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Parameter sensitivity study of a morphology-adaptive CFD model for flat plate air lubrication
No full textIn this study, the effect of air lubrication on drag reduction on a downward-facing flat plate is investigated using a morphology-adaptive multiphase CFD model (MultiMorph). The model is applied to simultaneously simulate bubble drag reduction (BDR) and air layer drag reduction (ALDR) regimes. A sensitivity study of the MultiMorph submodels is performed to quantify the important parameters in air lubrication modelling using this simulation method. A comparison with experimental data using the baseline submodels showed 20-30 % deviations in drag reduction as a function of air flow rate with improved prediction of drag reduction in the transitional regime compared to a two-dimensional study. The submodel sensitivity study revealed that closure models accounting for lift and turbulent dispersion are found to affect drag reduction by up to ± 44.2 %. The value of the disperse bubble diameter is found to cause changes up to ± 28.1 %, assuming monodisperse bubbles. In contrast, drag reduction results are largely insensitive to the specific drag and wall lubrication closure model, and small changes in the turbulence damping strength and virtual mass coefficient cause differences below ± 10 %. These findings highlight some of the important modelling considerations and parameters for simulating air lubrication using the MultiMorph model.</p
Techno-economic evaluation of retrofitting power-to-methanol:grid-connected energy arbitrage vs standalone renewable energy
No full textThe power-to-methanol (PtMeOH) will play a crucial role as a form of renewable chemical energy storage. In this paper, PtMeOH techno-economics are assessed using the promising configuration from the previous work (Mbatha et al. [1]). This study evaluated the effect of parameters such as the CO2 emission tax, electricity price, and CAPEX reduction on the product methanol economic parity with respect to a reference case. Superior to previous economic studies, a scenario where an existing methanol synthesis infrastructure is 100 % retrofitted with the promising electrolyser is assessed in terms of its economics and the associated economic parity. The volatile South African electricity market is considered as a case study. The sensitivity of the PtMeOH and green H2 profitability are checked. Grid-connected and standalone renewable energy PtMeOH scenarios are assessed. Foremost, generalisable effect trends of these parameters on the net present value (NPV) and the levelized cost of methanol(LCOMeOH) and H2 (LCOH2) are discussed. The results show that economic parity of H2 (LCOH2 = current selling price = 4.06 €/kg) can be reached with an electricity price of 30 €/MWh and 70 % of the CAPEX. While the LCOMeOH will still be above 2 €/kg at 80 % of the CAPEX and electricity price of 20 €/MWh. This indicates that even if the CAPEX reduces to 20 % of its original in this study, and the electricity price reduces to about 20 €/MWh, the LCOMEOH will still not reach economic parity (LCOMeOH > current selling price = 0.44 €/kg). The results show that to make the retrofitted plant, with a minimum of 20 years of life span, profitable, a feasible reduction in the electricity price to below 10 €/MWh along with favourable incentives such as CO2 credit and reduction in CAPEX, particularly that of the electrolyser, and treatment of the PtMeOH as a multiproduct plant will be required
Inertia in Renewable Power Systems: A Review of Estimation Methods and Prac-tical Implementation
Get PDFThe dynamic behavior of modern power systems is being fundamentally reshaped by the increasing penetration of renewable energy sources with low or zero inertia, such as wind and solar PV. Consequently, in many regions, the rotational inertia traditionally provided by conventional synchronous generators has significantly declined. Since virtual inertia–achieved through synthetic inertia control– is not yet widely implemented, the overall system inertia has fallen well below that of traditional power systems. Accurate estimation of critically low inertia levels is therefore essential to ensure reliable and stable system operation. This review paper presents a comprehensive assessment of existing methods for inertia estimation in both conventional and renewable-rich power systems. It systematically compares techniques adopted by utilities, highlighting their practical applications, strengths, and limitations. Furthermore, the paper evaluates the feasibility of these approaches from an implementation perspective and discusses emerging challenges. Finally, it outlines future directions toward robust, adaptive, and real-time inertia estimation methods capable of supporting the secure operation of next-generation power systems.<br/
Compliance to prescribed training among recreational swimmers using augmented-reality swim goggles:A randomised controlled trial
