18 resultados para Structural investigation

em Deakin Research Online - Australia


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This paper considers the delivery and assessment strategies used in two structural mechanics units at Deakin University, a leader in distance education in Australia. The two units have had unacceptably high rates of student failure. Student perceptions of the delivery method were analysed and an investigation was carried out of the performance of 329 (173 on- and 156 off-campus) students enrolled in the two units. An analysis of the assignment, laboratory and examination marks is presented. Consideration is also given to the total marks. The results show that on-campus students performed better in structural mechanics than their off-campus counterparts. Plots of the distributions of student performance for the three assessment methods are provided (for each unit) and high failure rates are linked to low examination marks. Students tended to perform best in assignments and worst in examinations. Parametric statistical tests show a correlation between the marks obtained in continuous assessment and in examinations, and it is therefore proposed that, in order to improve performance, the students must be encouraged to participate fully in all aspects of the course. Many students were unenthusiastic about laboratory practical sessions and did not think they aided their understanding of the theoretical material. Motivation to participate is often dependent on the perceived relevance of a given task and its contribution to the total mark and, thus, to help motivate students to participate fully in the continuous assessment tasks, the authors propose several changes to the delivery methods, as well as to assessment criteria and marking schemes.

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The role of marketing employees in contributing to marketing performance (individual and organisational), has, in general, been under-researched. Most research in marketing has focused on the activities of marketing employees and the outputs of those activities, rather than the inputs, i.e., the abilities, skills, or knowledge of the marketing employees themselves. This study represents a unique insight into the marketing capabilities and marketing performance of employees within a multinational organisation, as reported by the employees themselves. Using Structural Equation Modelling (SEM), strong support was found for a systems model of marketing competency marketing performance, suggesting that such relationships are complex and are not studied readily in isolation from external factors. Organisations that are able to conceptualise, operationalise, measure, monitor, and address marketing employee competency, intentions, and perceptions, as well as maintain the appropriate levels of management control, should have a greater likelihood of creating high performing employees, than those organisations that are unable to focus on these core aspects of people's performance. In addition, those same employees are likely to be more satisfied, motivated, and committed, require less assistance and time to complete tasks, and have greater productivity and be less likely to leave the orga.'1isation.

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Purpose – The purpose of the study is to examine the influence of multiple factors on the green purchase intention of customers in Australia.

Design/methodology/approach – A conceptual model is proposed and was subjected to empirical verification with the use of a survey of metropolitan and regional households in Victoria, Australia. The data were analyzed using both descriptive measures and exploratory factor analysis to identify and validate the items contributing to each component in the model. AMOS structural modeling was used to estimate the measure of respondents' overall perception of green products and their intention to purchase.

Findings – The results indicate that customers' corporate perception with respect to companies placing higher priority on profitability than on reducing pollution and regulatory protection were the significant predictors of customers' negative overall perception toward green products. The only positive contribution to customers' perception was their past experience with the product. Other factors including the perception of green products, product labels, packaging, and product ingredients did not appear to influence customers' perception. The results also indicate that customers are not tolerant of lower quality and higher prices of green products.

Research limitations/implications – The knowledge of the overall perception formation about green products and its predictors provides management with the facility to identify and implement strategies that may better influence the change of attitude by customers. Corporations can also benefit from the identification of the types of information required to enable management to influence this process of perception formation.

Originality/value – The present findings contributes to an understanding of the antecedents of green purchasing and highlight that green customers rely more on personal experience with the product than the information provided by the marketer.

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Tube hydroforming has been widely used to produce automotive structural components due to the superior properties of the hydroformed parts in terms of their light weight and structural rigidity. Compared to the traditional manufacturing process for a closed-section member including stamping and followed by welding, tube-hydro forming leads to cost savings due to reduced tooling and material handling. However, the high pressure pumps and high tonnage press required in hydroforming, lead to increased capital investment reducing the cost benefits. This study explores low pressure tube hydro forming which reduces the internal fluid pressure and die closing force required to produce the hydroformed part. The experimental and numerical analysis was for low pressure hydro formed stainless steel tubes. Die filling conditions and thickness distributions are measured and critically analysed.

