Describing the plastic deformation of aluminium softball bats

Hollow aluminium bats were introduced over 30 years ago to provide improved durability over wooden bats. Since their introduction, however, interest in hollow bats has focused almost exclusively around their hitting performance. The aim of this study was to take advantage of the progress that has been made in predicting bat performance using finite elements and apply it to describe bat durability. Accordingly, the plastic deformation from a ball impact of a single-wall aluminum bat was numerically modelled. The bat deformation from the finite-element analysis was then compared with experiment using a high-speed bat test machine. The ball was modelled as an isotropic, homogeneous, viscoelastic sphere. The viscoelastic parameters of the ball model were found from instrumented, high-speed, rigid-wall ball impacts. The rigid-wall ball impacts were modelled numerically and showed good agreement with the experimentally obtained response. The strain response of the combined bat-ball model was verified with a strain-gauged bat at intermediate ball impact speeds in the elastic range. The strain response of the bat-ball model exhibited positive correlation with the experimental measurements. High-speed bat-ball impacts were performed experimentally and simulated numerically at increasing impact speeds which induced correspondingly increased dent sizes in the bat. The plastic deformation from the numerical model found good agreement with experiment provided the aluminium work hardening and strain rate effects were appropriately described. The inclusion of strain rate effects was shown to have a significant effect on the bat deformations produced in the finite-element simulations. They also helped explain the existence of high bat stresses found in many performance models.     

'It was Better than Sitting in a Group and Talking'. An Evaluation of a Film-Making Project with Young People in Trouble or 'At Risk' in School

This paper will explore some issues raised by an evaluation of a Scottish video making project which works with young people in trouble or 'at risk' in school. In the paper we reflect on the problems of evaluating work with troubled and troublesome pupils and on the difficulties of both collecting and presenting appropriate evidence. It offers a contribution to continuing debates over educational exclusion and inclusion and to the research literature on strategies for supporting young people in school. The paper also raises key questions about the planning and evaluating of support services for young people by schools.     

Who Studies Women's Studies?

ABSTRACT This article reports the initial findings of a study of the cohort of students who entered Liverpool John Moores University, England, to study women's studies in the autumn of 1994, basing its focus on the survey carried out as soon as the students entered the University and the in-depth interviews carried out later in that semester. The work proceeded within the tradition of grounded theory research and endeavoured to avoid prepared hypotheses in order to allow the themes to emerge from the students' answers. From the initial findings, the very strong emphasis on the salience of the students' choice of women's studies and the experiential importance of identity as a concept was striking. The article debates the theoretical difficulties in the theorising of identity in relation to the empirical, existential project of the students.     

Language and reading impairments are associated with increased prevalence of non-right-handedness

Handedness has been studied for association with language-related disorders because of its link with language hemispheric dominance. No clear pattern has emerged, possibly because of small samples, publication bias, and heterogeneous criteria across studies. Non-right-handedness (NRH) frequency was assessed in N = 2503 cases with reading and/or language impairment and N = 4316 sex-matched controls identified from 10 distinct cohorts (age range 6–19 years old; European ethnicity) using a priori set criteria. A meta-analysis (N_cases = 1994) showed elevated NRH % in individuals with language/reading impairment compared with controls (OR = 1.21, CI = 1.06–1.39, p = .01). The association between reading/language impairments and NRH could result from shared pathways underlying brain lateralization, handedness, and cognitive functions.     

Field and laboratory measurements of softball player swing speed and bat performance

The swing speed of the bat is one of the most important factors affecting the hit-ball speed. Most field studies tend to focus on measuring ball speed, which is easier to measure and quantify than bat speed. For this reason, relatively little data exist describing bat motion in field conditions. The following describes a relatively large swing speed field study involving bats of the same model with nearly constant weight and varying inertia. The study was conducted using right-handed batters on a regulation outdoor field with a live pitcher. Swing speed was measured by tracking markers on the bat with two high-speed video cameras so that the bat markers could be traced in three-dimensional space. The ball motion was tracked using the same high-speed video cameras and a three-dimensional Doppler radar system. Bat swing speed was observed to be proportional to the batter skill level and the normalised swing speed increased with decreasing bat inertia. The bat centre of rotation during impact was close to the knob of the bat. The bats were tested under controlled laboratory conditions using a standardised performance test. The field and laboratory results showed good agreement including the hit-ball speed and the subtle effect of bat inertia on the maximum performance location. The vibrational response of the bats was considered using modal analysis. The maximum performance location was correlated with the node of the first vibrational mode.     

Understanding students’ experiences of professionalism learning: a ‘threshold’ approach

Professionalism is a core element of curricula in many disciplines but can be difficult to teach and learn. This study used audio-diary methodology to identify professionalism threshold concepts in a small group learning setting in undergraduate medicine and to understand factors that might facilitate students to ‘get’ such concepts. Fifteen students and seven tutors kept audio-diaries over two terms. Data were analysed qualitatively for content. The key themes were then cross referenced to threshold concept criteria (e.g. where language indicated that learning was troublesome, integrative or transformative). Seven potential threshold concepts were identified which centred on students’ developing professional identities including working with uncertainty, considering the bigger picture, not needing to know everything and professional culture. Reflection on workplace experiences within a small group helped students ‘get’ these concepts. The study concludes that threshold concepts and audio-diaries are useful tools for understanding lived experiences of professionalism learning.