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  • 51.
    Carlsson, Bengt
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Fault detection and isolation of sensors in aeration control systems2014Inngår i: Proc. IWA World Water Congress: 2014, IWA Publishing, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we consider the problem of fault detection and isolation in the aeration system of an activated sludge process. The purpose is to detect and localize possible faults in dissolved oxygen and air flow sensors. The dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for a fault detection algorithm we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model nº 1 by Monte Carlo simulations, and using data from a wastewater treatment plant. The fault detection method shows good results for a correct and early fault detection and isolation.

  • 52.
    Carlsson, Bengt
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Fault detection of sensors in aeration control systems: the airflow ratio method2013Inngår i: 11th IWA conference on Instrumentation, Control and Automation, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A fault detection method, ARM, has been proposed for detection of faults in DOsensors in a serie of aerated zones. The DO in each zone is assumed to be controlled. In a simulation study, ARM shows promising results for correct and early fault detection. Eventually, it will not be possible to distinguish between a fault in a DOsensor and in air flow rate sensor. In this study, we have, for simplicity, used KLa as a measure of the air flow rate. In practice an air flow rate sensor should be used. An interesting alternative is to use the air valve position instead of the airflow rate.

  • 53.
    Carlsson, Bengt
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åmand, Linda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Long-term evaluation of full-scale ammonium control in three large WWTPs2013Inngår i: 11th IWA conference on Instrumentation, Control and Automation, 2013Konferansepaper (Fagfellevurdert)
  • 54.
    Carlsson, Bengt
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åmand, Linda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Parameter scheduling in ammonium feedback control2013Inngår i: 11th IWA conference on Instrumentation, Control and Automation, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Parameter scheduling is a method to change controller settings depending on the process state. This study investigates the feasibility for parameter scheduling in a number of ammonium feedback strategies to improve disturbance rejection during peak load events. The controllers investigated by simulation are fast ammonium control, floating ammonium control and a moving average controller. A controller similar to the floating ammonium controller is also tested in a full-scale plant. The scheduling changes the upper bound on the DO set-point or the controller gain and integral time when effluent ammonium reaches a specified level. By this scheduling strategy the average ammonium concentration is decreased by up to 9%. The moving average controller showed the most promising results, but the results depend on the dissolved oxygen half saturation constant.

  • 55.
    Cassel, Sofia
    et al.
    Scania CV AB, Sodertalje, Sweden.
    Howar, Falk
    Dortmund Univ Technol, Dortmund, Germany;Fraunhofer ISST, Dortmund, Germany.
    Jonsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Steffen, Bernhard
    TU Dortmund, Chair Programming Syst, Dortmund, Germany.
    Extending Automata Learning to Extended Finite State Machines2018Inngår i: Machine Learning for Dynamic Software Analysis: Potentials and Limits / [ed] Bennaceur, A Hahnle, R Meinke, K, Springer, 2018, s. 149-177Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Automata learning is an established class of techniques for inferring automata models by observing how they respond to a sample of input words. Recently, approaches have been presented that extend these techniques to infer extended finite state machines (EFSMs) by dynamic black-box analysis. EFSMs model both data flow and control behavior, and their mutual interaction. Different dialects of EFSMs are widely used in tools for model-based software development, verification, and testing. This survey paper presents general principles behind some of these recent extensions. The goal is to elucidate how the principles behind classic automata learning can be maintained and guide extensions to more general automata models, and to situate some extensions with respect to these principles.

  • 56.
    Cedervall, Ylva
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Geriatrik.
    Halvorsen, Kjartan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åberg, Anna Cristina
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Geriatrik.
    A longitudinal study of gait function and characteristics of gait disturbances in individuals with Alzheimer's disease2014Inngår i: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 39, nr 4, s. 1022-1027Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Walking in daily life places high demands on the interplay between cognitive and motor functions. A well-functioning dual-tasking ability is thus essential for walking safely. The aims were to study longitudinal changes in gait function during single- and dual-tasking over a period of two years among people with initially mild AD (n = 21). Data were collected on three occasions, twelve months apart. An optical motion capture system was used for three-dimensional gait analysis. Gait parameters were examined at comfortable gait speed during single-tasking, dual-tasking naming names, and naming animals. The dual-task cost for gait speed was pronounced at baseline (names 26%, animals 35%), and remained so during the study period. A significant (p < 0.05) longitudinal decline in gait speed and step length during single- and dual-tasking was observed, whereas double support time, step width and step height showed inconsistent results. Systematic visual examination of the motion capture files revealed that dual-tasking frequently resulted in gait disturbances. Three main characteristics of such disturbances were identified: Temporal disturbance, Spatial disturbance and Instability in single stance. These aberrant gait performances may affect gait stability and increase the risk of falling. Furthermore, the observed gait disturbances can contribute to understanding and explaining previous reported gait variability among individuals with AD. However, the role that dual-task testing and aberrant dual-task gait performance play in the identification of individuals with early signs of cognitive impairment and in predicting fall risk in AD remains to be studied.

  • 57.
    Chistiakova, Tatiana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Ammonium based aeration control in wastewater treatment plants: Modelling and controller design2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Wastewater treatment involves many processes and methods which make a treatment plant a large-scaled and complex system. A fundamental challenge is how to maintain a high process efficiency while keeping the operational costs low. The variety in plant configurations, the nonlinear behaviour, the large time delays and saturations present in the system contribute to making automation and monitoring a demanding task.

    The biological part of a wastewater treatment process includes an aeration of the water and this process has been shown to often result in the highest energy consumption of the plant. Oxygen supply is a fundamental part of the activated sludge process used for aerobic microorganisms growing. The concentration of the dissolved oxygen should be high enough to maintain a sufficient level of biological oxidation. However, if the concentration is too high the process efficiency is significantly reduced leading to a too high energy consumption. Hence, there are two motivations behind the aeration control task: process efficiency and economy. One of the possible strategies to adjust the dissolved oxygen level in a nitrifying activated sludge process is to use ammonium feedback measurements.

    In this thesis, an activated sludge process is modelled and analysed in terms of dissolved oxygen to ammonium dynamics. First, the data obtained from a simplified Benchmark Simulation Model no.1 was used to identify the system. Both linear and nonlinear models were evaluated. A model with a Hammerstein structure where the nonlinearity was described by a Monod function was chosen for a more thorough study. Here, a feedback controller was designed to achieve L2-stability. The stability region was pre-computed to determine the maximum allowed time delay for the closed loop system. Finally, a feedforward controller was added to the system, and shown to significantly improve the disturbance rejection properties.

