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Propeller Design for Hydrogen-Electric Aircraft
Get PDFWith increasing interest in hydrogen aviation over the past several years, Proton Exchange Membrane Fuel Cell (PEMFC) powertrains have become a leading candidate for propelling short to medium haul flights. PEMFCs facilitate an electro-chemical reaction between hydrogen and oxygen to power electric motor driven-propellers. Existing powertrain modeling workflows typically employ generic look-up surfaces called propeller maps for propulsor performance. These are often unrepresentative of real blade geometries and assume equal performance across propeller diameters and rotation rates. In this study, Blade Element Momentum Theory (BEMT) is coupled to a PEMFC powertrain model developed in OpenConcept to afford an improvement in simulation fidelity and -- critically -- overall performance of the powertrain. A regional aircraft (DHC-8) with a PEMFC powertrain was modeled with a default propeller map from OpenConcept to serve as a performance baseline. Subsequently, BEMT was used to develop a propeller map where the geometry of the propeller and its performance at prescribed flight conditions are known. This map was evaluated against the baseline with and without a safety margin penalty and showed that powertrain optimization is sensitive to propeller design: an increase in weight margin of 2 tonnes combined with reductions in Balance of Plant and fuel masses of 1.2 tonnes and 89 kg were observed. Additional fidelity for thermal, structural and acoustic models unlocked by BEMT are presented. An extension of the modeling to incorporate aeroacoustic analysis is included to demonstrate the far-reaching impacts of including low-order propeller simulation into the design framework
Dataset for Nonlinear viscoelastic models improve characterisation of 6 DOF intervertebral disc load response at low strain rates
No full textThe data presented in this file comprises the 6 DOF position control data from tests performed on 6 porcine lumbar isolated spinal disc specimens using a triangular displacement waveform at a frequency of 0.1Hz. Data is presented relative to the centre of the intervertebral disc. The final three cycles are presented here. For each of the six specimens and for each of the six axes, data is provided for the applied displacement and each of the 6 resulting loads (forces and moments). The principal elements (highlighted in the tables) occur when the direction of applied displacement and measured load are the same - for example, axial torsion displacement (RZ) and torsional load (MZ). The data has been filtered to remove unwanted noise but no other pre-processing steps have been performed on this data - for example, cycle averaging and offsetting the central point to the origin
A Novel Stator Current Estimation Method Based on Embedded Linear Hall Sensors in FSCW-SPMSM
Get PDFEmbedded magnetic encoder (EME) has emerged as a cost-effective and compact solution for rotor position detection in permanent magnet synchronous motors (PMSMs), integrating linear Hall sensors within the motor cavity to detect permanent magnet fields (PMF) and extract rotor position. While conventional EME system prioritize suppressing armature reaction field (ARF) disturbances for high-precision position estimation under load, this article innovatively exploits ARF as information carriers, proposing a linear Hall-based current estimation methodology that transforms interference into a sensing resource. Through decoupled analysis of d/q-axis current-induced amplitude-phase modulation effects on magnetic flux density (MFD) signals at both slot-opening types in fractional-slot concentrated winding permanent magnet synchronous machines (FSCW-PMSMs), this method establishes a relationship between orthogonal currents and electromagnetic signatures. Capitalizing on the inherent immunity of in-phase slot-openings to ARF, it achieves effective separation of PMF interference during loaded operation. Furthermore, it comprehensively accounts for nonideal factors such as Hall sensor misalignment and magnetic saturation, and the algorithm directly quantifies d/q-axis current variations, achieving online stator current monitoring and redundant backup capabilities. The proposed method is validated via simulations and experiments, demonstrating its effectiveness in current estimation.</p
A Novel Stator Current Estimation Method Based on Embedded Linear Hall Sensors in FSCW-SPMSM
Get PDFEmbedded magnetic encoder (EME) has emerged as a cost-effective and compact solution for rotor position detection in permanent magnet synchronous motors (PMSMs), integrating linear Hall sensors within the motor cavity to detect permanent magnet fields (PMF) and extract rotor position. While conventional EME system prioritize suppressing armature reaction field (ARF) disturbances for high-precision position estimation under load, this article innovatively exploits ARF as information carriers, proposing a linear Hall-based current estimation methodology that transforms interference into a sensing resource. Through decoupled analysis of d/q-axis current-induced amplitude-phase modulation effects on magnetic flux density (MFD) signals at both slot-opening types in fractional-slot concentrated winding permanent magnet synchronous machines (FSCW-PMSMs), this method establishes a relationship between orthogonal currents and electromagnetic signatures. Capitalizing on the inherent immunity of in-phase slot-openings to ARF, it achieves effective separation of PMF interference during loaded operation. Furthermore, it comprehensively accounts for nonideal factors such as Hall sensor misalignment and magnetic saturation, and the algorithm directly quantifies d/q-axis current variations, achieving online stator current monitoring and redundant backup capabilities. The proposed method is validated via simulations and experiments, demonstrating its effectiveness in current estimation.</p
People-Led Digitalisation (P-LD) Metrics in UK Manufacturing:An Analysis of Workforce Impact Assessment
Get PDFKey Points People and Culture are critical: The UK government‑backed Made Smarter Innovation programme notes that one of the major barriers to adopting digital technologies is “people and organisational culture.” People-Led Digitalisation Metrics are not widely used: Based on responses by 410 professionals within UK manufacturing, most companies either do not use or have not considered using people‑focused metrics for assessing the impact ofdigitalisation on their workforce. Unwillingness is not about data collection: Low use of people-led metrics is not related to data collection. Our survey revealed metrics where data was easy to collect were assessed as ‘modest’ in terms of Usefulness. The same results were found for difficult to collect metrics
