| 1. |
- Walander, Magnus, 1991, et al.
(författare)
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Use of 3D-printed mixers in laboratory reactor design for modelling of heterogeneous catalytic converters
- 2021
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Ingår i: Chemical Engineering and Processing. - : Elsevier B.V.. - 0255-2701 .- 1873-3204. ; 164
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Tidskriftsartikel (refereegranskat)abstract
- A method for identifying radial concentration maldistribution in synthetic catalyst activity test (SCAT) benches, is presented, where spatially resolved concentration measurements are not available. The developed methodology was successfully tested for an injection-based SCAT. To resolve the radial concentration maldistribution a static mixer was designed, 3D-printed and inserted upstream the test sample. The methodology could also prove the effectiveness of the mixer, which did not only resolve the concentration maldistribution but also avoided causing reaction disturbances. The resulting increased axial dispersion from the turbulence created by the static mixer was evaluated using a 3D CFD model in Ansys Fluent 19. The axial dispersion of the injection-based SCAT bench was compared to a premixed SCAT bench through classical Aris-Taylor calculations. The results from the axial dispersion calculations show that the injection-based design with the use of a static mixer is far superior to the premixed design – both with regards to pulse broadening but also time delay. This is highly desirable for modelling studies towards zero emission exhaust aftertreatment. © 2021 The Authors
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| 2. |
- Sjöblom, Jonas, 1968, et al.
(författare)
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Modelling of non uniform washcoat in catalytic monolith reactors
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For advances in the design of exhaust aftertreatment systems, modelling can be a valuable tool. There have been various efforts in modelling the diesel oxidation catalyst (DOC) with varying degree of complexity. The simplest 1D models discretize the monolithic channel axially and use an effectiveness factor to account for different washcoat geometries. The more complex 1+1D models also resolve the catalyst washcoat which makes them able to better predict efficiency of e.g. layered catalysts. However, the vast majority of these 1+1D models assume the washcoat to be a uniform slab with homogeneous properties. Thus, they cannot identify tangential washcoat variations which have been found to have substantial effects on washcoat diffusivity (1). In this work a new parallel 1+1D reactor model has been developed. Similar to the sectionalizing method presented by Papadias et al (2), the washcoat is sliced into multiple tangential sections based on an evenly distributed angle. The model then solves each section of the washcoat independently – assuming that no mass is transferred between each section. Preliminary results (see figure 1) compare NO light-off simulations using the original 1+1D model and the parallel model using 3 sections. If the washcoat properties for each section are kept constant, then the conversion efficiency of the parallel model is slightly decreased because of the increased diffusive resistance of the thicker corners. However, if including the local porosity of each section (where the corners show a 13% increase in local porosity based on SEM images), the conversion efficiency of the parallel model is significantly higher because of the increased pore diffusivity in the corners. The proposed methodology enables analysis of local washcoat properties. The results are important for high performance modelling towards zero emission vehicles.
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| 3. |
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| 4. |
- Rönnberg, Niklas, 1973-, et al.
(författare)
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Sonifying the periphery: Supporting the formation of gestalt in air traffic control
- 2016
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Ingår i: Proceedings of ISon 2016, 5th Interactive Sonification Workshop, CITEC, Bielefeld University, Germany, December 16, 2016. - : CITEC, Bielefeld University. ; , s. 23-27
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Konferensbidrag (refereegranskat)abstract
- We report a design-led exploration of sonification to provide peripheral awareness in air traffic control centers. Our assumption is that by using musical sounds for sonification of peripheral events, it is possible to create a dynamic soundscape that complements the visual information to support the formation and maintenance of an airspace Gestalt throughout the air traffic controller’s interaction. An interactive sonification concept was designed, focusing on one controlled sector of airspace with inbound and outbound aircraft. A formative assessment of the sonification concept suggests that our approach might facilitate the air traffic controller’s work by providing complementary auditory information about inbound and outbound aircraft, particularly in situations where the traffic volume is moderate to low.
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| 5. |
- Tran Luciani, Danwei, 1985-, et al.
(författare)
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Designing fine-grained interactions for automation in air traffic control
- 2020
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Ingår i: Cognition, Technology & Work. - London : Springer London. - 1435-5558 .- 1435-5566. ; 22:4, s. 685-701
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Tidskriftsartikel (refereegranskat)abstract
- Our work aims to explore novel approaches to the challenge of designing the interaction between people and automation. Through a case study within the domain of air traffic control, we focus on designing fine-grained human–automation interactions. We design a concept and develop an interactive lo-fi prototype of an assisted sketching system to enable air traffic controllers to interact with automation in a fine-grained manner and to externalize mental images. Assisted sketching seems to offer a possible way to communicate different degrees of predictive certainty using visual cues and interaction. Our insights further suggest that externalization through assisted sketching could encourage exploration of future scenarios, and support communication and collaboration between air traffic controllers and between air traffic controllers and pilots. The explorative benefits for the individual decision-making process might be more evident in situations where air traffic controllers have more time for reflection, for example during planning or debriefing and in educational settings.