    Delarbeid
    1. Nonlinear system identification of the dissolved oxygen to effluent ammonia dynamics in an activated sludge process
    Åpne denne publikasjonen i ny fane eller vindu >>Nonlinear system identification of the dissolved oxygen to effluent ammonia dynamics in an activated sludge process
    2017 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Serie
    IFAC-PapersOnLine, ISSN 2405-8963 ; 50:1
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-334208 (URN)10.1016/j.ifacol.2017.08.365 (DOI)000423964800149 ()
    Konferanse
    IFAC 2017, July 9–14, Toulouse, France
    Tilgjengelig fra: 2017-10-18 Laget: 2017-11-21 Sist oppdatert: 2018-11-29bibliografisk kontrollert
    2. Non-linear modelling of the dissolved oxygen to ammonium dynamics in a nitrifying activated sludge process
    Åpne denne publikasjonen i ny fane eller vindu >>Non-linear modelling of the dissolved oxygen to ammonium dynamics in a nitrifying activated sludge process
    2017 (engelsk)Inngår i: Proc. 12th IWA Specialized Conference on Instrumentation, Control and Automation, 2017, s. 85-93Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-334201 (URN)
    Konferanse
    ICA2017, June 11–14, Québec, Canada
    Tilgjengelig fra: 2017-06-14 Laget: 2017-11-21 Sist oppdatert: 2018-08-17bibliografisk kontrollert
    3. Input–output stability design of an ammonium based aeration controller for wastewater treatment
    Åpne denne publikasjonen i ny fane eller vindu >>Input–output stability design of an ammonium based aeration controller for wastewater treatment
    2018 (engelsk)Inngår i: Proc. American Control Conference: ACC 2018, American Automatic Control Council , 2018, s. 2964-2971Konferansepaper, Publicerat paper (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    American Automatic Control Council, 2018
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-349422 (URN)10.23919/ACC.2018.8431151 (DOI)978-1-5386-5428-6 (ISBN)
    Konferanse
    ACC 2018, June 27–29, Milwaukee, WI
    Tilgjengelig fra: 2018-08-16 Laget: 2018-04-27 Sist oppdatert: 2018-08-27bibliografisk kontrollert
  • 58.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Non-linear modelling of the dissolved oxygen to ammonium dynamics in a nitrifying activated sludge process2017Inngår i: Proc. 12th IWA Specialized Conference on Instrumentation, Control and Automation, 2017, s. 85-93Konferansepaper (Fagfellevurdert)
  • 59.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Samuelsson, Oscar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Binary classifiers applied to detect DO sensor faults during washing events2015Inngår i: Proc. 2nd IWA Conference on New Developments in IT & Water, IWA Publishing, 2015Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper, several classication techniques are applied for monitoring the status of DO sensors in wastewater treatment plants. In particular, DO sensors during washing events are studied and indication parameters from these events are used. The methods considered are the following: k-Nearest Neighbours, Radial Basis Function and Random Forest classiers. The result shows the comparison and the eligibility of the methods to detect a clogged DO-sensor.

  • 60.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Mattsson, Per
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Nonlinear system identification of the dissolved oxygen to effluent ammonia dynamics in an activated sludge process2017Konferansepaper (Fagfellevurdert)
  • 61.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Mattsson, Per
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Nonlinear system identification of the dissolved oxygen to effluent ammonium dynamics in an activated sludge process2018Rapport (Annet vitenskapelig)
  • 62.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Combined L2-stable feedback and feedforward aeration control in a wastewater treatment plant2019Inngår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865, Vol. 27Artikkel i tidsskrift (Fagfellevurdert)
  • 63.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Input–output stability design of an ammonium based aeration controller for wastewater treatment2018Inngår i: Proc. American Control Conference: ACC 2018, American Automatic Control Council , 2018, s. 2964-2971Konferansepaper (Fagfellevurdert)
  • 64.
    Chistiakova, Tatiana
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Application of machine learning methods for fault detection in wastewater treatment plants2014Inngår i: Reglermöte, 2014Konferansepaper (Annet vitenskapelig)
  • 65. Churilov, Alexander
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Mattsson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Periodical solutions in a pulse-modulated model of endocrine regulation with time-delay2014Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 59, nr 3, s. 728-733Artikkel i tidsskrift (Fagfellevurdert)
  • 66. Churilov, Alexander
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Shepeljavyi, Alexander
    A state observer for continuous oscillating systems under intrinsic pulse-modulated feedback2012Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 48, nr 6, s. 1117-1122Artikkel i tidsskrift (Fagfellevurdert)
  • 67. Churilov, Alexander
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Shepeljavyi, Alexander
    Further Results on a State Observer for Continuous Oscillating Systems under Intrinsic Pulsatile Feedback2011Inngår i: Proc. 50th Conference on Decision and Control, Piscataway, NJ: IEEE , 2011Konferansepaper (Fagfellevurdert)
  • 68. Churilov, Alexander
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Shepeljavyi, Alexander
    State observer for continuous oscillating systems with pulsatile feedback2011Inngår i: Proc. 18th IFAC World Congress, International Federation of Automatic Control , 2011Konferansepaper (Fagfellevurdert)
  • 69. Churilov, Alexander N.
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    An impulse-to-impulse discrete-time mapping for a time-delay impulsive system2014Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 50, nr 8, s. 2187-2190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown that an impulsive system with a time-delay in the continuous part can be equivalently represented by discrete dynamics under less restrictive conditions on the time-delay value than considered previously.

  • 70. Churilov, Alexander N.
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Discrete-time map for an impulsive Goodwin oscillator with a distributed delay2016Inngår i: MCSS. Mathematics of Control, Signals and Systems, ISSN 0932-4194, E-ISSN 1435-568X, Vol. 28, nr 1, artikkel-id 9Artikkel i tidsskrift (Fagfellevurdert)
  • 71. Churilov, Alexander N.
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zhusubaliyev, Zhanybai T.
    Discrete-time mapping for an impulsive Goodwin oscillator with three delays2017Inngår i: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering, ISSN 0218-1274, Vol. 27, nr 12, artikkel-id 1750182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A popular biomathematics model of the Goodwin oscillator has been previously generalized to a more biologically plausible construct by introducing three time delays to portray the transport phenomena arising due to the spatial distribution of the model states. The present paper addresses a similar conversion of an impulsive version of the Goodwin oscillator that has found application in mathematical modeling, e.g. in endocrine systems with pulsatile hormone secretion. While the cascade structure of the linear continuous part pertinent to the Goodwin oscillator is preserved in the impulsive Goodwin oscillator, the static nonlinear feedback of the former is substituted with a pulse modulation mechanism thus resulting in hybrid dynamics of the closed-loop system. To facilitate the analysis of the mathematical model under investigation, a discrete mapping propagating the continuous state variables through the firing times of the impulsive feedback is derived. Due to the presence of multiple time delays in the considered model, previously developed mapping derivation approaches are not applicable here and a novel technique is proposed and applied. The mapping captures the dynamics of the original hybrid system and is instrumental in studying complex nonlinear phenomena arising in the impulsive Goodwin oscillator. A simulation example is presented to demonstrate the utility of the proposed approach in bifurcation analysis.

