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  • 1.
    Backlund, Hans-Olof
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Höglund, Hans
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Study of tangential forces and temperature profiles in commercial refiners2003In: 2003 International Mechanical Pulping Conference, 2003, p. 379-388Conference paper (Refereed)
  • 2.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Control of the Drying Section in a Paper Machine During a Web Break: Reglermöte 2004, Göteborg2004Conference paper (Other academic)
    Abstract [en]

    A new control strategy for steam pressure control in the drying cylinders during web breaks is presented. The development is performed using a new physical model implemented in Matlab Simulink. The goal of the control strategy is to obtain the same drying properties after the web break as before the break as fast as possible.

  • 3.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Dryer section control in paper machines during web2006In: 13th Nordic Process Control Workshop Köpenhamn 2006, 2006Conference paper (Other academic)
  • 4.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Dryer Section Control in Paper Machines During Web Breaks2004Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Web breaks in the dryer section of a paper machine cause loss of production and quality problems. After a web break, the steam pressure in the cylinders must be reduced to avoid overheating. The goal of this project is to determine optimal steam pressure trajectories during web breaks, so that the production is restarted with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The model describes the relations between the steam valve position, the steam pressure, the cylinder temperature, and the paper temperature. The model is based on partial differential equations that describe heat conductivity for the cylinder and the paper web, and mass balances of water and dry material in the paper. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions between the steam pressure and the cylinder temperature, and between a logic signal that is active during web breaks and the cylinder temperature, respectively. The transfer functions obtained were used to find the optimal steam pressure trajectory during web breaks. A new feed-forward strategy for steam pressure control during web breaks is presented. The strategy has been tested on a paper machine with good results. The strategy is built on feed-forward compensation and has been well received at the mill.

  • 5.
    Ekvall, Jenny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Steam Pressure Control During Web Breaks in the Paper Machine: Control Systems 2004, Quebec City, Canada2004Conference paper (Other academic)
    Abstract [en]

    A new control strategy for steam pressure control in the drying cylinders during web breaks is presented. The development is performed using a new physical model implemented in Simulink. The goal of the control strategy is that the cylinder temperatures are retained when the production is restarted after the web break.

  • 6.
    Ekvall, Jenny
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Hägglund, Tore
    Improved web break strategy using a new approach for steam pressure control in paper machines2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 10, p. 1151-1160Article in journal (Refereed)
    Abstract [en]

    This paper presents a new strategy for steam pressure control during web breaks in the paper machine. The aim was to restart paper production with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions which were used to find the optimal steam pressure trajectory during web breaks. The resulting strategy has been tested on a paper machine with good results and it has been well received at the mill.

  • 7.
    Friden, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    The hydrodynamics of the cerebrospinal fluid in man. Instrumentation, computer methods, investigation procedures and physiological modelling1994Doctoral thesis, monograph (Other scientific)
  • 8.
    Fridén, Hakan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Virtual Control Room (VCR) - NPI - Status October 20042004Report (Other (popular science, discussion, etc.))
  • 9.
    Fridén, Häkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Process modelling - a future part in an operator's guide: Automatiseringsdagarna 2004 in Storlien2004Conference paper (Other scientific)
  • 10.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Multivariate batch modelling of baker's yeast production: CAC96 - International Conference Chemometrivs in Analytical Chemistry, Tarragona1996Conference paper (Other scientific)
  • 11.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    On-line multivariate statistical process control for continuous and batch processes2000In: Proceedings of ACHEMA 2000, 2000Conference paper (Other scientific)
  • 12.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Process modelling - a future part in an operators guide.: The FlowMac Conference year 2004, Kolmården, June 15-162004Conference paper (Other scientific)
  • 13.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Process Modelling in Real time with Multivariate Models: ProcessTeknik 2004, Göteborg 5-7 oktober2004Conference paper (Other scientific)
  • 14.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Virtual Control Room (VCR) : NPI - Project Report Sep 20052005Book (Other scientific)
  • 15.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Virtuellt Kontrollrum (VKR) - NPI - Status mars 20042004Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Rapporten beskriver driftsättningen av VKR hos NPI. Den redogör för installerad hård- och mjukvara, samt vilka tillämpningar som är aktuella.

