Layla wa-l-magnun = Layla und der Besessene. - Zweisprachig: Arabisch / Deutsch (Deutsche Erstausgabe)

Der ägyptischer Dichter, Dramatiker und Essayist Salah Abdassabur hat nach der ernüchternden Niederlage von 1967 in verschiedenen Werken über das Spannungsverhältnis zwischen Idealitätsverpflichtung und Verwirklichungsängsten reflektiert. Die dem Drama aus dem Jahre 1970 zugrunde liegende Legende von Magnun und Layla - die Parabel von der erfüllenden Verehrung eines an die Stelle der Realität getretenen Ideals - versinnbildlicht diesen Konflikt

Off-design performance assessment of an axial turbine for a 100 MWe concentrated solar power plant operating with CO2 mixtures

Data availability: No data was used for the research described in the article.This paper presents an investigation of the aerodynamic performance of a 130 MW axial turbine operating with a CO2/SO2 mixture using a mean-line off-design performance model; where the validity of this model has been confirmed through verification against results from the literature and computational fluid dynamic (CFD) simulations. This analysis also includes assessing the impact of varying the number of stages on the part-load operation. Additionally, the application of similitude theory to non-dimensionalise performance characteristics is validated by assessing the performance of the same turbine with different working fluids, mixture compositions, and rotational speeds. The mean-line performance model applied throughout this study is based on the Aungier loss model, whilst a multi-stage, Reynolds averaged CFD model is employed to assess the 3D flow behaviour using the − turbulence model. Significant deviations in total-to-total efficiency were observed between the mean-line and CFD results during part-load operation, especially at lower mass flow rates. These deviations can reach up to 18% when the blade Mach number exceeds the design point by 12%. This is attributed to flow separation, which is evident from the CFD simulations, and the mean-line loss model fails to predict. From a purely aerodynamic standpoint, the turbine can operate at part-load conditions up to 88.5% of the design flow coefficient based on the CFD results and achieve an efficiency of 80.2%. It was also found that increasing the number of stages from 4 to 14 can improve the off-design total-to-total efficiency by approximately 7.7% at 93% of the design flow coefficient. This demonstrates that increasing the number of stages enhances turbine performance at both design and part-load operations. Finally, the similitude scaling laws formulated using real-gas equation of state were found to remain valid for all the mixtures, molar compositions, and operating conditions considered.European Union’s Horizon 2020 research and innovation programme under grant agreement No. 814985

A Modified Loss Breakdown Approach for Axial Turbines Operating With Blended Supercritical Carbon Dioxide

Paper No: GTP-22-1616In this paper, a modified loss breakdown approach is introduced for axial turbines operating with supercritical carbon dioxide (sCO2) mixtures using computational fluid dynamics (CFD) results. Loss breakdown analysis has been previously developed using two approaches, however each approach has its own uncertainties. The first approach neglects the effects of the cross-interaction between the different loss sources, while the second approach ignores the potential changes to the boundary layer thicknesses and the loss source domains. Although the second methodology accounts for the interactions between the different loss sources, it may produce less accurate predictions for compact machines like sCO2 turbines where the boundary layer may dominate the flow passage. The proposed methodology aims to obtain the turbine loss breakdown using a single CFD model where all sources of aerodynamic loss coexist, while considering variable loss regions defined based on the velocity and entropy distribution results. A steady-state, single-stage, single-passage, three-dimensional numerical model is setup to simulate the turbine and verify the loss audit methodology. The results are verified against the published loss audit methodologies for a 130 MW axial turbine operating with CO2/C6F6 blend, designed using an in-house mean line design code. The results show a good agreement between the proposed approach and the multiple-model approaches from the literature. However, the existing approaches appear to overestimate endwall losses by 13–16% and underestimate the profile losses by 11–31% compared to the proposed approach. Compared to the Aungier mean line loss model, large differences in loss sources are observed from the CFD results, especially for the stator and rotor endwall losses which are found to be 3.2 and 1.6 times the CFD values, respectively. This helps to indicate limitations in existing mean line loss models.European Union’s Horizon 2020 Research and Innovation Programme (Grant No. 814985; Funder ID: 10.13039/100010661)

Design of a 130 MW Axial Turbine Operating with a Supercritical Carbon Dioxide Mixture for the SCARABEUS Project