  • 72. Churilov, Alexander N.
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Zhusubaliyev, Zhanybai T.
    Impulsive Goodwin oscillator with large delay: Periodic oscillations, bistability, and attractors2016Inngår i: Nonlinear Analysis: Hybrid Systems, ISSN 1751-570X, E-ISSN 1878-7460, Vol. 21, s. 171-183Artikkel i tidsskrift (Fagfellevurdert)
  • 73.
    Cubo, Ruben
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Jltsova, Elena
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Neurokirurgi.
    Andersson, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Calculating Directional Deep Brain Stimulation Settings by Constrained OptimizationArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: Deep Brain Stimulation (DBS) consists of delivering electrical stimuli to a brain target via an implanted lead to treat neurodegenerative conditions. Individualized stimulation is vital to ensure therapeutic results, since DBS may otherwise become ineffective or cause undesirable side effects. Since the DBS pulse generator is battery-driven, power consumption incurred by the stimulation is important. In this study, target coverage and power consumption are compared over a patient population for clinical and model-based patient-specific settings calculated by constrained optimization. Methods: Brain models for five patients undergoing bilateral DBS were built. Mathematical optimization of activated tissue volume was utilized to calculate stimuli amplitudes, with and without specifying the volumes, where stimulation was not allowed to avoid side effects. Power consumption was estimated using measured impedance values and battery life under both clinical and optimized settings. Results: It was observed that clinical settings are generally less aggressive than the ones suggested by unconstrained model-based optimization, especially under asymmetrical stimulation. The DBS settings satisfying the constraints were close to the clinical values. Conclusion: The use of mathematical models to suggest optimal patient-specific DBS settings that observe technological and safety constraints can save time in clinical practice. It appears though that the considered anatomy-related safety constraints depend on the patient and further research is needed in this regard. Power consumption is important to consider since it increases with the square of the stimuli amplitude and critically affects battery life. Significance: This work highlights the need of specifying the brain volumes to be avoided by stimulation while optimizing the DBS amplitude, in contrast to minimizing general stimuli overspill, and applies the technique to a cohort of patients. It also stresses the importance of taking power consumption into account.

  • 74.
    Cubo, Ruben
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Online tissue conductivity estimation in Deep Brain StimulationInngår i: Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established therapy that consists of sending electrical pulses to the brain via a chronically implanted electrode. DBS is used to alleviate symptoms of neurological medical conditions such as Parkinson’s Disease and Essential Tremor. However, the stimulation effect is patient-specific and hard to predict. In addition, the brain tissue around the lead changes its electrical properties over time thus influencing the therapeutical effect. This paper proposes an approach to online conductivity estimation by sending a specially designed electrical probing signal into the brain from one contact of the electrode and measuring the response on another one. A conductivity estimate is then obtained from the parameters of an estimated linear time-invariant model. Both voltage-controlled and current-controlled DBS systems are treated. Continuous Least Squares and Laguerre domain identification are employed to estimate the involved models. Results suggest that a smooth Gaussian-shaped signal is sufficient to identify the model in a noise-free situation, but the resulting excitation might be not enough for accurate estimation in the face of disturbances, e.g. local field potential due to neuron firings. Better excitation is produced by input signals with designed Laguerre spectra. Due to the infeasibility of assigning electrical properties to the surroundings of the lead in vivo, synthetic data from an individualized high-fidelity mathematical model of DBS are used instead. The latter model is validated against clinically measured impedance values.

  • 75.
    Cubo, Rubén
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Mathematical modeling for optimization of Deep Brain Stimulation2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Deep Brain Stimulation (DBS) consists of sending mild electric stimuli to the brain via a chronically implanted lead. The therapy is used to alleviate the symptoms of different neurological diseases, such as Parkinson's Disease. However, its underlying biological mechanism is currently unknown. DBS patients undergo a lengthy trial-and-error procedure in order to tune the stimuli so that the treatment achieves maximal therapeutic benefits while limiting side effects that are often present with large stimulation values.

    The present licentiate thesis deals with mathematical modeling for DBS, extending it towards optimization. Mathematical modeling is motivated by the difficulty of obtaining in vivo measurements from the brain, especially in humans. It is expected to facilitate the optimization of the stimuli delivered to the brain and be instrumental in evaluating the performance of novel lead designs. Both topics are discussed in this thesis.

    First, an analysis of numerical accuracy is presented in order to verify the DBS models utilized in this study. Then a performance comparison between a state-of-the-art lead and a novel field-steering lead using clinical settings is provided. Afterwards, optimization schemes using intersection of volumes and electric field control are described, together with some simplification tools, in order to speed up the computations involved in the modeling.

    Delarbeid
    1. Accuracy of the Finite Element Method in Deep Brain Stimulation Modelling
    Åpne denne publikasjonen i ny fane eller vindu >>Accuracy of the Finite Element Method in Deep Brain Stimulation Modelling
    2014 (engelsk)Inngår i: Proc. International Conference on Control Applications: CCA 2014, Piscataway, NJ: IEEE , 2014, s. 1479-1484Konferansepaper, Publicerat paper (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    Piscataway, NJ: IEEE, 2014
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-238211 (URN)10.1109/CCA.2014.6981533 (DOI)000366055800214 ()978-1-4799-7409-2 (ISBN)
    Konferanse
    CCA 2014, October 8–10, Antibes, France
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2014-10-10 Laget: 2014-12-10 Sist oppdatert: 2018-03-29bibliografisk kontrollert
    2. Target coverage and selectivity in field steering brain stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Target coverage and selectivity in field steering brain stimulation
    2014 (engelsk)Inngår i: Proc. 36th International Conference of the IEEE Engineering in Medicine and Biology Society, Piscataway, NJ: IEEE , 2014, s. 522-525Konferansepaper, Publicerat paper (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    Piscataway, NJ: IEEE, 2014
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-252475 (URN)10.1109/EMBC.2014.6943643 (DOI)000350044700130 ()978-1-4244-7929-0 (ISBN)
    Konferanse
    EMBC 2014, August 26–30, Chicago, IL
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2014-08-30 Laget: 2015-05-07 Sist oppdatert: 2016-04-16bibliografisk kontrollert
    3. Model-based optimization of lead configurations in Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Model-based optimization of lead configurations in Deep Brain Stimulation
    2015 (engelsk)Inngår i: Proc. 1st International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, International Academy, Research and Industry Association (IARIA), 2015, s. 14-19Konferansepaper, Publicerat paper (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    International Academy, Research and Industry Association (IARIA), 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-238214 (URN)978-1-61208-446-6 (ISBN)
    Konferanse
    SPWID 2015, June 21–26, Brussels, Belgium
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2015-06-26 Laget: 2014-12-10 Sist oppdatert: 2016-04-17bibliografisk kontrollert
    4. Electric field modeling and spatial control in Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Electric field modeling and spatial control in Deep Brain Stimulation
    2015 (engelsk)Inngår i: Proc. 54th Conference on Decision and Control, Piscataway, NJ: IEEE , 2015, s. 3846-3851Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established treatment, in e.g. Parkinson's Disease, whose underlying biological mechanisms are unknown. In DBS, electrical stimulation is delivered through electrodes surgically implanted into certain regions of the brain of the patient. Mathematical models aiming at a better understanding of DBS and optimization of its therapeutical effect through the simulation of the electrical field propagating in the brain tissue have been developed in the past decade. The contribution of the present study is twofold: First, an analytical approximation of the electric field produced by an emitting contact is suggested and compared to the numerical solution given by a Finite Element Method (FEM) solver. Second, the optimal stimulation settings are evaluated by fitting the field distribution to a target one to control the spread of the stimulation. Optimization results are compared to those of a geometric approach, maximizing the intersection between the target and the activated volume in the brain tissue and reducing the stimulated area beyond said target. Both methods exhibit similar performance with respect to the optimal stimuli, with the electric field control approach being faster and more versatile.

