Sökning: "spectral density functions"

Visar resultat 1 - 5 av 25 avhandlingar innehållade orden spectral density functions.

1. 1. Theory of water-proton spin relaxation in complex biological systems

   Författare :Zhiwei Chang; Biofysikalisk kemi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spin relaxation theory; immobilized macromolecules; magnetic relaxation dispersion; integral longitudinal relaxation rate; stochastic Liouville equations; multi-spin systems; cross-mode relaxation; spectral density functions;

   Sammanfattning : In complex biological systems (e.g. gels, cross-linked proteins and biological tissues), the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. LÄS MER

3. 2. Lineshape in Quantum Cascade Lasers - Temperature, Screening and Broadening

   Författare :Rikard Nelander; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum Cascade Lasers; quantum wells; spectral lineshape; Non-Equilibrium Green s Functions; screening; temperature dependence;

   Sammanfattning : This dissertation deals with the optical properties of Quantum Cascade Lasers (QCLs). Studies are performed using transport calculations employing the theory of Non-Equilibrium Green's Functions, and screening is studied within the Random Phase Approximation. Focus is put on the temperature dependent effects in THz QCLs. LÄS MER

4. 3. Noise Applications in Light Water Reactors with Traveling Perturbations

   Författare :Victor Dykin; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Green s function technique; transit times; decay ratio; cross-correlation function; void fraction; global and regional instabilities; propagating density perturbation; BWR stability; reduced order models; non-white driving force; local component; Monte Carlo; space-dependent neutron noise; density wave oscillations;

   Sammanfattning : Neutron noise induced by perturbations traveling with the coolant of light water reactors (LWRs) is investigated. Different methods to simulate the effect of propagating perturbations are considered. The studies are performed in both open- and closed-loop systems and summarized in three chapters. LÄS MER

5. 4. Effect of Uncertainty of Rock Properties on Radionuclide Transport by Groundwater : Implications for Performance Assessments of the Repository of Spent Nuclear Fuel in Heterogeneous Bedrock

   Författare :Shulan Xu; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Radionuclide migration; heterogeneous rock property; stochastic process spectral analysis; temporal moments; auto-covariance functions; sorption kinetics; performance assessment; Geovetenskap; Earth sciences; Geovetenskap; Sedimentology; sedimentologi;

   Sammanfattning : The overall objective of the current study is to develop a quantitative understanding of the effects of spatial variability in physical and geochemical properties of crystalline rock on the migration of radionuclides along a single fracture in bedrock. A stochastic model was developed to describe the transport of solutes in fractured rock. LÄS MER

7. 5. Towards Undistorted Fluorescence for Tissue Diagnostics and Therapy Monitoring

   Författare :Haiyan Xie; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; upconversion; upconverting nanoparticles; fluorescence-guided-surgery; fluorescence diagnostics; photodynamic therapy; multi-spectral imaging; spectroscopy; biomedical optics; fluorescence; Fysicumarkivet A:2014:Xie;

   Sammanfattning : Fluorescence techniques for applications in tissue diagnostics and therapy monitoring were investigated and developed in the work presented in this thesis. The aim was to develop fluorescence diagnostics for the detection of malignant tumors and better delimitation of the tumor margins, using the enhanced contrast in fluorescence between tumor and surrounding healthy tissue. LÄS MER