Design and analysis of nano-structured gratings for conversion efficiency improvement in GaAs solar cells
- Authors: Das, Narottam , Islam, Syed
- Date: 2016
- Type: Text , Journal article
- Relation: Energies Vol. 9, no. 9 (2016), p. 1-13
- Full Text:
- Reviewed:
- Description: This paper presents the design and analysis of nano-structured gratings to improve the conversion efficiency in GaAs solar cells by reducing the light reflection losses. A finite-difference time domain (FDTD) simulation tool is used to design and simulate the light reflection losses of the subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures perform as an excellent alternative antireflective (AR) coating due to their capacity to reduce the reflection losses in GaAs solar cells. It allows the gradual change in the refractive index that confirms an excellent AR and the light trapping properties, when compared with the planar thin film structures. The nano-rod structure performs as a single layer AR coating, whereas the triangular (i.e., conical or perfect cone) and parabolic (i.e., trapezoidal/truncated cone) shaped nano-grating structures perform as a multilayer AR coating. The simulation results confirm that the reflection loss of triangular-shaped nano-grating structures having a 300-nm grating height and a 830-nm period is about 2%, which is about 28% less than the flat type substrates. It also found that the intermediate (i.e., trapezoidal and parabolic)-shaped structures, the light reflection loss is lower than the rectangular shaped nano-grating structure, but higher than the triangular shaped nano-grating structure. This analysis confirmed that the triangular shaped nano-gratings are an excellent alternative AR coating for conversion efficiency improvement in GaAs solar cells.
- Authors: Das, Narottam , Islam, Syed
- Date: 2016
- Type: Text , Journal article
- Relation: Energies Vol. 9, no. 9 (2016), p. 1-13
- Full Text:
- Reviewed:
- Description: This paper presents the design and analysis of nano-structured gratings to improve the conversion efficiency in GaAs solar cells by reducing the light reflection losses. A finite-difference time domain (FDTD) simulation tool is used to design and simulate the light reflection losses of the subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures perform as an excellent alternative antireflective (AR) coating due to their capacity to reduce the reflection losses in GaAs solar cells. It allows the gradual change in the refractive index that confirms an excellent AR and the light trapping properties, when compared with the planar thin film structures. The nano-rod structure performs as a single layer AR coating, whereas the triangular (i.e., conical or perfect cone) and parabolic (i.e., trapezoidal/truncated cone) shaped nano-grating structures perform as a multilayer AR coating. The simulation results confirm that the reflection loss of triangular-shaped nano-grating structures having a 300-nm grating height and a 830-nm period is about 2%, which is about 28% less than the flat type substrates. It also found that the intermediate (i.e., trapezoidal and parabolic)-shaped structures, the light reflection loss is lower than the rectangular shaped nano-grating structure, but higher than the triangular shaped nano-grating structure. This analysis confirmed that the triangular shaped nano-gratings are an excellent alternative AR coating for conversion efficiency improvement in GaAs solar cells.
At last count : Engineering undergraduates in 21st Century Australia
- Authors: Dobson, Ian
- Date: 2013
- Type: Text , Journal article
- Relation: World Transactions on Engineering and Technology Education Vol. 10, no. 4 (2013), p. 253-257
- Full Text:
- Reviewed:
- Description: The number of enrolments in undergraduate programmes in engineering has grown at more than the national average this century. The main areas of enrolment growth in Australian higher education have been of women and overseas students, and the latter group has been particularly relevant in the case in engineering. The analysis undertaken for this article is based on statistical data from the ministry responsible for Australia's tertiary education. However, women remain underrepresented in engineering programmes, and there is a risk that the high proportion of overseas students means that Australia is exporting engineering talent at a cost to the development of its own knowledge-intensive labour force. © 2012 WIETE.
- Description: 2003010825
- Authors: Dobson, Ian
- Date: 2013
- Type: Text , Journal article
- Relation: World Transactions on Engineering and Technology Education Vol. 10, no. 4 (2013), p. 253-257
- Full Text:
- Reviewed:
- Description: The number of enrolments in undergraduate programmes in engineering has grown at more than the national average this century. The main areas of enrolment growth in Australian higher education have been of women and overseas students, and the latter group has been particularly relevant in the case in engineering. The analysis undertaken for this article is based on statistical data from the ministry responsible for Australia's tertiary education. However, women remain underrepresented in engineering programmes, and there is a risk that the high proportion of overseas students means that Australia is exporting engineering talent at a cost to the development of its own knowledge-intensive labour force. © 2012 WIETE.
- Description: 2003010825
Understanding safety management system applicability in community sport
- Donaldson, Alex, Borys, David, Finch, Caroline
- Authors: Donaldson, Alex , Borys, David , Finch, Caroline
- Date: 2013
- Type: Text , Journal article
- Relation: Safety Science Vol. 60, no. (2013), p. 95-104
- Relation: http://purl.org/au-research/grants/nhmrc/565907
- Full Text:
- Reviewed:
- Description: Despite recent interest in understanding the implementation context for sports injury prevention interventions, little research attention has been paid to the management structures and processes of community sporting organisations. This study developed expert consensus about the importance of Occupational Health and Safety (OHS) setting-related safety management system (SMS) principles and performance indicators in the context of Australian community sporting organizations, and the feasibility of these organisations meeting the requirements for the SMS performance indicators. Twenty-nine sports injury prevention, community sports administration and OHS SMS experts participated in a three-round online Delphi study by rating the importance of 64 SMS performance indicators categorised under the five principles of Commitment and Policy; Planning; Implementation; Measurement and Evaluation; and Review and Improvement. Overall, consensus agreement - define as rated 'essential' or 'very important' on a five-point scale by ≥75% of the participants in Round 3 - was reached for 57 performance indicators. Ten (15%) performance indicators were rated as 'very difficult' or 'relatively difficult', and six (9%) were rated as 'very easy' or 'relatively easy' on a four-point scale, by ≥75% of participants. This research suggests that the guiding principles and associated performance indicators that underpin OHS safety management systems in the workplace are very relevant and applicable to community sporting organisations in Australia. However, considerable work is required to build organisational capacity to be able to develop and implement meaningfully and useful SMSs to prevent sports injuries in the most common setting in which they occur. © 2013 Elsevier Ltd. Funded by NHMRC.
