Numerical and experimental studies of multi-ply woven carbon fibre prepreg forming process

Woven carbon fibre prepreg is being increasingly used in high-performance aerospace and automotive applications, primarily because of its superior mechanical properties and formability. A wide range of forming simulation options are available for predicting material deformation during the prepreg forming process, particularly change in fibre orientation. Development of a robust validated simulation model requires comprehensive material characterisation and reliable experimental validation techniques. This paper presents experimental and numerical methods for studying the fibre orientation in multi-ply woven carbon fibre prepreg forming process, using a double-dome geometry. The numerical study is performed using the commercial forming simulation software PAM-FORM and the material input data are generated from a comprehensive experimental material characterisation. Two experimental validation methods are adopted for fibre shear angle measurement: an optical method for measuring only the surface plies, and a novel CT scan method for measuring both the surface plies and the internal plies. The simulation results are compared against the experimental results in terms of fibre shear angle and the formation of wrinkles to assess the validity of the model

Advanced mathematical study and the development of conditional reasoning skills

Since the time of Plato, philosophers and educational policy-makers have assumed that the study of mathematics improves one's general 'thinking skills'. Today, this argument, known as the 'Theory of Formal Discipline' is used in policy debates to prioritize mathematics in school curricula. But there is no strong research evidence which justifies it. We tested the Theory of Formal Discipline by tracking the development of conditional reasoning behavior in students studying post-compulsory mathematics compared to post-compulsory English literature. In line with the Theory of Formal Discipline, the mathematics students did develop their conditional reasoning to a greater extent than the literature students, despite them having received no explicit tuition in conditional logic. However, this development appeared to be towards the so-called defective conditional understanding, rather than the logically normative material conditional understanding. We conclude by arguing that Plato may have been correct to claim that studying advanced mathematics is associated with the development of logical reasoning skills, but that the nature of this development may be more complex than previously thought

Interventions for attentional disruption in pain: cognition-general, mechanism-specific or exercise-based?

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link

Intelligence and negation biases on the Conditional Inference task:A dual-processes analysis

This article was published in the journal Thinking and Reasoning [© Taylor and Francis]. The definitive version is available at: http://dx.doi.org/10.1080/13546783.2014.897254We examined a large set of conditional inference data compiled from several previous studies and asked three questions: How is normative performance related to intelligence? Does negative conclusion bias stem from Type 1 or Type 2 processing? Does implicit negation bias stem from Type 1 or Type 2 processing? Our analysis demonstrated that rejecting denial of the antecedent and affirmation of the consequent inferences was positively correlated with intelligence, while endorsing modus tollens inferences was not; that the occurrence of negative conclusion bias was related to the extent of Type 2 processing; and that the occurrence of implicit negation bias was not related to the extent of Type 2 processing. We conclude that negative conclusion bias is, at least in part, a product of Type 2 processing, while implicit negation bias is not

Measuring the approximate number system

Recent theories in numerical cognition propose the existence of an approximate number system (ANS) that supports the representation and processing of quantity information without symbols. It has been claimed that this system is present in infants, children, and adults, that it supports learning of symbolic mathematics, and that correctly harnessing the system during tuition will lead to educational benefits. Various experimental tasks have been used to investigate individuals' ANSs, and it has been assumed that these tasks measure the same system. We tested the relationship across six measures of the ANS. Surprisingly, despite typical performance on each task, adult participants' performances across the tasks were not correlated, and estimates of the acuity of individuals' ANSs from different tasks were unrelated. These results highlight methodological issues with tasks typically used to measure the ANS and call into question claims that individuals use a single system to complete all these tasks

Non-verbal number acuity correlates with symbolic mathematics achievement:But only in children

This article was published in the journal, Psychonomic Bulletin and Review [Springer © Psychonomic Society, Inc.]. The final publication is available at www.springerlink.com.The process by which adults develop competence in symbolic mathematics tasks is poorly understood. Nonhuman animals, human infants, and human adults all form nonverbal representations of the approximate numerosity of arrays of dots and are capable of using these representations to perform basic mathematical operations. Several researchers have speculated that individual differences in the acuity of such nonverbal number representations provide the basis for individual differences in symbolic mathematical competence. Specifically, prior research has found that 14-year-old children’s ability to rapidly compare the numerosities of two sets of colored dots is correlated with their mathematics achievements at ages 5–11. In the present study, we demonstrated that although when measured concurrently the same relationship holds in children, it does not hold in adults. We conclude that the association between nonverbal number acuity and mathematics achievement changes with age and that nonverbal number representations do not hold the key to explaining the wide variety of mathematical performance levels in adults

