title: Characterisation and prediction of state of health of rechargeable batteries

authors: Dunn, Christopher

subjects: electrochemical impedance spectroscopy (EIS)

abstract: Electrochemical impedance spectroscopy (EIS) is used extensively in battery research, but usually at frequencies that do not reflect real-world usage patterns. This has resulted in equivalent circuit models (ECMs) that are over-complicated, and suboptimal battery management systems. It is logical to measure batteries at frequencies reflecting their daily or weekly charge-discharge cycles, i.e., of the order of microhertz. This is generally not done, however, because of difficulties that include extreme measurement durations and the need for care to avoid issues such as charge distribution problems, charge drift, and the risk of overcharging or flattening the battery. This research demonstrates the feasibility of extra-low frequency (ELF) EIS measurement using standard, non-specialised measurement equipment, and the optimisation of frequency domain data through the superimposition of small-signal measurement tones on larger square wave currents.

Study of charge movement rates in the frequency domain and voltage responses in the time domain in batteries indicates connections between voltage sweep rate in cyclic voltammetry (CV) and current magnitude in incremental capacity analysis (ICA). The key factor determining what the investigator sees, e.g., reversibility  of electrode processes or evidence of individual electrochemical reactions, is rate of movement of charge. Thus, controlled current can be used to obtain CV-type data from a battery, something that would be hazardous if done conventionally using a voltage ramp.

Repeatable, low-error EIS measurements at ELFs are essential for inferring battery ECM components, including constant phase elements (CPEs). The fractional order of a CPE is linked to battery state of health (SoH) and energy efficiency. This thesis shows that efficiency measurements with waveforms representative of real battery usage can be used to track battery SoH accurately.

text: Characterisation and prediction of state of health of rechargeable batteries Electrochemical impedance spectroscopy (EIS) is used extensively in battery research, but usually at frequencies that do not reflect real-world usage patterns. This has resulted in equivalent circuit models (ECMs) that are over-complicated, and suboptimal battery management systems. It is logical to measure batteries at frequencies reflecting their daily or weekly charge-discharge cycles, i.e., of the order of microhertz. This is generally not done, however, because of difficulties that include extreme measurement durations and the need for care to avoid issues such as charge distribution problems, charge drift, and the risk of overcharging or flattening the battery. This research demonstrates the feasibility of extra-low frequency (ELF) EIS measurement using standard, non-specialised measurement equipment, and the optimisation of frequency domain data through the superimposition of small-signal measurement tones on larger square wave currents.

Study of charge movement rates in the frequency domain and voltage responses in the time domain in batteries indicates connections between voltage sweep rate in cyclic voltammetry (CV) and current magnitude in incremental capacity analysis (ICA). The key factor determining what the investigator sees, e.g., reversibility  of electrode processes or evidence of individual electrochemical reactions, is rate of movement of charge. Thus, controlled current can be used to obtain CV-type data from a battery, something that would be hazardous if done conventionally using a voltage ramp.

Repeatable, low-error EIS measurements at ELFs are essential for inferring battery ECM components, including constant phase elements (CPEs). The fractional order of a CPE is linked to battery state of health (SoH) and energy efficiency. This thesis shows that efficiency measurements with waveforms representative of real battery usage can be used to track battery SoH accurately.

year: 2024

title: Comments on the current state and role of marketing scholarship

authors: Varey, Richard J.

subjects: marketing

abstract: Once again, Professor Gummesson’s incisive critique cuts through surface gloss to the heart and soul of the marketing academy. It is purpose, and not only technique that matters. Professor Gummesson raises issues about the mass production of scholarship that remain largely unspoken, even if they are recognized.

text: Comments on the current state and role of marketing scholarship Once again, Professor Gummesson’s incisive critique cuts through surface gloss to the heart and soul of the marketing academy. It is purpose, and not only technique that matters. Professor Gummesson raises issues about the mass production of scholarship that remain largely unspoken, even if they are recognized.

year: 2010

title: Rewi Mokena: youngest son of Mokena Hou

authors: Hart, Philip

abstract: The youngest child of Mokena Hou, Rewi Mokena moved from place to place when young, finally settling permanently at Te Aroha. Having received some education, he was fluent in English. Like the typical rangatira of the time, he acquired interests in several blocks of land, obtained income from these in the short term, but because of financial difficulties was brought before the court several times. 
His involvement in gold mining started in a small way in 1875. Five years later, he would assist Hone Werahiko to prospect Te Aroha – and to fend off inquisitive Pakeha. He invested in claims in all of the three areas where gold was found.
By the twentieth century, Rewi was the most important rangatira at Te Aroha, and had wider influence, assisting the King Movement to seek redress for lost land. From a young age he participated in Pakeha society, notably as a rugby player, and became a prominent Mormon. His complicated private life, including bigamy and a wife’s attempted suicide because of his adultery, did not lower his high standing in Maori society nor damage his popularity with Pakeha.

text: Rewi Mokena: youngest son of Mokena Hou The youngest child of Mokena Hou, Rewi Mokena moved from place to place when young, finally settling permanently at Te Aroha. Having received some education, he was fluent in English. Like the typical rangatira of the time, he acquired interests in several blocks of land, obtained income from these in the short term, but because of financial difficulties was brought before the court several times. 
His involvement in gold mining started in a small way in 1875. Five years later, he would assist Hone Werahiko to prospect Te Aroha – and to fend off inquisitive Pakeha. He invested in claims in all of the three areas where gold was found.
By the twentieth century, Rewi was the most important rangatira at Te Aroha, and had wider influence, assisting the King Movement to seek redress for lost land. From a young age he participated in Pakeha society, notably as a rugby player, and became a prominent Mormon. His complicated private life, including bigamy and a wife’s attempted suicide because of his adultery, did not lower his high standing in Maori society nor damage his popularity with Pakeha.

year: 2016