Enhancing deep transfer learning for image classification
- Authors: Shermin, Tasfia
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Though deep learning models require a large amount of labelled training data for yielding high performance, they are applied to accomplish many computer vision tasks such as image classification. Current models also do not perform well across different domain settings such as illumination, camera angle and real-to-synthetic. Thus the models are more likely to misclassify unknown classes as known classes. These issues challenge the supervised learning paradigm of the models and encourage the study of transfer learning approaches. Transfer learning allows us to utilise the knowledge acquired from related domains to improve performance on a target domain. Existing transfer learning approaches lack proper high-level source domain feature analyses and are prone to negative transfers for not exploring proper discriminative information across domains. Current approaches also lack at discovering necessary visual-semantic linkage and has a bias towards the source domain. In this thesis, to address these issues and improve image classification performance, we make several contributions to three different deep transfer learning scenarios, i.e., the target domain has i) labelled data; no labelled data; and no visual data. Firstly, for improving inductive transfer learning for the first scenario, we analyse the importance of high-level deep features and propose utilising them in sequential transfer learning approaches and investigating the suitable conditions for optimal performance. Secondly, to improve image classification across different domains in an open set setting by reducing negative transfers (second scenario), we propose two novel architectures. The first model has an adaptive weighting module based on underlying domain distinctive information, and the second model has an information-theoretic weighting module to reduce negative transfers. Thirdly, to learn visual classifiers when no visual data is available (third scenario) and reduce source domain bias, we propose two novel models. One model has a new two-step dense attention mechanism to discover semantic attribute-guided local visual features and mutual learning loss. The other model utilises bidirectional mapping and adversarial supervision to learn the joint distribution of source-target domains simultaneously. We propose a new pointwise mutual information dependant loss in the first model and a distance-based loss in the second one for handling source domain bias. We perform extensive evaluations on benchmark datasets and demonstrate the proposed models outperform contemporary works.
- Description: Doctor of Philosophy
- Authors: Shermin, Tasfia
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Though deep learning models require a large amount of labelled training data for yielding high performance, they are applied to accomplish many computer vision tasks such as image classification. Current models also do not perform well across different domain settings such as illumination, camera angle and real-to-synthetic. Thus the models are more likely to misclassify unknown classes as known classes. These issues challenge the supervised learning paradigm of the models and encourage the study of transfer learning approaches. Transfer learning allows us to utilise the knowledge acquired from related domains to improve performance on a target domain. Existing transfer learning approaches lack proper high-level source domain feature analyses and are prone to negative transfers for not exploring proper discriminative information across domains. Current approaches also lack at discovering necessary visual-semantic linkage and has a bias towards the source domain. In this thesis, to address these issues and improve image classification performance, we make several contributions to three different deep transfer learning scenarios, i.e., the target domain has i) labelled data; no labelled data; and no visual data. Firstly, for improving inductive transfer learning for the first scenario, we analyse the importance of high-level deep features and propose utilising them in sequential transfer learning approaches and investigating the suitable conditions for optimal performance. Secondly, to improve image classification across different domains in an open set setting by reducing negative transfers (second scenario), we propose two novel architectures. The first model has an adaptive weighting module based on underlying domain distinctive information, and the second model has an information-theoretic weighting module to reduce negative transfers. Thirdly, to learn visual classifiers when no visual data is available (third scenario) and reduce source domain bias, we propose two novel models. One model has a new two-step dense attention mechanism to discover semantic attribute-guided local visual features and mutual learning loss. The other model utilises bidirectional mapping and adversarial supervision to learn the joint distribution of source-target domains simultaneously. We propose a new pointwise mutual information dependant loss in the first model and a distance-based loss in the second one for handling source domain bias. We perform extensive evaluations on benchmark datasets and demonstrate the proposed models outperform contemporary works.
- Description: Doctor of Philosophy
Enlargements of the moreau–rockafellar subdifferential
- Abbasi, Malek, Kruger, Alexander, Théra, Michel
- Authors: Abbasi, Malek , Kruger, Alexander , Théra, Michel
- Date: 2021
- Type: Text , Journal article
- Relation: Set-Valued and Variational Analysis Vol. 29, no. 3 (2021), p. 701-719
- Relation: http://purl.org/au-research/grants/arc/DP160100854
- Full Text:
- Reviewed:
- Description: This paper proposes three enlargements of the conventional Moreau–Rockafellar subdifferential: the sup-, sup
- Authors: Abbasi, Malek , Kruger, Alexander , Théra, Michel
- Date: 2021
- Type: Text , Journal article
- Relation: Set-Valued and Variational Analysis Vol. 29, no. 3 (2021), p. 701-719
- Relation: http://purl.org/au-research/grants/arc/DP160100854
- Full Text:
- Reviewed:
- Description: This paper proposes three enlargements of the conventional Moreau–Rockafellar subdifferential: the sup-, sup
Epigenome-wide association study of kidney function identifies trans-ethnic and ethnic-specific loci
- Breeze, Charles, Batorsky, Anna, Lee, Mi, Szeto, Mindy, Charchar, Fadi
- Authors: Breeze, Charles , Batorsky, Anna , Lee, Mi , Szeto, Mindy , Charchar, Fadi
- Date: 2021
- Type: Text , Journal article
- Relation: Genome Medicine Vol. 13, no. 1 (Apr 30 2021), p.
- Full Text:
- Reviewed:
- Description: Background DNA methylation (DNAm) is associated with gene regulation and estimated glomerular filtration rate (eGFR), a measure of kidney function. Decreased eGFR is more common among US Hispanics and African Americans. The causes for this are poorly understood. We aimed to identify trans-ethnic and ethnic-specific differentially methylated positions (DMPs) associated with eGFR using an agnostic, genome-wide approach. Methods The study included up to 5428 participants from multi-ethnic studies for discovery and 8109 participants for replication. We tested the associations between whole blood DNAm and eGFR using beta values from Illumina 450K or EPIC arrays. Ethnicity-stratified analyses were performed using linear mixed models adjusting for age, sex, smoking, and study-specific and technical variables. Summary results were meta-analyzed within and across ethnicities. Findings were assessed using integrative epigenomics methods and pathway analyses. Results We identified 93 DMPs associated with eGFR at an FDR of 0.05 and replicated 13 and 1 DMPs across independent samples in trans-ethnic and African American meta-analyses, respectively. The study also validated 6 previously published DMPs. Identified DMPs showed significant overlap enrichment with DNase I hypersensitive sites in kidney tissue, sites associated with the expression of proximal genes, and transcription factor motifs and pathways associated with kidney tissue and kidney development. Conclusions We uncovered trans-ethnic and ethnic-specific DMPs associated with eGFR, including DMPs enriched in regulatory elements in kidney tissue and pathways related to kidney development. These findings shed light on epigenetic mechanisms associated with kidney function, bridging the gap between population-specific eGFR-associated DNAm and tissue-specific regulatory context.
Epigenome-wide association study of kidney function identifies trans-ethnic and ethnic-specific loci
- Authors: Breeze, Charles , Batorsky, Anna , Lee, Mi , Szeto, Mindy , Charchar, Fadi
- Date: 2021
- Type: Text , Journal article
- Relation: Genome Medicine Vol. 13, no. 1 (Apr 30 2021), p.
