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Communication RSSI prediction and validation framework for advanced air mobility
Get PDFThis paper proposes a communication signal strength prediction and validation framework for the use of advanced air mobility. Advanced air mobility, including urban air mobility and unmanned aerial vehicles, requires a scalable, safe, and seamless communication infrastructure different from conventional aircraft. This paper proposes a hybrid regression-based prediction method that combines synthetic data generated from a ray-tracing model and real flight test data in the urban airspace and uses k-fold cross-validation to evaluate the predicted signal strength. The results show that the proposed framework provides reliable performance indices, effectively mitigating the insufficiency of flight data. This research will enable evaluating the communication infrastructure and identifying high-risk areas for advanced air mobility stakeholders.Innovate UKThis work was conducted as part of “Advanced Air Mobility: Communication Evaluation for Safe and Seamless Operations”, supported by Innovate UK (grant number 10117151) and Korea Agency for Infrastructure Technology Advancement (grant number RS-2024-00412531).2025 International Wireless Communications and Mobile Computing (IWCMC
Modelling and evaluation of electrified regional aircraft propulsion systems
Get PDFElectric propulsion (EP) and hybrid electric propulsion (HEP) are novel concepts that
significantly impact the future aircraft design and emission reduction. These novel technologies can be used to decarbonise air transportation, especially regional aircraft in short
term future. Despite the potential benefits, their implementation challenges such as durability, reliability, architectural design, subsystem health state impacts, and the dynamic
behaviour of various components in an integrated propulsion system have not been fully
explored. The methodologies and results in literature varied significantly, they either
focused on parametrically varying technology levels for aircraft weight and range sensitivity, or considered detailed subsystem design for specific purposes. Moreover, an im-
portant aspect not fully considered in most publicly available studies is to utilise fuel cell
and hydrogen as the primary power supplier and energy source for future electric regional
aircraft.
To fill in these gaps a modular component based simulation framework is developed
in this work, aiming to model and assess the design and off-design performance of integrated hybrid electric aircraft propulsion systems by capturing the characteristics, in-
teractions and interdependencies of its components. The developed component models
include the main devices: batteries, fuel cell system, power electronics such as converters
and inverters, and electric motors. Another key feature of this simulation framework is
its multi-fidelity natural. The low-fidelity models enable fast system analysis and parametric studies in various aspects for holistic mission, whereas the high-fidelity ones allow
detailed subsystem sizing, architectural design and evaluation, and performance assessment. In this study, power electronics and electric motors are modelled in both low fidelity
and high fidelity. For power electronics, the switching circuit elements are not included
and their control mechanisms are realised by simple PI controllers for low fidelity models;
whereas complete switching circuit systems are modelled to simulate their power losses
and control logic for high fidelity models. For electric motor systems, dq model with PI
control system are used as low fidelity models whereas a MotorCAD based PMSM performance map, with ‘Id = 0’ control strategy and SVPWM modulation inverter circuit are
used as high fidelity models.
The simulation framework was applied to study a 50 PAX, ATR42 like regional aircraft. Two forms of propulsion architectures were investigated: a pure PEMFC powertrain and a hybrid electric one. Based on the developed electric models and simulation
framework, various cases and scenarios not studied in literature were investigated. For
pure PEMFC system, the impacts of air mass flow rate and air supply pressure variation
on fuel cell based system performance were investigated; The degradation impacts of fuel
cell and battery on the system performance and sizing were also studied; A thorough discussion on fuel cell multi-stack architectural design was presented. Whereas for hybrid
electric system, a comparative study between hybrid battery, hybrid fuel cell and hybrid
battery/fuel cell propulsion system was conducted. The study evaluated key factors that
can affect the electric system weight, such as mission length, hybridisation level, battery
cycling number, etc. All these problems are significant and need to be solved before
implementing the novel electrical propulsion technologies on regional aircraft.
Key findings and important conclusions were drawn from these case studies. For pure
PEMFC system, it was found that the FC system normally exhibited higher efficiency at
low power level (e.g. approximately 45% at top of climbing and 58% during descent).
