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Partially Superconducting Machines with Liquid Hydrogen for Marine Propulsion
No full textThis paper contributes to the field of naval propulsion by designing and analyzing a partially superconducting motor with characteristics tailored to ships. It provides a comprehensive overview of Siemens\u27 pivotal contributions to superconducting motor advancements and highlights the benefits of this technology in the naval sector. The latest Siemens motor, HTS-3, demonstrates remarkable performance. To advance the sector, a partially superconducting motor for modern maritime applications has been developed. Key performance data demonstrate its advantages: the 8-pole motor operates at a low speed of 225rpm, delivers torque exceeding 600kNm, and achieves a volumetric power density of 9.3MW/m3. The field winding employs disk-up-down-assembly coils in a rectangular topology (DUDA-r). Its high power density, combined with a reduced carbon footprint when using hydrogen as both a coolant and a fuel, makes this motor highly attractive for propulsion applications
Qualitative modeling of etch-pit formation (dissolution) on the K-feldspar surface through phase-field approach
No full textFeldspar dissolution is a widespread occurrence in clastic bedrock reservoirs in petroleum-bearing zones, and it has a serious influence on reservoir quality [1]. This present study demonstrates a diffused modeling strategy, namely the phase-feld method, for addressing the phenomenon of dissolution of the (001) K-feldspar (Orthoclase) surface, which happens with the development of diamond shape etch pits in two and three dimensions. The [100] and [010] axes are parallel to the etch pit diagonals, and similarly the pit boundaries are present laterally to the (6 5 6), (6 5’ 6), (6’ 5 11), and (6’ 5’ 11) planes [2]. On the (001) surface, the size of the etch pits and the global surface retreat have been observed to rise linearly with the passage of time. A thermodynamically consistent phase-feld model was devised to account for anisotropies in surface energy and kinetic mobility associated with diamond-shaped etch pits that occur during dissolution. The proportional growth parameters of a pit morphology were calibrated using the values found in literatures. There are two novel elements to this work: (I) 3D-Modeling of diamond etchpit development on orthoclase (K-feldspar) surfaces in a bi-crystalline and multigrain system, and (II) identifying growth patterns of these pits to better understand and remark on their impact on sandstone’s porosity and permeability. Additionally, the fndings of the porosity study enabled us to evaluate the development of porosity in a sandstone pack through time as a consequence of partial and total orthoclase crystal dissolution. Simultaneously, the permeability study was performed using a fluid-flow simulation via a polycrystalline grain pack, which validates the fundamental notion of the implications based on Kfeldspar dissolution. The offered prescription may qualitatively forecast dissolution processes in diverse crystal-liquid geological systems [3].
REFERENCES
[1] Xiao, Meng, et al. ”Feldspar dissolution and its influence on reservoirs: a case study of the Lower Triassic Baikouquan Formation in the northwest margin of the Junggar Basin, China.” (2018).
[2] Pollet-Villard, Marion, et al. ”Influence of etch pit development on the surface area and dissolution kinetics of the orthoclase (001) surface.” Chemical Geology (2016): 79-92.
