• A Framework for Fault Diagnosis in Managed Pressure Drilling Applied to Flow-Loop Data 

      Willersrud, Anders; Imsland, Lars Struen; Pavlov, Alexey; Kaasa, Glenn-Ole (Journal article; Peer reviewed, 2013)
      Data from a medium-scale horizontal flow loop test facility is used to test fault diagnosis in managed pressure drilling. The faults are downhole incidents such as formation influx, fluid loss, drillstring washout, pack-off, ...
    • A study on an iceberg drift trajectory 

      Andersson, Leif Erik; Scibilia, Francesco; Imsland, Lars Struen (Chapter, 2017)
      Iceberg drift forecast is a challenging process. Large uncertainties in iceberg geometry and in the driving forces — current, wind and waves — make accurate forecasts difficult. This article illustrates from a data set ...
    • Adaptive approximation-based estimation of downhole pressure in managed pressure drilling 

      Imsland, Lars Struen; Kaasa, Glenn-Ole (Journal article; Peer reviewed, 2012)
      Low-complexity multi-model algorithms for adaptive bottomhole pressure estimation in drilling is derived, and theoretical and practical conditions for convergence (persistency of excitation) discussed, assuming a) topside ...
    • An estimation-forecast set-up for iceberg drift prediction 

      Andersson, Leif Erik; Scibilia, Francesco; Imsland, Lars Struen (Journal article; Preprint, 2016)
      Iceberg drift forecasting is challenging. Large uncertainties in iceberg geometry and in iceberg driving forces – current, wind and waves – make accurate forecasts difficult. In this work, a new estimation-forecast scheme ...
    • An iceberg forecast approach based on a statistical ocean current model 

      Andersson, Leif Erik; Scibilia, Francesco; Imsland, Lars Struen (Journal article; Peer reviewed, 2019)
      This article proposes a statistical model for short-term iceberg drift forecasts by transforming the problem of forecasting the iceberg velocity into a problem of forecasting the ocean current velocity. A Vector-autoregression ...
    • Analysis of Iceberg Drift Trajectories Using the Multivariate Empirical Mode Decomposition 

      Andersson, Leif Erik; Scibilia, Francesco; Copland, Luke; Aftab, Muhammad Faisal; Imsland, Lars Struen (Journal article; Peer reviewed, 2018)
      In this study we show how to detect and extract the tidal and inertial oscillation from iceberg velocity data by using the multivariate empirical model decomposition. Due to the similar frequencies of both oscillations in ...
    • Asset fleet management in the process industry - a conceptual model 

      Spuntrup, F Schulze; Imsland, Lars Struen (Journal article; Peer reviewed, 2018)
      Fleet Management is widely known from vehicle fleet management. However, this term is not elaborated in more detail for the management of asset fleets in the process industries. Since the challenges and the potential ...
    • Autonomous Aerial Ice Observation for Ice Defense 

      Haugen, Joakim; Imsland, Lars Struen (Journal article; Peer reviewed, 2014)
      One of the tasks in ice defense is to gather information about the surrounding ice environment using various sensor platforms. In this manuscript we identify two monitoring tasks known in literature, namely dynamic coverage ...
    • Block factorization of step response model predictive control problems 

      Kufoalor, D. Kwame Minde; Frison, Gianluca; Imsland, Lars Struen; Johansen, Tor Arne; Jørgensen, JB (Journal article; Peer reviewed, 2017)
      By introducing a stage-wise prediction formulation that enables the use of highly efficient quadratic programming (QP) solution methods, this paper expands the computational toolbox for solving step response MPC problems. ...
    • Campaign-based modeling for degradation evolution in batch processes using a multiway partial least squares approach 

      Wu, Ouyang; Bouaswaig, Ala; Imsland, Lars Struen; Schneider, Stefan; Roth, Matthias; Moreno Leira, Fernando (Journal article; Peer reviewed, 2019)
      In the process industry, various types of degradation occur in processing plants, resulting in significant economic losses. Modeling of degradation is important because it provides quantitative insights for consideration ...
    • Combined Optimal Control and Combinatorial Optimization for Searching and Tracking Using an Unmanned Aerial Vehicle 

