82984 research outputs found
Sort by
Experimental and machine learning study on the influence of nanoparticle size and pulsating flow on heat transfer performance in nanofluid-jet impingement cooling
Full text linkDATA AVAILABILITY :
Data will be made available on request.Maximizing heat transfer efficiency is crucial for enhancing performance and durability in diverse engineering applications, including fuel cells, EV batteries, and solar PV/T systems, thereby advancing sustainable energy innovation. This study investigates thermal dissipation from a simulated heat sink aligned with a PV cell’s back plate via jet impingement cooling. Specifically, it examines the impacts of pulsatile cooling and nanoparticle size in hybrid nanofluids, comprising combinations of Al2O3 and MWCNT in water, with varied nanofluid volume fraction (0.05 vol% ≤ ɸ ≤ 0.3 vol%) and flow Reynolds number (15000 < Re < 40000). Key findings reveal significant influences of nanoparticle size, nanofluid concentration, and pulsating flow on heat transfer performance. Notably, sample D demonstrated the highest heat transfer enhancement, achieving approximately 52.94 % and 79.06 % improvement in continuous and pulsating jet cooling compared to de-ionized water under continuous jet cooling. Machine learning classifiers were employed to identify critical thermal performance parameters, with Reynolds number identified as the most significant factor influencing heat transfer. Random Forest and Gradient Boosting classifiers showed notable accuracy in predicting Nu, emphasizing the role of machine learning techniques in optimizing thermal management strategies for improved heat dissipation from solar PV cell backplates.https://www.elsevier.com/locate/apthermenghj2024Mechanical and Aeronautical EngineeringSDG-09: Industry, innovation and infrastructur
Otolith shape analysis as a tool for species identification and management of cryptic congeners in the northern Benguela ocean warming hotspot
No full textDATA AVAILABILITY :
A link to all data is included in the manuscript.Adaptive management is critical to maintaining resilient fisheries in our rapidly changing ocean environments. However, establishing appropriate and cost-effective monitoring programmes that adequately capture the responses of fisheries to climate change have been elusive. The coastal waters of central and northern Namibia are a global hotspot of ocean warming, with several responses by fish impacting its coastal fisheries. One documented change is a poleward distributional shift of the west coast dusky kob, Argyrosomus coronus into Namibia, where it has begun to hybridize with the congeneric A. inodorus. With considerably different life histories, it is critical that managers can differentiate between these species and the hybrids to appropriately manage the most important recreational and commercial linefish species (bycatch and biomass) in Namibia. In this paper, we used otolith shape analysis, Linear Discriminant Analyses (LDA) to show that otolith shape can be used to distinguish between species and their putative hybrids, identified based on mitochondrial DNA and nuclear microsatellite data. A total of 342 individuals from northern and central Namibia (northern Benguela) between 18.5 and 22.7°S were genetically identified, with a subsample of 217 paired with otolith shape analysis. Otolith shape analyses with LDA and leave-one-out cross validation showed successful species identification at 96.3 % accuracy, and improved accuracy of hybrid identification compared to using body morphology by 50 %. The Fourier descriptors provided excellent classification accuracy for separating A. coronus from A. inodorus (and putative hybrids, but poorer classification accuracy for separating the hybrids from A. inodorus (4/8). We thus recommend using otolith shape analysis for distinguishing the two species but suggest that genetic identification is still required to monitor hybridization. Monitoring for adaptive management should therefore include routine otolith collection and species classification to improve stock assessment and promote the development of appropriate management strategies for this important fishery in the northern Benguela.The Ministry of Fisheries and Marine Resources, Namibia; Department of Fisheries and Ocean Sciences, University of Namibia; the Department of Ichthyology and Fisheries Sciences, Rhodes University, South Africa; the Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, UK; the Marine Genomics Group, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, South Africa; UKRI Global Challenges Research Fund One Ocean Hub - flexible fund and Wild Skeleton Coast Adventure Tours.http://www.elsevier.com/locate/fishres2025-12-30hj2024Biochemistry, Genetics and Microbiology (BGM)SDG-14:Life below wate
Establishing the erga omnes character of the obligation to prevent transboundary environmental harm
Full text linkThis article argues that the obligation to prevent transboundary environmental harm is erga omnes. In a fractured landscape, this obligation is the closest that international environmental law comes to a general obligation to protect the environment and should its erga omnes character be established, all States will be able to act when it is breached. In the absence of a settled methodology for identifying erga omnes obligations and using methodologies put forward in the literature and the characteristics of the erga omnes concept, this article argues that four criteria need to be met for an obligation to be erga omnes, namely that the obligation (i) has an agreed upon customary content, that it protects a (ii) common and (iii) essential interest, and (iv) that the ‘international community as a whole’ is the ultimate beneficiary. Using these criteria, the article is able to establish the erga omnes character of the obligation to prevent transboundary environmental harm.The National Research Foundation of South Africa.https://brill.com/view/journals/mpyo/mpyo-overview.xml?language=enhj2024Public LawSDG-16:Peace,justice and strong institution
