Sökning: "Phase jump"

Visar resultat 1 - 5 av 28 avhandlingar innehållade orden Phase jump.

  1. 1. Two Problems in non-linear PDE’s with Phase Transitions

    Författare :Karl Jonsson; Henrik Shahgholian; Tomas Sjödin; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Conductivity jump; Free boundary problem; Quasilinear elliptic equation; Mathematical techniques; Nonlinear analysis; Free boundary; Free-boundary problems; Quasi-linear elliptic; Quasilinear elliptic equations; Hele-Shaw flow; non-local; implicit function theorem; Heterogeneous Multi Scale; HMM; Finite Element; FEM; FE; Mathematics; Matematik;

    Sammanfattning : This thesis is in the field of non-linear partial differential equations (PDE), focusing on problems which show some type of phase-transition. A single phase Hele-Shaw flow models a Newtoninan fluid which is being injected in the space between two narrowly separated parallel planes. LÄS MER

  3. 2. Voltage Source Converters with Energy Storage Capability

    Författare :Hailian Xie; Hans-Peter Nee; Lennart Ängquist; Ambra Sannino; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Voltage source converter; StatCom; Energy storage; Active power compensation; Phase jump; Voltage dip; VSC; Weak network; Flux modulation; deadbeat control; Electric power engineering; Elkraftteknik;

    Sammanfattning : This project deals with voltage source converters with energy storage capability. The main objective is to study the possible benefits of energy storage to a power system with a VSC as the interface between them. First of all, a converter control system is proposed for a two level VSC. LÄS MER

  4. 3. On Power-system Benefits, Main-circuit Design, and Control of StatComs with Energy Storage

    Författare :Hailian Xie; Hans-Peter Nee; Lennart Ängquist; Timothy Green; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Energy storage; Voltage source converter; VSC; Static synchronous compensation; StatCom; Active power compensation; Phase jump; Voltage dip; Weak network; Flux modulation; Deadbeat current control; Transformer saturation; Dual thyristor converter; dc interface; Electrical engineering; Elektroteknik; Electric power engineering; Elkraftteknik;

    Sammanfattning : Static synchronous compensation (StatCom) is an application that utilizes a voltage source converter (VSC) to provide instantaneous reactive power support to the connected power system. Conventionally, StatComs are employed for reactive power support only. LÄS MER

  5. 4. Efficiency Enhancement Techniques for Free-Electron Lasers

    Författare :Alan Mak; Lunds universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; free-electron laser; accelerator physics; efficiency enhancement; undulator tapering; phase jump method; synchrotron radiation; Fysicumarkivet:2017:Mak;

    Sammanfattning : The central question addressed in this thesis is how to make the free-electron laser (FEL) more efficient. In recent years, coherent diffraction imaging provides an important motivation for efficiency enhancement. This is because a more efficient FEL process enables converting a larger fraction of the electron beam's power into optical power. LÄS MER

  7. 5. Pricing Portfolio Credit Derivatives

    Författare :Alexander Herbertsson; Göteborgs universitet; []
    Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Portfolio credit risk; intensity-based models; dynamic dependence modelling; default contagion; CDS; synthetic CDO tranches; index CDS; k-th-to-default swaps; CDS-correlation; default-correlation; Markov jump processes; multivariate phase-type distributions; matrix-analytic methods;

    Sammanfattning : This thesis consists of four papers on dynamic dependence modelling in portfolio credit risk. The emphasis is on valuation of portfolio credit derivatives. The underlying model in all papers is the same, but is split in two different sub-models, one for inhomogeneous portfolios, and one for homogeneous ones. LÄS MER