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Improvement of S-shaped instability and power performance of a reversible pump-turbine runner
No full textThe reversible pump turbine (RPT) is likely to enter the S-characteristic zone, thereby inducing pressure fluctuations and oscillations to the grid connection. An innovative optimization framework of RPT runner is presented to mitigate the detrimental flow conditions associated with the S-curve under turbine mode. Comprehensive runner geometric parameters were considered with the optimal Latin hypercube (OLH) sampling technique to generate different designs. Computational fluid dynamics (CFD) was adopted to characterize the RPT hydraulic efficiency and unstable S-characteristics curve, in which the position of the second inflection point was innovatively selected as the objective function. The CFD-driven surrogate-based design methodology was achieved by artificial neural network (ANN). The multi-objective optimization evolutionary algorithm guided the search for the optimal runner configuration with high efficiency and improved S-characteristics. The vortices in the runner channels and high-speed water ring in the vanless area both blocking the flow passage are alleviated in the two selected optimized RPT runners. The total pressure head associated with the intensity of vortices is deceased in the optimized runner, resulting in the improved S-shape characteristic. Runner with higher arches and negative blade lean angle of leading edge is conducive to the smooth streamline and avoidance of the flow separation.Funder: National Natural Science Foundation of China (52509133); Natural Science Foundation of the Jiangsu Higher Education Institutions of China Programme - General Programme (24KJD570001); Jiangsu Provincial Double-Innovation Doctor Program (JSSCBS20221363); Yangzhou Lv Yang Jin Feng Ji Hua (YZLYJFJH2021YXBS118)</p
CO2 from biogas: valorisation, economic and environmental impacts in circular carbon systems
No full textThe production of biogas through anaerobic digestion (AD) of organic-renewable feedstocks is recognized as a viable solution within the renewable energy sector. Biogas typically contains a methane concentration ranging from 60 to 70%, presenting a significant opportunity for energy generation. However, the co-generated carbon dioxide (CO2), which constitutes approximately 30–40% of biogas, poses challenges to overall energy efficiency, thus necessitating the implementation of purification methods to enhance methane concentrations. It is noteworthy that the production of one ton of biomethane results in the generation of approximately two tons of biogenic CO2. This reality opens avenues for carbon capture, storage, and valorization strategies. The biogas industry is beginning to recognize CO2 not merely as a byproduct to be discarded, but as a valuable resource for the synthesis of biomethane, chemicals, fuels, and even building materials. There is a growing interest in utilizing biogenic CO2 as a climate-friendly feedstock, with “bio-Carbon Capture and Utilization” (bio-CCU) practices facilitating the development of sustainable fuels, chemicals, and materials. The article extends to various methods of valorization for biogenic CO2, providing an analysis of techniques for separating and upgrading CO2 derived from biogas. This assessment encompasses both physical and biological methodologies within the carbon capture, utilization, and storage (CCUS) framework. The article further demonstrates both in-situ and ex-situ processes, including biological methodologies that employ microorganisms for CO2 conversion, as well as thermo-physicochemical processes that transform CO2 into biobased products. Additionally, the article demonstrates the economic and environmental advantages associated with the strategic utilization of biogenic CO2. Repurposing this resource is vital for achieving sustainability goals, particularly in renewable energy sectors, where it can significantly enhance energy efficiency and reduce waste. Finally, the article emphasizes the importance of these practices in climate change mitigation, advocating for a circular economy that prioritizes carbon reuse over atmospheric emissions, thus contributing to the advancement of a sustainable future.Full text: CC BY license;</p
Comparative absorption factor (CAF) for screening ionic liquids to capture CO2 in biogas, natural gas, and shale gas: Effect of operating conditions
