Modeling of advanced high strength steels with the realistic microstructure–strength relationships

The objective of the work is to consider the first-order effects of the realistic microstructure morphology in the macroscale modeling of the multiphase Advanced High Strength Steels (AHSS). Instead of using constitutive equations at macroscale, the strength–microstructure relationship is studied in the forms of micromechanical and multiscale models that do not make considerable simplifications with regard to the microscale geometry and topology. The trade-off between the higher computational time and the higher accuracy has been offset with a stochastic approach in the construction of the microscale models. The multiphase composite effects of AHSS microstructure is considered in realistic microstructural models that are stochastically built from AHSS micrographs. Computational homogenization routines are used to couple micro and macroscale and resultant stress–strain relations are compared for models built with the simplified and idealized geometries of the microstructure. The results from this study show that using a realistic representation of the microstructure, either for DP or TRIP steel, could improve the accuracy of the predicted stress and strain distribution. The resultant globally averaged effective stress and strain fields from realistic microstructure model were able to accurately capture the onset of the plastic instability in the DP steel. It is shown that the macroscale mechanical behavior is directly affected by the level of complexities in the microscale models. Therefore, greater accuracy could be achieved if these stochastic realistic microstructures are used at the microscale models.

A full body musculoskeletal model based on flexible multibody simulation approach utilised in bone strain analysis during human locomotion

Load-induced strains applied to bone can stimulate its development and adaptation. In order to quantify the incident strains within the skeleton, in vivo implementation of strain gauges on the surfaces of bone is typically used. However, in vivo strain measurements require invasive methodology that is challenging and limited to certain regions of superficial bones only such as the anterior surface of the tibia. Based on our previous study [Al Nazer et al. (2008) J Biomech. 41:1036–1043], an alternative numerical approach to analyse in vivo strains based on the flexible multibody simulation approach was proposed. The purpose of this study was to extend the idea of using the flexible multibody approach in the analysis of bone strains during physical activity through integrating the magnetic resonance imaging (MRI) technique within the framework. In order to investigate the reliability and validity of the proposed approach, a three-dimensional full body musculoskeletal model with a flexible tibia was used as a demonstration example. The model was used in a forward dynamics simulation in order to predict the tibial strains during walking on a level exercise. The flexible tibial model was developed using the actual geometry of human tibia, which was obtained from three-dimensional reconstruction of MRI. Motion capture data obtained from walking at constant velocity were used to drive the model during the inverse dynamics simulation in order to teach the muscles to reproduce the motion in the forward dynamics simulation. Based on the agreement between the literature-based in vivo strain measurements and the simulated strain results, it can be concluded that the flexible multibody approach enables reasonable predictions of bone strain in response to dynamic loading. The information obtained from the present approach can be useful in clinical applications including devising exercises to prevent bone fragility or to accelerate fracture healing.

A validity-driven approach to the understanding of the personal and societal burden of low back pain : development of a conceptual and measurement model

Introduction: While the importance and magnitude of the burden of low back pain upon the individual is well recognized, a systematic understanding of the impact of the condition on individuals is currently hampered by the lack of an organized understanding of what aspects of a person’s life are affected and the lack of comprehensive measures for these effects. The aim of the present study was to develop a conceptual and measurement model of the overall burden of low back pain from the individual’s perspective using a validity-driven approach.
Methods: To define the breadth of low back pain burden we conducted three concept-mapping workshops to generate an item pool. Two face-to-face workshops (Australia) were conducted with people with low back pain and clinicians and policy-makers, respectively. A third workshop (USA) was held with international multidisciplinary experts. Multidimensional scaling, cluster analysis, participant input and thematic analyses organized participants’ ideas into clusters of ideas that then informed the conceptual model.
Results: One hundred and ninety-nine statements were generated. Considerable overlap was observed between groups, and four major clusters were observed - Psychosocial, Physical, Treatment and Employment - each with between two and six subclusters. Content analysis revealed that elements of the Psychosocial cluster were sufficiently distinct to be split into Psychological and Social, and a further cluster of elements termed Positive Effects also emerged. Finally, a hypothesized structure was proposed with six domains and 16 subdomains. New domains not previously considered in the back pain field emerged for psychometric verification: loss of independence, worry about the future, and negative or discriminatory actions by others.
Conclusions: Using a grounded approach, an explicit a priori and testable model of the overall burden of low back pain has been proposed that captures the full breadth of the burden experienced by patients and observed by experts.