No full textComplying with prescribed training plans is an important challenge for swimmers, as deviations from intended intensity or duration can reduce gains in performance and fitness. This randomised controlled trial investigated whether real-time visual feedback enhances compliance with prescribed training protocols among recreational swimmers. Fifty-seven participants were randomised into feedback (FB) and non-feedback (NFB) groups and completed 35 workouts over 12 weeks across three training volumes (small, medium, large). The FB group used FORM Goggles to receive real-time visual feedback; the NFB group used printed instructions and standard timing tools. Metrics included workout length count, workout effort, incomplete workouts, interval effort, rest time, and stroke type. Compliance was analysed using generalised linear mixed-effects models. The FB group demonstrated significantly better compliance with workout length count than the NFB group in the small and large plans (p < 0.004), with large effect sizes. Interval effort compliance was also higher in the FB group for the large training plan (69% vs. 58%, p = 0.044). Other metrics showed no meaningful group differences. These findings suggest that real-time visual feedback improves adherence to prescribed workout length and, to a lesser extent, interval effort, supporting its potential value in recreational swim training programmes.</p
Matrix weights on compact and non-compact domains
No full textWe study Muckenhoupt Ap conditions for matrix weights and their connections to related scalar properties for values of p in the range 1≤p<∞. Special emphasis is put on the process of diagonalisation of weights and on the role played by the domain of the matrix weight, where it is shown that there are several fundamental structural differences between weights defined on compact and non-compact domains.</p
Matrix weights on compact and non-compact domains
No full textWe study Muckenhoupt Ap conditions for matrix weights and their connections to related scalar properties for values of p in the range 1≤p<∞. Special emphasis is put on the process of diagonalisation of weights and on the role played by the domain of the matrix weight, where it is shown that there are several fundamental structural differences between weights defined on compact and non-compact domains.</p
Non-intrusive hourly occupancy detection in residential buildings using remotely readable water meter data: Validation and large-scale analysis
Get PDFOccupancy significantly influences building energy use; however, large-scale occupancy estimation, particularly in residential buildings, remains a challenge. While surveys and sensor data, particularly from remotely readable electricity meters, have been used for non-intrusive occupancy detection, water meter data have so far only been applied at daily resolution. This study introduces, validates, and applies a novel algorithm to infer hourly occupancy using data from remotely readable water meters. A new day definition, spanning noon to noon, is proposed to reflect typical daily rhythms better. Daily occupancy is inferred using water usage events and average consumption, akin to established methods. For days classified as occupied, hourly occupancy is estimated by associating water use with occupancy, followed by smoothing. Nighttime occupancy is inferred by linking the last evening and first morning occupancy. Validation was performed using one year of manually labelled data from ten households for daily occupancy (MCC = 0.982), and 147 days of unseen ground-truth data from nine households for hourly occupancy (MCC range: 0.267 to 0.795; building-weighted MCC = 0.594). Short absences were often misclassified as occupied, while longer absences (>3h) were reliably detected. Comparison with a state-of-the-art electricity-based algorithm showed superior performance of the proposed water-based method. Finally, the algorithm was applied to one year of data from 2,690 households, yielding plausible and interpretable occupancy patterns at both daily and hourly scales. These results demonstrate the method’s robustness and scalability, offering a promising approach for large-scale, non-intrusive occupancy monitoring.}<br/
Dietary Iron Deficiency in Adult Mice Increases Brain Uptake of High-Affinity, Anti-Transferrin Receptor Antibody RI7217
No full textABSTRACT Brain capillary endothelial cells (BCECs) express transferrin receptor 1 (TfR1) to ensure sufficient iron transport into the brain. Our main objective was to examine adult mice subjected to dietary iron deficiency (ID) for possible changes in the content of TfR1 in BCECs and the influence thereof on the uptake and possible transport across the blood?brain barrier (BBB) of high-affinity, rat anti-mouse transferrin receptor IgG2a antibody (clone RI7217) targeting the TfR1. We subjected adult, female mice to dietary ID for 8?weeks. Iron and copper were measured using inductively coupled plasma mass spectrometry (ICP-MS) in various tissues, including total brain, and fractions of brain tissue separated to contain a capillary enriched fraction (?capillary fraction?) and a post-capillary, non-endothelial-containing brain parenchymal fraction (?brain fraction?). Possible effects of ID on the cerebral angioarchitecture were estimated using 3D confocal microscopy of optically cleared brain samples labeled using intravenous injection of wheat germ agglutinin with subsequent machine learning-based segmentation and vascular tracing. TfR1 was quantified using ELISA. RI7217 antibodies were conjugated with 1.4?nm nanogold and brain uptake quantified using ICP-MS. ID significantly reduced the iron