Sökning: "Matematiskt problem"

Visar resultat 11 - 15 av 41 avhandlingar innehållade orden Matematiskt problem.

1. 11. Sparse Modeling Heuristics for Parameter Estimation - Applications in Statistical Signal Processing

   Författare :Stefan Ingi Adalbjörnsson; Matematisk statistik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; parameter estimation; sparse models; convex optimization; fundamental frequency; inharmonicity; audio localization; symbolic periodicity; alternating directions method of multipliers; N-dimensional decaying sinusoids.;

   Sammanfattning : This thesis examines sparse statistical modeling on a range of applications in audio modeling, audio localizations, DNA sequencing, and spectroscopy. In the examined cases, the resulting estimation problems are computationally cumbersome, both as one often suffers from a lack of model order knowledge for this form of problems, but also due to the high dimensionality of the parameter spaces, which typically also yield optimization problems with numerous local minima. LÄS MER

3. 12. Boundary singularities of plurisubharmonic functions

   Författare :Mårten Nilsson; Matematik LTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; pluripotential theory; envelope of plurisubharmonic functions; complex Monge-Ampère equation; Jensen measures;

   Sammanfattning : We study the Perron–Bremermann envelope P(μ, φ):=sup{u(z) ; u ∈ PSH(Ω), (ddcu)n≥ μ, u^* ≤ φ} on a B-regular domain Ω. Such envelopes occupy a central position within pluripotential theory as they, for suitable μ and φ harmonic and continuous on the closure of Ω, constitute unique solutions to the Dirichlet problem for the complex Monge–Ampère operator. LÄS MER

4. 13. Internal Cooling Design Using Multiphysics Topology Optimization

   Författare :Jonas Lundgren; Carl-Johan Thore; Anders Klarbring; Jan-Erik Lundgren; Joe Alexandersen; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Sammanfattning : This thesis investigates topology optimization (TO) as a tool for designing optimal internal cooling configurations in components subjected to external hot gas streams. The work is motivated by the challenge of simultaneously considering objectives from multiple physics domains, and the rapid development of additive manufacturing (AM) in the industry, which makes it possible to realize highly complex TO designs. LÄS MER

5. 14. On steady waves in two-layer fluids and ferrofluids

   Författare :Dag Nilsson; Partiella differentialekvationer; []
   Nyckelord :Internal waves; ferrofluids; partial differential equation; nonlinear waves; travelling waves; solitary waves; dynamical systems; Hamiltonian systems; non-local equations;

   Sammanfattning : This thesis concerns travelling waves in a two-layer fluid and on a ferrofluid jet. We prove existence of several types of such waves by reformulating the corresponding governing equation as an infinite dimensional dynamical system, where an unbounded spatial coordinate is used as time. LÄS MER

7. 15. Topics in the mean-field type approach to pedestrian crowd modeling and conventions

   Författare :Alexander Aurell; Boualem Djehiche; Xiaoming Hu; Roland Malhamé; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; pedestrian crowds; stochastic differential equations; mean field; stochastic control; games; backward dynamics; sticky boundary; stochastic maximum principle; social conventions; folkmassor; stokastiska differentialekvationer; medelfält; stokastisk styrning; limaktiga randvillkor; stokastiska maximumprincipen; dynamik med ändvillkor; spel; konventioner;

   Sammanfattning : This thesis consists of five appended papers, primarily addressingtopics in pedestrian crowd modeling and the formation of conventions.The first paper generalizes a pedestrian crowd model for competingsubcrowds to include nonlocal interactions and an arbitrary (butfinite) number of subcrowds. LÄS MER