Therefore, a slight over-sized FC system can help improve the efficiency performance;
Secondly, the effects of FC air supply pressure and mass flow rate on FC system efficiency
and robustness were investigated. It was found that, although there was reduction in
FC stack efficiency when keeping a relatively low FC air supply pressure, the overall
FC system efficiency was improved throughout flight mission. Also, a potential risk of
low air supply rate was identified and a control strategy balancing efficiency and system
reliability was proposed; Thirdly, FC degradation can cause imbalance performance of the
whole multi-stack FC system. In this study, a 10% voltage and current degradation from a
single FC was used, and it was found that such single cell level degradation can cause the
whole FC system malfunction for some flight phases, which was detrimental. A detailed
solution to avoid the malfunctioning risk was discussed in this study. For hybrid electric
system, it was found that, under current and short-term technology level, FC based hybrid
propulsion system generally had weight advantages over battery based one for regional
aircraft. Specifically, a case study demonstrated that pack-level battery S.E. was expected
to reach around 335-, 406-, and 543 Wh/kg to compete against the hybrid fuel cell system
for 200-, 300-, and 600 nmi mission for the same power profiles. This required huge
technology improvement for battery, since its cell level state-of-art S.E. was merely 250
Wh/kg when the research was initiated. Moreover, when battery cycling degradation was
considered, further battery technology improvement was required.PhD in Aerospac
A comparative analysis of hybrid sensor fusion schemes for visual–inertial navigation
Get PDFVisual Inertial Odometry (VIO) has been extensively studied for navigation in GNSS-denied environments, but its performance can be heavily impacted by the complexity of the navigation environments such as weather conditions, illumination variation, flight dynamics, and environmental structure. Hybrid fusion approaches integrating Neural Networks (NN), especially Gated Recurrent units (GRU) with the Kalman filters (KF), such as Error-State Kalman Filter (ESKF) have shown promising results mitigating system nonlinearities due to challenging environmental conditions data issues, there is a lack of systematic studies quantitively analysing and comparing performance differences unhand. To address this gap and enable robust navigation in complex conditions, this study proposes and systematically analyses the performance of three hybrid fusion schemes for VIO-based navigation of Unmanned Aerial Vehicles (UAV). These three hybrid VIO schemes include Visual Odometry (VO) error compensation using NN, KF error compensation using NN, and prediction of Kalman gain using NN. The comparative analysis is performed using data generated in MATLAB incorporating the Unreal Engine involving diverse challenging environmental conditions: fog, rain, illumination level variability and variability in the number of features available for extraction during the UAV flight in the urban environment. The results demonstrate the performance improvement achieved by hybrid VIO fusion schemes compared to ESKF-based traditional fusion methods in the presence of multiple visual failure modes. Comparative analysis reveals notable improvement achieved by method 1 with enhancements of 93% in sunny, 91% in foggy and 90% in rainy conditions than the other two hybrid VIO architectures.IEEE Transactions on Instrumentation and Measuremen
Impact of cold-wire gas metal arc welding (CW-GMAW) parameters on microstructure and microhardness characteristics in repairing S275JR structural steel
Get PDFThis study investigates the influence of adding a cold wire during gas metal arc welding (CW-GMAW) for repair of S275JR structural steel. The research is aimed at improving repair productivity through increased deposition rates with enhanced performance. During weld repair, multiple passes induce large number of thermal cycles and a huge thermal gradient on the material which has an adverse effect on the material’s properties. This is largely due to the microstructural changes that occur during the process. In this work, a systematic approach has been adopted to explore the effects of varying gas metal arc welding (GMAW) parameters, including wire feed rate, welding current, voltage, travel speed, and specifically cold-wire feed speed on the heat affected zone (HAZ) microstructure and hardness. Macrostructural examination highlights significant alterations in the heat affected zone (HAZ) region, with marked microhardness changes in both WM and HAZ. Cold-wire addition led to a reduction in the HAZ area, depth of weld metal penetration, and significantly reduced the impact of imposing thermal cycles on the HAZ of the welded samples. Additionally, microstructural analysis was conducted using a standard optical microscope to correlate the observed hardness variations with microstructural transformations in the weld metal and heat affected zone (HAZ). The findings reveal that specific combinations of CW-GMAW parameters can significantly influence the microstructure and thereby hardness, suggesting that with careful control of these parameters, it would be possible to do faster repair with minimal loss of integrity for critical structural steels.Funding for this project was provided by Petroleum Technology Development Fund in Nigeria, under the PTDF OSS scholarship scheme no. PTDF/OSS/20PHD123.TMS 2025 Annual Meeting & Exhibitio
