Impact testing of pristine and repaired carbon fibre reinforced polymer composite materials for aircraft structures

Aircraft technologies and materials have been developing and improving drastically over the last hundred years. Over the last three decades, an interest in the use of composites for the external structures has become prominent. For this to be possible, thorough research on the performance of composite materials, specifically the impact performance, is required. Previous research of impact testing for pristine carbon-reinforced epoxy composites describes matrix cracks, fibre fracture and delamination as the failure modes that require monitoring. An area of concern with the use of composites for aerostructures is their ability to be repaired and retain a suitable level of performance. Currently, since there are limitations in non-destructive testing (NDT) methods for adhesive bonding, adhesively joined or repaired composite materials are restricted to being used for secondary structures within the aircraft, unless another joining method – such as mechanical fasteners – are also implemented. Rigorous research and testing are required in this area because the current technique for metals, of bolting an undamaged piece of material over the damaged area, is not effective for composites as it introduces detrimental damage. There are two main repair techniques for composite materials: scarf and patch repair. Investigating the potential of the latter to restore the impact properties of carbon fibre reinforced polymer (CFRP) composite panels contributes to a large section of the research in this thesis. Two different types of lay-up (quasi-isotropic and cross-ply) were tested, with repair variables such as the patch diameter, patch thickness, inclusion of a plug and distance of the impact site from the centre of the patch being adjusted to see how each affects the overall performance of the repair. It was seen that the patch diameter has little to no effect on the repair performance, with both 55 and 65 mm patches giving similar load traces. The patch thickness and inclusion of a plug had a more significant effect on the impact properties of the repairs, with the two best performing repair configurations being a thick patch and a thin patch reinforced with a plug. The location of the impact site also greatly affected the performance of the panel, with impacting on the patch but not centrally giving the largest damage area of all the configurations tested. Two primary types of impact will be considered in this thesis: hard and soft. Hard impacts are defined as having limited deformation of the impactor upon impact, examples of which include metal debris hitting the aircraft. Soft impacts have a significant amount of deformation of the impactor and include hail stones or bird strikes. Considering the transition from a hard to a soft impact and the effect this has on the failure modes seen in the CFRP is investigated as part of the research in this thesis. To consider this, a rounded stainless-steel impactor, flat ended stainless-steel impactor and a flat ended stainless-steel impactor with different thicknesses of neoprene adhered to the end were used to impact pristine quasi-isotropic material. The results suggested that, although a lower damage initiation value was observed for the samples impacted with the round-nosed impactor in comparison, the samples impacted with the flat-ended impactor had a larger damage area once damage did initiate. The addition of rubber reduced the peak load and increased the displacement of the samples. It was also seen that the damage area reduced slightly as the thickness of rubber increased. Another area of interest is accurately predicting the impact performance of pristine panels under both hard and soft impact loading conditions through the use of numerical modelling. This allows for various scenarios and the transition between the two types of impact to be considered without the cost and time of experimental work. In this thesis, a model has been developed and compared with the experimental results for the hard and soft impact research to investigate the potential for it to be used to determine suitable scenarios to test experimentally. The numerical analysis results reflected the overall trends observed experimentally when increasing impact energy for round-nosed impacts and also when increasing the softness of the impact, with excellent agreement between the simulation and experimental testing for the damage area produced by a 7.5 J round-nosed impact. This demonstrates the potential to use a model similar to the one in this thesis to predict the performance of CFRP panels under impact loading conditions, but also highlights some drawbacks and a need for further development and refinement to improve the accuracy.Open Acces

King Mountain Neighborhood Urban Village environmental impact assessment

Two-hundred-eighty-six acres of land were recently incorporated into Bellingham\u27s urban growth boundary, allowing the land to be developed at higher densities. Alliance Properties has proposed development of a high-density, mixed-use urban village on 135 acres of undeveloped land on King Mountain near James Street. An extension of James Street will continue up to Van Wyck Road. Sixty-eight acres will be used for residential land, 46 acres for open spaces and parks, and 21 acres for roads. In the proposed development area, an urban village center will be constructed. This center will contain residential and commercial uses, from cafes and stores to apartments, townhouses and single family residences

