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High pressure structure of lanthanum
Get PDFThe behaviour of the lanthanum (La) metal at high pressure is of great interest because it provides insight into the behaviour of f electrons in high density metals, and also because high-pressure lanthanum hydrides have some of the highest superconducting temperatures known. Understanding the high-pressure phases of La is then vital in identifying the hydrogen content of these super-hydrides. However, the structure of La above 70 GPa is uncertain and a number of different, but related, structural forms have been reported in the literature. We have collected new, high-quality diffraction data to 230 GPa (2.3 Mbars) using the sub-micron diameter x-ray beam now available at the PETRA-III synchrotron. Analysis of this new data using Rietveld and Le Bail analysis reveals that La transforms to a body-centred tetragonal structure above ~80 GPa, a structure long-known in neighbouring element Ce, and confirming
a previous unpublished experimental result from our group and a recent computational
prediction.Engineering and Physical Sciences Research Council (EPSRC)EPSRC Grant No. EP/R02927X/1Atomic Weapons Establishment (AWE)Defence and Security Doctoral Symposia 2024 (DSDS24
Climate change impacts on shoreline migration and community livelihood resilience: evidence from coastal Bangladesh
Get PDFThe livelihoods of coastal people are at risk as shoreline migration is accelerated by climate change. To safeguard these communities and maintain their economy, it is imperative to strengthen resilience via adaptive strategies. Therefore, this study aims to estimate the rates and impacts of physical shoreline migration over the past 9,000 years using geospatial analysis and focus on understanding the livelihood resilience of coastal at-risk communities using in-depth interviews with environmental experts. The dynamic system of the Ganga-Brahmaputra-Meghna is highly complex and causes continuous shoreline migration. Historical data and more recent satellite remote sensing imagery analysis identified that the shrinking of the delta system has resulted from the migration of the shorelines at the mouth of the river system. Since 5,000 BP, it has been expanding towards the Bay of Bengal – meaning land gains at the coast. Land gain provides an opportunity for the extension of coastal communities but also increases their vulnerability to natural hazards. Moreover, by 2050, the salinity isoline with a 5-ppt is expected to shift inland by ⁓8 km in the south-east (Bhola-Patuakhali) and ⁓24 km in the southwest (Khulna-Satkhira) region. The in-depth interviews reveal several adaptive practices to effectively deal with the situation, including community knowledge, stakeholder engagement, local-led adaptation, and most importantly, temporal migration. The findings also highlighted the urgent need for an adaptation plan for the sustainability and resilience of coastal communities, considering indigenous knowledge with local cultural orientation and incorporation of scientific standards.Frontiers in Sustainabilit
Digital Twin-Based Health Management for Complex Aircraft Systems: Case Studies and Applications
Get PDFDigital Twin technology, initially conceptualized during the NASA's Apollo program, has evolved into a transformative tool for system health management, particularly in aviation. By integrating high-fidelity simulations, real-time sensor data, and predictive analytics, DTs enable significant innovation in Prognostics and Health Management methods. This paper explores the application of DTs in health management for complex aircraft systems, focusing on two critical subsystems: Flight Control Electrical Actuators and Main Landing Gear. Leveraging MATLAB Simscape, modular DT frameworks were developed to simulate these systems under nominal, degraded, and fault conditions. The inclusion of fault injection models enables the generation of realistic datasets to support predictive maintenance, alleviating difficulties in data availability. Two case studies are presented to illustrate the potential of DT-based approaches to reduce downtime, optimizing performance, and enhancing system reliability. This paper provides a comparative analysis of existing DT tools, highlighting their capabilities and limitations in aerospace contexts. While platforms such as MATLAB Simulink and ANSYS Twin Builder offer robust modeling capabilities, operational tools like AVIATAR and IBM Maximo excel in fleet management and predictive analytics. This comparison highlights the need for tailored DT solutions that balance real-time capabilities, scalability, and configurability. This study contributes to the growing body of knowledge on DT technology, offering insights into its role in enhancing aviation safety, efficiency, and sustainability. It serves as a guide for applying DT-based health management, paving the way for broader adoption in next-generation aerospace systems.Innovate UKThe research on Main Landing Gear Force and Torque DT was funded by Innovate UK grant number 10040817, under the ATI/IUK. The project was part of the OLLGA (Optimised Life for Landing Gear Assemblies), with Safran Landing Systems UK Ltd as Industrial Lead.2025 IEEE Wireless Communications and Networking Conference (WCNC
