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    • Risk assessment of wind farm development in ice proven area 

      Mustafa, Albara; Barabadi, Abbas; Markeset, Tore (Journal article; Tidsskriftartikkel; Peer reviewed, 2019)
      There many risks associated with wind farms operating in cold harsh areas, a number of these risks is caused by icing. Atmospheric and super-structure icing can cause ice accretion on wind turbines’ structure, and lead to public safety risks caused by ice throw and the failure of wind turbine’s components. Other risks can affect wind farm’s maintenance crew and their activities. Such risks are ...
    • Iron cycling in Arctic methane seeps 

      Hong, Wei-Li; Latour, Pauline; Sauer, Simone; Sen, Arunima; Gilhooly, William P.; Lepland, Aivo; Fouskas, Fotios (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-26)
      Anoxic marine sediments contribute a significant amount of dissolved iron (Fe<sup>2+</sup>) to the ocean which is crucial for the global carbon cycle. Here, we investigate iron cycling in four Arctic cold seeps where sediments are anoxic and sulfidic due to the high rates of methane-fueled sulfate reduction. We estimated Fe<sup>2+</sup> diffusive fluxes towards the oxic sediment layer to be in the ...
    • Predicting Transaction Latency with Deep Learning in Proof-of-Work Blockchains 

      Tedeschi, Enrico; Nordmo, Tor-Arne Schmidt; Johansen, Dag; Johansen, Håvard D. (Peer reviewed; Chapter, 2019)
      Proof-of-work based cryptocurrencies, like Bitcoin, have a fee market where transactions are included in the blockchain according to a first-price auction for block space. Many attempts have been made to adjust and predict the fee volatility, but even well-formed transactions sometimes experience delays and evictions unless an enormous fee is paid. % In this paper, we present a novel ...
    • Cyberspace Effects on Civil Society. The Ultimate Game-Changer or Not? 

      Montalvan Castilla, Johana Evelyn; Pursiainen, Christer Henrik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-04)
      The article studies the effects of the emergence of cyberspace, or digitization, on civil society, and develops an analytical framework to that effect. It is distinguished between four types of civil societies: apolitical, political, transnational, and uncivic. Each type of civil society is considered separately vis-à-vis cyberspace developments in order to understand what kind of civil society is ...
    • Deep Learning towards Autonomous Ship Navigation and Possible COLREGs Failures 

      Perera, Lokukaluge Prasad (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-17)
      A structured technology framework to address navigation considerations, including collision avoidance, of autonomous ships is the focus of this study. That consists of adequate maritime technologies to achieve the required level of navigation integrity in ocean autonomy. Since decision-making facilities in future autonomous vessels can play an important role under ocean autonomy, these technologies ...
    • Poincaré function for moduli of differential-geometric structures 

      Kruglikov, Boris (Journal article; Tidsskriftartikkel, 2019)
      The Poincaré function is a compact form of counting moduli in local geometric problems. We discuss its property in relation to V. Arnold’s conjecture, and derive this conjecture in the case when the pseudogroup acts algebraically and transitively on the base. Then we survey the known counting results for differential invariants and derive new formulae for several other classification problems in ...
    • A waveguide imaging platform for live-cell TIRF imaging of neurons over large fields of view 

      Opstad, Ida Sundvor; Ströhl, Florian; Fantham, Marcus J.; Hockings, Colin; Vanderpoorten, Oliver; Tartwijk, Francesca W. van; Qiaojin Lin, Julie; Tinguely, Jean-Claude; Dullo, Firehun Tsige; Kaminski‐Schierle, Gabriele S.; Ahluwalia, Balpreet Singh; Kaminski, Clemens F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-17)
      Large fields of view (FOVs) in total internal reflection fluorescence microscopy (TIRFM) via waveguides have been shown to be highly beneficial for single molecule localisation microscopy on fixed cells [1,2] and have also been demonstrated for short‐term live‐imaging of robust cell types [3‐5], but not yet for delicate primary neurons nor over extended periods of time. Here, we present a waveguide‐based ...
    • Integrable Systems in Four Dimensions Associated with Six-Folds in Gr(4, 6) 

      Doubrov, Boris; Ferapontov, Evgeny V; Kruglikov, Boris; Novikov, Vladimir S (Journal article; Tidsskriftartikkel, 2018-01-29)
      Let Gr(d, n) be the Grassmannian of <i>d</i>-dimensional linear subspaces of an <i>n</i>-dimensional vector space <i>V</i>. A submanifold <i>X</i> ⊂ Gr(<i>d, n</i>) gives rise to a differential system Σ(X) that governs <i>d</i>-dimensional submanifolds of <i>V</i> whose Gaussian image is contained in <i>X</i>. We investigate a special case of this construction where <i>X</i> is a six-fold in Gr(4, ...
    • Dispersionless integrable hierarchies and GL(2,R) geometry 

      Ferapontov, Evgeny V; Kruglikov, Boris (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-08)
      Paraconformal or GL(2, ℝ) geometry on an <i>n</i>-dimensional manifold <i>M</i> is defined by a field of rational normal curves of degree <i>n</i> – 1 in the projectivised cotangent bundle <i>ℙT*M</i>. Such geometry is known to arise on solution spaces of ODEs with vanishing Wünschmann (Doubrov–Wilczynski) invariants. In this paper we discuss yet another natural source of <i>GL</i>(2, ℝ) structures, ...
    • Differential invariants of Kundt waves 

