Microscale diffusion-mechanics model for a polymer-based solid-state battery cathode

A non-linear microscale diffusion-mechanics model combining mass transport and linear momentum balance equations, with elasto-viscoplastic polymer constitutive law and interfacial traction-separation law is proposed to provide a new insight into the effects of viscoplasticity and interfacial damage on the in situ diffusive-mechanical behaviour of a polymer-based cathode for a solid-state battery (SSB). Diffusion and mechanics are coupled through two mechanisms: (1) active particle (AP) volumetric change dependence on Li concentration, and (2) interfacial flux dependence on mechanical opening. The model is resolved for a simple cathode microstructure using an axisymmetric unit cell concept, and integrated with the non-linear finite-element solver ABAQUS with the help of its user subroutines (UMAT and UINTER). Finite-element simulations reveal that plastic deformations of the polymer due to volumetric changes of the AP reduce the value of the interfacial opening displacement, which is desirable for maintaining interfacial flux. The results also demonstrate that slower battery charging rates may lead to a softer polymer response, and thus a smaller interfacial gap. Moreover, a comparison between the linear elastic and current elasto-viscoplastic models for the polymer electrolyte shows that even 5% volumetric shrinkage of the AP leads to an overprediction of the interfacial opening with the linear elastic material law, which limits its validity in modelling polymer-based SSBs

High-contrast problems in linear elasticity for a coated half-space

The thesis is concerned with asymptotic analysis of static as well as dynamic problems for a solid coated by a thin isotropic elastic layer with a high contrast in their material parameters. First, the static anti-plane shear deformation problem is considered with the layer being relatively soft or stiff in order to investigate the behaviour of the coating. The two-parametric asymptotic procedure is introduced motivated by the scaling obtained from the exact solution of a model problem. As a result, Winkler-type behaviour appears for a relatively soft coating, whereas for a relatively stiff one, the equations of plate shear are valid. Further, the formulation is extended to a 3D case with vertical force applied at the surface aiming at asymptotic investigation of the area of validity of the Winkler-Fuss hypothesis and the Kirchhoff plate theory. It is established that the aforementioned theories are valid only at a rather high contrast in stiffness of the layer and the half space. However, a uniformly valid formula is deduced in case of a layer being soft, and for low contrast with the coating being stiff, several approximate formulations are suggested based on the reduced problems for the half space. Then, the problem is considered in dynamic formulation yielding the higher order effective boundary conditions modelling the presence of the coating layer. The obtained results indicate again the inconsistency of the conditions earlier presented in [22]. The validity of the asymptotic results is demonstrated by comparison with the long-wave expansion of the exact solutions of plane and anti-plane time-harmonic problems for the coating. Finally, the dynamic problem for a coated half-space with clamped surface is considered. The exact solutions are obtained in an anti-plane and plane strain formulations resulting in the range of material parameters for which the sought for localised wave exists. The effective boundary conditions are obtained and the model for Rayleigh wave field is applied for the layer being thin and soft, leading to an explicit correction to the classical Rayleigh wave speed

Education as a social and cultural phenomenon

In the article the attention is concentrated on the culture as a complex polysyllabic phenomenon. Education is regarded as one of the culture phenomenon. Three trends in analysis of interaction culture and education studied in scientific researches are revealed. The interdependence of culture and education is determined. The analysis of modern understanding of education has been done. The interpretation of person as a middleman between culture and education and using of the conception «person of culture» is motivated

Two-Parametric Analysis of Anti-Plane Shear Deformation of a Coated Elastic Half-Space

The anti-plane shear deformation problem of a half-space coated by a soft or a stiff thin layer is considered. The two-term asymptotic analysis is developed motivated by the scaling for the displacement and stress components obtained from the exact solution of a model problem for a shear harmonic load. It is shown that for a rather high contrast in stiffness of the layer and the half-space Winkler-type behaviour appears for a relatively soft coating, while for a relatively stiff one, the equations of plate shear are valid. For low contrast, an alternative approximation is suggested based on the reduced continuity conditions and the fact that the applied load may be transmitted to the interface. In case of a stiff layer, a simpler problem for a homogeneous half-space with effective boundary condition is also formulated, modelling the effect of the coating, while for a relatively soft layer a uniformly valid approximate formula is introduced

Fostering critical thinking skills among future teachers

Today, a person who thinks critically is able to conduct a dialogue, determine the nature of any problem and find alternative solutions, and distinguish fact from assumption. This person is not afraid to question established opinions and judgments. That is why such kind of people are considered to be competitive and in demand on the labor market. The article, based on modern scientific positions, reveals the meaning of “critical thinking”. The development of critical thinking is based on observation skills; on the ability to ask questions and find the necessary resources; on the ability to check beliefs, assumptions and opinions, contrary to the evidence; on the ability to distinguish and identify a problem; on the ability to assess the validity of statements and arguments; and on the ability to find and make smart decisions, and understand the logic and logical arguments. The authors of the article found that the process of solving pedagogical problems was the basic unit of critical thinking skills among future teachers. The availability of critical thinking skills among future teachers is determined by using a critical thinking test, developed by Lauren Starkey, an American author (Starkey, 2004). The analysis of the survey results shows that the majority of respondents have an average level of critical thinking skills. The average level of critical thinking skills indicates that an average future teacher’s forms of thinking are unevenly developed. That is why it is difficult for a future teacher to make important decisions. We propose to foster critical thinking skills by solving pedagogical problems, which involves the use of modern interactive forms, methods and techniques of teaching

Predictors of enhancing human physical attractiveness : data from 93 countries

International audienc

Predictors of enhancing human physical attractiveness: Data from 93 countries

People across the world and throughout history have gone to great lengths to enhance their physical appearance. Evolutionary psychologists and ethologists have largely attempted to explain this phenomenon via mating preferences and strategies. Here, we test one of the most popular evolutionary hypotheses for beauty-enhancing behaviors, drawn from mating market and parasite stress perspectives, in a large cross-cultural sample. We also test hypotheses drawn from other influential and non-mutually exclusive theoretical frameworks, from biosocial role theory to a cultural media perspective. Survey data from 93,158 human participants across 93 countries provide evidence that behaviors such as applying makeup or using other cosmetics, hair grooming, clothing style, caring for body hygiene, and exercising or following a specific diet for the specific purpose of improving ones physical attractiveness, are universal. Indeed, 99% of participants reported spending >10 min a day performing beauty-enhancing behaviors. The results largely support evolutionary hypotheses: more time was spent enhancing beauty by women (almost 4 h a day, on average) than by men (3.6 h a day), by the youngest participants (and contrary to predictions, also the oldest), by those with a relatively more severe history of infectious diseases, and by participants currently dating compared to those in established relationships. The strongest predictor of attractiveness-enhancing behaviors was social media usage. Other predictors, in order of effect size, included adhering to traditional gender roles, residing in countries with less gender equality, considering oneself as highly attractive or, conversely, highly unattractive, TV watching time, higher socioeconomic status, rightwing political beliefs, a lower level of education, and personal individualistic attitudes. This study provides novel insight into universal beauty-enhancing behaviors by unifying evolutionary theory with several other complementary perspectives

Predictors of enhancing human physical attractiveness: Data from 93 countries

International audienc