Posttraumatic stress reactions following burglary: The role of coping and personality

This study aimed to investigate the extent of posttraumatic stress reactions and psychiatric comorbidity following burglary and whether personality traits and coping strategies would relate to outcomes. One hundred twenty-five victims of burglary participated in the study. In addition to reporting information on their personal experiences of burglary, victims completed the Impact of Event Scale, the General Health Questionnaire-28 (GHQ-28), the Eysenck Personality Questionnaire-R Short Scale, and the Ways of Coping Checklist. As a group, victims of burglary reported posttraumatic stress symptoms at a medium level of severity, while 41% met the cutoff for the high level of severity. Thirty-eight percent scored above the cutoff for the GHQ-28. Controlling for the characteristics of burglary, neuroticism related only to psychiatric comorbidity. Psychoticism buffered against the effects of both posttraumatic stress and psychiatric outcomes. Low scores on extraversion related to posttraumatic stress. Emotion-focused coping strategies related to both outcomes, while problem-focused coping buffered against the effect of psychiatric comorbid symptoms. No mediational relationships were found between personality traits, coping strategies, and outcomes. Victims of burglary can experience posttraumatic stress reactions associated with burglary and a range of other psychiatric symptoms. Personality traits of psychoticism, extraversion, and neuroticism influence outcomes in unique ways. Emotion-focused coping is not seemingly helpful in coping with the effects of burglary. © 2014 American Psychological Association

Degradation of Artemisinin-Based Combination Therapies Under Tropical Conditions.

Poor quality antimalarials, including falsified, substandard, and degraded drugs, are a serious health concern in malaria-endemic countries. Guidelines are lacking on how to distinguish between substandard and degraded drugs. "Forced degradation" in an oven was carried out on three common artemisinin-based combination therapy (ACT) brands to detect products of degradation using liquid chromatography mass spectrometry and help facilitate classification of degraded drugs. "Natural aging" of 2,880 tablets each of ACTs artemether/lumefantrine and artesunate/amodiaquine was undertaken to evaluate their long-term stability in tropical climates. Samples were aged in the presence and absence of light on-site in Ghana and in a stability chamber (London), removed at regular intervals, and analyzed to determine loss of the active pharmaceutical ingredients (APIs) over time and detect products of degradation. Loss of APIs in naturally aged tablets (both in Ghana and the pharmaceutical stability chamber) was 0-7% over 3 years (∼12 months beyond expiry) with low levels of degradation products detected. Using this developed methodology, it was found that a quarter of ACTs purchased in Enugu, Nigeria (concurrent study), that would have been classified as substandard, were in fact degraded. Presence of degradation products together with evidence of insufficient APIs can be used to classify drugs as degraded

Using an Alternative Method to Estimate Overcount for Census 2021.

Objectives The project aimed to test an alternative method to estimate the number of duplicate responses  in the 2021 England and Wales Census. The method utilises information from all census records instead of relying on samples. It requires less clerical review  than the original inverse sampling method used for overcount estimation. Approach We used the Splink implementation of Fellegi-Sunter to match the 2021 Census to itself. The resulting linked dataset was filtered to retain only the top scoring record pair for each unique census record, giving a final dataset of around 71.5 million record pairs. These pairs were divided by score into 13 homogeneous buckets. Random samples of 1000 pairs per bucket were clerically reviewed to determine whether each pair was a true duplicate or not. The clerical results were used to assign an estimated probability of being a duplicate to each bucket and hence to every census record within the bucket. Results A dashboard was created which contained percentages of duplicates by region and ‘overcount group’ for the original and alternative methods. This enabled us to view the data side by side and create visualisations to aid analysis. The alternative method had higher average duplicate percentages in overcount groups for communal establishments and was also higher for 9 out of 10 regions in the armed forces overcount group. We found that both the original and alternative methods of overcount estimation followed the same pattern in terms of minimum and maximum duplicate percentages except for those in communal establishments where minimum and maximums were both higher than the original method. Additionally, the minimum was marginally higher for the student and armed forces overcount groups for the alternative method. Conclusion On initial comparison, estimated rates of duplication resulting from the different methods are comparable. We plan to conduct further analysis on the similarities and differences of the two methods, and research whether the new method could be applied to estimate the duplication rate in other large datasets including administrative data

