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Numerical Simulation Study on the Drag Reduction Characteristics of Grooves-Microbubbles Coupling Surfaces
Get PDFSurface drag reduction technologies can significantly reduce the resistance during ship navigation, enhancing speed, efficiency and adaptability under various operating conditions. This paper uses numerical simulation technology to analyze the drag reduction characteristics of grooved and grooves-microbubbles coupling surface, focusing on the effects of groove width, gas flow rate, and liquid flow velocity on the drag reduction performance. The research results indicate that the grooved surface is suitable for full surface drag reduction at velocity below 3 m/s with a maximum drag reduction rate of 4.02%. Microbubbles can greatly improve the drag reduction effect of the grooved surface, and the drag reduction effect of the coupling surface gradually increases with the gas flow rate increases. The maximum drag reduction rate can reach 89.86% at the gas inlet velocity of 1 m/s. The liquid flow velocity has a significant impact on the drag reduction. In both the groove model and the coupling model, the drag reduction rate initially rises and then declines with the liquid flow velocity increases
Special issue: Cultivating character for care
Get PDFIn October 2022, a group of scholars and practitioners came together to discuss some of the most challenging questions relating to ethical care practices. The theme of the symposium was Cultivating Character for Care. The context for the event was a post-pandemic ecology of care which increasingly symbolised care as in ‘crisis’. Challenges in care, regularly reported in the media and in everyday conversations, related to the escalating need for care due to demographic changes; to problems with staff recruitment, retention and professionalism; to under-resourced and overwhelmed health and social care services; and to the impact of climate change. Symposium participants came from a range of disciplinary and professional backgrounds and had lived experiences of engaging with health and social care provision
'We’re not that Gullible!’ — Revealing Dark Pattern Mental Models of 11-12 Year-Old Scottish Children
Get PDFFor the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.Deceptive techniques known as dark patterns specifically target online users. Children are particularly vulnerable as they might lack the skills to recognise and resist these deceptive attempts. To be effective, interventions to forewarn and forearm should build on a comprehensive understanding of children’s existing mental models. To this end, we carried out a study with 11- to 12-year-old Scottish children to reveal their mental models of dark patterns. They were acutely aware of online deception, referring to deployers as being ‘up to no good.’ Yet, they were overly vigilant and construed worst-case outcomes, with even a benign warning triggering suspicion. We recommend that rather than focusing on specific instances of dark patterns in awareness raising, interventions should prioritise improving children’s understanding of the characteristics of, and the motivations behind, deceptive online techniques. By so doing, we can help them to develop a more robust defence against these deceptive practices.SPRITE (EP/S035869/1); REPHRAIN (EP/W032473/1
Impact of RON on a heavily downsized boosted SI engine using 2nd generation biofuel – A comprehensive experimental analysis
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Data will be made available on request.Sustainable energy solutions are paramount in the urgent global drive against climate change, especially in transportation. This research focuses on second-generation biogasolines and their potential in the context of decarbonisation. Two biogasolines, 99 RON E20 and 95 RON E20, were rigorously tested in a downsized single-cylinder engine. Their performance, combustion, and emissions were compared against the conventional fossil fuel, 95 RON E10, under varying engine loads. Additionally, a comprehensive injection parameter sweep was conducted for both biofuels at low and high loads, shedding light on their unique operational characteristics and operational regimes. This research significantly enhances our knowledge about the potential of these new biofuels and their implications for a more sustainable energy future. The findings of the experiments demonstrate no substantial difference between the tested biofuels and fossil fuels. Biofuel with a higher octane number provides more knock resistance than fossil fuel, resulting in increased thermal efficiency due to spark advance ability. However, more significant hydrocarbon emissions were detected for biofuels than fossil fuels due to more extensive aromatic content. Both biofuels have stable combustion in low and high-load operations under varying injection pressures and injection start times. 99 Bio E20 has a wider operational range than 95 Bio E20. However, due to very high HC emissions, especially at high-load operations, an early injection start with more significant injection pressure is not recommended for biofuel. From a broader perspective, both biofuels exhibit the promising potential to serve as drop-in replacements in spark ignition engines
Enhanced groundwater availability through rainwater harvesting and managed aquifer recharge in arid regions
Get PDFClimate change in desert areas and semi-arid watersheds may offer a promising solution for the water scarcity problem that Bedouins and local inhabitants face. This study investigated the integrated water resources management in arid and semi-arid regions using rainwater harvesting in combination with the managed aquifer recharge (RWH-MAR) technique. The study also used recharge wells and storage dams to achieve the sustainability of groundwater supplies in the context of climate change and management of the flow to the Gulf of Suez. Therefore, different return periods of 10, 25, 50, and 100 years were considered for the annual flood volume resulting from those watersheds. Moreover, hydrologic modeling was carried out for the El Qaa plain area, South Sinai, Egypt, using the Watershed Modeling System (WMS) and the groundwater modeling of SEAWAT code. Our findings show that for different scenarios of climate change based on return periods of 10, 25, 50, and 100 years, the aquifer potentiality reached 24.3 MCM (million cubic meters) per year, 28.8 MCM, 36.7 MCM, and 49.4 MCM compared to 21.7 MCM at 2014 with storage of groundwater ranges 11.8%, 32.1%, 69%, and 127.4%, respectively. These findings have significant implications for the system of RWH-MAR and groundwater sustainability in El Qaa Plain, South Sinai. The RWH-MAR proved to be an effective approach that can be applied in different water-stressed and arid regions to support freshwater resources for sustainable future development and food security, as well as protect communities from extreme flash flood events.The author(s) received no specific funding for this work. Alban Kuriqi is grateful for the Foundation for Science and Technology's help through funding UIDB/04625/2020 from the research unit CERIS
A literature and practice review to develop archetypes of upstream packaging strategies for a circular economy
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No data was used for the research described in the article.Plastic pollution is a serious issue of global concern which requires an urgent and international response involving all relevant actors at different levels of the supply chain. Increasing production of single use plastics and the mismanagement of the resulting plastic packaging waste is one of the prominent reasons for this pressing environmental issue. Several potentially promising solutions, such as reusable, recyclable and compostable packaging systems exist. Many of these innovative approaches may contribute to achieving a circular plastic economy, but there is a need to categorise and collate these under unifying themes to facilitate the assessment and comparison of different strategies.
