20505 research outputs found
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Stress, strain, or displacement? A novel machine learning based framework to predict mixed mode I/II fracture load and initiation angle
Get PDFAccurate prediction of fracture load and initiation angle under complex loading conditions, like mixed mode I/II, is essential for reliable failure assessment. This paper aims to develop a machine learning framework for predicting fracture load and crack initiation angles by directly utilizing stress, strain, or displacement distributions represented by selected nodes as input features. Validation is conducted using experimental data across various mode mixities and specimen geometries for brittle materials. Among stress, strain, and displacement fields, it is shown that the stress-based features, when paired with Multilayer Perceptron models, achieve high predictive accuracy with R2 scores exceeding 0.86 for fracture load predictions and 0.94 for angle predictions. A comparison with the Theory of Critical Distances (Generalized Maximum Tangential Stress) demonstrates the high accuracy of the framework. Furthermore, the impact of input parameter selections is studied, and it is demonstrated that advanced feature selection algorithms enable the framework to handle different ranges and densities of the representing field. The framework’s performance was further validated for datasets with a limited number of data points and restricted mode mixities, where it maintained high accuracy. The proposed framework is computationally efficient and practical, and it operates without any supplementary post-processing steps, such as stress intensity factor calculations.Engineering Fracture Mechanic
Installation effects of supersonic inlets on next-generation SST turbofan engines
Get PDFThis study explores inlet-related installation effects on next-generation SST aircraft, focusing on supersonic business jets. Using a comprehensive framework with consistent thrust/drag bookkeeping and realistic modeling of inlet losses, including operational limits for “buzz” and distortions, the inlet drag accounts for 8.8% to 14.2% of the installed net thrust during the supersonic segment of the mission. Variable airflow control technology is assessed, with a scheduling methodology developed to optimize the inlet operation by minimizing the installed SFC. The results show that this technology improves the installed SFC by 0.80% during supersonic cruise, enhancing the overall propulsion system performance.This research was funded by the SENECA project under the European Union’s Horizon 2020 research and innovation program, grant agreement No. 101006742.14th EASN International ConferenceEngineering Proceeding
On the role of crystal-liquid interfacial energy in determining scaling, nucleation and crystal growth in membrane distillation crystallisation
Get PDFWhile the interfacial energy (σ) of a solute contributes toward the excess surface free energy requirement for nucleation, its role in determining scaling, nucleation and crystal growth processes within membrane distillation has yet to be described. Highly soluble salts (low σ) are generally understood to possess a low nucleation energy, where the limited relative supersaturation (Δc/c∗) can favour a heterogeneous primary nucleation mechanism. This was indicated by scaling, which is generally presumed to occur in response to the membrane substrate lowering the critical Gibbs free energy requirement for nucleation (ΔG∗). For less soluble salts (high σ), primary nucleation was not observed until Δc/c∗ exceeded a threshold of 1. It was postulated that the excess chemical potential available was sufficient to favour homogeneous primary nucleation in the bulk solution, which mitigates scale formation on the membrane. In-situ characterisation methods also established how nucleation rate and crystal size could be directly attributed to the σ, which is compatible with the crystallisation literature on aqueous salts within a comparable range of solubilities. While crystallisation tends to be controlled by a combination of thermodynamic and kinetic processes, this study illustrates how interfacial energy (a thermodynamic quantity) can be used to anticipate nucleation and crystal growth mechanisms in membrane crystallisation.This research was financially supported through European Research Council Starting Grant, ‘Sustainable chemical alternatives for reuse in the circular economy’ (StG, SCARCE, 714080).Journal of Membrane Scienc
Atmospheric pressure plasma etching of Ti-6Al-4 V using SF6 etchant
