| 1. |
- Jones, Benedict C, et al.
(författare)
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To which world regions does the valence-dominance model of social perception apply?
- 2021
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Ingår i: Nature Human Behaviour. - : Springer Science and Business Media LLC. - 2397-3374. ; 5:1, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Over the past 10 years, Oosterhof and Todorov's valence-dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgements of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov's methodology across 11 world regions, 41 countries and 11,570 participants. When we used Oosterhof and Todorov's original analysis strategy, the valence-dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions, we observed much less generalization. Collectively, these results suggest that, while the valence-dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods and correlate and rotate the dimension reduction solution. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 5 November 2018. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.7611443.v1 .
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| 2. |
- Kumar, M., et al.
(författare)
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Development of nano-crystalline cold sprayed Ni-20Cr coatings for high temperature oxidation resistance
- 2015
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Ingår i: Surface & Coatings Technology. - 0257-8972 .- 1879-3347. ; 266, s. 122-133
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Tidskriftsartikel (refereegranskat)abstract
- In the current investigation a pre-synthesized nano-crystalline Ni-20Cr powder was deposited by cold-spray technique on SA 516 steel. The powder was synthesized by ball milling approach. The nano-crystallinity of the developed coating was established by crystallite size measurements from XRD profile, which was further endorsed by TEM analysis. High-temperature oxidation behavior of uncoated and coated samples was studied under cyclic isothermal conditions at 900 degrees C for 50 cycles in a laboratory tube furnace. The oxidation rates for the bare and coated steel were evaluated in terms of weight gain data. Different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and transmission electron microscopy (TEM) analyses were utilized to characterize the oxide scale. The hardness and oxidation resistance of the steel increased after the application of coating. The reduction in oxidation rate of the base steel was 94%. Moreover, the developed nanostructured coating was observed to reduce weight gain by 64% in comparison with micron-sized Ni-20Cr cold spray coating thus offers a higher oxidation resistance. This may be attributed to relatively denser structure, lower porosity and lower oxide content of the nanostructured coating. (C) 2015 Elsevier B.V. All rights reserved.
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| 3. |
- Kaur, N., et al.
(författare)
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Study of mechanical properties and high temperature oxidation behavior of a novel cold-spray Ni-20Cr coating on boiler steels
- 2015
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 328, s. 13-25
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Tidskriftsartikel (refereegranskat)abstract
- In the current investigation, high temperature oxidation behavior of a novel cold-spray Ni-20Cr nano-structured coating was studied. The nanocrystalline Ni-20Cr powder was synthesized by the investigators using ball milling, which was deposited on T22 and SA 516 steels by cold spraying. The crystallite size based upon Scherrer's formula for the developed coatings was found to be in nano-range for both the substrates. The accelerated oxidation testing was performed in a laboratory tube furnace at a temperature 900 degrees C under thermal cyclic conditions. Each cycle comprised heating for one hour at 900 degrees C followed by cooling for 20 min in ambient air. The kinetics of oxidation was established using weight change measurements for the bare and the coated steels. The oxidation products were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) and X-ray mapping techniques. It was found from the results that the coating was successful in reducing the weight gain of SA213-T22 and SA 516-Grade 70 steel by 71% and 94%, respectively. This may be attributed to relatively denser structure, lower porosity and lower oxide content of the coating. Moreover, the developed nano-structured Ni-20Cr powder coating was found to perform better than its counterpart micron-sized Ni-20Cr powder coating, in terms of offering higher oxidation resistance and hardness. (C) 2014 Elsevier B.V. All rights reserved.
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| 4. |
- Koppoju, S., et al.
(författare)
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Evolution of texture during laser surface treatment of an austenitic manganese steel
- 2015
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Ingår i: Materials Characterization. - 1044-5803 .- 1873-4189. ; 102, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the evolution of microstructure and texture of an austenitic manganese steel (1.34C-13.6Mn-0.45Si-Fe, wt.%) during surface modification using a high power diode laser. Strong (002) texture has been observed on the surface of the steel with increase in interaction time. It has been found that columnar type dendrites are responsible for the strong texture which is favorably grown in the < 001 > direction perpendicular to the substrate plane. The growth of dendrites with specific crystallographic direction is governed by the interfacial energy anisotropy and thermal gradient direction. (C) 2015 Elsevier Inc. All rights reserved.
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| 5. |
- Chourushi, T., et al.
(författare)
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Thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow based on second-order non-Navierâ-Fourier constitutive model
- 2022
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier Ltd. - 0017-9310 .- 1879-2189. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- The thermal and flow characteristics of nonequilibrium monatomic, diatomic, and polyatomic gases in cylindrical Couette flow are investigated using first- and second-order Boltzmann-Curtiss-based constitutive models. The mixed modal discontinuous Galerkin scheme is used for solving the conservation laws in conjunction with the Maxwell velocity-slip and Smoluchowski temperature-jump boundary conditions. Also derived are new analytic solutions for compressible cylindrical Couette gas flow including the temperature profile, and they are used to verify the numerical scheme. Further, the second-order non-Navier-Fourier constitutive relations are derived for the cylindrical coordinates. Various abnormal behaviour is found in the second-order constitutive model, such as non-zero normal stress and excess normal stress, non-zero tangential heat flux, and flattened pressure and density profiles. The physical mechanisms behind this abnormal behaviour are found to be similar to the Knudsen layer in planar Couette gas flow, and the curvature of the cylindrical geometry does not affect the fundamental second-order physics. Moreover, two new abnormal mechanisms are found in diatomic and polyatomic gases: (i) the subtle interplay of excess normal stress (and bulk viscosity) with the nonlinear coupled constitutive relation, and (ii) the combined role of the bulk viscosity ratio and the specific heat ratio.