- Description: 2003011206
- Authors: Donaldson, Alex , Borys, David , Finch, Caroline
- Date: 2013
- Type: Text , Journal article
- Relation: Safety Science Vol. 60, no. (2013), p. 95-104
- Relation: http://purl.org/au-research/grants/nhmrc/565907
- Full Text:
- Reviewed:
- Description: Despite recent interest in understanding the implementation context for sports injury prevention interventions, little research attention has been paid to the management structures and processes of community sporting organisations. This study developed expert consensus about the importance of Occupational Health and Safety (OHS) setting-related safety management system (SMS) principles and performance indicators in the context of Australian community sporting organizations, and the feasibility of these organisations meeting the requirements for the SMS performance indicators. Twenty-nine sports injury prevention, community sports administration and OHS SMS experts participated in a three-round online Delphi study by rating the importance of 64 SMS performance indicators categorised under the five principles of Commitment and Policy; Planning; Implementation; Measurement and Evaluation; and Review and Improvement. Overall, consensus agreement - define as rated 'essential' or 'very important' on a five-point scale by ≥75% of the participants in Round 3 - was reached for 57 performance indicators. Ten (15%) performance indicators were rated as 'very difficult' or 'relatively difficult', and six (9%) were rated as 'very easy' or 'relatively easy' on a four-point scale, by ≥75% of participants. This research suggests that the guiding principles and associated performance indicators that underpin OHS safety management systems in the workplace are very relevant and applicable to community sporting organisations in Australia. However, considerable work is required to build organisational capacity to be able to develop and implement meaningfully and useful SMSs to prevent sports injuries in the most common setting in which they occur. © 2013 Elsevier Ltd. Funded by NHMRC.
- Description: 2003011206
Use of stochastic XFEM in the investigation of heterogeneity effects on the tensile strength of intermediate geotechnical materials
- Dyson, Ashley, Tang, Zhan, Tolooiyan, Ali
- Authors: Dyson, Ashley , Tang, Zhan , Tolooiyan, Ali
- Date: 2018
- Type: Text , Journal article
- Relation: Finite Elements in Analysis and Design Vol. 145, no. (2018), p. 1-9
- Full Text:
- Reviewed:
- Description: The numerical simulation of an Unconfined Expansion Test (UET) is presented with tensile strength fracture criteria assigned by stochastic methods to take into account material heterogeneity. Tests are performed by producing radial cavity expansion models of thinly sliced cylindrical specimens. The introduction of element-wise allocation of fracture parameters generates instances of specimen failure without the requirement of predefined fracture zones, permitting discontinuities to form naturally within zones containing weak strength parameters. The parallel application of an in-house Python scripts and eXtended Finite Element Method (XFEM) facilitates the investigation of heterogeneity effects on the tensile strength of intermediate geotechnical materials.
- Authors: Dyson, Ashley , Tang, Zhan , Tolooiyan, Ali
- Date: 2018
- Type: Text , Journal article
- Relation: Finite Elements in Analysis and Design Vol. 145, no. (2018), p. 1-9
- Full Text:
- Reviewed:
- Description: The numerical simulation of an Unconfined Expansion Test (UET) is presented with tensile strength fracture criteria assigned by stochastic methods to take into account material heterogeneity. Tests are performed by producing radial cavity expansion models of thinly sliced cylindrical specimens. The introduction of element-wise allocation of fracture parameters generates instances of specimen failure without the requirement of predefined fracture zones, permitting discontinuities to form naturally within zones containing weak strength parameters. The parallel application of an in-house Python scripts and eXtended Finite Element Method (XFEM) facilitates the investigation of heterogeneity effects on the tensile strength of intermediate geotechnical materials.
The reach and adoption of a coach-led exercise training programme in community football
- Finch, Caroline, Diamantopoulou, Kathy, Twomey, Dara, Doyle, Tim, Lloyd, David, Young, Warren, Elliot, Bruce
- Authors: Finch, Caroline , Diamantopoulou, Kathy , Twomey, Dara , Doyle, Tim , Lloyd, David , Young, Warren , Elliot, Bruce
- Date: 2013
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine. Vol. 48(8), p.718-723.
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective: To determine the reach and adoption of a coach-led exercise training programme for lower limb injury prevention. Design: Secondary analysis of data from a group-clustered randomised controlled trial. Setting: A periodised exercise training warm-up programme was delivered to players during training sessions over an 8-week preseason (weeks 1–8) and 18-week playing season. Participants: 1564 community Australian football players. Main outcome measurements: Reach, measured weekly, was the number of players who attended training sessions. Adoption was the number of attending players who completed the programme in full, partially or not at all. Reasons for partial or non-participation were recorded. Results: In week 1, 599 players entered the programme; 55% attended 1 training session and 45% attended > 1 session. By week 12, 1540 players were recruited but training attendance (reach) decreased to <50%. When players attended training, the majority adopted the full programme—ranging from 96% (week 1) to above 80% until week 20. The most common reasons for low adoption were players being injured, too sore, being late for training or choosing their own warm-up. Conclusions: The training programme's reach was highest preseason and halved at the playing season's end. However, when players attended training sessions, their adoption was high and remained close to 70% by season end. For sports injury prevention programmes to be fully effective across a season, attention also needs to be given to (1) encouraging players to attend formal training sessions and (2) considering the possibility of some form of programme delivery outside of formal training.
- Authors: Finch, Caroline , Diamantopoulou, Kathy , Twomey, Dara , Doyle, Tim , Lloyd, David , Young, Warren , Elliot, Bruce
- Date: 2013
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine. Vol. 48(8), p.718-723.
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective: To determine the reach and adoption of a coach-led exercise training programme for lower limb injury prevention. Design: Secondary analysis of data from a group-clustered randomised controlled trial. Setting: A periodised exercise training warm-up programme was delivered to players during training sessions over an 8-week preseason (weeks 1–8) and 18-week playing season. Participants: 1564 community Australian football players. Main outcome measurements: Reach, measured weekly, was the number of players who attended training sessions. Adoption was the number of attending players who completed the programme in full, partially or not at all. Reasons for partial or non-participation were recorded. Results: In week 1, 599 players entered the programme; 55% attended 1 training session and 45% attended > 1 session. By week 12, 1540 players were recruited but training attendance (reach) decreased to <50%. When players attended training, the majority adopted the full programme—ranging from 96% (week 1) to above 80% until week 20. The most common reasons for low adoption were players being injured, too sore, being late for training or choosing their own warm-up. Conclusions: The training programme's reach was highest preseason and halved at the playing season's end. However, when players attended training sessions, their adoption was high and remained close to 70% by season end. For sports injury prevention programmes to be fully effective across a season, attention also needs to be given to (1) encouraging players to attend formal training sessions and (2) considering the possibility of some form of programme delivery outside of formal training.
Coding OSICS sports injury diagnoses in epidemiological studies : Does the background of the coder matter?
- Finch, Caroline, Orchard, John, Twomey, Dara, Saleem, Muhammad Saad, Ekegren, Christina, Lloyd, David, Elliott, Bruce
- Authors: Finch, Caroline , Orchard, John , Twomey, Dara , Saleem, Muhammad Saad , Ekegren, Christina , Lloyd, David , Elliott, Bruce
- Date: 2012
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine, Vol.48, p.552-556.