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In Canada there are numerous studies about indigenous Entrepreneurship, most descriptive with little theory development or testing, This leaves a gap in the information available to researchers, policy makers and practitioners. In this paper we describe a research program intended to address this gap beginning with the activities of the Lac La Ronge Indian Band, considered an exemplar of successful indigenous entrepreneurship. From these activities, we draw propositions about indigenous entrepreneurship that are compatible with generic theory. Finally, we describe how we will move from these propositions to a model of indigenous entrepreneurship using grounded theory and structural equation modelling.

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Information technology research over the past two decades suggests that the installation and use of computers fundamentally affects the structure and function of organisations and, m particular, the workers in these organizations. Following the release of the IBM Personal Computer in 1982, microcomputers have become an integral part of most work environments. The accounting services industry, in particular, has felt the impact of this ‘microcomputer revolution’. In Big Six accounting firms, there is almost one microcomputer for each professional accountant employed, Notwithstanding this, little research has been done on the effect of microcomputers on the work outcomes of professional accountants working in these firms. This study addresses this issue. It assesses, in an organisational setting, how accountant’ perceptions of ease of use and usefulness of microcomputers act on their computer anxieties, microcomputer attitudes and use to affect their job satisfaction and job performance. The research also examines how different types of human-computer interfaces affect the relationships between accountants' beliefs about microcomputer utility and ease of use, computer anxiety, microcomputer attitudes and microcomputer use. To attain this research objective, a conceptual model was first developed, The model indicates that work outcomes (job satisfaction and job performance) of professional accountants using microcomputers are influenced by users' perceptions of ease of use and usefulness of microcomputers via paths through (a) the level of computer anxiety experienced by users, (b) the general attitude of users toward using microcomputers, and (c) the extent to which microcomputers are used by individuals. Empirically testable propositions were derived from the model to test the postulated relationships between these constructs. The study also tested whether or not users of different human-computer interfaces reacted differently to the perceptions and anxieties they hold about microcomputers and their use in the workplace. It was argued that users of graphical interfaces, because of the characteristics of those interfaces, react differently to their perceptions and anxieties about microcomputers compared with users of command-line (or textual-based) interfaces. A passive-observational study in a field setting was used to test the model and the research propositions. Data was collected from 164 professional accountants working in a Big Six accounting firm in a metropolitan city in Australia. Structural equation modelling techniques were used to test the, hypothesised causal relationships between the components comprising the general research model. Path analysis and ordinary least squares regression was used to estimate the parameters of the model and analyse the data obtained. Multisample analysis (or stacked model analysis) using EQS was used to test the fit of the model to the data of the different human-computer interface groups and to estimate the parameters for the paths in those different groups. The results show that the research model is a good description of the data. The job satisfaction of professional accountants is directly affected by their attitude toward using microcomputers and by microcomputer use itself. However, job performance appears to be only directly affected by microcomputer attitudes. Microcomputer use does not directly affect job performance. Along with perceived ease of use and perceived usefulness, computer anxiety is shown to be an important determinant of attitudes toward using microcomputers - higher levels of computer anxiety negatively affect attitudes toward using microcomputers. Conversely, higher levels of perceived ease of use and perceived usefulness heighten individuals' positive attitudes toward using microcomputers. Perceived ease of use and perceived usefulness also indirectly affect microcomputer attitudes through their effect on computer anxiety. The results show that higher levels of perceived ease of use and perceived usefulness result in lower levels of computer anxiety. A surprising result from the study is that while perceived ease of use is shown to directly affect the level of microcomputer usage, perceived usefulness and attitude toward using microcomputers does not. The results of the multisample analysis confirm that the research model fits the stacked model and that the stacked model is a significantly better fit if specific parameters are allowed to vary between the two human-computer interface user groups. In general, these results confirm that an interaction exists between the type of human-computer interface (the variable providing the grouping) and the other variables in the model The results show a clear difference between the two groups in the way in which perceived ease of use and perceived usefulness affect microcomputer attitude. In the case of users of command-line interfaces, these variables appear to affect microcomputer attitude via an intervening variable, computer anxiety, whereas in the graphical interface user group the effect occurs directly. Related to this, the results show that perceived ease of use and perceived usefulness have a significant direct effect on computer anxiety in command-line interface users, but no effect at all for graphical interface users. Of the two exogenous variables only perceived ease of use, and that in the case of the command-line interface users, has a direct significant effect on extent of use of microcomputers. In summary, the research has contributed to the development of a theory of individual adjustment to information technology in the workplace. It identifies certain perceptions, anxieties and attitudes about microcomputers and shows how they may affect work outcomes such as job satisfaction and job performance. It also shows that microcomputer-interface types have a differential effect on some of the hypothesised relationships represented in the general model. Future replication studies could sample a broader cross-section of the microcomputer user community. Finally, the results should help Big Six accounting firms to maximise the benefits of microcomputer use by making them aware of how working with microcomputers affects job satisfaction and job performance.