- Full Text:
- Reviewed:
- Description: Background DNA methylation (DNAm) is associated with gene regulation and estimated glomerular filtration rate (eGFR), a measure of kidney function. Decreased eGFR is more common among US Hispanics and African Americans. The causes for this are poorly understood. We aimed to identify trans-ethnic and ethnic-specific differentially methylated positions (DMPs) associated with eGFR using an agnostic, genome-wide approach. Methods The study included up to 5428 participants from multi-ethnic studies for discovery and 8109 participants for replication. We tested the associations between whole blood DNAm and eGFR using beta values from Illumina 450K or EPIC arrays. Ethnicity-stratified analyses were performed using linear mixed models adjusting for age, sex, smoking, and study-specific and technical variables. Summary results were meta-analyzed within and across ethnicities. Findings were assessed using integrative epigenomics methods and pathway analyses. Results We identified 93 DMPs associated with eGFR at an FDR of 0.05 and replicated 13 and 1 DMPs across independent samples in trans-ethnic and African American meta-analyses, respectively. The study also validated 6 previously published DMPs. Identified DMPs showed significant overlap enrichment with DNase I hypersensitive sites in kidney tissue, sites associated with the expression of proximal genes, and transcription factor motifs and pathways associated with kidney tissue and kidney development. Conclusions We uncovered trans-ethnic and ethnic-specific DMPs associated with eGFR, including DMPs enriched in regulatory elements in kidney tissue and pathways related to kidney development. These findings shed light on epigenetic mechanisms associated with kidney function, bridging the gap between population-specific eGFR-associated DNAm and tissue-specific regulatory context.
Establishment of sex difference in circulating uric acid is associated with higher testosterone and lower sex hormone-binding globulin in adolescent boys
- Wang, Yutang, Charchar, Fadi
- Authors: Wang, Yutang , Charchar, Fadi
- Date: 2021
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 11, no. 1 (2021), p.
- Relation: https://purl.org/au-research/grants/nhmrc/1062671
- Full Text:
- Reviewed:
- Description: Men have higher circulating levels of uric acid than women. This sex difference is suspected to be a result of suppressive effects of estradiol on uric acid. If so, estradiol would be inversely associated with circulating uric acid. This study aimed to test this hypothesis. This cross-sectional study included 9472 participants (weighted sample size of 184,342,210) aged 12–80 years from the 2013 to 2016 US National Health and Nutrition Examination Survey. Associations of sex hormones with uric acid were analyzed using weighted least squares regression, adjusting for demographic characteristics, lifestyle risk factors, and comorbidities. Neither free nor bioavailable estradiol was inversely associated with circulating uric acid in adolescent boys or girls, or adult men or women, or perimenopausal women after full adjustment. The sex difference in uric acid was established during adolescence as a result of a dramatic increase in uric acid in adolescent boys. During adolescence, the increase in estradiol in girls over time was accompanied by a relatively unchanged level of uric acid. All three fractions of estradiol (free, bioavailable, and total) were positively associated with uric acid in adolescent boys and girls after full adjustment. In adolescent boys, all three fractions of testosterone were positively associated with serum uric acid, and sex hormone-binding globulin was inversely associated with uric acid after full adjustment. These results suggest that estradiol is not inversely associated with circulating uric acid in adolescents and the establishment of sex difference in circulating uric acid during adolescence is associated with higher testosterone and lower sex hormone-binding globulin in adolescent boys. © 2021, The Author(s).
- Authors: Wang, Yutang , Charchar, Fadi
- Date: 2021
- Type: Text , Journal article
- Relation: Scientific Reports Vol. 11, no. 1 (2021), p.
- Relation: https://purl.org/au-research/grants/nhmrc/1062671
- Full Text:
- Reviewed:
- Description: Men have higher circulating levels of uric acid than women. This sex difference is suspected to be a result of suppressive effects of estradiol on uric acid. If so, estradiol would be inversely associated with circulating uric acid. This study aimed to test this hypothesis. This cross-sectional study included 9472 participants (weighted sample size of 184,342,210) aged 12–80 years from the 2013 to 2016 US National Health and Nutrition Examination Survey. Associations of sex hormones with uric acid were analyzed using weighted least squares regression, adjusting for demographic characteristics, lifestyle risk factors, and comorbidities. Neither free nor bioavailable estradiol was inversely associated with circulating uric acid in adolescent boys or girls, or adult men or women, or perimenopausal women after full adjustment. The sex difference in uric acid was established during adolescence as a result of a dramatic increase in uric acid in adolescent boys. During adolescence, the increase in estradiol in girls over time was accompanied by a relatively unchanged level of uric acid. All three fractions of estradiol (free, bioavailable, and total) were positively associated with uric acid in adolescent boys and girls after full adjustment. In adolescent boys, all three fractions of testosterone were positively associated with serum uric acid, and sex hormone-binding globulin was inversely associated with uric acid after full adjustment. These results suggest that estradiol is not inversely associated with circulating uric acid in adolescents and the establishment of sex difference in circulating uric acid during adolescence is associated with higher testosterone and lower sex hormone-binding globulin in adolescent boys. © 2021, The Author(s).
Estimation of the TBM advance rate under hard rock conditions using XGBoost and Bayesian optimization
- Zhou, Jian, Qiu, Yingui, Zhu, Shuangli, Armaghani, Danial, Khandelwal, Manoj, Mohamad, Edy
- Authors: Zhou, Jian , Qiu, Yingui , Zhu, Shuangli , Armaghani, Danial , Khandelwal, Manoj , Mohamad, Edy
- Date: 2021
- Type: Text , Journal article
- Relation: Underground Space Vol. 6, no. 5 (Oct 2021), p. 506-515
- Full Text:
- Reviewed:
- Description: The advance rate (AR) of a tunnel boring machine (TBM) under hard rock conditions is a key parameter in the successful implementation of tunneling engineering. In this study, we improved the accuracy of prediction models by employing a hybrid model of extreme gradient boosting (XGBoost) with Bayesian optimization (BO) to model the TBM AR. To develop the proposed models, 1286 sets of data were collected from the Peng Selangor Raw Water Transfer tunnel project in Malaysia. The database consists of rock mass and intact rock features, including rock mass rating, rock quality designation, weathered zone, uniaxial compressive strength, and Brazilian tensile strength. Machine specifications, including revolution per minute and thrust force, were considered to predict the TBM AR. The accuracies of the predictive models were examined using the root mean squares error (RMSE) and the coefficient of determination (R-2) between the observed and predicted yield by employing a five-fold cross-validation procedure. Results showed that the BO algorithm can capture better hyper-parameters for the XGBoost prediction model than can the default XGBoost model. The robustness and generalization of the BO-XGBoost model yielded prominent results with RMSE and R-2 values of 0.0967 and 0.9806 (for the testing phase), respectively. The results demonstrated the merits of the proposed BO-XGBoost model. In addition, variable importance through mutual information tests was applied to interpret the XGBoost model and demonstrated that machine parameters have the greatest impact as compared to rock mass and material properties.