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective: To compare Orchard Sports Injury Classification System (OSICS-10) sports medicine diagnoses assigned by a clinical and non-clinical coder. Design: Assessment of intercoder agreement. Setting: Community Australian football. Participants: 1082 standardised injury surveillance records. Main outcome measurements: Direct comparison of the four-character hierarchical OSICS-10 codes assigned by two independent coders (a sports physician and an epidemiologist). Adjudication by a third coder (biomechanist). Results: The coders agreed on the first character 95% of the time and on the first two characters 86% of the time. They assigned the same four-digit OSICS-10 code for only 46% of the 1082 injuries. The majority of disagreements occurred for the third character; 85% were because one coder assigned a non-specific 'X' code. The sports physician code was deemed correct in 53% of cases and the epidemiologist in 44%. Reasons for disagreement included the physician not using all of the collected information and the epidemiologist lacking specific anatomical knowledge. Conclusions: Sports injury research requires accurate identification and classification of specific injuries and this study found an overall high level of agreement in coding according to OSICS-10. The fact that the majority of the disagreements occurred for the third OSICS character highlights the fact that increasing complexity and diagnostic specificity in injury coding can result in a loss of reliability and demands a high level of anatomical knowledge. Injury report form details need to reflect this level of complexity and data management teams need to include a broad range of expertise. Copyright Article author (or their employer) 2012.
- Authors: Finch, Caroline , Orchard, John , Twomey, Dara , Saleem, Muhammad Saad , Ekegren, Christina , Lloyd, David , Elliott, Bruce
- Date: 2012
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine, Vol.48, p.552-556.
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective: To compare Orchard Sports Injury Classification System (OSICS-10) sports medicine diagnoses assigned by a clinical and non-clinical coder. Design: Assessment of intercoder agreement. Setting: Community Australian football. Participants: 1082 standardised injury surveillance records. Main outcome measurements: Direct comparison of the four-character hierarchical OSICS-10 codes assigned by two independent coders (a sports physician and an epidemiologist). Adjudication by a third coder (biomechanist). Results: The coders agreed on the first character 95% of the time and on the first two characters 86% of the time. They assigned the same four-digit OSICS-10 code for only 46% of the 1082 injuries. The majority of disagreements occurred for the third character; 85% were because one coder assigned a non-specific 'X' code. The sports physician code was deemed correct in 53% of cases and the epidemiologist in 44%. Reasons for disagreement included the physician not using all of the collected information and the epidemiologist lacking specific anatomical knowledge. Conclusions: Sports injury research requires accurate identification and classification of specific injuries and this study found an overall high level of agreement in coding according to OSICS-10. The fact that the majority of the disagreements occurred for the third OSICS character highlights the fact that increasing complexity and diagnostic specificity in injury coding can result in a loss of reliability and demands a high level of anatomical knowledge. Injury report form details need to reflect this level of complexity and data management teams need to include a broad range of expertise. Copyright Article author (or their employer) 2012.
What do community football players think about different exercise-training programmes? Implications for the delivery of lower limb injury prevention programmes
- Finch, Caroline, Doyle, Tim, Dempsey, Alasdair, Elliott, Bruce, Twomey, Dara, White, Peta, Diamantopoulou, Kathy, Young, Warren, Lloyd, David
- Authors: Finch, Caroline , Doyle, Tim , Dempsey, Alasdair , Elliott, Bruce , Twomey, Dara , White, Peta , Diamantopoulou, Kathy , Young, Warren , Lloyd, David
- Date: 2014
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 48, no. 8 (2014), p.702-707
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Background: Players are the targeted end-users and beneficiaries of exercise-training programmes implemented during coach-led training sessions, and the success of programmes depends upon their active participation. Two variants of an exercise-training programme were incorporated into the regular training schedules of 40 community Australian Football teams, over two seasons. One variant replicated common training practices, while the second was an evidence-based programme to alter biomechanical and neuromuscular factors related to risk of knee injuries. This paper describes the structure of the implemented programmes and compares players’ end-of-season views about the programme variants. Methods: This study was nested within a larger group-clustered randomised controlled trial of the effectiveness of two exercise-training programmes (control and neuromuscular control (NMC)) for preventing knee injuries. A post-season self-report survey, derived from Health Belief Model constructs, included questions to obtain players’ views about the benefits and physical challenges of the programme in which they participated. Results: Compared with control players, those who participated in the NMC programme found it to be less physically challenging but more enjoyable and potentially of more benefit. Suggestions from players about potential improvements to the training programme and its future implementation included reducing duration, increasing range of drills/exercises and promoting its injury prevention and other benefits to players. Conclusions: Players provide valuable feedback about the content and focus of implemented exercise-training programmes, that will directly inform the delivery of similar, or more successful, programmes in the future.
- Authors: Finch, Caroline , Doyle, Tim , Dempsey, Alasdair , Elliott, Bruce , Twomey, Dara , White, Peta , Diamantopoulou, Kathy , Young, Warren , Lloyd, David
- Date: 2014
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 48, no. 8 (2014), p.702-707
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Background: Players are the targeted end-users and beneficiaries of exercise-training programmes implemented during coach-led training sessions, and the success of programmes depends upon their active participation. Two variants of an exercise-training programme were incorporated into the regular training schedules of 40 community Australian Football teams, over two seasons. One variant replicated common training practices, while the second was an evidence-based programme to alter biomechanical and neuromuscular factors related to risk of knee injuries. This paper describes the structure of the implemented programmes and compares players’ end-of-season views about the programme variants. Methods: This study was nested within a larger group-clustered randomised controlled trial of the effectiveness of two exercise-training programmes (control and neuromuscular control (NMC)) for preventing knee injuries. A post-season self-report survey, derived from Health Belief Model constructs, included questions to obtain players’ views about the benefits and physical challenges of the programme in which they participated. Results: Compared with control players, those who participated in the NMC programme found it to be less physically challenging but more enjoyable and potentially of more benefit. Suggestions from players about potential improvements to the training programme and its future implementation included reducing duration, increasing range of drills/exercises and promoting its injury prevention and other benefits to players. Conclusions: Players provide valuable feedback about the content and focus of implemented exercise-training programmes, that will directly inform the delivery of similar, or more successful, programmes in the future.
