bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Flame-Film Cooling Interactions With an Academic Test Rig and Optical Laser Diagnostics
Authors: Petit Sylvain , Quevreux Benjamin , Morin Romain , Guillot Romain , Grisch Frédéric , Xavier Pradip 
Published: October 2022

Abstract
The development of lighter low-carbon technologies in the aviation sector raises a technological challenge regarding material durability and wall thermal management. This study aims to introduce a new optically accessible test rig to investigate the interaction between a premixed CH4/air turbulent flame and a parietal cooling air film for various blowing ratios. Laser Doppler velocimetry (LDV) is implemented to measure the cooling air and the mainstream inflow conditions. The impact of the blowing ratio on the mean flame topology is conducted with OH* chemiluminescence. Results show that the flame-wall distance increases with the blowing ratio and eventually reach a plateau, while the flame length constantly decreases. OH Planar-laser induced fluorescence (OH-PLIF) and phosphor thermometry (PT) are performed to assess the near-wall flame structure and the cooling effectiveness. The flame seems to be aerodynamically controlled while the cooled-air momentum has a beneficial impact on the wall temperature.
Numerical Investigation of the Local Thermo-Chemical State in a Thermo-Acoustically Unstable Dual Swirl Gas Turbine Model Combustor
Authors: Karpowski T. Jeremy P. , Ferraro Federica , Steinhausen Matthias , Popp Sebastian , Arndt Christoph M. , Kraus Christian , Bockhorn Henning , Meier Wolfgang , Hasse Christian 
Published: October 2022

Abstract
In this work, the thermo-acoustic instabilities of a gas turbine model combustor, the so-called SFB606 combustor, are numerically investigated using Large Eddy Simulation (LES) combined with tabulated chemistry and Artificial Thickened Flame (ATF) approach. The main focus is a detailed analysis of the thermo-acoustic cycle and the accompanied equivalence ratio oscillations and their associated convective time delay. In particular, the variations of the thermo-chemical state and flame characteristics over the thermo-acoustic cycle are investigated. For the operating point flame B (Pth = 25kW, Φ = 0.7), the burner exhibits thermo-acoustic instabilities with a dominant frequency of 392 Hz, the acoustic eigenmode of the inner air inlet duct. These oscillations are accompanied by an equivalence ratio oscillation, which exhibits a convective time delay between the injection in the inner swirler and the flame zone. Two LES, one adiabatic and one accounting for heat losses at the walls by prescribing the wall temperatures from experimental data and Conjugated Heat Transfer (CHT) simulations, are conducted. Results with the enthalpy-dependent table are found to predict the time-averaged flow field in terms of velocity, major species, and temperature with higher accuracy than in the adiabatic case. Further, they indicate, that heat losses should be accounted for to correctly predict the flame position. Subsequently, the thermo-chemical state variations over the thermo-acoustic cycle for the enthalpy-dependant case are analyzed in detail and compared with experimental data in terms of phase-conditioned averaged profiles and conditional averages. An overall good prediction is observed, although an overestimation of the oscillation amplitude yields a slight over-prediction of the velocity field in the low-pressure phases. The results provide a detailed quantitative analysis of the thermo-acoustic feedback mechanism of this burner.
Power Flow Optimization for a Hybrid-Electric Propulsion System
Authors: Papadopoulos Konstantinos I. , Nasoulis Christos P. , Ntouvelos Elissaios G. , Gkoutzamanis Vasilis G. , Kalfas Anestis I. 
Published: October 2022

Abstract
The present study deals with the optimization of performance for a hybrid-electric propulsion system. It focuses on the modeling and power management frameworks, while evaluation is done on a single flight basis. The main objective is to extract the maximum out of the novel powertrain archetype. Two hybridization factors are considered. The pair helps to describe the degree of hybridization at the power supply and power consumption levels. Their revised mathematical definition facilitates a unique method of hybrid-electric propulsion system modeling, that maximizes the conveyed amount of information. An in-house computational tool is developed. It employs a genetic algorithm optimizer in the interest of managing power usage during flight. Energy consumption is set as the objective function. The operation of a 19-seater, commuter aircraft is investigated. Turbo-electric, series-hybrid, parallel-hybrid and series-parallel variants are derived from a generic composition. An analysis on their optimized performance, with different technological readiness levels for 2020 and 2035, is aimed at identifying where each system performs best. Considering 2020 technology, it does not yield a viable hybrid-electric configuration, without suffering significant payload penalties. Architectures relying on mechanical propulsors show promise of 15% reduction to energy consumption, accounting for 2035 readiness levels. The concepts of Boundary Layer Ingestion and Distributed Propulsion display the potential to boost electrified propulsion. The series-hybrid and series-parallel configurations are the primary beneficiaries of these concepts, displaying up to 30% reduction in fuel and 20% reduction in energy consumption.
Impacts of the Additive Manufacturing Process on the Roughness of Engine Scale Vanes and Cooling Channels
Authors: Wildgoose Alexander J. , Thole Karen A. , Subramanian Ramesh , Kersting Lisa , Kulkarni Anand 
Published: October 2022

