title: Input and output considerations in estimating rates of chemical denudation

authors: Goudie, Andrew

abstract: Estimation of rates of solutional denudation in river basins necessitates some consideration of salt inputs as well as consideration of salt outputs. Recent work in nutrient cycling has stressed the complexity and importance of the input factor, particularly when throughfall chemistry is taken into account. Frequently the differences between rates of input and output of salt in a river basin are small, suggesting that many published rates of solutional denudation, which consider outputs alone, or inputs only in part, are excessive. The input of salts, which may take place in rain, snow, fog and throughfall are most important in coastal areas. Analysis of data, for both the semi-arid United States and the Cotswold Hills in England, illustrate the need for long-term sampling, and for a detailed spatial network of sampling points.

text: Input and output considerations in estimating rates of chemical denudation Estimation of rates of solutional denudation in river basins necessitates some consideration of salt inputs as well as consideration of salt outputs. Recent work in nutrient cycling has stressed the complexity and importance of the input factor, particularly when throughfall chemistry is taken into account. Frequently the differences between rates of input and output of salt in a river basin are small, suggesting that many published rates of solutional denudation, which consider outputs alone, or inputs only in part, are excessive. The input of salts, which may take place in rain, snow, fog and throughfall are most important in coastal areas. Analysis of data, for both the semi-arid United States and the Cotswold Hills in England, illustrate the need for long-term sampling, and for a detailed spatial network of sampling points.

year: 1970

title: Open-source tool for heat exchanger network synthesis

authors: Hall, Keegan

abstract: The synthesis of heat exchanger networks (HEN) is not a trivial task due to the mixed integer and non-linear nature of the optimisation problem, yet it can provide significant cost and energy use savings to an industrial processing site. Many HEN synthesis models are developed using propriety solvers, which make it difficult for industrial companies to realise the potential of optimisation. This paper introduces a new open-source tool for HEN synthesis built in Python using the GEKKO library, which interfaces with the solver APOPT. The tool features three different synthesis methods, two of which utilise a two-step method where step one aims to initialise or narrow the search space prior to global optimisation in the second synthesis step. A unique feature of this work compared to previous HEN synthesis studies is the application of a true driving force constraint, dQ/dA, (instead of the conventional, but at times crude, minimum approach temperature, ∆Tmin) to provide feasible initial variable values to the second step. To demonstrate the current progress in developing the open-source tool, network solutions obtained by the tool were purposefully compared with the best reported solutions for three common case studies in HEN synthesis literature. For a small problem, the tool achieved a solution within 0.02 % of the best literature solution and attained a solution for the two larger problems within 4 % and 21% of the best literature solution. Before the tool can be made publicly available, further work is needed to implement a non-isothermal mixing model across stream splits, which is expected to yield a more optimal HEN.

text: Open-source tool for heat exchanger network synthesis The synthesis of heat exchanger networks (HEN) is not a trivial task due to the mixed integer and non-linear nature of the optimisation problem, yet it can provide significant cost and energy use savings to an industrial processing site. Many HEN synthesis models are developed using propriety solvers, which make it difficult for industrial companies to realise the potential of optimisation. This paper introduces a new open-source tool for HEN synthesis built in Python using the GEKKO library, which interfaces with the solver APOPT. The tool features three different synthesis methods, two of which utilise a two-step method where step one aims to initialise or narrow the search space prior to global optimisation in the second synthesis step. A unique feature of this work compared to previous HEN synthesis studies is the application of a true driving force constraint, dQ/dA, (instead of the conventional, but at times crude, minimum approach temperature, ∆Tmin) to provide feasible initial variable values to the second step. To demonstrate the current progress in developing the open-source tool, network solutions obtained by the tool were purposefully compared with the best reported solutions for three common case studies in HEN synthesis literature. For a small problem, the tool achieved a solution within 0.02 % of the best literature solution and attained a solution for the two larger problems within 4 % and 21% of the best literature solution. Before the tool can be made publicly available, further work is needed to implement a non-isothermal mixing model across stream splits, which is expected to yield a more optimal HEN.

year: 2022-09-05

title: Māori data governance model

authors: Kukutai, Tahu

abstract: This report describes the Māori Data Governance Model that has been designed by Māori data experts for use across the Aotearoa New Zealand public service. Māori data is a taonga that requires culturally grounded models of protection and care. The Model provides guidance for the system-wide governance of Māori data, consistent with the Government’s responsibilities under te Tiriti o Waitangi. The Model is intended to assist all agencies to undertake Māori data governance in a way that is values-led, centred on Māori needs and priorities, and informed by research. This is important because existing government data processes and practices are failing to meet Māori informational needs.

The Vision, Tuia te korowai o Hine-Raraunga – Data for self-determination, enables iwi, hapū and Māori organisations, businesses and communities to pursue their own goals for cultural, social, economic and environmental wellbeing. Eight Data Pou or pillars define critical areas of data governance and specify the actions that should be undertaken to realise six desired outcomes. The Model does not cover every element of data governance; instead, it focuses on key priorities and actions, against which agencies can assess their level of data maturity. The Model explicitly recognises the need for changes to system leadership, policies and legal settings so that Māori can exercise authority over Māori data to reduce unethical data use and strengthen outcomes for individuals, whānau and communities. The report also identifies the need for strategic investment in a Mana Motuhake data system that sits outside of the public sector to ensure iwi and hapū sovereignty over iwi and hapū data.

text: Māori data governance model This report describes the Māori Data Governance Model that has been designed by Māori data experts for use across the Aotearoa New Zealand public service. Māori data is a taonga that requires culturally grounded models of protection and care. The Model provides guidance for the system-wide governance of Māori data, consistent with the Government’s responsibilities under te Tiriti o Waitangi. The Model is intended to assist all agencies to undertake Māori data governance in a way that is values-led, centred on Māori needs and priorities, and informed by research. This is important because existing government data processes and practices are failing to meet Māori informational needs.

The Vision, Tuia te korowai o Hine-Raraunga – Data for self-determination, enables iwi, hapū and Māori organisations, businesses and communities to pursue their own goals for cultural, social, economic and environmental wellbeing. Eight Data Pou or pillars define critical areas of data governance and specify the actions that should be undertaken to realise six desired outcomes. The Model does not cover every element of data governance; instead, it focuses on key priorities and actions, against which agencies can assess their level of data maturity. The Model explicitly recognises the need for changes to system leadership, policies and legal settings so that Māori can exercise authority over Māori data to reduce unethical data use and strengthen outcomes for individuals, whānau and communities. The report also identifies the need for strategic investment in a Mana Motuhake data system that sits outside of the public sector to ensure iwi and hapū sovereignty over iwi and hapū data.

year: 2023