Search for dissertations about: "nonlinear stability"

Showing result 21 - 25 of 172 swedish dissertations containing the words nonlinear stability.

2. 21. Geometric Methods for some Nonlinear Wave Equations

   Author : Jonatan Lenells; Matematik (naturvetenskapliga fakulteten); []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Natural science; Geodesic flow; Nonlinear wave equations; Geometric methods; Naturvetenskap;

   Abstract : A number of results related to the geometric interpretation of some dispersive nonlinear wave equations are presented. It is first described how some well-known shallow water equations arise geometrically as Euler equations for the geodesic flow on the Virasoro group endowed with certain right-invariant metrics. READ MORE

4. 22. Modeling and Control of VSC-HVDC Transmissions

   Author : Hector Latorre; Mehrdad Ghandhari; Luis Rouco; KTH; []
   Keywords : Control Lyapunov Functions; Energy Function; Modal Analysis; Transient Stability; Voltage Stability; VSC-HVDC Transmission.; TECHNOLOGY; TEKNIKVETENSKAP;

   Abstract : Presently power systems are being operated under high stress level conditions unforeseen at the moment they were designed. These operating conditions have negatively impacted reliability, controllability and security margins. FACTS devices and HVDC transmissions have emerged as solutions to help power systems to increase the stability margins. READ MORE

5. 23. Numerical studies of transtion in wall-bounded flows

   Author : Ori Levin; Dan Henningson; Nikolaus Adams; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layer; suction; wall jet; streaks; waves; periodic disturbance; localized disturbance; turbulent spot; algebraic growth; exponential growth; stability; transition thresholds; transition prediction; PSE; DNS; Fluid mechanics; Strömningsmekanik;

   Abstract : Disturbances introduced in wall-bounded flows can grow and lead to transition from laminar to turbulent flow. In order to reduce losses or enhance mixing in energy systems, a fundamental understanding of the flow stability and transition mechanism is important. READ MORE

6. 24. Weak Boundary and Interface Procedures for Wave and Flow Problems

   Author : Qaisar Abbas; Jan Nordström; Peter Eliasson; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; weak boundary conditions; multiple penalty; finite difference methods; summation-by-parts; high order scheme; hybrid methods; MUSCL scheme; shocks; stability; energy estimate; steady-state; non-reflecting; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

   Abstract : In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems. READ MORE

7. 25. Nonlinear Control of Unmanned Aerial Vehicles : Systems With an Attitude

   Author : Marcus Greiff; Institutionen för reglerteknik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nonlinear Control; Lyapunov Methods; Aerospace; Aerial Vehicles; Output Feedback; Control Theory;

   Abstract : This thesis deals with the general problem of controlling rigid-body systems through space, with a special focus on unmanned aerial vehicles (UAVs). Several promising UAV control algorithms have been developed over the past decades, enabling truly astounding feats of agility when combined with modern sensing technologies. READ MORE