A comparison of the influence of using empirical or mathematically pre-defined wave energy spectra for tower base bending fatigue calculations

In the structural design of Floating Offshore Wind Turbines (FOWT), fatigue plays a critical role in determining the final design of the system. The fatigue loads are the result of combined aerodynamic and hydrodynamic forces acting on the elastic structure. The industry standard approach for assessing the fatigue loads involves grouping the environmental conditions into bins. These conditions include wind speed and direction, wave height, period and direction and the sea state spectral shape. In shallow seas with limited fetch the JONSWAP spectrum, or a JONSWAP-derived spectrum, is normally fitted to the site conditions and used, which also includes a peak enhancement factor (GAMMA) in a range defined by the significant wave height and peak period. However, this adjustment is sensitive to the parameter fitting process, while the vital Peak Enhancement Factor (gamma) parameter is commonly chosen as an arbitrary empirical value in the given range. In this paper, we examine how the calculation of bending fatigue of the tower base of the IEA 15MW open source turbine supported by the UMaine VolturnUS semi-submersible is influenced by either the use of empirical spectra (measured or simulated for the specific site) against pre-described site-fitted formulas for spectral shape, and the use of different spectra per hourly sea state against a single spectrum per data bin. The results indicate an influence of both the used spectral shape as well as the use of spectra for each sea state instead of a single spectrum per bin of data

The Posthuman

‘Posthuman’ is a multivalent and multidisciplinary term that references a complex, sometimes conflicted reconceptualization of the body and subjectivity resulting from developments in biology, technology and ecology, which highlight human animals as fundamentally relational and mutable. Biotechnology, genomic and transplantation sciences, microbiome research, climate science, cybernetics, and a host of other research areas have effectively cast doubt on the integrity and unity of ‘the human’ as a discrete material and conceptual entity. The posthuman and its attendant philosophies emerge out of this reconceptualization of the human as a malleable material entity interconnected and inter-related with a whole host of ‘others’, human, animal, environmental and technological. In cultural texts, posthuman bodies are frequently represented as those that have been enhanced and augmented, both functionally and aesthetically, by prostheses, implants or other assistive technologies. Posthuman bodies abound in contemporary literature and film, where the posthuman imaginary of the cyborg figure -- ‘a hybrid of machine and organism’, to use Haraway’s formulation1 -- enact two visions of posthuman discourse. First, a transgressive and liberatory vision, via thinkers such as Haraway, where entanglements with ‘others’ -- machines, animals, technologies etc. -- overthrow limiting categories of humanism and a ‘way out of the maze of dualisms’ that categorise Western thought’. And second, a transhuman vision, where entanglements with others -- primarily enhancement technologies -- produce post-human beings who have overcome the limiting realities of flesh-and-blood human bodies

Rearing zombie flies: Laboratory culturing of the behaviourally manipulating fungal pathogen Entomophthora muscae

Insect pathogenic fungi (IPF) and insects have ubiquitous interactions in nature. The extent of these interkingdom host-pathogen interactions are both complex and diverse. Some IPF, notably of the order Entomophthorales, manipulate their species-specific host before death. The fungus-induced altered insect behaviours are sequential and can accurately be repeatedly characterised temporally, making them a valuable model for understanding the molecular and chemical underpinnings of behaviour and host-pathogen co-evolutionary biology. Here, we present methods for the isolation and laboratory culturing of the emerging behaviourally manipulating model IPF Entomophthora muscae for experimentation.•E. muscae isolation and culturing in vitro.•Establishing and maintaining an E. muscae culture in vivo in houseflies (Musca domestica).•Controlled E. muscae infections for virulence experiments and quantification of conidia discharge per cadaver

The circular economy: A transformative service perspective

The rising awareness of climate challenges and resource constraints has strengthened interest in the circular economy (CE), characterized as an economic system aimed to minimize the depletion of the world’s natural resources through processes of value retention and value regeneration. Because CE research originated in the engineering field, studies to date have mostly focused on technical and management-related topics. However, due to increasing demands from customers, investors, governmental institutions, and regulatory bodies, companies are increasingly considering how to effectively implement the CE. Despite its increasing importance, the CE is yet an uncharted area of transformative service research (TSR), and little is known about how the CE can support change for greater well-being among individuals and collectives. To fill this research gap, we integrate notions of the CE with TSR and research on value co-creation. The purpose of this paper is to expand research on CE and services by taking a TSR perspective to delineate how value retention and regeneration processes for different levels and spheres in services can effect change for greater individual and collective well-being