  • 16.
    Fridén, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Näslund, Henrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Stattin, Andreas
    Löfgren, Göran
    Online decision support and optimization for kraft paper production2006In: Control systems 2006 : Measurement and control: applications for the operator, Tampere, Finland, 6-8 June 2006, Helsinki: Kopio Niini - Painoporssi, , 2006, p. 313-Conference paper (Other scientific)
    Abstract [en]

    The MondiPackaging Dynäs pulp & paper mill in Sweden produces strong sack and kraft paper from chemical softwood pulp. Despite good quality a project was initiated by a need for less variability in paper quality, and less energy consumption. It was known that there is variability in incoming stock, and that the HC and LC refining strategies could be improved. The aim of the project is to reduce energy consumption by 10%, and to reduce quality variation by installing a new online fibre analyzer, PulpEye, and implementing modern modelling and control methodology. We have used multivariate subspace models in combination with optimization to create an OPC based interactive application for on-line operator support and optimization of kraft paper production. The application is now installed and is under evaluation. The specific refiner energy has so far been reduced with at least 25%. The decision support application is indicating even more reduction potential.

  • 17.
    Fridén, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Stattin, Andreas
    Löfgren, Göran
    Online operator decision support and optimization for sack paper production by PAT based process automation2008In: Third pan-European PAT conference: Oct 7-8, Gothenburg, Sweden, 2008Conference paper (Other academic)
  • 18.
    Fridén, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Tano, Kent
    Using PLS models with both controlled and uncontrolled X variables for "Waht if..." prediction2005In: The 9th Scandinavian Symposium on Chemometrics, Reykjavik, Iceland 2005-09-30, Ornsköldsvik: NPI , 2005, p. 6-Conference paper (Other scientific)
    Abstract [en]

    In real-time industrial process applications, there is often a need to predict the effects of adjustments before actually effectuated. Multivariate prediction models based on historical data works fine for predictions as long as the new X data have the correlation structure preserved. This paper shows that such can anyway be used for �What if �� decision support in presence of correlated X variables, whenever it is possible to create a help model that predicts the influence of the manipulated X variables on the rest of the X variables.

  • 19.
    Fridén, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Wikström, Conny
    Modellering ger kontroll över batchprocesser1999In: Kemisk Tidskrift - Kemivärlden, ISSN 1104-2788, no 5, p. 41-47Article in journal (Other academic)
  • 20.
    Fridén, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Wikström, Conny
    Multivariate process monitoring and forcasting by projection methods1994In: Proceedings of the Third IEEE Conference on Control Applications Glasgow, 24-26 aug 1994: Vol. 2, Piscataway: IEEE Control Systems Society , 1994, p. 1345-1346Conference paper (Refereed)
    Abstract [en]

    Immense amounts of data are collected into today's modern process monitoring systems. There are, however, few methods that have the capability to grasp the essentials in these, usually heavily correlated, data. The multivariate statistical techniques, principal components (PC) modelling and modelling by projection to latent structures (PLS) are two methods that have a great potential for process monitoring and forecasting in these situations

  • 21. Kattaneh, Nouna
    et al.
    Albano, C
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Data pre-processing, wavelets, and OSC2000In: International Meeting on Chemical Engineering, Environmental Protection and Biotechnology. ACHEMA 2000, Frankfurt am Main, 22. – 27. 5. 2000, 2000Conference paper (Other scientific)
  • 22. Kettaneh, Nouna
    et al.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Lindgren, Å
    Multivariate modelling of batch processes2003In: Proceedings. 8th Scandinavian symposium on chemometrics Mariehamn, Sweden, 14–18 June 2003, 2003Conference paper (Other academic)
  • 23.
    Li, Jun
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Improving PID control based on Neural Network2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    PID is a prevalent tool of automatic control in both industry and home environment, and PID parameters are often forced to modify because of systematic service on the machines or systems, which is time-costing. The project aims to investigate the possibility of applying neural network and reducing PID configuration in controlling industry process, by means of establishing control models and comparing control performance between conventional PID method and improved PID control based on neural network where two built neural networks are considered as cores to adjust weights which result in the suggested PID parameters. Adaptive learning rate is also applied which is adjusted by the algorithm based on the error changes. Algorithm program is written in Siemens TIA Portal and simulated in Factory I/O. In general, the simulations after analysis have shown that the proposed model has a better performance than conventional PID in terms of steady state, deviations and consistency of control value except tuning time. In the future the author is dedicated to continue improving the mentioned model through quickening learning process, applying better activation function and modifying variable structure and so on.

