5,268 research outputs found
Black Holes and (0,4) SCFTs from Type IIB on K3
We study the central charges and levels of 2d
superconformal field theories that are dual to four- and five-dimensional BPS
black holes in compactifications of type IIB string theory on a K3 surface.
They arise from wrapping a D3-brane on a curve inside K3 and have
transverse space either an ALE or ALF space. These D3-branes have an AdS near horizon geometry where is a discrete
subgroup of . We compute the central charges and levels of the 2d SCFTs
both in the microscopic picture and from six-dimensional
supergravity. These quantities determine the black hole entropy via Cardy's
formula. We find agreement between the microscopic and macroscopic
computations. The contributions from one-loop quantum corrections to the
macroscopic result are crucial for this matching.Comment: 36 pages; v2: published version, footnotes added, minor typos
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Condition-based production and maintenance decisions
Machines used in production facilities deteriorate as a result of load and stress caused by production, and thus they eventually require maintenance to stay in an operating condition. The deterioration rate of a machine typically depends on the production rate, implying that we can control its deterioration, and thereby the maintenance planning, by dynamically adjusting the production rate.The main contribution of this thesis is to integrate the two research fields of production planning and condition-based maintenance. We introduce and explore the benefits of condition-based production and maintenance policies that exploit the relation between production and deterioration to improve the trade-off between the opposing targets of having high production outputs and low maintenance costs.The obtained insights are not only interesting from a theoretical point of view, but are also practically relevant due to the ongoing developments in the fields of sensor equipment and the internet of things. These developments enable operators to remotely monitor the deterioration of equipment and to control its usage in real-time, thereby allowing to implement automated condition-based production policies
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