Predicting flow reversals in a computational fluid dynamics simulated thermosyphon using data assimilation

A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth\u27s weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA) methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition for predicting the future state. Here, we build and verify four distinct DA methods, and then, we perform a twin model experiment with the computational fluid dynamics simulation of the loop using the Ensemble Transform Kalman Filter (ETKF) to assimilate observations and predict flow reversals. We show that using adaptively shaped localized covariance outperforms static localized covariance with the ETKF, and allows for the use of less observations in predicting flow reversals. We also show that a Dynamic Mode Decomposition (DMD) of the temperature and velocity fields recovers the low dimensional system underlying reversals, finding specific modes which together are predictive of reversal direction

A non-linear Reduced Order Methodology applicable to Boiling Water Reactor Stability Analysis

Das Stabilitätsverhalten von SWRen ist geprägt durch die thermohydraulische Kopplung zwischen Leistung, Massenstrom, Dichteverteilung und die neutronenphysikalische Rückkopplung. In dieser Arbeit wird erstmalig eine systematische, automatisierte und in sich geschlossene modellordnungsreduzierende Methodik entwickelt, welche allgemein auf verschiedenste dynamische Probleme und im Speziellen auf SWRen anwendbar ist. Dieses Vorgehen ermöglicht umfassende Analysen des nichtlinearen Verhaltens

Waves and turbulence on wavy coastal seabeds inducing vertical scalar transport

The project ”Waves and turbulence on wavy coastal seabeds inducing vertical scalar transport” is part of the graduate school Baltic Transcoast. This graduate school aimed to investigate the interaction between a coastal fen and the Baltic sea. In this work, the mixing and transport of the submarine groundwater discharge (SGD) was investigated in a defined laboratory experiment. For this, a new wave channel ground model was constructed and produced to facilitate the variation of different parameters for the investigations

Instruments for New Music: Sound, Technology, and Modernism

Player pianos, radio-electric circuits, gramophone records, and optical sound film—these were the cutting-edge acoustic technologies of the early twentieth century, and for many musicians and artists of the time, these devices were also the implements of a musical revolution. Instruments for New Music traces a diffuse network of cultural agents who shared the belief that a truly modern music could be attained only through a radical challenge to the technological foundations of the art. Centered in Germany during the 1920s and 1930s, the movement to create new instruments encompassed a broad spectrum of experiments, from the exploration of microtonal tunings and exotic tone colors to the ability to compose directly for automatic musical machines. This movement comprised composers, inventors, and visual artists, including Paul Hindemith, Ernst Toch, Jörg Mager, Friedrich Trautwein, László Moholy-Nagy, Walter Ruttmann, and Oskar Fischinger. Patteson’s fascinating study combines an artifact-oriented history of new music in the early twentieth century with an astute revisiting of still-relevant debates about the relationship between technology and the arts

Turkey, Migration and the EU: Potentials, Challenges and Opportunities

In the context of Turkey's accession to the EU, the issue of potential migration from Turkey and its impact upon European labor markets became one of the concerns of the EU, considering Turkey's growing population and young labor force. In 2011, half a century after the bi-lateral agreement between Turkey and Germany on labor recruitment in 1961, migration plays a key role in relations of Turkey with the EU and will even increase its significance - not necessarily for the next fifty years but certainly for the next decade. This book touches upon various aspects of the ongoing debate about the effects of Turkey's accession to the EU upon the migration flows and sheds light on various dimensions of current panorama, addresses policy implications as well as future challenges and opportunities