Fractal space frames and metamaterials for high mechanical efficiency

A solid slender beam of length $L$, made from a material of Young's modulus $Y$ and subject to a gentle compressive force $F$, requires a volume of material proportional to $L^{3}f^{1/2}$ [where $f\equiv F/(YL^{2})\ll 1$] in order to be stable against Euler buckling. By constructing a hierarchical space frame, we are able to systematically change the scaling of required material with $f$ so that it is proportional to $L^{3}f^{(G+1)/(G+2)}$, through changing the number of hierarchical levels $G$ present in the structure. Based on simple choices for the geometry of the space frames, we provide expressions specifying in detail the optimal structures (in this class) for different values of the loading parameter $f$. These structures may then be used to create effective materials which are elastically isotropic and have the combination of low density and high crush strength. Such a material could be used to make light-weight components of arbitrary shape.Comment: 6 pages, 4 figure

Exploring the relationship between civic engagement, early life, and wellbeing: a mixed methods study with a diverse sample of university students

The level of civic engagement within a society is said to be a clear reflection of the health of that society’s democracy (Barrett and Zani, 2015). Despite the growing global interest in civic engagement, especially in the context of higher education, UK-based empirical research is lacking, and applications of life history perspectives to the growing civic engagement phenomenon are especially sparse. The concept of civic engagement carries definitional ambiguity, is subjective, and does not hold a universal understanding. For the purpose of this thesis, definitions of civic engagement, wellbeing and early life can be located in the ‘definitions table’ (page 8) and are explored throughout. It has been found in the past that disadvantaged and ostracized groups are less likely to part-take in civic engagement than affluent groups (Beetham, 1994). All primary data were collected in East London, a culturally diverse and disadvantaged borough. Data were collected from a multifarious sample of students from international educational backgrounds at a widening participation university. No similar research was found in this context. As a result of this gap in the literature, the aim of this study was to explore the relationship between civic engagement, early life, and wellbeing among this underrepresented population. Three separate and unique empirical research studies were designed and conducted, including: a series of focus groups; a 3-part quantitative survey; and a series of in-depth life history interviews. Interview participants were sampled based on their survey responses. All three elements of research were influenced by the vast, multi-disciplinary literature landscape. This thesis includes a unique adaptation of a collaborative life calendar method for qualitative interviews to collect civic engagement data. Findings demonstrated a relationship between civic engagement, early life, and wellbeing. Impacts of socioeconomics and childhood adversities on civic engagement and wellbeing outcomes were highlighted. The survey component offered a plethora of data and findings, and these were explored further within the interviews. Findings demonstrated students to be civically engaged - although further echoed the aforementioned definitional ambiguity and underlined the ongoing challenges in universally measuring civic engagement. The survey demonstrates factors such as family stability and positive family relationships in early life may predict higher levels of civic engagement, wellbeing, and self-esteem. The qualitative elements explored the complex concept of civic engagement at depth, and the recognition that bringing together a diversity of voices and ideas that can better reflect and shape society is key. Motivations behind civic engagement were at times a pursuit of protecting others, or of personal development and wellbeing. Overall, the data demonstrates the relationship between early life, civic engagement, and wellbeing is a fluid, reciprocal and inter-linked relationship, where civic engagement may play a mediating factor between early life experiences and health and wellbeing. Within this thesis, the predetermined notion of what it means to be civically engaged was challenged and broadened to include hidden, daily, informal, potentially unmeasurable yet valuable acts of engagement in the civil society. Future research in the area may seek to capture these daily civic behaviors. Life histories are vital for better understanding civic engagement, and civic engagement has a strong relationship with wellbeing. Further studies are needed to better understand the inequalities of civic engagement within marginalised groups in the UK, and how these are associated with life trajectories. This thesis demonstrates the need for policy makers to better understand and respond to the role that socioeconomics and early life may play in generating civically engaged citizens and could help to improve uptake of political engagement by supporting educational initiatives that are able to collaboratively reach underrepresented groups, build trust, and ensure more voices are heard across all categories of civic engagement

High-frequency data observations from space shuttle main engine low pressure fuel turbopump discharge duct flex joint tripod failure investigation