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This thesis examined body dissatisfaction and body change behaviors among adolescent girls and boys from a biopsychosocial framework. The contribution of biological, psychological and sociocultural factors were examined in relation to body dissatisfaction, weight loss, weight gain and increased muscle tone behaviors among early adolescent girls and boys. In particular, pubertal maturation, body mass index (BMI), perception of body shape and size and psychological factors, such as depression, anxiety, ineffectiveness, self-esteem and perfectionism, were examined as possible factors that may precipitate or maintain body dissatisfaction and engagement in body change strategies. The sociocultural factors evaluated were the quality of family and peer relationships, as well as the influence of family and peers in predicting the adoption of specific body change strategies. The specific mechanisms by which these influences were transmitted were also examined. These included perceived discussion, encouragement and modelling of various body change strategies, as well as perceived teasing about body shape and size. A number of separate cross-sectional and longitudinal studies were conducted to examine the above relationships and identify the factors that contribute to weight loss, weight gain and increased muscle tone behaviors in adolescents. Study 1 examined the psychometric properties and principal components structure of the Bulimia Test Revised (BULIT-R; Thelen, Farmer, Wonderlich, & Smith, 1991) to assess its applicability to adolescent samples. Study 2 investigated the nature of body dissatisfaction and weight loss behaviors among 603 adolescents (306 girls and 297 boys) using a standardised questionnaire. This preliminary study was conducted to ascertain whether variables previously found to be relevant to adolescent girls, could also be related to the development of body dissatisfaction and weight loss behaviors among adolescent boys. Studies 3 and 4 described the development and validation of a body modification scale that measured weight loss, weight gain and increased muscle tone behaviors. Studies 5 and 6 were designed to modify an Excessive Exercise Scale developed by Long, Smith, Midgley, and Cassidy (1993) into a shorter form, and validate this scale with an adolescent sample. Study 7 investigated the factors that contribute to weight loss, weight gain and increased muscle among adolescent girls and boys both cross-sectionally and longitudinally (over one year). Structural equation modelling was used to examine associations among self-reported body dissatisfaction, body change strategies and a range of biological, psychological and sociocultural variables both cross-sectionally and longitudinally. Overall, the results suggested that both girls and boys experience body dissatisfaction and engage in a number of different body change strategies in order to achieve an ideal size. A number of gender similarities and differences were identified in the expression of body dissatisfaction and the adoption of body change strategies for both girls and boys. Girls were more likely than boys to report body dissatisfaction and engage in weight loss behaviors, while boys were more likely than girls to engage in weight gain and increased muscle tone behaviors. Generally, the same factors were found to contribute to weight loss, and more specifically, bulimic symptomatology, ad weight gain in both adolescent girls and boys. While a combination of biological, psychological and sociocultural factors contributed to bulimic symptomatology, only biological and psychological factors were found to contribute to weight gain in adolescents. The most notable gender differences were found in the model of increased muscle tone. Sociocultural and biological factors contributed to increased muscle tone behaviors in girls, while sociocultural and psychological factors were implicated in these behaviors in adolescent boys. With the exception of the model of increased muscle tone for boys, body dissatisfaction was a consistent factor in the adoption of body change behaviors. Consistent with previous investigations, the present thesis provides empirical support for the need to examine the etiology and maintenance of such concerns and behaviors from a multifaceted perspective.

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Hollow structures made of Advanced High Strength Steel (AHSS) are increasingly used in the automobile industry for crash and structural components. Generally high pressure hydroforming is used to form these tabular parts, which is a costly manufacturing process due to the high pressure equipment and large tonnage presses required. A new process termed low pressure hydroforming, where a pressurized tube is crushed between two dies, represents a more cost effective alternative due to the lower pressures and die closing forces required.

