title: Supercapacitor assisted LED (SCALED) converter technique for solar powered DC-microgrids

authors: Udathenne Gedara, Dilini Udeshika Kumari Jayananda

abstract: Designing electronic products and systems with high energy efficiency is a major challenge for electronic power circuit designers. Almost all residential and industrial buildings are presently AC powered. However, they contain electronic equipment that is internally dependent on a bulk DC power rail with multiple DC-DC converters or DC-AC converters to supply motors controlled by variable speed drives. The overall efficiency of an electronic device with multiple voltage converters is determined by the product of the efficiencies of the individual conversion stages. Thus, overall efficiency drops drastically with the number of converter stages. However, with renewable energy sources such as photovoltaic solar cells generating DC electricity, we can eliminate the first AC-DC converter and reduce the number of converter stages, to achieve a signi ficant rise in end-to-end efficiency. This is the motivation for the DC-microgrid concept. DC-microgrids are local energy networks consisting of renewable energy sources and storage systems.
Although power generation using solar energy is economical, designers have to cope with frequent fluctuations in irradiance and temperature and the non-availability of solar energy at night. Accordingly, there is a need for energy storage for reliable operation. The most common energy storage device used in solar power-based systems is the rechargeable battery pack, typically based on lead-acid and lithium-ion chemistries. However, all rechargeable batteries have limited charge-discharge life cycles as well as calendar lives, and are environmentally unfriendly. With the continuous developments of supercapacitor materials and manufacturing techniques over the last decade, it is now possible to adopt supercapacitors as short-term energy storage devices in solar powered DC-microgrids to replace electrochemical battery packs. When supercapacitors are used in solar power-based DC-microgrid environments, there is the possibility of directly operating \white goods" (such as washing machines, refrigerators, dishwashers and air conditioners) and lighting. However, if a supercapacitor bank is used as the sole energy storage, existing maximum power point tracking schemes are no longer appropriate. This is because the storage bank acts as a near-ideal capacitor, so its impedance depends on its state of charge, unlike a rechargeable battery pack with internal resistance.
The supercapacitor assisted LED lighting (SCALED) converter is a new circuit topology that can be applied to solar powered DC-microgrids. This topology has been developed specially for low voltage LED lighting systems where a supercapacitor bank is used as an efficient energy storage device instead of a battery bank. The SCALED converter is another extension of the supercapacitor assisted loss management concept developed by the Power Electronics research team at the University of Waikato. This thesis presents details of this SCALED conversion system, developed for the Ports of Auckland DC-microgrid lighting systems, including theory and experimental efficiency measurements.

text: Supercapacitor assisted LED (SCALED) converter technique for solar powered DC-microgrids Designing electronic products and systems with high energy efficiency is a major challenge for electronic power circuit designers. Almost all residential and industrial buildings are presently AC powered. However, they contain electronic equipment that is internally dependent on a bulk DC power rail with multiple DC-DC converters or DC-AC converters to supply motors controlled by variable speed drives. The overall efficiency of an electronic device with multiple voltage converters is determined by the product of the efficiencies of the individual conversion stages. Thus, overall efficiency drops drastically with the number of converter stages. However, with renewable energy sources such as photovoltaic solar cells generating DC electricity, we can eliminate the first AC-DC converter and reduce the number of converter stages, to achieve a signi ficant rise in end-to-end efficiency. This is the motivation for the DC-microgrid concept. DC-microgrids are local energy networks consisting of renewable energy sources and storage systems.
Although power generation using solar energy is economical, designers have to cope with frequent fluctuations in irradiance and temperature and the non-availability of solar energy at night. Accordingly, there is a need for energy storage for reliable operation. The most common energy storage device used in solar power-based systems is the rechargeable battery pack, typically based on lead-acid and lithium-ion chemistries. However, all rechargeable batteries have limited charge-discharge life cycles as well as calendar lives, and are environmentally unfriendly. With the continuous developments of supercapacitor materials and manufacturing techniques over the last decade, it is now possible to adopt supercapacitors as short-term energy storage devices in solar powered DC-microgrids to replace electrochemical battery packs. When supercapacitors are used in solar power-based DC-microgrid environments, there is the possibility of directly operating \white goods" (such as washing machines, refrigerators, dishwashers and air conditioners) and lighting. However, if a supercapacitor bank is used as the sole energy storage, existing maximum power point tracking schemes are no longer appropriate. This is because the storage bank acts as a near-ideal capacitor, so its impedance depends on its state of charge, unlike a rechargeable battery pack with internal resistance.
The supercapacitor assisted LED lighting (SCALED) converter is a new circuit topology that can be applied to solar powered DC-microgrids. This topology has been developed specially for low voltage LED lighting systems where a supercapacitor bank is used as an efficient energy storage device instead of a battery bank. The SCALED converter is another extension of the supercapacitor assisted loss management concept developed by the Power Electronics research team at the University of Waikato. This thesis presents details of this SCALED conversion system, developed for the Ports of Auckland DC-microgrid lighting systems, including theory and experimental efficiency measurements.