      Kruglikov, Boris; McNutt, David Duncan; Schneider, Eivind (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-17)
      Kundt waves belong to the class of spacetimes which are not distinguished by their scalar curvature invariants. We address the equivalence problem for the metrics in this class via scalar differential invariants with respect to the equivalence pseudo-group of the problem. We compute and finitely represent the algebra of those on the generic stratum and also specify the behavior for vacuum Kundt ...
    • Beyond the grid: The promise of solar concentration for non-electrical energy generation 

      Apostoleris, Harry; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-09)
      As electricity from both photovoltaics and concentrating solar power has become dramatically more affordable in the last several years, the prospect of converting entire national electrical grids to run almost entirely on renewable energy has become feasible in any location with a strong solar resource. However, focusing only on the electric grid neglects the large portion of our energy usage which ...
    • Position prediction of marine seismic streamer cables using various kalman filter methods 

      Grindheim, Jan Vidar; Revhaug, Inge; Pedersen, Egil; Solheim, Peder (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-26)
      Towed seismic streamer cables are extensively employed for offshore marine petroleum exploration. With the increasing need for accurate streamer steering due to rising number and length of streamers and decreasing intrastreamer separation, as well as new types of survey configurations, accurate modeling, positioning, and path prediction of the streamers are imperative. In the present study, a variety ...
    • Cost-Effective Potential for Accurate Polarizable Embedding Calculations in Protein Environments 

      Reinholdt, Peter; Kjellgren, Erik Rosendahl; Steinmann, Casper; Olsen, Jógvan Magnus Haugaard (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-19)
      The fragment-based polarizable embedding (PE) model combined with an appropriate electronic structure method constitutes a highly efficient and accurate multiscale approach for computing spectroscopic properties of a central moiety including effects from its molecular environment through an embedding potential. There is, however, a comparatively high computational overhead associated with the ...
    • Label-free nanoscopy enabled by coherent imaging with photonic waveguides 

      Ströhl, Florian; Opstad, Ida Sundvor; Tinguely, Jean-Claude; Dullo, Firehun Tsige; Kaminski, Clemens F.; Ahluwalia, Balpreet Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-29)
      In this project it was found that Fourier ptychographic microscopy can be improved far beyond its conventional limits via waveguide-based optical systems. Extensive in silico studies showed that images obtained on highrefractive index material waveguide chips in conjunction with hyperspectral illumination light and finely designed waveguide geometries can be combined via a modified phase-retrieval ...
    • Temperature-driven variation in the removal of heavy metals from contaminated tailings leaching in northern Norway 

      Fu, Shuai; Lu, Jinmei (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-31)
      High amounts of tailings with a low recycling rate are generated during mining and smelting processes, and a lot of environmental problems were caused by heavy metal leaching from tailings. Temperature is a key point in heavy metals leaching, and knowing the effects of temperature on tailings leaching is useful for tailings management. A small-scale batch leaching experiment was conducted at different ...
    • Ship Performance and Navigation Information under High Dimensional Digital Models 

      Perera, Lokukaluge Prasad; Mo, Brage (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-04)
      Future vessels will be facilitated by modern internet of things to collect various ship performance and navigation information. Such information is collected as large-scale data sets, the so-called Big Data, that should be utilized towards digitalization of the shipping industry. However, various data handling challenges are encountered by the shipping industry during the phase of digitalization, ...
    • Strong Duschinsky Mixing Induced Breakdown of Kasha's Rule in an Organic Phosphor 

      Paul, Lopa; Moitra, Torsha; Ruud, Kenneth; Chakrabarti, Swapan (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-08)
      We present the novel observation that Duschinsky mixings can lead to the breakdown of Kasha’s rule in a white light phosphor molecule, dibenzo[<i>b,d</i>]thiophen-2-yl (4-chlorophenyl)methanone. Our theoretical analyses show the energy gap between the T<sub>1</sub> and T<sub>2</sub> states (0.48 eV) is too large to allow for any significant population of the T<sub>2</sub> state at room temperature ...
    • Electron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalysts 

      Bora, Pankaj L; Novotny, Jan; Ruud, Kenneth; Komorovsky, Stanislav; Marek, Radek (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-28)
      Electron and nuclear magnetic resonance spectroscopies are indispensable and powerful methods for investigating the molecular and electronic structures of open-shell systems. We demonstrate that the NMR and EPR parameters are extremely sensitive quantitative probes for the electronic spin density around heavy-metal atoms and the metal–ligand bonding. Using relativistic density-functional theory, we ...
    • Photo-transformation trajectories of Nitro-Spiropyran in Hybrid Compounds with [60]Fullerene 

      Pomogaev, Valdimir A; Avramov, Pavel V; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-12)
      Photo- and thermo- isomerization trajectories of various conversion pathways between nitro-spiropyran and its <i>trans–trans–cis</i> merocyanine form were produced and the role of nπ* states was investigated along the corresponding potential energy surface calculated using the ωB97XD functional and the cc-pVDZ basis set. The nondissociative nπ* states on the photoisomerization trajectories can switch ...
    • Effect on the longitudinal coherence properties of a pseudothermal light source as a function of source size and temporal coherence 

      Ahmad, Azeem; Mahanty, Tanmoy; Dubey, Vishesh; Butola, Ankit; Ahluwalia, Balpreet Singh; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-01)
      In the present Letter, a synthesized pseudothermal light source having high temporal coherence (TC) and low spatial coherence (SC) properties is used. The longitudinal coherence (LC) properties of the spatially extended monochromatic light source are systematically studied. The pseudothermal light source is generated from two different monochromatic laser sources: He–Ne (at 632 nm) and DPSS (at 532 ...