content in the capillary fraction, liver, spleen, kidney, heart, and skeletal muscles. ID increased the copper content in the brain. Analysis of cerebral cortical angioarchitecture revealed no changes following dietary ID, except for a minor increase in tortuosity of small-caliber vessels. Following ID, the concentration of TfR1 protein remained unchanged in total brain, and the isolated capillaries and brain fraction. In contrast, the uptake of nanogold-conjugated RI7217 was increased in total brain, the brain fraction, liver, spleen, and isolated retinae. The targeting to TfR1 in ID hence suggested increased brain uptake of RI7217. Hypothetically, elevated transport of RI7217 could occur due to increased trafficking of TfR1-containing vesicles through BCECs in ID.Brain capillary endothelial cells (BCECs) express transferrin receptor 1 (TfR1) to ensure sufficient iron transport into the brain. Our main objective was to examine adult mice subjected to dietary iron deficiency (ID) for possible changes in the content of TfR1 in BCECs and the influence thereof on the uptake and possible transport across the blood–brain barrier (BBB) of high-affinity, rat anti-mouse transferrin receptor IgG2a antibody (clone RI7217) targeting the TfR1. We subjected adult, female mice to dietary ID for 8 weeks. Iron and copper were measured using inductively coupled plasma mass spectrometry (ICP-MS) in various tissues, including total brain, and fractions of brain tissue separated to contain a capillary enriched fraction (“capillary fraction”) and a post-capillary, non-endothelial-containing brain parenchymal fraction (“brain fraction”). Possible effects of ID on the cerebral angioarchitecture were estimated using 3D confocal microscopy of optically cleared brain samples labeled using intravenous injection of wheat germ agglutinin with subsequent machine learning-based segmentation and vascular tracing. TfR1 was quantified using ELISA. RI7217 antibodies were conjugated with 1.4 nm nanogold and brain uptake quantified using ICP-MS. ID significantly reduced the iron content in the capillary fraction, liver, spleen, kidney, heart, and skeletal muscles. ID increased the copper content in the brain. Analysis of cerebral cortical angioarchitecture revealed no changes following dietary ID, except for a minor increase in tortuosity of small-caliber vessels. Following ID, the concentration of TfR1 protein remained unchanged in total brain, and the isolated capillaries and brain fraction. In contrast, the uptake of nanogold-conjugated RI7217 was increased in total brain, the brain fraction, liver, spleen, and isolated retinae. The targeting to TfR1 in ID hence suggested increased brain uptake of RI7217. Hypothetically, elevated transport of RI7217 could occur due to increased trafficking of TfR1-containing vesicles through BCECs in ID. (Figure presented.).</p
Mapping of international and national funding agencies and strategies for that support societal impact and knowledge mobilisation
No full textTrygFonden has commissioned this report to explore how knowledge mobilization and societal impact are incorporated into funding strategies by Danish and international foundations. The report aims to explore how foundations use knowledge mobilization to strengthen the practical implementation of knowledge and impact within research environments and projects. Knowledge mobilization provides a conceptual framework for systematically understanding how knowledge is exchanged and co-created between research and practice. The concepts and structures used to describe different scales and tools for knowledge mobilization are identified across foundations and we show how an increasing strategic focus on research-to-practice partnerships and instrumets are permeating the funding lancscabe. TeamArbejdsliv (Ulrik Gensby) and Aalborg University (David Budtz Pedersen) have jointly prepared the report “Mapping of international and national funding agencies and strategies for that support societal impact and knowledge mobilisation.” The mapping documents how eight Danish and international foundations support knowledge mobilization in the research activities they fund.TrygFonden has commissioned this report to explore how knowledge mobilization and societal impact are incorporated into funding strategies by Danish and international foundations. The report aims to explore how foundations use knowledge mobilization to strengthen the practical implementation of knowledge and impact within research environments and projects. Knowledge mobilization provides a conceptual framework for systematically understanding how knowledge is exchanged and co-created between research and practice. The concepts and structures used to describe different scales and tools for knowledge mobilization are identified across foundations and we show how an increasing strategic focus on research-to-practice partnerships and instrumets are permeating the funding lancscabe. TeamArbejdsliv (Ulrik Gensby) and Aalborg University (David Budtz Pedersen) have jointly prepared the report “Mapping of international and national funding agencies and strategies for that support societal impact and knowledge mobilisation.” The mapping documents how eight Danish and international foundations support knowledge mobilization in the research activities they fund