A marginalised Markov Chain Monte Carlo approach for model based analysis of EEG data

The work presented in this paper focuses on fitting of a neural mass model to EEG data. Neurophysiology inspired mathematical models were developed for simulating brain's electrical activity imaged through Electroencephalography (EEG) more than three decades ago. At the present well informative models which even describe the functional integration of cortical regions also exists. However, a very limited amount of work is reported in literature on the subject of model fitting to actual EEG data. Here, we present a Bayesian approach for parameter estimation of the EEG model via a marginalized Markov Chain Monte Carlo (MCMC) approach.

CADET - Centre for Advanced Design in Engineering Training

BACKGROUND : The Centre for Advanced Design in Engineering Training (CADET) is a partnership of Deakin University and the Gordon Institute of TAFE that will improve access and pathways into careers to address Australia’s critical engineering skills shortage (Walton, C). Local high schools, Belmont High and Matthew Flinders Girls Secondary College are included as strategic partners. CADET is proposed to be a teaching and learning facility providing a project focused modern engineering approach to students at regional schools and TAFE as well as Deakin’s degree programs. CADET will emphasize engineering design and development through virtual and physical modelling, simulation and prototyping – skills at the heart of the 21st century engineering challenges, and will serve as an attractor to engineering and related professions.

PURPOSE : The purpose of this paper is to present an argument toward the development of a Centre for advanced design in engineering training. CADET is proposed to increase the awareness and attractiveness of engineering as an education and career option, particularly for women, in regional schools, provide under one roof state-of-the-art engineering design, modelling and prototyping facilities, facilitate access and articulation pathways between school, VET and Higher Education, increase the physical capacity to serve student demand in western Victoria, and reinvigorate engineering as an essential component of a skilled regional economy.

DESIGN/METHOD : The evidenced based argument towards the proposed centre for advanced design in engineering training is based on a detailed literature review as well as a research study with industry representatives in engineering design. The learning principles of the model are also investigated and aligned to the proposed centre.

RESULTS : CADET is a change to the way engineering has traditionally been taught. The outcomes of CADET will be to provide a broad range of contemporary/relevant teaching programs, improve the social benefits gained from teaching programs, improve retention rates, advance partnerships that link with rural and regional victoria, and collaborate with local communities to encourage governments to support regional capacity building. Through focus group interviews and open discussions with industry and academia over the past 12 months on the integration of design skills in engineering education, results indicate that the following key skills are essential elements required for a successful project oriented design based learning curriculum are creative & innovative skills, successful industry engagement, and awareness of design skills in early years. Feedback also showed that 80% of the industry representatives are looking to recruit graduates who acquired design-equipped skill and 60% indicated that they want graduates who acquired knowledge through projects.

CONCLUSIONS : CADET projected benefits are significant at the strategic and operational levels. They include access for more women in engineering, facilitates articulation pathways between VET and HE, targeted recognised critical current engineering skills shortage in Australia, improvement of regional access, attractiveness and participation in tertiary education, achievement of a significant improvement in the teaching-research nexus.

A fractional cointegration approach to testing the Ohlson accounting based valuation model

We examine the long-run relationship between market value, book value, and residual income in the Ohlson (Contemp Acc Res 11(2):661-687, 1995) model. In particular, we test if market value is cointegrated with book value and residual income in light of their non-stationary behaviors. We find that cointegration applies to only 51 % of the sample firms, casting doubt that book value and residual income alone are adequate in tracking variations in market value, yet we find that market value is fractional cointegrated with book value and residual income for 89 % of the sample firms. This implies that the long-run relationship follows a slow but mean-reverting process. Our results therefore support the Ohlson model. © 2012 Springer Science+Business Media New York.

Understanding the link between body image and binge eating: a model comparison approach

Purpose
The present study tests several competing, explanatory models—dual pathways, escape from awareness, and objectification theory—for the established link between body dissatisfaction and binge eating.

Methods
408 women aged between 18 and 40 years completed a survey designed to assess contributions of proposed mediators (dietary restraint and negative affect from the dual pathway model, self-distraction from the escape from awareness model, and interoceptive deficits from objectification theory) for the body dissatisfaction–binge eating relationship.

Results
Although mediation analyses supported the dual pathway model and objectification theory when tested separately, the dual pathway model most strongly predicted the body dissatisfaction–binge eating relationship. Both model-implied mediators (dietary restraint and negative affect) made significant unique contributions, accounting for roughly one-quarter of the shared variance between body dissatisfaction and binge eating when tested separately from other mediators. Improvements in variance explained were negligible once other proposed mediators were included in a test of models combined.

Conclusions
Collectively, these findings suggest the superiority of the dual pathway model over objectification theory and the escape model, but the remaining unaccounted for covariance suggests need to consider alternative mechanisms that may also account for the relationship between body dissatisfaction and binge eating.