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| 6. |
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| 7. |
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| 8. |
- Kumar, Rajiv, et al.
(författare)
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Effect of chromium and aluminum addition on anisotropic and microstructural characteristics of ball milled nanocrystalline iron
- 2016
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 671, s. 164-169
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Tidskriftsartikel (refereegranskat)abstract
- Prior studies on synthesis of nanocrystalline elements have discussed the effect of ball milling on lattice parameter, crystallite size, and micro-strain. For elemental milled powders, the anisotropic peak broadening does not change with increasing milling time. However, the effect of alloying addition on the anisotropic behavior of ball milled nanocrystalline powders remains an unexplored area. Here we report the effect of chromium and aluminum addition on the anisotropic behavior of iron in nanocrystalline Fe–20Cr–5Al (wt%) alloy powders synthesized by ball milling. The experimental results show that the anisotropic behavior of iron changes towards isotropic with milling. This change was also correlated to the theoretically calculated anisotropic factor from the change in elastic constant of iron due to milling. Addition of alloying elements exhibited a monotonic rise in the lattice parameter with crystallite size, which was attributed to the excess grain boundary interfacial energy and excess free volume at grain boundaries. Transmission electron microscopy image confirmed the crystallite size and nature of dislocation obtained using modified Williamson-Hall method.
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| 9. |
- Das, D. K., et al.
(författare)
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Effect of Al content on microstructure and cyclic oxidation performance of Pt-aluminide coatings
- 2002
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Ingår i: Oxidation of Metals. - 0030-770X .- 1573-4889. ; 57:3-4, s. 245-266
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Al content, i.e., the amount of Al picked up during aluminizing, on the microstructure and cyclic oxidation properties of Pt-aluminide coatings has been investigated. The cast Ni-base superalloy CM-247 was used as the substrate material and a single-step, high-activity pack aluminizing process was used to produce the Pt-aluminide coatings. The Al content of these coatings was varied by using packs with different compositions of the Al source. Pt-aluminide coatings having three different Al contents, namely 6.5, 16, and 21 mg cm-2, were evaluated for their cyclic oxidation resistance at 1200°C in air. It was found that the Pt-aluminide coatings, irrespective of their Al contents, evolve in the same manner during aluminizing and result in a three-layer structure with an outer PtAl2 + NiAl two-phase layer, an intermediate NiAl layer, and the inner interdiffusion layer. The stability of this three-layer coating structure over long periods of aluminizing, however, is dependent on the availability of Al from the pack during this period. Below a certain threshold Al availability, the two-phase outer layer transforms to a single-phase NiAl structure causing the coating to change from its three-layer structure to a two-layer one. Cyclic oxidation results indicate that, while a minimum Al content in Pt-aluminide coatings is essential for deriving the best oxidation performance, increasing the Al content beyond a certain level does not significantly enhance oxidation behavior. The effect of Al content on aspects, such as coating degradation and nature of coating-surface damage during cyclic oxidation, is also discussed.
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| 10. |
- Das, D. K., et al.
(författare)
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Effect of prealuminizing diffusion treatment on microstructural evolution of high-activity pt-aluminide coatings
- 2000
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Ingår i: Metallurgical and Materials Transactions. A. - 1073-5623 .- 1543-1940. ; 31:8, s. 2037-2047
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Tidskriftsartikel (refereegranskat)abstract
- The effect of prealuminizing (or prior) diffusion treatment on the evolution of Pt-aluminide coatings on the Ni-based superalloy CM-247 has been studied by using a single-step, high-activity aluminizing process. Coatings generated without any prior diffusion treatment, as well as those formed by adopting two extreme prior-diffusion schedules (at 850 °C for 0.5 hours and at 1034 °C for 5 hours), were investigated by analyzing the coating structures at various stages of aluminizing. When the dilution of the Pt layer, caused by its interdiffusion with the substrate during the prior diffusion treatment, is only marginal (as in the case of no prior diffusion and diffusion at 850 °C for 0.5 hours), the equilibrium Pt-aluminide coating structure evolves through the formation of two transient layers during the initial stages of aluminizing. In contrast, for diffusion at 1034 °C for 5 hours, which results in extensive dilution of the Pt layer, the two-phase equilibrium structure (PtAl2 in a matrix of NiAl) in the outer layer of the coating is found to develop during very early stages of aluminizing and remains unchanged, even over extended periods of aluminizing. Further, in the case of prior diffusion at 1034 °C for 5 hours, Pt is found to remain distributed to a greater extent over the entire thickness of the coating than in the cases of limited prior diffusion treatment. The present findings underline the significance of the nature of the prior-diffusion schedule on the microstructural evolution of Pt-aluminide coatings. It has also been found that a prealuminizing diffusion treatment is particularly important for Pt-aluminide coatings from the point of view of coating adhesion to the substrate.
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