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Showing result 1 - 5 of 50 essays matching the above criteria.

1. 1. The solar abundance of beryllium : constraining the solar problem via non-LTE modelling

   University essay from

   Author : Daria Ogneva; [2023]
   Keywords : atomic processes; radiative transfer; abundance;

   Abstract : Accurately determining the solar abundance of beryllium is a key to calibrate transport processes at the base of convective zone, which in turn is an improvement upon existing solar models and general understanding of the physical processes within the Sun. To determine an abundance, assumptions about the solar atmosphere must be made. READ MORE

3. 2. GIS and remote sensing based mapping of microtopography and vegetation composition in a boreal mire complex

   University essay from SLU/Dept. of Forest Ecology and Management

   Author : Nils Helge Havertz; [2023]
   Keywords : Microtopography modelling; Remote sensing; Boreal mixed mires; Object Based Image Analysis OBIA ; random forest RF ;

   Abstract : Small scale variations in mire surface elevation referred to as microtopography are fundamental characteristics of mire ecosystems especially in the boreal region. Microtopography commonly classified into hummocks and hollows play a major role in several ecological, hydrological and biogeochemical processes including vegetation composition and carbon and methane dynamics. READ MORE

4. 3. Using forest reflectance modelling to estimate albedo for narrow-view satellites

   University essay from Lunds universitet/Institutionen för naturgeografi och ekosystemvetenskap; Lunds universitet/Fysiska institutionen

   Author : Nick Bergmans; [2023]
   Keywords : satellite; remote sensing; albedo; surface reflectance; vegetation; forest; machine learning; albedo estimation; Earth and Environmental Sciences;

   Abstract : Surface albedo estimations from remote sensing are invaluable for energy balance descrip- tions in climate research. The aim of this work is to evaluate the possibility of using Sentinel-2 satellite data to get the total albedo of a small, vegetated area. READ MORE

5. 4. Towards Automatic Model Atoms from the VALD Atomic Database: from He to U

   University essay from Uppsala universitet/Teoretisk astrofysik

   Author : Samuel Hermansson; [2023]
   Keywords : r-process; nucleosynthesis; kilonovae; VALD;

   Abstract : The ejecta following the collision and merging of two neutron stars (kilonova) are currently considered promising sites for nucleosynthesis of r-process elements. Since the observed kilonova in 2017, GW2017817, astrophysicists have been working to analyze the collected electromagnetic spectra, trying to identify r-process elements. READ MORE

6. 5. Atomic Structure Calculations Using Configuration-Interaction And Many-Body Perturbation Theory For Spectral Modelling Of Neutron Star Mergers : Example Of Ce I - Iv

   University essay from Uppsala universitet/Teoretisk fysik

   Author : Fredrik Plane; [2023]
   Keywords : Computational atomic physics; Atomic physics; Physics; Astronomy; Astrophysics; Neutron stars; Stars; Relativisitc atomic physics; Configuration-interaction; Perturbation theory; Many-body perturbation theory;

   Abstract : The binary neutron star merger of 2017 and its corresponding electromagnetic signature resembling that of a kilonova has been one of the most groundbreaking astrophysical occurrences in the last decade. Indications of r-process nucleosynthesis in this event presents new opportunities for learning about the astrophysical origin of heavy elements. READ MORE