20505 research outputs found
Sort by
Advances in design of high-performance heterostructured scintillators for time-of-flight positron emission tomography
Get PDFCore to advancing time-of-flight positron emission tomography (ToF-PET) toward a less invasive, more flexible procedure with a higher diagnostic power is the development of enhanced radiation detector materials. One promising avenue is the development of heterostructured scintillators where multiple materials work in synergy to exceed the performance of each individual component. Applied to ToF-PET detectors, one component contributes predominantly to the absorption of gamma rays and the other to the creation of ultra-fast photons. Whilst other authors have proposed various concepts, heterostructured scintillators are still in their infancy and scientifically guiding their development remains a challenge. Toward this aim and based on simulation and modeling developments, heterostructure properties are directly linked to ToF-PET performance. This is made possible by redefining the notions of detector photo-peak efficiency and timing response, as defined for monolithic detectors, in the context of heterostructured scintillators. Their overall potential is then discussed as a function of the materials and design used. This provides a quantitative framework to rapidly and efficiently support the advancement of heterostructured detectors for ToF-PET technology.Engineering and Physical Sciences Research Council (EPSRC): EP/S013652/1Advanced Theory and Simulation
Leave or not to leave? the impact of managerial work-life support and work engagement on the outcomes of work-to-life conflict for China’s new generation employees
Get PDFThis paper explores how work engagement and managerial work-life support can influence the relationship between work-to-life conflict and turnover intention for China’s new generation employees. Drawing on job demand-resources (JD-R) theory and time-lagged survey data, we developed a moderated mediation model which reveals the mediating effect of work engagement on the relationship between work-to-life conflict and turnover intention, and the moderation effect of managerial work-life support on the relationship between work-to-life conflict and work engagement. The findings show that work engagement serves as a personal resource for new generation employees to buffer the negative impact of work-life conflict on turnover intention, and managerial work-life support serves as a key job resource to influence the mediating effect of work engagement when work-life conflict occurs. Research contributions, implications, and limitations are discussed.Asia Pacific Business Revie
Price promises, trust deficits and energy justice: public perceptions of hydrogen homes
Get PDFIn an era characterised by political instability, economic uncertainty and mounting environmental pressures, hydrogen fuel is being positioned as a critical piece of the global energy security and clean energy agenda. The policy push is noteworthy in the United Kingdom, where the government is targeting industrial decarbonisation via hydrogen, while exploring a potential role for hydrogen-fuelled home appliances. Despite the imperative to secure social acceptance for accelerating the diffusion of low-carbon energy technologies, public perceptions of hydrogen homes remain largely underexplored by the researcher community. In response, this analysis draws on extensive focus group data to understand the multi-dimensional nature of social acceptance in the context of the domestic hydrogen transition. Through an integrated, mixed-methods multigroup analysis, the study demonstrates that socio-political and market acceptance are strongly interlinked, owing to a trust deficit in the government and energy industry, coupled to underlying dissatisfaction with energy markets. At the community level, hydrogen homes are perceived as a potentially positive mechanism for industrial regeneration and local economic development. Households consider short-term disruptive impacts to be tolerable, provided temporary disconnection from the gas grid does not exceed three days. However, to strengthen social acceptance, clearer communication is needed regarding the spatial dynamics and equity implications of the transition. The analysis concludes that existing trust deficits will need to be overcome, which entails fulfilling not only a ‘price promise’ on the cost of hydrogen appliances, but also enacting a ‘price pledge' on energy bills. These deliverables are fundamental to securing social acceptance for hydrogen homes.Engineering and Physical Sciences Research Council (EPSRC): EP/T518104/1
Cadent Gas Lt
Tribological characterisation and modelling for the fused deposition modelling of polymeric structures under lubrication conditions
