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Attention mechanism enhanced spatiotemporal-based deep learning approach for classifying barely visible impact damages in CFRP materials
Get PDFMost existing machine learning approaches for analysing thermograms mainly focus on either thermal images or pixel-wise temporal profiles of specimens. To fully leverage useful information in thermograms, this article presents a novel spatiotemporal-based deep learning model incorporating an attention mechanism. Using captured thermal image sequences, the model aims to better characterise barely visible impact damages (BVID) in composite materials caused by different impact energy levels. This model establishes the relationship between patterns of BVID in thermography and their corresponding impact energy levels by learning from spatial and temporal information simultaneously. Validation of the model using 100 composite specimens subjected to five different low-velocity impact forces demonstrates its superior performance with a classification accuracy of over 95%. The proposed approach can contribute to Structural Health Monitoring (SHM) community by enabling cause analysis of impact incidents based on predicting the potential impact energy levels. This enables more targeted predictive maintenance, which is especially significant in the aviation industry, where any impact incidents can have catastrophic consequences.Composite Structure
Increasing predictability in the response of an AI-assisted stall recovery system in complex stall conditions by expanding the knowledge-base of AI
Get PDFPresented at: 13th EASN International Conference on: Innovation in Aviation & Space for opening New Horizons 05/09/2023 - 08/09/2023 Salerno, ItalyThe environment in the cockpit of commercial aircraft is becoming increasingly complex due to the introduction of automation systems. This complexity is especially evident when malfunctions take place, making it difficult for pilots to comprehend the interconnectedness of the systems and potentially leading to loss of control. This paper investigates a novel method for creating an Artificial Intelligence-based stall recovery assistant using Reinforcement Learning by training the agent to generate a stall and subsequently recover from it. This enables training in a large training space with a simple reward function, where the agent has the ability to develop a deep understanding of the environment. Tests show that the agent is able to recover from stall at a variety of altitudes while experiencing unreliable airspeed information originating from a blocked Pitot tube system and with a better response than all baseline agents. The results indicate that restricting AI is not always necessary and, further, that too many restrictions can lead to a system that learns only shallow features, causing it to be unreliable in unforeseen circumstances.13th EASN International Conference on: Innovation in Aviation & Space for opening New Horizons, 2023Journal of Physics: Conference Serie
L1 adaptive fault‑tolerant control of stratospheric airships
Get PDFAs the utilization of stratospheric airships becomes more prevalent, ensuring their safe operation becomes crucial. This paper explores the ability of an L1 adaptive controller to maintain fault tolerance in the actuators of a stratospheric airship. L1 adaptive control offers fast adaptation while separating adaptation and robustness. This makes the approach a suitable candidate for fault-tolerant control. The performance of the proposed design is compared to the Linear Quadratic Integral and Adaptive Sliding Mode Backstepping controllers. Simulation results show that the robustness of the airship model against faults is improved with the use of the L1 adaptive controller.CEAS Aeronautical Journa
Implicit large eddy simulation of the flow past NACA0012 aerofoil at a Reynolds number of 1x10^5
Get PDFIn this paper, the implicit Large Eddy Simulation (iLES) incorporating an unstructured 3rd-order Weighted Essential Non-Oscillatory (WENO) reconstruction method is investigated on the flow past NACA0012 aerofoil at a Reynolds number of 1 × 10^5. The flow features involve laminar separation, transition to turbulent and re-attachment. Simulations are carried out in the framework of open-source package OpenFOAM with a 2nd-order Euler implicit time integration and Pressure-Implicit Splitting-Operator (PISO) algorithm is used for the pressure-velocity coupling. Conventional LES with Wall Adapting Local Eddy Viscosity (WALE) model is also carried out as a baseline. The results are compared with Direct Numerical Simulations (DNS) under the same flow configurations. The mean quantities such as pressure coefficient and the re-attached turbulent velocity profiles are in excellent agreement with the DNS reference. On the other hand, in the transitional region, the thickness of separation bubble obtained by both iLES and LES is thinner than the DNS. The current iLES approach has achieved a 35% reduction of mesh resolution compared to wall resolving LES and 70% reduction compared to DNS, while the accuracy is mostly satisfied.AIAA SCITECH 2024 Foru
Hypersonic boundary layer reduction with optimisation of the Hyshot II intake using numerical methods