Implementing an exercise-training programme to prevent lower-limb injuries : Considerations for the development of a randomised controlled trial intervention delivery plan
- Finch, Caroline, White, Peta, Twomey, Dara, Ullah, Shahid
- Authors: Finch, Caroline , White, Peta , Twomey, Dara , Ullah, Shahid
- Date: 2011
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 45, no. 10 (2011), p. 791-796
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective To identify important considerations for the delivery of an exercise training intervention in a randomised controlled trial to maximise subsequent participation in that randomised controlled trial and intervention uptake. Design A cross-sectional survey, with a theoretical basis derived from the Health Belief Model (HBM) and the Reach, Efficacy/Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) framework. Participants 374 male senior Australian Football players, aged 17-38 years. Main outcome measurements Beliefs about lowerlimb injury causation/prevention, and the relative value of exercise training for performance and injury prevention. The data are interpreted within HBM constructs and implications for subsequent intervention implementation considered within the RE-AIM framework. Ordinal logistic regression compared belief scores across player characteristics. Results 74.4% of players agreed that doing specific exercises during training would reduce their risk of lower-limb injury and would be willing to undertake them. However, 64.1% agreed that training should focus more on improving game performance than injury prevention. Younger players (both in terms of age and playing experience) generally had more positive views. Players were most supportive of kicking (98.9%) and ball-handling (97.0%) skills for performance and warm-up runs and cool-downs (both 91.5%) for injury prevention. Fewer than three-quarters of all players believed that balance (69.2%), landing (71.3%) or cutting/stepping (72.8) training had injury-prevention benefits. Conclusions Delivery of future exercise training programmes for injury prevention aimed at these players should be implemented as part of routine football activities and integrated with those as standard practice, as a means of associating them with training benefits for this sport.
- Authors: Finch, Caroline , White, Peta , Twomey, Dara , Ullah, Shahid
- Date: 2011
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 45, no. 10 (2011), p. 791-796
- Relation: http://purl.org/au-research/grants/nhmrc/565900
- Full Text:
- Reviewed:
- Description: Objective To identify important considerations for the delivery of an exercise training intervention in a randomised controlled trial to maximise subsequent participation in that randomised controlled trial and intervention uptake. Design A cross-sectional survey, with a theoretical basis derived from the Health Belief Model (HBM) and the Reach, Efficacy/Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) framework. Participants 374 male senior Australian Football players, aged 17-38 years. Main outcome measurements Beliefs about lowerlimb injury causation/prevention, and the relative value of exercise training for performance and injury prevention. The data are interpreted within HBM constructs and implications for subsequent intervention implementation considered within the RE-AIM framework. Ordinal logistic regression compared belief scores across player characteristics. Results 74.4% of players agreed that doing specific exercises during training would reduce their risk of lower-limb injury and would be willing to undertake them. However, 64.1% agreed that training should focus more on improving game performance than injury prevention. Younger players (both in terms of age and playing experience) generally had more positive views. Players were most supportive of kicking (98.9%) and ball-handling (97.0%) skills for performance and warm-up runs and cool-downs (both 91.5%) for injury prevention. Fewer than three-quarters of all players believed that balance (69.2%), landing (71.3%) or cutting/stepping (72.8) training had injury-prevention benefits. Conclusions Delivery of future exercise training programmes for injury prevention aimed at these players should be implemented as part of routine football activities and integrated with those as standard practice, as a means of associating them with training benefits for this sport.
Controlled ecological evaluation of an implemented exercise-training programme to prevent lower limb injuries in sport : Population-level trends in hospital-treated injuries
- Finch, Caroline, Gray, Shannon, Akram, Muhammad, Donaldson, Alex, Lloyd, David, Cook, Jill
- Authors: Finch, Caroline , Gray, Shannon , Akram, Muhammad , Donaldson, Alex , Lloyd, David , Cook, Jill
- Date: 2019
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 53, no. 8 (2019), p. 487-492
- Full Text:
- Reviewed:
- Description: Objective Exercise-training programmes have reduced lower limb injuries in trials, but their population-level effectiveness has not been reported in implementation trials. This study aimed to demonstrate that routinely collected hospital data can be used to evaluate population-level programme effectiveness. Method A controlled ecological design was used to evaluate the effect of FootyFirst, an exercise-training programme, on the number of hospital-treated lower limb injuries sustained by males aged 16-50 years while participating in community-level Australian Football. FootyFirst was implemented with a € support' (FootyFirst+S) or a € without support' (FootyFirst+NS) in different geographic regions of Victoria, Australia: 22 clubs in region 1: FootyFirst+S in 2012/2013; 25 clubs in region 2: FootyFirst+NS in 2012/2013; 31 clubs region 3: control in 2012, FootyFirst+S in 2013. Interrupted time-series analysis compared injury counts across regions and against trends in the rest of Victoria. Results After 1 year of FootyFirst+S, there was a non-statistically significant decline in the number of lower limb injuries in region 1 (2012) and region 3 (2013); this was not maintained after 2 years in region 1. Compared with before FootyFirst in 2006-2011, injury count changes at the end of 2013 were: region 1: 20.0% reduction (after 2 years support); region 2: 21.5% increase (after 2 years without support); region 3: 21.8% increase (after first year no programme, second year programme with support); rest of Victoria: 12.6% increase. Conclusion Ecological analyses using routinely collected hospital data show promise as the basis of population-level programme evaluation. The implementation and sustainability of sports injury prevention programmes at the population-level remains challenging.
- Authors: Finch, Caroline , Gray, Shannon , Akram, Muhammad , Donaldson, Alex , Lloyd, David , Cook, Jill
- Date: 2019
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 53, no. 8 (2019), p. 487-492
- Full Text:
- Reviewed:
- Description: Objective Exercise-training programmes have reduced lower limb injuries in trials, but their population-level effectiveness has not been reported in implementation trials. This study aimed to demonstrate that routinely collected hospital data can be used to evaluate population-level programme effectiveness. Method A controlled ecological design was used to evaluate the effect of FootyFirst, an exercise-training programme, on the number of hospital-treated lower limb injuries sustained by males aged 16-50 years while participating in community-level Australian Football. FootyFirst was implemented with a € support' (FootyFirst+S) or a € without support' (FootyFirst+NS) in different geographic regions of Victoria, Australia: 22 clubs in region 1: FootyFirst+S in 2012/2013; 25 clubs in region 2: FootyFirst+NS in 2012/2013; 31 clubs region 3: control in 2012, FootyFirst+S in 2013. Interrupted time-series analysis compared injury counts across regions and against trends in the rest of Victoria. Results After 1 year of FootyFirst+S, there was a non-statistically significant decline in the number of lower limb injuries in region 1 (2012) and region 3 (2013); this was not maintained after 2 years in region 1. Compared with before FootyFirst in 2006-2011, injury count changes at the end of 2013 were: region 1: 20.0% reduction (after 2 years support); region 2: 21.5% increase (after 2 years without support); region 3: 21.8% increase (after first year no programme, second year programme with support); rest of Victoria: 12.6% increase. Conclusion Ecological analyses using routinely collected hospital data show promise as the basis of population-level programme evaluation. The implementation and sustainability of sports injury prevention programmes at the population-level remains challenging.