Observations made by Marshall Space Flight Center (MSFC) engineers during their participation in the Space Shuttle Main Engine (SSME) low pressure fuel turbopump discharge duct flex joint tripod failure investigation are summarized. New signal processing techniques used by the Component Assessment Branch and the Induced Environments Branch during the failure investigation are described in detail. Moreover, nonlinear correlations between frequently encountered anomalous frequencies found in SSME dynamic data are discussed. A recommendation is made to continue low pressure fuel (LPF) duct testing through laboratory flow simulations and MSFC-managed technology test bed SSME testing

Characterization of MMIC devices for active array antennas

Certain aspects of monolithic microwave integrated circuit (MMIC) interconnectivity were investigated. Considerations that lead to preserving the inherently reproducible characteristics of the MMIC are proposed. It is shown that at radio frequencies (RF) greater than 20 GHz, the transition from the MMIC device to other transmission media must be an accurate RF match. It is proposed that the RF match is sufficiently critical to include the transition as part of the delivered MMIC package. The model to analyze several transitions is presented. This model consists of a succession of abrupt discontinuities in printed circuit transmission lines. The analysis of these discontinuities is achieved by the Spectral Galerkin technique, to establish the modes and mode matching, to generate the generalized S parameters of the individual discontinuities. Preliminary results achieved with this method are presented. It is concluded that special effects should be coordinated by the active array antenna industry toward standardization of MMIC packaging and characterization

Groundwater dependence and drought within the southern African development community

A groundwater situation analysis of the SADC region has been undertaken as part of the World Bank GEF Programme as a basis for ensuring equitable use of groundwater resources, particularly during periods of drought, both for human needs and for sustaining ecosystems. Much of the groundwater in the region occurs in weathered crystalline rocks suitable for dispersed supply to rural communities, although there are several aquifers capable of sustaining urban demand that contribute to the supply of several major cities and towns. A number of SADC Member States, such as Botswana, Namibia and South Africa, are very dependent on groundwater, whereas the Democratic Republic of Congo is least dependent. Groundwater dependence and groundwater demand, together providing an indication of drought vulnerability, have been assessed from the availability and coverage of groundwater data, but it is very apparent that reliable and comprehensive groundwater data are major deficiencies throughout the SADC region. Few attempts have thus been made to calculate renewable groundwater resource volumes or develop optimum use of groundwater, despite the fact that susceptibility of many Member States to drought requires them to consider mitigation strategies to lessen the hardships imposed largely on their rural population. Such strategy requires long-term intervention and not short-term emergency responses, a process that is directly related to availability of comprehensive groundwater datasets. Considerable effort in groundwater assessment and monitoring and the accumulation, evaluation and dissemination of essential datasets will thus be required to maintain population livelihoods in future years when water supply is projected to be in deficit in over half of the SADC Member States

European Youth Cybercrime, Online Harm and Online Risk Taking: 2022 Research Report

Researching cybercriminality to design new methods to prevent, investigate and mitigate cybercriminal behaviour. This is one of the largest studies to date exploring youth cybercriminality. The survey is informed by 5 key disciplines: cyberpsychology, criminology, psychology, neuroscience, and digital anthropology Results confirm that cybercrime and cyberdeviance is prevalent-survey finds that two thirds (69%) of European youth self-report to have committed at least one form of cybercrime or online harm or risk taking, and just under half 47.76% (N=3808) report to have engaged in criminal behaviour online, from summer of 2020 to the summer of 2021 Survey finds that males are more likely (74%) than females (65%) to self-report having been involved in at least one form of cybercrime or online harm or risk taking in the last year and results confirm that the majority of cybercrime and cyberdeviant behaviours are gendered. Survey analysis demonstrates that cybercriminal and online harm or risk taking behaviours form a cluster of 11 behaviours that are highly interrelated (CcCd-Cluster) and that cybercrime and online harm or risk taking behaviours represent a spectrum (CcCd-Spectrum) A significant shift from a siloed, categorical approach is needed in terms of how cybercrimes are conceptualised, investigated, and legislated