Exploring the role of the microbiota member Bifidobacterium in modulating immune-linked diseases

The gut-associated microbiota is essential for multiple physiological processes, including immune development. Acquisition of our initial pioneer microbial communities, including the dominant early life genus Bifidobacterium, occurs at a critical period of immune maturation and programming. Bifidobacteria are resident microbiota members throughout our lifetime and have been shown to modulate specific immune cells and pathways. Notably, reductions in this genus have been associated with several diseases, including inflammatory bowel disease. In this review, we provide an overview of bifidobacteria profiles throughout life and how different strains of bifidobacteria have been implicated in immune modulation in disease states. The focus will be examining preclinical models and outcomes from clinical trials on immune-linked chronic conditions. Finally, we highlight some of the important unresolved questions in relation to Bifidobacterium-mediated immune modulation and implications for future directions, trials, and development of new therapies

‘Lines of Flight or Tethered Wings?’ A Deleuzian Analysis of Women-specific Adventure Skills Courses in the United Kingdom

In this paper we examine women-specific adventure sport skills training courses in the UK utilising a feminist new materialist approach. Drawing on Deleuze & Guattari’s (1987) concepts of ‘assemblage’. ‘lines of territorialisation’ and ‘lines of flight’, we apply a new lens to ask: what type(s) of material-discursive assemblages are produced through human and non-human, discursive and non-discursive intra-actions on women-specific adventure sport skills courses? To what extent do these courses enable participants to engage with an alternative praxis and ethics and to think, feel, practice, and become otherwise? Our Deleuzian reading showed that the affective capacity of these courses is currently limited by dominant understandings of these courses as bridges to the real outdoors and as primarily designed for women who lack the confidence to participate in mixed-gender environments. However, these courses also enabled productive lines of flight and alternative understandings and practices related to the self, the body, others, material objects, learning, movement, and physical activity to emerge. These were both characterised and supported by less instrumental and hierarchical flows of relations and an openness to not knowing

Pet ownership and grief - Exploring how pet ownership effects owners' mental wellbeing during times of grief, a qualitative pilot study

Animal-assisted interventions (AAIs) have exhibited encouraging outcomes in enhancing human mental health. However, research has investigated the potential benefits of untrained pets for human mental wellbeing, as training animals for AAI can be costly and time-consuming. However, despite times of grief representing a significant risk factor for poor mental wellbeing, to date few studies have explored how pets may protect owner mental wellbeing during this period. This qualitative study explored how pet ownership impacts owner's mental wellbeing during times of grief, and through what mechanisms. This study used semi-structured interviews to interview pet owners who had lost a loved one (human) in the last 2 years. Twelve participants took part in the interviews which were analysed with thematic analysis. The analysis determined three key themes: hedonic wellbeing, feeling connected, and emotion regulation. The mechanisms that lead to owners' mental wellbeing during times of grief were varied, including things like cuddling and walking pets, as well as just being in their presence. The key benefits owners derived from these activities and interactions are discussed. The findings of this study highlights how different owner-pet activities and interactions bring differing benefits. While further studies are necessary, these preliminary findings can help inform current guidelines on pet ownership, and further understanding how these key relationships in times of grief. Future research should explore further the mechanisms related to pet ownership and grief

The role of salt bridges, charge density, and subunit flexibility in determining disassembly routes of protein complexes

Mass spectrometry can be used to characterize multiprotein complexes, defining their subunit stoichiometry and composition following solution disruption and collision-induced dissociation (CID). While CID of protein complexes in the gas phase typically results in the dissociation of unfolded subunits, a second atypical route is possible wherein compact subunits or subcomplexes are ejected without unfolding. Because tertiary structure and subunit interactions may be retained, this is the preferred route for structural investigations. How can we influence which pathway is adopted? By studying properties of a series of homomeric and heteromeric protein complexes and varying their overall charge in solution, we found that low subunit flexibility, higher charge densities, fewer salt bridges, and smaller interfaces are likely to be involved in promoting dissociation routes without unfolding. Manipulating the charge on a protein complex therefore enables us to direct dissociation through structurally informative pathways that mimic those followed in solution