Sökning: "Spectral lines"

Visar resultat 6 - 10 av 121 avhandlingar innehållade orden Spectral lines.

1. 6. Spectral lines as probes of surface gravities and galactic nucleosynthesis

   Författare :Bengt Edvardsson; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER

3. 7. ROBUST DETECTION AND SPECTRAL ANALYSIS OF SIGNALS WITH APPLICATIONS IN SPECTROSCOPY

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

   Sammanfattning : 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. LÄS MER

4. 8. On the Chemical Composition of Metal-Poor Stars : Impact of Stellar Granulation and Departures from Local Thermodynamic Equilibrium on the Formation of Spectral Lines

   Författare :Remo Collet; Bengt Gustafsson; Martin Asplund; Roger Cayrel; Uppsala universitet; []
   Nyckelord :Astronomy; late-type stars; stellar abundances; stellar atmospheres; spectral line formation; convection; hydrodynamics; Galactic chemical evolution; Astronomi;

   Sammanfattning : The information about the chemical compositions of stars is encoded in their spectra. Accurate determinations of these compositions are crucial for our understanding of stellar nucleosynthesis and Galactic chemical evolution. LÄS MER

5. 9. Group-Sparse Regression : With Applications in Spectral Analysis and Audio Signal Processing

   Författare :Ted Kronvall; Statistical Signal Processing Group; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sparse regression; group-sparsity; statistical modeling; regularization; hyperparameter-selection; spectral analysis; audio signal processing; classification; localization; multi-pitch estimation; chroma; convex optimization; ADMM; cyclic coordinate descent; proximal gradient;

   Sammanfattning : This doctorate thesis focuses on sparse regression, a statistical modeling tool for selecting valuable predictors in underdetermined linear models. By imposing different constraints on the structure of the variable vector in the regression problem, one obtains estimates which have sparse supports, i.e. LÄS MER

7. 10. Interstellar absorption across the electromagnetic spectrum

   Författare :Achim Tappe; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; interstellar medium ISM : general; supernova remnants Crab Nebula ; emission lines; — quasars: absorption lines;

   Sammanfattning : We report results of a multi-wavelength study of interstellar absorption in diffuse molecular clouds that lie in the direction of flat-spectrum quasars. Quasars as back-ground sources allow the measurement of Galactic interstellar absorption across the electromagnetic spectrum from mm to X-ray wavelengths. LÄS MER