title: Augmenting NIR spectra in deep regression to improve calibration

authors: Wohlers, Mark W.

subjects: computer science

abstract: Deep learning, particularly with convolutional neural networks, shows promise in modelling near-infrared spectroscopy (NIRS), but the lack of robust generalisation across instruments often affects performance in practice. Here, we investigate a method to increase the robustness of this approach. The proposed method involves using a simple data augmentation technique during the training process. The performance of convolutional neural network regression is compared to partial least squares regression (PLSR) using kiwifruit data collected from multiple handheld devices over three seasons and mango data collected from a single device over four seasons. The results suggest that data augmentation for NIR spectra can prevent overfitting. In particular, augmenting the training data to mimic spectra collected over multiple devices results in a neural network model with improved performance over PLSR.

text: Augmenting NIR spectra in deep regression to improve calibration Deep learning, particularly with convolutional neural networks, shows promise in modelling near-infrared spectroscopy (NIRS), but the lack of robust generalisation across instruments often affects performance in practice. Here, we investigate a method to increase the robustness of this approach. The proposed method involves using a simple data augmentation technique during the training process. The performance of convolutional neural network regression is compared to partial least squares regression (PLSR) using kiwifruit data collected from multiple handheld devices over three seasons and mango data collected from a single device over four seasons. The results suggest that data augmentation for NIR spectra can prevent overfitting. In particular, augmenting the training data to mimic spectra collected over multiple devices results in a neural network model with improved performance over PLSR.

year: 2023

title: Comparison of spatial prediction techniques for developing Pinus radiata productivity surfaces across New Zealand

authors: Palmer, David John

subjects: plantation forestry

abstract: Spatial interpolation is frequently used to predict values across a landscape enabling the spatial variation and patterns of a property to be quantified. Inverse distance weighting (IDW), ordinary kriging (OK), regression kriging (RK), and partial least squares (PLS) regression are interpolation techniques typically used where the region of interest's spatial extent is relatively small and observations are numerous and regularly spaced. In the current era of data ‘mining’ and utilisation of sparse data, the above criteria are not always fully met, increasing model uncertainties. Furthermore, regression modelling and kriging techniques require good judgement, experience, and expertise by the practitioner compared with IDW with its more rudimentary approach. In this study we compared spatial predictions derived from IDW, PLS, RK, and OK for Pinus radiata volume mean annual increment (referred to as 300 Index) and mean top height at age twenty (referred to as Site Index) across New Zealand using cross-validation techniques. Validation statistics (RMSE, ME, and R2) show that RK, OK, and IDW provided predictions that were less biased and of greater accuracy than PLS predictions. Standard deviation of rank (SDR) and mean rank (MR) validation statistics showed similar results with OK the most consistent (SDR) predictor, whereas RK had the lowest mean rank (MR), closely followed by IDW. However, the mean performance rankings for validation observations classified according to their distance to the nearest model data point indicate that although PLS provided the poorest predictions at relatively close separation distances (<2 km), in the medium range ( 4–8 km) performance was of similar ranking to that of the other techniques, and at greater separation distances PLS outperformed the other techniques. Maps illustrating the spatial variation of P. radiata forest productivity are provided.

text: Comparison of spatial prediction techniques for developing Pinus radiata productivity surfaces across New Zealand Spatial interpolation is frequently used to predict values across a landscape enabling the spatial variation and patterns of a property to be quantified. Inverse distance weighting (IDW), ordinary kriging (OK), regression kriging (RK), and partial least squares (PLS) regression are interpolation techniques typically used where the region of interest's spatial extent is relatively small and observations are numerous and regularly spaced. In the current era of data ‘mining’ and utilisation of sparse data, the above criteria are not always fully met, increasing model uncertainties. Furthermore, regression modelling and kriging techniques require good judgement, experience, and expertise by the practitioner compared with IDW with its more rudimentary approach. In this study we compared spatial predictions derived from IDW, PLS, RK, and OK for Pinus radiata volume mean annual increment (referred to as 300 Index) and mean top height at age twenty (referred to as Site Index) across New Zealand using cross-validation techniques. Validation statistics (RMSE, ME, and R2) show that RK, OK, and IDW provided predictions that were less biased and of greater accuracy than PLS predictions. Standard deviation of rank (SDR) and mean rank (MR) validation statistics showed similar results with OK the most consistent (SDR) predictor, whereas RK had the lowest mean rank (MR), closely followed by IDW. However, the mean performance rankings for validation observations classified according to their distance to the nearest model data point indicate that although PLS provided the poorest predictions at relatively close separation distances (<2 km), in the medium range ( 4–8 km) performance was of similar ranking to that of the other techniques, and at greater separation distances PLS outperformed the other techniques. Maps illustrating the spatial variation of P. radiata forest productivity are provided.

