The Doctrine of Thrasymachus in Plato's Republic

"It is the purpose of this article to attempt to re-examine the account of Thrasymachus' doctrine in Plato's Republic, and to show how it can form a self-consistent whole. [...] In this paper it is maintained that Thrasymachus is holding a form of [natural right]." Note: Volume 40 = new series

Active acoustic cloaking of cylindrical shells in low Mach number flow

The vibro-acoustic responses of a two-dimensional cylindrical shell in low Mach number flow are herein derived. The analytical model takes into account the structural elasticity and coupling of the shell vibration with its interior and exterior acoustic fields in the presence of a moving fluid. The cylindrical shell is modelled using Donnell-Mushtari theory. Taylor transformations are employed to transfer the convected wave equation into the ordinary wave equation which was then solved using scattering theory. Three excitation cases corresponding to a plane wave, an external monopole source and a radial point force applied directly to the shell are considered. Shell circumferential resonances and interior acoustic resonances are identified. Two active control strategies are then applied to acoustically cloak the cylindrical shell at its acoustic and structural resonances. The first control approach employs acoustic control sources in the exterior fluid domain. In the second approach, control forces are applied to directly excite the elastic shell, whereby the structural response is actively modified to manipulate the scattered and radiated acoustic fields arising from plane wave excitation of the shell. Results show that the second approach is superior in terms of both reduced control effort and cloaking of the global exterior domain. For both control approaches, the performance of the active cloak is shown to deteriorate if the convected flow field is not accounted for in the control process

A szofiasta mozgalom

Adaptált digitalizált tartalom. A Speciális Hallgatói Ügyeket Támogató Iroda a fogyatékossággal élő hallgatók megsegítése céljából tankönyveket adaptál. A tananyag akadálymentes, adaptált változata az arra jogosult (a fogyatékosügyi koordinátoroknál regisztrált) hallgatók számára érhető el