Signal-to-interference-noise-ratio density distribution for UAV-carried IRS-to-6G ground communication
Get PDFThis paper investigates the probability distribution of the signal-to-interference noise ratio (SINR) for a 6G communication system comprising a multi-antenna transmitter, an intelligent reflecting surface (IRS) and a remote receiver station. A common assumption in the literature is that the density distribution function for SINR and signal-to-noise ratio (SNR) of an IRS-to-ground communication follows a Rayleigh and Rician distribution. This assumption is essential as it influences the derivation of the properties of the communication system such as the physical layer security models and the designs of IRS controller units. Therefore, in this paper, we present an analytical derivation for the density distribution functions of the SINR for an IRS-to-6G ground communication ameliorating the typical assumptions in the literature. We demonstrated that the SINR density function of an IRS-to-6G ground communication contains a hypergeometric function. We further applied the derived density distribution function to determine the average secrecy rate for passive eavesdropping.Engineering and Physical Sciences Research Council (EPSRC)This work was supported by EPSRC Communications Hub for Empowering Distributed Cloud Computing Applications and Research (CHEDDAR) Project under Grant EP/X040518/1 and Grant EP/Y037421/1IEEE Acces
Unsteady flow interactions and ground plane proximity in a coupled compact intake-fan in crosswind
Get PDFThe assessment of the crosswind flow separation mechanisms and resulting distortion for compact intakes can be a key contributor for the design of viable large civil aeroengines. Under crosswind conditions, the intake aerodynamics are strongly influenced by both the fan and the ground plane. However, the impact of key design parameters, such as ground clearance, on the intake flow distortion is not fully understood. This study investigates the effects of a large variation in ground clearance on the intake-fan unsteady aerodynamics using an Unsteady Reynolds-Averaged Navier-Stokes fully coupled with a rotating fan stage. The work includes an assessment of the unsteady swirl distortion and the unsteady peak distortion events. The findings show that increased ground clearance can have adverse effects for the considered compact intake design. Gross separation can occur at lower crosswind velocities and arise at the intake lower section due to mass flow redistribution. When the ground clearance is increased, the gross separation on the windward side of the intake occurs at a greater crosswind velocity but exhibits greater levels of unsteady intake flow distortion. Overall, intake designs should be assessed at the expected ground clearance as the distortion and the onset of separation can vary substantially.L. Lobuono was supported by the Engineering and Physical Sciences Research Council [grant number EP/W524529/1], Rolls Royce plc., and Cranfield University. D. MacManus and R. Christie were partially funded by Innovate UK ATI FANFARE project (Ref: 113286).59th 3AF International Conference on Applied Aerodynamics, 202
Designing and testing of HDPE–N2O hybrid rocket engine
No full textHybrid Rocket Engines (HREs) combine the advantages of solid and liquid propellants, offering thrust control, simplicity, safety, and cost efficiency. Part of the research on this rocket architecture focuses on optimising combustion chamber design to enhance performance, a process traditionally reliant on time-consuming experimental adjustments to chamber lengths. In this study, two configurations of HREs were designed and tested. The tests aimed to study the impact of post-chamber lengths on rocket engine performance by experimental firings on a laid-back test engine. This study focused on designing, manufacturing, and testing a laid-back hybrid engine with two chamber configurations. The engine features a small combustion chamber, an L-shaped mount, a spark ignition, and nitrogen purging. Data acquisition includes thermocouples, pressure transducers, and a load cell for thrust measurement. Our experimental findings provide insights into thrust, temperature gradients, pressure, and plume characteristics. A non-linear regression model derived from the experimental data established an empirical relationship between performance and chamber lengths, offering a foundation for further combustion flow studies. The post-chamber length positively impacted the engine thrust performance by 2.7%. Conversely, the pre-chamber length negatively impacted the performance by 1.3%. Further data collection could assist in refining the empirical relation and identifying key threshold values.The authors would like to thank the School of Aerospace, Transport and Manufacturing, Cranfield University and the Centre for Autonomous and Cyberphysical Systems for their financial backing and technical guidance.14th EASN International ConferenceEngineering Proceeding
