title: Human visual-vestibular interaction during curvilinear motion in VR

authors: Garnett, Aden C.

abstract: When people move through the world they use retinal image motion to form an estimate of self-motion, although how this is achieved is not yet fully understood. Furthermore, the process is not fool-proof and many conditions create incorrect percepts of self-motion. In particular, experiencing rotation makes it difficult for humans to correctly perceive heading during movement from visual input alone. 

Here we re-examined human perception of rotation during true and simulated curvilinear motion. Broadly, this was done by simulating movement along various paths using currently available head-mounted stereoscopic virtual reality displays. These displays overcome many of the shortcomings of historical equipment but also represent a significant departure from established setups. As such, the first two experiments, presented together in Chapter 2, replicated experiments from Banks, Ehrlich, Backus, and Crowell (1996) and Crowell, Banks, Shenoy, and Andersen (1998). This was to aid in determining the suitability of consumer-grade virtual reality headsets for self-motion perception research and to provide a point of comparison between this thesis and historical works. 

Following confirmation that the VR devices were suitable for research we developed a virtual line-based bendable response tool. This tool made use of tracked hand controllers to facilitate fast and intuitive reporting of self-motion perception without confounding heading and rotation perception errors. Using this tool we confirmed reports of curvilinear motion perception during linear travel with rotation. We then measured perception of heading and curvature during travel on linear paths of increasingly eccentric heading, finding that eccentric headings elicited perceptions of curvature. We also measured perceptions of travel along curvilinear paths so that a model of human visual-vestibular interaction \cite{perrone2018visual} as it applies to heading perception could be tested against participant performance. Finally, predictions from this model prompted us to measure curvilinear path perception while using a rotating chair that allowed us to provide a rough congruent vestibular signal.

Overall, we found consistent large individual differences in perception across all motion types, although each individual's perceptions were internally consistent. Furthermore, we found that participants perceived curvature while travelling on not only curvilinear paths, but also on linear paths with rotation and linear paths with eccentric headings. The tested model, as implemented, matched participant results well, proving able to explain the majority of the individual differences. Finally, we found that providing a rough congruent vestibular signal resulted in participants perceiving less curved paths compared to when the vestibular signal indicated no rotation.

text: Human visual-vestibular interaction during curvilinear motion in VR When people move through the world they use retinal image motion to form an estimate of self-motion, although how this is achieved is not yet fully understood. Furthermore, the process is not fool-proof and many conditions create incorrect percepts of self-motion. In particular, experiencing rotation makes it difficult for humans to correctly perceive heading during movement from visual input alone. 

Here we re-examined human perception of rotation during true and simulated curvilinear motion. Broadly, this was done by simulating movement along various paths using currently available head-mounted stereoscopic virtual reality displays. These displays overcome many of the shortcomings of historical equipment but also represent a significant departure from established setups. As such, the first two experiments, presented together in Chapter 2, replicated experiments from Banks, Ehrlich, Backus, and Crowell (1996) and Crowell, Banks, Shenoy, and Andersen (1998). This was to aid in determining the suitability of consumer-grade virtual reality headsets for self-motion perception research and to provide a point of comparison between this thesis and historical works. 

Following confirmation that the VR devices were suitable for research we developed a virtual line-based bendable response tool. This tool made use of tracked hand controllers to facilitate fast and intuitive reporting of self-motion perception without confounding heading and rotation perception errors. Using this tool we confirmed reports of curvilinear motion perception during linear travel with rotation. We then measured perception of heading and curvature during travel on linear paths of increasingly eccentric heading, finding that eccentric headings elicited perceptions of curvature. We also measured perceptions of travel along curvilinear paths so that a model of human visual-vestibular interaction \cite{perrone2018visual} as it applies to heading perception could be tested against participant performance. Finally, predictions from this model prompted us to measure curvilinear path perception while using a rotating chair that allowed us to provide a rough congruent vestibular signal.

