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- 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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| 4. |
- Ask, Anna
(författare)
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Electro-viscoelastic Modeling of Electroactive Polymers
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- While traditionally treated separately, the research disciplines dealing with electromagnetic fields respectively continuum mechanics are naturally connected. Not only are the basic equations formulated in a similar way, but the presence of electromagnetic fields affect the balance equations of continuum mechanics and likewise, the presence of material continua affect the electromagnetic fields. For certain classes of materials, the interactions between electromagnetic fields and the mechanical continuum is notably present. Such materials include piezoelectrics, which deform in the presence of electric fields and reversibly generate charge when they are deformed. Piezoelectric materials have been known for a long time and are used in a wide variety of technological applications. More recently, other materials where electromagnetic fields give rise to mechanical effects have been discovered and made use of. Electroactive polymers (EAP) is one class of such materials. The EAP considered in this thesis react to electric input by mechanical deformation. It has been shown that they have properties that make them comparable to natural muscle. Areas where EAP are considered include biomimetics and microrobotics, where traditional engineering materials may not be possible to use. In this thesis, these materials are treated from a continuum mechanics point of view. A phenomenological constitutive model is established which include the electromechanical behavior as well as mechanical properties traditionally associated with elastomers, such as viscosity. Furthermore, the balance equations relevant for electromechanical continua are solved numerically by means of the finite element method for some representative boundary value problems.
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| 6. |
- Ask, Anna, et al.
(författare)
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Electromechanics of polyurethane elastomers
- 2011
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Konferensbidrag (refereegranskat)abstract
- It is well known that electroactive polymers (EAP) deform under electric fields. An advantage of EAP is that it may undergo deformations much larger than those capable by electroactive ceramics, however at comparatively low forces. As common for polymers, EAP exhibit time-dependent material behavior, i.e. an electro-viscoelastic effect. In the modeling the deformation as well as the electric potential are introduced as global degrees of freedom, the internal variables accounting for the viscous response are incorporated at the so-called constitutive level. The proposed model is calibrated against experimental data, and a simple coupled finite element example is studied to show the applicability of the finite deformation electro-viscoelastic formulation proposed.
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| 7. |
- Ask, Anna, et al.
(författare)
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Electrostriction in electro-viscoelastic polymers
- 2012
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Ingår i: Mechanics of Materials. - : Elsevier BV. - 0167-6636. ; 50, s. 9-21
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Tidskriftsartikel (refereegranskat)abstract
- Electrostrictive polyurethane (PU) elastomers belong to the class of materials commonly referred to as electroactive polymers (EAP). These materials have their use in a variety of applications, including biomimetics and microrobotics where traditional engineering components may fall short. PU is one of the materials considered for so called dielectric actuators, where the electromechanical response is generally due to Coulomb forces on the actuator electrodes, giving rise to a compressive pressure and thereby large deformations of the polymer. On the other hand, for more moderate electric fields, which may be more attractive in certain applications, a large part of the electroactive response for PU elastomers is due to inherent electrostriction. The latter phenomena is the focus of this work. As is common in elastomers, PU elastomers are viscoelastic. A coupled electro-viscoelastic phenomenological constitutive model for electrostrictive PU is proposed and fitted to experimental data available in the literature. The possibility of performing simulations of EAP is of interest as the number of applications grow. Considering this, the computational model is embedded in a coupled finite element formulation and, based on this, representative simulations of inhomogeneous boundary value problems are presented.
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