Mutual inductance instability of the tip vortices behind a wind turbine

Two modal decomposition techniques are employed to analyse the stability of wind turbine wakes. A numerical study on a single wind turbine wake is carried out focusing on the instability onset of the trailing tip vortices shed from the turbine blades. The numerical model is based on large-eddy simulations (LES) of the Navier-Stokes equations using the actuator line (ACL) method to simulate the wake behind the Tj ae reborg wind turbine. The wake is perturbed by low-amplitude excitation sources located in the neighbourhood of the tip spirals. The amplification of the waves travelling along the spiral triggers instabilities, leading to breakdown of the wake. Based on the grid configurations and the type of excitations, two basic flow cases, symmetric and asymmetric, are identified. In the symmetric setup, we impose a 120 degrees symmetry condition in the dynamics of the flow and in the asymmetric setup we calculate the full 360 degrees wake. Different cases are subsequently analysed using dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD). The results reveal that the main instability mechanism is dispersive and that the modal growth in the symmetric setup arises only for some specific frequencies and spatial structures, e.g. two dominant groups of modes with positive growth (spatial structures) are identified, while breaking the symmetry reveals that almost all the modes have positive growth rate. In both setups, the most unstable modes have a non-dimensional spatial growth rate close to pi/2 and they are characterized by an out-of-phase displacement of successive helix turns leading to local vortex pairing. The present results indicate that the asymmetric case is crucial to study, as the stability characteristics of the flow change significantly compared to the symmetric configurations. Based on the constant non-dimensional growth rate of disturbances, we derive a new analytical relationship between the length of the wake up to the turbulent breakdown and the operating conditions of a wind turbine

Body appreciation around the world: Measurement invariance of the Body Appreciation Scale-2 (BAS-2) across 65 nations, 40 languages, gender identities, and age.

The Body Appreciation Scale-2 (BAS-2) is a widely used measure of a core facet of the positive body image construct. However, extant research concerning measurement invariance of the BAS-2 across a large number of nations remains limited. Here, we utilised the Body Image in Nature (BINS) dataset - with data collected between 2020 and 2022 - to assess measurement invariance of the BAS-2 across 65 nations, 40 languages, gender identities, and age groups. Multi-group confirmatory factor analysis indicated that full scalar invariance was upheld across all nations, languages, gender identities, and age groups, suggesting that the unidimensional BAS-2 model has widespread applicability. There were large differences across nations and languages in latent body appreciation, while differences across gender identities and age groups were negligible-to-small. Additionally, greater body appreciation was significantly associated with higher life satisfaction, being single (versus being married or in a committed relationship), and greater rurality (versus urbanicity). Across a subset of nations where nation-level data were available, greater body appreciation was also significantly associated with greater cultural distance from the United States and greater relative income inequality. These findings suggest that the BAS-2 likely captures a near-universal conceptualisation of the body appreciation construct, which should facilitate further cross-cultural research. [Abstract copyright: Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.

Body appreciation around the world: Measurement invariance of the Body Appreciation Scale-2 (BAS-2) across 65 nations, 40 languages, gender identities, and age

Abstract The Body Appreciation Scale-2 (BAS-2) is a widely used measure of a core facet of the positive body image construct. However, extant research concerning measurement invariance of the BAS-2 across a large number of nations remains limited. Here, we utilised the Body Image in Nature (BINS) dataset – with data collected between 2020 and 2022 – to assess measurement invariance of the BAS-2 across 65 nations, 40 languages, gender identities, and age groups. Multi-group confirmatory factor analysis indicated that full scalar invariance was upheld across all nations, languages, gender identities, and age groups, suggesting that the unidimensional BAS-2 model has widespread applicability. There were large differences across nations and languages in latent body appreciation, while differences across gender identities and age groups were negligible-to-small. Additionally, greater body appreciation was significantly associated with higher life satisfaction, being single (versus being married or in a committed relationship), and greater rurality (versus urbanicity). Across a subset of nations where nation-level data were available, greater body appreciation was also significantly associated with greater cultural distance from the United States and greater relative income inequality. These findings suggest that the BAS-2 likely captures a near-universal conceptualisation of the body appreciation construct, which should facilitate further cross-cultural research

Body appreciation around the world: Measurement invariance of the Body Appreciation Scale-2 (BAS-2) across 65 nations, 40 languages, gender identities, and age

The Body Appreciation Scale-2 (BAS-2) is a widely used measure of a core facet of the positive body image construct. However, extant research concerning measurement invariance of the BAS-2 across a large number of nations remains limited. Here, we utilised the Body Image in Nature (BINS) dataset - with data collected between 2020 and 2022 - to assess measurement invariance of the BAS-2 across 65 nations, 40 languages, gender identities, and age groups. Multi-group confirmatory factor analysis indicated that full scalar invariance was upheld across all nations, languages, gender identities, and age groups, suggesting that the unidimensional BAS-2 model has widespread applicability. There were large differences across nations and languages in latent body appreciation, while differences across gender identities and age groups were negligible-to-small. Additionally, greater body appreciation was significantly associated with higher life satisfaction, being single (versus being married or in a committed relationship), and greater rurality (versus urbanicity). Across a subset of nations where nation-level data were available, greater body appreciation was also significantly associated with greater cultural distance from the United States and greater relative income inequality. These findings suggest that the BAS-2 likely captures a near-universal conceptualisation of the body appreciation construct, which should facilitate further cross-cultural research