“In-situ” x-ray imaging technology for material and manufacturing science: a review
Get PDF“In-situ” X-ray imaging has become a powerful tool in materials and manufacturing science, enabling real-time observation of critical processes. However, access to X-ray facilities remains highly competitive due to limited availability, high operational costs, and technical complexity, restricting its use to a few research groups worldwide. This review addresses this challenge by providing a comprehensive analysis of X-ray imaging technologies, their historical development, and recent advancements in “in-situ” X-ray imaging. It explores applications across various materials and manufacturing processes, including welding, additive manufacturing (AM), casting, high-temperature furnaces, and novel materials. Key topics such as heat transfer, melt pool dynamics, solidification, microstructure evolution, and defect formation in manufacturing processes are systematically examined. Additionally, the review highlights the potential of “in-situ” X-ray imaging for discovering novel materials and advancing manufacturing technologies. It discusses current limitations, particularly the constraints of existing X-ray facilities, and outlines future directions for enhancing this technology. Expanding access to high-resolution X-ray imaging is crucial for accelerating advancements in materials and manufacturing. Integrating artificial intelligence and simulation models will further enhance its capabilities. Achieving these improvements requires upgrading existing X-ray facilities and developing new systems capable of capturing high-resolution, real-time imaging of complex material processes.European Research CouncilJournal of Manufacturing Processe
Assessment of fatigue crack initiation after overloads with substructure-sensitive crystal plasticity
Get PDFMicrostructure-sensitive fatigue initiation prognosis approaches typically assume uniform periodic loading and often overlook in-service overloads, which increase uncertainty and reduce life prediction accuracy. Similarly, certification efforts rarely evaluate experimentally the impact of different overloads due to the prohibitive costs. Therefore, predictive models that estimate overload effects on fatigue initiation damage without extensive experimental data are valuable to improve prognosis approaches. However, the literature lacks microstructure-sensitive approaches capable of assessing overload effects with models that simultaneously predict monotonic and cyclic responses without recalibration. This work presents a novel strategy to predict the effects of overloads on early cyclic damage by evaluating the refinement dislocation structures. A substructure-based crystal plasticity approach relies on independent parameterizations from monotonic and cyclic loading to predict overload responses, without requiring additional experiments. The model agreement with macroscale experiments was further validated by comparing dominant mesoscale structures after overloads in single- and poly-crystals for metals and alloys. The analysis also identified overload-resistant crystal orientations and demonstrated that overloads increase the likelihood of initiating fatigue cracks in low apparent Schmid factor grains under low-amplitude fatigue. We conclude by discussing the value of material-invariant mesoscale parameters to rank overloads effect for materials and loading conditions for which no experiments are available.GMC thanks The EPSRC, UK for funding under EPSRC grant EP/R034478/1.International Journal of Fatigu
Data and secondary analysis for High-Precision Machining Behavior of the Single Crystal Scintillator, bismuth germanate (Bi4Ge5O12)
No full textSimulation data: meshes, input data for the JH-2 model, output graphs for compression tests and milling simulations.
Compression tests: experimental stress-strain data for BGO during quasi-static compression and split tests, output graphs and figures
3D microscopy: 2D images and 3D images, CSV files containing 3D data for milled BGO
SEM: scanning electron microscopy images taken of milled BGO
ra: white light interferometry data collected for milled BGO (proprietory .sur, and .txt (ASCII)); data processing (proprietory Taly Map Gold .mnt file and PDF of workbook); extracted roughness and waviness traces (.csv) and plots (.jpg)This data set supports a study on the machinability of a single crystal scintillator, Bismuth Germanate (BGO), a material widely used in Time-of-Flight Positron Emission Tomography (TOF-PET). In this study, the Johnson-Holmquist 2 (JH-2) material model was used to simulate the micro-milling process for BGO. Key parameters for the JH-2 model were estimated from experimental data from quasi-static compression and split tests. Simulations performed using different machining parameters were compared with equivalent machined samples and were able to successfully replicate the conditions observed. This dataset compiles the data and meshes used during the simulations, the compression and split test data, microscopy data for the machined sample, and white light interferometry data used to calculate machined surface roughness and the post-processing required to extract the roughness values.Engineering and Physical Sciences Research Council (EPSRC