Search for dissertations about: "spectral density"

Showing result 1 - 5 of 195 swedish dissertations containing the words spectral density.

2. 1. Some Contributions to Filtering, Modeling and Forecasting of Heteroscedastic Time Series

   Author : Pär Stockhammar; Lars-Erik Öller; Daniel Thorburn; Agustin Maravall; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Heteroscedasticity; variance stabilizing filters; the mixed Normal - Asymmetric Laplace distribution; density forecasting; detrending filters; spectral analysis; the connection between financial data and economic growth; Statistics; Statistik; Statistics; statistik;

   Abstract : Heteroscedasticity (or time-dependent volatility) in economic and financial time series has been recognized for decades. Still, heteroscedasticity is surprisingly often neglected by practitioners and researchers. This may lead to inefficient procedures. READ MORE

4. 2. ROBUST DETECTION AND SPECTRAL ANALYSIS OF SIGNALS WITH APPLICATIONS IN SPECTROSCOPY

   Author : Naveed Butt; Matematisk statistik; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Detection; NQR; NMR; Raman Spectroscopy; Spectral Analysis.;

   Abstract : Modern spectroscopic techniques, such as nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR), and Raman spectroscopy, rely heavily on statistical signal processing systems for decision making and information extraction. The first part of this thesis introduces novel robust algorithms for detection, estimation, and classification of signals obtained through these spectroscopic techniques. READ MORE

5. 3. Multi-spectral analysis of fine scale aurora

   Author : Hanna Dahlgren; Göran Marklund; Nickolay Ivchenko; Fred Sigernes; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Plasma physics; Plasmafysik; Optics; Optik;

   Abstract : The Aurora Borealis is the visible manifestation of the complex plasma interaction between the solar wind and the Earth's magnetosphere and ionosphere. Ground based and in situ measurements demonstrate a prevalence of dynamic fine structure within auroral displays, with spatial scales down to tens of metres and time variations occurring on a fraction of a second. READ MORE

6. 4. Analysis and Design of Spatially-Coupled Codes with Application to Fiber-Optical Communications

   Author : Christian Häger; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bit mapper; generalized product codes; generalized low-density parity-check codes; bounded-distance decoding; density evolution; spatial coupling; staircase codes.; braided codes; Bit-interleaved coded modulation;

   Abstract : The theme of this thesis is the analysis and design of error-correcting codes that are suitable for high-speed fiber-optical communication systems. In particular, we consider two code classes. The codes in the first class are protograph-based low-density parity-check (LDPC) codes which are decoded using iterative soft-decision decoding. READ MORE

7. 5. Noise Applications in Light Water Reactors with Traveling Perturbations

   Author : Victor Dykin; Chalmers tekniska högskola; []
   Keywords : 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;

   Abstract : 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. READ MORE