On topology optimization and canonical duality method
- Authors: Gao, David
- Date: 2018
- Type: Text , Journal article
- Relation: Computer Methods in Applied Mechanics and Engineering Vol. 341, no. (2018), p. 249-277
- Full Text:
- Reviewed:
- Description: Topology optimization for general materials is correctly formulated as a bi-level knapsack problem, which is considered to be NP-hard in global optimization and computer science. By using canonical duality theory (CDT) developed by the author, the linear knapsack problem can be solved analytically to obtain global optimal solution at each design iteration. Both uniqueness, existence, and NP-hardness are discussed. The novel CDT method for general topology optimization is refined and tested by both 2-D and 3-D benchmark problems. Numerical results show that without using filter and any other artificial technique, the CDT method can produce exactly 0-1 optimal density distribution with almost no checkerboard pattern. Its performance and novelty are compared with the popular SIMP and BESO approaches. Additionally, some mathematical and conceptual mistakes in literature are explicitly addressed. A brief review on the canonical duality theory for modeling multi-scale complex systems and for solving general nonconvex/discrete problems are given in Appendix. This paper demonstrates a simple truth: elegant designs come from correct model and theory. © 2018
- Authors: Gao, David
- Date: 2018
- Type: Text , Journal article
- Relation: Computer Methods in Applied Mechanics and Engineering Vol. 341, no. (2018), p. 249-277
- Full Text:
- Reviewed:
- Description: Topology optimization for general materials is correctly formulated as a bi-level knapsack problem, which is considered to be NP-hard in global optimization and computer science. By using canonical duality theory (CDT) developed by the author, the linear knapsack problem can be solved analytically to obtain global optimal solution at each design iteration. Both uniqueness, existence, and NP-hardness are discussed. The novel CDT method for general topology optimization is refined and tested by both 2-D and 3-D benchmark problems. Numerical results show that without using filter and any other artificial technique, the CDT method can produce exactly 0-1 optimal density distribution with almost no checkerboard pattern. Its performance and novelty are compared with the popular SIMP and BESO approaches. Additionally, some mathematical and conceptual mistakes in literature are explicitly addressed. A brief review on the canonical duality theory for modeling multi-scale complex systems and for solving general nonconvex/discrete problems are given in Appendix. This paper demonstrates a simple truth: elegant designs come from correct model and theory. © 2018
Canonical duality theory and algorithm for solving bilevel knapsack problems with applications
- Authors: Gao, David
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Transactions on Systems, Man, and Cybernetics: Systems Vol. 51, no. 2 (2021), p. 893-904
- Full Text:
- Reviewed:
- Description: A novel canonical duality theory (CDT) is presented for solving general bilevel mixed integer nonlinear optimization governed by linear and quadratic knapsack problems. It shows that the challenging knapsack problems can be solved analytically in term of their canonical dual solutions. The existence and uniqueness of these analytical solutions are proved. NP-hardness of the knapsack problems is discussed. A powerful CDT algorithm combined with an alternative iteration and a volume reduction method is proposed for solving the NP-hard bilevel knapsack problems. Application is illustrated by benchmark problems in optimal topology design. The performance and novelty of the proposed method are compared with the popular commercial codes. © 2013 IEEE.
- Authors: Gao, David
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE Transactions on Systems, Man, and Cybernetics: Systems Vol. 51, no. 2 (2021), p. 893-904
- Full Text:
- Reviewed:
- Description: A novel canonical duality theory (CDT) is presented for solving general bilevel mixed integer nonlinear optimization governed by linear and quadratic knapsack problems. It shows that the challenging knapsack problems can be solved analytically in term of their canonical dual solutions. The existence and uniqueness of these analytical solutions are proved. NP-hardness of the knapsack problems is discussed. A powerful CDT algorithm combined with an alternative iteration and a volume reduction method is proposed for solving the NP-hard bilevel knapsack problems. Application is illustrated by benchmark problems in optimal topology design. The performance and novelty of the proposed method are compared with the popular commercial codes. © 2013 IEEE.
Techno-economic evaluation of amine-reclamation technologies and combined CO2/SO2 capture for Australian coal-fired plants
- Garg, Bharti, Haque, Nawshad, Cousins, Ashleigh, Pearson, Pauline, Verheyen, Vincent, Feron, Paul
- Authors: Garg, Bharti , Haque, Nawshad , Cousins, Ashleigh , Pearson, Pauline , Verheyen, Vincent , Feron, Paul
- Date: 2020
- Type: Text , Journal article
- Relation: International Journal of Greenhouse Gas Control Vol. 98, no. (2020), p.
- Full Text:
- Reviewed:
- Description: CSIRO's patented CS-Cap process aims at reducing the costs of amine-based post-combustion capture by combining SO2 and CO2 capture using one absorbent in a single absorber column. By avoiding the need for a separate flue gas desulfurization unit, the process offers potential savings for power plants requiring CO2 capture. High-level cost estimates based on lab and pilot data are presented for two amine reclamation techniques i.e. thermal reclamation and reactive crystallisation. Only regeneration via reactive crystallisation reduces CS-Cap costs below base case FGD/SCR-PCC. Cost estimations suggest a potential reduction of 38–44% in the total plant cost when using the CS-Cap process compared to base case. However, the amine reclaimer operating cost governs the overall cost of the CS-Cap process and is highly sensitive to sulfur content. A 50% reduction is observed when SO2 levels reduce from 700 to 200 ppm. Comparing levelised cost of electricity and CO2 avoided costs for CS-Cap against our base case, low sulfur brown coal has a slight (5–7%) cost advantage; however, confirmation requires pilot data on amine recovery. © 2020
- Authors: Garg, Bharti , Haque, Nawshad , Cousins, Ashleigh , Pearson, Pauline , Verheyen, Vincent , Feron, Paul
- Date: 2020
- Type: Text , Journal article
- Relation: International Journal of Greenhouse Gas Control Vol. 98, no. (2020), p.
- Full Text:
- Reviewed:
- Description: CSIRO's patented CS-Cap process aims at reducing the costs of amine-based post-combustion capture by combining SO2 and CO2 capture using one absorbent in a single absorber column. By avoiding the need for a separate flue gas desulfurization unit, the process offers potential savings for power plants requiring CO2 capture. High-level cost estimates based on lab and pilot data are presented for two amine reclamation techniques i.e. thermal reclamation and reactive crystallisation. Only regeneration via reactive crystallisation reduces CS-Cap costs below base case FGD/SCR-PCC. Cost estimations suggest a potential reduction of 38–44% in the total plant cost when using the CS-Cap process compared to base case. However, the amine reclaimer operating cost governs the overall cost of the CS-Cap process and is highly sensitive to sulfur content. A 50% reduction is observed when SO2 levels reduce from 700 to 200 ppm. Comparing levelised cost of electricity and CO2 avoided costs for CS-Cap against our base case, low sulfur brown coal has a slight (5–7%) cost advantage; however, confirmation requires pilot data on amine recovery. © 2020
Influence of silica nano-additives on performance and emission characteristics of soybean biodiesel fuelled diesel engine
- Gavhane, R., Kate, A., Soudagar, Manzoore, Wakchaure, V., Shahabuddin, M.