- Authors: Zhou, Jian , Qiu, Yingui , Zhu, Shuangli , Armaghani, Danial , Khandelwal, Manoj , Mohamad, Edy
- Date: 2021
- Type: Text , Journal article
- Relation: Underground Space Vol. 6, no. 5 (Oct 2021), p. 506-515
- Full Text:
- Reviewed:
- Description: The advance rate (AR) of a tunnel boring machine (TBM) under hard rock conditions is a key parameter in the successful implementation of tunneling engineering. In this study, we improved the accuracy of prediction models by employing a hybrid model of extreme gradient boosting (XGBoost) with Bayesian optimization (BO) to model the TBM AR. To develop the proposed models, 1286 sets of data were collected from the Peng Selangor Raw Water Transfer tunnel project in Malaysia. The database consists of rock mass and intact rock features, including rock mass rating, rock quality designation, weathered zone, uniaxial compressive strength, and Brazilian tensile strength. Machine specifications, including revolution per minute and thrust force, were considered to predict the TBM AR. The accuracies of the predictive models were examined using the root mean squares error (RMSE) and the coefficient of determination (R-2) between the observed and predicted yield by employing a five-fold cross-validation procedure. Results showed that the BO algorithm can capture better hyper-parameters for the XGBoost prediction model than can the default XGBoost model. The robustness and generalization of the BO-XGBoost model yielded prominent results with RMSE and R-2 values of 0.0967 and 0.9806 (for the testing phase), respectively. The results demonstrated the merits of the proposed BO-XGBoost model. In addition, variable importance through mutual information tests was applied to interpret the XGBoost model and demonstrated that machine parameters have the greatest impact as compared to rock mass and material properties.
Evaluating sociocultural influences affecting participation and understanding of academic support services and programs (SSPs): Impacts on notions of attrition, retention, and success in higher education
- Weuffen, Sara, Fotinatos, Nina, Andrews, Tulsa
- Authors: Weuffen, Sara , Fotinatos, Nina , Andrews, Tulsa
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of College Student Retention: Research, Theory and Practice Vol. 23, no. 1 (2021), p. 118-138
- Full Text:
- Reviewed:
- Description: While no major change in relation to student attrition and retention data has been recorded over the past 20 years, the increasingly neoliberal agenda imposed on Australian higher education institutions has led to increased scrutiny around such data. In this case study, we explore discourses of attrition and retention to understand better the unique needs of students, and influences of targeted student support programs, as they transition to a regional higher education learning environment. We applied a mixed methods approach via a poststructuralist lens to identify frequency of nodes in relation to dimensions of the Kahu’s conceptual framework of engagement, antecedents and consequences model and present staff (n=6) and student (n=7) perceptions about the tangible value of knowledge, engagement, participation, and reportable outcomes of student support programs. Our findings indicate that staff tend to view student support programs from deficit discourses, whereas students view them as empowering. © The Author(s) 2018.
- Authors: Weuffen, Sara , Fotinatos, Nina , Andrews, Tulsa
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of College Student Retention: Research, Theory and Practice Vol. 23, no. 1 (2021), p. 118-138
- Full Text:
- Reviewed:
- Description: While no major change in relation to student attrition and retention data has been recorded over the past 20 years, the increasingly neoliberal agenda imposed on Australian higher education institutions has led to increased scrutiny around such data. In this case study, we explore discourses of attrition and retention to understand better the unique needs of students, and influences of targeted student support programs, as they transition to a regional higher education learning environment. We applied a mixed methods approach via a poststructuralist lens to identify frequency of nodes in relation to dimensions of the Kahu’s conceptual framework of engagement, antecedents and consequences model and present staff (n=6) and student (n=7) perceptions about the tangible value of knowledge, engagement, participation, and reportable outcomes of student support programs. Our findings indicate that staff tend to view student support programs from deficit discourses, whereas students view them as empowering. © The Author(s) 2018.
Evaluating the effects of a therapeutic day rehabilitation program and inclusion of gardening in an Australian rural community health service
- Missen, Karen, Alindogan, Mark, Forrest, Scott, Waller, Susan
- Authors: Missen, Karen , Alindogan, Mark , Forrest, Scott , Waller, Susan
- Date: 2021
- Type: Text , Journal article
- Relation: Australian Journal of Primary Health Vol. 27, no. 6 (2021), p. 496-502
- Full Text:
- Reviewed:
- Description: Therapeutic day rehabilitation (TDR) is a non-residential intensive structured program designed for individuals recovering from substance misuse. A weekly afternoon of therapeutic gardening was a new incentive initiated in a TDR program at one Australian community health service, designed to give participants the opportunity to spend time outdoors connecting with nature and each other. The aim of this study was to explore perceptions of participants enrolled in this program by employing a convergent parallel mixed-method design using qualitative individual, semi-structured interviews (n = 14) and longitudinal quantitative quality of life (QOL) data at three different intervals (n = 17). The analysis of the quantitative data showed that there was a statistically significant increase in the participants' QOL scores in three of four domains (physical health, psychological, social relationships) when comparing baseline and post completion of the TDR. These observed changes were maintained at the 4-week follow up. The key findings from the semi-structured interviews include positive effects for participants on social connectivity, structure and achievement, understanding of recovery and relaxation from contact with nature. This study shows that a combination of TDR and therapeutic gardening can improve participants' physical health, psychological health and social relationships. © 2021 La Trobe University.
- Authors: Missen, Karen , Alindogan, Mark , Forrest, Scott , Waller, Susan
- Date: 2021
- Type: Text , Journal article
- Relation: Australian Journal of Primary Health Vol. 27, no. 6 (2021), p. 496-502
- Full Text:
- Reviewed:
- Description: Therapeutic day rehabilitation (TDR) is a non-residential intensive structured program designed for individuals recovering from substance misuse. A weekly afternoon of therapeutic gardening was a new incentive initiated in a TDR program at one Australian community health service, designed to give participants the opportunity to spend time outdoors connecting with nature and each other. The aim of this study was to explore perceptions of participants enrolled in this program by employing a convergent parallel mixed-method design using qualitative individual, semi-structured interviews (n = 14) and longitudinal quantitative quality of life (QOL) data at three different intervals (n = 17). The analysis of the quantitative data showed that there was a statistically significant increase in the participants' QOL scores in three of four domains (physical health, psychological, social relationships) when comparing baseline and post completion of the TDR. These observed changes were maintained at the 4-week follow up. The key findings from the semi-structured interviews include positive effects for participants on social connectivity, structure and achievement, understanding of recovery and relaxation from contact with nature. This study shows that a combination of TDR and therapeutic gardening can improve participants' physical health, psychological health and social relationships. © 2021 La Trobe University.