No full textUpgrading clean energy fuels, such as biogas, natural gas, and shale gas, requires the capture of CO2 to enhance their heating value. Ionic liquids (ILs) are promising absorbents for this purpose, but the vast number of available ILs necessitates an efficient screening method. The Comparative Absorption Factor (CAF) developed in our previous study can estimate the total annual cost (TAC) of CO2 capture from biogas, which is a key advantage over alternative screening methods. However, CAF does not consider the effects of operating conditions such as CO2 concentration, pressure, and temperature. To address this limitation, a modified CAF (CAFmodified) that incorporates these factors was proposed. Given the linear relationship between the original CAF and TAC, three representative ILs ([C10mpy][DCA], [C1mim][tfo], and [C1py][tfo]) were selected from 490 ILs based on their melting point, viscosity, and original CAF values. Subsequently, process simulations for these ILs were conducted using Aspen Plus, considering a wider range of operating conditions: CO2 concentrations of 30–50 vol%, temperatures of 303.15–318.15 K, and pressures of 7–15 bar. These simulations were used to determine the Aspen Plus-derived TAC, which served as the basis for proposing CAFmodified. Finally, data for Aspen Plus-derived TAC from the previous study and for 6 additional ILs over a broad range of operating conditions were used to compare with the TAC values estimated by CAFmodified. The results showed an average relative deviation of 16%, indicating that CAFmodified is effective for screening ILs for CO2 capture under varying operating conditions.Full text: CC BY license;Funder: National Natural Science Foundation of China (No. 21838004, 22011530112, 22494713); Swedish Energy Agency and STINT (CH2019-8287);</p
Inpatient nurses' experience of mental health as a consequence of care during covid-19 pandemic
No full textBakgrund: Arbetsrelaterad mental ohälsa är ett värdsomspännande problem som kan leda till kognitiva, kroppsliga och emotionella problem. Sjuksköterskors arbete inom slutenvården med patienterna var intensivt under pandemins förlopp. Enligt rapportering till Världsoorganisationen blev över 70 000 patienter inskrivna på sjukhus per vecka världen över under covid-19 pandemins kulmen från början av 2021-2022. Syfte: Studiens syfte var att belysa sjuksköterskors upplevelse av psykisk hälsa som konsekvens av omvårdnadsarbetet i slutenvården under covid-19 pandemin. Metod: Studien genomfördes som en kvalitativ innehållsanalys med manifest ansats. Litteratursökningen genomfördes i PubMed, Medline och CINAHL vilket resulterade i 10 kvalitativa artiklar som bearbetades i analysen. Resultat: Analysen resulterade i fyra huvudkategorier: Att pandemin är källa till psykiskt lidande. Att konfronteras med maktlöshet, död och moralisk stress. Att böra vårdens börda till pris av egen hälsa. Att finna styrka, gemenskap och utveckling trots trauma. Slutsats: Sjuksköterskor som arbetat inom slutenvården under pandemin beskriver upplevelser av att plikttroget utföra sitt arbete och trycka undan de egna känslorna under pandemin och nu befinner sig i ett efterförlopp med utbrändhet, PTSD och empati trötthet till följd av detta. Resultatet indikerar att mer forksning behövs inom detta relativt outforskade område, för att kunna säkerställa en god arbetsmiljö för sjuksköterskor i framtiden.
Registered nurses’ work to alleviate symptoms in patients with chronic obstructive pulmonary disease : An integrative review
No full textKronisk obstruktiv sjukdom (KOL) är en av de vanligaste dödsorsakerna i världen. Patienter som lever med KOL beskriver att sjukdomen har stor inverkan på deras liv. Omvårdnadsåtgärder har stor betydelse för att förbättra livskvalitén hos patienter med KOL. Syftet var att sammanställa kunskap om sjuksköterskors arbete för att lindra symtom hos patienter med KOL. Litteraturstudien genomfördes som en integrerad kunskapsöversikt. Genom en systematisk sökning inkluderades artiklar som hade kvalitativ, kvantitativ samt mixad metod för att få en större och mer omfattande förståelse. Vår analys resulterade i fyra slutkategorier: Patientutbildning och information, Stöd till patienter, Egenvård och kombinerad behandling och Patienters upplevelse av relation, motivation och öppenhet. Sjuksköterskor har en central roll i att arbeta personcentrerat genom att individanpassa informationen, stödja egenvård och främja patienters delaktighet i vården. En god omvårdnad kan bidra till ökad trygghet, förbättrad livskvalitet och förstärka egenvård.