Abstract
By leveraging the additive manufacturing platform, development time and costs for turbine component testing can be reduced relative to traditional investment casting. Surface roughness is a key characteristic of the additive manufacturing process that can impact flow, heat transfer, and mechanical integrity of printed components. There are multiple design and build considerations that result in variability in surface roughness especially when additively fabricating complicated three-dimensional vanes and internal cooling passages. This study characterizes the surface roughness of internal cooling passages, vanes, and flat external surface samples made using additive manufacturing, specifically the direct metal laser sintering process. The samples were manufactured with various wall thicknesses, layer thicknesses, build locations, build directions, and on different AM machines. A combination of computed tomography scanning and optical profilometry were used to evaluate surface roughness levels. The data indicates that the dominate factors in roughness for a given layer thickness are a function of wall thickness, build location, and build direction.
Flame Response of a Lean Premixed Swirl Flame to High Frequency Azimuthal Forcing
Authors: Mangold Tobias O. , Orchini Alessandro , Paschereit Christian Oliver , Moeck Jonas P. , Bohon Myles D. 
Published: October 2022

Abstract
This experimental study explores fundamental qualitative differences of the response of a lean-premixed turbulent swirl flame to azimuthal acoustic excitation in the low- (LF), medium- (MF), and high-frequency (HF) regime. An experimental test rig with a cylindrical combustion chamber is equipped with an array of azimuthally distributed acoustic driver outlets in the burner front plate, allowing for the excitation of the flame with a longitudinal wave, and different azimuthal wave types. Phase-averaged chemiluminescence images show that in the LF regime the flame responds to both longitudinal and azimuthal forcing schemes with hydrodynamically induced intensity fluctuation patterns at relatively small wavelength. Azimuthal forcing generates helical intensity patterns, at the same wavelengths but with lower intensities compared to longitudinal forcing. A fundamentally different flame response is observed in the HF regime: Longitudinal forcing generates only a very weak flame response, and the amplitude of the flame response to azimuthal forcing type depends on the forced azimuthal mode. No hydrodynamic structures are evident anymore, but the flame response now uniformly covers each of the flame sides, indicating a purely acoustic response.
The Road to a Digital Twin for Fan-Blade Off and Thermally Enabled Structural Analyses of Aero Engines
Authors: Keskin Akin , Fox Rob 
Published: October 2022

Abstract
Digital Twin is not a buzz word anymore and started to become reality in many industrial applications. The Digital Twin concept does allow design, analysis, test, manufacturing and service data to be merged more closely together to provide an additional value stream for the industry which can help in better product definition, reduced time-to-market, reduced development cost, understanding of in-service events and predictions of product behaviours based on service data. Over the last decade Rolls-Royce has been working to use high-fidelity simulations models together with test data to create models that can be used more in predictive modes to support expensive physical tests and ultimately replace those with cheaper and more flexible computer models.
The paper is going to discuss the journey taken to utilize a Digital Twin of an aero engine to support safety assessment of fan-blade off events but also how the same concept can be used to create a thermally enabled structural model to assess component movements under changing operating conditions with the aim to optimize design. Both Digital Twin models can be of much use in the design, certification but also services phase to understand behaviour and characteristics of the product and its individual sub-modules. The presented work will focus on the model creation aspect, the emphasis into the required accuracy of each modelling step and the link between test and design data for a more seamlessly integration of multiple disciplines. The paper will include a comparison of simulation and test data and will discuss areas of alignment and misalignment and the conclusion that need to be drawn.
Furthermore the paper will depict areas of research needed to improve simulation capability, the importance of close collaboration between industry, academia and authorities, and the significance in having a cross-functional team with experts from various disciplines to contribute to the model set up, run and post-processing to maximize the insight.
Gas Turbine Secondary Air Systems Modeling
Authors: Kocagul Mustafa , Arıkan A. Cihat , Uyav Omer , Ertas Avni , Bruns James , Jayanthi Aditya 
Published: October 2022