- Tribe, Jarryd, Koroznikova, Larissa, Khandelwal, Manoj, Giri, Jason
- Authors: Tribe, Jarryd , Koroznikova, Larissa , Khandelwal, Manoj , Giri, Jason
- Date: 2021
- Type: Text , Journal article
- Relation: Natural Resources Research Vol. 30, no. 6 (2021), p. 4673-4694
- Full Text: false
- Reviewed:
- Description: Ground vibrations induced during rock fragmentation by blasting remain a potential source of hazard for the stability of nearby structures. In this paper, to forecast the effect of blast-induced ground vibrations, dimensional analysis (DA) is proposed to predict peak particle velocity (PPV). In conventional predictor equations, the major and critical parameter for the estimation of PPV is square root scaled distance. The new formula based on DA was obtained considering various blast design parameters in order to improve the capability of PPV prediction. After obtaining the new DA equation for the prediction of PPV, 360 data sets were used to determine the unknown coefficients of the new equation as well as site constants of different conventional predictor equations. Then, ten additional randomly selected data sets were used to compare the capability of the new model with conventional predictor equations. The results were compared based on coefficient of determination (R2) and mean absolute error (MAE) between measured and predicted values of PPV. The proposed formula with the greatest R2 and the lowest MAE was the better option for predicting the PPV of induced vibrations for the measured field data. © 2021, International Association for Mathematical Geosciences.
- Missen, Karen, Mills, Alyssa, McDonald, Georgia, Di Corleto, Erin, Telling, Laura, Davey, Alice
- Authors: Missen, Karen , Mills, Alyssa , McDonald, Georgia , Di Corleto, Erin , Telling, Laura , Davey, Alice
- Date: 2021
- Type: Text , Journal article
- Relation: Australian Journal of Rural Health Vol. 29, no. 6 (2021), p. 987-992
- Full Text: false
- Reviewed:
- Description: Objective Community occupational therapy services have seen an increase in demand over the last three years, resulting in longer waitlist times for service provision, particularly in rural areas where it is difficult to recruit experienced occupational therapists. Utilising a demand management model, the Basic Assessment Model Pre‐Screening Tool was developed by a team of Occupational Therapists and allied health assistants to decrease client waitlist times at one rural community health service. Design An evaluation of the implementation of an assessment model with comparison of quantitative data pre and post intervention. Setting Rural Community Health Service in Victoria, Australia Participants 456 clients that were registered as community‐based clients requiring occupational therapy services. Main Outcome measure Following the implementation of the newly developed Basic Assessment Model the number of occupational therapy assessments increased and there was a decrease in the median wait time that clients were on the waitlist in comparison to pre implementation. Results There was a statistically significant decrease (p<0.001) in the median number of days spent on the waitlist for the post intervention group (80 days) compared to the pre intervention group (105 days). Conclusion The results of this study suggest that waiting lists for community occupational therapy services can be reduced by implementing this basic assessment model ultimately improving the health outcomes of clients.
- Shahabuddin, M., Kibria, M., Bhattacharya, Sankar
- Authors: Shahabuddin, M. , Kibria, M. , Bhattacharya, Sankar
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of the Energy Institute Vol. 94, no. (2021), p. 294-309
- Full Text: false
- Reviewed:
- Description: This study used an entrained flow gasifier to assess the pyrolysis and gasification performance of Bangladeshi Barapukurian bituminous coal. The pyrolysis and CO2 gasification were conducted at temperatures of 1000°C–1400 °C under atmospheric pressure. The carbon conversion, syngas yield and pollutant emissions of coal using two different particle size of 90–106 and 250–300 μm have been analysed under CO2 concentration of 10–80 vol%. Solid residue (char/ash) was analysed by using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD) methods. Results show that the release of volatile matter increases up to the temperature of 1200 °C. However, the temperature needs to increase at 1400 °C for the complete carbon conversion. Based on the CO/H2 ratio, syngas conditioning is required while using a temperature of 1200 °C or above, especially over the stoichiometric CO2 concentrations. Considering the heating value of syngas for power generation, the use of CO2 should be limited to less than 20% at a temperature of 1200–1400 °C. Particle size is important for carbon conversion but there is no significant impact on the heating value of syngas. Installation of the syngas cleaning system is required to drop the pollutants emission from the ppmv range to the ppbv range. © 2020 Energy Institute
Evolution of twinning during cyclic loading of magnesium alloy examined by quasi-in-situ EBSD
- Fallahi, Hossein, Davies, Chris
- Authors: Fallahi, Hossein , Davies, Chris
- Date: 2021
- Type: Text , Journal article
- Relation: Materials Science and Engineering A Vol. 820, no. (2021), p.
- Full Text: false
- Reviewed:
- Description: Most complex engineering components experience varied loading in use. We conducted successive experiments of cyclic tensile deformation followed by electron-backscattered diffraction imaging of the same area on each of several magnesium alloy (ZM) sample to investigate the microstructure and texture evolution during cyclic loading. In this way we correlated the evolving deformed microstructure of cyclically loaded magnesium to the initial grain orientations. To investigate the effects of the strain path, the behaviour of samples with and without pre-compression was compared. Twins can propagate from grain to grain and twin chains will form in the material without any pre-deformation. Twin chains are a result of twin transmission at grain boundaries and twin transmission frequency decreases with increasing grain boundary angles. In the absence of pre-compression, the extension twin fraction rises from 0.003 to 0.019 after two cycles of tensile loading to a strain of 0.03, after which it changes only slightly as strain is increased. Twin chains in the pre-compressed specimen are activated without any obvious dependence on the matrix orientation. The fraction of extension twinning is 0.2 for the pre-compressed specimen. After a cycle of tensile loading to a total plastic strain of 0.015, 90% of the extension twins undergo detwinning. The detwinning starts just after reverse loading. Secondary twins forming within primary twin interfaces start to nucleate in the microstructure of the pre-compressed material at an early stage (at plastic strain values of 0.056). This is different from the nucleation of secondary twins in the material without pre-compression that occurs at a strain of 0.104. The early formation of secondary twinning is due to the presence of residual primary twins in the microstructure of the pre-compressed material as a result of detwinning of the initial twins. © 2021
Examination of effective VAr with respect to dynamic voltage stability in renewable rich power grids
- Alzahrani, Saeed, Shah, Rakibuzzaman, Mithulananthan, N.
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 75494-75508
- Full Text:
- Reviewed:
- Description: High penetrations of inverter-based renewable resources (IBRs) diminish the resilience that traditional power systems had due to constant research and developments for many years. In particular, dynamic voltage stability becomes one of the major concerns for transmission system operators due to the limited capabilities of IBRs (i.e., voltage and frequency regulation). A heavily loaded renewable-rich network is susceptible to fault-induced delayed voltage recovery (FIDVR) due to insufficient effective reactive power (E-VAr) in power grids. Hence, it is crucial to thoroughly scrutinize each VAr resources' participation in E-VAr under various operating conditions. Moreover, it is essential to investigate the influence of E-VAr on system post-fault performance. The E-VAr investigation would help in determining the optimal location and sizing of grid-connected IBRs and allow more renewable energy integration. Furthermore, it would enrich decision-making about adopting additional grid support devices. In this paper, a comprehensive assessment framework is utilized to assess the E-VAr of a power system with a large-scale photovoltaic power. Plant under different realistic operating conditions. Several indices quantifying the contribution of VAr resources and load bus voltage recovery assists to explore the transient response and voltage trajectories. The recovery indices help have a better understanding of the factors affecting E-VAr. The proposed framework has been tested in the New England (IEEE 39 bus system) through simulation by DIgSILENT Power Factory. © 2013 IEEE.
Examination of effective VAr with respect to dynamic voltage stability in renewable rich power grids
- Authors: Alzahrani, Saeed , Shah, Rakibuzzaman , Mithulananthan, N.
