| 1. |
- Fiskari, Juha, et al.
(författare)
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Deep Eutectic Solvent Treatment to Low-Energy TMP to Produce Fibers for Papermaking
- 2018
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Ingår i: IMPC 2018. - Trondheim, Norway.
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Konferensbidrag (refereegranskat)abstract
- The aim of this research was to gain a better understanding on whether a novel process based on low-energy thermo-mechanical pulp (TMP) process followed by a chemical treatment with deep eutectic solvents (DESs) could produce fibers suitable for papermaking. In full scale production, these fibers could be produced at a much lower capital and operational costs, especially when utilizing existing TMP plants which are under the threat to be shut down or have already been shut down due to a decreasing demand for newsprint and other wood-containing papers.The efficiency of several DES treatments under various temperatures and times were evaluated by carrying out experiments in standard Teflon-lined autoclaves. A few tests were also performed in a unique nonstandard flow extractor. Pulp samples were characterized for their cellulose, hemicellulose and lignin contents. Moreover, tensile index was measured both before and after pulp refining. Depending on the solvent, the response of mechanical pulp varied, especially in terms of hemicellulose dissolution. Lactic acid, oxalic acid and urea, all in combination with choline chloride ([Ch]Cl) as the hydrogen bond acceptor, dissolved about 50% of the lignin of the low-energy TMP fibers under the tested conditions. The mixture of malic acid and [Ch]Cl was less effective in lignin dissolution. The mixture of urea and [Ch]Cl exhibited only a minor loss in hemicellulose content, when compared to the other tested DESs. Although 50% of the lignin was dissolved with minor loss in hemicellulose no improvement in tensile strength was observed, as it was rather the opposite. Another benefit with the mixture of urea and [Ch]Cl was that this DES did not appear to be corrosive to stainless steel. All other tested DESs—which were also quite acidic—were observed to be corrosive. Moreover, this DES-related corrosion was found to intensify at elevated temperatures.When chips were used as starting material with otherwise the same conditions almost no lignin was dissolved. This suggests that low-energy mechanical pulp is likely to be a good starting material for extracting lignin using DESs.
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| 2. |
- Flodén, Liselott, 1967-, et al.
(författare)
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A myriad shades of green
- 2009
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Ingår i: Proceedings of Bridges 2009, Banff, Alberta, Canada.
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Konferensbidrag (refereegranskat)abstract
- We discuss the possible application of techniques inspired by the theories of G-convergence and homogenization to understand mixtures of colors and how they appear as observed by the human eye. The ideas are illustrated by pictures describing the equivalent of a convergence process for different kinds of mixtures of colors.
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| 3. |
- Flodén, Liselott, et al.
(författare)
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Homogenization of a Hyperbolic-Parabolic Problem with Three Spatial Scales
- 2017
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Ingår i: Progress in Industrial Mathematics at ECMI 2016. - Cham : Springer. - 9783319630816 ; , s. 617-623
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Konferensbidrag (refereegranskat)abstract
- We study the homogenization of a certain linear hyperbolic-parabolic problem exhibiting two rapid spatial scales {ε; ε2}. The homogenization is performed by means of evolution multiscale convergence, a generalization of the concept of two-scale convergence to include any number of scales in both space and time. In particular we apply a compactness result for gradients. The outcome of the homogenization procedure is that we obtain a homogenized problem of hyperbolic-parabolic type together with two elliptic local problems, one for each rapid scale, for the correctors.
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| 4. |
- Flodén, Liselott, 1967-, et al.
(författare)
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On the determination of effective properties of certain structures with non-periodic temporal oscillations
- 2009
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Ingår i: MATHMOD 2009 - 6th Vienna International Conference on Mathematical Modelling. - Wien : Vienna University Press (WUV). - 9783901608353 ; , s. 2627-2630
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Konferensbidrag (refereegranskat)abstract
- We investigate the homogenization of an evolution problem modelled by a parabolic equation, where the coefficient describing the structure is periodic in space but may vary in time in a non-periodic way. This is performed applying a generalization of two-scale convergence called λ-scale convergence. We give a result on the characterization of the λ-scale limit of gradients under certain boundedness assumptions. This is then applied to perform the homogenization procedure. It turns out that, under a certain condition on the rate of change of the temporal variations, the effective property of the given structure can be determined the same way as in periodic cases.
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| 5. |
- Tourancheau, Sylvain, 1982-, et al.
(författare)
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Evaluation of quality of experience in interactive 3D visualization: methodology and results
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 9780819489357 ; , s. Art. no. 82880O-
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Konferensbidrag (refereegranskat)abstract
- Human factors are of high importance in 3D visualization, but subjective evaluation of 3D displays is not easy because of a high variability among users. This study aimed to evaluate and compare two different 3D visualization systems (a market stereoscopic display, and a state-of-the-art multi-view display) in terms of task performance and quality of experience (QoE), in the context of interactive visualization. An adapted methodology has been designed in order to focus on 3D differences and to reduce the influence of all other factors. 36 subjects took part in an experiment during which they were asked to solve different tasks in a synthetic 3D scene. After the experiment, they were asked to judge the quality of their experience, according to specific features. Results showed that scene understanding and precision was significantly better on the multi-view display. Concerning the quality of experience, visual comfort was judged significantly better on the multi-view display and visual fatigue was reported by 52% of the subjects on the stereoscopic display. This study has permitted to identify some factors influencing QoE such as prior experience and stereopsis threshold.
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| 6. |
- Tourancheau, Sylvain, 1982-, et al.
(författare)
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Subjective evaluation of user experience in interactive 3D-visualization in a medical context
- 2012
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Ingår i: Proceedings of the SPIE, vol 8318: Conference on Image Perception, Observer Performance, and Technology Assessment, San Diego, CA, USA, 4 - 9 February 2012. - : SPIE - International Society for Optical Engineering. ; , s. Art. no. 831814-
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Konferensbidrag (refereegranskat)abstract
- New display technologies enable the usage of 3D-visualization in a medical context. Even though user performance seems to be enhanced with respect to 2D thanks to the addition of recreated depth cues, human factors, and more particularly visual comfort and visual fatigue can still be a bridle to the widespread use of these systems. This study aimed at evaluating and comparing two different 3D visualization systems (a market stereoscopic display, and a state-of-the-art multi-view display) in terms of quality of experience (QoE), in the context of interactive medical visualization. An adapted methodology was designed in order to subjectively evaluate the experience of users. 14 medical doctors and 15 medical students took part in the experiment. After solving different tasks using the 3D reconstruction of a phantom object, they were asked to judge their quality of the experience, according to specific features. They were also asked to give their opinion about the influence of 3D-systems on their work conditions. Results suggest that medical doctors are opened to 3D-visualization techniques and are confident concerning their beneficial influence on their work. However, visual comfort and visual fatigue are still an issue of 3D-displays. Results obtained with the multi-view display suggest that the use of continuous horizontal parallax might be the future response to these current limitations.
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