In this study the low pressure tube hydroforming of one simple and two different complex hollow shapes is investigated. The complexities of the pat1S compared to simple shapes are critically studied and the die filling conditions are investigated and discussed. FUl1hennore the thickness distributions over the circumference of the part during forming are analyzed.

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Choline dihydrogen phosphate has previously been shown to be a good ionic conductor as well as an excellent host for acid doping, leading to high proton conductivities required for e.g., electrochemical devices including proton membrane fuel cells and sensors. A combination of variable-temperature 1H solid-state NMR and 2D NMR pulse sequences, including 31P and 13C CODEX and 1H BaBa, show that the proton conduction mechanism primarily involves assisted transport via a restricted three-site motion of the phosphate unit around the P–O bond that is hydrogen bonded to the choline and exchange of protons between these anions. In other words, proton transport at ambient temperatures appears to occur most favorably along the crystallographic b axis, from phosphate dimer to dimer. At elevated temperatures exchange between the protons of the hydroxyl group on the choline cation and the hydrogen-bonded dihydrogen phosphate groups also contributes to the structural diffusion of the protons in this solid state conductor.

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Silk is a structural protein fiber that is stable over a wide pH range making it attractive for use in medical and environmental applications. Variation in amino acid composition has the potential for selective binding for ions under varying conditions. Here we report on the metal ion separation potential of Mulberry and Eri silk fibers and powders over a range of pH. Highly sensitive radiotracer probes, 64Cu2+, 109Cd2+, and 57Co2+ were used to study the absorption of their respective stable metal ions Cu2+, Cd2+, and Co2+ into and from the silk sorbents. The total amount of each metal ion absorbed and time taken to reach equilibrium occurred in the following order: Cu2+ > Cd2+ > Co 2+. In all cases the silk powders absorbed metal ions faster than their respective silk fibers. Intensive degumming of the fibers and powders significantly reduced the time to absorb respective metal ions and the time to reach equilibrium was reduced from hours to 5-15 min at pH 8. Once bound, 45-100% of the metal ions were released from the sorbents after exposure to pH 3 buffer for 30 min. The transition metal ion loading capacity for the silk sorbents was considerably higher than that found for commercial ion exchange resins (AG MP-50 and AG 50W-X2) under similar conditions. Interestingly, total Cu2+ bound was found to be higher than theoretically predicted values based on known specific Cu2+ binding sites (AHGGYSGY), suggesting that additional (new) sites for transition metal ion binding sites are present in silk fibers.

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Coloured conducting textiles have shown a wide range of potential applications in heating fabrics, electromagnetic wave absorption, and wearable optoelectronic devices. This research aimed at clarifying some issues occurred in the research project on coloured conductive textiles. The investigation firstly clarified a possible chemical reaction that took place between a commercial dispersing dye (Terasil Red G) and the conducting polymer polypyrrole, through chemical separation, structural identification and spectrum characterisations. Then, a series of acidic dyes were introduced into polypyrrole matrix during the vapour coating of conducting polymer on the wool fabrics. Colour and thermal stability studies were conducted. Finally, the polypyrrole nanoparticles (particle size several~200nm) were prepared by a microemulsion polymerisation technique. An acid dye was used as the dopant to re-dope the nanoparticles. The effect of the acidic dye on the optical absorption of nanoparticles was studied. Applying the conducting nanoparticles on wool fabrics may open an alternative path to achieve the coloured conducting textiles.

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Summary This qualitative study explored beliefs and attitudes regarding osteoporosis and its management. General medical practitioners (GPs) were ambivalent about osteoporosis due to concern about financial barriers for patients and their own beliefs about the salience of osteoporosis. GPs considered investigation and treatment in the context of patients' whole lives.

Purpose We aimed to investigate barriers, enablers, and other factors influencing the investigation and management of osteoporosis using a qualitative approach. This paper analyses data from discussions with general medical practitioners (GPs) about their beliefs and attitudes regarding osteoporosis and its management.

Methods Fourteen GPs and two practice nurses aged 27–89 years participated in four focus groups, from June 2010 to March 2011. Each group comprised 3–5 participants, and discussions were semi-structured, according to the protocol developed for the main study. Discussion points ranged from the circumstances under which GPs would initiate investigation for osteoporosis and their subsequent actions to their views about treatment efficacy and patient adherence to prescribed treatment. Audio recordings were transcribed and coded for analysis using analytic comparison to identify the major themes.