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Access Vol. 9, no. (2021), p. 75494-75508
- Full Text:
- Reviewed:
- Description: High penetrations of inverter-based renewable resources (IBRs) diminish the resilience that traditional power systems had due to constant research and developments for many years. In particular, dynamic voltage stability becomes one of the major concerns for transmission system operators due to the limited capabilities of IBRs (i.e., voltage and frequency regulation). A heavily loaded renewable-rich network is susceptible to fault-induced delayed voltage recovery (FIDVR) due to insufficient effective reactive power (E-VAr) in power grids. Hence, it is crucial to thoroughly scrutinize each VAr resources' participation in E-VAr under various operating conditions. Moreover, it is essential to investigate the influence of E-VAr on system post-fault performance. The E-VAr investigation would help in determining the optimal location and sizing of grid-connected IBRs and allow more renewable energy integration. Furthermore, it would enrich decision-making about adopting additional grid support devices. In this paper, a comprehensive assessment framework is utilized to assess the E-VAr of a power system with a large-scale photovoltaic power. Plant under different realistic operating conditions. Several indices quantifying the contribution of VAr resources and load bus voltage recovery assists to explore the transient response and voltage trajectories. The recovery indices help have a better understanding of the factors affecting E-VAr. The proposed framework has been tested in the New England (IEEE 39 bus system) through simulation by DIgSILENT Power Factory. © 2013 IEEE.
Examining factors that influence the relationship between personality and stress
- Authors: Duggan, Leanne
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Individual differences in the stress response have been linked with numerous factors, including personality traits and mindfulness. Selye (1950) was among the first to detail the physiological stress response that takes place during a stressful event, or after exposure to a stressor. These responses include heart rate changes and the secretion of cortisol into the blood stream, which are key physiological indicators that a stress response is taking place. Lazarus and Folkman (1984) examined appraisal of stressful events, determining that this is crucial to the stress experience. An extension of Lazarus and Folkman’s cognitive appraisal theory was offered by Vollrath (2001), suggesting an individual’s personality accentuates our stress response, therefore, offering an explanation for the individual differences evident in stress responses. The relationship between personality and stress is not straight forward, and other factors, such as affect and mindfulness, may influence this relationship. Thus, this dissertation is divided into three studies. Study 1 examined the moderating and mediating factors of affect on the relationship between personality traits and perceived stress. A total of 290 adults (71% female; Mage = 35.0 years, SD = 12.92) completed an online questionnaire package, comprising of the Perceived Stress Scale, Big Five Inventory, Positive and Negative Affect Schedule, and a number of demographic questions. A hierarchical regression showed that 56% of the variance in perceived stress was explained by personality and affect, and when all personality traits were viewed concurrently and with affect, neuroticism was the only one to significantly explain variance in perceived stress. No moderation effects were found in Study 1 however, positive affect partially mediated the relationship between neuroticism and perceived stress. Study 2 aimed to further the findings of Study 1 by investigating whether trait mindfulness impacted the relationship between personality and stress. A total of 266 adults (70% female; Mage = 34.0 years, SD = 12.68) completed an online questionnaire package, consisting of the Perceived Stress Scale, Big Five Inventory, and Carolina Empirically Derived Mindfulness Scale. A hierarchical regression showed that 58% of the variance in perceived stress was explained by personality and trait mindfulness. When all personality traits and trait mindfulness were viewed together, neuroticism and agreeableness were the only personality traits to significantly explain variance in perceived stress. The sub-scale trait mindfulness attention significantly moderated the relationship between agreeableness and perceived stress, while a partial mediation was found between neuroticism and the sub-scale trait mindfulness acceptance. Study 3 investigated the effectiveness of a brief state-based mindfulness intervention on physiological (cortisol and heart rate) and psychological stress responses, in a participant matched design. A total of 20 participants (60% female; Mage = 34.60 years, SD = 14.68) were recruited from Studies 1 and/or 2 and matched based on gender, dominant personality trait (found in Study 1 and 2), and perceived stress. One participant in each matched pair was then randomly allocated to the mindfulness experimental, or control, group. The mindfulness experimental group completed a 10-minute breathing exercise, prior to completing the Trier Social Stress Test, a verbal presentation and arithmetic task, designed to induce stress. The control group did not complete any activity prior to the stress test. Comparison of the groups indicated that no significant differences in perceived stress were evident pre-post- intervention. Changes in heart rate were noted for all participants during the intervention, though no difference was evident between groups. The results of Study 3 indicate a mindfulness breathing exercise makes little difference to physiological stress responses during a stress task. The combined findings of this dissertation indicate that personality traits can influence the likelihood of an individual experiencing stress. Mindfulness and affect also impact on the relationship between personality and stress and offer some insight into the individual experience of stress responses.
- Description: Doctor of Philosophy
- Authors: Duggan, Leanne
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Individual differences in the stress response have been linked with numerous factors, including personality traits and mindfulness. Selye (1950) was among the first to detail the physiological stress response that takes place during a stressful event, or after exposure to a stressor. These responses include heart rate changes and the secretion of cortisol into the blood stream, which are key physiological indicators that a stress response is taking place. Lazarus and Folkman (1984) examined appraisal of stressful events, determining that this is crucial to the stress experience. An extension of Lazarus and Folkman’s cognitive appraisal theory was offered by Vollrath (2001), suggesting an individual’s personality accentuates our stress response, therefore, offering an explanation for the individual differences evident in stress responses. The relationship between personality and stress is not straight forward, and other factors, such as affect and mindfulness, may influence this relationship. Thus, this dissertation is divided into three studies. Study 1 examined the moderating and mediating factors of affect on the relationship between personality traits and perceived stress. A total of 290 adults (71% female; Mage = 35.0 years, SD = 12.92) completed an online questionnaire package, comprising of the Perceived Stress Scale, Big Five Inventory, Positive and Negative Affect Schedule, and a number of demographic questions. A hierarchical regression showed that 56% of the variance in perceived stress was explained by personality and affect, and when all personality traits were viewed concurrently and with affect, neuroticism was the only one to significantly explain variance in perceived stress. No moderation effects were found in Study 1 however, positive affect partially mediated the relationship between neuroticism and perceived stress. Study 2 aimed to further the findings of Study 1 by investigating whether trait mindfulness impacted the relationship between personality and stress. A total of 266 adults (70% female; Mage = 34.0 years, SD = 12.68) completed an online questionnaire package, consisting of the Perceived Stress Scale, Big Five Inventory, and Carolina Empirically Derived Mindfulness Scale. A hierarchical regression showed that 58% of the variance in perceived stress was explained by personality and trait mindfulness. When all personality traits and trait mindfulness were viewed together, neuroticism and agreeableness were the only personality traits to significantly explain variance in perceived stress. The sub-scale trait mindfulness attention significantly moderated the relationship between agreeableness and perceived stress, while a partial mediation was found between neuroticism and the sub-scale trait mindfulness acceptance. Study 3 investigated the effectiveness of a brief state-based mindfulness intervention on physiological (cortisol and heart rate) and psychological stress responses, in a participant matched design. A total of 20 participants (60% female; Mage = 34.60 years, SD = 14.68) were recruited from Studies 1 and/or 2 and matched based on gender, dominant personality trait (found in Study 1 and 2), and perceived stress. One participant in each matched pair was then randomly allocated to the mindfulness experimental, or control, group. The mindfulness experimental group completed a 10-minute breathing exercise, prior to completing the Trier Social Stress Test, a verbal presentation and arithmetic task, designed to induce stress. The control group did not complete any activity prior to the stress test. Comparison of the groups indicated that no significant differences in perceived stress were evident pre-post- intervention. Changes in heart rate were noted for all participants during the intervention, though no difference was evident between groups. The results of Study 3 indicate a mindfulness breathing exercise makes little difference to physiological stress responses during a stress task. The combined findings of this dissertation indicate that personality traits can influence the likelihood of an individual experiencing stress. Mindfulness and affect also impact on the relationship between personality and stress and offer some insight into the individual experience of stress responses.
