159370 research outputs found
Sort by
Sustainable cobalt leaching using in-situ CoO reduction: a microwave-driven solution for complex ores
Get PDFThis study presents a green cobalt extraction method from Zebesha ore in Zambia, combining carbothermic reduction with microwave-assisted leaching (MWL) and conventional leaching (CL). Ore mixed with 20 wt.% charcoal was roasted at 650 °C for 1.5 h in air, reducing Co₂O₃·H₂O to CoO. A 1:1 mixture of roasted and unroasted ore was leached under MWL and CL conditions. The CoO in the roasted portion served as an in-situ reductant, converting Co3⁺ to Co2⁺ in the unroasted ore. MWL achieved 98.0% cobalt extraction in 30 min, compared to 96.5% in 180 min for CL. This method eliminates sodium metabisulphite, avoiding harmful sodium sulphate byproducts. The approach provides a sustainable, low-energy route for cobalt recovery from both primary ores and secondary resources such as spent lithium-ion batteries
News and surprises: Revisiting fiscal shocks in the open economy
No full textDespite extensive research on fiscal policy, evidence on the international transmission of structural fiscal shocks remains limited and inconclusive. We address three gaps. First, we confront the perfect-foresight problem by incorporating a proxy for fiscal policy news into a multi-country VAR model—to our knowledge, the first such study to use this proxy to measure cross-border transmission of US fiscal shocks in a detailed setting. Second, we estimate a Bayesian multi-country VAR that, unlike two-country approaches, fully captures higher-order spillovers. Third, we revisit the interpretation of fiscal multipliers from New Keynesian closed-economy models. We find: (i) international spillovers operate mainly through trade (expenditure switching and boosting); (ii) transmission hinges on each recipient’s growth model; (iii) higher-order spillovers substantially amplify direct spillovers; and (iv) the exchange rate puzzle reflects omitted variables and policy regime effects
A novel analytical approach for evaluating thermally active underground retaining walls
Get PDFShallow geothermal energy is a promising renewable technology for sustainable indoor heating and cooling. One method to exploit this energy is through Energy Geostructures, where structural elements embedded in the ground are thermally activated via heat exchange pipes embedded within the structure. These structures function as a specialised form of ground heat exchanger, which can be integrated with ground source heat pump systems. Energy walls (EWs), a specific type of Energy Geostructure, are commonly used in basements, underground parking facilities, and metro stations. Despite their potential, there is currently no simple and reliable analytical method for the thermal analysis of EWs. Instead, their design relies on computationally expensive numerical simulations or oversimplified 'rules of thumb', both of which may lead to inefficiencies in cost and performance. This study presents a novel analytical approach based on the Infinite Plane Source (IPS) model and evaluates its accuracy by comparing it with two-dimensional numerical model data. The results demonstrate that the proposed method provides highly accurate estimates of temperatures at the back of the wall, making it a valuable foundation for future analytical design methodologies. The findings are applicable to EWs having an excavation on one side and ground on the other, as well as fully buried EWs with soil on both sides. This research offers a significant step toward the development of a practical, cost-effective analytical framework for the design and optimisation of EWs, promoting the broader adoption of shallow geothermal energy systems
Measurements of differential cross-sections of WbWb production in the dilepton channel in pp collisions at √s = 13 TeV using the ATLAS detector
Get PDFAt the Large Hadron Collider, the W bW b final state is expected to be dominated
by tt¯ production with a contribution from single-top processes. Differential cross-sections
for W bW b production in the dilepton decay channel are measured at the particle level as a
function of various kinematic variables. The analysis is based on data from proton-proton
collisions at a centre-of-mass energy of √
s = 13 TeV, recorded by the ATLAS detector at the
Large Hadron Collider over the period from 2015 to 2018, corresponding to an integrated
luminosity of 140 fb−1
. Measurements are performed within the fiducial phase-space defined
by the presence of two b-jets and one electron and one muon of opposite charges. The
differential cross-sections are corrected for detector effects and unfolded to the particle level.
Results are compared with predictions from Monte Carlo event generators at next-to-leading
order in perturbative quantum chromodynamics; overall the measurements are in reasonable
agreement with several generator setups, although no single prediction is able to describe
all measured distributions simultaneously. These measurements provide valuable constraints
on the modelling of W bW b production and the interference between doubly resonant and
singly resonant W bW b production
Woodland creation scheme in the Yorkshire Dales successfully focuses tree planting on soils with lower soil organic carbon stocks
Get PDF1. Tree planting is a key climate mitigation strategy, but afforestation on organo-mineral soils may cause soil organic carbon (SOC) losses, limiting long-term ecosystem carbon gains over decadal timescales. New woodland creation guidance aims to avoid tree planting on high-carbon soils to protect existing SOC stocks.