year: 2020

title: Genre, academic writing and e-learning: An integrated tertiary level Taiwan-based study

authors: Lin, Hsiu-Chen (Antonia)

subjects: genre

abstract: The research reported here has two main focus points: online learning and the teaching of academic writing to learners of English as an additional language. At its core is a study involving an intensive genre-centered writing course conducted in a tertiary educational institution in Taiwan and delivered in three modes - face-to-face, fully online and blended. That study, preceded by a pilot study conducted in New Zealand, involved a writing course that focused on cognitive genres (e.g. argument) that have been identified as being fundamental to academic writing. It included model texts (constructed in segments with accompanying discussion of their language and structure) and writing exercises. Analysis of post-course questionnaires and focus group discussions revealed a high level of satisfaction with the course. Analysis of pre-test and post-test writing tasks in terms of a wide range of criteria provided evidence of improvement in the writing of course participants in a range of areas. Although those involved in blended and face-to-face modes were most positive about the advantages of the course, it was not necessarily always the case that they outperformed online group members in terms of improvement in writing. 

Also included are two questionnaire-based surveys of samples of teachers of English in tertiary level educational institutions in Taiwan. The first investigated attitudes and practices in relation to the integration of instructional technology into teaching. Although the vast majority of survey participants believed that it was important to incorporate instructional technology into their teaching, this was not necessarily reflected in their more specific beliefs and practices. Very few reported having spent more than a few hours attending instructional technology-related workshops, more than half indicated that very little or none of the interaction in their language classes was computer-mediated, only approximately one third reported having used a learning platform in the six weeks prior to the survey, and over one third reported that they had never used a learning platform. The second questionnaire-based survey investigated attitudes and practices in relation to the teaching and assessment of writing. Although survey participants were familiar with process-centered approaches to the teaching of writing, they appeared to be much less familiar with genre-centered approaches. Using model texts as a way of introducing, demonstrating and explaining language in use seemed to be the exception rather than the rule. Additionally, although they reported spending a considerable amount of time grading and commenting on their students' writing, most of them indicated that they did not design grading criteria that related specifically to course content, and many of the sample comments on student writing that they provided were of a type that is unlikely to help students to improve their writing. 

Overall, the study provides evidence that a genre-centered academic writing course can be associated with a high level of student satisfaction and can lead to demonstrable improvement in student writing. However, it also demonstrates that teachers of English at tertiary level in Taiwan are generally unfamiliar with this sort of approach and that many of them are not yet ready to provide their students with options in terms of delivery modes.

text: Genre, academic writing and e-learning: An integrated tertiary level Taiwan-based study The research reported here has two main focus points: online learning and the teaching of academic writing to learners of English as an additional language. At its core is a study involving an intensive genre-centered writing course conducted in a tertiary educational institution in Taiwan and delivered in three modes - face-to-face, fully online and blended. That study, preceded by a pilot study conducted in New Zealand, involved a writing course that focused on cognitive genres (e.g. argument) that have been identified as being fundamental to academic writing. It included model texts (constructed in segments with accompanying discussion of their language and structure) and writing exercises. Analysis of post-course questionnaires and focus group discussions revealed a high level of satisfaction with the course. Analysis of pre-test and post-test writing tasks in terms of a wide range of criteria provided evidence of improvement in the writing of course participants in a range of areas. Although those involved in blended and face-to-face modes were most positive about the advantages of the course, it was not necessarily always the case that they outperformed online group members in terms of improvement in writing. 

