title: Effects of lubrication on the powder metallurgy processing of titanium

authors: Lou, Jia

subjects: Compaction

abstract: The role of lubrication on the consolidation behaviour of titanium powder, density increase and change in microstructure on subsequent sintering was investigated. HDH titanium powder mixed with 0-2wt% stearic acid or magnesium stearate was cold compacted. It was found that 0.3-0.6wt% of internal lubricant significantly improves the compressibility. However, more than 0.6wt% of lubricant aids the densification in the low-pressure region but limits the maximum density at high pressure. Moreover, 0.3-0.6wt% of lubricant offers a more uniform density distribution to the powder compact, while greater than 0.6wt% of lubricant leads to a segregation of lubricant in the surface region. The shape retention, ejection behaviour, de-lubrication behaviour and sintered properties were also studied in this work.

text: Effects of lubrication on the powder metallurgy processing of titanium The role of lubrication on the consolidation behaviour of titanium powder, density increase and change in microstructure on subsequent sintering was investigated. HDH titanium powder mixed with 0-2wt% stearic acid or magnesium stearate was cold compacted. It was found that 0.3-0.6wt% of internal lubricant significantly improves the compressibility. However, more than 0.6wt% of lubricant aids the densification in the low-pressure region but limits the maximum density at high pressure. Moreover, 0.3-0.6wt% of lubricant offers a more uniform density distribution to the powder compact, while greater than 0.6wt% of lubricant leads to a segregation of lubricant in the surface region. The shape retention, ejection behaviour, de-lubrication behaviour and sintered properties were also studied in this work.

year: 2012

title: Duty factor is a viable measure to classify spontaneous running forms

authors: Patoz, Aurélien

subjects: biomechanics

abstract: Runners were classified using two different methods based on their spontaneous running form: (1) subjectively using the V®score from the Volodalen® scale, leading to terrestrial and aerial groups; and (2) objectively using the duty factor (DF), leading to high (DFhigh) and low (DFlow) DF groups. This study aimed to compare these two classification schemes. Eighty-nine runners were divided in two groups using the V®score (VOL groups) and were also ranked according to their DF. They ran on a treadmill at 12 km·h⁻¹ with simultaneous recording of running kinematics, using a three-dimensional motion capture system. DF was computed from data as the ratio of ground contact time to stride time. The agreement (95% confidence interval) between VOL and DF groups was 79.8% (69.9%, 87.6%), with relatively high sensitivity (81.6% (68.0%, 91.2%)) and specificity (77.5% (61.6%, 89.2%)). Our results suggest that the DF and V®score reflect similar constructs and lead to similar subgroupings of spontaneous running form (aerial runners if DF < 27.6% and terrestrial runners if DF > 28.8% at 12 km·h⁻¹). These results suggest that DF could be a useful objective measure to monitor real-time changes in spontaneous running form using wearable technology. As a forward-looking statement, spontaneous changes in running form during racing or training could assist in identifying fatigue or changes in environmental conditions, allowing for a better understanding of runners.

text: Duty factor is a viable measure to classify spontaneous running forms Runners were classified using two different methods based on their spontaneous running form: (1) subjectively using the V®score from the Volodalen® scale, leading to terrestrial and aerial groups; and (2) objectively using the duty factor (DF), leading to high (DFhigh) and low (DFlow) DF groups. This study aimed to compare these two classification schemes. Eighty-nine runners were divided in two groups using the V®score (VOL groups) and were also ranked according to their DF. They ran on a treadmill at 12 km·h⁻¹ with simultaneous recording of running kinematics, using a three-dimensional motion capture system. DF was computed from data as the ratio of ground contact time to stride time. The agreement (95% confidence interval) between VOL and DF groups was 79.8% (69.9%, 87.6%), with relatively high sensitivity (81.6% (68.0%, 91.2%)) and specificity (77.5% (61.6%, 89.2%)). Our results suggest that the DF and V®score reflect similar constructs and lead to similar subgroupings of spontaneous running form (aerial runners if DF < 27.6% and terrestrial runners if DF > 28.8% at 12 km·h⁻¹). These results suggest that DF could be a useful objective measure to monitor real-time changes in spontaneous running form using wearable technology. As a forward-looking statement, spontaneous changes in running form during racing or training could assist in identifying fatigue or changes in environmental conditions, allowing for a better understanding of runners.

