title: Multiple return separation for a full-field ranger via continuous waveform modelling

authors: Godbaz, John Peter

subjects: lidar

abstract: We present two novel Poisson noise Maximum Likelihood based methods for identifying the individual returns within mixed pixels for Amplitude Modulated Continuous Wave rangers. These methods use the convolutional relationship between signal returns and the recorded data to determine the number, range and intensity of returns within a pixel. One method relies on a continuous piecewise truncated-triangle model for the beat waveform and the other on linear interpolation between translated versions of a sampled waveform. In the single return case both methods provide an improvement in ranging precision over standard Fourier transform based methods and a decrease in overall error in almost every case. We find that it is possible to discriminate between two light sources within a pixel, but local minima and scattered light have a significant impact on ranging precision. Discrimination of two returns requires the ability to take samples at less than 90 phase shifts.

text: Multiple return separation for a full-field ranger via continuous waveform modelling We present two novel Poisson noise Maximum Likelihood based methods for identifying the individual returns within mixed pixels for Amplitude Modulated Continuous Wave rangers. These methods use the convolutional relationship between signal returns and the recorded data to determine the number, range and intensity of returns within a pixel. One method relies on a continuous piecewise truncated-triangle model for the beat waveform and the other on linear interpolation between translated versions of a sampled waveform. In the single return case both methods provide an improvement in ranging precision over standard Fourier transform based methods and a decrease in overall error in almost every case. We find that it is possible to discriminate between two light sources within a pixel, but local minima and scattered light have a significant impact on ranging precision. Discrimination of two returns requires the ability to take samples at less than 90 phase shifts.

year: 2009

title: Distinguishability of rechargeable battery equivalent circuit models

authors: Poihipi, Eden Kathleen

subjects: ECM

abstract: The contention made by Berthier et al. - that competing fractional-element equivalent- circuit models of battery cells are indistinguishable in the presence of noise - is revisited in this work. A set of six equivalent circuit models (ECMs) were chosen as a subset of West- erhoff’s generalised ECM from 2016. These six ECMs had increasing complexity, and gave a simulated output similar to that of an idealised Lithium battery impedance spec- trum. By extending the frequency range of Berthier, using methods suggested by both Mauracher & Karden, and Hasan & Scott, sets of simulated electrochemical impedance spectra (EIS) are generated. A Nelder-Mead based optimisation method, which em- ploys multiple restarts, is used to fit each ECM to the sets simulated data. The data was produced with 0%, 1%, 3% and 5% noise. The optimisations showed that all six ECMs were distinguishable at 0% noise, but as the noise increased - distinguishability is lost. Typically a 4-element ECM is shown to model the simulated data with preci- sion which is comparable to the error in the data. When optimising the ECMs against measured data (measured with an Egilent 66332A, E5270 and a Keithley 2460A) from INR and NCA batteries, it is seen that the 3-element ECMs are an adequate model. However there is some variation between the two battery chemistries. Battery ageing and the measurement system used also contribute to variation in which ECM models the data best. Further work on this project should include repeating this fitting method on different battery chemistries, and collating and fitting ECMs to a battery which is measured at different points as it ages.

text: Distinguishability of rechargeable battery equivalent circuit models The contention made by Berthier et al. - that competing fractional-element equivalent- circuit models of battery cells are indistinguishable in the presence of noise - is revisited in this work. A set of six equivalent circuit models (ECMs) were chosen as a subset of West- erhoff’s generalised ECM from 2016. These six ECMs had increasing complexity, and gave a simulated output similar to that of an idealised Lithium battery impedance spec- trum. By extending the frequency range of Berthier, using methods suggested by both Mauracher & Karden, and Hasan & Scott, sets of simulated electrochemical impedance spectra (EIS) are generated. A Nelder-Mead based optimisation method, which em- ploys multiple restarts, is used to fit each ECM to the sets simulated data. The data was produced with 0%, 1%, 3% and 5% noise. The optimisations showed that all six ECMs were distinguishable at 0% noise, but as the noise increased - distinguishability is lost. Typically a 4-element ECM is shown to model the simulated data with preci- sion which is comparable to the error in the data. When optimising the ECMs against measured data (measured with an Egilent 66332A, E5270 and a Keithley 2460A) from INR and NCA batteries, it is seen that the 3-element ECMs are an adequate model. However there is some variation between the two battery chemistries. Battery ageing and the measurement system used also contribute to variation in which ECM models the data best. Further work on this project should include repeating this fitting method on different battery chemistries, and collating and fitting ECMs to a battery which is measured at different points as it ages.

year: 2023

title: Putting the draft learning progression framework - Maori in the New Zealand Curriculum - to work: An Illustration

authors: Johnson, Diane

subjects: Māori language education

abstract: How language curricula are implemented in the classroom is of critical importance. Here, we take one achievement objective from the draft Learning Progression Framework for Māori in mainstream classes and demonstrate one way in which it can be realised as a core integrated skills lesson, that is, as a lesson that introduces new language (core lesson) through all four skills - reading, writing, listening and speaking (an integrated skills lesson). The lesson is preceded by a discussion of the type of planning that accompanies the implementation of language curricula.

text: Putting the draft learning progression framework - Maori in the New Zealand Curriculum - to work: An Illustration How language curricula are implemented in the classroom is of critical importance. Here, we take one achievement objective from the draft Learning Progression Framework for Māori in mainstream classes and demonstrate one way in which it can be realised as a core integrated skills lesson, that is, as a lesson that introduces new language (core lesson) through all four skills - reading, writing, listening and speaking (an integrated skills lesson). The lesson is preceded by a discussion of the type of planning that accompanies the implementation of language curricula.

year: 2003-09