No full textAtmospheric pressure plasma (APP) etching has been developed recently into a manufacturing technique for silicon-based materials used for large optical lenses. However, there are few reports published regarding APP etching of non-silicon-based materials. We report here the development of an APP process using SF6 for the etching of Ti-6Al-4 V metal alloy. Ti-6Al-4V is extensively used in aerospace and biomedical fields for its excellent properties; however, these properties also make it difficult to machine. Current techniques such as precision grinding and laser polishing can be slow, energy intensive, and cause damages and defects which reduce the lifetime of vital components. The results in this paper demonstrate effective material removal and little surface damage by APP etching of Ti-6Al-4V. Material removal rates between 0.5 and 2 mm3 min−1 were obtained, and the proposed material removal mechanism is through the formation of volatile VFx and TiF4. These results show that APP etching is a promising technique for surface finishing of Ti-6Al-4V, particularly for large- and complex-shaped components.This work was supported by EPSRC Centre for Doctoral Training in Ultra Precision (Grant no. EP/L016567/1) and the Manufacturing Technology Centre Ltd.Journal of Materials Science: Materials in Engineerin
A review of flexible fluid-structure interactions in the ocean: progress, challenges, and future directions
No full textFlexible Fluid-Structure Interaction (FFSI) has emerged as an important, but challenging research direction in modern ocean engineering. This line of research gradually evolved in response to the pressing need to model the dynamic responses of ships and marine structures to sea loads; to predict the performance of flexible marine propellers, energy converters, and coastal protection systems; and to understand the mutual interactions between sea ice, marine vegetation, and mud with oceanic and coastal processes occurring near the surface and seabed. This review presents the state of knowledge and art of modelling of FFSI in the maritime environment, tracing research progress from early physical tests to high-fidelity computational ones emerged recently. Flexible wave–structure interaction, global ship hydroelasticity, hydroelastic slamming, flexible marine propellers, vegetation dynamics, and wave–mud interactions are covered. Limitations and strengths of existing models, and the challenges that remain are discussed in-depth, and it is concluded that FFSI-based research in ocean engineering has very well grown, though some gaps are still open. In specific, hydroelastic effects are still overlooked in the design practices and classification rules do not fully incorporate them, and there are still concerns regarding uncertainties related to FFSI modelling of flexible slamming, dynamic of flexible marine vegetation, and wave-mud interactions. Hence, future research must bridge computational modelling with real-world applications, expand benchmarking coverage for marine engineering problem, and incorporate AI-based methods for modelling FFSI problems, predicting related dynamic responses, or accelerating simulations.Ocean Engineerin
Radiocarbon dating insect samples: new data and recommendations
No full textRadiocarbon dating insects is difficult because insects are small, fragile, and rarely found in sufficient quantities. Interactions between the chitin in the insect body and sources of carbon contamination are less well understood than for collagen and cellulose-based organic materials such as bone and plant remains. Thus there is as yet no single radiocarbon pretreatment that reliably removes all contaminating carbon across all types of insect remains. Various studies have highlighted important information concerning the practicalities and applicability of different approaches to radiocarbon dating insect remains. However, there are no papers that synthesise findings across different studies. Here, we present a review of previous work alongside new data to investigate different chemical approaches to sample processing and long-term storage and their impact on the chemistry of samples and contaminants. This confirms the difficulty of removing contamination from older samples while retaining sufficient pretreated material for subsequent measurement. It also shows that Fourier transform infrared (FTIR) spectroscopy does not always provide sufficient resolution to detect carbon contamination from non-insect sources with confidence. Thus, insect samples that have been in contact with paraffin or stored in ethanol for an extended period of time should not be selected for radiocarbon dating.Environmental Archaeolog
Deglobalization and the rehabilitation of Western defense industrial sovereignty
No full textIn recent years, global security has been disrupted by a series of “unknown unknown” events, such as COVID-19, Russia’s invasion of Ukraine, and the Palestinian crisis. These challenges have led Western nations to weigh the strategic risks of defense industry vulnerabilities against the economic benefits of globalization. As a result, the U.S., Australia, the EU, and the UK have launched strategies focused on bolstering defense industrial sovereignty. This paper examines the common themes and relative strengths of these strategies.Comparative Strateg