Relativistic parsec-scale jets: II. Synchrotron emission

We calculate the optically thin synchrotron emission of fast electrons and positrons in a spiral stationary magnetic field and a radial electric field of a rotating relativistic strongly magnetized force-free jet consisting of electron-positron pair plasma. The magnetic field has a helical structure with a uniform axial component and a toroidal component that is maximal inside the jet and decreasing to zero towards the boundary of the jet. Doppler boosting and swing of the polarization angle of synchrotron emission due to the relativistic motion of the emitting volume are calculated. The distribution of the plasma velocity in the jet is consistent with the electromagnetic field structure. Two spatial distributions of fast particles are considered: uniform, and concentrated in the vicinity of the Alfven resonance surface. The latter distribution corresponds to the regular acceleration by an electromagnetic wave in the vicinity of its Alfven resonance surface inside the jet. The polarization properties of the radiation have been obtained and compared with the existing VLBI polarization measurements of parsec-scale jets in BL Lac sources and quasars. Our results give a natural explanation of the observed bimodality in the alignment between the electric field vector of the polarized radiation and the projection of the jet axis on the plane of the sky. We interpret the motion of bright knots as a phase velocity of standing spiral eigenmodes of electromagnetic perturbations in a cylindrical jet. The degree of polarization and the velocity of the observed proper motion of bright knots depend upon the angular rotational velocity of the jet. The observed polarizations and velocities of knots indicate that the magnetic field lines are bent in the direction opposite to the direction of the jet rotation.Comment: 14 pages, 5 figures, Astron. Astroph. in pres

Support with caveats: advocates’ views of the Theory of Formal Discipline as a reason for the study of advanced mathematics

The Theory of Formal Discipline (TFD) suggests that studying mathematics improves general thinking skills. Empirical evidence for the TFD is sparse, yet it is cited in policy reports as a justification for the importance of mathematics in school curricula. The study reported in this article investigated the extent to which influential UK advocates for mathematics agree with the TFD and their views on the arguments and evidence that surround it. Quantitative and qualitative analysis of data from structured interviews revealed four themes: broad endorsement of the TFD; reference to supportive employment data; the possibilities that mathematics education might not always effectively develop reasoning and that study of other subjects might have similar effects; and concerns about causality and the extent of the evidence base. We conclude that advocates broadly support the TFD despite being aware of its limitations

Individual differences in inhibitory control, not non-verbal number acuity, correlate with mathematics achievement

Given the well-documented failings in mathematics education in many Western societies, there has been an increased interest in understanding the cognitive underpinnings of mathematical achievement. Recent research has proposed the existence of an Approximate Number System (ANS) which allows individuals to represent and manipulate non-verbal numerical information. Evidence has shown that performance on a measure of the ANS (a dot comparison task) is related to mathematics achievement, which has led researchers to suggest that the ANS plays a critical role in mathematics learning. Here we show that, rather than being driven by the nature of underlying numerical representations, this relationship may in fact be an artefact of the inhibitory control demands of some trials of the dot comparison task. This suggests that recent work basing mathematics assessments and interventions around dot comparison tasks may be inappropriate

Faraday rotation in the MOJAVE blazars: 3C 273 a case study

Radio polarimetric observations of Active Galactic Nuclei can reveal the magnetic field structure in the parsec-scale jets of these sources. We have observed the gamma-ray blazar 3C 273 as part of our multi-frequency survey with the Very Long Baseline Array to study Faraday rotation in a large sample of jets. Our observations re-confirm the transverse rotation measure gradient in 3C 273. For the first time the gradient is seen to cross zero which is further indication for a helical magnetic field and spine-sheath structure in the jet. We believe the difference to previous epochs is due to a different part of the jet being illuminated in our observations.Comment: 6 pages, 3 figures. To appear in the proceedings of "Beamed and Unbeamed Gamma-rays from Galaxies", held in Muonio, Finland, April 11-15, 2011. Journal of Physics: Conference Serie