Fast implicit direct-forcing immersed boundary method (FIDF-IBM)
Get PDFA fast implicit direct-forcing immersed boundary method (FIDF-IBM) is introduced for the simulation of incompressible flows over arbitrarily moving solid structures. This method leverages the operator splitting approach of the pressure implicit with splitting of operators (PISO) algorithm to decouple the pressure, velocity, and boundary force in the solution process. This maintains the no-slip/no-penetration (ns/np) boundary constraint and enforces the divergence-free condition in a segregated manner in the solid and fluid domains, respectively. The proposed scheme produces a modified pressure Poisson equation (PPE) that includes the boundary force already satisfying the ns/np boundary constraint, allowing the usage of fast iterative PPE solvers. The term “fast direct-forcing” is achieved by coupling Lagrangian weight methods that enhance the reciprocity of the IBM-related linear operators with the IBM implicit formulation. Additionally, an appropriate boundary force inheritance from previous time-steps further boosts the performance of the implicit DF-IBM algorithm. The method’s efficiency and capability are verified through different stationary and moving immersed boundary benchmark tests.This research was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) (Grant No. EP/T518104/1, Project Reference No. 2676291)Engineering Analysis with Boundary Element
Techno-economic assessment of pressure swing adsorption tail gas decarbonisation for blue hydrogen production
Get PDFSteam methane reforming (SMR) is a leading technology for hydrogen production. However, this technology is still carbon-intensive since, in current SMR units, the PSA tail gas containing H2, CO, and CH4 is burned at the reformer with air and exits the stack at a CO2 purity of less than 5%, which is not feasible to capture. In this paper, we aim to either harness the energy content of this gas to generate power in a solid oxide fuel cell (SOFC) or burn it via chemical looping combustion (CLC) or oxy-combustion process to produce off-gas with high CO2 purity ready to storage. Therefore, an industrial-scale PSA with 72,000 Nm3/h feed capacity was modelled to obtain the tail gas flow rate and composition. Then, CLC, SOFC, and oxy-combustion were modelled to use tail gas. Finally, a techno-economic analysis was conducted to calculate each technology's levelised cost of hydrogen (LCOH). It was observed that CO2 purity for CLC meets the criteria for storage (>95%) without further purification. On the other hand, from the economic point of view, all three technologies show a promising performance with an LCOH of 1.9 €/kg.Gas Science and Engineerin
Wear modeling and friction-induced noise: a review
Get PDFWear and friction-induced noise are pivotal tribological phenomena that significantly influence the longevity and efficiency of mechanical systems. This review synthesizes current research on wear modeling and friction-induced noise, exploring their mechanisms, influencing factors, and predictive challenges. Wear modeling encompasses a range of approaches, from traditional methods such as the Archard equation to more advanced numerical and machine learning techniques. These models address diverse mechanisms—adhesive, abrasive, and fatigue wear—which are shaped by material properties, surface roughness, and environmental conditions. Friction-induced noise, arising from stick-slip, sprag-slip, and mode-coupling, is influenced by surface states, damping, and operational parameters. Crucially, wear and noise are interlinked. Wear reshapes surfaces and dynamics, thereby modulating noise, while noise can serve as a diagnostic tool for wear progression. Yet, existing models often isolate these phenomena, neglecting their synergy and impeding accurate system-life predictions. This review highlights this gap and advocates for the development of integrated wear-noise models, harnessing multiscale simulations, advanced computation, and empirical validation. The development of such models has the potential to significantly enhance the accuracy of durability and acoustic performance predictions. They offer a holistic framework that captures the dynamic interplay between surface degradation and noise generation. This framework is essential for advancing non-invasive detection technologies in industries such as automotive, aerospace, and manufacturing. In these sectors, addressing these dual challenges is crucial for enhancing performance, safety, and efficiency.wearFrictio
A novel cryogenic storage solution for atmosphere-breathing electric propulsion systems
Get PDFRecent interest in missions to Very Low Earth Orbit (VLEO) has led to the
emergence of Atmosphere Breathing Electric Propulsion (ABEP). In theory this
technology could enable missions to VLEO that forego the need to launch with
propellant. This innovative concept could allow the full potential of low altitude
regimes to be exploited as propellant consumption no longer limits lifetime. The
most promising designs use a passive intake system that requires no moving parts
to operate. Natural phenomena caused by the flow conditions at orbital velocity
are exploited to provide an electric thruster with an adequate supply of gas.