    sted, utgiver, år, opplag, sider
    Piscataway, NJ: IEEE, 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-284317 (URN)10.1109/CDC.2015.7402817 (DOI)000381554504006 ()9781479978847 (ISBN)
    Konferanse
    CDC 2015, December 15–18, Osaka, Japan
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2015-12-18 Laget: 2016-04-16 Sist oppdatert: 2018-03-29bibliografisk kontrollert
  • 76.
    Cubo, Rubén
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Model-based optimization for individualized deep brain stimulation2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established therapy that is predominantly  utilized in treating the symptoms of neurodegenerative diseases such as Parkinson's Disease and Essential Tremor, crippling diseases like Chronic Pain and Epilepsy, and psychiatric diseases such as Schizophrenia and Depression. Due to its invasive nature, DBS is considered as a last resort therapy.DBS is performed by transmitting electric pulses through an electrode implanted in the brain of the patient.

    The stimulation is driven by a battery-powered Implanted Pulse Generator. The brain is a very delicate and complex organ and, therefore, accurate positioning the electrode is vital. To achieve a satisfactory therapeutical result, the stimulation targets a certain predefined brain structure that depends on the disease.

    The effect of DBS depends on the individual, the chosen stimulating contact(s), and the pulse parameters, i.e. amplitude, frequency, width, and shape. Tuning these parameters to the best effect is currently done by a lengthy trial-and-error process. Insufficient stimulation does not properly alleviate the symptoms of the disease, while overstimulation or stimulation off target is prone to side effects.

    This work envisions assisting physicians in DBS therapy by utilizing model-based estimation and optimization, maximizing stimulation of the target and minimizing stimulation in potentially problematic areas of the brain. This work focuses on amplitude and contact selection. Because of inter-patient differences, individualized models based on clinical imaging have to be created. Alternatively, semi-individualized models can be designed using atlases that save time but potentially introduce inaccuracies. Other optimization  applications to DBS are proposed in the thesis, e.g. fault alleviation and electrode design.

    Electrical properties of the brain can change over time and alter the stimulation spread. A system identification approach has been proposed to quantify these changes.

    The main aim of DBS is to alleviate the symptoms of the disease and quantifying symptoms is important. The ultimate vision of this work is to design a closed-loop system that can deliver optimal stimulation to the brain while automatically adapting to changes in the brain and the severity of symptoms.

    Delarbeid
    1. Accuracy of the Finite Element Method in Deep Brain Stimulation Modelling
    Åpne denne publikasjonen i ny fane eller vindu >>Accuracy of the Finite Element Method in Deep Brain Stimulation Modelling
    2014 (engelsk)Inngår i: Proc. International Conference on Control Applications: CCA 2014, Piscataway, NJ: IEEE , 2014, s. 1479-1484Konferansepaper, Publicerat paper (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    Piscataway, NJ: IEEE, 2014
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-238211 (URN)10.1109/CCA.2014.6981533 (DOI)000366055800214 ()978-1-4799-7409-2 (ISBN)
    Konferanse
    CCA 2014, October 8–10, Antibes, France
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2014-10-10 Laget: 2014-12-10 Sist oppdatert: 2018-03-29bibliografisk kontrollert
    2. Optimization of lead design and electrode configuration in Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Optimization of lead design and electrode configuration in Deep Brain Stimulation
    2016 (engelsk)Inngår i: International Journal On Advances in Life Sciences, ISSN 1942-2660, E-ISSN 1942-2660, Vol. 8, s. 76-86Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-305224 (URN)
    Tilgjengelig fra: 2016-06-30 Laget: 2016-10-13 Sist oppdatert: 2018-03-29bibliografisk kontrollert
    3. Electric field modeling and spatial control in Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Electric field modeling and spatial control in Deep Brain Stimulation
    2015 (engelsk)Inngår i: Proc. 54th Conference on Decision and Control, Piscataway, NJ: IEEE , 2015, s. 3846-3851Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established treatment, in e.g. Parkinson's Disease, whose underlying biological mechanisms are unknown. In DBS, electrical stimulation is delivered through electrodes surgically implanted into certain regions of the brain of the patient. Mathematical models aiming at a better understanding of DBS and optimization of its therapeutical effect through the simulation of the electrical field propagating in the brain tissue have been developed in the past decade. The contribution of the present study is twofold: First, an analytical approximation of the electric field produced by an emitting contact is suggested and compared to the numerical solution given by a Finite Element Method (FEM) solver. Second, the optimal stimulation settings are evaluated by fitting the field distribution to a target one to control the spread of the stimulation. Optimization results are compared to those of a geometric approach, maximizing the intersection between the target and the activated volume in the brain tissue and reducing the stimulated area beyond said target. Both methods exhibit similar performance with respect to the optimal stimuli, with the electric field control approach being faster and more versatile.