- Authors: Gavhane, R. , Kate, A. , Soudagar, Manzoore , Wakchaure, V. , Shahabuddin, M.
- Date: 2021
- Type: Text , Journal article
- Relation: Energies Vol. 14, no. 5 (Mar 2021), p. 16
- Full Text:
- Reviewed:
- Description: The present study examines the effect of silicon dioxide (SiO2) nano-additives on the performance and emission characteristics of a diesel engine fuelled with soybean biodiesel. Soybean biofuel was prepared using the transesterification process. The morphology of nano-additives was studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The Ultrasonication process was used for the homogeneous blending of nano-additives with biodiesel, while surfactant was used for the stabilisation of nano-additives. The physicochemical properties of pure and blended fuel samples were measured as per ASTM standards. The performance and emissions characteristics of different fuel samples were measured at different loading conditions. It was found that the brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) increased by 3.48-6.39% and 5.81-9.88%, respectively, with the addition of SiO2 nano-additives. The carbon monoxide (CO), hydrocarbon (HC) and smoke emissions for nano-additive added blends were decreased by 1.9-17.5%, 20.56-27.5% and 10.16-23.54% compared to SBME25 fuel blends. *Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “M. Shahabuddin” is provided in this record**
- Authors: Gavhane, R. , Kate, A. , Soudagar, Manzoore , Wakchaure, V. , Shahabuddin, M.
- Date: 2021
- Type: Text , Journal article
- Relation: Energies Vol. 14, no. 5 (Mar 2021), p. 16
- Full Text:
- Reviewed:
- Description: The present study examines the effect of silicon dioxide (SiO2) nano-additives on the performance and emission characteristics of a diesel engine fuelled with soybean biodiesel. Soybean biofuel was prepared using the transesterification process. The morphology of nano-additives was studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The Ultrasonication process was used for the homogeneous blending of nano-additives with biodiesel, while surfactant was used for the stabilisation of nano-additives. The physicochemical properties of pure and blended fuel samples were measured as per ASTM standards. The performance and emissions characteristics of different fuel samples were measured at different loading conditions. It was found that the brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) increased by 3.48-6.39% and 5.81-9.88%, respectively, with the addition of SiO2 nano-additives. The carbon monoxide (CO), hydrocarbon (HC) and smoke emissions for nano-additive added blends were decreased by 1.9-17.5%, 20.56-27.5% and 10.16-23.54% compared to SBME25 fuel blends. *Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “M. Shahabuddin” is provided in this record**
Technical evaluation of post-combustion CO2 capture and hydrogen production industrial symbiosis
- Ghayur, Adeel, Verheyen, Vincent
- Authors: Ghayur, Adeel , Verheyen, Vincent
- Date: 2018
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 43, no. 30 (2018), p. 13852-13859
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- Description: The aim of this study is to develop an industrial ecosystem whereby wastes/products from a Post-combustion CO2 Capture (PCC) plant are utilised in a hydrogen biorefinery. Subsequently, five hydrogen biorefinery models are developed that use PCC's model amine i.e. monoethanolamine (MEA) as a nitrogen source during microbial hydrogen production and CO2 as a process chemical. Technical evaluations of the five case models are carried out to identify the ones that maximise value by multiproduct generation from biomass and fulfil total/partial parasitic energy demand. The case meeting these criteria, produces 3.1t of succinylated lignin adhesive, 4.9t of dry compost and 2744 kWh of electricity from 10t (dry) of sawdust feedstock, daily. Its daily power and heat duties stand at 3906 kWh and 52.1 GJ respectively. Simulations also demonstrate biohydrogen's potential as an energy storage vector for peak/backup power with an annual 1001.4 MWh of power storage capacity from 10t/d feedstock. © 2018 Hydrogen Energy Publications LLC
- Authors: Ghayur, Adeel , Verheyen, Vincent
- Date: 2018
- Type: Text , Journal article
- Relation: International Journal of Hydrogen Energy Vol. 43, no. 30 (2018), p. 13852-13859
- Full Text:
- Reviewed:
- Description: The aim of this study is to develop an industrial ecosystem whereby wastes/products from a Post-combustion CO2 Capture (PCC) plant are utilised in a hydrogen biorefinery. Subsequently, five hydrogen biorefinery models are developed that use PCC's model amine i.e. monoethanolamine (MEA) as a nitrogen source during microbial hydrogen production and CO2 as a process chemical. Technical evaluations of the five case models are carried out to identify the ones that maximise value by multiproduct generation from biomass and fulfil total/partial parasitic energy demand. The case meeting these criteria, produces 3.1t of succinylated lignin adhesive, 4.9t of dry compost and 2744 kWh of electricity from 10t (dry) of sawdust feedstock, daily. Its daily power and heat duties stand at 3906 kWh and 52.1 GJ respectively. Simulations also demonstrate biohydrogen's potential as an energy storage vector for peak/backup power with an annual 1001.4 MWh of power storage capacity from 10t/d feedstock. © 2018 Hydrogen Energy Publications LLC
Working to rule or working safely? Part 2 : The management of safety rules and procedures
- Authors: Hale, Andrew , Borys, David
- Date: 2012
- Type: Text , Journal article
- Relation: Safety Science Vol.55, no. (2012), p.54-59
- Full Text:
- Reviewed:
- Description: Part 1, the companion paper to this paper () reviews the literature from 1986 on the management of those safety rules and procedures which relate to the workplace level in organisations. It contrasts two different paradigms of how work rules and their development and use are perceived and managed. The first is a top-down classical, rational approach in which rules are seen as static, comprehensive limits of freedom of choice, imposed on operators at the sharp end and violations are seen as negative behaviour to be suppressed. The second is a bottom-up constructivist view of rules as dynamic, local, situated constructions of operators as experts, where competence is seen to a great extent as the ability to adapt rules to the diversity of reality. That paper explores the research underlying and illustrating these two paradigms. In this second paper we draw on that literature study to propose a framework of rule management which attempts to draw the lessons from both paradigms. It places the monitoring and adaptation of rules central to its management process and emphasises the need for participation of the intended rule followers in the processes of rule-making, but more importantly in keeping those rules alive and up to date in a process of regular and explicit dialogue with first-line supervision, and through them with the technical, safety and legal experts on the system functioning. The framework is proposed for testing in the field as a benchmark for good practice. © 2012 Elsevier Ltd. All rights reserved.
