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A review of existing research on signatures of gas turbine faults is presented. Faults that influence the aerothermodynamic performance of compressors and turbines, such as fouling, tip clearance increase, erosion, variable geometry system malfunction, and object impact damage, are covered. The signatures of such faults, which are necessary for establishing efficient gas path diagnostic methods, are studied. They are expressed through mass flow capacity and efficiency deviations. The key characteristics of the ratio of such deviations are investigated in terms of knowledge existing in published research. Research based on experimental studies, field data, and results of detailed fluid dynamic computations that exist today is found to provide such information. It is shown that although such signatures may be believed to have a unique correspondence to the type of component fault, this is only true when a particular engine and fault type are considered. The choice of diagnostic methods by developers should, thus, be guided by such considerations instead of using values taken from the literature without considering the features of the problem at hand. [ABSTRACT FROM AUTHOR]

Objectives Patients with RA were at increased risk for COVID-19-associated hospitalization and death during the first year of the pandemic in Greece. We aimed to examine their outcomes after the SARS-Cov-2 Omicron, a more contagious but with milder clinical impacts variant, prevailed. Methods A retrospective, nationwide study was conducted between 1 January 2022 and 30 June 2022 in all RA patients under treatment and matched (1:5) on age, sex and region of domicile random general population comparators. Confirmed SARS-CoV-2 infections, hospitalizations and deaths, anti-rheumatic medications, prior COVID-19, vaccinations and anti-viral medications were recorded. Results Among 34 182 RA patients, infections (n  = 5569, 16.29%), hospitalizations (n  = 489, 1.43%) and deaths (n  = 106, 0.31%) were more frequent than among comparators. Incidence rates per 1000 person/years of infection [IRR (95% CI):1.19 (1.16, 1.23)], hospitalization [IRR (95% CI):2.0 (1.82, 2.24)], and death [IRR (95% CI):1.81 (1.44, 2.27)] were increased in RA despite better vaccination coverage (89% vs 84%) and more frequent use of anti-viral medications (2.37% vs 1.08). Logistic regression analysis after correcting for age, sex, vaccinations, prior COVID-19, and anti-viral medications in SARS-CoV-2 infected RA patients and comparators revealed increased risk of hospitalization (OR: 2.02, 95% CI: 1.79, 2.27) and death [OR: 1.73, (95% CI: 1.36, 2.20)] in RA. Among infected RA patients, rituximab treatment conferred increased risks for hospitalization [OR: 6.12, (95% CI: 2.89, 12.92)] and death [OR: 12.06 (95% CI: 3.90, 37.31)], while JAK inhibitors increased only hospitalization risk [OR: 2.18 (95% CI: 1.56, 3.06)]. Conclusion RA remains a risk factor for hospitalization and death in an era of a relatively low COVID-19 fatality rate, pointing to the need of perseverance in vaccination programs and wider use of anti-viral medications. [ABSTRACT FROM AUTHOR]

In a time when low emission solutions and technologies are of utmost importance regarding the sustainability of the aviation sector, this publication introduces a reduced-order physics-based model for combustion chambers of aeroengines, which is capable of reliably producing accurate pollutant emission and combustion efficiency estimations. The burner is subdivided into three volumes, with each represented by a single perfectly stirred reactor, thereby resulting in a simplified three-element serial chemical reactor network configuration, reducing complexity, and promoting the generality and ease of use of the model, without requiring the proprietary engine information needed by other such models. A tuning method is proposed to circumvent the limitations of its simplified configuration and the lack of detailed geometric data for combustors in literature. In contrast to most similar frameworks, this also provides the model with the ability to simultaneously predict the combustion efficiency and all pollutant emissions of interest ( N O x , C O and unburnt hydrocarbons) more effectively by means of implementing a detailed chemical kinetics model. Validation against three correlation methods and actual aeroengine configurations demonstrates accurate performance and emission trend predictions. Integrated within two distinct combustion chamber low-emission preliminary design processes, the proposed model evaluates each new design, thereby displaying the ability to be employed in terms of optimizing a combustor's overall performance given its sensitivity to geometric changes. Overall, the proposed model proves its worth as a reliable and valuable tool for use towards a greener future in aviation. [ABSTRACT FROM AUTHOR]

A method is presented for optimizing burnt fuel and flight time of civil aircraft missions, under the scope of a full-scale free route airspace implementation as well as usage of actual environmental data, focusing on ambient temperature and pressure. A computational analysis model, using online available aircraft data is considered, for flight envelopes defined by the user, is used as the base tool. The model is validated over real flight data, before it is used as the main tool for optimization of flight missions. Flight paths are analyzed by considering both their vertical and horizontal aspect. Optimal paths are derived, for each chosen mission, through an optimization process that takes advantage of the flexibilities that become available by implementation of Free Route Airspace. Vertical flight path is shown to play very important role in achieving optimal flights, while horizontal paths also offer optimality possibilities, with a strong dependence on weather conditions.

