title: Eliciting informative priors by modeling expert decision making

authors: Falconer, Julia Ruth

abstract: There are significant limitations to current methods for eliciting the prior beliefs of experts. To combat some of these limitations, this paper proposes an alternative approach that infers an expert’s prior beliefs about an uncertain event, A, from the expert’s past decisions. We show that an analyst can use past information on an expert’s decision-making task, contingent on an expert’s prior of A, to model the decision-making process and infer an approximation of the prior for A. This concept is illustrated by an application to recidivism. We conclude this work by highlighting important directions for future research. Funding: J. R. Falconer’s research is funded through the University of Waikato Doctoral Scholarship.

text: Eliciting informative priors by modeling expert decision making There are significant limitations to current methods for eliciting the prior beliefs of experts. To combat some of these limitations, this paper proposes an alternative approach that infers an expert’s prior beliefs about an uncertain event, A, from the expert’s past decisions. We show that an analyst can use past information on an expert’s decision-making task, contingent on an expert’s prior of A, to model the decision-making process and infer an approximation of the prior for A. This concept is illustrated by an application to recidivism. We conclude this work by highlighting important directions for future research. Funding: J. R. Falconer’s research is funded through the University of Waikato Doctoral Scholarship.

year: 2023

title: New high temperature transcritical CO2 heat pump concept for spray drying

authors: Kong, Lana

subjects: high temperature heat pump

abstract: The need to decarbonise the industrial sector requires new innovations in high temperature heating. The development of an industrial high temperature heat pump presents not only great emissions reduction potential but also cost saving potential for industrial process heat users. Compared to boilers with efficiencies ranging from 70 to 99%, heat pumps have the ability to leverage renewable electricity to supply heating as a standalone technology (air-source heat pumps), with one unit if electricity being able to supply multiple units of heat (Coefficient of Performance > 1) or integrate with existing boilers to reduce steam demand (air-source or waste heat recovery).
This thesis investigates a novel high temperature transcritical CO2 heat pump concept using a case study in milk powder spray drying. A series of cycle architectures were modelled that incorporated internal heat exchangers and cascade arrangements to assess their effect on thermodynamic performance for not only large temperature lifts (>150 °C) but also large temperature glides (>150 °C). A transcritical-transcritical cascade configuration was found to achieve a sink temperature of 200 °C with a COP of 2.22 at moderate discharge pressures (150 bar) compared to what is currently available in the literature (>200 bar). Expansion work recovery, using ejectors and expanders, was further explored to reduce exergy losses, achieving incremental COP gains up to 2.35. However, it was determined that, at this stage, the marginal increases in COP did not overcome the challenges in complexity of integrating an expander or ejector within the system.

A comparison of integration options was undertaken that compared the high temperature heat pump integration with fuel switching to electrode or biomass boilers. Hybrid configurations of heat pump and boilers were also assessed at varying utility prices to determine whether an optimum sink temperature existed to minimise the operational cost. With this, a multi-temperature heat pump configuration was found to improve the COP of the heat pump to 2.55 for air heating to 200 °C, which emphasises the importance of temperature profile matching in heat pump design. Operating costs depended on the electricity-to-biomass price ratio and grid emissions intensity. In all cases, electrode boiler conversions had the highest operational cost. Price ratios below 2.75 were favourable for full electrification using a heat pump, while price ratios above 3.67 favoured a full biomass conversion. Between these two price ratios, the optimal hybrid configuration was to supply the air heating up to the temperature level for the fluidised bed (102 °C) using a heat pump and supply the remainder of the heating using a biomass boiler. In comparison to coal, the proposed solutions achieved emissions savings between 55 and 94 %.

The wider potential for the high temperature heat pump concept was then estimated, revealing a broader potential for CO2 high temperature heat pumps to supply hundreds of petajoules per year of low-carbon heat across a diverse range of industrial sectors. Due to being able to produce both large temperature glides and large temperature lifts, the CO2 high temperature heat pump was particularly suited for a range of drying processes (further than milk powder spray drying). Potential source and sink streams for the heat pump were identified for each application to estimate possible COPs, which ranged between 2.0 and 3.05 for sink outlet temperatures ranging from 110 to 280 °C. Emissions reduction was shown to be viable for nearly all regions when displacing coal, but requires cleaner electricity grids or higher COPs when displacing natural gas.

This thesis contributes an in depth thermodynamic analysis of both a novel high temperature heat pump cycle architecture and a novel application of high temperature heat pumps into the milk powder spray drying process. Additionally, this thesis contributes a cross-sectoral analysis for implementation, collating potential source and sink streams across a variety of applications.

text: New high temperature transcritical CO2 heat pump concept for spray drying The need to decarbonise the industrial sector requires new innovations in high temperature heating. The development of an industrial high temperature heat pump presents not only great emissions reduction potential but also cost saving potential for industrial process heat users. Compared to boilers with efficiencies ranging from 70 to 99%, heat pumps have the ability to leverage renewable electricity to supply heating as a standalone technology (air-source heat pumps), with one unit if electricity being able to supply multiple units of heat (Coefficient of Performance > 1) or integrate with existing boilers to reduce steam demand (air-source or waste heat recovery).
This thesis investigates a novel high temperature transcritical CO2 heat pump concept using a case study in milk powder spray drying. A series of cycle architectures were modelled that incorporated internal heat exchangers and cascade arrangements to assess their effect on thermodynamic performance for not only large temperature lifts (>150 °C) but also large temperature glides (>150 °C). A transcritical-transcritical cascade configuration was found to achieve a sink temperature of 200 °C with a COP of 2.22 at moderate discharge pressures (150 bar) compared to what is currently available in the literature (>200 bar). Expansion work recovery, using ejectors and expanders, was further explored to reduce exergy losses, achieving incremental COP gains up to 2.35. However, it was determined that, at this stage, the marginal increases in COP did not overcome the challenges in complexity of integrating an expander or ejector within the system.

