Doktorgradsavhandlinger (NT-fak): Recent submissions

Now showing items 221-240 of 305

    • Analysis and Interpretation of C-band Polarimetric SAR signatures of Sea Ice 

      Moen, Mari-Ann (Doctoral thesis; Doktorgradsavhandling, 2015-01-16)
      Operational sea ice charts are currently produced manually, an inefficient process resulting in subjective ice charts. Hence, there is a need for automating this procedure. This thesis investigates how polarimetric microwave radar signatures relate to the physical properties of sea ice, and how these signatures may contribute to the development of robust automatic algorithms. Our analyses are based ...

    • Characterization of Low Backscatter Regions in the Marine Environment by Multipolarization C- and X-band Synthetic Aperture Radar Data 

      Skrunes, Stine (Doctoral thesis; Doktorgradsavhandling, 2014-10-10)
      The focus of this thesis is the application of multipolarization SAR data for characterization of marine oil spills and other low backscatter ocean phenomena. A variety of SAR descriptors are investigated for the purpose of discriminating between oil spills and look-alikes. The effects of various parameters on the imaging, including sensor frequency, imaging geometry and oil properties, are addressed. ...

    • A multi-proxy approach for reconstructing oceanographic dynamics during the Holocene Development and Application of benthic foraminifera as proxies in the Polar North Atlantic 

      Skirbekk, Kari (Doctoral thesis; Doktorgradsavhandling, 2014-10-23)
      Two sediment cores and several sediment surface samples have been retrieved in order to develop and apply benthic foraminifera as proxies in the Polar North Atlantic. The purpose of the surface samples was to develop the Mg/Ca method for cold water environments, as this has been proven a valuable paleo-thermometer for several marine environments. This was done for three species of Benthic foraminifera: ...

    • Statistical methods for scale-invariant and multifractal stochastic processes. 

      Løvsletten, Ola (Doctoral thesis; Doktorgradsavhandling, 2014-10-03)
      This thesis focuses on stochastic modeling, and statistical methods, in finance and in climate science. Two financial markets, short-term interest rates and electricity prices, are analyzed. We find that the evidence of mean reversion in short-term interest rates is week, while the “log-returns” of electricity prices have significant anti-correlations. More importantly, empirical analyses confirm ...

    • Multi-Locality Based Local and Symbiotic Computing for Interactively fast On-Demand Weather Forecasting for Small Regions, Short Durations, and Very High-Resolutions 

      Fjukstad, Bård (Doctoral thesis; Doktorgradsavhandling, 2014-09-19)
      Modern weather forecasting is based on forecasts from huge numerical models executed on large supercomputer clusters in large computer centers. Production deadlines for forecast and available computational resources are the main factors for having to limit the forecast region size, spatial resolution, forecast duration and detail level of the weather model used. Modern numerical models currently ...

    • A Holocene palaeoceanographic multi-proxy study on the variability of Atlantic water inflow and sea ice distribution along the pathway of Atlantic water 

      Berben, Sarah (Doctoral thesis; Doktorgradsavhandling, 2014-10-14)
      The aim of this PhD thesis is to deliver improved quantitative reconstructions of sub-surface temperatures, salinities and seasonal sea ice distribution. Additionally, the natural variability of Atlantic water inflow and seasonal sea ice distribution and possible forcing mechanisms such as solar insolation, atmospheric circulation patterns (e.g. North Atlantic Oscillation (NAO)) and atmosphere-sea ...

    • Environmental response to past and recent climate variability in the Trondheimsfjord region, central Norway - A multiproxy geochemical approach 

      Faust, Johan Christoph (Doctoral thesis; Doktorgradsavhandling, 2014-07-04)
      Norwegian fjords have a great potential for providing high-resolution sedimentary records that reflect local terrestrial and marine processes and therefore, fjords offer unique opportunities for the investigation of sedimentological and geochemical climatically induced processes. However, the complexity of fjord systems in terms of bathymetry and oceanography requires a profound knowledge of the ...

    • Paleoceanography of the NE North Atlantic during the Holocene 

      Groot, Diane (Doctoral thesis; Doktorgradsavhandling, 2014-09-26)
      This thesis aimed at enhancing our understanding of the oceanographic variability of the Nordic Seas during the last 11,000 years. The Nordic Seas are a key area within the Atlantic Meridional Overturning Circulation (AMOC), a process which helps to maintain the present mild climate of northwestern Europe through its meridional heat transport and plays an important role in global heat distribution. ...

    • Complex Network Structure Patterns in Open Internet Communities for People with Diabetes 

      Chomutare, Taridzo Fred (Doctoral thesis; Doktorgradsavhandling, 2014-05-14)
      Type 2 diabetes is one of the greatest challenges that continues to grow because of the ageing population, increasing morbid obesity and sedentary lifestyles. Social media such as Facebook and YouTube have transformed the way people interact in general and on the Internet, but the role of social media in healthcare is still not well-understood. Current understanding of the association between ...