The aim of this research is to analyse and categorise the existing solutions that tackle the plastic packaging waste problem to identify the archetypes of these solutions. Literature and business practice reviews were conducted to discover existing solutions. 200 solutions were selected and categorised by exploring the common patterns. Finally, 10 archetypes and 17 sub-archetypes were introduced. These archetypes are: refill stations, mobile refill stations, refill at home solutions, prefilled packaging systems, reusable takeaway and delivery solutions, B2B reusable packages, packaging solutions led by elimination, compostable and biodegradable packaging, substitution to a non-plastic material and plastic recycling. The findings led to the development of an upstream packaging strategies framework. This paper makes an original contribution to knowledge with the development of this framework as a systematic way to map existing (and new) solutions that can potentially tackle the plastic packaging waste and pollution problem.PISCES project funded by NERC grant (NE/V006428/1)
London, you have a problem with women: Trust towards the police in England
Get PDFFollowing a series of high-profile incidents of violence against women by serving London Metropolitan Police Officers, questions of standards and the public’s confidence in policing are in the spotlight. Over a fifteen-month period between July 2022 and September 2023 using monthly surveys of representative English samples, this study confirms that women, in general, are more trusting in the police than men. This, however, does not hold true in London. Out of nine regions in England, London is the only region where women’s overall trust in the police is lower than men. Lower levels of trust in the police among women in London hold when controls for age, income, political environment and crime levels are considered. In line with existing literature that considers women being more sensitive to cues about trustworthiness, the concerning incidents of sexual violence by police officers against women are likely to further erode trust in police in the capital, which already ranks last among England’s nine regions in citizen trust of the police.Japan Society for the Promotion of Science (JPJSJRP 20211704 ); UK Research and Innovation (ES/W011913/1)
Editorial: Gastropoda immunity and host-pathogen interactions
Get PDFThis Research Topic on gastropod innate defense is a timely and important contribution toward filling an existing information gap on a topic that covers a large taxonomic class within the phylum mollusca. Gastropods, commonly known as snails and slugs are numerous, diverse, and widespread in environments ranging from freshwater to dry land. Their survival throughout millennia is a testament to an ability to adapt and thrive by possessing an innate defense system that we still do not completely understand. ...The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article
Persistence in European Stock Market Returns and Volatility
Get PDFThis paper applies fractional integration techniques to analyze persistence in stock market returns and volatility at different frequencies in the case of various European indices, specifically the French CAC, the Spanish IBEX 35, the German DAX, the British FTSE 100, and the Euro Stoxx 50, over the period from January 2018 to January 2023.Returns are calculated as the first differences of the logged prices, while absolute and squared returns are used as volatility proxies. The method used yields estimates of the differencing parameter d, which is allowed to take any real value, including fractional ones, and represents a measure of persistence. This parameter provides information about whether the series of interest exhibit either long memory or mean reversion. Specifically, a value of d greater than 0 indicates the presence of long memory in the series, while a value less than 1 implies mean reversion, with the effects of shocks being transitory. The results vary depending on the data frequency. More precisely, evidence of long memory is found for returns at the daily frequency only and for volatility proxies at both the weekly and daily frequencies but not at the monthly frequency. In most cases our findings imply that stock prices are I(1) and thus follow a random walk, which is consistent with the efficiency markets hypothesis (EMH)
New laminar flame speed correlation for lean mixtures of hydrogen combustion with water addition under high pressure conditions
Get PDFHydrogen may become a substitute for liquid fossil fuels, contributing to greenhouse gas emissions reductions in internal combustion engines. Numerical simulations play a critical role in the advancement of these engines, with laminar flame speed being the main input. Experimental data of hydrogen flame speed at elevated pressures are scarce, due to the instability of the flames. Nonetheless, stable hydrogen flames can be predicted using chemical kinetics models. Moreover, the injection of water into the hydrogen fuelled engine could offer several benefits to engine combustion and emission performance, as it modulates the laminar flame speed within the combustion chamber and this effect has not been completely understood. Currently, no correlation exists to predict the laminar flame speed of hydrogen-air combustion with water addition under lean mixture engine operating conditions. In this study, we have extended the newly developed laminar flame speed correlation of hydrogen-air combustion to account for the effects of water addition under engine relevant conditions by using chemical kinetic laminar flame speed values. The laminar flame speed correlation was derived for pressures from 10 to 70 bar, temperatures from 400 to 800 K, equivalence ratios from 0.35 to 1 and water addition by mole from 0 to 20%. The hydrogen laminar flame speed correlation was expressed using polynomial forms with reduced order and number of terms with optimized values of coefficients. Additionally, a new exponential term was proposed to the power term α of the laminar flame speed correlation to capture the coupled effects of pressure and temperature on laminar flame speeds under engine-relevant lean burn water-diluted operating conditions
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