Techno-Economic Environmental Risk Analysis (TERA) in hydrogen farms
No full textThis study presents a techno-economic environmental risk analysis (TERA) of large-scale green hydrogen production using Alkaline Water Electrolysis (AWE) and Proton Exchange Membrane (PEM) systems. The analysis integrates commercial data, market insights, and academic forecasts to capture variability in capital expenditure (CAPEX), efficiency, electricity cost, and capacity factor. Using Libya as a case study, 81 scenarios were modelled for each technology to assess financial and operational trade-offs. For AWE, CAPEX is projected between 905.6 billion for 519 GW (gigawatts) of installed capacity, equivalent to 600–1745 612 billion to /kW. Results indicate that AWE, while requiring greater land use, provides significant cost advantages due to lower capital intensity and scalability. In contrast, PEM systems offer compact design and operational flexibility but at substantially higher costs. The five most economical scenarios for both technologies consistently feature low CAPEX and high efficiency, while sensitivity analyses confirm these two parameters as the dominant cost drivers. The findings emphasise that technology choice should reflect context-specific priorities such as land availability, budget, and performance needs. This study provides actionable guidance for policymakers and investors developing cost-effective hydrogen infrastructure in emerging green energy markets.Energie
Peanut value chain development: the case of Lower Lake Victoria Basin of Kenya
No full textThis article belongs to the Collection Agricultural and Natural Resource EconomicsPeanut is Kenya’s second most important legume after beans, primarily grown in the Nyanza and Western regions. This study maps the peanut value chain in Kenya, aiming to identify key actors, quantify costs and value addition, and outline constraints and opportunities, with a view to upgrading the chain. A cross-sectional survey was conducted among value chain actors in Karachuonyo and Nyakach sub-counties, complemented by secondary data sources. Descriptive statistics were used to analyze socio-economic characteristics, production volumes, pricing, demand trends, and policy-related factors. The findings indicate a predominance of female farmers (68%) in peanut production, though few use improved technologies; only 26% were aware of improved seed varieties, and just 1.5% reported using them. Fertilizer usage was absent, attributed to high costs, soil conditions, and limited knowledge. The wholesale and processing segments are male-dominated, largely due to capital intensity and travel requirements, while female traders dominate the retail sector. Strengths Weaknesses Opportunity and Threats (SWOT) analysis highlighted the significant potential of favorable production ecologies, processing options, and robust demand in local and international markets. Key constraints identified include limited seed availability, high fertilizer costs, pest issues, and declining soil fertility. Policy implications include increasing access to affordable inputs, promoting gender-inclusive programs, investing in agricultural research and infrastructure, supporting sustainable farming practices, and fostering public-private partnerships to expand processing and market access.This research was funded by the EU H2020 EWA-BELT project [862848] “Linking East and West African farming systems experience into a BELT of sustainable intensification” coordinated by the Desertification Research Centre of the University of Sassari.Economie
Mentoring early career researchers
No full textThe Curious Future Insight Conference is a platform that brings together scientists from around the world every 2–4 years to discuss the latest advances and innovations in science and technology with the aim of ‘uniting through science for a better tomorrow’. Over the 2-day gathering, a number of themes are covered relating to Energy, Healthy Lives, the Human Mind, Life Reimagined, Materials & Solutions, Nutrition and Vibrant Digital. In the 2024 conference, the importance of mentoring and supporting Early Career Researchers within the wider science ecosystem was a prominent feature of a panel session hosted by AAAS/Science and moderated by Dr. Rachel Bernstein of Science, deputy news editor focusing on careers and community. In this panel session that also included Dr. Senka Holzer, Medical University of Graz and Professor Ulrike Fasbender, University of Hohenheim in Germany, we explored the importance of the mentor/mentee relationship from a scientific and professional perspective, how the relationship can help individuals in navigating challenges within a science career and strategies and approaches for fostering the relationship. This chapter will address some of these main themes around mentoring relationships, bringing in our insights and personal perspectives.Science for a Better Tomorrow: Curious 2024 Insight