[3] Prajapati, Nishant, et al. ”Quantitative Phase-Field Modeling of Faceted Crystal Dissolution Processes.” Crystal Growth & Design (2021): 3266-3279
Multi-Domain Dependency Graphs for Analyzing Cyber-Physical Systems
No full textCyber-Physical Systems (CPS) combine hardware, software, and physical processes from different engineering fields, and often exist in different product variants and versions. Working across these domains introduces numerous connections and dependencies that make it challenging to analyze systems, identify errors, and track how changes impact the entire product. A major challenge is the lack of a single, unified system model that can represent all system elements, their relationships, and the extra information created during development, such as metadata about authorship, testing results, or change history. Multi-Domain Dependency Graphs (MDG) are introduced as a graph-based modeling approach to address this need. MDG provides a unified system model that includes not only the core technical artifacts from different engineering domains, but also metadata, support for managing product variants and versions, and the ability to capture derived analysis results. The MDG structure uses layers to separate core system elements, variant and version information, metadata, and computed data, making it possible to filter and focus analyses on relevant parts of the system. By supporting integrated feature models and enabling systemwide analyses, such as change impact assessments and clustering, MDG provides a practical foundation for managing CPS in a consistent and scalable manner. Organizing information in layers helps reduce the size of data that needs to be processed and improves the ability to extract insights across domains, making MDG well-suited for advanced engineering tasks and applications involving graph-based AI
High pressure entrained flow gasification: Validated data from 5 MW pilot-scale experiments for process monitoring, optimization and scale-up
No full textDietary phosphate exposure–strategies to protect vulnerable population groups
No full textPhosphorus is commonly part of the diets in developed countries, both as a natural component of protein-rich foods and as a food additive. Consumption of food containing high amounts of phosphate as a food additive has continued to rise over time, resulting in increasing dietary exposure to phosphate. In 2019, an evaluation of phosphoric acid and phosphates conducted by the European Food Safety Authority (EFSA) identified young populations as groups with exposures exceeding the Acceptable Daily Intake (ADI), and also raised concern that the current ADI may not be sufficiently protective for individuals with an impaired renal function, which may account for 10% of the general population. The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) critically reviewed the safety of dietary phosphate, with a particular focus on the kidney as the primary target organ, taking into account the occurrence and content of phosphate in food, the most recent exposure estimates, the bioavailability of phosphate from different sources, the evidence linking excessive phosphate intake to kidney damage in animal models and humans as well as the exceedance of the current ADI in children. Moreover, the SKLM identified data gaps and research needs that should be addressed to improve the risk assessment of phosphate, with a special focus on vulnerable population groups. Based on the presented evidence, the Commission concludes that excessive dietary phosphate intake warrants further attention regarding possible health effects in vulnerable population groups or at exposure levels exceeding the ADI. Finally, the SKLM suggests a battery of risk management measures to reduce dietary exposure to phosphate, particularly in infants, toddlers and children, and to protect patients with chronic renal diseases
What renewable energy future should we strive for? Assessing renewable energy utopias through Sci-Fi and normative energy ethics
No full textBackground
Socio-technical imaginaries, visions and utopias concerning energy and sustainability offer ideas about how the world should be. As such, they are normative endeavors that require a critical ethical assessment. However, normative assumptions about energy futures often remain implicit, thereby escaping critical scrutiny. This study combines science fiction and normative energy ethics to evaluate competing visions of renewable energy futures. We introduce a conceptual framework that distinguishes between the two main ways in which energy intersects with utopian futures: energy abundance and energy sufficiency. Next, we identify the ethical pros and cons of energy abundance and sufficiency as desirable future states, examining this through popular science fiction texts and normative energy ethics perspectives such as energy justice, virtue ethics, and critical theory of technology.
Results
The vision of renewable energy abundance provides a very appealing prospect and can motivate different stakeholders to speed up the transition to a low-carbon energy system. However, striving towards such an energy utopia comes with several caveats. First, the idea of renewable energy abundance in the near future is dangerous because it is, so far, a technological illusion. Second, regional visions of energy abundance often neglect global and intergenerational energy justice considerations. Third, according to virtue ethics, pursuing energy abundance can be considered excessive, not virtuous and hence immoral. Fourth, energy abundance can lead to problematic forms of alienation and, therefore, dystopian versions of the good life. Utopias based on renewable energy and sufficiency aim to avoid these issues. Yet they face two additional problems that seem to hinder the adoption of energy sufficiency as the leading energy policy paradigm. First, there is a real danger that citizens would protest and slow down the energy transition if energy sufficiency were to be promoted by governments on a large scale. Second, in practice, the lines between energy sufficiency and abundance, and between energy needs and wants, remain unclear and highly contextual, leading to philosophical and practical problems.