      Albert, Anders; Imsland, Lars Struen (Journal article; Peer reviewed, 2018)
      Combined searching and tracking of objects using Unmanned Aerial Vehicles (UAVs) is an important task with many applications. One way to approach this task is to formulate path-planning as a continuous optimal control ...
    • Comparison of statistical iceberg forecast models 

      Andersson, Leif Erik; Scibilia, Francesco; Copland, Luke; Imsland, Lars Struen (Journal article; Peer reviewed, 2018)
      Short-term iceberg drift prediction is challenging. Large uncertainties in the driving forces – current, wind and waves – usually prevent accurate forecasts. Recently several statistical iceberg forecast models have been ...
    • Constrained Posterior Cramér-Rao Bound for Discrete-Time Systems 

      Andersson, Leif Erik; Brekke, Edmund Førland; Imsland, Lars Struen; Scibilia, Francesco (Journal article, 2017)
      This article presents a Cramér-Rao lower bound for the discrete-time filtering problem under linear state constraints. A simple recursive algorithm is presented that extends the computation of the Cramér-Rao lower bound ...
    • Coordinated Control of Multiple HVDC links using backstepping 

      Ersdal, Anne Mai; Imsland, Lars Struen; Uhlen, Kjetil (Journal article, 2012)
      This article regards a power system containing multiple High Voltage Direct Current (HVDC) links. The topic is to exploit the HVDC lines’ ability to control the power supplied by them to increase the stability of the system. ...
    • Data-driven degradation model for batch processes: a case study on heat exchanger fouling 

      Wu, Ouyang; Bouaswaig, Ala; Schneider, Stefan; Leira, Fernando; Imsland, Lars Struen; Roth, Matthias (Journal article; Peer reviewed, 2018)
    • Design and Experimental Validation of Nonlinear Infinite-Dimensional Adaptive Observer in Automated Managed Pressure Drilling 

      Hasan, Agus Ismail; Imsland, Lars Struen; Hauge, Espen (Journal article; Peer reviewed, 2017)
      Utilizing flow rate and pressure data in and out of the fluid circulation loop provides a driller with real-time trends for early detection of well-control problems that impact the drilling efficiency. Due to limited number ...
    • Drillstring Washout Diagnosis using Friction Estimation and Statistical Change Detection 

      Willersrud, Anders; Blanke, Mogens; Imsland, Lars Struen; Pavlov, Alexey K. (Journal article; Peer reviewed, 2015)
      In oil and gas drilling, corrosion or tensile stress can give small holes in the drillstring, which can cause leakage and prevent sufficient flow of drilling fluid. If such \emph{washout} remains undetected and develops, ...
    • Dynamic Real-Time Optimisation of a CO2 Capture Facility 

      Hotvedt, Mathilde; Hauger, Svein Olav; Gjertsen, Fredrik; Imsland, Lars Struen (Journal article; Peer reviewed, 2019)
      This work investigates economic optimisation of an energy-intensive amine regeneration process in a post-combustion CO2 capture plant, subject to a minimum CO2 capture ratio over 24 hours. A Dynamic Real-Time Optimisation ...
    • Early pack-off diagnosis in drilling using an adaptive observer and statistical change detection 

      Willersrud, Anders; Imsland, Lars Struen; Blanke, Mogens (Journal article, 2015)
      Pack-off is a partially or complete blocking of the circulation flow in oil and gas drilling, which can lead to costly delays. Early detection and localization of a pack-off is crucial in order to take necessary actions ...
    • Echo State Networks for Virtual Flow Metering in Gravity Separator 

      Vonen, Sivert (Master thesis, 2019)
      Virtuell volumstrøm estimering (Virtual Flow Metering, VFM), er et begrep som innebærer å estimere volumraten for de ulike fasene i en fler-fase volumstrøm uten å måle de direkte. Istedenfor så brukes data som er relatert ...