Overall, we found consistent large individual differences in perception across all motion types, although each individual's perceptions were internally consistent. Furthermore, we found that participants perceived curvature while travelling on not only curvilinear paths, but also on linear paths with rotation and linear paths with eccentric headings. The tested model, as implemented, matched participant results well, proving able to explain the majority of the individual differences. Finally, we found that providing a rough congruent vestibular signal resulted in participants perceiving less curved paths compared to when the vestibular signal indicated no rotation.

year: 2020

title: Innovative cold-formed steel nested tapered box section portal frames with bolted-side plate joints

authors: Paul, Bikram

abstract: Nested tapered box (NTB) portal frames made entirely of cold-formed steel (CFS) are widely used in New Zealand. Shahmohammadi (2019) recently described a full-scale test of such a system. The tested frame had a span of 18.16 meters and a height to the eaves of 4.27 meters. The joints of this NTB portal frame were rigid, constructed with bolted end plates. However, bolted end plate joints can be expensive due to the full penetration butt weld. This thesis proposes an alternative jointing system that uses bolted-side plates. The numerical work conducted in this study yields the following findings:
•	A shell finite element (FE) model was developed and validated using previously conducted full-scale portal frame tests. This validated model was then employed to compare the performance of bolted-side plate joints with bolted end-plate joints. The analysis revealed that a portal frame with 10 mm thick bolted side plates could sustain the same load as an NTB portal frame with bolted end-plate joints. Increasing the thickness of the bolted-side plates from 10 mm to 16 mm resulted in a 20% increase in load-carrying capacity. This improvement was due to the confinement effect provided by the side plates, which reduced the slenderness ratio near the eaves joint. However, the NTB portal frame with bolted-side plates exhibited greater apex displacement compared to the frame with bolted end-plate joints. 
•	FE models were developed for both the eaves and apex joints of the NTB portal frame.  A parametric study was then carried out involving 1,000 FE models. Using FE models, design equations are proposed for the moment capacities of the eaves and apex bolted side plates, accounting for both opening and closing moments under partial restraint.
•	A parametric study was conducted using the developed design method on eight models, considering a range of spans from 25m to 40m and eaves heights from 5.5m to 6.25m, with a consistent frame spacing of 7.5m. The results showed that portal frames with bolted-side plates can carry on average 7% more load compared to those with bolted end plate joints.
•	A methodology was presented to predict the load-carrying capacity of portal frames with back-to-back channel sections. It was shown that the predicted vertical loads from the proposed approach were, on average, within 1% (on an average) of the FEA results for portal frames. The same approach was applied to NTB portal frames through worked examples in Appendix B and C, demonstrating good accuracy.

text: Innovative cold-formed steel nested tapered box section portal frames with bolted-side plate joints Nested tapered box (NTB) portal frames made entirely of cold-formed steel (CFS) are widely used in New Zealand. Shahmohammadi (2019) recently described a full-scale test of such a system. The tested frame had a span of 18.16 meters and a height to the eaves of 4.27 meters. The joints of this NTB portal frame were rigid, constructed with bolted end plates. However, bolted end plate joints can be expensive due to the full penetration butt weld. This thesis proposes an alternative jointing system that uses bolted-side plates. The numerical work conducted in this study yields the following findings:
•	A shell finite element (FE) model was developed and validated using previously conducted full-scale portal frame tests. This validated model was then employed to compare the performance of bolted-side plate joints with bolted end-plate joints. The analysis revealed that a portal frame with 10 mm thick bolted side plates could sustain the same load as an NTB portal frame with bolted end-plate joints. Increasing the thickness of the bolted-side plates from 10 mm to 16 mm resulted in a 20% increase in load-carrying capacity. This improvement was due to the confinement effect provided by the side plates, which reduced the slenderness ratio near the eaves joint. However, the NTB portal frame with bolted-side plates exhibited greater apex displacement compared to the frame with bolted end-plate joints. 
•	FE models were developed for both the eaves and apex joints of the NTB portal frame.  A parametric study was then carried out involving 1,000 FE models. Using FE models, design equations are proposed for the moment capacities of the eaves and apex bolted side plates, accounting for both opening and closing moments under partial restraint.
•	A parametric study was conducted using the developed design method on eight models, considering a range of spans from 25m to 40m and eaves heights from 5.5m to 6.25m, with a consistent frame spacing of 7.5m. The results showed that portal frames with bolted-side plates can carry on average 7% more load compared to those with bolted end plate joints.
•	A methodology was presented to predict the load-carrying capacity of portal frames with back-to-back channel sections. It was shown that the predicted vertical loads from the proposed approach were, on average, within 1% (on an average) of the FEA results for portal frames. The same approach was applied to NTB portal frames through worked examples in Appendix B and C, demonstrating good accuracy.

