Now showing items 21-40 of 62

    • Flow regime changes at hydraulic jumps in an open Venturi channel for Newtonian fluid 

      Welahettige, Prasanna Kumara Welahetti; Lie, Bernt; Vågsæther, Knut (Journal article; Peer reviewed, 2017)
    • Hybrid Machine Learning and Mechanistic Thermal Model of Synchronous Generator 

      Dhakal, Prakash (Master thesis, 2021)
      Overheating of synchronous generators may result in shortened generator lifespan, thus strict constraints are imposed on their operation. A dynamic model of the generator temperature may leave good monitoring of the generator ...
    • Hydropower Systems: Comparison of Mechanistic and Table Look-up Turbine Models 

      Splavska, Valentyna; Vytvytskyi, Liubomyr; Lie, Bernt (Journal article; Peer reviewed, 2017)
      In this paper, a detailed overview of hydropower system components is given. Components of the system include intake race, upstream and downstream surge tanks, penstock, turbine and draft tube. A case study which includes ...
    • Improved model for solar heating of buildings 

      Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      A considerable future increase in the global energy use is expected, and the effects of energy conversion on the climate are already observed. Future energy conversion should thus be based on resources that have negligible ...
    • Improved Oil Recovery through Advanced Control 

      Bhattarai, Ashish (Master thesis, 2021)
      Norway is one of the major suppliers of oil and gas to the world market. Revenues from sales of oil and gas have played an important role in building modern Norwegian society. Oil and gas are trapped in the subsurface ...
    • Linearization for Analysis of a Hydropower Model using Python API for OpenModelica 

      Vytvytskyi, Liubomyr; Lie, Bernt (Journal article; Peer reviewed, 2018)
      Even though almost all processes in the real world are described by nonlinear models, nonlinear theory for analysis of these models is far less developed than the theory for linear models. Therefore model linearization is ...
    • Machine Learning in Python for Weather Forecast based on Freely Available Weather Data 

      Abrahamsen, Erik Boye; Brastein, Ole Magnus; Lie, Bernt (Journal article; Peer reviewed, 2018)
      Forecasting weather conditions is important for, e.g., operation of hydro power plants and for flood management. Mechanistic models are known to be computationally demanding. Hence, it is of interest to develop models that ...
    • Model based control for run-of-river system. Part 1: Model implementation and tuning 

      Vytvytskyi, Liubomyr; Sharma, Roshan; Lie, Bernt (Journal article; Peer reviewed, 2015)
      Optimal operation and control of a run-of-river hydro power plant depends on good knowledge of the elements of the plant in the form of models. River reaches are often considered shallow channels with free surfaces. A ...
    • Model based control for run-of-river system. Part 2: Comparison of control structures 

      Vytvytskyi, Liubomyr; Sharma, Roshan; Lie, Bernt (Journal article; Peer reviewed, 2015)
      Optimal operation and control of a run-of-river hydro power plant depend on good knowledge of the elements of the plant in the form of models. Both the control architecture of the system, i.e. the choice of inputs and ...
    • Model Based Early Kick/Loss Detection and Attenuation with Topside Sensing in Managed Pressure Drilling 

      Jinasena, Asanthi; Holta, Haavard H. F.; Jondahl, Morten Hansen; Welahettige, Prasanna Kumara Welahetti; Aamo, Ole Morten; Sharma, Roshan; Viumdal, Håkon; Lie, Bernt (Peer reviewed; Journal article, 2020)
      Early kick/loss detection is a crucial part of safe well control, and it plays a major role in the reduction of risk and non-productive time in drilling. In conventional drilling, topside sensing is used for early kick/loss ...
    • Modeling and Simulation of Triclosan Kinetics and Distribution in Humans Using a PBPK Model 

      Maharjan, Samee; Sharma, Roshan; Husøy, Trine; Dirven, Hubert; Andreassen, Monica; Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      Personal care products (PCPs) such as soaps, perfumes, toothpastes, lotions, etc. contain various chemicals. Triclosan (TCS) is widely used as an antibacterial additive in PCPs. Traces of TCS are found in human plasma and ...
    • Modeling and Simulation of Triclosan Kinetics and Distribution in Humans Using PBPK Model 

      Cascella, Vincenza; Andreassen, Monica; Husøy, Trine; Dirven, Hubert; Lie, Bernt (Journal article; Peer reviewed, 2018)
      Triclosan (TCS) has been used as an antibacterial additive in several personal care products (PCPs) for more than 40 years. In animals studies, it is observed that TCS in rats has adverse effects on the endocrine function ...
    • Modeling for control of run-of-river power plant Grønvollsfoss 

      Vytvytskyi, Liubomyr; Sharma, Roshan; Granstrøm, Ingunn; Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      Design of optimal operation and control of a run-of-river hydro power plant depends on good models for the elements of the plant. River reaches are often considered to be shallow channels with free surface flow. A typical ...
    • Modelling and control of a typical high head hydropower plant 

      Zhou, Wenjing; Lie, Bernt; Glemmestad, Bjørn (Conference object; Peer reviewed, 2011)
      This paper describes an effective mathematical model of a hydropower plant and how a decentralized control strategy for frequency and terminal voltage can be simulated. Several dynamic equations are presented for each ...
    • Models for control of thermal energy in buildings 

      Johansen, Casper Amandus; Lie, Bernt; Skeie, Nils-Olav (Peer reviewed; Journal article, 2019)
      A large fraction of the world’s energy production is used for HVAC in buildings. It is therefore important to develop improved strategies for ef?cient use of energy in buildings. Storage of intermittent energy production ...
    • NEQ rate based modeling of an absorption column for post combustion CO2 capturing 

      Jayarathna, Sanoja A.; Lie, Bernt; Melaaen, Morten Christian (Journal article; Peer reviewed, 2011-04-01)
      Post combustion CO2 capture via absorption into aqueous alkanolamine systems is considered to be the most mature and potential technique for CO2 removal from the power plants' exhaust gases. Modeling and simulation of such ...
    • Nonlinear observer for hydropower system 

      Vytvytskyi, Liubomyr; Sharma, Roshan; Lie, Bernt (Peer reviewed; Journal article, 2019)
      Estimation of unmeasured states plays an essential role in the design of control systems as well as for monitoring of hydropower plants. The standard Kalman filter gives the optimum state estimates for linear systems. ...
    • Numerical solution of the Saint Venant equation for Non-Newtonian fluid 

      Agu, Cornelius Emeka; Lie, Bernt (Conference object; Peer reviewed, 2014)
      Non-Newtonian fluid flow through a Venturi channel is studied using the Saint Venant equation. The nonlinear hyperbolic equation is numerically tricky to solve, therefore in this study, we consider the finite volume method ...
    • OMJulia: An OpenModelica API for Julia-Modelica Interaction 

      Lie, Bernt; Palanisamy, Anandhakumar; Mengist, Alachew; Buffoni, Lena; Sjölund, Martin; Asghar, Adeel; Pop, Adrian; Fritzson, Peter (Peer reviewed; Journal article, 2019)
      Modelica is an object oriented, acausal equation-based language for describing complex, hybrid dynamic models. About ten Modelica implementations exist, of which most are commercial and two are open source; the implementations ...
    • On-Off and PI control of methane gas production of a pilot anaerobic digestion reactor 

      Haugen, Finn; Bakke, Rune; Lie, Bernt (Journal article; Peer reviewed, 2013)
      A proposed feedback control system for methane flow control of a real pilot anaerobic digestion reactor fed with dairy waste is designed and analyzed using the modified Hill model, which has previously been adapted to the ...