Get PDFThe Hyshot project demonstrated that the quality of flow in a scramjets combustion chamber is essential to achieve critical mass flow condition in a small profiled supersonic combustion chamber. This investigation utilises a steady RANS and real gas thermal model to explore boundary layer growth over various comparable compression ramp profiles in a hypersonic freestream condition. The results in this investigation suggested that given a constant net flow deflection angle and ramp length, the displacement thickness developing on a hypersonic compression ramp is inversely proportional to the magnitude of static pressure the ramp produces at the wall, where the highest pressures theoretically achievable are that of an isentropic compression process. A quasi isentropic compression distribution was achieved when the rate of deflection along a ramp’s length is linear. The data collected also suggests that the difference in displacement thickness growth of the quasi isentropic ramp relative to the nominal flat plate increases as the flight Reynold’s number increases, where the displacement thicknesses has the potential to reduce by over 50% relative to an equivalent flat plate. Low Reynold’s numbers have found to yield the opposite effect, where isentropic turning of a hypersonic flow may increase the difference in these cases. Such reductions have been shown to theoretically allow for a critical mass flow rate in a two dimensional scramjet combustion chamber without requiring slot bleed systems, whilst achieving the required flow conditions for the auto-ignition of hydrogen. It is suggested that a scramjet design based upon these findings would still require some form of porous bleed system to compensate for the growth in the boundary layer as it expands about the compression ramp into the combustion chamber, which has potential to be incorporated onto an axisymetric design to optimise the effective mass flow rate per body diameter.AIAA SCITECH 2024 Foru
The first comprehensive chemical profiling of Vachellia gummifera (Willd.) Kyal. & Boatwr., a plant with medicinal value
Get PDFVachellia gummifera (Willd.) Kyal. & Boatwr. is a medicinal plant endemic to Morocco that has no documented studies on its chemical composition. In this study, the chemical composition of the water/methanol (4 : 1) extracts of air-dried leaf and stem samples of Moroccan V. gummifera was determined using UHPLC-MS and NMR. In total, over 100 metabolites were identified in our study. Pinitol was the major compound in both the leaf and stem extracts, being significantly more abundant in the former. Asparagine and 3-hydroxyheteroendrin were the second most abundant compounds in the stem and leaf extracts, respectively, though both compounds were present in each tissue. The other compounds included flavonoids based on quercetin, and phenolic derivatives. Eucomic acid, only identified in the stems and was the major aromatic compound distinguishing the leaf and stem profiles. Quercetin 3-O-(6′′-O-malonyl)-β-D-glucopyranoside was identified as the major flavonoid in the leaves but was also present in the stems. Other malonylated derivatives that were all flavonol glycosides based on myricetin, kaempferol, and isorhamnetin in addition to quercetin were also identified. This is the first report of eucomic acid and malonylated compounds in Vachellia species. This report provides valuable insights into the chemotaxonomic significance of the Vachellia genus.OCP Morocco.FP05is a collaboration between Mohammed VI Polytechnic University, Rothamsted Research and Cranfield UniversityChemistry & Biodiversit
Going Platinum: The European Journal of Soil Science at 75
No full textThe European Journal of Soil Science (EJSS) is published by Wiley on behalf of the British Society of Soil Science (BSSS) to fulfil its original mission to ‘publish an annual publication’. The Journal for Soil Science published its first issue in March 1949 (Figure 1, left) before a change of name to the European Journal of Soil Science (EJSS) in 1994. The current issue (Volume 75, Issue 2, March-April 2024; Figure 1, right) therefore marks our 75th Anniversary. In this Editorial, we (the Senior Editorial Team of the EJSS; Figure 2) review briefly how the journal has evolved over the last three-quarters of a century and look forward to both the challenges and opportunities that the future holds.European Journal of Soil Scienc
Diversity-based heuristic search for multiple-asteroid tours
Get PDFAn asteroid tour is a sequence of asteroid flybys performed by a spacecraft in a single mission. Visiting different types of asteroids would be of a great scientific return, but planning such type of mission is highly complex. This is because the combinatorial problem of selecting sequences of asteroids is coupled with optimal control problem of finding viable trajectories in terms of transfer times and manoeuvre locations. The combinatorial problem can be tackled with heuristic algorithms that explore the search space to find optimized flyby sequences of asteroids. This paper proposes a search strategy to increase the diversity of the set of flyby sequences found from the resolution of the optimization problem. The goal is to find a tree exploration method that will improve the quality of the solutions by increasing the number of targets encountered and eliminating duplicated sequences while preserving the average ∆v cost. A diversity measure for a set of solutions is defined based on the ∆v cost of the transfer and the nature of the asteroids in the sequences. A variant of the Beam Search (BS) algorithm, referred to as Diversity Search (DS), is tested. Unlike BS, the DS algorithm eliminates duplicated sequences from the final set of solutions. New asteroid tours are found, allowing to reach targets with a higher inclination or eccentricity, but the average ∆v of a flyby sequence is higher than solutions found with BS. A hybrid search strategy using BS and DS is explored. The goal is to reduce the search space with respect to two criteria: ∆v and diversity score. By pruning the search space according to ∆v first, the hybrid search algorithm is able to generate a diverse set of asteroid tours while preserving the total ∆v of the solutions. Compared to DS, less new asteroids are encountered in the solutions but the average ∆v remains similar to results obtained with BS.2024 IEEE Aerospace Conferenc
Emerging contaminants: a One Health perspective
Get PDFEnvironmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN’s Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.The Innovatio
Utilising Digital Image Correlation for the Characterisation of Ground Shock from Buried Charges
Get PDFPaper presentation to the Defence and Security Doctoral Symposium 2023 DST