    sted, utgiver, år, opplag, sider
    Piscataway, NJ: IEEE, 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-284317 (URN)10.1109/CDC.2015.7402817 (DOI)000381554504006 ()9781479978847 (ISBN)
    Konferanse
    CDC 2015, December 15–18, Osaka, Japan
    Forskningsfinansiär
    EU, European Research Council, 247035
    Tilgjengelig fra: 2015-12-18 Laget: 2016-04-16 Sist oppdatert: 2018-03-29bibliografisk kontrollert
    4. Optimization-based contact fault alleviation in deep brain stimulation leads
    Åpne denne publikasjonen i ny fane eller vindu >>Optimization-based contact fault alleviation in deep brain stimulation leads
    2018 (engelsk)Inngår i: IEEE transactions on neural systems and rehabilitation engineering, ISSN 1534-4320, E-ISSN 1558-0210, Vol. 26, nr 1, s. 69-76Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-342456 (URN)10.1109/TNSRE.2017.2769707 (DOI)000422939000008 ()29324404 (PubMedID)
    Tilgjengelig fra: 2017-11-03 Laget: 2018-02-26 Sist oppdatert: 2018-03-29bibliografisk kontrollert
    5. Semi-Individualized electrical models in deep brain stimulation: A variability analysis
    Åpne denne publikasjonen i ny fane eller vindu >>Semi-Individualized electrical models in deep brain stimulation: A variability analysis
    Vise andre…
    2017 (engelsk)Inngår i: 2017 IEEE Conference on Control Technology and Applications (CCTA), IEEE, 2017, s. 517-522Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is a well-established treatment in neurodegenerative diseases, e.g. Parkinson's Disease. It consists of delivering electrical stimuli to a target in the brain via a chronically implanted lead. To expedite the tuning of DBS stimuli to best therapeutical effect, mathematical models have been developed during recent years. The electric field produced by the stimuli in the brain for a given lead position is evaluated by numerically solving a Partial Differential Equation with the medium conductivity as a parameter. The latter is patient- and target-specific but difficult to measure in vivo. Estimating brain tissue conductivity through medical imaging is feasible but time consuming due to registration, segmentation and post-processing. On the other hand, brain atlases are readily available and processed. This study analyzes how alternations in the conductivity due to inter-patient variability or lead position uncertainties affect both the stimulation shape and the activation of a given target. Results suggest that stimulation shapes are similar, with a Dice's Coefficient between 93.2 and 98.8%, with a higher similarity at lower depths. On the other hand, activation shows a significant variation of 17 percentage points, with most of it being at deeper positions as well. It is concluded that, as long as the lead is not too deep, atlases can be used for conductivity maps with acceptable accuracy instead of fully individualized though medical imaging models.

    sted, utgiver, år, opplag, sider
    IEEE, 2017
    Emneord
    bioelectric phenomena, biological tissues, biomedical electrodes, brain, diseases, neurophysiology, partial differential equations, patient treatment, DBS stimuli, Parkinson disease, Partial Differential Equation, brain atlases, brain tissue conductivity, chronically implanted lead, deep brain stimulation, electric field, electrical stimuli, interpatient variability, medical imaging models, neurodegenerative diseases, semiIndividualized electrical models, variability analysis, Brain modeling, Computational modeling, Conductivity, Lead, Mathematical model, Satellite broadcasting
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-347344 (URN)10.1109/CCTA.2017.8062514 (DOI)000426981500084 ()978-1-5090-2183-3 (ISBN)978-1-5090-2182-6 (ISBN)978-1-5090-2181-9 (ISBN)
    Konferanse
    1st Annual IEEE Conference on Control Technology and Applications, 27-30 Aug. 2017, Mauna Lani, HI, USA.
    Tilgjengelig fra: 2018-03-29 Laget: 2018-03-29 Sist oppdatert: 2018-08-17bibliografisk kontrollert
    6. Calculating Directional Deep Brain Stimulation Settings by Constrained Optimization
    Åpne denne publikasjonen i ny fane eller vindu >>Calculating Directional Deep Brain Stimulation Settings by Constrained Optimization
    Vise andre…
    (engelsk)Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Abstract [en]

    Objective: Deep Brain Stimulation (DBS) consists of delivering electrical stimuli to a brain target via an implanted lead to treat neurodegenerative conditions. Individualized stimulation is vital to ensure therapeutic results, since DBS may otherwise become ineffective or cause undesirable side effects. Since the DBS pulse generator is battery-driven, power consumption incurred by the stimulation is important. In this study, target coverage and power consumption are compared over a patient population for clinical and model-based patient-specific settings calculated by constrained optimization. Methods: Brain models for five patients undergoing bilateral DBS were built. Mathematical optimization of activated tissue volume was utilized to calculate stimuli amplitudes, with and without specifying the volumes, where stimulation was not allowed to avoid side effects. Power consumption was estimated using measured impedance values and battery life under both clinical and optimized settings. Results: It was observed that clinical settings are generally less aggressive than the ones suggested by unconstrained model-based optimization, especially under asymmetrical stimulation. The DBS settings satisfying the constraints were close to the clinical values. Conclusion: The use of mathematical models to suggest optimal patient-specific DBS settings that observe technological and safety constraints can save time in clinical practice. It appears though that the considered anatomy-related safety constraints depend on the patient and further research is needed in this regard. Power consumption is important to consider since it increases with the square of the stimuli amplitude and critically affects battery life. Significance: This work highlights the need of specifying the brain volumes to be avoided by stimulation while optimizing the DBS amplitude, in contrast to minimizing general stimuli overspill, and applies the technique to a cohort of patients. It also stresses the importance of taking power consumption into account.

    Emneord
    Neuromodulation, Deep Brain Stimulation, inverse problems
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-347345 (URN)
    Tilgjengelig fra: 2018-03-29 Laget: 2018-03-29 Sist oppdatert: 2018-03-29
    7. Online tissue conductivity estimation in Deep Brain Stimulation
    Åpne denne publikasjonen i ny fane eller vindu >>Online tissue conductivity estimation in Deep Brain Stimulation
    (engelsk)Inngår i: Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established therapy that consists of sending electrical pulses to the brain via a chronically implanted electrode. DBS is used to alleviate symptoms of neurological medical conditions such as Parkinson’s Disease and Essential Tremor. However, the stimulation effect is patient-specific and hard to predict. In addition, the brain tissue around the lead changes its electrical properties over time thus influencing the therapeutical effect. This paper proposes an approach to online conductivity estimation by sending a specially designed electrical probing signal into the brain from one contact of the electrode and measuring the response on another one. A conductivity estimate is then obtained from the parameters of an estimated linear time-invariant model. Both voltage-controlled and current-controlled DBS systems are treated. Continuous Least Squares and Laguerre domain identification are employed to estimate the involved models. Results suggest that a smooth Gaussian-shaped signal is sufficient to identify the model in a noise-free situation, but the resulting excitation might be not enough for accurate estimation in the face of disturbances, e.g. local field potential due to neuron firings. Better excitation is produced by input signals with designed Laguerre spectra. Due to the infeasibility of assigning electrical properties to the surroundings of the lead in vivo, synthetic data from an individualized high-fidelity mathematical model of DBS are used instead. The latter model is validated against clinically measured impedance values.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-347346 (URN)
    Tilgjengelig fra: 2018-03-29 Laget: 2018-03-29 Sist oppdatert: 2018-03-29
  • 77.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Fahlström, Markus
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Radiologi.
    Jiltsova, Elena
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Neurologi.
    Andersson, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Calculating Deep Brain Stimulation Amplitudes and Power Consumption by Constrained Optimization2019Inngår i: Journal of Neural Engineering, ISSN 1741-2560, E-ISSN 1741-2552, Vol. 16, nr 1, artikkel-id 016020Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: Deep brain stimulation (DBS) consists of delivering electrical stimuli to a brain target via an implanted lead to treat neurological and psychiatric conditions. Individualized stimulation is vital to ensure therapeutic results, since DBS may otherwise become ineffective or cause undesirable side effects. Since the DBS pulse generator is battery-driven, power consumption incurred by the stimulation is important. In this study, target coverage and power consumption are compared over a patient population for clinical and model-based patient-specific settings calculated by constrained optimization.