Get PDFIn recent years, additive manufacturing technology, particularly in plastic component fabrication, has gained prominence. However, fundamental modelling of the influence of materials like ABS, PC, and PLA on tribological properties in fused deposition modeling (FDM) remains scarce, particularly in non-lubricated, oil-lubricated, and grease-lubricated modes. This experimental study systematically investigates the effects of material type, lubrication method, layer thickness, and infill density on FDM component tribology. A tribology analysis is conducted using a TRB3 tribometer. The results indicate a coefficient of friction (CoF) range between 0.04 and 0.2, generally increasing and decreasing with layer thickness and filler density. The lubrication impact hinges on the material surface texture. The study models the intricate relationships between these variables via full-factor analysis, showing a strong alignment between the modelled and measured friction coefficients (an average error of 3.83%). Validation tests on different materials affirm the model’s reliability and applicability.Polymer
Hydrogen-enriched natural gas co-firing: a comparison of FGM and EDC models
Get PDFTo facilitate the transition from natural gas to a future hydrogen economy, the combustion of natural gas/hydrogen blends in gas turbines will play an important role in power generation. The influence of hydrogen content on technically premixed swirl-stabilized flame using large eddy simulation has proven to be powerful but with high computational costs. Hence, RANS-based models are useful for preliminary investigations and sensitivity studies. Flamelet Generated Manifold (FGM) and Eddy-Dissipation Concept (EDC) are two widely used RANS-based combustion models. EDC, in particular, accounts for the interaction between chemistry and turbulence using detailed chemical mechanisms, but at the cost of higher computational resources. FGM preprocesses the flamelet as a function of mixture fraction and progress variable and pre-integrates the chemistry-turbulence interaction into a Probability Density Functions (PDF) table, which makes FGM computationally inexpensive. This study aims to compare the predictions of these models with experimental data of a methane-fueled technically premixed swirl-stabilized low-pressure burner. The better-performing model is used to evaluate the influence of methane and hydrogen blends (up 40% by volume) in a higher-pressure burner also validated with experiments. The study has shown that EDC produces better agreement with the experimental data than FGM in estimating the flame temperature, flow velocity, and carbon dioxide profiles. FGM did not correctly capture the flame pattern and overestimated the reaction rate. This is possibly due to its simplified preprocessed chemistry mechanism, which could not evaluate the local thermal properties of the gas mixture properly. For the higher pressure evaluation at 5 bar, the EDC model captured the influence of hydrogen content addition on flame behaviour. As the hydrogen content increased, the chemical reaction rate increased, and the flame length indicated by OH decreased. This reduction in flame length is consistent with the experimental results. The CFD showed that at 20% H2, the change in NOx emission compared to 100% methane is negligible using the mass of NOx per unit of heat release calculation. A slight increase in NOx is shown for the same case using the concentration by volume corrected to 15% O2 approach. Nevertheless, both approaches showed NOx reductions at 40% H2. This study has shown that the behaviour of a technically premixed swirl-stabilized flame-firing methane/hydrogen blend is well represented by a non-adiabatic RANS-EDC model with low computation cost. This confirms its applicability in evaluating acceptable lean premixed burners characteristics for gas turbines.ASME Turbo Expo 2023: Turbomachinery Technical Conference and Expositio
Modelling the potential of rainwater harvesting to improve the sustainability of landscape and public garden irrigation
Get PDFAccess to water for irrigating amenity landscape and public gardens is under intense pressure due to the rising competition for water between different sectors, exacerbated by increased drought risk and climate change. Rainwater harvesting (RWH) has the potential to reduce the economic impacts of restrictions on irrigation abstraction in dry years and to build resilience to future water shortages. This study investigated the hydrological viability of RWH for the landscape and public garden sector based on an analysis of five Royal Horticultural Society gardens. A RWH model was developed and combined with on-site observations, key informant interviews and GIS analyses, to estimate irrigation demands and the volumes of harvested rainfall for contrasting agroclimatic years. The results showed that gardens located in wetter regions and with low irrigation water demand to harvestable area ratio had a higher RWH potential and could almost exclusively rely on rainwater to meet irrigation demand, even in dry years. RWH potential is more limited for gardens in drier regions where they would require larger areas to harvest rainwater and for storage. Appropriately designed rainwater harvesting systems offer the potential to remove most of the risk of irrigation abstraction restrictions during dry years and associated impacts on amenity planting quality and visitor experience.Journal of Environmental Managemen
Chapter 15: Normalization of deviance in projects: its causes and implications for effective governance