- Description: Doctor of Philosophy
Exclusive breastfeeding continuation and associated factors among employed women in North Ethiopia : a cross-sectional study
- Gebrekidan, Kahsu, Hall, Helen, Plummer, Virginia, Fooladi, Ensieh
- Authors: Gebrekidan, Kahsu , Hall, Helen , Plummer, Virginia , Fooladi, Ensieh
- Date: 2021
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 16, no. 7 (2021), p.
- Full Text:
- Reviewed:
- Description: Background Exclusive Breastfeeding (EBF) can prevent up to 13% of under-five mortality in developing countries. In Sub-Saharan Africa the rate of EBF at six months remains very low at 36%. Different types of factors such as maternal, family and work-related factors are responsible for the low rate of EBF among employed women. This study aimed to assess the prevalence of EBF continuation and associated factors among employed women in North Ethiopia. Materials and methods A community-based, cross-sectional study was conducted in two towns of Tigray region, North Ethiopia. Employed women who had children between six months and two years were surveyed using multistage, convenience sampling. Women filled in a paper based validated questionnaire adopted from the Breastfeeding and Employment Study toolkit (BESt). The questions were grouped into four parts of sociodemographic characteristics, maternal characteristics, family support and work-related factors. Factors associated with EBF continuation as a binary outcome (yes/no) were determined using multivariable logistic regression. Results Four-hundred and forty-nine women participated in this study with a mean (SD) age 30.4 (4.2) years. Two hundred and fifty-four (56.4%) participants exclusively breastfed their children for six months or more. The main reason for discontinuation of EBF was the requirement of women to return to paid employment (31.5%). Four-hundred and forty (98.2%) participants believed that breastfeeding has benefits either to the infant or to the mother. Three hundred and seventy-one (82.8%) of the participants received support from their family at home to assist with EBF, most commonly from their husbands and mothers. Having family support (adjusted odds ratio [AOR] = 2.1, 95%, CI 1.2–3.6; P = 0.005), having frequent breaks at work (AOR = 2.6, 95% CI, 1.4–4.8; P = 0.002) and the possibility of buying or borrowing required equipment for expressing breast milk (AOR = 1.7, 95% CI, 1.0–3.0; P = 0.033) were statistically associated with an increased chance of EBF. Conclusion Although returning to work was reported by the study participants as the main reason for discontinuation of EBF, families and managers’ support play significant roles in EBF continuation, which in the absence of six-month’s maternity leave for employed women in Ethiopia would be of benefit to both mothers and children. © 2021 Gebrekidan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- Authors: Gebrekidan, Kahsu , Hall, Helen , Plummer, Virginia , Fooladi, Ensieh
- Date: 2021
- Type: Text , Journal article
- Relation: PLoS ONE Vol. 16, no. 7 (2021), p.
- Full Text:
- Reviewed:
- Description: Background Exclusive Breastfeeding (EBF) can prevent up to 13% of under-five mortality in developing countries. In Sub-Saharan Africa the rate of EBF at six months remains very low at 36%. Different types of factors such as maternal, family and work-related factors are responsible for the low rate of EBF among employed women. This study aimed to assess the prevalence of EBF continuation and associated factors among employed women in North Ethiopia. Materials and methods A community-based, cross-sectional study was conducted in two towns of Tigray region, North Ethiopia. Employed women who had children between six months and two years were surveyed using multistage, convenience sampling. Women filled in a paper based validated questionnaire adopted from the Breastfeeding and Employment Study toolkit (BESt). The questions were grouped into four parts of sociodemographic characteristics, maternal characteristics, family support and work-related factors. Factors associated with EBF continuation as a binary outcome (yes/no) were determined using multivariable logistic regression. Results Four-hundred and forty-nine women participated in this study with a mean (SD) age 30.4 (4.2) years. Two hundred and fifty-four (56.4%) participants exclusively breastfed their children for six months or more. The main reason for discontinuation of EBF was the requirement of women to return to paid employment (31.5%). Four-hundred and forty (98.2%) participants believed that breastfeeding has benefits either to the infant or to the mother. Three hundred and seventy-one (82.8%) of the participants received support from their family at home to assist with EBF, most commonly from their husbands and mothers. Having family support (adjusted odds ratio [AOR] = 2.1, 95%, CI 1.2–3.6; P = 0.005), having frequent breaks at work (AOR = 2.6, 95% CI, 1.4–4.8; P = 0.002) and the possibility of buying or borrowing required equipment for expressing breast milk (AOR = 1.7, 95% CI, 1.0–3.0; P = 0.033) were statistically associated with an increased chance of EBF. Conclusion Although returning to work was reported by the study participants as the main reason for discontinuation of EBF, families and managers’ support play significant roles in EBF continuation, which in the absence of six-month’s maternity leave for employed women in Ethiopia would be of benefit to both mothers and children. © 2021 Gebrekidan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Exploration and model development for emergency department waiting room nurse role : synthesis of a three-phase sequential mixed methods study
- Innes, Kelli, Jackson, Debra, Plummer, Virginia, Elliott, Doug
- Authors: Innes, Kelli , Jackson, Debra , Plummer, Virginia , Elliott, Doug
- Date: 2021
- Type: Text , Journal article
- Relation: International Emergency Nursing Vol. 59, no. (2021), p.
- Full Text:
- Reviewed:
- Description: Background: To improve flow and care in waiting rooms, some emergency departments introduced a specific nursing role to care for this patient cohort with the aim of commencing interventions early, improving patient safety by reassessing and enhancing communication. The objective of the research was to explore to what extent does qualitative interviews and quantitative survey contribute to describing emergency department waiting room nurses, through integration and synthesis of findings from a multiphase mixed methods study. Methods: Multiphase mixed methods exploratory sequential design with integration of findings. Data integration occurred during the phases and when assimilating all findings. Findings: Experienced emergency nurses, preferably with graduate qualifications, who are autonomous practitioners with highly developed communication skills, clinical decision making and proficiency in assessment and monitoring are required to perform the role. The waiting room nurse provides patient-centered care and ensures safe, timely care is delivered to those in the waiting room. A standardised approach and high risk of exposure to occupational stressors need to be considered. Conclusions: This mixed methods sequential design explored the waiting room nurse role from the perspective of emergency nurses generating new knowledge into the role. This advanced practice nursing role contributes to patient safety and delivery of patient centred care in the emergency department waiting room. © 2021 Elsevier Ltd
- Authors: Innes, Kelli , Jackson, Debra , Plummer, Virginia , Elliott, Doug
- Date: 2021
- Type: Text , Journal article
- Relation: International Emergency Nursing Vol. 59, no. (2021), p.