    Approach: Brain models for five patients undergoing bilateral DBS were built. Mathematical optimization of activated tissue volume was utilized to calculate stimuli amplitudes, with and without specifying the volumes, where stimulation was not allowed to avoid side effects. Power consumption was estimated using measured impedance values and battery life under both clinical and optimized settings.

    Results: It was observed that clinical settings were generally less aggressive than the ones suggested by unconstrained model-based optimization, especially under asymmetrical stimulation. The DBS settings satisfying the constraints were close to the clinical values.

    Significance: The use of mathematical models to suggest optimal patient-specific DBS settings that observe technological and safety constraints can save time in clinical practice. It appears though that the considered safety constraints based on brain anatomy depend on the patient and further research into it is needed. This work highlights the need of specifying the brain volumes to be avoided by stimulation while optimizing the DBS amplitude, in contrast to minimizing general stimuli overspill, and applies the technique to a cohort of patients. It also stresses the importance of considering power consumption in DBS optimization, since it increases with the square of the stimuli amplitude and also critically affects battery life through pulse frequency and duty cycle.

  • 78.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Fahlström, Markus
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Radiologi. Uppsala Univ Hosp, Dept Biomed Technol Med Phys & IT, Uppsala, Sweden.
    Jiltsova, Elena
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Neurologi.
    Andersson, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Semi-Individualized electrical models in deep brain stimulation: A variability analysis2017Inngår i: 2017 IEEE Conference on Control Technology and Applications (CCTA), IEEE, 2017, s. 517-522Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is a well-established treatment in neurodegenerative diseases, e.g. Parkinson's Disease. It consists of delivering electrical stimuli to a target in the brain via a chronically implanted lead. To expedite the tuning of DBS stimuli to best therapeutical effect, mathematical models have been developed during recent years. The electric field produced by the stimuli in the brain for a given lead position is evaluated by numerically solving a Partial Differential Equation with the medium conductivity as a parameter. The latter is patient- and target-specific but difficult to measure in vivo. Estimating brain tissue conductivity through medical imaging is feasible but time consuming due to registration, segmentation and post-processing. On the other hand, brain atlases are readily available and processed. This study analyzes how alternations in the conductivity due to inter-patient variability or lead position uncertainties affect both the stimulation shape and the activation of a given target. Results suggest that stimulation shapes are similar, with a Dice's Coefficient between 93.2 and 98.8%, with a higher similarity at lower depths. On the other hand, activation shows a significant variation of 17 percentage points, with most of it being at deeper positions as well. It is concluded that, as long as the lead is not too deep, atlases can be used for conductivity maps with acceptable accuracy instead of fully individualized though medical imaging models.

  • 79.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Jiltsova, Elena
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Neurokirurgi.
    Fahlström, Markus
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Radiologi.
    Andersson, Helena
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Optimization of deep brain stimulation by means of a patient-specific mathematical model2016Konferansepaper (Fagfellevurdert)
  • 80.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Accuracy of the Finite Element Method in Deep Brain Stimulation Modelling2014Inngår i: Proc. International Conference on Control Applications: CCA 2014, Piscataway, NJ: IEEE , 2014, s. 1479-1484Konferansepaper (Fagfellevurdert)
  • 81.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Andersson, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Deep Brain Stimulation therapies: a control-engineering perspective2017Inngår i: Proc. American Control Conference: ACC 2017, IEEE, 2017, s. 104-109Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established therapy for treating e.g. Parkinson's disease, essential tremor, as well as epilepsy. In DBS, chronic pulsatile electrical stimulation is administered to a certain target area of the brain through a surgically implanted lead. The stimuli parameters have to be properly tuned in order to achieve therapeutical effect that in most cases is alleviation of motor symptoms. Tuning of DBS currently is a tedious task since it is performed manually by medical personnel in a trial-and-error manner. It can be dramatically improved and expedited by means of recently developed mathematical models together with control and estimation technology. This paper presents a control engineering perspective on DBS, viewing it as a control system for minimizing the severity of the symptoms through coordinated manipulation of the stimuli parameters. The DBS model structure comprises a stimuli model, an activation model, and a symptoms model. Each of those is individualized from patient data obtained through medical imaging, electrical measurements, and objective symptom quantification. The proposed approach is illustrated by simulation and clinical data from an individualized DBS model being developed by the authors.

  • 82.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Model-based optimization of individualized Deep Brain Stimulation therapy2016Inngår i: IEEE Design & Test, ISSN 2168-2356, Vol. 33, nr 4, s. 74-81Artikkel i tidsskrift (Fagfellevurdert)
  • 83.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Stimulation field coverage and target structure selectivity in field steering brain stimulation2014Konferansepaper (Fagfellevurdert)
  • 84.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Linkoping Univ, Dept Biomed Engn, S-58183 Linkoping, Sweden; Medtron Eindhoven Design Ctr, Medtron Neuromodulat, Eindhoven, Netherlands.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Electric field modeling and spatial control in Deep Brain Stimulation2015Inngår i: Proc. 54th Conference on Decision and Control, Piscataway, NJ: IEEE , 2015, s. 3846-3851Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Deep Brain Stimulation (DBS) is an established treatment, in e.g. Parkinson's Disease, whose underlying biological mechanisms are unknown. In DBS, electrical stimulation is delivered through electrodes surgically implanted into certain regions of the brain of the patient. Mathematical models aiming at a better understanding of DBS and optimization of its therapeutical effect through the simulation of the electrical field propagating in the brain tissue have been developed in the past decade. The contribution of the present study is twofold: First, an analytical approximation of the electric field produced by an emitting contact is suggested and compared to the numerical solution given by a Finite Element Method (FEM) solver. Second, the optimal stimulation settings are evaluated by fitting the field distribution to a target one to control the spread of the stimulation. Optimization results are compared to those of a geometric approach, maximizing the intersection between the target and the activated volume in the brain tissue and reducing the stimulated area beyond said target. Both methods exhibit similar performance with respect to the optimal stimuli, with the electric field control approach being faster and more versatile.

