title: Non-destructive evaluation of additively manufactured materials: developing a coupled acoustic emission and thermoelastic stress analysis approach

authors: Jouan, Denis

abstract: A method combining two non-destructive evaluations techniques, acoustic emission and thermoelastic stress analysis, is proposed to monitor cyclically loaded monolithic and additive manufactured metallic samples for crack growth. Current literature was used to investigate additive manufacturing processes and their current quality control methods. A review of acoustic emission and thermoelastic stress analysis theory and recent applications is also provided. It was found that there was currently a gap in monitoring methods for additive manufactured parts under fatigue loading for crack growth due to internal defects. Acoustic emission and thermoelastic stress analysis have never been combined to monitor crack growth in monolithic or additive manufactured metals in such a way and would be ideal methods for crack growth monitoring under cyclic loading due to their inherent benefits. Thermoelastic stress analysis is a full-field non-contact non-destructive evaluation technique which can monitor surface stress fields in materials subjected to cyclic loading. Acoustic emission is ideal for monitoring fatigue damage due to its continuous monitoring capabilities of energy released by crack growth. The proposed method consisted of acoustic emission capturing continuously and saving any waveforms exceeding a set threshold while the thermoelastic stress analysis captured data at regular intervals. Acoustic emission energy was extracted from captured waveforms to provide crack initiation detection as well as a measure of crack severity. Thermoelastic stress analysis provided a crack tip location and enabled crack tip tracking as well as crack growth rate monitoring to complement the acoustic emission energy findings. Acoustic emission could not locate the crack because it only used a single piezoelectric sensor but could detect crack growth anywhere on the sample while thermoelastic stress analysis could give the crack location only if the crack was near the surface or within the field of observation. The method successfully detected cracks and tracked crack growth in monolithic aluminium samples, additive manufactured aluminium and additive manufactured titanium alloy samples under fatigue loading conditions. This method involves little modification to the part being observed, the surface must be painted with a thin coat of matt black paint for thermoelastic stress analysis, and a sensor must be attached to the part for acoustic emission. Acoustic emission energy detected crack growth before thermoelastic stress analysis in most tests however this was due to the experimental method, acoustic emission captures continuously while thermoelastic stress analysis is at regular time intervals. Issues with experimental method came to light in early tests but were addressed in the final tests using additive manufactured titanium samples. Future work includes testing additive manufactured samples with built-in subsurface defects and developing a chip-based system in order to make a smaller and cheaper monitoring system.

text: Non-destructive evaluation of additively manufactured materials: developing a coupled acoustic emission and thermoelastic stress analysis approach A method combining two non-destructive evaluations techniques, acoustic emission and thermoelastic stress analysis, is proposed to monitor cyclically loaded monolithic and additive manufactured metallic samples for crack growth. Current literature was used to investigate additive manufacturing processes and their current quality control methods. A review of acoustic emission and thermoelastic stress analysis theory and recent applications is also provided. It was found that there was currently a gap in monitoring methods for additive manufactured parts under fatigue loading for crack growth due to internal defects. Acoustic emission and thermoelastic stress analysis have never been combined to monitor crack growth in monolithic or additive manufactured metals in such a way and would be ideal methods for crack growth monitoring under cyclic loading due to their inherent benefits. Thermoelastic stress analysis is a full-field non-contact non-destructive evaluation technique which can monitor surface stress fields in materials subjected to cyclic loading. Acoustic emission is ideal for monitoring fatigue damage due to its continuous monitoring capabilities of energy released by crack growth. The proposed method consisted of acoustic emission capturing continuously and saving any waveforms exceeding a set threshold while the thermoelastic stress analysis captured data at regular intervals. Acoustic emission energy was extracted from captured waveforms to provide crack initiation detection as well as a measure of crack severity. Thermoelastic stress analysis provided a crack tip location and enabled crack tip tracking as well as crack growth rate monitoring to complement the acoustic emission energy findings. Acoustic emission could not locate the crack because it only used a single piezoelectric sensor but could detect crack growth anywhere on the sample while thermoelastic stress analysis could give the crack location only if the crack was near the surface or within the field of observation. The method successfully detected cracks and tracked crack growth in monolithic aluminium samples, additive manufactured aluminium and additive manufactured titanium alloy samples under fatigue loading conditions. This method involves little modification to the part being observed, the surface must be painted with a thin coat of matt black paint for thermoelastic stress analysis, and a sensor must be attached to the part for acoustic emission. Acoustic emission energy detected crack growth before thermoelastic stress analysis in most tests however this was due to the experimental method, acoustic emission captures continuously while thermoelastic stress analysis is at regular time intervals. Issues with experimental method came to light in early tests but were addressed in the final tests using additive manufactured titanium samples. Future work includes testing additive manufactured samples with built-in subsurface defects and developing a chip-based system in order to make a smaller and cheaper monitoring system.