Cross section of

In this paper, the differential cross section of charmed mesons production ($$D_{s}^{\pm }$$, $$D^{0}$$, $$D^{*}$$ and $$D^{*\pm }$$ and $$D^{\pm }$$) are computed as a function of transverse momentum $$p_{T}$$ and the total cross sections. The hadronization mechanism is considered via a fragmentation process of a c heavy quark to a light-heavy meson according to Suzuki’s model. The two-cutoff phase-space slicing method has been applied to calculate the phase-space integral of two- and three-body subprocess cross sections and fragmentation function (FF) at next-to-leading order (NLO) accuracy. By using Monte Carlo (MC) techniques, we try to properly estimate the ratio of neutral to charged D-meson production $$R_{u/d}$$ and the strangeness-suppression factor $$\gamma _{s}$$. Our numerical results show that the NLO corrections of the FF have significant effect on D-mesons production and enhance the cross section ratio at NLO respect to leading order (LO) about $$50\%$$. A comparison indicates that our cross section results are in agreement (within uncertainties) with available data from ATLAS and ALICE and theoretical predictions of the fixed-order next-to-leading-logarithm (FONLL) approach and NLO parton-shower MC simulation (MC@NLO) in high-energy proton–proton (pp) collisions at $$\sqrt{s}=7TeV$$

Analytic derivation of the photon structure function

In this paper, we present the analytical solutions, based on the Laplace transform method, for the Dokshitzer–Gribov–Lipatov–Altarelli–Parisi evolution equations of the photon at the leading order (LO) and next-to-leading order (NLO) approximations in perturbative QCD. Using these solutions, we derive the singlet, non-singlet, gluon, and photon distribution functions of the photon and also the photon structure function $$F^{\gamma }_{2} (x,Q^{2})$$ at the LO and NLO approximations. We show that the resulting distribution functions are in agreement with the results of the parameterization model formulated by Gluck, Reya, and Vogt (GRV) (Phys Rev D 46(5):1973, 1992). Moreover, our numerical results of $$F^{\gamma }_{2} (x,Q^{2})$$ are comparable with the results achieved by Aurenche, Fontannaz, and Guillet (AFG) (Eur Phys J C Part Fields 44(3):395–409, 2005) and also with the experimental data released by the L3, DELPHI, OPAL, ALEPH and PLUTO collaborations

Students� evaluation of entrepreneurial university activities: A case from the Iran University of Medical Sciences

Among the key strategies in higher education is to prioritize the development of the entrepreneurial university. An appropriate entrepreneurship ecosystem in universities promotes higher education�industry relationships. Third-generation (innovative and entrepreneurial) universities and other higher education institutions depend on creativity, innovation, discovery and novelty. The aims of the present study were (a) to investigate the attitudes of Iranian students towards entrepreneurial university activities; (b) to investigate the psychometric properties of the Entrepreneurial University Activities Scale (EUAS); (c) to explore the factorial structure of the EUAS; and (d) to estimate gender-related differences. The EUAS was administered anonymously to 225 Iranian students. The mean of the EUAS total score was 43.44 (standard deviation = 26.61); Cronbach�s α was 0.98. The indicator total correlations ranged from 0.82 to 0.95 (all significant at the 0.01 level). One component was extracted, labelled �Entrepreneurial University Activities� (70.89 of the total variance). Gender-related differences were significant. Iranian students� evaluation of entrepreneurial university activities was negative, with entrepreneurial university indicators rated from none to very low. Iranian universities need to engage with industry and business. Knowledge-based companies should be supported. Technology parks, growth and accelerator centres should be equipped and updated. A sustainable financial strategy to support the development of creativity, innovation, technology, commercialization and entrepreneurship should be developed. Internationalization, as an important part of entrepreneurship strategy in a university, should be considered. The analytic hierarchy process network analysis technique is recommended for the evaluation of entrepreneurial university activities and the components influencing it. © The Author(s) 2020

Physical and mechanical properties of gelatin-clay nanocomposite

Nanoclay particles were included in a gelatin matrix and gelatin-clay nanocomposites with different clay levels were produced, successfully. Mechanical properties of gelatin-clay nanocomposite films were measured using a texture analyzer by tensile test. Water vapor permeability, solubility, opacity, and color parameters were also determined. In the absence of nanoclay water vapor permeability was 0.86 g mm/kPa m2 h and with addition of 18% nanoclay it decreased to 0.42 g mm/kPa m2 h. Tensile strength of films was directly proportional to clay content, while addition of clay caused a reduction in elongation and water vapor permeability of films. Nanoclay was able to improve some physical and mechanical properties of gelatin biofilms. © 2013 Elsevier B.V