  • 85.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Model-based optimization of lead configurations in Deep Brain Stimulation2015Inngår i: Proc. 1st International Conference on Smart Portable, Wearable, Implantable and Disability-oriented Devices and Systems, International Academy, Research and Industry Association (IARIA), 2015, s. 14-19Konferansepaper (Fagfellevurdert)
  • 86.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Optimization of lead design and electrode configuration in Deep Brain Stimulation2016Inngår i: International Journal On Advances in Life Sciences, ISSN 1942-2660, E-ISSN 1942-2660, Vol. 8, s. 76-86Artikkel i tidsskrift (Fagfellevurdert)
  • 87.
    Cubo, Rubén
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Åström, Mattias
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Target coverage and selectivity in field steering brain stimulation2014Inngår i: Proc. 36th International Conference of the IEEE Engineering in Medicine and Biology Society, Piscataway, NJ: IEEE , 2014, s. 522-525Konferansepaper (Fagfellevurdert)
  • 88.
    Dahlborg, Elin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Frequency control: Pay for performance2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The frequency control in the Nordic grid is to a large extent delivered by hydropower plants. The hydropower plants deliver frequency control of varying quality, meaning that a remuneration method based on more than just the static gain of the power plant is called for. This thesis has examined how three remuneration methods based on the hydropower plant output and the grid frequency deviation affects the grid stability.

    Using frequency data, the remunerated work along with the bandwidth and phase-crossover frequency was plotted and compared for varying governor settings.

    The results show that all three remuneration methods examined need constructive technical specifications (for example based on the frequency response) to not decrease the grid stability. The first remuneration method, where the power plant is remunerated for being on the right side of the power set point value as the grid frequency deviates, gave incentives for increased bandwidth, but no particular incentives regarding the phase-crossover frequency. The second remuneration method, where the power plant is remunerated for how well it matches the output power from a plant with no dynamics using a proportional controller, gave incentives for moderately high bandwidth and phase-crossover frequency. The third remuneration method, which remunerates how well the plant power output matches the load disturbance that gave rise to the grid frequency deviation, needs to be investigated further, but the initial analysis show that it did neither give incentives for increased bandwidth nor phase-crossover frequency.

  • 89. Dahlin, Johan
    et al.
    Lindsten, Fredrik
    Schön, Thomas B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Particle Metropolis–Hastings using gradient and Hessian information2015Inngår i: Statistics and computing, ISSN 0960-3174, E-ISSN 1573-1375, Vol. 25, nr 1, s. 81-92Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Particle Metropolis–Hastings (PMH) allows for Bayesian parameter inference in nonlinear state space models by combining Markov chain Monte Carlo (MCMC) and particle filtering. The latter is used to estimate the intractable likelihood. In its original formulation, PMH makes use of a marginal MCMC proposal for the parameters, typically a Gaussian random walk. However, this can lead to a poor exploration of the parameter space and an inefficient use of the generated particles. We propose a number of alternative versions of PMH that incorporate gradient and Hessian information about the posterior into the proposal. This information is more or less obtained as a byproduct of the likelihood estimation. Indeed, we show how to estimate the required information using a fixed-lag particle smoother, with a computational cost growing linearly in the number of particles. We conclude that the proposed methods can: (i) decrease the length of the burn-in phase, (ii) increase the mixing of the Markov chain at the stationary phase, and (iii) make the proposal distribution scale invariant which simplifies tuning.

  • 90.
    Dahlin, Johan
    et al.
    Department of Computer and Information Science, Linköping University, Linköping, Sweden.
    Schön, Thomas B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Getting started with particle Metropolis-Hastings for inference in nonlinear dynamical models2019Inngår i: Journal of Statistical Software, ISSN 1548-7660, E-ISSN 1548-7660, Vol. 88, nr CN2, s. 1-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This tutorial provides a gentle introduction to the particle Metropolis-Hastings (PMH) algorithm for parameter inference in nonlinear state-space models together with a software implementation in the statistical programming language R. We employ a step-by-step approach to develop an implementation of the PMH algorithm (and the particle filter within) together with the reader. This final implementation is also available as the package pmhtutorial in the CRAN repository. Throughout the tutorial, we provide some intuition as to how the algorithm operates and discuss some solutions to problems that might occur in practice. To illustrate the use of PMH, we consider parameter inference in a linear Gaussian state-space model with synthetic data and a nonlinear stochastic volatility model with real-world data.

  • 91.
    Dahlqvist, Matilda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Sparsity Promoting Linear Quadratic Regulator for Heavy Duty Vehicle Platooning2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Heavy Duty Vehicle Platooning is seen as a possible way to reducefuel consumption, in part obtained by reducing the airdrag. Toapply this concept in reality there is need of a safe and fuelefficient way to automatically control the longitudinal velocity.But as with all applications there are restrictions of what isreally possible. This work focus on a few restrictions in the useof wireless communication, which is used to send information tothe controllers.

    This study determines a sparse optimal feedback gain matrixwithout loosing performance of the controller during HDVplatooning. It determines with what other vehicles and how thevehicles in the platoon need to communicate. It is a theoreticalstudy which is exploring the Linear Quadratic Sparsity PromotingRegulator (LQRSP) a method proposed by Fardad, Lin andJovanovic(2011b). The main interest was to find a controller thatis sparse structured and generated from a centralized controllerwith the same performance as the original controller. Anotherinterest was also to determine a pattern of dependencies ofinformation sent between vehicles, which should make it possibleto draw conclusions on needed communication links duringplatooning.

    A linearized vehicle model was derived from the forces acting on adriving vehicle and from the dynamics of the powertrain. Thisvehicle model is then used to derive a model for the whole platoonaccording to the states of interest. The performance of threedifferent controllers was analyzed, one decentralized controller,one Linear Quadratic Tracking Controller and the SparsityPromoting Linear Quadratic Regulator.

    The comparison between the controller performances shows that thecontroller with sparser structure on the feedback gain matrixkeeps the same performance as the controller used as reference.From the structure change of the feedback gain matrices a fewoverall conclusions can be made. For larger platoons theinformation regarding vehicles in front of the vehicle itself ismost desirable in combination with information about the states ofdistance change from the two following vehicles and velocitychange from the four following vehicles. The states representingthe integrated error between the reference signal and the firstvehicles velocity and the state which represents the distancechange between the first and second vehicle are states that areimportant for all vehicles in the platoon.