- Full Text:
- Reviewed:
- Description: Background: To improve flow and care in waiting rooms, some emergency departments introduced a specific nursing role to care for this patient cohort with the aim of commencing interventions early, improving patient safety by reassessing and enhancing communication. The objective of the research was to explore to what extent does qualitative interviews and quantitative survey contribute to describing emergency department waiting room nurses, through integration and synthesis of findings from a multiphase mixed methods study. Methods: Multiphase mixed methods exploratory sequential design with integration of findings. Data integration occurred during the phases and when assimilating all findings. Findings: Experienced emergency nurses, preferably with graduate qualifications, who are autonomous practitioners with highly developed communication skills, clinical decision making and proficiency in assessment and monitoring are required to perform the role. The waiting room nurse provides patient-centered care and ensures safe, timely care is delivered to those in the waiting room. A standardised approach and high risk of exposure to occupational stressors need to be considered. Conclusions: This mixed methods sequential design explored the waiting room nurse role from the perspective of emergency nurses generating new knowledge into the role. This advanced practice nursing role contributes to patient safety and delivery of patient centred care in the emergency department waiting room. © 2021 Elsevier Ltd
- Innes, Kelli, Jackson, Debra, Plummer, Virginia, Elliott, Doug
- Authors: Innes, Kelli , Jackson, Debra , Plummer, Virginia , Elliott, Doug
- Date: 2021
- Type: Text , Journal article
- Relation: International Emergency Nursing Vol. 59, no. (2021), p.
- Full Text: false
- Reviewed:
- Description: Background: To improve flow and care in waiting rooms, some emergency departments introduced a specific nursing role to care for this patient cohort with the aim of commencing interventions early, improving patient safety by reassessing and enhancing communication. The objective of the research was to explore to what extent does qualitative interviews and quantitative survey contribute to describing emergency department waiting room nurses, through integration and synthesis of findings from a multiphase mixed methods study. Methods: Multiphase mixed methods exploratory sequential design with integration of findings. Data integration occurred during the phases and when assimilating all findings. Findings: Experienced emergency nurses, preferably with graduate qualifications, who are autonomous practitioners with highly developed communication skills, clinical decision making and proficiency in assessment and monitoring are required to perform the role. The waiting room nurse provides patient-centered care and ensures safe, timely care is delivered to those in the waiting room. A standardised approach and high risk of exposure to occupational stressors need to be considered. Conclusions: This mixed methods sequential design explored the waiting room nurse role from the perspective of emergency nurses generating new knowledge into the role. This advanced practice nursing role contributes to patient safety and delivery of patient centred care in the emergency department waiting room. © 2021 Elsevier Ltd
Exploring interprofessional clinical placements to understand perceptions and outcomes for pre-registration healthcare students
- Authors: Hood, Kerry
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background There is an ongoing need for preregistration healthcare students to acquire skills that equip them to collaborate with others for patient-centred care and outcomes. Traditional models of university learning and clinical placement seldom offer students the opportunities to experience interprofessional learning or to ‘test the waters’ of collaborative practice. Aims A range of interprofessional learning opportunities were offered to preregistration healthcare students while on clinical placement in a large metropolitan health service. This research evaluated interprofessional learning opportunities for preregistration healthcare students as preparation for collaborative practice. It also explored the perceived value for student learning of these activities and examined the challenges and opportunities accompanying the design and implementation of the student-led beds model. Methods A mixed methods approach was undertaken. In particular, there was a focus on the experiences of students in an immersive two-week interprofessional placement in which interprofessional student teams worked together to lead the care of inpatients in a variety of clinical settings. This experience enabled students to experience authentic collaborative practice in a real clinical setting. The Theory of Planned Behaviour was used to retrospectively evaluate the findings presented in the published papers. Outcomes This research reflects a journey of student experience of clinical interprofessional learning (IPL), from understanding attitudes to IPL to perceptions of clinical workshops and culminating in the experience of an immersive clinical placement. Outcomes included positive learning experiences and a sense of clarity of professional and interprofessional identity. The model of placement was informed by the international literature, most notably the ‘student-led bed’ model pioneered at Karolinska Institute in Sweden. Despite solid evidence of the usefulness and efficacy of this model, it is yet to be embedded in clinical environments across the world. This research demonstrated that the model can be successfully implemented in a metropolitan health service and may contribute to real behavioural change of our future health professionals
- Description: Doctor of Philosophy
- Authors: Hood, Kerry
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Background There is an ongoing need for preregistration healthcare students to acquire skills that equip them to collaborate with others for patient-centred care and outcomes. Traditional models of university learning and clinical placement seldom offer students the opportunities to experience interprofessional learning or to ‘test the waters’ of collaborative practice. Aims A range of interprofessional learning opportunities were offered to preregistration healthcare students while on clinical placement in a large metropolitan health service. This research evaluated interprofessional learning opportunities for preregistration healthcare students as preparation for collaborative practice. It also explored the perceived value for student learning of these activities and examined the challenges and opportunities accompanying the design and implementation of the student-led beds model. Methods A mixed methods approach was undertaken. In particular, there was a focus on the experiences of students in an immersive two-week interprofessional placement in which interprofessional student teams worked together to lead the care of inpatients in a variety of clinical settings. This experience enabled students to experience authentic collaborative practice in a real clinical setting. The Theory of Planned Behaviour was used to retrospectively evaluate the findings presented in the published papers. Outcomes This research reflects a journey of student experience of clinical interprofessional learning (IPL), from understanding attitudes to IPL to perceptions of clinical workshops and culminating in the experience of an immersive clinical placement. Outcomes included positive learning experiences and a sense of clarity of professional and interprofessional identity. The model of placement was informed by the international literature, most notably the ‘student-led bed’ model pioneered at Karolinska Institute in Sweden. Despite solid evidence of the usefulness and efficacy of this model, it is yet to be embedded in clinical environments across the world. This research demonstrated that the model can be successfully implemented in a metropolitan health service and may contribute to real behavioural change of our future health professionals
- Description: Doctor of Philosophy
Exploring the development of thinking in senior secondary mathematics : a focus on probability
- Authors: Ernst, Heather
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Higher order thinking skills have been identified as desirable although elusive outcomes of many educational curricula. Through a qualitative case study, the alignment between the three levels of the curriculum: intended, implemented, and attained, was examined to determine the tensions and possibilities in the development of mathematical and thinking skills in senior secondary students in Gippsland, a large regional area of Victoria, Australia. Probability was the mathematical content area of focus. Data from document analysis of the intended curriculum, textbooks as the implemented curriculum, and assessments as the attained curriculum, was combined with qualitative data from semi-structured interviews with twenty students and fourteen senior secondary mathematics teachers. These diverse data sources scaffolded each other to identify tensions and possibilities influencing development of student thinking in senior secondary mathematics. This research demonstrated that the flow of content via the intended-implemented-attained curriculum was not adequate to describe all the influences on student learning. The lens of Activity Theory (Engeström, 2001) came closer to capturing the related complexities whereby the textbooks, calculators, bound reference books and assessments, combined with the balance of agency demonstrated by the teachers and students, were found to both support and cause tensions within the activity system. Probability was found to be a valuable topic to study in relation to the development of thinking skills due to its relevance in decision making, how it linked many areas of mathematics and the uniqueness of the classic, experimental, and subjective views of probability. This study is significant in the contribution it makes to understanding the tensions and possibilities associated with the development of mathematical thinking relating to probability through the lens of Activity Theory. While the intended curriculum encouraged a range of thinking skills, this intended curriculum could be implemented in a way that promotes memorisation rather than the intended higher order thinking. This study concludes with recommendations for the curriculum designers, textbook publishers, teachers, and students which may support the development of mathematical and thinking skills.
