| 1. |
- Dahlman, Christian, et al.
(author)
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Prototype effect and the persuasiveness of generalizations
- 2015
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In: Review of Philosophy and Psychology. - : Springer Science and Business Media LLC. - 1878-5166 .- 1878-5158. ; 7:1, s. 163-180
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Journal article (peer-reviewed)abstract
- An argument that makes use of a generalization activates the prototype for the category used in the generalization. We conducted two experiments that investigated how the activation of the prototype affects the persuasiveness of the argument. The results of the experiments suggest that the features of the prototype overshadow and partly overwrite the actual facts of the case. The case is, to some extent, judged as if it had the features of the prototype instead of the features it actually has. This prototype effect increases the persuasiveness of the argument in situations where the audience finds the judgment more warranted for the prototype than for the actual case (positive prototype effect), but decreases persuasiveness in situations where the audience finds the judgment less warranted for the prototype than for the actual case (negative prototype effect).
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| 2. |
- Dahlman, Christian, et al.
(author)
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The Effect of Imprecise Expressions in Argumentation-Theory and Experimental Results
- 2012
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In: ARGUMENTATION 2012: International Conference on Alternative Methods of Argumentation in Law. - 9788021059481 ; , s. 15-30
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Conference paper (peer-reviewed)abstract
- We investigate argumentation where an expression is substituted with a less precise expression. We propose that the effect that this deprecization has on the audience be called deprecization effect. When the audience agrees more with the less precise version of the argument, there is a positive deprecization effect. We conducted an experiment where the participants were presented with a court room scenario. The results of the experiment confirm the following hypothesis: If the participants find it hard to agree with the precise version of the argument and accept the use of the imprecise term, they will agree more with the imprecise version of the argument. Furthermore, we show that a person who reacts in this way to deprecization commits the fallacy of equivocation.
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| 3. |
- Rieth, M., et al.
(author)
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A brief summary of the progress on the EFDA tungsten materials program
- 2013
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 442:1-3, s. S173-S180
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Journal article (peer-reviewed)abstract
- The long-term objective of the European Fusion Development Agreement (EFDA) fusion materials programme is to develop structural and armor materials in combination with the necessary production and fabrication technologies for reactor concepts beyond the International Thermonuclear Experimental Reactor. The programmatic roadmap is structured into four engineering research lines which comprise fabrication process development, structural material development, armor material optimization, and irradiation performance testing, which are complemented by a fundamental research programme on "Materials Science and Modeling." This paper presents the current research status of the EFDA experimental and testing investigations, and gives a detailed overview of the latest results on materials research, fabrication, joining, high heat flux testing, plasticity studies, modeling, and validation experiments.
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| 4. |
- Rieth, M., et al.
(author)
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Recent progress in research on tungsten materials for nuclear fusion applications in Europe
- 2013
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In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 432:1-3, s. 482-500
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Research review (peer-reviewed)abstract
- The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme's main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments.
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| 5. |
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| 6. |
- Wahlberg, Sverker, et al.
(author)
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Fabrication of Nanostructured W-Y2O3 Materials by Chemical Methods
- 2012
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In: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 22:25, s. 12622-12628
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Journal article (peer-reviewed)abstract
- A novel method for the fabrication of highly uniform oxide dispersion-strengthened (ODS) materials made by chemical processing is presented. The powders are fabricated by a two-step route starting with a chemical synthesis at room temperature, producing nanocrystalline yttrium doped tungsten trioxide hydrate precursor powders. Thermogravimetric analysis with evolved gas analysis revealed the presence of ammonium nitrate in the precursors. The second step is the reduction of the precursor in a hydrogen atmosphere at 600 and 800 degrees C. The reduced powders, containing W-1.2%Y2O3, showed two types of tungsten particles, cube-shaped with a size less than 250 nm and finer particles (<50 nm) of both spherical and cubic shape. The powder was consolidated by spark plasma sintering at 1100 degrees C, producing a bulk material with a relative density of 88%. Characterization of the sintered materials by high resolution scanning electron microscopy revealed a uniform microstructure with tungsten grains of less than 300 nm and nanosized oxide particles uniformly dispersed at the tungsten grain boundaries, as well as inside the tungsten grains. Experimental determination of the elastic properties was conducted by nanoindentation tests and fracture toughness was studied by radial indentation cracking.