year: 2025

title: Foresight in hindsight: Visions of the future from Julius Vogel, Āpirana Ngata, Truby King, and Ettie Rout, 1889-1923

authors: Lemberg, Nicola Johanna

subjects: history

abstract: This thesis examines seven future-focused texts authored by four New Zealanders: Julius Vogel, Āpirana Ngata, Truby King, and Ettie Rout. ‘The future’ is a neglected lens for historical research and this thesis explores the value of such an approach, using New Zealand society from the 1880s and to the 1920s as a case study. A methodological combination of textual analysis, biography, and historical contexts, including consideration of print culture, allows for nuanced examination of depictions of the future, and suggests such connections are vital to fully understanding histories of the future. This research serves as a framework to inform further exploration of historical future imaginings, either in New Zealand or in other geographic or temporal contexts.

From Vogel’s novel Anno Domini 2000 (1889) to Ngata’s 1892 essay The Past and Future of the Maori to King’s and Rout’s twentieth-century guidebooks on the care of babies and the use of contraception, the four authors utilize various textual forms to communicate their imagined future, and commonly frame their ideas within concepts of utopia and dystopia. This thesis compares the futures depicted by male and female authors, and those emerging from Māori and Pākehā cultural contexts. It examines futures envisioned by politicians, community leaders, and ostracized individuals. Shaped by preoccupations with empire, gender, and identity, these future-focused texts highlight relationships between national and global spaces. This in turn allows for a fresh exploration of New Zealand’s past, and especially the country’s colonial histories.

text: Foresight in hindsight: Visions of the future from Julius Vogel, Āpirana Ngata, Truby King, and Ettie Rout, 1889-1923 This thesis examines seven future-focused texts authored by four New Zealanders: Julius Vogel, Āpirana Ngata, Truby King, and Ettie Rout. ‘The future’ is a neglected lens for historical research and this thesis explores the value of such an approach, using New Zealand society from the 1880s and to the 1920s as a case study. A methodological combination of textual analysis, biography, and historical contexts, including consideration of print culture, allows for nuanced examination of depictions of the future, and suggests such connections are vital to fully understanding histories of the future. This research serves as a framework to inform further exploration of historical future imaginings, either in New Zealand or in other geographic or temporal contexts.

From Vogel’s novel Anno Domini 2000 (1889) to Ngata’s 1892 essay The Past and Future of the Maori to King’s and Rout’s twentieth-century guidebooks on the care of babies and the use of contraception, the four authors utilize various textual forms to communicate their imagined future, and commonly frame their ideas within concepts of utopia and dystopia. This thesis compares the futures depicted by male and female authors, and those emerging from Māori and Pākehā cultural contexts. It examines futures envisioned by politicians, community leaders, and ostracized individuals. Shaped by preoccupations with empire, gender, and identity, these future-focused texts highlight relationships between national and global spaces. This in turn allows for a fresh exploration of New Zealand’s past, and especially the country’s colonial histories.

year: 2024