939 resultados para TORSION THEORIES


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This paper presents a review on applications of four types of theories for management accounting (MA) research (contingency theory, agency theory, sociological theories and psychological theories) and comments on prospects of combining multiple theories in future MA research. Based on a review of studies that adopted the four types of theories, the authors argue that multiple theories can be applied jointly in future research to enrich our understandings on MA practices from multiple perspectives. However, theories should maintain their distinctiveness in their applications. Blending multiple theories into a single all-purpose theory can be counterproductive due to loss of explanatory power.

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This thesis investigated children's school achievement in terms of an integration of three theories of achievement motivation. The three theoretical outlooks were expectancy-value theory (EVT), implicit theories of intelligence (ITI), and flow theory (FT). The first of two studies was an exploratory investigation of the effectiveness of each theory independently and combined to predict children's achievement in four school subjects. The subject areas were maths, reading, instrumental music and sport. Participants were 84 children (40 females and 44 males) aged 9 to 10 years, one of each child's parents, and school teachers of each child in the four subject areas. All data were collected through questionnaires based on the three models. The results indicated that EVT and FT but not ITI accounted for a significant amount of the variance in children's achievement, including effects for subject area and gender. A second confirmatory study tested EVT, FT and an integrated model for the prediction of achievement in maths, reading and instrumental music. The participants were a further 141 children (74 females and 67 males) aged 10 to 11 years, and a parent and teachers of each child. Data collection using questionnaires occurred early in the school year (Timel) and approximately five months later (Time2). For EVT, children and parents’ competence beliefs were significant predictors of children's achievement in each subject area. Females tended to believe themselves more competent at reading and instrumental music and also valued these subjects more highly than boys. Modeling results for flow theory indicated that children's emotional responses to classes (happiness and confusion) were significant predictors of achievement, the type of emotion varying between subject areas and time periods. Females generally had a more positive emotional reaction to reading and instrumental music classes than males did. The integrated model results indicated significant relationships between EVT and flow theories for each subject area, with EVT explaining most achievement variance in the integrated model. Children's and parents’ competence beliefs were the main predictors of achievement at Timel and 2, Subject area and gender differences were found which provide direction for future research. Anecdotal reports of parents and teachers often attest to individual differences in children's involvement in various school domains. Even among children of apparently similar intelligence, it is not uncommon to find one who likes nothing better than to work on a mathematics problem while another much prefers to read a novel or play a musical instrument Some children appear to achieve good results for most of the activities in which they are engaged while others achieve in a less consistent manner, sometimes particularly excelling in one activity. Some children respond to failure experiences with a determination to improve their performance in the future while others react with resignation and acceptance of their low ability. Some children appear to become totally absorbed in the activity of playing sport while others cannot wait for the game to end. The primary research objective guiding the current thesis is how children's thoughts and feelings about school subjects differ and are related to their school achievement. A perusal of the achievement motivation literature indicates several possible models and concepts that can be applied to explain individual differences in children's school achievement. Concepts such as academic self-concept, multiple intelligences, intrinsic and extrinsic motivation, self-beliefs, competence beliefs, subjective task values, mastery and performance goals, ‘Flow’ experiences and social motivation are just some of the constructs used to explain children's achievement motivation, both within and between various activity domains. These constructs are proposed by researchers from different theoretical perspectives to achievement motivation. Although there is much literature relevant to each perspective, there is little research indicating how the various perspectives may relate to each other. The current thesis will begin by reviewing three currently popular theoretical orientations cited in achievement motivation research: subjective beliefs and values; implicit theories of intelligence, and flow experience and family complexity. Following this review, a framework will be proposed for testing the determinants of children's school achievement, both within each of the three theoretical perspectives and also in combination.