However a previously identified shortfall in its capabilities is that no propellant is
stored during operation. This leaves the system at the mercy of the unpredictable
conditions witnessed in Earth’s atmosphere.
This thesis proposes a solution to this problem. If molecules ingested by a passive
intake can be cooled to cryogenic temperatures, they can be temporarily captured
so long as they are kept cold. This phenomenon has the potential to be exploited
as an in-orbit propellant storage system.
To investigate this concept, firstly a baseline mathematical model for an ABEP
system was constructed using current design methodologies. Secondly, this
system was adapted to incorporate the novel storage concept. The resulting
model was then compared to the baseline along common performance parameters
in order to assess its feasibility.
The results showed that during the collection of propellant the requirements on
flow conditions for adequate performance became more stringent. Nevertheless
a feasible operating region was found and a baseline system chosen. This design
point allowed for a propellant collection rate of between 0.43 mg/s and 0.74 mg/s.
At this rate of collection, calculations speculated a potential for >1000 m/s of
Δv over an 8 year mission could be gained. If realised, the potential mission
applications are vast and could not only complement the performance of ABEP
systems but open up novel mission concepts such as in-orbit refuelling.MSc in Astronautics and Space Engineerin
Wave interaction with multiple floating elastic plates with arbitrary constraints near a sloping beach
Get PDFThe problem of wave interaction with multiple elastic plates floating near a sloping beach is considered, particularly resembling the case of a floating solar farm near a coast. The linearized shallow water theory is adopted to describe the motion of fluid. The Kirchhoff–Love plate theory is used to model the elastic plates. A highly efficient domain decomposition approach is applied to derive the solution. Particularly, the eigenfunction expansions are employed to establish the velocity potential in free surface fluid domains, while the Green function method is used to construct the velocity potential of the fluid domain covered by floating elastic plates. This approach can significantly reduce the number of unknowns in the velocity potential, especially when a large number of plates are involved. Extensive results and discussions are provided for the wave run-up on the beach, maximum deflection, and principal strain on the elastic plates. In particular, based on a wide space approximated solution, the oscillatory behaviour of the wave run-up vs the incident wavenumber is analysed, along with the corresponding physical mechanisms. Furthermore, apart from the frequency-domain results, time-domain analyses are also conducted based on a Fourier transform approach. Two different types of incident impulses are considered to interact with floating elastic plates near a beach, namely a Gaussian wave packet and a storm-type incident wave.Royal Society, Innovate UK, National Natural Science Foundation of ChinaL.H. acknowledges grants received from Innovate UK (Nos. 10048187, 10079774, and 10081314), the Royal Society (IEC\NSFC\223253, RG R2 232462), and UK Department for Transport (TRIG2023—No. 30066).Physics of Fluid
Vortex formation downstream of an active vane vortex generator
Get PDFPrince, Simon - Associate SupervisorA blended wing body aircraft, with embedded engine intakes near the wing trailing
edge, requires aerodynamic optimisation under flight conditions to ensure
satisfactory aerodynamic performance. In such a configuration, the wing surface
upstream of the intake is a critical region within which active boundary layer flow
control could provide significant benefits. The static vortex generator has
additional drag under cruise conditions, but the active vortex generator not have
the same issue. If the active vortex generator (VG) were to be utilised, the
transient behavior of the flow downstream of the VG following its activation would
need to be understood.