Results The GPs were not particularly concerned about osteoporosis in their patients or the general population, ranking diabetes, osteoarthritis, cardiovascular disease, and hypertension higher than concern about osteoporosis. They expressed confidence in the efficacy of anti-fracture medications but were concerned about the potential financial burden on patients with limited incomes. The GPs were unsure about guidelines for investigation and management of osteoporosis in men and the appropriate duration of treatment, particularly for the bisphosphonates in all patients.

Conclusions The GPs' ambivalence about osteoporosis appeared to stem from structural factors such as financial barriers for patients and their own beliefs about the salience of osteoporosis. GPs considered the impact of investigating and prescribing treatment in the context of patients' whole lives.

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Dynamic treatment regimes are set rules for sequential decision making based on patient covariate history. Observational studies are well suited for the investigation of the effects of dynamic treatment regimes because of the variability in treatment decisions found in them. This variability exists because different physicians make different decisions in the face of similar patient histories. In this article we describe an approach to estimate the optimal dynamic treatment regime among a set of enforceable regimes. This set is comprised by regimes defined by simple rules based on a subset of past information. The regimes in the set are indexed by a Euclidean vector. The optimal regime is the one that maximizes the expected counterfactual utility over all regimes in the set. We discuss assumptions under which it is possible to identify the optimal regime from observational longitudinal data. Murphy et al. (2001) developed efficient augmented inverse probability weighted estimators of the expected utility of one fixed regime. Our methods are based on an extension of the marginal structural mean model of Robins (1998, 1999) which incorporate the estimation ideas of Murphy et al. (2001). Our models, which we call dynamic regime marginal structural mean models, are specially suitable for estimating the optimal treatment regime in a moderately small class of enforceable regimes of interest. We consider both parametric and semiparametric dynamic regime marginal structural models. We discuss locally efficient, double-robust estimation of the model parameters and of the index of the optimal treatment regime in the set. In a companion paper in this issue of the journal we provide proofs of the main results.

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Objectives: To (a) assess the statistical power of nursing research to detect small, medium, and large effect sizes; (b) estimate the experiment-wise Type I error rate in these studies; and (c) assess the extent to which (i) a priori power analyses, (ii) effect sizes (and interpretations thereof), and (iii) confidence intervals were reported. Design: Statistical review. Data sources: Papers published in the 2011 volumes of the 10 highest ranked nursing journals, based on their 5-year impact factors. Review methods: Papers were assessed for statistical power, control of experiment-wise Type I error, reporting of a priori power analyses, reporting and interpretation of effect sizes, and reporting of confidence intervals. The analyses were based on 333 papers, from which 10,337 inferential statistics were identified. Results: The median power to detect small, medium, and large effect sizes was .40 (interquartile range [. IQR]. = .24-.71), .98 (IQR= .85-1.00), and 1.00 (IQR= 1.00-1.00), respectively. The median experiment-wise Type I error rate was .54 (IQR= .26-.80). A priori power analyses were reported in 28% of papers. Effect sizes were routinely reported for Spearman's rank correlations (100% of papers in which this test was used), Poisson regressions (100%), odds ratios (100%), Kendall's tau correlations (100%), Pearson's correlations (99%), logistic regressions (98%), structural equation modelling/confirmatory factor analyses/path analyses (97%), and linear regressions (83%), but were reported less often for two-proportion z tests (50%), analyses of variance/analyses of covariance/multivariate analyses of variance (18%), t tests (8%), Wilcoxon's tests (8%), Chi-squared tests (8%), and Fisher's exact tests (7%), and not reported for sign tests, Friedman's tests, McNemar's tests, multi-level models, and Kruskal-Wallis tests. Effect sizes were infrequently interpreted. Confidence intervals were reported in 28% of papers. Conclusion: The use, reporting, and interpretation of inferential statistics in nursing research need substantial improvement. Most importantly, researchers should abandon the misleading practice of interpreting the results from inferential tests based solely on whether they are statistically significant (or not) and, instead, focus on reporting and interpreting effect sizes, confidence intervals, and significance levels. Nursing researchers also need to conduct and report a priori power analyses, and to address the issue of Type I experiment-wise error inflation in their studies. © 2013 .