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The aim of the present work was to undertake a detailed investigation of the softening mechanisms during hot deformation of a 21Cr-10Ni-3Mo (steel A) and a 21Cr-8Ni-3Mo (steel B) austenite/ferrite duplex stainless steels containing about 60% and 30% of austenite, respectively. The steels were subjected to hot deformation in torsion performed at 900 ºC and 1200 ºC using a strain rate of 0.7 s-1 to several strain levels. Quantitative optical and transmission electron microscopy were used in the investigation. Austenite was observed to soften via dynamic recovery (DRV) and dynamic recrystallisation (DRX) accompanied by DRV for the deformation temperatures of 900 °C and 1200 °C, respectively, for the both steels studied. DRX of austenite largely occurred through strain-induced grain boundary migration, complemented by (multiple) twinning, and developed significantly faster in steel A than in steel B, indicating that considerably larger strains partitioned into austenite in the former steel during deformation at 1200 °C. The above softening mechanism was accompanied by the formation of DRX grains from subgrains along the austenite/ferrite interface and by large-scale subgrain coalescence. At 900°C, stressassisted phase transitions between austenite and ferrite were observed, characterised by dissolution of the primary austenite, formation of Widmanstätten secondary austenite and gradual globularisation of the microstructure with increasing strain. These processes appeared to be significantly more widespread in steel B. The softening mechanism within ferrite for the both steels studied was classified as “continuous DRX”, characterised by a gradual increase in misorientations between neighbouring subgrains with strain, for the both deformation temperatures.

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The effects of strain path reversal on the macroscopic orientation of microbands in AA5052 have been studied using high resolution electron backscatter diffraction. Deformation was carried using two equal steps of forward/forward or forward/reverse torsion at a temperature of 300°C and strain rate of 1s-1 to a total equivalent tensile strain of 0.5. In both cases microbands were found in the majority of grains examined with many having more than one set. The microbands appear to cluster at specific angles to the macroscopic deformation. For the forward/forward condition microbands clustered around -20° and +45° to the maximum principle stress direction and at ± 30-35° to the principal strain direction. For the forward/reverse condition significantly more spread in microband angle was observed though peaks were visible at ±35° with respect to principal stress direction and at -40° and +30° with respect to the principal strain direction of the reverse torsion. This suggests the microbands formed in the forward deformation have or are dissolving and any new microbands formed are related to the deformation conditions of the final strain path.

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Interdisciplinary teaching and learning in higher education incorporates multiple ways of knowing. As interdisciplinary pedagogies become increasingly important in a global knowledge economy, which learning theories best inform thinking and practice in these endeavours? This paper explores a range of theories and ideas about learning, including constructivism, situated learning, experiential learning and phenomenography, and their relevance to interdisciplinarity in higher education.

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A comprehensive introduction to the most widely used approach to social work theory and practice. It offers a systematic overview of core theories and practice issues in challenging domination and oppression.

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The Ottawa Charter laid the ground work for a new research and practice agenda by urging health promoters to advocate for healthy public policies. After more than 20 years, it is now time to reflect on the state of policy research in health promotion and to examine how rigorously theories are applied. The review of the literature was
conducted on 11 peer-reviewed journals. The journals were selected for their solid track record in publishing health promotion articles and by using a set of predefined
inclusion and exclusion criteria. The articles, published between January 1986 and June 2006, were searched using Medline and CINAHL databases. The selected papers feature search terms related to ‘politics’, ‘policy’, ‘advocacy’ and ‘coalition’. We examined the theoretical grounding of each paper and whether it focuses on policy content (e.g. nature, impact, evolution of the policy), policy processes (e.g. advocacy capacity building and strategies) or theoretical/methodological issues in policy analysis. This review demonstrates that policy research in health promotion is still largely an a theoretical enterprise. Out of the 119 articles that were found eligible, 39 did apply to some degree a theoretical framework, of which 21 referred to a theoretical framework from political science. We conclude that the field has yet to acknowledge critical concepts that would help to shed light on the policy process, and that validated rigorous theoretical frameworks to inform research and practice are hardly applied. Recommendations are formulated to improve policy research in health promotion.