed force of from 1.3 to 2.3 times their body weight. This force resulted in an instantaneous acceleration of 15.63 ms−2 at maximum thrust. Motion pictures taken during the take-off showed that as the birds\u27 feet left the experimental perch, their wings were in the overhead clap position. We suggest that the vertical take-off in birds is accomplished in three stages; leg thrust, clap-and-fling and steady-state flight

Bridging the gap between geometric and algebraic multi-grid methods

In this paper, a multi-grid solver for the discretisation of partial differential equations on complicated domains is developed. The algorithm requires as input the given discretisation only instead of a hierarchy of discretisations on coarser grids. Such auxiliary grids and discretisations are generated in a black-box fashion and are employed to define purely algebraic intergrid transfer operators. The geometric interpretation of the algorithm allows one to use the framework of geometric multigrid methods to prove its convergence. The focus of this paper is on the formulation of the algorithm and the demonstration of its efficiency by numerical experiments, while the analysis is carried out for some model problems