Now showing items 21-40 of 57

    • 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 ...
    • 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 ...
    • 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 ...
    • One-dimensional model of turbulent flow of non-Newtonian drilling mud in non-prismatic channels 

      Welahettige, Prasanna Kumara Welahetti; Lundberg, Joachim; Bjerketvedt, Dag; Lie, Bernt; Vågsæther, Knut (Peer reviewed; Journal article, 2019)
      One-dimensional model of non-Newtonian turbulent flow in a non-prismatic channel is challenging due to the difficulty of accurately accounting for flow properties in the 1-D model. In this study, we model the 1-D Saint–Venant ...
    • OpenHPL for Modelling the Trollheim Hydropower Plant 

      Vytvytskyi, Liubomyr; Lie, Bernt (Peer reviewed; Journal article, 2019)
      An increase of tightly integrated, renewable energy sources with highly varying production leads to a greater need for flexible hydropower plants to “balance” the intermittent production from these sources. From a systems ...
    • Optimal design and operation of a UASB reactor for dairy cattle manure 

      Haugen, Finn; Bakke, Rune; Lie, Bernt; Hovland, Jon; Vasdal, Knut (Journal article; Peer reviewed, 2015-02-01)
      Optimal design and operation of a planned full-scale UASB reactor at a dairy farm are determined using optimization algorithms based on steady state simulations of a dynamic AD process model combined with models of the ...
    • Optimal Operation of the Peat Drying Process in Steam Tube Dryers 

      Kulakovsky, Leonid; Rosen, Victor; Sharma, Roshan; Pfeiffer, Carlos Fernando; Lie, Bernt (Conference object; Peer reviewed, 2015-11-25)
      Ukraine is an energy-dependent country and aims to reduce the import of natural gas, heat, and power in general. This implies extracting fuel from her own natural resources; one relevant and readily available energy carrier ...
    • Oxygen Effects in Anaerobic Digestion II 

      Botheju, Deshai; Lie, Bernt; Bakke, Rune (Journal article, 2010)
      Standard models describing bio-gasification using anaerobic digestion do not include necessary processes to describe digester dynamics under the conditions of oxygen presence. Limited oxygenation in anaerobic digestion can ...