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Mechanical behaviour of a novel 3D-printed cubic cellular structures under bending loads: an experimental and numerical analysis
No full textThis research presents a novel 3D-printed cubic cellular structure fabricated using fused deposition modelling (FDM) with a no-infill technique. It reports on both experimental and numerical analyses of these cubic cellular structures, examining configurations with 1, 2, 3, and 4 cell layers subjected to 3-point loading. The experimental results suggest that there is a correlation between the number of cell layers and the structural response under bending. A distinct transition in mechanical behaviour is observed from the 2-cell to the 4-cell structures, characterised by a linear trend, with a notable reduction in the amount of deflection as the number of cell layers increases. Meanwhile, the 1-cell layer structure exhibits a bending-dominant deformation. The results of the finite element model clarify the influence of the strut diameter and the number of cell layers on the bending behaviour, aligning well with the experimental findings. Overall, the 1-cell layer structures demonstrate bending dominance, whilst the 3- and 4-cell layer structures exhibit linear dominance. The 2-cell configuration uniquely combines both bending and linear behaviours.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior|Finance Code 001, Conselho Nacional de Desenvolvimento Científico e Tecnológico|PQ- 305553/2023-2.Advanced Vehicle Engineering Centre at Cranfield UniversityProgress in Additive Manufacturin
Defect force and viscous mechanical energy generation in aerodynamic flows
Get PDFA defect integral analysis of the 2D compressible steady-state viscous flow about unpowered aerodynamic bodies is derived in this paper based on momentum and mechanical energy conservation. The defect flowfield is obtained by subtracting the equivalent inviscid flowfield from the real viscous flow, thereby retaining only entropy-related perturbations within boundary and free shear layers that contribute to viscous drag and mechanical loss generation. First, a defect momentum balance is derived that introduces the notion of the defect force, its far-field decomposition, and its relation to the conventional viscous drag definition (profile drag minus wave drag). Next, a mechanical defect energy formulation is carried out in the relative reference frame that offers a means of explicitly and implicitly calculating the mechanical energy losses, including, for the first time, compressibility-induced losses for both adiabatic and nonadiabatic flows. Finally, a defect mechanical formulation is derived in the absolute reference frame that provides an energy-based decomposition of the defect and conventional drag power into its mechanical energy loss and viscous excess mechanical energy constituents. The result is a clear identification and traceability of the evolution of viscosity-induced mechanisms related to viscous drag, mechanical energy loss generation, and recoverable viscous mechanical energy, relevant for boundary-layer ingestion propulsion. The formulations are numerically and experimentally advantageous because they only require integration across the shear layer height, and all the momentum and mechanical energy terms can be implicitly calculated from surface integrations of readily available numerical and experimental data.Journal of Aircraf
Mega-fortresses in the South Caucasus: new data from Southern Georgia
Get PDFContemporary global research on large settlements (both urban and non-urban) has prompted a reassessment of factors driving population aggregation. The rise of large fortress settlements in the South Caucasus c. 1500-500 BCE has the potential to contribute to this discussion. A comprehensive aerial and ground-based survey of the large fortress-settlement of Dmanisis Gora reveals its distinctive character. Substantial defensive walls and stone
architecture in the outer settlement contrast with evidence for apparent low intensity of occupation. These results have implications for pastoralist-driven population aggregation in Eurasia and beyond.Support for the project came from the Gerald Averay Wainwright Fund, the British Institute at Ankara (BIAA), and a Gerda Henkel Foundation Project Grant (AZ 33/F/22). (Gerda Henkel Foundation Project Grant|AZ 33/F/22)Antiquit
Improvements of electrochemical water splitting efficiency by using economically viable Co/CoPs/TiO₂/NiF electrocatalysts
Get PDFJiang, Ying - Associate SupervisorThe drive for sustainable energy solutions has led to the search for efficient and
cost-effective electrocatalysts for green hydrogen production via electrochemical
water splitting (EWS). This study addresses the limitations of precious metal-
based catalysts by investigating alternative, earth-abundant materials. This
research introduces a novel Co/CoPs(240)/TiO₂/NiF electrocatalyst, synthesized
using deep eutectic solvent (DES)-mediated electrodeposition of Co and cobalt
phosphides (CoPs) on TiO₂-coated nickel foam (NiF) substrate.