2010 Survey of Technology Enhanced Learning for higher education in the UK

The Academic Support Group has carried out regular surveys on the use of technology enhanced learning in the higher education sector. In addition to reviewing the technology in use, the survey looks at the drivers behind the adoption of technology enhanced learning in institutions. The results of the 2010 survey, the fifth in the series, have now been published; results from previous surveys are also available

Ensuring equitable access, engagement and ability of socially and ethnically diverse participants to benefit from health promotion programmes: a qualitative study with parent carers of disabled children

Background: Equity is fundamental to health promotion programmes. However, unintentional or unseen barriers may exist for some underserved groups. We aimed to identify how to ensure equitable access and engagement for diverse parent carers of disabled children to benefit from health promotion programmes. Methods: We purposively sampled parent carers with potentially intersecting characteristics including those who self-identified as from ethnic groups, whose children were educated other than at school, with sensory impairments, or neurodiversity, and fathers. Participants were recruited through local and national organisations and parent carer networks. Data collection involved semi-structured individual interviews, which were transcribed verbatim and analysed thematically and iteratively alongside data collection. Core researchers performed early analysis independently, followed by research team and advisory group cross-validation. Results: Thirty-six parent carers with intersecting characteristics across the sampled backgrounds participated. We identified various perceived barriers around finding out about, attending and engaging with health programmes. We organised the findings into five themes focused on concepts capturing challenges and potential solutions to contextual barriers to access and participation in health programmes. (i) Reach—judiciously using targeted and universal strategies to ensure equitable distribution; (ii) Credibility—demonstrating trustworthiness of those advertising and/or delivering the programme; (iii) Opportunity—ensuring that the programme is seen as fulfilling a relevant need; (iv) Reservations—addressing barriers of readiness to participate; and (v) Optimisation—tailoring to improve the inclusivity of the programme delivery. Conclusion: We identified modifiable factors that impede members of some social groups from engaging with, and benefiting from, health promotion programmes, and potential solutions. We advocate a multifaceted approach is required from outreach to delivery, tailored to be mindful of extant diverse needs of parent carers in underserved communities. We catalogue key considerations to inform implementation strategies to optimise equity in health programmes for parent carers. The implications are likely transferable to other interventions and contexts

Glucocorticoid effects on the brain: from adaptive developmental plasticity to allostatic overload

Exposure to stress during early life may alter the developmental trajectory of an animal by a mechanism known as adaptive plasticity. For example, to enhance reproductive success in an adverse environment, it is known that animals accelerate their growth during development. However, these short-term fitness benefits are often associated with reduced longevity, a phenomenon known as the growth rate-lifespan trade-off. In humans, early life stress exposure compromises health later in life and increases disease susceptibility. Glucocorticoids (GCs) are major stress hormones implicated in these processes. This Review discusses the evidence for GC-mediated adaptive plasticity in development, leading to allostatic overload in later life. We focus on GC-induced effects on brain structure and function, including neurogenesis; highlight the need for longitudinal studies; and discuss approaches to identify molecular mechanisms mediating GC-induced alteration of the brain developmental trajectory leading to adult dysfunctions. Further understanding of how stress and GC exposure can alter developmental trajectories at the molecular and cellular level is of critical importance to reduce the burden of mental and physical ill health across the life course

Effects of wind turbine dimensions on the collision risk of raptors: A simulation approach based on flight height distributions