- Description: Doctor of Philosophy
- Authors: Ernst, Heather
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Higher order thinking skills have been identified as desirable although elusive outcomes of many educational curricula. Through a qualitative case study, the alignment between the three levels of the curriculum: intended, implemented, and attained, was examined to determine the tensions and possibilities in the development of mathematical and thinking skills in senior secondary students in Gippsland, a large regional area of Victoria, Australia. Probability was the mathematical content area of focus. Data from document analysis of the intended curriculum, textbooks as the implemented curriculum, and assessments as the attained curriculum, was combined with qualitative data from semi-structured interviews with twenty students and fourteen senior secondary mathematics teachers. These diverse data sources scaffolded each other to identify tensions and possibilities influencing development of student thinking in senior secondary mathematics. This research demonstrated that the flow of content via the intended-implemented-attained curriculum was not adequate to describe all the influences on student learning. The lens of Activity Theory (Engeström, 2001) came closer to capturing the related complexities whereby the textbooks, calculators, bound reference books and assessments, combined with the balance of agency demonstrated by the teachers and students, were found to both support and cause tensions within the activity system. Probability was found to be a valuable topic to study in relation to the development of thinking skills due to its relevance in decision making, how it linked many areas of mathematics and the uniqueness of the classic, experimental, and subjective views of probability. This study is significant in the contribution it makes to understanding the tensions and possibilities associated with the development of mathematical thinking relating to probability through the lens of Activity Theory. While the intended curriculum encouraged a range of thinking skills, this intended curriculum could be implemented in a way that promotes memorisation rather than the intended higher order thinking. This study concludes with recommendations for the curriculum designers, textbook publishers, teachers, and students which may support the development of mathematical and thinking skills.
- Description: Doctor of Philosophy
- Li, Yong, Liu, Shunpan, Zhu, Xia, Hu, Jiefeng, Zhang, Min, Mai, Ruikun, He, Zhengyou
- Authors: Li, Yong , Liu, Shunpan , Zhu, Xia , Hu, Jiefeng , Zhang, Min , Mai, Ruikun , He, Zhengyou
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Transactions on Power Electronics Vol. 36, no. 7 (2021), p. 7513-7525
- Full Text: false
- Reviewed:
- Description: To maintain a stable output voltage under various operating conditions without introducing extra dc/dc converters, phase-shift (PS) control is usually adopted for wireless power transfer (WPT) systems. By using this method, however, zero-voltage switching (ZVS) operation cannot be guaranteed, especially in light-load conditions. To achieve high efficiency and reduce electromagnetic interference, it is significant for WPT systems to achieve ZVS operation of all switching devices in the whole operation range. In this article, an auxiliary variable inductor, of which the equivalent inductance can be controlled by adjusting the dc current in its auxiliary winding, is designed for series-series-compensated WPT systems under PS control to mitigate the loss arising from hard switching. As a result, a wide ZVS operation range of all switching devices can be achieved. A laboratory prototype is built to verify the theoretical analysis. The experimental results show that, under load and magnetic coupling variations, ZVS operation at fixed operation frequency as well as a constant dc output voltage can be maintained. Compared to the conventional method with only PS control, the proposed WPT can achieve higher overall efficiency in a wider load range owing to the wide ZVS operation range. © 1986-2012 IEEE.
EYE: Visual art and design 2020 graduating students
- Date: 2021
- Type: Text , Artwork , Visual art work
- Full Text: false
- Description: 11 MAR - 1 APR 2021 Anthea BIDWELL Vienna Drysdale BISCHARD Jessica CHAPLIN Kathryn DRUM Miles FOLEY Tameka HAGUE Clayton KEEFE Angeline KOOT Lauren MATTHEWS Tess MCLOUGHLAN Sarah TAYLOR Brittany TUCKER Ella YOUNG Showcasing work by our 2020 visual art and design graduating students within the Bachelor of Visual Arts, Bachelor of Communication Design, Creative Arts (Honours) and Advanced Diploma of Graphic Design, Ballarat, this exhibition has been curated at the School of Arts Post Office Gallery following our virtual exhibition launch in 2020. Image: Vienna Drysdale Bischard Figure 2, 2020 digital print on archival paper H50 X W35 cm Courtesy the artist
- Description: 11 MAR - 1 APR 2021 Anthea BIDWELL Vienna Drysdale BISCHARD Jessica CHAPLIN Kathryn DRUM Miles FOLEY Tameka HAGUE Clayton KEEFE Angeline KOOT Lauren MATTHEWS Tess MCLOUGHLAN Sarah TAYLOR Brittany TUCKER Ella YOUNG Showcasing work by our 2020 visual art and design graduating students within the Bachelor of Visual Arts, Bachelor of Communication Design, Creative Arts (Honours) and Advanced Diploma of Graphic Design, Ballarat, this exhibition has been curated at the School of Arts Post Office Gallery following our virtual exhibition launch in 2020.
- Date: 2021
- Type: Text , Artwork , Visual art work
- Full Text: false
- Description: 11 MAR - 1 APR 2021 Anthea BIDWELL Vienna Drysdale BISCHARD Jessica CHAPLIN Kathryn DRUM Miles FOLEY Tameka HAGUE Clayton KEEFE Angeline KOOT Lauren MATTHEWS Tess MCLOUGHLAN Sarah TAYLOR Brittany TUCKER Ella YOUNG Showcasing work by our 2020 visual art and design graduating students within the Bachelor of Visual Arts, Bachelor of Communication Design, Creative Arts (Honours) and Advanced Diploma of Graphic Design, Ballarat, this exhibition has been curated at the School of Arts Post Office Gallery following our virtual exhibition launch in 2020. Image: Vienna Drysdale Bischard Figure 2, 2020 digital print on archival paper H50 X W35 cm Courtesy the artist
- Description: 11 MAR - 1 APR 2021 Anthea BIDWELL Vienna Drysdale BISCHARD Jessica CHAPLIN Kathryn DRUM Miles FOLEY Tameka HAGUE Clayton KEEFE Angeline KOOT Lauren MATTHEWS Tess MCLOUGHLAN Sarah TAYLOR Brittany TUCKER Ella YOUNG Showcasing work by our 2020 visual art and design graduating students within the Bachelor of Visual Arts, Bachelor of Communication Design, Creative Arts (Honours) and Advanced Diploma of Graphic Design, Ballarat, this exhibition has been curated at the School of Arts Post Office Gallery following our virtual exhibition launch in 2020.