Electrophoretic deposition of TiO₂ nanoparticles was successfully applied to NiF,
resulting in a smooth and even surface. On this TiO₂-coated substrate,
subsequent Co/CoPs deposition produced unique hexagonal and cauliflower-like
structures with a uniform distribution of Co and P. Energy dispersive X-ray
spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction
(XRD) were used to confirm these features. Optimizing the Co/CoPs deposition
times significantly reduced the hydrogen evolution reaction (HER) overpotential
to 34.42 ± 4.2 mV at 10 mA cm⁻² in 1 M KOH. Remarkably, the
Co/CoPs(240)/TiO2/NiF catalyst required only 27.43 mV with a Tafel slope of
48.35 mV dec⁻¹. Stability tests demonstrated minimal performance degradation
after 5000 cycles and 40 hours of operation, demonstrating excellent durability.
This optimized catalyst outperformed Co/CoPs(240)/NiF, commercial 10% Pt/C
electrodes, and other reported catalysts.
The oxygen evolution reaction (OER) performance also highlighted the catalyst's
efficiency, with an overpotential of 331.70 mV at 10 mA cm⁻² in 1 M KOH and a
Tafel slope of 73.96 mV dec⁻¹. Stability tests revealed minimal performance
degradation after 1000 cycles. Furthermore, a full water electrolyser system using
Co/CoP(240)/TiO2/NiF electrodes achieved a total voltage of 1.612 V at 10 mA
cm⁻², indicating the practical viability of the optimized electrodes for water splitting
applications.
The remarkable performance of the Co/CoPs(240)/TiO₂/NiF electrode is primarily
due to the presence of the TiO₂ layer, which enhances the surface area and acts
as a catalyst promoter through synergistic effects and enhanced charge transfer
kinetics. This research suggests that incorporating an intermediate TiO₂ layer can
promote the catalytic activity of other catalysts as well.
In conclusion, this study presents an effective and economical alternative to noble
metal-based electrocatalysts for water splitting. By integrating TiO₂ with Co/CoPs
on a NiF substrate, the research advances the development of high-performance,
low-cost catalysts and contributes to the sustainable production of green
hydrogen.MSc by Research in Energy and Powe
Assessment of primary care services operational resilience by patients: Implications for COVID-19 recovery
No full textWhile the National Health Service of the United Kingdom recovers from COVID-19, it's crucial to assess the impact of the dynamic capabilities within its healthcare services to ensure future public health protection. This study adopts mixed methods of literature review and surveys. Survey findings reveal that agility, flexibility, and building redundancy proved instrumental in reconfiguring resource foundations swiftly and fostering new partnerships. These actions were essential for sustaining service quality and efficiency. The analysis recommends that patients and healthcare professionals should co-design a technology-driven primary care service provision that is person-centric and digitally inclusive. Furthermore, primary care service stakeholders should develop targeted collaborations, and workforce development should be a priority to increase medical reserve in the healthcare system. This research provides empirical evidence, enabling the National Health Service to persist in enhancing dynamic capabilities and reinforcing resilience for anticipated and unforeseen future challenges.European Management Journa
In-situ triboelectric nanogenerator for energy self-cycling electrochemical systems in wastewater treatment
No full textEnhancing energy efficiency in wastewater treatment is essential for achieving carbon neutrality in the water sector. However, the potential and feasibility to recover in-situ mechanical energy from the complex and multidirectional fluid dynamics of aeration-induced flows remains underexplored. Here we present a self-sustaining treatment system that couples a coronal triboelectric nanogenerator (C-TENG) with membrane capacitive deionisation (MCDI) for energy self-cycling contaminant removal. The tailored C-TENG could harvest low-frequency water wave energy in aeration tanks to directly power the MCDI unit for the treatment of real wastewater. Both simulations and experimental validation were conducted to optimise the system configuration, obtaining sufficient energy recovery from a single 18 cm-diameter C-TENG unit and allowing the subsequent MCDI to effectively remove phosphorus (95 %) and a range of metal ions (70 %-80 % for Fe3+, Ni2+, Cu2+, Cr3+, Cd2+, and Pb2+) from real secondary effluent. Moreover, integrating 75 % energy recovery efficiency through self-regeneration reduced MCDI energy consumption to 0.26 kWh/m³, enabling low-energy ion removal and electric energy storage in the C-TENG//MCDI system, while supporting further treatment. This innovation introduces a scalable and sustainable approach that couples fluidic energy harvesting with electrochemical treatment, offering a viable route to upgrade existing wastewater infrastructure.This work was funded by the National Natural Science Foundation of China (No. 52370032). It was also supported by the National Key Research and Development Program of China (No. 2023YFC3706700) and the National Youth Talent Climbing Program of Northeast Normal University (No. 135515007).Water Researc