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| 7. |
- Wahlberg, Sverker, et al.
(author)
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Nanostructured hard material composites by molecular engineering .1. Synthesis from soluble tungstate salts
- 1997
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In: Nanostructured materials. - 0965-9773 .- 1872-9150. ; 9:1-8, s. 105-108
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Journal article (peer-reviewed)abstract
- A key issue, in the development of very fine grades, is to produce materials with high uniformity. The aqueous chemistry of tungsten offers several possibilities for the synthesis of homogenous molecular precursors containing W and Co mixed on the atomic scale. Powders containing (NH4)(8)[H2Co2W11O40] have been prepared starting from sodium tungstate or ammonium metatungstate. Nanophase powders of W-Co and WC-Co powders were obtained after reduction at 750 degrees C under H-2 and carburisation at 1000 degrees C under H-2/CH4. Hard materials with submicron microstructures were obtained after sintering at 1410 degrees C.
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| 8. |
- Wahlberg, Sverker, 1965-
(author)
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Nanostructured Tungsten Materials by Chemical Methods
- 2011
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Licentiate thesis (other academic/artistic)abstract
- Tungsten based-materials are used in many different technical fields, particularly in applications requiring good temperature and/or erosion resistance. Nanostructuring of tungsten alloys and composites has the potential to dramatically improve the materials’ properties, enhancing the performance in present applications or enabling totally new possibilities. Nanostructured WC-Co composites have been the focus of researchers and industries for over two decades. New methods for powder fabrication and powder consolidation have been developed. However, the fabrication of true nanograined WC-Co materials is still a challenge. Nanostructured tungsten composites for applications as plasma facing materials in fusion reactors have in recent years attracted a growing interest. This Thesis summarizes work on the development of chemical methods for the fabrication of two different types of nanostructured tungsten based materials; WC-Co materials mainly aimed at cutting tools applications and W-ODS composites with rare earth oxide particles, intended as plasma facing materials in future fusion reactors. The approach has been to prepare powders in two steps: a) synthesis of uniform powder precursors containing ions of tungsten and the doping elements by co-precipitation from aqueous solutions, and b) further processing of the precursors into W or WC based nano-composite powders. Highly homogenous W and Co containing powder precursors for WC-Co composites were prepared via two different routes. Keggin-based precursors ((NH4)8[H2Co2W11O40]) with agglomerates of sizes up to 50 μm, were made from sodium tungstate or ammonium metatungstate and cobalt acetate. The powder composition corresponded to 5.2 % Co in the final WC-Co composites. In a second approach, paratungstate-based precursors (Cox(NH4)10-2x[H2W12O42]) were prepared from ammonium paratungstate (APT) and cobalt hydroxide with different compositions corresponding to 3.7 to 9.7 % Co in WC-Co. These particles had a plate-like morphology with sides of 5-20 μm and a thickness of less than 1 μm. Both precursors were processed and sintered into highly uniform microstructures with fine scale (<1μm). The processing of paratungstate-based precursors was also further investigated. Nanostructured WC-Co powders with grains size of less than 50 nm by decreasing processing temperatures and by applying gas phase carburization. W-ODS materials were fabricated starting from ammonium paratungstate and rare earth elements (Y or La). Paratungstate-based precursors were prepared with different homogeneity and particle sizes. The degree of the chemical uniformity varied with the particle size from ca 1 to 30 μm. Tungsten trioxide hydrate-based precursors made from APT and yttrium nitrate under acidic conditions had dramatically higher homogeneity and smaller particle size. The crystallite size was decreased to a few nanometers. These precursors were further processed to composite nanopowder and sintered to a nanostructured W-1.2%Y2O3 composite with 88% relative density. In summary, APT can be converted to highly homogenous powder precursors of different compositions. The transformations are carried out in aqueous suspensions as a solvent mediated process, in which the starting material dissolves and the precursor precipitates. Powders with fine scale morphologies are obtained, e.g. plate-like particles with thickness less than 1 μm or spherical particles with size of a few nanometers. These precursors were processed further in to nano-sized composite powders and sintered to highly uniform tungsten composites with fine microstructures.
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