title: Charge capacity characteristics of a Lithium Nickel-Cobalt-Aluminum Oxide battery show fractional-derivative behavior

authors: Wilson, Marcus T.

subjects: cs.SY

abstract: Batteries experience capacity offset where available charge depends on the
rate at which this charge is drawn. In this work we analyze the capacity offset
of a 4.8 A h lithium nickel-cobalt-aluminium oxide battery using an equivalent
circuit model of a fractional capacitor in series with a resistor. In this
case, the available charge, in theory, becomes infinite in the limit of
infinitesimal rate. We show that the fractional properties of the capacitor can
be extracted from the charge against rate plot. We then use a network of RC
elements to represent the fractional capacitor in order to simulate the data
with Matlab. We find that the fractional exponent alpha obtained in this way,
0.971, agrees with that obtained in a more traditional manner from an impedance
versus frequency plot, although the fractional capacity does not. Such an
approach demonstrates the importance of a fractional description for capacity
offset even when an element is nearly a pure capacitor and is valuable for
predictions of state-of-charge when low currents are drawn.

text: Charge capacity characteristics of a Lithium Nickel-Cobalt-Aluminum Oxide battery show fractional-derivative behavior Batteries experience capacity offset where available charge depends on the
rate at which this charge is drawn. In this work we analyze the capacity offset
of a 4.8 A h lithium nickel-cobalt-aluminium oxide battery using an equivalent
circuit model of a fractional capacitor in series with a resistor. In this
case, the available charge, in theory, becomes infinite in the limit of
infinitesimal rate. We show that the fractional properties of the capacitor can
be extracted from the charge against rate plot. We then use a network of RC
elements to represent the fractional capacitor in order to simulate the data
with Matlab. We find that the fractional exponent alpha obtained in this way,
0.971, agrees with that obtained in a more traditional manner from an impedance
versus frequency plot, although the fractional capacity does not. Such an
approach demonstrates the importance of a fractional description for capacity
offset even when an element is nearly a pure capacitor and is valuable for
predictions of state-of-charge when low currents are drawn.

year: 2021

title: Prediction of the mechanical properties of isotropic pure metal-based and two-phase alloy-based porous materials using modified analytical models

authors: Bolzoni, Leandro

abstract: This work investigates the applicability and accuracy of the five fundamental analytical models commonly used to estimate the thermophysical properties of porous materials for the prediction of the mechanical behaviour, both compressive and tensile, of isotropic pure metal-based and two-phase alloy-based porous materials. In literature, the prediction of the mechanical behaviour of these advanced engineering materials requires the development of semi-empirical models, which are material-specific and, thus, require empirical constants. The significance of the current investigation is the possibility to optimise the mechanical behaviour of porous metallic materials through the rapid and accurate prediction of their mechano-physical behaviour using non-empirical physically-based prediction models. The work is complemented with the derivation of new combined models with increased accuracy prediction of up to approx. 90% with respect to fundamental models. Although developed for porous materials, the derived combined models could be applied for the accurate and rapid prediction of the thermophysical and mechanical properties of multi-phase materials with unknown microstructure such as two-ductile-phase alloys, nanocomposites, hetero- and harmonic-structured materials, and immiscible alloys.

text: Prediction of the mechanical properties of isotropic pure metal-based and two-phase alloy-based porous materials using modified analytical models This work investigates the applicability and accuracy of the five fundamental analytical models commonly used to estimate the thermophysical properties of porous materials for the prediction of the mechanical behaviour, both compressive and tensile, of isotropic pure metal-based and two-phase alloy-based porous materials. In literature, the prediction of the mechanical behaviour of these advanced engineering materials requires the development of semi-empirical models, which are material-specific and, thus, require empirical constants. The significance of the current investigation is the possibility to optimise the mechanical behaviour of porous metallic materials through the rapid and accurate prediction of their mechano-physical behaviour using non-empirical physically-based prediction models. The work is complemented with the derivation of new combined models with increased accuracy prediction of up to approx. 90% with respect to fundamental models. Although developed for porous materials, the derived combined models could be applied for the accurate and rapid prediction of the thermophysical and mechanical properties of multi-phase materials with unknown microstructure such as two-ductile-phase alloys, nanocomposites, hetero- and harmonic-structured materials, and immiscible alloys.

year: 2021

title: Kua Huri Taku Tira: The Rereahu Journey Towards Autonomy

authors: Crown, Jenny

subjects: autonomy

abstract: The establishment of the Native Land Court in Aotearoa New Zealand by the settler government caused much upheaval for tangata whenua. Traditional land tenure was interrupted by the colonised view of land ownership. Impetus to establish individual ownership of land was placed upon iwi and hapū Māori. This necessitated the iwi and hapū of the Rohe Pōtae to define their own individual boundaries within the autonomous region.