Surface reconstruction of La0.95Pr1.05CuO4 as an efficient bifunctional electrocatalyst for water splitting
No full textThe design of a cost-effective, stable, and efficient electrocatalyst for electrochemical water splitting is crucial for hydrogen generation. Non- and compositionally flexible Perovskites are a promising class of catalysts for catalyzing electrochemical water splitting. Herein, we report the synthesis of La0.95Pr1.05CuO4 raw (LPC-R) by the sol–gel method. Then, its surface reconstruction was done by immersing the catalyst in different concentrations of reductive sodium borohydride solution. As a result, an amorphous layer formed on the surface of the catalyst, as observed in scanning electron microscopy (SEM) and High-resolution transmission electron microscopy (HRTEM). The best catalyst, La0.95Pr1.05CuO4 (LPC-2), surface reconstructed by using 2 M sodium borohydride solution, was tested as a bifunctional catalyst and exhibited the lowest overpotential of 260 mV, 104 mV, and Tafel slopes of 54 mV dec−1 and 122 mV dec−1 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Moreover, it also exhibited more than 10 hours of stability. Surface reconstruction tailored electronic structure, and ion stoichiometry form active surface species that contribute to enhancing the catalyst's activity. This work illustrates an efficient strategy of surface reconstruction to improve the performance of as-synthesized catalysts for electrochemical water splitting.The Higher Education Commission (HEC) of Pakistan supported this work through grant no. HEC-NRPU 15745 and Commonwealth Split-site Scholarships.Nanoscal
Failure modes of CFRP panels under hypervelocity impact: the effects of strain rate between 1 km/s and 6 km/s
Get PDFStudying the effects of hypervelocity impacts on structural materials is essential for the aerospace and defense fields. However, there is a paucity of open-source and accessible data in the literature concerning the hypervelocity impact response of CFRP composites. This paper details our results from an experimental research program designed to aid in addressing this limitation by providing extensive data from multiple analysis techniques. This is part of a wider body of research focused on identifying failure modes and their evolution at elevated strain rates. Experimental work on the impact of commercially available CFRP composites at impact velocities between 1000 and 6000 m/s is presented and discussed. This work provides further validation for the response of an aerospace-relevant material to extreme loading conditions, with wider implications for the design and use of these structures in various industries. Preliminary results from optical imaging, HSV capture, SEM, VP-SEM, and target mass loss analysis are included and show a strain rate dependence in the CFRP material studied.This work was funded through an Engineering and Physical Sciences Council (EPSRC) Doctoral Training Partnership/studentship (20233/2023) to Cranfield University.17th Hypervelocity Impact Symposium 202
Multistatic synthetic aperture radar autofocus for back projection imaging of a moving target
Get PDFSynthetic Aperture Radar (SAR) plays a vital role in the surveillance of terrestrial and maritime targets, which are commonly in motion. As such, the ability to perform accurate real‐time focusing and localisation on moving targets, particularly those moving with complex motion, is desired. Many existing autofocus algorithms struggle to achieve this and rely on sub‐aperture processing of SAR data to estimate and compensate for phase errors attributed to unknown target motion. This paper presents a new metric‐based autofocus approach, called Localised Threshold Sharpness (LTS), which employs multistatic SAR data to localise and focus a target moving with up to six degrees of freedom motion on a real‐time, pulse‐by‐pulse basis. The algorithm is verified with experimental data, and its performance is compared against the performance of an existing measure of image sharpness suitable for pulse‐by‐pulse autofocusing, namely the intensity‐squared metric, with varying levels of added noise. Normalised cross‐correlation results demonstrate a resemblance of at least 80% between Multistatic SAR images focused via LTS autofocus and Multistatic SAR images ideally focused using target motion knowledge for signal‐to‐noise ratios above 3 dB.This work was funded by Defence Science and Technology Laboratory.Electronics Letter