Viser treff 201-220 av 243

    • Modelling and simulating a hybrid electric vehicle 

      Leikarnes, Ivar Roskifte (Master thesis; Mastergradsoppgave, 2017-06-12)
      This thesis presents an overview of the different types of hybrid electric vehicle structures and basic guidelines regarding choice of components. The simulation model of a hybrid electric vehicle was created for this thesis to investigate the impact on fuel efficiency in relation to rolling resistance coefficient and vehicle weight. Although the model is not designed for optimal engine operation, ...
    • Transition to DC distribution grids 

      Awoniyi, Taiwo (Master thesis; Mastergradsoppgave, 2017-08-15)
      "The war between AC and DC has emerged once again due to the rapid development and advancement of electric power technologies. Nowadays, power electronics and DC/DC converters are able to change voltage levels, which could only be achieved by an AC transformer hundred years ago. Rising trend development of electric vehicle and renewable energy technology have led to an urgency for re-evaluation of ...
    • Intelligent load frequency control in an isolated wind-solar PV-micro turbine-diesel based micro-grid using V2G integration 

      Addisu, Wondwosen Eshetu (Master thesis; Mastergradsoppgave, 2017-06-12)
      Abstract Modern power systems need more intelligence and flexibility to maintain and control a generation load balance from subsequent serious disturbances due to the emerging of more renewable energy sources. This problem is becoming more significant today because of the increasing number of micro-grids (MGs). MGs usually use renewable energies in electrical production those fluctuate naturally. ...
    • DC distribution systems 

      Taso, Emir (Master thesis; Mastergradsoppgave, 2017-06-12)
      In today’s distribution system, the dominating type of current used is AC. In newer time, improvements have been done within the field of DC. The developments that are achieved, are in terms of converter efficiency and conversion capabilities. Along with development of DC equipment, the use and development of renewable energy sources have increased. This has brought up the topic of using DC in the ...
    • Design of a grid connected photovoltaic power electronic converter 

      Mustafa, Mohsin Noman (Master thesis; Mastergradsoppgave, 2017-06-12)
      In this thesis, the designing of a grid-connected photovoltaic system for the power electronic laboratory of UiT- Campus Narvik has been carried out. The relevant topics and literature regarding the elements in a photovoltaic system and grid connection standards have been studied and reviewed. A system with the capacity and ratings of solar modules currently available has been designed in Simulink. ...
    • Electric vehicles and vehicle-to-grid technology. How utilities can play a role 

      Tahir, Moez (Master thesis; Mastergradsoppgave, 2017-06-12)
      Adverse effects of fossil fuel burning internal combustion engine vehicles has alarmed nations worldwide. With recent technological advancements in electric vehicle industry, governments throughout the world are promoting wider adoption of electric vehicles to mitigate environmental issues. However, increasing popularity of electric vehicles will pose a great threat to existing electric grids due ...
    • FPGA-based data acquisition system for GNSS receiver for LEO-satellites applications 

      Siboniyo, Didier (Master thesis; Mastergradsoppgave, 2017-06-12)
      The modern Low Earth Orbit satellites (LEO-satellites) technology is highly complex and reliable than it was yesterday. Nowadays, the LEO-satellites applications extend from civilian to military applications. However, LEO-satellites require a Global Navigation Satellite System (GNSS) service, to achieve various tasks which require positioning and localizing. The challenge is to have a GNSS receiver ...
    • FPGA-based tracking system for GNSS receivers 

      Manandhar, Anil (Master thesis; Mastergradsoppgave, 2017-06-12)
      This report presents the design and simulation of code and carrier tracking system for a GNSS receiver. The GNSS receiver processes the signal sent by satellites in space. These signal contain carrier wave signal, ranging code and navigation data in encrypted form. To demodulate the navigation data, the processing block should accurately track the phase of incoming code and the frequency of incoming ...
    • Lagrangian and ALE Formulations For Soil Structure Coupling with Explosive Detonation 

      Souli, M; Albahkali, E; Shahrour, I; Moatamedi, Mojtaba (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      Simulation of Soil-Structure Interaction becomes more and more the focus of computational engineering in civil and mechanical engineering, where FEM (Finite element Methods) for soil and structural mechanics and Finite Volume for CFD (Computational Fluid Dynamics) are dominant. New advanced formulations have been developed for FSI (Fluid Structure Interaction) applications using ALE (Arbitrary ...
    • Stabilitet i 22kV distribusjonsnett 

      Skogvoll, Petter (Master thesis; Mastergradsoppgave, 2017-05-18)
      De senere årene har det vært en økning i utbygging av små produksjonsenheter i distribusjonsnettet. I dag benyttes distribusjonsnettet i hovedsak til å fordele kraft fra overliggende nett. En tilknytning av ny produksjon i slike nett vil medføre utfordringer for netteier når det gjelder spenningskvalitet og leveringssikkerhet og krever ofte oppgraderinger for å kunne opprettholde stabil og sikker ...
    • Some new Hardy-type inequalities in q-analysis 