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| 6. |
- Saarimäki, Jonas, et al.
(författare)
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3D Residual Stresses in Selective Laser Melted Hastelloy X
- 2017
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Ingår i: Residual Stresses 2016: ICRS-10, Materials Research Proceedings 2 (2016). - : Materials Research Forum LLC. ; , s. 73-78
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Konferensbidrag (refereegranskat)abstract
- 3D residual stresses in as manufactured EOS NickelAlloy HX, produced by laser powder bed additive manufacturing, are analysed on the surface closest to the build-plate. Due to the severe thermal gradient produced during the melting and solidification process, profound amounts of thermal strains are generated. Which can result in unwanted geometrical distortion and effect the mechanical properties of the manufactured component. Measurements were performed using a four-circle goniometer Seifert X-ray machine, equipped with a linear sensitive detector and a Cr-tube. Evaluation of the residual stresses was conducted using sin2ψ method of the Ni {220} diffraction peak, together with material removal technique to obtain in-depth profiles. An analysis of the material is reported. The analysis reveals unwanted residual stresses, and a complicated non-uniform grain structure containing large grains with multiple low angle grain boundaries together with nano-sized grains. Grains are to a large extent, not equiaxed, but rather elongated.
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| 7. |
- Zäll, Erik, et al.
(författare)
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Durability of antireflective SiO2 coatings with closed pore structure
- 2023
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier. - 0927-0248 .- 1879-3398. ; 261
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Tidskriftsartikel (refereegranskat)abstract
- The use of antireflective coatings to increase the transmittance of the cover glass is a central aspect of achieving high efficiencies for solar collectors and photovoltaics alike. Considering an expected lifetime of 20–30 years for solar energy installations, the durability of the antireflective surfaces is essential. Here, a novel antireflective SiO2 coating with a hexagonally ordered closed pore structure, produced with an aerosol-based sol-gel method is benchmarked against two commercial coatings; produced with acid etching and sol-gel roll coating. The optical and mechanical properties together with contact angle characteristics were evaluated before and after various durability tests, including climate chamber tests, outdoor exposure, and abrasion. Compared to the commercial antireflective coatings with open pore structures, the novel coating performed in parity, or better, in all tests. Based on the results of humidity freeze and industrial climate chamber tests, it appears that the coating with closed pore structure has a better ability to prevent water adsorption. Additionally, the closed pore structure of the coating seems to minimize the accumulation of dirt and deposits. The abrasion and cleanability test further confirm the advantages of a closed pore structure, showcasing the coating's mechanical durability. While the coatings exhibit similar hardness and reduced elastic modulus, the closed pore coating proves to be even harder after undergoing the industrial climate chamber test, but also slightly more brittle, as indicated by the probability of crack initiation. In summary the closed pore structure is well suited for tempered and arid climates, making it a truly competitive alternative to existing antireflective coatings.
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| 8. |
- Johansson, Jonny, et al.
(författare)
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Project: EISCAT 3D
- 2007
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Annan publikation (populärvet., debatt m.m.)
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| 9. |
- Walander, Magnus, 1991, et al.
(författare)
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Efficient Experimental Approach to Evaluate Mass Transfer Limitations for Monolithic DOCs
- 2019
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Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 62:1-4, s. 391-396
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Tidskriftsartikel (refereegranskat)abstract
- The diesel oxidation catalyst (DOC, Pt/γ-Al2O3) was used in a synthetic-gas catalyst test bench to study internal mass transfer limitations during NO oxidation. A simple and fast experimental methodology, by varying the washcoat thickness in monolithic DOCs was developed and the results were evaluated using various experimental time scales. The ratio between the reaction time constant and the washcoat diffusion time constant was useful in identifying temperatures where the DOCs tested transitioned between a kinetically controlled region and an internal mass transfer controlled region. The NO conversion was shown to be significantly limited by internal mass transfer already at 175 °C for an average washcoat thickness of 110 µm.
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| 10. |
- Lundberg, Anna, 1977-, et al.
(författare)
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Microscale droplet absorption into paper for inkjet printing
- 2011
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 26:1, s. 142-150
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Tidskriftsartikel (refereegranskat)abstract
- Digital printing using high-speed inkjet technology puts heavy demands on paper's ability to rapidly absorb the liquid. This is important for both the runability during the printing process and for the print quality. In this article, the dynamics of inkjet droplet absorption and penetration is discussed. The LucasWashburn equation has been applied to experimental results from inkjet printing on paper. The ink absorption on different paper grades is discussed in terms of the physical properties of the surface such as surface energy, surface roughness and porosity. The results of this study indicate that ASA used as internal sizing reduces the absorption speed of water based dye inkjet ink and that evaporation affects the result. The Lucas-Washburn equation can be used to some extent for describing micro-scale droplet absorption into paper, depending on the properties of the paper.
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