Viser treff 566-585 av 915

    • Observations of sunlit N2+ aurora at high altitudes during the RENU2 flight 

      Ellingsen, Pål Gunnar; Lorentzen, Dag Arne; Kenward, David; Hecht, James H.; Evans, J. Scott; Sigernes, Fred; Lessard, Marc (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-24)
      We present measurements of sunlit aurora during the launch of the Rocket Experiment for Neutral Upwelling 2 (RENU2) on the 13 December 2015, 07:34 UTC. The in situ auroral conditions coincide with those of sunlit aurora and were characterised by the 391.4 and 427.8 nm N<sub>2</sub> <sup>+</sup> emissions. A correlation between several auroral wavelengths, as measured by a meridian-scanning ...
    • Offshore Drone Logistics Optimization and Corporate Feasibility 

      Rasheed, Muhammad Talha (Master thesis; Mastergradsoppgave, 2022-05-16)
      Drones can help offshore logistics to improve safety, increase production efficiency, and reduce CO2 emissions. Drones will also be used in the development of new energy solutions on offshore stations. The aim is to see new logistics and support infrastructure, which will complement what we now have on ships and helicopters. Johan Castberg FPSO requires offshore drone logistics operations and for ...
    • On a New Class of Hardy-type Inequalities 

      Adeleke, EO; Cizmesija, Aleksandra; Oguntuase, JA; Persson, Lars Erik; Pokaz, D (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-11-05)
      In this paper, we generalize a Hardy-type inequality to the class of arbitrary non-negative functions bounded from below and above with a convex function multiplied with positive real constants. This enables us to obtain new generalizations of the classical integral Hardy, Hardy-Hilbert, Hardy-Littlewood-Pólya, and Pólya-Knopp inequalities as well as of Godunova’s and of some recently obtained ...
    • On Context, Issues, and Pitfalls of Expert Judgement Process in Risk Assessment of Arctic Offshore Installations and Operations 

      Naseri, Masoud; Barabadi, Abbas (Journal article; Tidsskriftartikkel; Peer reviewed, 2018)
      Decisions to be made in the Arctic offshore operations rely extensively on risk assessment outputs, which require a great deal of historical data and information. However, at the current stage of operating in the Arctic offshore – compared to normal-climate regions – such data is scarce due to the limited industrial activities to date. Lack of data on the probability of the occurrence of an unwanted ...
    • On crystallographic aspects of heterogeneous plastic flow during ductile tearing: 3D measurements and crystal plasticity simulations for AA7075-T651 

      Morgeneyer, Thilo; Khadyko, Mikhail; Buljac, A; Helfen, Lukas; Hild, Francois; Benallal, Ahmed; Børvik, Tore; Hopperstad, Odd Sture (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-21)
      Crystallographic aspects of heterogeneous plastic flow during ductile tearing are assessed experimentally by combining in situ synchrotron laminography imaging of notched flat samples with a full-field measurement technique and numerical simulations with the crystal plasticity finite element method (CP-FEM). Advantage is taken of the plane strain condition in the region ahead of the notch root (i.e., ...
    • On geometric construction of some power means 

      Høibakk, Ralph; Lukkassen, Dag; Persson, Lars Erik; Meidell, Annette (Journal article; Peer reviewed, 2018-11-27)
      In the homogenization theory, there are many examples where the effective conductivities of composite structures are power means of the local conductivities. The main aim of this paper is to initiate research concerning geometric construction of some power means of three or more variables. We contribute by giving methods for the geometric construction of the harmonic mean $ P_{-1} $ and the arithmetic ...
    • On heat conduction in domains containing noncoaxial cylinders 

      Lukkassen, Dag; Meidell, Annette (Journal article; Peer reviewed; Tidsskriftartikkel, 2012)
      We consider heat conduction in domains containing noncoaxial cylinders. In particular, we present some regularity results for the solution and consider criteria which ensure the single valueness of the corresponding complex potential. Examples are discussed. In addition, we present some classes of cases where the parameters describing the solution are rational. Alternative ways of calculating the ...
    • On operator estimates in homogenization of nonlocal operators of convolution type 

      Piatnitski, Andrei; Sloushch, Vladimir; Suslina, Tatiana; Zhizhina, Elena (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-11)
    • On Some Power Means and Their Geometric Constructions 

      Høibakk, Ralph; Lukkassen, Dag; Meidell, Annette; Persson, Lars Erik (Journal article; Peer reviewed; Tidsskriftartikkel, 2018)
      The main aim of this paper is to further develop the recently initiatedresearch concerning geometric construction of some power means wherethe variables are appearing as line segments. It will be demonstratedthat the arithmetic mean, the harmonic mean and the quadratic meancan be constructed for any number of variables and that all power meanswhere the number of variables are n = 2m, m 1 2 N for all ...
    • On the boundedness of subsequences of Vilenkin-Fejér means on the martingale Hardy spaces 

      Persson, Lars Erik; Tephnadze, George; Tutberidze, Giorgi (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03)
      In this paper we characterize subsequences of Fejér means with respect to Vilenkin systems, which are bounded from the Hardy space <i>H<sub>p</sub></i> to the Lebesgue space <i>L<sub>p</sub></i>, for all 0 < p < 1/2. The result is in a sense sharp.
    • On the Heat and Wave Equations with the Sturm-Liouville Operator in Quantum Calculus 