Over one hundred years later, the New Zealand government were under pressure from the Māori community. Iwi and hapū were vociferous in their requirements. The returning of land and natural resources to Māori was of paramount importance. The implementation of the Māori Trust Board Act enabled iwi and hapū to establish governance entities which permitted access to government funding. These entities also provided a vehicle through which iwi could pursue cultural redress from the Crown. This was the only way forward – the way dictated by the Crown.

Devolution was to become a reality and a sign of the decolonisation process at play. Such would allow Māori to re-establish autonomy which had been lost over a century prior. Destructive notions such as marginalisation, disenfranchisement and displacement would be reversed and Māori would regain control over their own cultural practices, cultural resources and future. Under the Fourth Labour Government of New Zealand this became a reality for some iwi and hapū.

This thesis investigates the attempts made by the Rereahu iwi in securing such recognition. Interrogation into the many ways in which Rereahu has attempted to navigate the multiple political landscapes which still exist and continue to control iwi and hapū have been discussed. The study develops a theoretical framework of Māori wide concepts as applied through a Rereahu-centric lens. Thus, allowing for a balanced approach to the collection, collation and analysis of all evidence utilised in this thesis.

Key findings bring to light the effects colonisation has had and continues to have on Rereahu autonomy. The ways in which Rereahu has been misrepresented, and how Rereahu has responded to threats of colonisation in the 21st century are apparent. This thesis contributes new knowledge to the realm of academia through the experiences of the iwi Rereahu; and offers indigenous discourse regarding resilience and resistance.

The ongoing effects of colonisation being felt by the Rereahu iwi in this contemporary landscape are defined. It is an example of how the oppressed can easily become the oppressor. This thesis goes some way to highlighting the destructive nature of the Waitangi Tribunal process in regards to Rereahu. The knowledge presented in this thesis could be utilised by the Office of Treaty Settlements, education and health establishments, policy makers and the iwi of Rereahu in addressing and combating the negative effects created by the cycle of colonisation.

text: Kua Huri Taku Tira: The Rereahu Journey Towards Autonomy The establishment of the Native Land Court in Aotearoa New Zealand by the settler government caused much upheaval for tangata whenua. Traditional land tenure was interrupted by the colonised view of land ownership. Impetus to establish individual ownership of land was placed upon iwi and hapū Māori. This necessitated the iwi and hapū of the Rohe Pōtae to define their own individual boundaries within the autonomous region.

Over one hundred years later, the New Zealand government were under pressure from the Māori community. Iwi and hapū were vociferous in their requirements. The returning of land and natural resources to Māori was of paramount importance. The implementation of the Māori Trust Board Act enabled iwi and hapū to establish governance entities which permitted access to government funding. These entities also provided a vehicle through which iwi could pursue cultural redress from the Crown. This was the only way forward – the way dictated by the Crown.

Devolution was to become a reality and a sign of the decolonisation process at play. Such would allow Māori to re-establish autonomy which had been lost over a century prior. Destructive notions such as marginalisation, disenfranchisement and displacement would be reversed and Māori would regain control over their own cultural practices, cultural resources and future. Under the Fourth Labour Government of New Zealand this became a reality for some iwi and hapū.

This thesis investigates the attempts made by the Rereahu iwi in securing such recognition. Interrogation into the many ways in which Rereahu has attempted to navigate the multiple political landscapes which still exist and continue to control iwi and hapū have been discussed. The study develops a theoretical framework of Māori wide concepts as applied through a Rereahu-centric lens. Thus, allowing for a balanced approach to the collection, collation and analysis of all evidence utilised in this thesis.

Key findings bring to light the effects colonisation has had and continues to have on Rereahu autonomy. The ways in which Rereahu has been misrepresented, and how Rereahu has responded to threats of colonisation in the 21st century are apparent. This thesis contributes new knowledge to the realm of academia through the experiences of the iwi Rereahu; and offers indigenous discourse regarding resilience and resistance.

The ongoing effects of colonisation being felt by the Rereahu iwi in this contemporary landscape are defined. It is an example of how the oppressed can easily become the oppressor. This thesis goes some way to highlighting the destructive nature of the Waitangi Tribunal process in regards to Rereahu. The knowledge presented in this thesis could be utilised by the Office of Treaty Settlements, education and health establishments, policy makers and the iwi of Rereahu in addressing and combating the negative effects created by the cycle of colonisation.

year: 2019