    • Sedimentary processes, late Cenozoic evolution and sediment yield on the continental margin offshore Troms, northern Norway 

      Rydningen, Tom Arne (Doctoral thesis; Doktorgradsavhandling, 2014-06-19)

    • Long Range Memory in Time Series of Earth Surface Temperature 

      Østvand, Lene (Doctoral thesis; Doktorgradsavhandling, 2014-05-23)
      Long-range memory (LRM) has been found in numerous natural data records, both in geophysics and other fields. In this thesis LRM in surface temperature time series is studied, and comparison with short-range memory (SRM) models performed. Trends are important in climate studies, but the trend definition is ambiguous. Two different approaches are included here: the trend described as a function ...

    • Associations of pulmonary parameters with accelerometer data 

      Dias, André (Doctoral thesis; Doktorgradsavhandling, 2014-03-25)
      In Europe it is estimated that the number of elderly people aged above 65 will have doubled by 2060. In several chronic pulmonary diseases patients can suffer recurrent exacerbation episodes that can lead to severe breathing or death. In this thesis we explore the association of physical activity to lung health parameters, focusing on cystic fibrosis and chronic obstructive pulmonary disease ...

    • Sub-seabed fluid-flow systems and gas hydrates of the SW Barents Sea and North Sea margins 

      Vadakkepuliyambatta, Sunil (Doctoral thesis; Doktorgradsavhandling, 2014-04-25)
      Denne avhandlingen omfatter studier av utbredelse og evolusjon av fluid migrasjonssystemer og gasshydrater i SV Barentshavet og nordlige Nordsjøen. Avhandlingen er basert på tolkning av seismiske og brønndata og numerisk modelling av hydratstabiliteten. Store fluid lekkasjestrukturer forekommer i SV Barentshavet og viser kobling mot de store tektoniske forkastningssytemene. Det er trolig istidene ...

    • Real-space all-electron Density Functional Theory with Multiwavelets 

      Jensen, Stig Rune (Doctoral thesis; Doktorgradsavhandling, 2014-03-20)
      This thesis presents the implementation of a numerical real-space method for the calculation of the electronic structure of molecular systems within the self-consistent field approximations of quantum chemistry. The code is based on the multi-resolution multiwavelet basis which provide sparse representations of functions and operators, in particular integral operators with Green's function convolution ...

    • The Omni-Kernel Architecture: Scheduler Control Over All Resource Consumption in Multi-Core Computing Systems 

      Kvalnes, Åge Andre (Doctoral thesis; Doktorgradsavhandling, 2014-03-13)
      Clouds commonly employ virtual machine technology to leverage and efficiently utilize computational resources in data centers. The workloads encapsulated by virtual machines contend for the resources of their hosting machines and interference from resource sharing can cause unpredictable performance. Despite the use of virtual machine technology, the role of the operating system as an arbiter of ...

    • Studying usage and experiences of mHealth technology for its improved usability - Mixed methods research for understanding users’ long-term engagement with the Few Touch application for self-management of Type 2 diabetes mellitus - 

      Tatara, Naoe (Doctoral thesis; Doktorgradsavhandling, 2014-02-28)
      In spite of a number of mHealth (use of mobile computing for health care) studies targeting people with diabetes, there has not yet been any clear evidence of its effect. Due to obscurity regarding subjects’ engagement with each component of the provided technology, it is not clear which factors are important and why. Considering that behavior change is a path of improvement in self-management of ...

    • Circulation and Exchanges at High-latitude Ocean Margins: Dynamical models and Observations from Instrumented Seals 

      Zhou, Qin (Doctoral thesis; Doktorgradsavhandling, 2014-01-14)
      Circulation and exchange processes at high-latitude ocean margins are investigated in this thesis, by using analytical models, numerical simulations and hydrographic data. In the Northern Hemisphere, the establishment of Atlantic Water transport as a topographically steered slope current has been investigated. A simplified analytical model based on geostrophic balance predicts that buoyancy loss ...

    • Time-frequency characterization of harmonizable random processes 

      Hindberg, Heidi (Doctoral thesis; Doktorgradsavhandling, 2009)
      In this thesis we study how to characterize nonstationary harmonizable random processes simultaneously in time and frequency. Unlike stationary random processes, harmonizable processes can have a frequency content that changes with time. Rather than working directly with the process itself, we analyze the second-order moment functions of the process and characterize the process from these moments. ...

    • Statistical Analysis of Medical Shapes and Directional Data 

      Schulz, Jörn (Doctoral thesis; Doktorgradsavhandling, 2013-12-18)
      The use of statistical shape analysis in medical settings has increased during the last decades. This thesis presents contributions to three major topics of statistical shape analysis with application to medical problems. These topics are: the modeling of the shape by a geometrical model, the study of rotational shape deformations and the comparison of shapes between populations. Paper I presents ...

    • Permian depositional and environmental development in Svalbard 

      Dustira, Anna Marie (Doctoral thesis; Doktorgradsavhandling, 2013-10-31)
      The main objective of this thesis is to improve the knowledge on the depositional and environmental development of Svalbard during the Permian (299–252 Ma), with a primary focus on the Early to Late Permian Kapp Starostin Formation (Tempelfjorden Group). Thirteen localities of Permian sedimentary strata were investigated with respect to their sedimentological and geochemical properties. Sediments ...