- Authors: Hale, Andrew , Borys, David
- Date: 2012
- Type: Text , Journal article
- Relation: Safety Science Vol.55, no. (2012), p.54-59
- Full Text:
- Reviewed:
- Description: Part 1, the companion paper to this paper () reviews the literature from 1986 on the management of those safety rules and procedures which relate to the workplace level in organisations. It contrasts two different paradigms of how work rules and their development and use are perceived and managed. The first is a top-down classical, rational approach in which rules are seen as static, comprehensive limits of freedom of choice, imposed on operators at the sharp end and violations are seen as negative behaviour to be suppressed. The second is a bottom-up constructivist view of rules as dynamic, local, situated constructions of operators as experts, where competence is seen to a great extent as the ability to adapt rules to the diversity of reality. That paper explores the research underlying and illustrating these two paradigms. In this second paper we draw on that literature study to propose a framework of rule management which attempts to draw the lessons from both paradigms. It places the monitoring and adaptation of rules central to its management process and emphasises the need for participation of the intended rule followers in the processes of rule-making, but more importantly in keeping those rules alive and up to date in a process of regular and explicit dialogue with first-line supervision, and through them with the technical, safety and legal experts on the system functioning. The framework is proposed for testing in the field as a benchmark for good practice. © 2012 Elsevier Ltd. All rights reserved.
Working to rule, or working safely? Part 1 : A state of the art review
- Authors: Hale, Andrew , Borys, David
- Date: 2012
- Type: Text , Journal article
- Relation: Safety Science Vol.55, no. June (2013), p.207-221
- Full Text:
- Reviewed:
- Description: The paper reviews the literature from 1986 on the management of those safety rules and procedures which relate to the workplace level in organisations. It contrasts two different paradigms of how rules and their development and use are perceived and managed. The first is a top-down classical, rational approach in which rules are seen as static, comprehensive limits of freedom of choice, imposed on operators at the sharp end and violations are seen as negative behaviour to be suppressed. The second is a bottom-up constructivist view of rules as dynamic, local, situated constructions of operators as experts, where competence is seen to a great extent as the ability to adapt rules to the diversity of reality. The paper explores the research underlying and illustrating these two paradigms, drawn from psychology, sociology and ethnography, organisational studies and behavioural economics. In a separate paper following on from this review (Hale and Borys, this issue http://www.sciencedirect.com/science/article/pii/S0925753512001312#b0285) the authors propose a framework of rule management which attempts to draw the lessons from both paradigms. It places the monitoring and adaptation of rules central to its management process. © 2012 Elsevier Ltd. All rights reserved.
- Authors: Hale, Andrew , Borys, David
- Date: 2012
- Type: Text , Journal article
- Relation: Safety Science Vol.55, no. June (2013), p.207-221
- Full Text:
- Reviewed:
- Description: The paper reviews the literature from 1986 on the management of those safety rules and procedures which relate to the workplace level in organisations. It contrasts two different paradigms of how rules and their development and use are perceived and managed. The first is a top-down classical, rational approach in which rules are seen as static, comprehensive limits of freedom of choice, imposed on operators at the sharp end and violations are seen as negative behaviour to be suppressed. The second is a bottom-up constructivist view of rules as dynamic, local, situated constructions of operators as experts, where competence is seen to a great extent as the ability to adapt rules to the diversity of reality. The paper explores the research underlying and illustrating these two paradigms, drawn from psychology, sociology and ethnography, organisational studies and behavioural economics. In a separate paper following on from this review (Hale and Borys, this issue http://www.sciencedirect.com/science/article/pii/S0925753512001312#b0285) the authors propose a framework of rule management which attempts to draw the lessons from both paradigms. It places the monitoring and adaptation of rules central to its management process. © 2012 Elsevier Ltd. All rights reserved.
Concepts of accident causation and their role in safe design among engineering students
- Hall, Stephen, Culvenor, John, Cowley, Stephen, Else, Dennis
- Authors: Hall, Stephen , Culvenor, John , Cowley, Stephen , Else, Dennis
- Date: 2007
- Type: Text , Conference paper
- Relation: Paper presented at 18th conference of the Australasian Association for Engineering Education, Melbourne, Victoria : 9th-13th December 2007
- Full Text:
- Description: Safe design is a strong theme at present in Australia. To ‘eliminate hazards at the design stage’ is one of the five national priorities set out by the National OHS Strategy. The Australian Safety and Compensation Council have recently released both a guideline for safe design and an engineering education package. Safe design is not only about engineering decisions. Engineers are however an important group. This paper reports on a survey to evaluate perceptions of student engineers on topics relevant to the advancement of safe design including perceptions of: control versus fatalism; accident causation; and perceptions of the role played by engineers.
- Description: 2003004787
- Authors: Hall, Stephen , Culvenor, John , Cowley, Stephen , Else, Dennis
- Date: 2007
- Type: Text , Conference paper
- Relation: Paper presented at 18th conference of the Australasian Association for Engineering Education, Melbourne, Victoria : 9th-13th December 2007
- Full Text:
- Description: Safe design is a strong theme at present in Australia. To ‘eliminate hazards at the design stage’ is one of the five national priorities set out by the National OHS Strategy. The Australian Safety and Compensation Council have recently released both a guideline for safe design and an engineering education package. Safe design is not only about engineering decisions. Engineers are however an important group. This paper reports on a survey to evaluate perceptions of student engineers on topics relevant to the advancement of safe design including perceptions of: control versus fatalism; accident causation; and perceptions of the role played by engineers.
- Description: 2003004787
A new cascaded multilevel inverter topology with galvanic isolation
- Hasan, Mubashwar, Abu-Siada, Ahmed, Islam, Syed, Dahidah, Mohamed
- Authors: Hasan, Mubashwar , Abu-Siada, Ahmed , Islam, Syed , Dahidah, Mohamed
- Date: 2018
- Type: Text , Journal article
- Relation: IEEE Transactions on Industry Applications Vol. 54, no. 4 (2018), p. 3463-3472
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- Description: IEEE This paper presents a new compact three-phase cascaded multilevel inverter (CMLI) topology with reduced device count and high frequency magnetic link. The proposed topology overcomes the predominant limitation of separate DC power supplies, which CMLI always require. The high frequency magnetic link also provides a galvanic isolation between the input and output sides of the inverter, which is essential for various grid-connected applications. The proposed topology utilizes an asymmetric inverter configuration that consists of cascaded H-bridge cells and a conventional three-phase two-level inverter. A toroidal core is employed for the high frequency magnetic link to ensure compact size and high-power density. Compared with counterpart CMLI topologies available in the literatures, the proposed inverter has the advantage of utilizing the least number of power electronic components without compromising the overall performance, particularly when a high number of output voltage levels is required. The feasibility of the proposed inverter is confirmed through extensive simulation and experimentally validated studies.