No full textOrganizational mistakes and accidents have a long history in practice and have been studied extensively in the engineering and organizational literature. One of the primary causes of persistent organizational error is the existence of deviance, i.e., behavior violating organizational norms. This chapter examines the behaviors and motivations of project team members in situations where deviant behaviors have been accepted and normalized as part of project operations. It discusses how normalization of deviance (NoD) manifests in terms of (1) project proposals and strategic misrepresentation, (2) client/contractor relationships, (3) planning and scheduling dynamics, and (4) workplace safety, and provides examples of NoD in practice. The chapter concludes with implications of NoD for organizational performance improvement and offers advice for how to avoid NoD situations
A novel Ti/Al interpenetrating phase composite with enhanced mechanical properties
Get PDFLightweight, energy-absorbing materials with excellent mechanical properties are highly desired in practical engineering applications. A novel Ti-Al interpenetrating phase composite (Ti/Al IPC) was successfully fabricated by filling an Al alloy (ZL102) in the pores of an additively manufactured triply periodic minimal surface (TPMS) structure composed of Ti alloy (TC4). This IPC demonstrates a remarkable combination of attributes, including a high yield stress of 305 MPa, a Young's modulus of 64 GPa, and an ultimate tensile strength of 420 MPa. These mechanical properties are 1.5 to 2.9 times stronger than those of a single TC4 TPMS structure of the same size. The enhanced performance can be attributed to the synergistic strengthening and toughening effect resulting from the internal interpenetration of the ZL102 phase within the structure.The authors wish to gratefully acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 52105418), the Natural Science Foundation of Hunan Province (Grant No. 2023JJ20069), and the key scientific research project of Hunan Provincial Department of Education (Grant No. 23A0001)Materials Letter
The role of supply chains for the sustainability transformation of global food systems: a large-scale, systematic review of food cold chains
Get PDFGlobal food systems need an urgent transformation to be compatible with sustainable development. While much of the recent academic discussion has focused on food production and consumption, food supply chains have received considerably less attention. Here, we conduct a large-scale, systematic literature review of 48,014 academic articles to assess the links between the food cold chain literature and sustainable development. We find a multitude of deep links between food cooling and the Sustainable Development Goals (SDGs), but also identify underexplored areas of sustainable food cooling research regarding its (1) goals, (2) analytical depth, and (3) context specificity: There is a limited understanding how several relevant synergies between SDGs can be captured, how to best design sustainable food cold chains across multiple value chain stages, and how to scale sustainable cold chains in low-income and lower-middle-income country contexts. We recommend to explicitly consider the salient interconnections between SDGs, increase the analytical depth by deploying more system-level approaches across entire value chains, and focus on localized solutions in contexts where food supply chains are most underdeveloped.Journal of Industrial Ecolog
Assessing consistency in the aerobic co-composting of faecal sludge and food waste in a municipality in Ghana
Get PDFBackground:
A faecal sludge (FS) co-composting study assessed the extent of consistency in compost characteristics between and within batches. The study focused on the consistency of the co-composting process by measuring the variability of key parameters.
Method:
The set up consisted of 12 FS and food waste (FW) co-composting piles in three successive batches (1, 2 and 3). Consistency was assessed in the three successive batches of co-composted FS and food waste (FW). Within batches, consistency was assessed in each of them by dividing it into four separate replicate piles. Characteristics of interest were E. coli, as well as selected physico-chemical parameters (pH, EC, Mg, Ca, N, NH4-N, NO3-N, P, avail. P, and K) and heavy metals (Se, Fe, Cd, Cu, Hg, Ni, Pb and Cr). Data were subjected to analysis of variance (ANOVA) using SPSS.
Result:
Results show that, E. coli levels were not consistent between the successive batches during the entire co-composting process. While variations between batches were only observed for EC and nutrient parameters, variations were evident for several measured characteristics within batches. The measured coefficient of variations (CVs) within batches ranged between 0–125% and 3–111% for heavy metals and nutrients, respectively.
Conclusion:
In conclusion, there was less consistency in nutrients between successive batches and CV within batches was wide. Consistency levels for E. coli may not be an issue if pathogen inactivation is complete.
Recommendation:
It is recommended that a threshold value be created for determining what is an acceptable level of variation in FS co-composting.Funding for the research was from Sue White Fund for Africa (SWF)—Cranfield University and the International Water Management Institute (IWMI). Funding from the UKRI GCRF QR also facilitated some of the laboratory analysis.Environmental Systems Researc