year: 2009

title: Poetic lives: Verse biography in Aotearoa New Zealand

authors: Anderson-O'Connor, Aimee-Jane

subjects: Verse

abstract: Bringing together a selection of Aotearoa New Zealand verse biographies, and drawing on perspectives deriving from decolonizing methodologies, and from historical and feminist revision and reclamation, as well as my own experience as a creative practitioner, this thesis explores verse biography in Aotearoa New Zealand, with special reference to common thematic and personal preoccupations, and the settings in which these play out.  I am led in this research by a few key questions. What techniques are available to the verse biographer, and what opportunities for innovation and intervention do these techniques afford? What limitations remain? What key settings shape and are shaped by the lives of those who live here? What can we learn by exploring the relationship between the individual life story and the cultural stories which take shape in what Philip Fisher has called the ‘privileged settings’ of any national literature? I focus in particular on a selection of longer verse biographies: Allen Curnow’s ‘An Abominable Temper’ (1973), Ian Wedde’s ‘A Ballad for Worser Heberley’ (1993), Robert Sullivan’s Captain Cook in the Underworld (2002), Airini Beautrais’s Dear Neil Roberts (2014), Chris Tse’s How to be Dead in a Year of Snakes (2014), Gregory Kan’s This Paper Boat (2016), Karen Zelas’s The Trials of Minnie Dean: A Verse Biography (2017), and Nina Powles’s collection of chapbooks collectively titled Luminescent (2017). I have chosen longer works because of the scope they offer to trace the broader sense of the life story and pick up on imagery and voices which repeat and echo within the texts. I am also interested in the way that Aotearoa New Zealand verse biographers often extend their subject’s life story beyond the barrier of death and imagine their subjects’ afterlives in sensory poetic terms. While this selection is diverse, and showcases a wide range of subject matter, poetic approach and voices, each of these verse biographies dramatizes the subject position of the poet, and partakes in a poetics of intersectional revision and reclamation. 
 My exegesis identifies and explores the fundamental role of setting in the canon and analyses the energizing concerns that verse biographers unpack in these settings. I am interested in the ways that Aotearoa New Zealand verse biographers maintain attention to key local settings throughout their works, and critically engage with the cultural stories which persist in and around them. I am especially interested in the way these poetic explorations afford space for decolonial and feminist approaches. Four major settings appear often. The beach is a space of encounter in which ongoing processes of colonisation and crossing unfold. The home is marked by instability and hidden harm, in which domestic disorder is unearthed. The police station is exposed as a space of class and gender power imbalance which informs law making and enforcement. The beyond constitutes a liminal space of exchange and unrest, as the poets grapple with cultural exchange and complexities of life and death.
The final portion of my thesis takes the form of a creative practice component. It consists of a verse biography titled Keepsake, centred on the lives of my paternal grandparents, Kevin Buxton O’Connor and Mary Helen O’Connor (née Fryer). It engages explicitly with the issues raised in the analytical component of my thesis. Keepsake is a collection shaped indelibly by the sudden death of my grandmother midway through my thesis, and my experience of weathering the seasons of grief with my grandfather, and our shared attempts to find the words to hold tight to her life. Like many of the other verse biographies in Aotearoa New Zealand, it operates as a poetic and historiographic record of my research process and the time in which the thesis was written. It has allowed me to deepen my understanding of the ways in which verse biography allows for a simultaneous autobiographical exploration, examining the role of the verse biographer as researcher and intermediary between the past and the present. The process has especially strengthened my appreciation for verse biography as a form which takes us into the beyond and affords a space where we might speak to the dead and hold space for an answer, where we might make a home of language, ripe for haunting.