Objectives To investigate coronavirus disease 2019 (COVID-19)-associated risk of hospitalization and death in RA, AS, PsA, SLE and SSc in comparison with the general population during the first year of the pandemic, and compare their overall mortality with 2019. Methods Interlinking nationwide electronic registries, we recorded confirmed COVID-19-associated infections, hospitalizations and deaths, and all-cause deaths between 1 March 2020 and 28 February 2021 in all adults with RA, AS, PsA, SLE and SSc under treatment (n  = 74 970, median age 67.5, 51.2, 58.1, 56.2 and 62.2 years, respectively) and in random comparators from the general population matched (1:5) on age, sex and region of domicile. Deaths from all causes during 2019 were also recorded. Results Compared with the general population, incidence rates (IR) for COVID-19-associated hospitalization were higher in RA [IR ratio (IRR) 1.71(1.50–1.95)], SLE [2.0 (1.4–2.7)] and SSc [2.28 (1.29–3.90)], while COVID-19-associated death rates were higher in RA [1.91 (1.46–2.49)]. When focusing only on severe acute respiratory syndrome coronavirus 2–infected subjects, after adjusting for age and gender, the odds ratio for COVID-19 associated death was higher in RA [1.47 (1.11–1.94)] and SSc [2.92 (1.07–7.99)] compared with the general population. The all-cause mortality rate compared with the general population increased in RA during the first year of the pandemic (IRR 0.71) with reference to 2019 (0.59), and decreased in SSc (IRR 1.94 vs 4.36). Conclusion COVID-19 may have a more severe impact in patients with systemic rheumatic disease than in the general population. COVID-19-related mortality is increased in subgroups of patients with specific rheumatic diseases, underscoring the need for priority vaccination and access to targeted treatments. [ABSTRACT FROM AUTHOR]

An integrated turbocharger 1D design tool, allowing retrofit of both compressor and turbine is presented. An optimization procedure is employed, to design both compressor and turbine to match the entire turbocharged system in an optimal way. The optimization process focuses on engine specific fuel consumption reduction in the engine range of operation, while ensuring appropriate matching between turbomachinery components and the diesel engine. Structural integrity of both turbo-components is ensured by using simplified structural and modal analysis. Dimensionless parameters are used as optimization variables, for both compressor and turbine, allowing the design process to become fully automatic. The platform produces four optimal 1D geometries, of different possible centrifugal compressor diffuser and turbine combinations. The combination that gives the best improvement to the diesel engine operation is identified. A case study is presented, where all four turbocharger configurations are designed and analyzed aiming to at least recover the original diesel engine performance. The platform then sorts all four optimized turbocharger geometries based on annual fuel cost reduction. The best configuration achieves the largest fuel consumption reduction (0.4% for the case presented), while stable operation and structural integrity are ensured. Additionally, a study of how the new machine learning volute loss models affect the designed geometry is performed. Finally, a techno-economical assessment is performed in order to identify the most profitable retrofit option, turbocharger redesign being one of four possible turbocharger options considered by the authors. Redesigning the entire turbocharger is shown to provide the largest long term profit. [ABSTRACT FROM AUTHOR]

Background: Drug persistence is a crucial aspect of treatment success in psoriasis., Objectives: The scope of this manuscript is to record real-world evidence concerning drug survival of biologic agents used for psoriasis treatment and to detect associated modifying factors in Greece., Methods: This was a retrospective cohort study based on data extracted from the nationwide Greek prescription system. Psoriatic patients, with or without concomitant psoriatic arthritis (PsA), that had initiated biologics between January 1st 2016 and December 31st 2020 were included., Results: We included 8,819 patients who received 13,359 treatment lines. Among them, 76.8% were biologic naïve patients and 16.5% were diagnosed with concomitant PsA. The overall median drug survival was 34.3 (95% CI: 32.6-36.5) months. Drug persistence at 12, 24, 36 and 48 months of follow-up was 71.9%, 57.7%, 49.0% and 43.7%, respectively. Patients receiving brodalumab had the highest drug survival rate in the first two years, while secukinumab had the highest rates beyond this period. Overall, drug survival rates were higher in the 1st [median, 51.1 (95% CI: 47.1, not reached (NR) months] compared to the 2nd treatment line and onwards [median, 21.7 (95% CI: 20.0, 23.5) months]. Treatment line, PsA status, age and sex were found to significantly affect drug survival rates., Conclusions: Our findings confirm previous reports regarding the importance of efficient 1st line biologics and the vulnerability of patients to co-existent PsA. The utilitzation of antibodies against interleukins confer to high drug survival rates. These results will assist clinical management of psoriasis patients in Greece., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)