      Shaimardan, Serikbol; Persson, Lars-Erik; Tokmagambetov, Nariman (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-19)
      In this paper, we explore a generalised solution of the Cauchy problems for the q-heat and q-wave equations which are generated by Jackson’s and the q-Sturm-Liouville operators with respect to t and x, respectively. For this, we use a new method, where a crucial tool is used to represent functions in the Fourier series expansions in a Hilbert space on quantum calculus. We show that these solutions ...
    • On Weighted Fourier InequalitieS –– Some New Scales of Equivalent Conditions 

      Kufner, Alois; Persson, Lars-Erik; Samko, Natasha G. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06)
      For Lebesgue spaces on R<sup>n</sup>, we study two-weight p → q-inequalities for Fourier transform. Some sufficient conditions on weights for such inequalities are known for special ranges of parameters p and q. In the same ranges of parameters we show, that in every case each of those conditions can be replaced by infinitely many conditions, even by continuous scales of conditions. We also ...
    • Onshore and Offshore Coordination of Logistics Services at Seaports 

      Adu-Gyamfi Appiah, Bright (Master thesis; Mastergradsoppgave, 2019-06-28)
      As global trade increases, sizes of vessels and cargo throughputs have also experienced a sudden rise thereby putting excess pressure on ship berths and ports. This is shifting most ports to much smarter technological solutions with the aim of optimizing operations, increasing efficiency and reducing logistics cost without the need for huge infrastructural and equipment investments. Developing the ...
    • Optical water types of the Nordic Seas and adjacent areas 

      Aas, Eyvind; Højerslev, Niels Kristian; Høkedal, Jo; Sørensen, Kai (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-20)
      A new map of Jerlov's optical water types in the Nordic Seas and adjacent waters at 139 locations, as well as a table with statistical and geographical properties of the vertical attenuation coefficient of downward irradiance at 475 nm, are presented. The data analysis is based on 715 recordings at different stations, at latitudes between 54° and 82°N, and longitudes between 31°W and 49°E, obtained ...
    • Optimal bruk av reaktive ressurser 

      Arnesen, Jan Tore (Master thesis; Mastergradsoppgave, 2021-05-18)
      God kontroll av reaktiv effekt er en helt nødvendig del av et velfungerende kraftsystem. Reaktiv effekt er funksjon av spenning og lastvinkel, men er i størst grad påvirket av spenningen under normale forhold. Det finnes mange forskjellige reaktive ressurser i kraftsystemet, og de har forskjellige egenskaper og karakteristikker. Statiske reaktive ressurser er kondensatorbatterier, reaktorer og ...
    • Optimal placement of PMUs considering logical topology of communication medium power system observability 

      Nikumbh, Bhushan Madan (Master thesis; Mastergradsoppgave, 2016-11-07)
      A phasor measurement unit (PMU) has a unique ability of providing synchronized phasor measurements of voltage and currents. This ability distinguishes it from all other metering devices. It has been perceived that PMUs hold the capability of revolutionizing the way of power system monitoring and control. However, high per unit cost and challenges related to its communication system has made ...
    • Optimal power flow based coordinated reactive and active power control to mitigate voltage violations in smart inverter enriched distribution network 

      Wagle, Raju; Sharma, Pawan; Charu, Sharma; Amin, Mohammad (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-30)
      Voltage violations are the main problem faced in distribution networks (DN) with a higher penetration of inverter-based generations (IBG). Active and reactive power control from smart inverters (SI) can mitigate such violations. Optimal power flow (OPF)-based control provides more accurate operating set points for the coordinated operation of SIs. Therefore, this paper presents a three-phase OPF-based ...
    • Optimal routing and charging procedures for electric buses 

      Masliakova, Kseniia (Master thesis; Mastergradsoppgave, 2016-04-06)
      The goal of the project is to use Ant Colony Optimization techniques with Genetic Algorithm to design and analyse routes and recharging schedules for electric buses. One system so-called “en route” charging was analysed where the bus applies a kind of pantograph at bus stops to recharge the bus batteries. This implies more frequent, but short recharging intervals. The program offers diff t variants ...
    • Optimal Solutions for Underwater Capacitive Power Transfer 

      Al-Sallami, Hussein; Hoff, Bjarte; Østrem, Trond (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-09)
      Capacitive power transfer (CPT) has attracted attention for on-road electric vehicles, autonomous underwater vehicles, and electric ships charging applications. High power transfer capability and high efficiency are the main requirements of a CPT system. This paper proposes three possible solutions to achieve maximum efficiency, maximum power, or conjugate-matching. Each solution expresses the ...
    • Optimal Volt Var control in Smart Distribution Networks 

      Shamraiz, Shamraiz (Master thesis; Mastergradsoppgave, 2021-05-24)
      Both the generation and transmission power networks are facing new threats and opportunities as the number of distributed energy resources (DERs) grows. Because of the high solar PV penetration, voltage rise and voltage volatility are becoming major problems in the distribution network. Voltage regulating devices (VRDs), such as on load tap changers (OLTCs), phase voltage regulators (SVRs), and ...