Wind energy development is a key component of climate change mitigation. However, birds collide with wind turbines, and this additional mortality may negatively impact populations. Collision risk could be reduced by informed selection of turbine dimensions, but the effects of turbine dimensions are still unknown for many species. As analyses of mortality data have several limitations, we applied a simulation approach based on flight height distributions of six European raptor species. To obtain accurate flight height data, we used high-frequency GPS tracking (GPS tags deployed on 275 individuals). The effects of ground clearance and rotor diameter of wind turbines on collision risk were studied using the Band collision risk model. Five species had a unimodal flight height distribution, with a mode below 25 m above ground level, while Short-toed Eagle showed a more uniform distribution with a weak mode between 120 and 260 m. The proportion of positions within 32–200 m ranged from 11 % in Marsh Harrier to 54 % in Red Kite. With increasing ground clearance (from 20 to 100 m), collision risk decreased in the species with low mode (−56 to −66 %), but increased in Short-toed Eagle (+38 %). With increasing rotor diameter (from 50 to 160 m) at fixed ground clearance, the collision risk per turbine increased in all species (+151 to +558 %), while the collision risk per MW decreased in the species with low mode (−50 % to −57 %). These results underpin that wind turbine dimensions can have substantial effects on the collision risk of raptors. As the effect varied between species, wind energy planning should consider the composition of the local bird community to optimise wind turbine dimensions. For species with a low mode of flight height, the collision risk for a given total power capacity could be reduced by increasing ground clearance, and using fewer turbines with larger diameter

Building Armour From Water: Understanding Calcification Physiology to Optimise Conditions for Indoor King Prawn Aquaculture

King prawn (Penaeus vannamei) production is one of the most valuable and fastest growing sectors in aquaculture. The industry is expanding globally, with a major shift toward indoor closed-system production where culture conditions can be carefully controlled and optimised to improve productivity, health, welfare, and quality of the product. The crustacean exoskeleton is a vital adaptation which provides mechanical support and physical protection from predation and diseases, therefore maintaining a healthy exoskeleton is important for successful culture. To grow this exoskeleton must be shed and replaced, through a process known as ecdysis. Immediately after ecdysis, the new exoskeleton must be calcified to complete the hardening process by taking up calcium and bicarbonate ions from the external water via the gills. The aims of this thesis were four-fold. Chapter Two aims to provide a comprehensive assessment of the impacts of light on aquaculture species and to identify a model system to investigate moulting in Penaeus vannamei using light manipulation. Chapter Three and Four aimed to identify the relationship between alkalinity and the net base uptake in the first 24 h post-moult and to investigate the subsequent effect of this relationship on exoskeleton composition. Significant knowledge gaps are identified for light impacts on aquaculture species, especially non-fish taxa. P. vannamei prefers moulting in the dark phase and moulting events can be constrained by reducing the dark period, generating an ideal model for investigating post-moult calcification in this species. This thesis revealed a Michaelis-Menten style saturation kinetics relationship between titratable alkalinity in the water and base uptake after moulting. It is postulated that this relationship explains why P. vannamei exposed acutely to low alkalinities post-moult have thinner, less-mineralised exoskeletons. This thesis recommends total alkalinity conditions of king prawns remain above >1,800 µmol L-1 to ensure bicarbonate uptake is not perturbed and therefore calcification is not affected. Alkalinity is a largely overlooked parameter in the industry and so this thesis highlights it’s importance for healthy king prawn husbandry

Control Methods for Launch and Recovery at Sea using Overhead Cranes

Launch and recovery (L&R) of a small vessel, from a large mothership, at high sea states is difficult and is usually avoided for safety reasons. This thesis deals with the study of the L&R mechanism using a crane onboard the ship. A novel feedback control system automating the recovery process of a small vessel at high sea states has been developed for the first time. An Euler-Lagrange approach is used to develop a two-dimensional dynamic model to determine the behaviour of the mothership-crane-small vessel system under different sea conditions. This model forms the basis for the design of a second-order sliding mode controller (SMC), which is used to change the length of the cable during the recovery process and ensures that a pre-defined profile is followed. At low sea states, this controller works robustly with safe recovery of the small vessel. However, at high sea states it is not sufficient in preventing collisions between the small vessel and the hull of the mothership. To provide more degrees of freedom, the crane has been modified to enable the movement of the suspension point. An Integral Sliding Mode Control (ISMC) approach is employed to adjust the crane’s boom such that the separation distance between the small vessel and the hull of the mothership are maintained at a safe level. This model is upgraded by the development of a three-dimensional mothership-crane-small vessel representation which allows the implementation of the previously designed controllers with only minor adjustments. As only two control actions are applied, one swing angle remains unconstrained resulting in large pendulations. This problem is tackled with the use of tethering lines to connect the mothership to the small vessel resulting in a damping effect. The recommended approach for a safe L&R process made here consists of the use of an adjustable boom crane with tethering lines. These physical tools, combined with the robust control algorithm will help enable the safe and successful L&R of the small vessel even in rough sea states