      Baiarystanov, A.O.; Persson, Lars Erik; Shaimardan, S.; Temirkhanova, A. (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-09)
      We derive necessary and sufficient conditions (of Muckenhoupt-Bradley type) for the validity of q -analogs of (r, p) -weighted Hardy-type inequalities for all possible positive values of the parameters r and p . We also point out some possibilities to further develop the theory of Hardy-type inequalities in this new direction.
    • A new discrete Hardy-type inequality with kernels and monotone functions 

      Kalybay, Aigerim; Persson, Lars Erik; Temirkhanova, Ainur (Peer reviewed; Journal article; Tidsskriftartikkel, 2015-10-06)
      A new discrete Hardy-type inequality with kernels and monotone functions is proved for the case 1<q<p<∞1<q<p<∞. This result is discussed in a general framework and some applications related to Hölder’s summation method are pointed out.
    • Some new Hardy-type inequalities for Riemann-Liouville fractional q-integral operator 

      Persson, Lars Erik; Shaimardan, Serikbol (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-09-24)
      We consider the q-analog of the Riemann-Liouville fractional q-integral operator of order n∈Nn∈N. Some new Hardy-type inequalities for this operator are proved and discussed.
    • Time scale Hardy-type inequalities with ‘broken’ exponent p 

      Oguntuase, James A; Fabelurin, Olanrewaju O; Adeagbo-Sheikh, Abdulaziz G; Persson, Lars Erik (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-01-16)
      In this paper, some new Hardy-type inequalities involving ?broken? exponents are derived on arbitrary time scales. Our approach uses both convexity and superquadracity arguments, and the results obtained generalize, complement and provide refinements of some known results in literature
    • Asymptotics of a spectral-sieve problem 

      Amirat, Youcef; Bodart, Olivier; Chechkin, Gregory; Piatnitski, Andrey (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-11-18)
      In a bounded domain with a thin periodically punctured interface we study the limit behavior of the bottom of spectrum for a Steklov type spectral problem, the Steklov boundary condition being imposed on the perforation surface. For a certain range of parameters we construct the effective spectral problem and justify the convergence of eigenpairs.
    • Osmosis for non-electrolyte solvents in permeable periodic porous media 

      Heintz, Alexei; Piatnitski, Andrey (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016-08)
      The paper gives a rigorous description, based on mathematical homogenization theory, for flows of solvents with not charged solute particles under osmotic pressure for periodic porous media permeable for solute particles. The effective Darcy type equations for the flow under osmotic pressure distributed within the porous media are derived. The effective Darcy law contains an additional flux term ...
    • Singularly perturbed spectral problems with Neumann boundary conditions 

      Piatnitski, Andrey; Rybalko, A; Rybalko, V (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-09-07)
      The paper deals with the Neumann spectral problem for a singularly perturbed second-order elliptic operator with bounded lower order terms. The main goal is to provide a refined description of the limit behaviour of the principal eigenvalue and eigenfunction. Using the logarithmic transformation, we reduce the studied problem to an additive eigenvalue problem for a singularly perturbed Hamilton–Jacobi ...
    • Homogenization of random Navier–Stokes-type system for electrorheological fluid 

      Piatnitski, Andrey; Zhikov, Vasily (Peer reviewed; Journal article; Tidsskriftsartikkel, 2015-11-19)
      The paper deals with homogenization of Navier–Stokes-type system describing electrorheological fluid with random characteristics. Under non-standard growth conditions we construct the homogenized model and prove the convergence result. The structure of the limit equations is also studied.
    • A note on the maximal operators of Vilenkin-Nörlund means with non-increasing coefficients 

      Memić, Nacima; Persson, Lars Erik; Tephnadze, George; Kroo, A (Peer reviewed; Journal article; Tidsskriftsartikkel, 2016)
      In [14] we investigated some Vilenkin—Nörlund means with non-increasing coefficients. In particular, it was proved that under some special conditions the maximal operators of such summabily methods are bounded from the Hardy space H1/(1+α) to the space weak-L1/(1+α), (0 < α ≦ 1). In this paper we construct a martingale in the space H1/(1+α), which satisfies the conditions considered in [14], and so ...
    • Boundedness and compactness of a class of Hardy type operators 

      Abylayeva, AAkbota M; Oinarov, Ryskul; Persson, Lars Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-13)
      We establish characterizations of both boundedness and of compactness of a general class of fractional integral operators involving the Riemann-Liouville, Hadamard, and Erdelyi-Kober operators. In particular, these results imply new results in the theory of Hardy type inequalities. As applications both new and well-known results are pointed out.