text: Poetic lives: Verse biography in Aotearoa New Zealand Bringing together a selection of Aotearoa New Zealand verse biographies, and drawing on perspectives deriving from decolonizing methodologies, and from historical and feminist revision and reclamation, as well as my own experience as a creative practitioner, this thesis explores verse biography in Aotearoa New Zealand, with special reference to common thematic and personal preoccupations, and the settings in which these play out.  I am led in this research by a few key questions. What techniques are available to the verse biographer, and what opportunities for innovation and intervention do these techniques afford? What limitations remain? What key settings shape and are shaped by the lives of those who live here? What can we learn by exploring the relationship between the individual life story and the cultural stories which take shape in what Philip Fisher has called the ‘privileged settings’ of any national literature? I focus in particular on a selection of longer verse biographies: Allen Curnow’s ‘An Abominable Temper’ (1973), Ian Wedde’s ‘A Ballad for Worser Heberley’ (1993), Robert Sullivan’s Captain Cook in the Underworld (2002), Airini Beautrais’s Dear Neil Roberts (2014), Chris Tse’s How to be Dead in a Year of Snakes (2014), Gregory Kan’s This Paper Boat (2016), Karen Zelas’s The Trials of Minnie Dean: A Verse Biography (2017), and Nina Powles’s collection of chapbooks collectively titled Luminescent (2017). I have chosen longer works because of the scope they offer to trace the broader sense of the life story and pick up on imagery and voices which repeat and echo within the texts. I am also interested in the way that Aotearoa New Zealand verse biographers often extend their subject’s life story beyond the barrier of death and imagine their subjects’ afterlives in sensory poetic terms. While this selection is diverse, and showcases a wide range of subject matter, poetic approach and voices, each of these verse biographies dramatizes the subject position of the poet, and partakes in a poetics of intersectional revision and reclamation. 
 My exegesis identifies and explores the fundamental role of setting in the canon and analyses the energizing concerns that verse biographers unpack in these settings. I am interested in the ways that Aotearoa New Zealand verse biographers maintain attention to key local settings throughout their works, and critically engage with the cultural stories which persist in and around them. I am especially interested in the way these poetic explorations afford space for decolonial and feminist approaches. Four major settings appear often. The beach is a space of encounter in which ongoing processes of colonisation and crossing unfold. The home is marked by instability and hidden harm, in which domestic disorder is unearthed. The police station is exposed as a space of class and gender power imbalance which informs law making and enforcement. The beyond constitutes a liminal space of exchange and unrest, as the poets grapple with cultural exchange and complexities of life and death.
The final portion of my thesis takes the form of a creative practice component. It consists of a verse biography titled Keepsake, centred on the lives of my paternal grandparents, Kevin Buxton O’Connor and Mary Helen O’Connor (née Fryer). It engages explicitly with the issues raised in the analytical component of my thesis. Keepsake is a collection shaped indelibly by the sudden death of my grandmother midway through my thesis, and my experience of weathering the seasons of grief with my grandfather, and our shared attempts to find the words to hold tight to her life. Like many of the other verse biographies in Aotearoa New Zealand, it operates as a poetic and historiographic record of my research process and the time in which the thesis was written. It has allowed me to deepen my understanding of the ways in which verse biography allows for a simultaneous autobiographical exploration, examining the role of the verse biographer as researcher and intermediary between the past and the present. The process has especially strengthened my appreciation for verse biography as a form which takes us into the beyond and affords a space where we might speak to the dead and hold space for an answer, where we might make a home of language, ripe for haunting.

year: 2022