• 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 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 ...
    • Analysis and Optimization of Sinus Lifting in Snake Robots 

      Sue-Chu, Christine Maria (Master thesis, 2013)
      Snake robots have been around for decades. The study on snake robots started in 1946 when Gray performed a mathematical analysis on the biological snake. Hirose followed his course and developed the world's first snake ...
    • Applied Nonlinear Compressor Control with Gain Scheduling and State Estimation 

      Tengesdal, Njål; Kristoffersen, Torstein Thode; Holden, Christian (Journal article; Peer reviewed, 2018)
      Subsea gas compressors are key components for both increased and accelerated hydrocarbon production. Compressors enable the development of fields that are remote, in deep waters, or have low and/or reduced reservoir pressure. ...
    • Completion of Compact Separator Laboratory 

      Hellem, Magnus; Djupvik, Jens (Master thesis, 2017)
      As the petroleum business explore deeper waters and more remote locations in the quest for new hydrocarbon reservoirs, challenges that were not that relevant in earlier years now become more common. To face these challenges, ...
    • Component-Based Modeling and Simulation of Nonlinear Drill-String Dynamics 

      Tengesdal, Njål Kjærnes; Holden, Christian; Pedersen, Eilif (Chapter, 2019)
      In this paper, we present a dynamic model for a generic drill-string. The model is developed with the intention for component-based simulation with coupling to external subsystems. The performance of the drill-string is ...
    • 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 ...
    • Finalizing the Wet Gas Laboratory 

      Nedregård, Daniel (Master thesis, 2017)
      This report describes the final stages of development for the small scale wet gas compression test lab. The lab is located at the MTP Institute at NTNU in Trondheim, and it is built in the workshop at campus Valgrinda. The ...
    • 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 Control of Parametric Roll Resonance 

      Holden, Christian (Doctoral Theses at NTNU, 1503-8181; 2011:174, Doctoral thesis, 2011)
      Parametric roll resonance is a dangerous resonance phenomenon affecting several types of ships, such as destroyers, RO-RO paxes, cruise ships, fishing vessels and especially container ships. Worst case, parametric roll is ...
    • 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 ...
    • Modelling and Control of Anti-Roll Tanks 

      Hildrestrand, Jon Robert Seth (Master thesis, 2010)
      A ship out at sea is exposed to environmental forces in addition to those generated by the ship's actuators. It is these forces that make the ship move. However, in some cases the ship moves in an undesirable way. Because ...
    • Modelling and Control of Dry and Wet Gas Compressors 

      Tengesdal, Njål (Master thesis, 2017)
      Performing gas compression subsea is an important component for future realisation of complete subsea processing facilities. Gas compressors operating with raw well fluids, categorised as wet gas, enables an increase in ...
    • Modelling and nonlinear control of a wet gas centrifugal compressor 

      Kristoffersen, Torstein Thode; Holden, Christian (Chapter, 2018)
      Production of gas condensate from small and remote gas condensate fields require cost-efficient boosting technology for maintaining an economically satisfactory throughput. Wet gas compressors are a new boosting technology ...
    • Nonlinear state and parameter estimation of a gas-liquid cylindrical cyclone 

      Kristoffersen, Torstein Thode; Holden, Christian (Chapter, 2018)
      — New offshore oil and gas discoveries are located at deep waters with long tie-back distances. Development of such fields require compact gas-liquid separation technologies. Efficient operation of such separators require ...
    • Optimal Dynamic Force Mapping for Obstacle-Aided Locomotion in 2D Snake Robots 

      Holden, Christian; Stavdahl, Øyvind; Gravdahl, Jan Tommy (Journal article; Peer reviewed, 2014)
      Snake robots are biomimetic robots highly suited for traversing challenging terrain where traditional robots have difficulty moving. A key aspect is obstacle-aided locomotion, where the snake pushes against the environment ...