Studying transfers in informal transport networks using volunteered GPS data
Full text linkMultimodal integration is an important issue in public transport systems due to its influence on both passenger experience and overall network efficiency. In most countries in the global South, achieving integration is particularly problematic because of the informal nature of most public transport. Decentralised service planning and demand responsiveness lead to often uncoordinated, highly variable service patterns, which are not optimised from a passenger perspective. Efforts to promote integration are also hampered by a lack of planning data on routes, service frequencies, and transfer locations. This research asks whether GPS data supplied by passengers as they move through the network can be used to help form a better understanding of the extent and quality of the transfer experience. The data was collected in the City of Tshwane, South Africa, among informal minibus-taxi passengers. Post-processing involved the use of a machine learning algorithm to identify in-vehicle, wait and walk segments, which were used to identify transfers between one vehicle and another. The results showed that many transfers are spatially efficient with short walk and wait times, but that a minority of transferring passengers may experience very long transfers. Transfers encompass a diverse range of behaviours including pacing, shopping and browsing, and typically involve much more walking than waiting. Transfers also occur across a wide range of locations, but tend to be concentrated in certain nodes and along street segments. Strategies to improve transfer facilities as well as general walkability might be targeted at such locations. The study demonstrated that volunteered GPS data is a promising source of information to help planners understand the transfer experience in multimodal networks in data-poor environments.The Centre for Transport Development at the University of Pretoria and partial support from the Mastercard Foundation Scholarship Programme at the University of Pretoria.https://www.elsevier.com/locate/tbshj2024Civil EngineeringSDG-09: Industry, innovation and infrastructureSDG-11:Sustainable cities and communitie
Developing an inclusive African theory of academic literacy
Full text linkSouth Africa has enjoyed post-apartheid democratic freedom for thirty years. However, three
decades after apartheid’s legal end, institutions of higher learning still grapple with a significant crisis of
student attrition. Approximately 25% of South African students drop out annually without completing their
degree or academic year. According to the current article, this high dropout rate is partly attributed to a
lack of a coherent theory of academic literacy, which could mitigate the feelings of alienation experienced
by African students. This article argues that the dependence of African universities on Global North
constructs of academic literacy limits students’ experiences of inclusion and belonging to specialized
disciplinary domains. To address the crisis of student attrition, as well as experiences of cultural alienation
in universities where African students are enrolled, this article proposes developing an African Theory of
Academic Literacy (ATAL). The objective of this theory is to empower academic literacy educators to ground
their teaching, learning, and assessment practices in an Afrocentric paradigm, thereby fostering a stronger
sense of inclusion among novice scholars within their disciplines.https://cgscholar.com/bookstore/cgrn/242/250Unit for Academic LiteracySDG-04:Quality Educatio
Effects of semiochemical pre-feeding, physiological state, and weather on the response of Bactrocera dorsalis to methyl eugenol baited traps
Full text linkDATA AVAILABILITY :
Data for this study are openly available in figshare at 10.25403/UPresearchdata.25880326.v1, reference number 25880326.v1.Plant-derived phenylpropanoids are semiochemicals that are often highly attractive to Bactrocera (Diptera: Tephritidae) males. One of these semiochemicals, methyl eugenol (ME), is used in the male annihilation technique (MAT) for the management of B. dorsalis (Hendel), a destructive horticultural pest. It is not normally viable to simultaneously implement MAT with the sterile insect technique (SIT), as released sterile males are attracted to MAT devices. However, prior semiochemical exposure can reduce the later response of Bactrocera males to the same or another semiochemical, which may allow the synchronous application of MAT and SIT. We determined how the interaction between semiochemical pre-feeding, weather, and fly physiology impacted the response of male B. dorsalis to ME baited traps. Response by a known number of males in field cages was determined in relation to temperature, relative humidity, semiochemical pre-feeding (ME, eugenol, or none), diet (protein supplemented and protein deprived) and age (4, 10 and 20 days old). Semiochemical pre-feeding of both ME and eugenol equally decreased the response of males that were 10 days old, or older, to ME baited traps. Adult diet had no effect on the response of males to ME baited traps. Response improved as temperature and relative humidity increased. These results highlight the feasibility of synchronous MAT-SIT programmes targeting B. dorsalis and the viability of continued protein supplementation of sterile males. We show that eugenol is an alternative to ME for suppression of male B. dorsalis response to MAT devices and that weather conditions significantly affect the variability and reliability of abundance estimates from trap captures.The International Atomic Energy Agency and a Citrus Academy bursary.https://www.elsevier.com/locate/croprohj2024Forestry and Agricultural Biotechnology Institute (FABI)Zoology and EntomologySDG-02:Zero Hunge
Policing the police : why it is so hard to reform police departments in the United States?