  • 24.
    Nilsson, Hans-Erik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Sidén, Johan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Koptyug, Andrey
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Sensoranordning med RFID-enheter2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a sensor arrangement (100) suitable for determining a condition, for example moisture, comprising a first RFID-unit 5 (110) and a second RFID-unit (120) being subjected to said condition. The sensor arrangement is characterized in that the second RFID-unit (120) is at least partly provided with a degradation means (130) having such properties that, when subjected to said condition, the second RFID-unit (120) is functionally degraded to a greater extent than the first RFID-unit (110). The 10 invention also relates to a sensor arrangement product (199) comprising at least one sensor arrangement.

  • 25.
    Patrik, Jonsson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Road status sensors: A comparison of active and passive sensors2009In: TS116: Weather monitoring, 2009Conference paper (Refereed)
    Abstract [en]

    Knowledge of the road status and specifically knowledge of the freezing point of the road surface fluid is crucial in order to perform effective and environmentally safe road maintenance. Road status sensors installed in the road can be passive conductivity sensors or active freezing point sensors. In this paper the output from a passive and an active sensor has been studied when the sensors has been contaminated with common chemicals that can be present on the road surface such as oil, alcohol and glycol. The results indicated that only intelligent active sensors reliably can detect freezing points on the road surface.

  • 26.
    Westman, Tomas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Technology and Management, Mechanical Engineering and Mathematics.
    Utredning av AGV-reglering med differentialstyrd drivenhet2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
  • 27. Wikström, Conny
    et al.
    Albano, Christer
    Eriksson, Lennart
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Johansson, Erik
    Nordahl, Åke
    Rännar, Stefan
    Sandberg, Maria
    Kettaneh-Wold, Nouna
    Wold, Svante
    Multivariate process and quality monitoring applied to an electrolysis process.: Part II - Multivariate time-series analysis of lagged latent variables1998In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, Vol. 42, no 1-2, p. 233-240Article in journal (Refereed)
    Abstract [en]

    Multivariate time series analysis is applied to understand and model the dynamics of an electrolytic process manufacturing copper. Here, eight metal impurities were measured, twice daily, over a period of one year, to characterize the quality of the copper. In the data analysis, these eight variables were summarized by means of principal component analysis PCA.. Two principal component PC.scores were sufficient to well summarize the eight measured variables R2s0.67.. Subse-quently, the dynamics of these PC-scores latent variables.were investigated using multivariate time series analysis, i.e., par-tial least squares PLS.modelling of the lagged latent variables. Stochastic models of the auto-regressive moving average ARMA.family were appropriate for both PC-scores. Hence, the dynamics of both scores make the exponentially weighted moving average EWMA.control chart suitable for process monitoring.

  • 28. Wold, S.
    et al.
    Albano, C.
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Adaptive, robust, and non-linear PCA and PLS methods for on-line applications2000In: Proceedings of ACHEMA 2000, 2000Conference paper (Other scientific)
  • 29. Wold, Svante
    et al.
    Kettane, Nouna
    Fridén, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    Holmberg, Andrea
    Modelling and diagnostics of batch processes and analogous kinetic experiments. 1998In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, Vol. 44, no 1/2, p. 331-340Article in journal (Refereed)
    Abstract [en]

    In chemical kinetics and batch processes K variables are measured on the batches at regular time intervals. This gives a J×K matrix for each batch (J time points times K variables). Consequently, a set of N normal batches gives a three-way matrix of dimension (N×J×K). The case when batches have different length is also discussed. In a typical industrial application of batch modelling, the purpose is to diagnose an evolving batch as normal or not, and to obtain indications of variables that together behave abnormally in batch process upsets. Other applications giving the same form of data include pharmaco-kinetics, clinical and pharmacological trials where patients (or mice) are followed over time, material stability testing and other kinetic investigations. A new approach to the multivariate modelling of three-way kinetic and batch process data is presented. This approach is based on an initial PLS analysis of the ((N×J)×K) unfolded matrix ((batch×time)×variables) with ‘local time' used as a single y-variable. This is followed by a simple statistical analysis of the resulting scores and results in multivariate control charts suitable for monitoring the kinetics of new experiments or batches. ‘Upsets' are effectively diagnosed in these charts, and variables contributing to the upsets are indicated in contribution plots. In addition, the degree of ‘maturity' of the batch can be as predicted vs. observed local time. The analysis of batch data with respect to various questions is discussed with respect to typical objectives, overview and summary, classification, and quantitative modelling. This is illustrated by an industrial example of yeast production.

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