- Authors: Hasan, Mubashwar , Abu-Siada, Ahmed , Islam, Syed , Dahidah, Mohamed
- Date: 2018
- Type: Text , Journal article
- Relation: IEEE Transactions on Industry Applications Vol. 54, no. 4 (2018), p. 3463-3472
- Full Text:
- Reviewed:
- Description: IEEE This paper presents a new compact three-phase cascaded multilevel inverter (CMLI) topology with reduced device count and high frequency magnetic link. The proposed topology overcomes the predominant limitation of separate DC power supplies, which CMLI always require. The high frequency magnetic link also provides a galvanic isolation between the input and output sides of the inverter, which is essential for various grid-connected applications. The proposed topology utilizes an asymmetric inverter configuration that consists of cascaded H-bridge cells and a conventional three-phase two-level inverter. A toroidal core is employed for the high frequency magnetic link to ensure compact size and high-power density. Compared with counterpart CMLI topologies available in the literatures, the proposed inverter has the advantage of utilizing the least number of power electronic components without compromising the overall performance, particularly when a high number of output voltage levels is required. The feasibility of the proposed inverter is confirmed through extensive simulation and experimentally validated studies.
A novel concept for three-phase cascaded multilevel inverter topologies
- Hasan, Mubashwar, Abu-Siada, Ahmed, Islam, Syed, Muyeen, S.
- Authors: Hasan, Mubashwar , Abu-Siada, Ahmed , Islam, Syed , Muyeen, S.
- Date: 2018
- Type: Text , Journal article
- Relation: Energies Vol. 11, no. 2 (2018), p. 1-16
- Full Text:
- Reviewed:
- Description: One of the key challenges in multilevel inverters (MLIs) design is to reduce the number of components used in the implementation while maximising the number of output voltage levels. This paper proposes a new concept that facilitates a device count reduction technique of existing cascaded MLIs. Moreover, the proposed concept can be utilised to extend existing single phase cascaded MLI topologies to three-phase structure without tripling the number of semiconductor components and input dc-supplies as per the current practice. The new generalized concept involves two stages; namely, cascaded stage and phase generator stage. The phase generator stage is a combination of a conventional three-phase two level inverter and three bi-directional switches while the cascaded stage can employ any existing cascaded topology. A laboratory prototype model is built and extensive experimental analyses are conducted to validate the feasibility of the proposed cascaded MLI concept.
- Authors: Hasan, Mubashwar , Abu-Siada, Ahmed , Islam, Syed , Muyeen, S.
- Date: 2018
- Type: Text , Journal article
- Relation: Energies Vol. 11, no. 2 (2018), p. 1-16
- Full Text:
- Reviewed:
- Description: One of the key challenges in multilevel inverters (MLIs) design is to reduce the number of components used in the implementation while maximising the number of output voltage levels. This paper proposes a new concept that facilitates a device count reduction technique of existing cascaded MLIs. Moreover, the proposed concept can be utilised to extend existing single phase cascaded MLI topologies to three-phase structure without tripling the number of semiconductor components and input dc-supplies as per the current practice. The new generalized concept involves two stages; namely, cascaded stage and phase generator stage. The phase generator stage is a combination of a conventional three-phase two level inverter and three bi-directional switches while the cascaded stage can employ any existing cascaded topology. A laboratory prototype model is built and extensive experimental analyses are conducted to validate the feasibility of the proposed cascaded MLI concept.
A comprehensive spectrum trading scheme based on market competition, reputation and buyer specific requirements
- Hassan, Md Rakib, Karmakar, Gour, Kamruzzaman, Joarder, Srinivasan, Bala
- Authors: Hassan, Md Rakib , Karmakar, Gour , Kamruzzaman, Joarder , Srinivasan, Bala
- Date: 2015
- Type: Text , Journal article
- Relation: Computer Networks Vol. 84, no. (2015), p. 17-31
- Full Text:
- Reviewed:
- Description: In the exclusive-use model of spectrum trading, cognitive radio devices or secondary users can buy spectrum resources from licensed users or primary users for a short or long period of time. Considering such spectrum access, a trading model is introduced where a buyer can select a set of candidate sellers based on their reputation and their offers in fulfilling its requirements, namely, offered signal quality, contract duration, coverage and bandwidth. Similarly, a seller can assess a buyer as a potential trading partner considering the buyer's reliability, which the seller can derive from the buyer's reputation and financial profile. In our scheme, seller reputation or buyer reliability can be either obtained from a reputation brokerage service, if one exists, or calculated using our model. Since in a competitive market, the price of a seller depends on that of other sellers, game theory is used to model the competition among multiple sellers. An optimization technique is used by a buyer to select the best seller(s) and optimize purchase to maximize its utility. This may result in buying from multiple sellers of certain amount of bandwidth from each, depending on price and meeting requirements and budget constraints. Stability of the model is analyzed and performance evaluation shows that it benefits sellers and buyers in terms of profit and throughput, respectively. © 2015 Elsevier B.V. All rights reserved.
- Authors: Hassan, Md Rakib , Karmakar, Gour , Kamruzzaman, Joarder , Srinivasan, Bala
- Date: 2015
- Type: Text , Journal article
- Relation: Computer Networks Vol. 84, no. (2015), p. 17-31
- Full Text:
- Reviewed:
- Description: In the exclusive-use model of spectrum trading, cognitive radio devices or secondary users can buy spectrum resources from licensed users or primary users for a short or long period of time. Considering such spectrum access, a trading model is introduced where a buyer can select a set of candidate sellers based on their reputation and their offers in fulfilling its requirements, namely, offered signal quality, contract duration, coverage and bandwidth. Similarly, a seller can assess a buyer as a potential trading partner considering the buyer's reliability, which the seller can derive from the buyer's reputation and financial profile. In our scheme, seller reputation or buyer reliability can be either obtained from a reputation brokerage service, if one exists, or calculated using our model. Since in a competitive market, the price of a seller depends on that of other sellers, game theory is used to model the competition among multiple sellers. An optimization technique is used by a buyer to select the best seller(s) and optimize purchase to maximize its utility. This may result in buying from multiple sellers of certain amount of bandwidth from each, depending on price and meeting requirements and budget constraints. Stability of the model is analyzed and performance evaluation shows that it benefits sellers and buyers in terms of profit and throughput, respectively. © 2015 Elsevier B.V. All rights reserved.