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Characterization and modeling of biaxial plastic anisotropy in metallic sheets
(2024-08-11) Mu, Zhenkai; Liu, Jiale; Wang, Wei; Dai, Xuerui; Ma, Shibo; Hou, Yong
The anisotropic behavior of cold-rolled sheet metals has been extensively studied, typically characterized by uniaxial loading tests in different directions to determine yield strengths and plastic flow (Lankford r-values). However, biaxial principal stress states often focus solely on yield loci in the RD/TD (rolling/transverse) directions, with limited studies on other loading directions. This study analyzes the relationship between the principal stress yield loci and the material principal anisotropic stress directions based on the Hill48 yield function. Biaxial tensile tests are conducted on DP590 high-strength steel using cruciform specimens cut in various directions different from the sheet RD/TD directions. The evolution of the anisotropic yield locus and plastic flow of DP590 under biaxial tensile directions beyond the traditional RD/TD anisotropic directions is revealed. Furthermore, a modified Hill48 model that considers any principal stress direction of loading is proposed, accurately describing the continuous evolution of equi-biaxial tension stress, near-plane strain stress, and plastic flow direction for different principal stress directions of loading. The issues of failing to predict plastic flow under biaxial loadings in the original Hill48 model, and the degraded representation of existing constitutive models when accounting for out-of-plane anisotropy are addressed by decoupling the relationship between anisotropic parameters and stress state. In addition, the proposed calibration strategy of anisotropic parameters, using experimental data from various principal stress directions of loading, effectively captures the anisotropic evolution caused by changes in principal stress directions. Comprehensive evaluation and verification of the plasticity model should consider yield locus for any principal stress directions of loading, and also the normal and shear planes.
Inspecting the factors of individualizing and binding moral value orientation in the Moral Foundations Questionnaire-2 for validation—a re-analysis of data from pre-service teachers in Ghana
(2025-11-26) Wild, Steffen; Fobi, Daniel; Möhring, Michélle
Introduction: Moral foundation theory postulates two higher-order moral value orientations: individualizing and binding. In the measurement instrument of the Moral Foundations Questionnaire-2 (MFQ-2), 36 items cover the dimensions of authority, care, equality, loyalty, proportionality, and purity, which contribute to people’s individualizing and binding moral value orientation. So far, less research exists for the validation of the moral value structure in so-called non-WEIRD (western, educated, industrialized, rich, and democratic) countries like Ghana. Thus, the question arises: what is the empirical structure of moral value orientations in Ghana, and is it possible to identify the factors of individualizing and binding moral value orientations in line with the theoretical framework?.
Methods: We re-analyse data from 1,049 pre-service teachers at a university in Ghana that were gathered using a cross-sectional design and convenience sampling.
Results: Our re-analyses provide first hints of construct validity as well as criterion validity with the criteria of gender and religiosity. The abovementioned six underlying dimensions could be seen as first-order factors. The assumption of individualizing and binding moral value orientations as second-order factors in the MFQ-2 is weakly supported.
Discussion: Findings are reflected upon and discussed in terms of limitations. Further investigations in other populations of non-WEIRD countries are deemed necessary to evaluate the instrument for robustness.
Human asymmetries in AI art: syntax and writing direction effects on agent position in AI-generated images
(2025-11-17) Marklová, Anna; Delucchi Danhier, Renate
The present study investigates positional patterns in visual representations generated by two artificial intelligence (AI) models in response to textual prompts describing interactions between two animate entities. The primary objective is to assess whether the syntactic structure of a given sentence influences the spatial positioning of the agent (i.e., the entity performing the action) within the generated image. The study follows research showing that in art produced by humans, positioning of agents on the picture depends on reading-writing direction: entities mentioned first are positioned on the left side by people from cultures with left-to-right writing script disproportionately more often than on the right side. We prompted FLUX and DALL⋅E 3 with 20 English sentences, 10 passive and 10 active ones, and generated 4,000 pictures in total. In active sentences, FLUX positioned the agent to the left side of the picture significantly more often than to the right side.
In passive sentences, both models positioned the agent to the right significantly more often than to the left. In general, DALL⋅E 3 placed agents to the right more often than FLUX. The models partially copied the tendencies of humans in active sentences conditions, however, in passive sentences conditions, the models had a much stronger tendency to place agents to the right than did humans.
Our study demonstrates that these AI models, primarily influenced by English language patterns, may be replicating and even amplifying Western (English-specific) spatial biases, potentially diminishing the diversity of visual representation influenced by other languages and cultures. This has consequences for the visual landscape around us: AI pictorial art is overflowing our visual space and the information that we have imprinted into pictures as intrinsically human is changing.
Bottom-up production of injectable itraconazole suspensions using membrane technology
(2024-03-06) Anjum, Fatima; Viville, Thaïsa; Nandi, Snehashis; Wessner, Maximilian; Witte, Bruno De; Collas, Alain; Sadowski, Gabriele
Bottom-up production of active pharmaceutical ingredient (API) crystal suspensions offers advantages in surface property control and operational ease over top-down methods. However, downstream separation and concentration pose challenges. This proof-of-concept study explores membrane diafiltration as a comprehensive solution for downstream processing of API crystal suspensions produced via anti-solvent crystallization. It involves switching the residual solvent (N-methyl-2-pyrrolidone, NMP) with water, adjusting the excipient (d-α-Tocopherol polyethylene glycol 1000 succinate, TPGS) quantity, and enhancing API loading (solid concentration) in itraconazole crystal suspensions. NMP concentration was decreased from 9 wt% to below 0.05 wt% (in compliance with European Medicine Agency guidelines), while the TPGS concentration was decreased from 0.475 wt% to 0.07 wt%. This reduced the TPGS-to-itraconazole ratio from 1:2 to less than 1:50 and raised the itraconazole loading from 1 wt% to 35.6 wt%. Importantly, these changes did not adversely affect the itraconazole crystal stability in suspension. This study presents membrane diafiltration as a one-step solution to address downstream challenges in bottom-up API crystal suspension production. These findings contribute to optimizing pharmaceutical manufacturing processes and hold promise for advancing the development of long-acting API crystal suspensions via bottom-up production techniques at a commercial scale.
Bootstrap consistency for the Mack bootstrap
(2024-01-17) Steinmetz, Julia; Jentsch, Carsten
Mack's distribution-free chain ladder reserving model belongs to the most popular approaches in non-life insurance mathematics. Proposed to determine the first two moments of the reserve, it does not allow to identify the whole distribution of the reserve. For this purpose, Mack's model is usually equipped with a tailor-made bootstrap procedure. Although widely used in practice to estimate the reserve risk, no theoretical bootstrap consistency results exist that justify this approach.
To fill this gap in the literature, we adopt the framework proposed by Steinmetz and Jentsch (2022) to derive asymptotic theory in Mack's model. By splitting the reserve into two parts corresponding to process and estimation uncertainty, this enables - for the first time - a rigorous investigation also of the validity of the Mack bootstrap. We prove that the (conditional) distribution of the asymptotically dominating process uncertainty part is correctly mimicked by Mack's bootstrap if the parametric family of distributions of the individual development factors is correctly specified. Otherwise, this is not the case. In contrast, the (conditional) distribution of the estimation uncertainty part is generally not correctly captured by Mack's bootstrap. To tackle this, we propose an alternative Mack-type bootstrap, which is designed to capture also the distribution of the estimation uncertainty part.
We illustrate our findings by simulations and show that the newly proposed alternative Mack bootstrap performs superior to the Mack bootstrap.