The active vortex generator concept adopted in the current study is a thin flat
blade, inclined at a constant angle to the local flow direction, which can be
deployed from its ‘stowed’ (fully retracted position), allowing it to project into the
surface boundary layer and operate as a conventional blade vortex generator
once fully extended. This study investigates the transient characteristics of the
flow structure downstream of the blade during the deployment, using both up-
scaled experimental and numerical simulations. The results contribute data to the
development of an effective active flow control strategy, enhancing
understanding of the flow control techniques.
The experimental approach is designed to examine the fundamental
characteristics of the transient behaviour and is split into two work-phases. In
Phase I, the study is focused on exploring the feasibility of the experimental
approach to generate the vortex-forming transient. Phase II involves the use of a
scaled-up experiment for a detailed study of the transient flow structure at
Reynolds numbers in the range 1500 to 3500, based on local velocities in the
boundary layer and the heights of the blade.
In the Phase II experiment, a multi-hole pressure probe is used to record the
vortex formation and decay characteristics in a given downstream plane. The
data show that the vortex development has a nonlinear response to the blade
deflection during the blade deployment. This Phase II data is compared to both
RANS CFD steady-state simulations and analytical predictions using empirical
models under steady conditions. The supplementary study indicates that the
vortex-forming process is dependent on the transient nature of the VG blade
deployment and cannot be adequately represented by the steady analysis.
A key outcome of this study relates to the practical application of vortex
movement within the embedded boundary layer as a result of the VG blade
deflection. The transient vortex position profile between the stowed (no vortex)
and the deployed (steady-state or static vortex) location is very different from that
predicted by steady-state modeling. The transient vortex vertical motion causes
a smoother local circulation increase compared to the starting vortex, and the
nonlinear circulation variations remain independent of blade size effects.
Furthermore, the findings presented in this thesis offer insight into active flow
control. With continued study, the active blade vortex generator can increase the
aircraft's efficiency and performance.PhD in Aerospac
Will climate change affect growth and ochratoxin A production of putative biocontrol knockout strains of Aspergillus carbonarius?
Get PDFThe research explored the effects of abiotic factors associated with climate change (CC) on the growth and metabolite production of wild-type Aspergillus carbonarius ITEM 5010 and three knockout mutants: one knockout in the first gene of the ochratoxin A (OTA) biosynthesis pathway (ΔotaA) and two in the veA and laeA genes (the latter knockout generated in this work) encoding VELVET complex proteins, which regulate metabolism. Variables examined were temperature (30 °C vs 37 °C), water activity (0.98 vs 0.90), and CO₂ levels (400 ppm vs 1000 ppm). Growth, OTA production, and other metabolites were evaluated on grape-based medium. The results showed that abiotic factors significantly influenced fungal growth and mycotoxin production, with aw being the most critical parameter. At aw 0.90, no growth was observed. A temperature of 37 °C combined with 1000 ppm CO₂ resulted in higher OTA production, indicating a greater health risk in predicted CC scenarios. Mutants of global regulatory factors showed altered metabolite production, with elevated OTA levels at 37 °C. The ΔotaA knockout mutant consistently showed no OTA production, suggesting its viability as a biocontrol agent under CC conditions. However, while OTA increased, other secondary metabolites, such as pyranonigrin A and kojic acid, decreased with rising temperatures in all strains. The research highlights the influence of abiotic factors related to CC on A. carbonarius growth and metabolite production, underlining the threat of increased mycotoxin production. This reinforces the need for resilient biocontrol strategies. The ΔotaA mutant has been identified as a potential biocontrol agent, demonstrating resistance to future environmental stresses associated with CC.Ministerio de Ciencia, Innovación y Universidades; AGROALNEXT/2022/028This work was partially funded by projects PID2021-126005OBI00 (MICIU/AEI/10.13039/501100011033/FEDER, UE), AGROALNEXT/2022/028 (GVA, PRTR, MRR, NextGenerationEU), and PIE 202270I070 (CSIC).International Journal of Food Microbiolog