Blue-green infrastructure for climate resilience - quantifying stormwater hydrology impacts
No full textBlue Green Infrastructure (BGI) has emerged as robust measures for managing stormwater, offering benefits such as reducing urban flooding, promoting groundwater recharge etc. However, recent studies highlight that these facilities often underperform during climate-induced intense rainfall events in urban areas. In addition, implementation of BGI in urban catchments is often challenging because many there are many different options and design considerations for BGI and commonly a lack of space. Therefore, there is greater need that 1) a more structured approach is applied during the selection, distribution and design of different BGI alternatives in urban catchments, and 2) facilities like bioretention are adapted to handle these intense events more effectively. The licentiate titled “Blue-green infrastructure for climate resilience - quantifying stormwater hydrology impact” focuses on advancing the understanding of design and implementation of Blue-Green Infrastructure (BGI) in catchment scale, with the explicit focus on design improvement of bioretention facilities by using modelling tools. The licentiate has an overall 3 scientific articles. Paper 1 develops different BGI alternatives by considering spatial scale and design complexity in urban environments having diverse land use characteristics. The study quantifies to what extent hydrological outcomes such as surface runoff, infiltration, and pre-development flow varies with different BGI alternatives in these catchments. One of the results obtained from this study showed that in residential areas, which offer more spaces for planned integration of stormwater control measures, engineered BGI alternatives showed the highest potential to reduce flooding while in densely built inner city catchments the more natural BGIs showed higher potential. Paper 2 evaluates the reliability of the SWMM model used in Paper 1 for bioretention modeling by comparing calibrated and uncalibrated models with observed data. The findings confirm that SWMM is a reliable tool for modeling bioretention systems, accurately capturing key hydrologic processes, especially after calibration. While first study is about how different BGIs can be combined to achieve various hydrologic benefits at catchments, the third study is about effect of different bioretention design variable in managing stormwater hydrology at local scale. Paper 3, by using the calibrated model in Paper 2, explores 54 different biofilter design options, to assess the impact of key design factors—ponding depth, hydraulic conductivity, filter media fraction and storage connection —on different stormwater performance indicators. In general, this study showed that a balanced approach is required while designing bioretention as there are trade-offs between optimizing for volume reduction during daily events (e.g. higher filter media fraction) and reducing overflow occurrences during high-intensity events (e.g. lower filter media fraction, high hydraulic conductivity). Overall, this thesis provides valuable insights and practical recommendations for enhancing the effectiveness of BGI in urban catchments for climate adaptive stormwater management solutions, and with explicit focus on designing bioretention systems.
Numerical assessment of the high cycle fatigue behavior of high strength steels affected by shear-cutting operations
No full textShear-cutting processes are arguably among the most preferred technologies for performing material removal operations in the manufacturing of chassis components due to the combination of high production rate and cost-efficiency. Nevertheless, they may severely jeopardize the fatigue response of high strength metals, compromising the current trend of using this class of materials for weight reduction of automotive chassis parts. Thus, the generation of reliable data featuring the influence of these operations on the material fatigue behavior is essential to further support this lightweighting tendency. Commonly employed for this aim, traditional fatigue tests are usually time-consuming and rather expensive. In this context, numerical simulations arise as a viable alternative, providing not only material-related information but also assisting engineers in the design of new components. In this work, an isotropic damage-based high cycle fatigue model is employed to estimate the fatigue life of trimmed and punched specimens of two complex phase steels. The residual stresses obtained from each process simulation and the roughness measured on the cut surface are included in the model to account for the influence of these operations on the material fatigue strength. Furthermore, standard uniaxial tensile properties and S–N data resulting from fatigue tests on as-polished specimens are the only material information required. A good agreement is found between the numerical fatigue life predictions and the experimental measurements, remaining below an error factor of three for all the estimated cases. In addition to coupon specimens, the model is also readily extensible to component-level applications, enabling the fatigue assessment of metallic engineering structures featuring shear-cut surfaces.Validerad;2025;Nivå 2;2025-08-19 (u0);Full text license: CC BY</p
