Blar i Institutt for maskinteknikk og produksjon på forfatter "Ohrem, Sveinung Johan"

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    • A Comparison of Hazards and Efficiencies of Conventional and Adaptive Control Algorithms Using Systems-Theoretic Process Analysis 

      Ohrem, Sveinung Johan; Kim, Hyungju; Lundteigen, Mary Ann; Holden, Christian (Journal article; Peer reviewed, 2019)
      Control systems are an important and increasingly complex part of most industrial and non-industrial systems. As such, identifying and handling associated risks is increasingly important. Systems- Theoretic Process Analysis ...

    • Adaptive Control of Subsea Processes 

      Ohrem, Sveinung Johan (Doctoral theses at NTNU;2019:217, Doctoral thesis, 2019)

    • Adaptive controller and observer design using open and closed-loop reference models for linear time-invariant systems with unknown dynamics 

      Ohrem, Sveinung Johan; Holden, Christian (Peer reviewed; Journal article, 2021)
      This article presents an output feedback controller and observer design approach for linear time-invariant systems with unknown dynamics. The presented method uses an open-loop reference model to generate the desired ...

    • Adaptive Feedback Linearizing Control of a Gas Liquid Cylindrical Cyclone 

      Ohrem, Sveinung Johan; Kristoffersen, Torstein Thode; Holden, Christian (Chapter, 2017)
      As subsea production of oil and gas reaches deeper and more remote waters, the need for more compact separation equipment arises. The gas hquid cylindrical cyclone (GLCC) is a widely used separation device in topside ...

    • Controller and observer design for first order LTI systems with unknown dynamics 

      Ohrem, Sveinung Johan; Holden, Christian (Chapter, 2018)
      The design of controllers and observers often relies on first order models of the system in question. These models are often obtained either through step-response tests, through on-line or off-line identification, or through ...

    • Controller Design and Control Structure Analysis for a Novel Oil–Water Multi-Pipe Separator 

      Ohrem, Sveinung Johan; Skjefstad, Håvard Slettahjell; Stanko, Milan; Holden, Christian (Journal article; Peer reviewed, 2019)
      To enable more efficient production of hydrocarbons on the seabed in waters where traditional separator equipment is infeasible, the offshore oil and gas industry is leaning towards more compact separation equipment. A ...

    • Design of Compact Separator Laboratory 

      Ellefsen, Andre Listou; Aasen, Emil Yde (Master thesis, 2016)
      Most of the easily accessible offshore oil and gas resources have been developed. As a result of this, subsea production and processing has over the last decade been regarded as the future of the offshore oil and gas ...

    • L1 Adaptive Anti-Slug Control 

      Ohrem, Sveinung Johan; Holden, Christian; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2017)
      In many multiphase pipeline-riser systems, anti-slug control is necessary to ensure steady and optimal operation. In this paper, we propose using an ℒ1 adaptive controller as an augmentation to standard PI control to ...

    • Model-Based and Model-Free Optimal Control of a Gas Liquid Cylindrical Cyclone 

      Ohrem, Sveinung Johan; Kristoffersen, Torstein Thode; Holden, Christian (Journal article; Peer reviewed, 2018)
      Optimal control is important in the oil and gas industry, where small changes of process variables may have significant economical, environmental and safety impacts. Finding the optimal setpoint for a controlled variable ...

    • Modeling and nonlinear model predictive control of a subsea pump station 

      Ohrem, Sveinung Johan; Holden, Christian (Journal article; Peer reviewed, 2017)
      In this paper we present a model of a pump station consisting of two pumps in parallel with a recycle line, and a nonlinear Model Predictive Control strategy for said pump station with suction pressure as the controlled ...

    • Robust adaptive backstepping DP control of ROVs 

      Ohrem, Sveinung Johan; Amundsen, Herman Biørn; Caharija, Walter; Holden, Christian (Peer reviewed; Journal article, 2022)
      Dynamic positioning is an important control feature for an underwater remotely operated vehicle. This paper presents a nonlinear dynamic positioning controller suited for application to vehicles with model uncertainties, ...