Viscoelastoplastic cyclic behaviour of sail materials

International audienceA tensorial visco-elasto-hysteresis model has been used previously in order to describe the thermomechanical behaviour of woven fabrics. Thus, it takes into account the essential features of behaviour, such as the steady state viscous stress as a function of strain and strain rate, the time-independent irreversible behaviour and the instantaneous modulus increasing with the strain. The aim of the study is to suggest the interest of the theory in the field of sail fabrics concerning characterization, testing and design. Moreover, we focus attention on two questions which are of fundamental interest, both at the level of principles and in the field of technological research, namely the viscous behaviour of sail fabrics and his nonlinear character

Developments in finite element simulations of continuous casting

peer reviewedTwo complementary approaches of steel continuous casting modelling using the finite element code LAGAMINE have been developed in the M&S Department. We propose here a description of the context in which the study started, then a description of both macroscopic and mesoscopic approaches. The first one describes the whole continuous casting process, from the free surface in the mould and through the entire machine, including thermal and mechanical behaviour of the steel. The second approach focuses on the prediction of cracks and is developed at the grain scale. Some results are also presented for both models

The magnitude of the effect of calf muscles fatigue on postural control during bipedal quiet standing with vision depends on the eye-visual target distance

The purpose of the present experiment was to investigate whether, with vision, the magnitude of the effect of calf muscles fatigue on postural control during bipedal quiet standing depends on the eye-visual target distance. Twelve young university students were asked to stand upright as immobile as possible in three visual conditions (No vision, Vision 1m and Vision 4m) executed in two conditions of No fatigue and Fatigue of the calf muscles. Centre of foot pressure displacements were recorded using a force platform. Similar increased variances of the centre of foot pressure displacements were observed in the fatigue relative to the No fatigue condition for both the No vision and Vision 4m conditions. Interestingly, in the vision 1m condition, fatigue yielded: (1) a similar increased variance of the centre of foot pressure displacements to those observed in the No vision and Vision 4m conditions along the medio-lateral axis and (2) a weaker destabilising effect relative to the No vision and Vision 4m conditions along the antero-posterior axis. These results evidence that the ability to use visual information for postural control during bipedal quiet standing following calf muscles fatigue is dependent on the eye-visual target distance. More largely, in the context of the multisensory control of balance, the present findings suggest that the efficiency of the sensory reweighting of visual sensory cues as the neuro-muscular constraints acting on the subject change is critically linked with the quality of the information the visual system obtains

Physiological Targets of Artificial Gravity: The Sensory-Motor System

This chapter describes the pros and cons of artificial gravity applications in relation to human sensory-motor functioning in space. Spaceflight creates a challenge for sensory-motor functions that depend on gravity, which include postural balance, locomotion, eye-hand coordination, and spatial orientation. The sensory systems, and in particular the vestibular system, must adapt to weightlessness on entering orbit, and again to normal gravity upon return to Earth. During this period of adaptation, which persists beyond the actual gravity-level transition itself the sensory-motor systems are disturbed. Although artificial gravity may prove to be beneficial for the musculoskeletal and cardiovascular systems, it may well have negative side effects for the neurovestibular system, such as spatial disorientation, malcoordination, and nausea

Creating flexibility indicators for the Dutch education system

This technical report comprises a description of the data and the code to create flexibility indicators for the Dutch Education system. The data that is used to make the indicators with is the Netherlands Cohort Study of Education (Nationaal Cohortonderzoek Onderwijs, NCO) (Haelermans et al., 2020), which is available at Statistics Netherlands’ (CBS) secured Remote Access environment (RA), which access is granted under certain conditions for statistical and scientific research (see Statistics Netherlands, 2023)

Flexibility in the Dutch education system:how institutional characteristics modify students’ educational careers

Early selection of students in secondary school often goes hand-in-hand with inequality of opportunities in the education system. Though, in some education systems it does not. Flexibility in the sorting and selection of students has been put forward as an explanation for this. This thesis inquires this concept of flexibility empirically. It shows for the Dutch secondary education system that there is indeed a considerable difference between schools in the stringency with which the selection is enforced. The thesis further focuses on how deviating from the standard pathway through the system takes place. Important ways to fare through the system are combining different levels of education after sorting and placing students in a school with a variety of levels. If those flexibility measures are implemented, students have a better chance of outperforming themselves, can selection at the start be more lenient, and schools themselves can maintain a good quality

Study Protocol on Cognitive Performance in Bulgaria, Croatia, and the Netherlands: The Normacog Brief Battery

The Normacog Brief Battery (NBB) provides a comprehensive overview of an individual’s cognitive functioning within a short amount of time. It was originally developed for the Spanish population in Spain. However, there is a considerable need for brief batteries in clinical neuropsychological assessment, especially in eastern European countries. Cultural background and other individual characteristics—such as age, level of education, and sex—are shown to influence both cognition and patients’ performance on neuropsychological tests. Therefore, it is important to develop understanding of how and why culture impacts on cognitive testing and determine which sociodemographic variables affect cognitive performance. The current study aims to translate, adapt, and standardize the NBB in Bulgaria, Croatia, and the Netherlands, and to analyze the effect of sex, age, and education level on cognitive performance between these three countries. This brief battery assesses eleven cognitive domains, including those most currently relevant in cognition such as premorbid intelligence, attention, executive function, processing speed, and memory. The translation and adaptation of the battery for different cultures will be done using the back-translation process. After exclusion criteria, the current study will include a total sample of three hundred participants (≥18 years old). The samples of 100 participants per country will be balanced through the consideration of their age and level of education. Effects of the sociodemographic variables (age, level of education, and sex) on cognitive performance are expected. Furthermore, this relationship is expected to differ across countries. A multivariate hierarchical linear regression will be used and exploratory analysis will be carried out to investigate further effects. The results will be particularly valuable for future research and assessment in cognitive performance. The growing demand for accurate and fast neuropsychological assessment shows the importance of creating a universal brief assessment tool for wider cross-cultural application

A Bayesian explanation of the 'Uncanny Valley' effect and related psychological phenomena

There are a number of psychological phenomena in which dramatic emotional responses are evoked by seemingly innocuous perceptual stimuli. A well known example is the ‘uncanny valley’ effect whereby a near human-looking artifact can trigger feelings of eeriness and repulsion. Although such phenomena are reasonably well documented, there is no quantitative explanation for the findings and no mathematical model that is capable of predicting such behavior. Here I show (using a Bayesian model of categorical perception) that differential perceptual distortion arising from stimuli containing conflicting cues can give rise to a perceptual tension at category boundaries that could account for these phenomena. The model is not only the first quantitative explanation of the uncanny valley effect, but it may also provide a mathematical explanation for a range of social situations in which conflicting cues give rise to negative, fearful or even violent reactions