A comparison of integration options was undertaken that compared the high temperature heat pump integration with fuel switching to electrode or biomass boilers. Hybrid configurations of heat pump and boilers were also assessed at varying utility prices to determine whether an optimum sink temperature existed to minimise the operational cost. With this, a multi-temperature heat pump configuration was found to improve the COP of the heat pump to 2.55 for air heating to 200 °C, which emphasises the importance of temperature profile matching in heat pump design. Operating costs depended on the electricity-to-biomass price ratio and grid emissions intensity. In all cases, electrode boiler conversions had the highest operational cost. Price ratios below 2.75 were favourable for full electrification using a heat pump, while price ratios above 3.67 favoured a full biomass conversion. Between these two price ratios, the optimal hybrid configuration was to supply the air heating up to the temperature level for the fluidised bed (102 °C) using a heat pump and supply the remainder of the heating using a biomass boiler. In comparison to coal, the proposed solutions achieved emissions savings between 55 and 94 %.

The wider potential for the high temperature heat pump concept was then estimated, revealing a broader potential for CO2 high temperature heat pumps to supply hundreds of petajoules per year of low-carbon heat across a diverse range of industrial sectors. Due to being able to produce both large temperature glides and large temperature lifts, the CO2 high temperature heat pump was particularly suited for a range of drying processes (further than milk powder spray drying). Potential source and sink streams for the heat pump were identified for each application to estimate possible COPs, which ranged between 2.0 and 3.05 for sink outlet temperatures ranging from 110 to 280 °C. Emissions reduction was shown to be viable for nearly all regions when displacing coal, but requires cleaner electricity grids or higher COPs when displacing natural gas.

This thesis contributes an in depth thermodynamic analysis of both a novel high temperature heat pump cycle architecture and a novel application of high temperature heat pumps into the milk powder spray drying process. Additionally, this thesis contributes a cross-sectoral analysis for implementation, collating potential source and sink streams across a variety of applications.

year: 2026

title: Hā Ora: secondary care barriers and enablers to early diagnosis of lung cancer for Māori communities.

authors: Kidd, Jacquie

subjects: Barriers

abstract: BACKGROUND: Lung Cancer is the leading cause of cancer deaths in Aotearoa New Zealand. Māori communities in particular have higher incidence and mortality rates from Lung Cancer. Diagnosis of lung cancer at an early stage can allow for curative treatment. This project aimed to document the barriers to early diagnosis and treatment of lung cancer in secondary care for Māori communities. 
METHODS: This project used a kaupapa Māori approach. Nine community hui (focus groups) and nine primary healthcare provider hui were carried out in five rural localities in the Midland region. Community hui included cancer patients, whānau (families), and other community members. Healthcare provider hui comprised staff members at the local primary healthcare centre, including General Practitioners and nurses. Hui data were thematically analysed. 
RESULTS: Barriers and enablers to early diagnosis of lung cancer were categorised into two broad themes: Specialist services and treatment, and whānau journey. The barriers and enablers that participants experienced in specialist services and treatment related to access to care, engagement with specialists, communication with specialist services and cultural values and respect, whereas barriers and enablers relating to the whānau journey focused on agency and the impact on whānau. 
CONCLUSIONS: The study highlighted the need to improve communication within and across healthcare services, the importance of understanding the cultural needs of patients and whānau and a health system strategy that meets these needs. Findings also demonstrated the resilience of Māori and the active efforts of whānau as carers to foster health literacy in future generations.

text: Hā Ora: secondary care barriers and enablers to early diagnosis of lung cancer for Māori communities. BACKGROUND: Lung Cancer is the leading cause of cancer deaths in Aotearoa New Zealand. Māori communities in particular have higher incidence and mortality rates from Lung Cancer. Diagnosis of lung cancer at an early stage can allow for curative treatment. This project aimed to document the barriers to early diagnosis and treatment of lung cancer in secondary care for Māori communities. 
METHODS: This project used a kaupapa Māori approach. Nine community hui (focus groups) and nine primary healthcare provider hui were carried out in five rural localities in the Midland region. Community hui included cancer patients, whānau (families), and other community members. Healthcare provider hui comprised staff members at the local primary healthcare centre, including General Practitioners and nurses. Hui data were thematically analysed. 
RESULTS: Barriers and enablers to early diagnosis of lung cancer were categorised into two broad themes: Specialist services and treatment, and whānau journey. The barriers and enablers that participants experienced in specialist services and treatment related to access to care, engagement with specialists, communication with specialist services and cultural values and respect, whereas barriers and enablers relating to the whānau journey focused on agency and the impact on whānau. 
CONCLUSIONS: The study highlighted the need to improve communication within and across healthcare services, the importance of understanding the cultural needs of patients and whānau and a health system strategy that meets these needs. Findings also demonstrated the resilience of Māori and the active efforts of whānau as carers to foster health literacy in future generations.

year: 2021