2. We measured topsoil SOC stocks (0–15 cm) at a new native woodland in the Yorkshire Dales, UK, with highly variable organo-mineral soils typical of many UK uplands. The woodland design was based on peat depth, vegetation classification, archaeological features and breeding bird surveys.
3. Our study had two aims. First, to test whether the woodland design resulted in tree planting in areas with lowest SOC stocks at a site scale. Second, to assess whether low-disturbance, hand-planting techniques avoided high SOC stocks at plot scale. Five replicate 10 × 10 m plots were established for each of three treatments: unplanted, low-density and high-density tree planting. Each planted plot was paired with a topographically similar unplanted control. Soil cores were sampled randomly across each plot as well as close to planted trees. Fieldwork occurred 9–13 months after planting began.
4. We found SOC stocks were significantly lower in high-density plots (median = 75.60 t C ha−1; IQR = 66.44–87.95) than in unplanted (97.70 t C ha−1; 80.74–115.59) and low-density plots (91.47 t C ha−1; 78.67–99.98; p < 0.05), indicating that areas selected for tree planting preferentially targeted lower carbon soils as planned. No evidence was found to suggest avoidance of higher carbon soils at the 10-m plot scale.
5. Practical implications. Our results show that careful woodland design can avoid tree-planting on high-carbon organo-mineral soils. Our work shows that new woodland creation guidelines in England are likely to reduce the potential for SOC losses by targeting high-density tree planting on soils with lower SOC stocks
Reliability premium: A generic conceptual framework for evaluating the cost of travel time variability
Get PDFIn this paper, we propose the reliability premium as a generic concept that eliminates the utility difference between the expected utility and the utility of a travel choice that is subject to randomness in travel time–without specifying the underpinning utility function nor the travel choice domain to which it relates. Mathematically, the reliability premium quantifies the buffer or additional time a traveller is willing to pay beyond the expected outcome of a travel choice to eliminate the extra disutility due to travel time variability (TTV), thereby conceptualising the cost of TTV directly and intuitively in time units. We then discuss the reliability premium under, first, the Bernoulli approach, which focuses on route choice only, and second, the scheduling delay approach, which encompasses both departure or arrival time choice and route choice. Under the Bernoulli approach, we show that it is convenient to derive the monetary cost of travel time variability based on the reliability premium. In addition, we discuss the preservation of first-order and second-order stochastic dominance (SD) of the reliability premium, which removes the computational concern of using the reliability premium in reliable path-finding problems or related assignment models. Under the schedule delay framework, we derive formulations of the reliability premium for different applications and show the detailed impact of TTV on the resulting valuations. We find that the reliability premium can be effective in capturing the asymmetry and distributional tail of travel times for quantifying the TTV cost, especially for risk-averse users, making it suitable for evaluating the impact of TTV on travellers’ route choice decisions. Numerical examples are employed to elucidate the concept of the reliability premium and illustrate its practical application
Developing a three-level circular economy framework to measure circularity for meso-level assessment in pavement construction
Get PDFThe transport sector significantly contributes to global resource consumption and CO2 emissions, with pavement construction playing a key role. While circular economy principles have been adopted, existing research primarily addresses macro-level policies and micro-level implementations, leaving meso-level assessment underexplored. Establishing an industry-accepted circular economy system for pavement construction is fundamental for improving the overall circularity index and integrating these principles across all dimensions. This study develops a three-level conceptual model to systematically measure circularity in the pavement construction sector. The model is based on an extensive literature review, standards analysis, and discussions with expert panels. Utilizing the spherical fuzzy analytic hierarchy process framework, this approach is applied for the first time in the pavement construction sector to reduce uncertainty and bias. Moreover, the study synthesizes feedback from 11 key stakeholders, including pavement construction companies, consulting firms, and academic experts from multiple countries, to assess the meso-level circularity index. The results reveal a circularity index of 56.9 %, indicating moderate integration of circular economy practices within the industry and highlighting critical areas for improvement. Additionally, the social indicator, despite having a relatively low weight, demonstrates high implementation potential, suggesting that prioritizing it through policy interventions could lead to short-term gains. The meso-level evaluation model bridges the gap between macro-level policies and micro-level implementation, providing decision-makers and companies with actionable insights into the industry's sustainability status. Furthermore, the proposed model integrated with spherical fuzzy analytic hierarchy process offers a valuable reference framework for promoting circular economy practices in other industries