Full text linkWhy has it been so difficult to reform U.S. policing? We provide a theoretical argument that understanding of the entrenched militarisation and accountability problems of U.S. police departments would benefit from using theory in comparative research on civil–military relations. American police forces undermine local democracy by encroaching upon the decision-making powers of city officials in ways that resemble militaries in fragile democracies. Applying historical and contemporary evidence and existing scholarly research on policing, we explain police militarisation was initiated by civilian leaders of city governments to garner governmental legitimacy, and by-proxy police support, in racialised contexts. Trading off city governments’ institutional strength in order to maintain legitimacy produced opportunities for police insubordination or subversion of city government oversight of police activity. Consequently, cities with low public legitimacy and/or weak municipal institutions, faced with high demands by militarised police departments, may be more likely to experience police subversion of democratic accountability over police activity.https://journals.sagepub.com/home/BPIhj2024SociologySDG-16:Peace,justice and strong institution
Organic ligands and CeO2-induced generic valence modulation strategies to design Fe active sites for promoted oxygen involved reactions in rechargeable zinc-air batteries
No full textDATA AVAILABILITY : The authors declare that all data supporting the findings of this study are available within the paper and its ESI.Please read abstract in the article.The Open Project Program of the Guangdong Provincial Key Laboratory for Electronic Functional Materials and Devices at Huizhou University and the Natural Science Foundation of Shandong Province, China.https://pubs.rsc.org/en/journals/journal/ta2026-02-03hj2024Chemical EngineeringSDG-07:Affordable and clean energ
Revealing factors influencing digital transformation in South Africa's social security organisations
Full text linkDATA AVAILABILITY STATEMENT : The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.The study analyses factors influencing digital transformation in South Africa's national social security organisations. Data were collected through semi-structured interviews with 20 purposefully selected respondents and analysed using thematic analysis. The study found seven factors influencing digital transformation in South Africa's national social security organisations: Legal authority, Policy autonomy, Human resources, Finance, digital data collection and use, digital infrastructure and applications and digital skills and collaborative work. The study's findings showed that digitalisation per se does not lead to a better balance between policy alignment and organisational autonomy. On the contrary, the unprecedented access to ubiquitous data and massive processing capacity can heighten the tendencies of rigid systems for greater hierarchical control and lead to a future where decision-making is further centralised, data are inaccessible, the staff is disempowered and innovation is stifled. However, the study also highlights a potential solution—the need for hierarchical leaders to transition into collaborative workspace enablers who enhance the agencies' operational capabilities. This shift in leadership style can inspire innovation and empower staff, thereby mitigating the negative effects of digitalisation.https://onlinelibrary.wiley.com/journal/14791854hj2024School of Public Management and Administration (SPMA)SDG-17:Partnerships for the goal
Transforming academic literacy : centering indigenous identities in the classroom
Full text linkThis article explores the transformational potential of centering indigenous identities and heritage within academic literacy instruction in higher education. The dominance of Eurocentric pedagogies in higher education has often marginalized African epistemologies and cultural narratives, limiting students’ engagement and sense of be-longing. Drawing on examples such as the Ma’at and Tewahedo traditions, this work argues that academic literacy should embrace Indigenous Knowledge Systems and the cultural capital students bring to the classroom. By integrating indigenous identities into disciplinary discourses, educators can create more inclusive learning environments that challenge historical power dynamics and elevate marginalized voices. This analysis high-lights practical strategies for educators to foster critical thinking, reading, and writing while affirming students’ identities. Ultimately, this article demonstrates that activating Indigenous Knowledge Systems can create classrooms that are inclusive and reflective of African identities.https://www.mdpi.com/journal/genealogyUnit for Academic LiteracySDG-04:Quality Educatio