Conclusions
We propose distinguishing between two questions that may require different answers: Firstly, what kind of energy future do we, as a society, want? And what energy future should we strive for in our energy policies? Taking critiques of the pursuit of renewable energy abundance seriously, we conclude that we should resist the tendency to unquestioningly incorporate utopian ideas of renewable energy abundance into energy policies and technologies, despite the strong rhetorical appeal of abundance. This implies that the second concern regarding energy sufficiency — namely, its ambiguity, context dependency, and challenging measurement issues — should be addressed directly instead of being avoided. Energy policies must engage more explicitly with the normative assumptions underlying desirable energy futures, particularly with regard to sufficiency versus abundance
Groundwater and geothermal archetypes in Berlin, Germany
No full textUrban aquifers are influenced by several natural and anthropogenic factors, such as geological and hydrogeological conditions and built infrastructure, such as heated basements, underground car parks, and train tunnels. Realistic 3D city-scale physics-based models of complex and heterogeneous aquifers must balance accuracy and efficiency to support scenario-based subsurface management. Hence, this study aims to provide an overview of the 3D thermal state of the urban subsurface of Berlin, Germany, with the goal of identifying groundwater and geothermal archetypes. Based on a detailed 3D geological model, covering an area of 118 km2 and a depth of 250 m, block-divided (500 m × 500 m × 50 m), steady-state groundwater flow and heat transport models are created. These block models serve as a basis for identifying groundwater archetypes representing areas with similar hydrogeological and infrastructure conditions. The simulated, large-scale groundwater temperature patterns are generally in good agreement with interpolated temperatures from depth-oriented measurements. In addition, the block-scale models capture thermal hot spots and low spots that are not detected by interpolated maps. Using regression-based decision trees, 38 groundwater archetypes are identified for the shallow anthropogenically influenced layer of blocks and 21 archetypes at deeper layers (> 50 m bgl). Heated basements and groundwater head difference are the most contributing features in differentiating archetypes for the shallow layer of the blocks, while lower temperature boundary dominates selection of archetypes in deeper layers. Similarity of large-scale groundwater temperature patterns across different numbers of selected archetypes shows the robustness of the approach. Using thermal and geological criteria, 10 of the identified archetypes are classified as geothermal archetypes that indicate suitable conditions for ground source heat pump systems. The archetypes approach could be further developed to support other groundwater and subsurface uses, e.g., by considering groundwater-dependent ecosystems, legal aspects (e.g., groundwater contamination), and the interactions between different use
Photoredox Catalytic Hydropentafluorosulfanylation of Alkynes by Sulfur Hexafluoride
No full textThe interest in organic compounds bearing the pentafluorosulfanyl (SF) group has increased significantly. The photocatalytic utilization of the cheap and nontoxic sulfur hexafluoride (SF) as an SF-donating motif is an extremely valuable and still underdeveloped pathway in comparison to the well-established methodology employing the highly toxic SFCl gas. However, due to the high stability and associated low redox potential of SF, paired with the ambiphilicity of the SF radical, the development of catalytic systems to gain SF-bearing organic molecules from SF is particularly challenging. We hereby present the first photocatalytic hydropentafluorosulfanylation of aryl acetylenes by SF using Ir(ppy) as a visible-light photoredox catalyst and Hantzsch ester as a sacrificial reductant as well as a hydrogen atom transfer (HAT) reagent. The method delivers the corresponding pentafluorosulfanylated alkenes in good to excellent yields
Assessing maximum oxygen uptake through a motor-cognitive reactive agility test in team ball sports athletes
No full textBackground: Conventional laboratory and field tests often underestimate VO2max and fail to reflect the reactive agility, multidirectional demands of team ball sports. This study examined whether a motor-cognitive Reactive Agility (RA) Test can elicit a true VO2max response and serve as a sport-specific alternative for assessing VO2max in team sport athletes.
Method: Fifty-three team ball sports athletes performed an exhaustive incremental treadmill test and a motor-cognitive RA Test. The RA Test was performed on the SKILLCOURT and contained four all-out reactive agility runs of 150 m with an intermittent break of 30 s. VO2max was determined in both tests using a portable gas analyzer. Dependent t-tests, Blant-Altman analysis, concordance correlation coefficient (CCC), intraclass correlation coefficient (ICC) and correlation analyses were performed.
Results: The mean difference in VO2max between the tests was 0.25 mL × kg−1 × min−1 (0.5%, p = 0.55) with upper and lower 95% limits of agreement at 6.02 (11%) and −5.53 (10%) mL × kg−1 × min−1, respectively. CCC (pc = 0.94), ICC (0.943) and correlation analysis (r = 0.94) revealed a strong agreement and relation between VO2max in the treadmill and RA Test.
Conclusion: The RA Test reliably elicits a true VO2max response and offers a valid and more sport-specific option when compared to laboratory treadmill assessment for measuring VO2max in team ball sport athletes