Charge-regulated reversal of acetate/chloride selectivity on functionalized graphene via dehydration-driven diffusion
No full textSeparating monovalent anions of similar size and charge, such as acetate (Ac−) and chloride (Cl−), remains highly challenging in membrane processes. Using molecular dynamics simulations, we explored functionalized graphene surfaces with tunable fractions of protonated amine (-NH3+) and deprotonated carboxyl (-COO−) groups (ratios 0:10 to 10:0) in a NaAc/NaCl mixed solution. We identified a charge-regulated selectivity reversal process: -COO−-rich, negatively charged surfaces showed only a weak Cl− preference (αCl−/Ac− = 1.06–2.71), whereas -NH3+-dominated, positively charged surfaces achieved strong Ac− selectivity, up to 14.86, for an 8:2 -NH3+:-COO− ratio. Decomposing permeability into solubility and diffusivity showed that the Ac− advantage on -NH3+-rich surfaces was more than 80 % diffusion-dominated, whereas the small Cl− preference on -COO− surfaces reflected slight, counterbalancing changes in solubility and diffusivity. Interfacial hydration analysis linked the selectivity to the dehydration difference between Ac− and Cl−. The maximum Ac−/Cl− selectivity coincided with the largest ΔNAc−-Cl− between the bulk and the interface. Together, our work reveals interfacial dehydration-controlled diffusion as the main mechanism for separating Ac− from Cl− on charge-regulated graphene surfaces and offers a quantitative design rule recommending setting the -NH3+:-COO− ratio near 8:2 to optimize membrane functionalization for challenging monovalent anion separations.Validerad;2025;Nivå 2;2025-11-21 (u4);Funder: National Natural Science Foundation of China (22378182, 22494713); the Jiangsu Provincial Department of Science and Technology (BK20232010); the State Key Laboratory of Materials-Oriented Chemical Engineering (SKL-MCE-22A02);This article is part of a Special issue entitled: ‘Desalination technology’ published in Separation and Purification Technology.</p
Halogen-free deep eutectic solvents as ambient temperature supercapacitor electrolytes
No full textHere, we introduce three new halogen-free salts based on the green, sustainable, and hydrolytically stable saccharinate (Sac) anion, and their deep eutectic solvents (DESs) with ethylene glycol (EG). All the three salts exhibit distinct and well-defined thermal behaviors, ranging from ionic plastic crystals (IPCs) to supercooled liquids and classical ionic liquids (ILs). In contrast, their corresponding DESs display no detectable thermal events, a clear indication of successful DES formation, which is well supported by FTIR spectroscopy and suggests that EG interacts with the −CO and −SO2 groups of the Sac anion. DES with [EMPip][Sac] offers superior ion transport and electrochemical properties, supporting a voltage range up to 5.7 V, and as an electrolyte in a symmetric supercapacitor, a specific capacitance of 46.5 F g−1 at 5 mV s−1, an energy density of 9.9 Wh kg−1, and power density of 1022 W kg−1, at a current density of 0.2 A g−1. The capacitor retained 99 % of its initial capacitance after 20,000 cycles at ambient temperature. Altogether, these halogen-free DES electrolytes offer promising electrochemical properties, making them ideal electrolytes for supercapacitors operating at ambient temperatures over a wide potential range.Validerad;2025;Nivå 2;2025-12-01 (u5);Full text license: CC BY 4.0;Funder: Åbo Akademi University</p
Autonomy for whom? implications of cyber–physical mining systems for operator work and organisation
No full textThis paper examines the implementation of a cyber–physical mining system, the Autonomous Haulage System (AHS), from a work-system perspective. It explores how automation reconfigures the balance between human, technological, and organisational elements, with a focus on operator roles. Drawing on an explorative case study in an open-pit mine, the analysis applies Balance Theory to interpret how work and organisational relations are reshaped as autonomy is redistributed between humans and technology. Findings show that while the AHS contributes to improved safety and predictability, it also introduces greater work-task diversity and responsibility, increased standardisation and bureaucratisation, and reduced social interaction with emerging risks of isolation. Operators remain central to supervision, coordination, and adaptation, but their work becomes more procedural and dependent on organisational structures and formal routines. The study concludes that maintaining balance in cyber–physical mining systems is an ongoing organisational responsibility that relies on social cohesion, mutual trust, and continuous learning. Ultimately, the findings emphasise that the effectiveness of mining automation depends as much on collective engagement and organisational adaptation as on technological performance.Validerad;2025;Nivå 2;2025-12-02 (u4);Fulltext license: CC BY</p