Qualitative Pilot Study of Teachers’ Expectations for Young Students’ Use of Educational Technology
Get PDFMy PhD project explores female Saudi teachers’ expectations regarding classroom use of educational technology by female students aged 6 to 8. This pilot study was conducted to examine the validity and suitability of data collection tools proposed for the main project and to identify issues, limitations, and possible adjustments. A qualitative approach included a narrative interview and two semi-structured interviews with a total of three female teachers plus two classroom observations of a total of 45 young female students, all from two schools. Piloting provided useful feedback about the proposed instruments, enabling refinements for the main study: discontinuing narrative interviews that proved unsuitable, transferring some observation elements to interviews, and adjusting interview questions. Other benefits included exploring specific research environments; improving logistics and coordination; and reflecting critically about enhancing interview-management frameworks, contingency strategies, and interviewing and rapport-building skills, all of which will prove invaluable for the overall research design
Green social prescribing delivered by community organisations supports wellbeing among ethnically diverse communities in England
Get PDFSocial prescribing connects people to community activities and services to meet practical, social and emotional needs affecting their health and wellbeing. Green social prescribing (GSP) focuses on prescribed activities that are nature-based using green and/or blue spaces. GSP has the potential to address health inequalities faced by migrants and refugees. We aimed to understand how GSP activities impacted the health and wellbeing of individuals in ethnically diverse communities within Hull and York (England) working alongside community organisations (n = 6) to deliver the research. This study utilised a mixed methods design; A pre-post intervention study design (n = 103) and face-to-face, semi-structured interviews (n = 20). Participants were recruited from community organisations (n = 6). Our study identified that a high proportion of people participating in GSP activity were able to sustain or improve their overall wellbeing. After 6-months of engagement in GSP activity, slight improvements were observed in scores for all ONS4 questions however only the anxiety construct demonstrated a statistically significant change (Mean change: -0.7 (95% CI -1.4 to 0.01). Qualitative data indicated community organisations are seen as trusted providers who can support access and engagement with green space. The study provided evidence that GSP can help to maintain and improve wellbeing within underserved communities, even at times of social and economic stress. Community organisations have a strong reach to those suffering the most health inequalities and can play a significant role in supporting health and wellbeing when empowered and provided with the appropriate resources
High-Rate and Selective Conversion of Low-Concentration Carbon Dioxide to Carbon Monoxide Using a Carbon Nanotube-Supported Molecular Electrocatalyst
Get PDFElectrocatalytic CO2 reduction reaction (e-CO2RR), powered by renewable electricity, is a compelling strategy to valorize CO2 into valuable chemicals and fuels. Herein, we report on MWCNT|CuPc-CoPc-modified gas-diffusion electrodes (GDEs) featuring molecular-level dispersion of cobalt phthalocyanine (CoPc) and copper phthalocyanine (CuPc) on the multi-walled carbon nanotube (MWCNT) support. The introduction of CuPc effectively mitigates CoPc aggregation, enabling tunable loading and fractional accessibility of electrochemically active CoPc sites, alongside improved CO2 adsorption capacity. Besides, the synergistic electronic interactions among CoPc, MWCNT, CuPc, and H2Pc, formed in situ via CuPc demetallization during electrolysis, optimized CO2 affinity, as evidenced by density functional theory calculations. With these promising attributes, the MWCNT|CuPc-CoPc-modified GDE with optimized CuPc content exhibits promising e-CO2RR performance across a wide CO2 concentration range (20%–98%). Notably, an efficient single-pass conversion of CO2 to CO is achieved, yielding a high CO yield of 65.7 ± 2.3% and an energy efficiency of 54.8 ± 1.9% using 20% CO2 at an ampere-level current (0.625 A). Furthermore, the developed electrode demonstrated robust stability, maintaining FECO above 80.4% over 72-h electrolysis under a simulated biogas atmosphere (40% CO2/60% CH4). These findings underscore the strong promise of molecularly engineered catalyst systems for efficient and selective CO production from low-concentration CO2 emission sources
Data sources:
Access Repository Dashboard
Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