Sökning: "global modes"

Visar resultat 1 - 5 av 143 avhandlingar innehållade orden global modes.

1. 1. Analysis and control of transitional shear flows using global modes

   Författare :Shervin Bagheri; Dan Henningson; Alessandro Bottaro; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Fluid mechanics; flow control; hydrodynamic stability; global modes; jet in crossflow; flat-plate boundary layer; laminar-turbulent transition; Arnoldi method; Koopman modes; balanced truncation; direct numerical simulations.; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : In this thesis direct numerical simulations are used to investigate two phenomenain shear flows: laminar-turbulent transition over a flat plate and periodicvortex shedding induced by a jet in cross flow. The emphasis is on understanding and controlling the flow dynamics using tools from dynamical systems and control theory. LÄS MER

3. 2. Global stability and feedback control of boundary layer flows

   Författare :Espen Åkervik; Dan S. Henningson; Luca Brandt; Dwight Barkley; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Stability; Global Stability; Feedback Control; Control; Estimation; Absolute Convective Instabilities; Model Reduction; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : In this thesis the stability of generic boundary layer flows is studied from a global viewpoint using optimization methods. Global eigenmodes of the incompressible linearized Navier-Stokes equations are computed using the Krylov subspace Arnoldi method. LÄS MER

4. 3. Governing Climate Change under the Paris Regime : Meeting Urgency with Voluntarism

   Författare :Maria Jernnäs; Björn-Ola Linnér; Eva Lövbrand; Michele Betsill; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; global governance; governmentality; Paris Agreement; climate politics; Nationally Determined Contributions NDC ; nonstate actors; global styrning; governmentality; Parisavtalet; klimatpolitik; nationella klimat-planer NDC ; icke-statliga aktörer;

   Sammanfattning : The climate is changing. As the global mean temperature continues to rise, the immense urgency of addressing the climate change crisis is evident. LÄS MER

5. 4. Stability analysis and control design of spatially developing flows

   Författare :Shervin Bagheri; Dan Henningson; Martin Berggren; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Global modes; transient growth; model reduction; feedback control; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : Methods in hydrodynamic stability, systems and control theory are applied to spatially developing flows, where the flow is not required to vary slowly in the streamwise direction. A substantial part of the thesis presents a theoretical framework for the stability analysis, input-output behavior, model reduction and control design for fluid dynamical systems using examples on the linear complex Ginzburg-Landau equation. LÄS MER

7. 5. The materiality of media discourse : on capitalism and journalistic modes of writing

   Författare :Peter Berglez; Stig Arne Nohrstedt; Stig Hjarvard; Örebro universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; capitalism; journalistic modes of writing; media discourse; cultural materialist CDA; dialectics; dysfunctional homologies; ideologemes.; Media and communication studies; Medie- och kommunikationsvetenskap; SOCIAL SCIENCES; SAMHÄLLSVETENSKAP; Media and Communication Studies; Medie- och kommunikationsvetenskap;

   Sammanfattning : The purpose of the study is to analyse the relationship between the capitalist hegemonic order and the mass media, with the latter restricted to two elite newspapers (Swedish DN and Slovenian Delo) and the selection of news materials from three bodies of international media coverage: NATO’s military intervention in former Yugoslavia, 1999, the political demonstrations against the IMF and the World Bank in Prague, 2000, and 9/11, 2001. There are two sub-purposes, one theoretical-methodological and one political-democratic. LÄS MER