Data Availability Statement: Data supporting this study are available on request. Please contact the corresponding author.This manuscript is an extended version of our paper published in the Proceedings of the 15th European Turbomachinery Conference, Budapest, Hungary, 24–28 April 2023.Supercritical carbon dioxide (sCO2) can be mixed with dopants such as titanium tetrachloride (TiCl4), hexafluoro-benzene (C6F6), and sulphur dioxide (SO2) to raise the critical temperature of the working fluid, allowing it to condense at ambient temperatures in dry solar field locations. The resulting transcritical power cycles have lower compression work and higher thermal efficiency. This paper presents the aerodynamic flow path design of a utility-scale axial turbine operating with an 80–20% molar mix of CO2 and SO2. The preliminary design is obtained using a mean line turbine design method based on the Aungier loss model, which considers both mechanical and rotor dynamic criteria. Furthermore, steady-state 3D computational fluid dynamic (CFD) simulations are set up using the k-ω SST turbulence model, and blade shape optimisation is carried out to improve the preliminary design while maintaining acceptable stress levels. It was found that increasing the number of stages from 4 to 14 increased the total-to-total efficiency by 6.3% due to the higher blade aspect ratio, which reduced the influence of secondary flow losses, as well as the smaller tip diameter, which minimised the tip clearance losses. The final turbine design had a total-to-total efficiency of 92.9%, as predicted by the CFD results, with a maximum stress of less than 260 MPa and a mass flow rate within 1% of the intended cycle’s mass flow rate. Optimum aerodynamic performance was achieved with a 14-stage design where the hub radius and the flow path length are 310 mm and 1800 mm, respectively. Off-design analysis showed that the turbine could operate down to 88% of the design reduced mass flow rate with a total-to-total efficiency of 80%.European Union’s Horizon 2020 research and innovation programme under grant agreement No. 814985. Funder ID: 10.13039/100010661

Prospecting environmental mycobacteria: combined molecular approaches reveal unprecedented diversity

Background: Environmental mycobacteria (EM) include species commonly found in various terrestrial and aquatic environments, encompassing animal and human pathogens in addition to saprophytes. Approximately 150 EM species can be separated into fast and slow growers based on sequence and copy number differences of their 16S rRNA genes. Cultivation methods are not appropriate for diversity studies; few studies have investigated EM diversity in soil despite their importance as potential reservoirs of pathogens and their hypothesized role in masking or blocking M. bovis BCG vaccine. Methods: We report here the development, optimization and validation of molecular assays targeting the 16S rRNA gene to assess diversity and prevalence of fast and slow growing EM in representative soils from semi tropical and temperate areas. New primer sets were designed also to target uniquely slow growing mycobacteria and used with PCR-DGGE, tag-encoded Titanium amplicon pyrosequencing and quantitative PCR. Results: PCR-DGGE and pyrosequencing provided a consensus of EM diversity; for example, a high abundance of pyrosequencing reads and DGGE bands corresponded to M. moriokaense, M. colombiense and M. riyadhense. As expected pyrosequencing provided more comprehensive information; additional prevalent species included M. chlorophenolicum, M. neglectum, M. gordonae, M. aemonae. Prevalence of the total Mycobacterium genus in the soil samples ranged from 2.3×107 to 2.7×108 gene targets g−1; slow growers prevalence from 2.9×105 to 1.2×107 cells g−1. Conclusions: This combined molecular approach enabled an unprecedented qualitative and quantitative assessment of EM across soil samples. Good concordance was found between methods and the bioinformatics analysis was validated by random resampling. Sequences from most pathogenic groups associated with slow growth were identified in extenso in all soils tested with a specific assay, allowing to unmask them from the Mycobacterium whole genus, in which, as minority members, they would have remained undetected

Global Influenza Seasonality: Reconciling Patterns across Temperate and Tropical Regions

Bac k g r o u n d: Despite the significant disease burden of the influenza virus in humans, our understanding of the basis for its pronounced seasonality remains incomplete. Past observations that influenza epidemics occur in the winter across temperate climates, combined with insufficient knowledge about the epidemiology of influenza in the tropics, led to the perception that cool and dry conditions were a necessary, and possibly sufficient, driver of influenza epidemics. Recent reports of substantial levels of influenza virus activity and well-defined seasonality in tropical regions, where warm and humid conditions often persist year-round, have rendered previous hypotheses insufficient for explaining global patterns of influenza. Objectiv e: In this review, we examined the scientific evidence for the seasonal mechanisms that potentially explain the complex seasonal patterns of influenza disease activity observed globally. Me t h o d s: In this review we assessed the strength of a range of hypotheses that attempt to explain observations of influenza seasonality across different latitudes and how they relate to each other. We reviewed studies describing population-scale observations, mathematical models, and ecological, laboratory, and clinical experiments pertaining to influenza seasonality. The literature review includes studies that directly mention the topic of influenza seasonality, as well as other topics w

Effect of Composition on Electrical and Optical Properties of Thin Films of Amorphous GaxSe100−x Nanorods

We report the electrical and optical studies of thin films of a-GaxSe100−x nanorods (x = 3, 6, 9 and 12). Thin films of a-GaxSe100−x nanorods have been synthesized thermal evaporation technique. DC electrical conductivity of deposited thin films of a-GaxSe100−x nanorods is measured as a function of temperature range from 298 to 383 K. An exponential increase in the dc conductivity is observed with the increase in temperature, suggesting thereby a semiconducting behavior. The estimated value of activation energy decreases on incorporation of dopant (Ga) content in the Se system. The calculated value of pre-exponential factor (σ0) is of the order of 101 Ω−1 cm−1, which suggests that the conduction takes place in the band tails of localized states. It is suggested that the conduction is due to thermally assisted tunneling of the carriers in the localized states near the band edges. On the basis of the optical absorption measurements, an indirect optical band gap is observed in this system, and the value of optical band gap decreases on increasing Ga concentration

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112