Also included are two questionnaire-based surveys of samples of teachers of English in tertiary level educational institutions in Taiwan. The first investigated attitudes and practices in relation to the integration of instructional technology into teaching. Although the vast majority of survey participants believed that it was important to incorporate instructional technology into their teaching, this was not necessarily reflected in their more specific beliefs and practices. Very few reported having spent more than a few hours attending instructional technology-related workshops, more than half indicated that very little or none of the interaction in their language classes was computer-mediated, only approximately one third reported having used a learning platform in the six weeks prior to the survey, and over one third reported that they had never used a learning platform. The second questionnaire-based survey investigated attitudes and practices in relation to the teaching and assessment of writing. Although survey participants were familiar with process-centered approaches to the teaching of writing, they appeared to be much less familiar with genre-centered approaches. Using model texts as a way of introducing, demonstrating and explaining language in use seemed to be the exception rather than the rule. Additionally, although they reported spending a considerable amount of time grading and commenting on their students' writing, most of them indicated that they did not design grading criteria that related specifically to course content, and many of the sample comments on student writing that they provided were of a type that is unlikely to help students to improve their writing. 

Overall, the study provides evidence that a genre-centered academic writing course can be associated with a high level of student satisfaction and can lead to demonstrable improvement in student writing. However, it also demonstrates that teachers of English at tertiary level in Taiwan are generally unfamiliar with this sort of approach and that many of them are not yet ready to provide their students with options in terms of delivery modes.

year: 2010

title: Characteristics and outcomes of patients with small cell lung cancer - findings from a New Zealand SACT database

authors: Lawrenson, Ross

abstract: Background Small Cell Lung Cancer (SCLC) SCLC generally presents late and is treated with systemic anti-cancer treatment (SACT). Māori are over represented in Lung Cancer statistics but disparities between Māori and non-Māori in patterns of care and survival from SCLC have not been previously reported. 
Methods We used the custom-built SACT database collected by the Oncology Department at Waikato Hospital NZ, which recorded comprehensive lung cancer patient factors and SACT regimens from 2000 to 2021. We reported summary statistics to review the treatment by ethnicity, explored Kaplan Meier all-cause survival of patients, and estimated the unadjusted and adjusted odds ratios of surviving 12 months. 
Results 742 patients with SCLC were included in this study, with 43% identified as Māori. Approximately 75% of patients received SACT, and there was no difference in the uptake of SACT between Māori and non-Māori. The median survival for SCLC was 8.5 months. After adjustment, patients treated with carboplatin plus etoposide (with/without durvalumab) or cisplatin plus etoposide were 1.5 times or 4.9 times respectively more likely to survive 12 months than those without a SACT regimen.
Conclusion There was no significant evidence of disparities in patterns of care and outcomes between Māori and non-Māori with SCLC. Carboplatin/cisplatin in combination with etoposide remained the primary first line SACT regimen for patients with SCLC in this New Zealand cancer treatment centre.

text: Characteristics and outcomes of patients with small cell lung cancer - findings from a New Zealand SACT database Background Small Cell Lung Cancer (SCLC) SCLC generally presents late and is treated with systemic anti-cancer treatment (SACT). Māori are over represented in Lung Cancer statistics but disparities between Māori and non-Māori in patterns of care and survival from SCLC have not been previously reported. 
Methods We used the custom-built SACT database collected by the Oncology Department at Waikato Hospital NZ, which recorded comprehensive lung cancer patient factors and SACT regimens from 2000 to 2021. We reported summary statistics to review the treatment by ethnicity, explored Kaplan Meier all-cause survival of patients, and estimated the unadjusted and adjusted odds ratios of surviving 12 months. 
Results 742 patients with SCLC were included in this study, with 43% identified as Māori. Approximately 75% of patients received SACT, and there was no difference in the uptake of SACT between Māori and non-Māori. The median survival for SCLC was 8.5 months. After adjustment, patients treated with carboplatin plus etoposide (with/without durvalumab) or cisplatin plus etoposide were 1.5 times or 4.9 times respectively more likely to survive 12 months than those without a SACT regimen.
Conclusion There was no significant evidence of disparities in patterns of care and outcomes between Māori and non-Māori with SCLC. Carboplatin/cisplatin in combination with etoposide remained the primary first line SACT regimen for patients with SCLC in this New Zealand cancer treatment centre.

year: 2023-02-10