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- Eriksson, Karin, 1976, et al.
(author)
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Internal interconnections impact on control performance in a thermomechanical pulping process
- 2014
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In: 2009 10th European Control Conference, ECC 2009; Budapest; Hungary; 23 August 2009 through 26 August 2009. - : IEEE. ; , s. 3486-3491
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Conference paper (peer-reviewed)abstract
- Process integration may indeed be advantageous, particularly in a plant-wide economical sense, but there is also a potential risk that unnecessary difficulties are introduced when it comes to process control. This work identified several internal interconnections in a thermomechanical pulp refiner line as a result of an integration approach adopted during the process design. Firstly, a disturbance sensitivity analysis for the overall production process is carried out. Secondly, a simulation model is constructed and using real process data it is found to successfully reflect the complex dynamic behavior observed at the actual plant. The simulation model can provide indications on how the process performance can be improved by process design modifications. The results suggest that the presence of internal interconnections increases the demands on the control system and also set limits for its performance. If control aspects had been considered at the earliest stages of process development, the possibility to achieve satisfactory process performance could have been significantly improved.
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- Eriksson, Karin, 1976, et al.
(author)
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Internal interconnections impact on process operability
- 2005
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In: Proceedings of the International Mechanical Pulping Conference, 7-9 June 2005, Oslo, Norway. ; , s. 284-289
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Conference paper (peer-reviewed)abstract
- A model structure for a TMP production line, including allthe internal interconnections, has been derived. Simulationresults show that the model structure reflects thecharacteristics of the interconnected process and that thenature of the disturbance pattern arises from the fact that so many internal interconnections are present. The model candeliver insight into how modifications of the plant designwould affect the production performance. Besidesperformance, the internal interconnections also influence the process operability, which demonstrates the importance of considering control aspects at the process design stage.
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- Eriksson, Karin, 1976, et al.
(author)
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Refining zone temperature control: a good choice for pulp quality control?
- 2009
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In: 2009 International Mechanical Pulping Conference, IMPC 2009; Sundsvall; Sweden; 31 May 2009 through 4 June 2009. ; , s. 67-74
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Conference paper (peer-reviewed)abstract
- The results presented in this work show that it is not motivated to use the specific energy for controlling pulp quality in terms of CSF and MFL. This statement is based on the fact that it gives limited dynamic information of the refining process besides what already is given by the three traditional process variables, i.e. production rate, dilution water flow, and hydraulic pressure when predicting CSF and MFL by using ARMAX modeling procedures. Whereas, using the refining zone temperature measurements as inputs to the ARMAX models results in a significant improvement of the ability to predict these pulp quality variables. From a control perspective, this implies that refining zone temperature control is preferable to any concepts based on specific energy when it comes to minimization of pulp quality variations.
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- Eriksson, Leif, 1970, et al.
(author)
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Alignment of L-and C-Band SAR Images for Enhanced Observations of Sea Ice
- 2022
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In: International Geoscience and Remote Sensing Symposium (IGARSS). ; 2022-July, s. 3798-3801
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Conference paper (peer-reviewed)abstract
- This paper discusses the alignment of Synthetic Aperture Radar (SAR) image pairs with one image acquired at L-and the other at C-band. For our study we used data from ALOS-2 PALSAR-2 and Sentinel-1 taken over sea ice in the Fram Strait. The use of multifrequency SAR data is beneficial for sea ice characterization and classification because it combines the advantages of the frequency dependence of signal penetration depths and backscattering characteristics due to small-scale ice properties. For drifting sea ice, however, an immediate combination of image pairs acquired with a time gap is usually not possible. Such cases require to consider the effects of ice drift. In this study we investigate the possibility to compensate for sea ice drift for separation in acquisition time ranging from a few hours to several days. The first results are promising and suggest that alignment of SAR image pairs obtained at different frequencies is possible even for larger time gaps between acquisitions if drift and deformation can be estimated reliably.
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- Karlsson, Sebastian, 1994, et al.
(author)
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CCS in the pulp and paper industry - implications on regional biomass supply
- 2021
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In: 15th Greenhouse Gas Control Technologies Conference 2021, GHGT 2021.
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Conference paper (peer-reviewed)abstract
- The Swedish climate policy framework requires national GHG emissions to reach net zero by 2045 and become negative thereafter. Bioenergy carbon capture and storage (BECCS) has been identified as a possible main contributor to reach these targets by providing negative emissions - both to offset residual emissions in “hard-to-abate” sectors and to achieve net negative emissions. The pulp and paper industry is the single largest consumer of biomass in Sweden with many large point sources of biogenic CO2 emissions which could potentially be captured. This work investigates the biomass supply required for large scale implementation of BECCS in the pulp and paper industry. Regional biomass supply possibilities are evaluated by choosing four pulp and paper mills located in different parts of Sweden. The results show that regional biomass supply can limit the possibilities for BECCS implementation in regions with high competition for biomass. In regions with low competition and high availability of biomass regional biomass supply can potentially assist CCS implementation on biogenic sources. It is concluded that for a densely populated and industrialized region with high use of logging residues in the heating sector, in this work represented by southern Sweden where two of the studied mills are located, the possibility to increase regional supply of logging residues to fuel the capture process while maintaining mill production output, is limited due to competition for the same assortment of biomass from the energy sector (combined heat and power in district heating systems).
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- Kylin, Carl, 1996, et al.
(author)
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Over-The-Air Identification of Coupled Nonlinear Distortion in a MIMO Radar
- 2022
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In: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. ; 2022-June, s. 121-125
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Conference paper (peer-reviewed)abstract
- Compensation for nonlinear distortion caused by power amplifiers being driven into compression is a field that has been extensively explored by a number of authors. More complex models describing the coupled nonlinear distortion that can occur in an active antenna array also exist. To identify these models most authors assume that the output of each power amplifier can be measured directly. For a system with many antennas over-the-air identification might be favorable. The problem of identifying a system describing the joint effects of coupled nonlinear distortion over-the-air has been solved by other authors assuming model or setup simplifications. To tackle the problem with a more accurate model, an algorithm for identifying parameters of a Volterra series model describing coupled non-linear distortion in a digital radar is explored and illustrated with simulated data.
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