year: 2019

title: New Zealand history is Maori history: Tikanga as the ethical foundation of historical scholarship In Aotearoa New Zealand

authors: Mahuika, Nepia

subjects: Arts & Humanities

abstract: IT SHOULD COME AS NO SURPRISE TO FIND that New Zealand history is Māori history. In 1987 when Tipene O’Regan stated that the ‘the past belongs to all New Zealanders, but first it is ours’, he was drawing attention to New Zealand history’s foundation in Māori history.1 Thinking about New Zealand history as Māori history does not mean denying the histories of European, Asian and Pasifika immigrants, but draws attention to the notion that ‘settler’ aspirations to claim ‘Aotearoa’ as home occur within a much broader narrative of indigenous occupation and struggle.2 Indeed, how can New Zealand history be the story of ‘here’ when it has ‘othered’ indigenous narratives that speak to the heart of what it is to belong in the land of the long white cloud? Yes, New Zealand history is Māori history – and that presents a problem for tangata whenua self-determination. Likewise, for Pākehā, it is an issue because until New Zealand history recognizes and enables the centrality of Māori history it will always fail to articulate the collective ‘us’ that is so often assumed in the discourse of ‘full and final settlement’.3 In its current form it will never be able to ethically or adequately account for the shaping of a New Zealand identity that finds ‘composure’ in the story of how Pākehā became ‘native’ New Zealanders.4 For Māori, these issues are keenly felt, because while New Zealand history has always been about us, it has predominantly been articulated on the colonizers’ terms. In the ‘discursive constructions’ that are New Zealand histories, the indigenous have regularly been culturally appropriated, dislocated and misrepresented.5 Even when Māori have turned their back on the writing of New Zealand history it has been, and will still be, a history of being or becoming ‘native’. Yes, New Zealand history is Māori history – so why does it feel like the story of Pākehā settlers?

text: New Zealand history is Maori history: Tikanga as the ethical foundation of historical scholarship In Aotearoa New Zealand IT SHOULD COME AS NO SURPRISE TO FIND that New Zealand history is Māori history. In 1987 when Tipene O’Regan stated that the ‘the past belongs to all New Zealanders, but first it is ours’, he was drawing attention to New Zealand history’s foundation in Māori history.1 Thinking about New Zealand history as Māori history does not mean denying the histories of European, Asian and Pasifika immigrants, but draws attention to the notion that ‘settler’ aspirations to claim ‘Aotearoa’ as home occur within a much broader narrative of indigenous occupation and struggle.2 Indeed, how can New Zealand history be the story of ‘here’ when it has ‘othered’ indigenous narratives that speak to the heart of what it is to belong in the land of the long white cloud? Yes, New Zealand history is Māori history – and that presents a problem for tangata whenua self-determination. Likewise, for Pākehā, it is an issue because until New Zealand history recognizes and enables the centrality of Māori history it will always fail to articulate the collective ‘us’ that is so often assumed in the discourse of ‘full and final settlement’.3 In its current form it will never be able to ethically or adequately account for the shaping of a New Zealand identity that finds ‘composure’ in the story of how Pākehā became ‘native’ New Zealanders.4 For Māori, these issues are keenly felt, because while New Zealand history has always been about us, it has predominantly been articulated on the colonizers’ terms. In the ‘discursive constructions’ that are New Zealand histories, the indigenous have regularly been culturally appropriated, dislocated and misrepresented.5 Even when Māori have turned their back on the writing of New Zealand history it has been, and will still be, a history of being or becoming ‘native’. Yes, New Zealand history is Māori history – so why does it feel like the story of Pākehā settlers?

year: 2015