  • 92.
    Dai, Liang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Pelckmans, Kristiaan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    On the nuclear norm heuristic for a Hankel matrix completion problem2015Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 51, s. 268-272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This note addresses the question if and why the nuclear norm heuristic can recover an impulse response generated by a stable single-real-pole system, if elements of the upper-triangle of the associated Hankel matrix are given. Since the setting is deterministic, theories based on stochastic assumptions for low-rank matrix recovery do not apply in the considered situation. A 'certificate' which guarantees the success of the matrix completion task is constructed by exploring the structural information of the hidden matrix. Experimental results and discussions regarding the nuclear norm heuristic applied to a more general setting are also given.

  • 93.
    Dai, Liang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Pelckmans, Kristiaan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Bai, Er-Wei
    Identifiability and convergence analysis of the MINLIP estimator2015Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 51, s. 104-110Artikkel i tidsskrift (Fagfellevurdert)
  • 94.
    Dai, Liang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Schön, Thomas B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    A new structure exploiting derivation of recursive direct weight optimization2015Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 60, nr 6, s. 1683-1685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The recursive direct weight optimization method is used to solve challenging nonlinear system identification problems. This note provides a new derivation and a new interpretation of the method. The key underlying the note is to acknowledge and exploit a certain structure inherent in the problem.

  • 95. Decuyper, J.
    et al.
    De Troyer, T.
    Runacres, M. C.
    Tiels, Koen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Schoukens, J.
    On selecting appropriate training data to model an autonomous oscillator2018Inngår i: Proc. 28th International Conference on Noise and Vibration Engineering, Katholieke Univ. Leuven , 2018, s. 2601-2614Konferansepaper (Annet vitenskapelig)
  • 96.
    Diehl, Stefan
    et al.
    Centre for Mathematical Sciences, Lund University, P.O. Box 118, S-221 00 Lund, Sweden.
    Zambrano, Jesús
    School of Business, Society and Engineering, Mälardalen University, Box 883, SE-721 23 Västerås, Sweden.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Steady-state analyses of activated sludge processes with plug-flow reactor2017Inngår i: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 5, nr 1, s. 795-809Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Activated sludge processes (ASPs) consisting of a plug-flow reactor (PFR) and a settler are analyzed in steady-state operation using a reduced model consisting of one soluble substrate and one particulate biomass component modelling the dominating biological process. Monod biomass growth rate is assumed. Two settler models are studied. One is the commonly used ideal settler, or point settler, which is assumed to never be overloaded and to have unlimited flux capacity. The other recently published steady-state settler model includes hindered and compressive settling, and models a realistic limiting flux capacity. Generally, the steady-state concentration profiles within the PFR and the settler are governed by nonlinear ordinary differential equations. It is shown that the steady-state behaviour of the ASP can, however, be captured by equations without derivatives. New theoretical results are given, such as conditions by means of inequalities on input variables and parameters for a steady-state solution to exist. Another novel finding is that, if the incoming substrate concentration is increased from a low or moderate stationary value and the solids residence time is kept fixed, then this results in a lower effluent concentration in the new steady state. The steady-state equations are solved numerically for different operating conditions. For common parameter values, numerical solutions reveal that an ASP having a PFR, instead of a continuously stirred tank reactor, is far more efficient in reducing the effluent substrate concentration and this can be obtained for much lower recycle ratios, which reduces the pumping energy considerably.

  • 97. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Steady-state Analysis and Design of Activated Sludge Processes Including Compressive Settling2015Inngår i: Proc. 9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015Konferansepaper (Annet vitenskapelig)
  • 98. Diehl, Stefan
    et al.
    Zambrano, Jesús
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Steady-state analysis of activated sludge processes with a settler model including sludge compression2016Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 88, s. 104-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A reduced model of a completely stirred-tank bioreactor coupled to a settling tank with recycle is analyzed in its steady states. In the reactor, the concentrations of one dominant particulate biomass and one soluble substrate component are modelled. While the biomass decay rate is assumed to be constant, growth kinetics can depend on both substrate and biomass concentrations, and optionally model substrate inhibition. Compressive and hindered settling phenomena are included using the Bürger-Diehl settler model, which consists of a partial differential equation. Steady-state solutions of this partial differential equation are obtained from an ordinary differential equation, making steady-state analysis of the entire plant difficult. A key result showing that the ordinary differential equation can be replaced with an approximate algebraic equation simplifies model analysis. This algebraic equation takes the location of the sludge-blanket during normal operation into account, allowing for the limiting flux capacity caused by compressive settling to easily be included in the steady-state mass balance equations for the entire plant system. This novel approach grants the possibility of more realistic solutions than other previously published reduced models, comprised of yet simpler settler assumptions. The steady-state concentrations, solids residence time, and the wastage flow ratio are functions of the recycle ratio. Solutions are shown for various growth kinetics; with different values of biomass decay rate, influent volumetric flow, and substrate concentration.

  • 99.
    Ding, Kemi
    et al.
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Hong Kong, Hong Kong, Peoples R China.
    Li, Yuzhe
    Univ Alberta, Dept Elect & Comp Engn, Edmonton, AB, Canada.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Hong Kong, Hong Kong, Peoples R China.
    Multi-sensor Transmission Management for Remote State Estimation under Coordination2017Inngår i: IFAC-PapersOnLine, ISSN 1045-0823, E-ISSN 1797-318X, Vol. 50, nr 1, s. 3829-3834Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the remote state estimation in a cyber-physical system (CPS) using multiple sensors. The measurements of each sensor are transmitted to a remote estimator over a shared channel, where simultaneous transmissions from other sensors are regarded as interference signals. In such a competitive environment, each sensor needs to choose its transmission power for sending data packets taking into account of other sensors’ behavior. To model this interactive decision-making process among the sensors, we introduce a multi-player non-cooperative game framework. To overcome the inefficiency arising from the Nash equilibrium (NE) solution, we propose a correlation policy, along with the notion of correlation equilibrium (CE). An analytical comparison of the game value between the NE and the CE is provided, with/without the power expenditure constraints for each sensor. Also, numerical simulations demonstrate the comparison results.

  • 100.
    Ekman, M
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. DEPARTMENT OF SYSTEMS AND CONTROL.
    Samuelsson, P
    Carlsson, B.
    Control strategies in a JAVA based activated sludge process simulator2001Inngår i: 1st IWA Conference on ICA, Malmö, 2001, Vol. 1, s. 51-58Konferansepaper (Fagfellevurdert)
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