year: 2022

title: Unravelling Syria's Entho-Sectarian Politics

authors: Townshend, Estelle Jane

subjects: Sectarian international relations Middle East

abstract: Goaded by the regional repercussions of the Syrian crisis sectarian tensions are emerging as the key threat to Middle Eastern and Syrian stability.  Sectarianism has had a big impact on politics in Syria, it is implicated in the maintenance of authoritarianism, and sectarian dynamics are escalating the intensity of the uprising against the Assad regime.   Prior to the civil war communal bonds between regime members and minority sect insecurity were key to the survival of the regime.   Political power and control was maintained through fear and this was not just fear of the powerful security forces but also fear of sectarian conflict with the regime highlighting the risk of sectarian conflict, minority persecution and instability should the regime fall.  As a result many supported or tolerated the Assads out of fear of the alternative. 
This thesis aims to analyse the extent and the manner in which political players in Syria have used religious narratives and manipulated sectarian identities in their pursuit of power. It concludes that sectarian tactics have been intensified within the Syrian uprising by both the regime and within the opposition.   Religious narratives for mobilising support have become widespread and an emphasis on dangers from the ‘other’ is prevalent.  Given Middle Eastern history of intolerance towards other religious and ethnic groups this emphasis on confessional narratives is intensifying the dangers of sectarian violence within the civil war and creating rifts that will be hard to heal.   
The use of religious narratives for political goals is a feature of the religious and political landscape and this is analysed through the lens of Ethnic Conflict Theory.   With radical Islam heavily featuring narratives that emphasise opposition to other, an entitlement to dominate and an admiration of religious warrior characteristics alongside the cultural importance of nested communal groups, Islam has served as a readymade construct for mobilising sectarian groups against political foes.
However although many sectarian narratives refer heavily to history the current confessional tensions relate specifically to the present. With Middle Eastern autocratic regimes under threat due to the Arab Spring many groups perceive that political power is up for grabs and are finding it expedient – and religiously justifiable - to mobilise through the established channels of confessional loyalties and networks particularly along Sunni versus Shia lines.  Plus given the importance of religion to the region it is a clear front runner as justification for political and/or armed action.   
Advances in communications technology, specifically social media, and the breakdown of regime authority has allowed for voices to be heard from within an autocratic state that had otherwise been silenced, thus providing an unprecedented opportunity to analyse sectarian politics within a civil war.

text: Unravelling Syria's Entho-Sectarian Politics Goaded by the regional repercussions of the Syrian crisis sectarian tensions are emerging as the key threat to Middle Eastern and Syrian stability.  Sectarianism has had a big impact on politics in Syria, it is implicated in the maintenance of authoritarianism, and sectarian dynamics are escalating the intensity of the uprising against the Assad regime.   Prior to the civil war communal bonds between regime members and minority sect insecurity were key to the survival of the regime.   Political power and control was maintained through fear and this was not just fear of the powerful security forces but also fear of sectarian conflict with the regime highlighting the risk of sectarian conflict, minority persecution and instability should the regime fall.  As a result many supported or tolerated the Assads out of fear of the alternative. 
This thesis aims to analyse the extent and the manner in which political players in Syria have used religious narratives and manipulated sectarian identities in their pursuit of power. It concludes that sectarian tactics have been intensified within the Syrian uprising by both the regime and within the opposition.   Religious narratives for mobilising support have become widespread and an emphasis on dangers from the ‘other’ is prevalent.  Given Middle Eastern history of intolerance towards other religious and ethnic groups this emphasis on confessional narratives is intensifying the dangers of sectarian violence within the civil war and creating rifts that will be hard to heal.   
The use of religious narratives for political goals is a feature of the religious and political landscape and this is analysed through the lens of Ethnic Conflict Theory.   With radical Islam heavily featuring narratives that emphasise opposition to other, an entitlement to dominate and an admiration of religious warrior characteristics alongside the cultural importance of nested communal groups, Islam has served as a readymade construct for mobilising sectarian groups against political foes.
However although many sectarian narratives refer heavily to history the current confessional tensions relate specifically to the present. With Middle Eastern autocratic regimes under threat due to the Arab Spring many groups perceive that political power is up for grabs and are finding it expedient – and religiously justifiable - to mobilise through the established channels of confessional loyalties and networks particularly along Sunni versus Shia lines.  Plus given the importance of religion to the region it is a clear front runner as justification for political and/or armed action.   
Advances in communications technology, specifically social media, and the breakdown of regime authority has allowed for voices to be heard from within an autocratic state that had otherwise been silenced, thus providing an unprecedented opportunity to analyse sectarian politics within a civil war.

year: 2013

title: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre

authors: Tompson, Lisa

subjects: Community Safety

abstract: This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

text: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

year: 2025