Insight into the alkali metal poisoning sensitivity of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2</sub> catalysts for NO<sub>x</sub> abatement via machine learning and in situ Raman spectroscopy
Get PDFV2O5–WO3/TiO2 (VWTi) catalysts for NH3–SCR suffer severe poisoning by alkali metals, especially K, yet the site-specific poisoning mechanism remains unclear. Herein, we elucidate the poison mechanism based on a comprehensive investigation consisting of experimental work, theory calculation, and machine learning, conducted by controlling the VOx density and K/V ratio. Using a variety of characterization techniques, we found that the SCR activity of a VWTi catalyst was governed by its redox ability and the Lewis acidity dominated by V4+. The terminal V=O group is a Lewis acid and can adsorb NH3, while the bridging V–O–V group serves as a redox center, capable of activating NO/O2. K poisons a VWTi catalyst by attacking the strong Brønsted acids first and then the strong Lewis sites, resulting in a nonlinear progression of activity decline, which is slow initially but accelerates with increasing K accumulation. This phenomenon is especially evident for high–V loading catalysts dominated by the polymeric VOx species. Density functional theory calculations reveal that K poisons VWTi catalysts by binds K to the terminal V=O sites, forming the chemically inactive KVO3 compound and weakening the NH3 adsorption on the neighboring VOx. This work offers a comprehensive understanding of the site-specific sensitivity of VOx species to alkali metal poisoning and provides important insights to the deactivation process, which could be used to design practical VWTi catalysts for commercial applications.</p
Comparative Evaluation of Optimization Algorithms for Truss Shape Design
Get PDFComputational optimization methods are increasingly employed in structural engineering to achieve efficient and reliable designs. This paper introduces a framework that integrates finite element analysis (FEA) with three optimization algorithms – Derivative-Free Optimization (DFO) Nelder- Mead, Particle Swarm Optimization (PSO), and Genetic Algorithms (GA) – to perform shape optimization of truss structures. Unlike previous works that studied these algorithms separately, this paper benchmarks them under identical problem formulations, providing a fair basis for selecting suitable methods in structural design optimization. The framework ensures a standardized problem setup, allowing a fair comparison of algorithmic performance in terms of convergence speed, optimization quality, consistency, and flexibility. Detailed steps for implementation using Python libraries are provided to facilitate future implementation and further development by other researchers. Applications to several truss configurations, including cross-braced bays and bridge systems, demonstrate that while all algorithms achieved significant displacement reductions, distinct trade-offs exist: DFO provides rapid and consistent results with minimal computational overhead; PSO converges quickly with high-quality solutions; and GA offers strong adaptability but at the cost of higher computational effort. By establishing a reproducible computational workflow, this study provides insights into algorithm selection for structural optimization and highlights Python’s suitability as a platform for applied engineering computations
Parental and Adolescent Positive Affect and Optimism as Predictors of Post-surgical Mood and Functioning in Adolescents Undergoing Spinal Fusion Surgery
Get PDFObjectives: – While most adolescents display a steady recovery trajectory following surgery, some develop chronic postsurgical pain (CPP), which can significantly impact their functioning. Psychosocial factors are known to play a role in the recovery from pain following surgery, but positive psychosocial factors have received little attention in the literature. This study aims to address this gap by investigating parental and adolescent positive affect and optimism as predictors of post-surgical pain recovery and positive outcomes in adolescents. Methods: – This study uses data collected as part of a larger longitudinal project that involved administering questionnaires to adolescents and their parents over multiple timepoints. Adolescent participants aged 12 – 18 years old with a diagnosis of Adolescent Idiopathic Scoliosis, and scheduled for spinal fusion surgery, were recruited across four Belgian hospitals along with their parents. Structural Equation Modelling was used to investigate how parental and adolescent positive affect and optimism predicted post-surgical outcomes, including mood, quality of life and functional disability in adolescents. Results: – The study comprised 94 adolescent-parent dyads. Parental optimism before surgery predicted increased adolescent mood following surgery. Adolescent positive affect before surgery predicted increased mood and decreased pain intensity following surgery, while adolescent optimism predicted increased quality of life. None of the optimism or positive affect variables were significantly related to adolescent functional disability following surgery. Discussion: – Study findings identify parental and adolescent positive affect and optimism as potential predictors of post-surgical recovery and positive outcomes in adolescents. However, the multifaceted and complex nature of these relationships warrants further investigation.</p
Fluid Dynamics of Rotors Through Dynamic Transition
Get PDFUrban Air Mobility requires vehicles (UAMs) that operate in close proximity to buildings, particularly in take-off and landing phases. Such operation results in the aircraft encountering significant unsteadiness in the form of large amplitude gusts. Control in these transitional areas of flight is paramount to safety, and therefore rotor performance during transition must be understood. To this end, the Bath University Low-speed eVTOL Test-Rig (BULLET) has been significantly upgraded to deliver transition rates up to 10pi/9 rad/s, designed to probe the dynamic behavior of rotors through dynamic transitions and gust encounters. To the authors' knowledge these represent the fastest experimental transitions in the literature. Coupled with stereoscopic Particle Image Velocimetry, this study presents for the first time flow visualization of a rotor undergoing dynamic motion. The inflow PIV indicates an asymmetry of blade loading during transition, which is magnified by rapid transition despite the net thrust remaining unchanged. Blade angle of attack distributions are observed varying by up to 0.5deg. However, force decomposition demonstrates a lack of any unsteady overall thrust response from the rotor in response to the dynamic motion. This is corroborated by PIV analysis of both the wake and inflow to the rotor disc which show no introduction of unsteady effects
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