Abstract
Modern gas turbine engine designers are challenged with aggressive power, cycle efficiency and operational life requirements. Those targets are directly related with turbine inlet temperature, material selection and design choices. Increasing turbine inlet temperature, increases cycle efficiency and power output; however, operational life is adversely affected. To optimize these contradicting targets, cooling and sealing design choices must be carefully selected, which is the main responsibility of Secondary Air Systems design engineer.
Altair Flow Simulator© (FS) is an integrated one-dimensional flow, thermal, and combustion modeling software that can be used for conceptual as well as detailed design and analysis for any thermo-fluid system design application.
This paper reviews the FS modeling methods that are commonly used for SAS design. The methods to be reviewed include rotating orifice, rotor-stator cavity, and labyrinth seals. The component modeling results are validated by comparing literature test data, company owned test data, and Computational Fluid Dynamics (CFD) analysis. Discharge coefficients for orifices, swirl ratio for rotating cavities and leakage values for smooth-land labyrinth seals are investigated throughout the paper.
Paleoproterozoic Earth and the transition toward modern tectonic processes: A synopsis
Authors: Corrigan* D. , Van Rooyen D. 
Published: October 2022

ABSTRACT
Many of the hallmarks of modern plate-tectonic processes first occurred in the Paleoproterozoic Era, indicating that the mechanical, thermal, and compositional parameters of Earth’s lithosphere had evolved to approximately modern ranges of values by that time. The core of Laurentia preserves widespread examples of both convergent and divergent tectonic processes in the time span from 2.2 to 1.7 Ga, particularly within the Trans-Hudson composite orogen. Large continental masses or supercontinents previously accreted during the Neoarchean Era began to break up between 2.4 and 2.0 Ga, leading to the deposition of widespread passive-margin sedimentary prisms and locally voluminous emplacement of mafic magma in radiating dike swarms. Further rifting and drifting led to the formation of incipient (e.g., Bravo Formation) to fully developed oceanic crust (e.g., Manikewan Ocean). Plate convergence beginning ca. 1.92 Ga heralded the demise of the Manikewan Ocean ~150 m.y. after its postulated opening. Protracted subduction of oceanic lithosphere over a period of ~90 m.y. produced a series of island arcs, some of which (Lynn Lake, Flin Flon, Snow Lake) host world-class volcanogenic massive sulfide (VMS) ± Au deposits. Plate convergence also led to progressive southeastward (present-day coordinates) accretion of microplates on a pre-amalgamated core consisting of the Slave craton and the Rae and Hearne “Provinces,” forming the Churchill plate. Following the formation of the Churchill plate collage ca. 1.86 Ga, subduction of oceanic lithosphere organized along an ~4000-km-long, north-dipping subduction zone along the southeastern edge of the Churchill plate, producing voluminous continental arc magmas in an Andean-type setting. The final phase of tectonic evolution involved collision of the Superior and North Atlantic cratons with the Churchill plate and intervening juvenile oceanic arc terranes. That phase was strongly influenced by the irregular shape of the indenting Superior craton, favoring the development of oroclines and leading to escape tectonics and lateral extrusion of continental microplates. For the most part, the Trans-Hudson was a hot but not necessarily thick orogen, perhaps reflecting a higher geothermal gradient during the Paleoproterozoic Era.
Changes in the growth of very preterm infants in England 2006–2018
Authors: Young Aneurin , Cole Tim J , Cheng Guo , Ennis Sarah , Beattie R Mark , Johnson Mark John 
Published: October 2022

ObjectiveTo compare weight gain from birth to term equivalent age in very preterm infants in England born during two eras (2006–2011 and 2014–2018); to assess demographic and care factors influencing weight gain.MethodsData for infants born before 32 weeks of gestation during 2014–2018 in England were obtained (29 687 infants). Weight gain modelled using SuperImposition by Translation And Rotation (SITAR), with infants grouped by gestational week. A cohort from 2006 to 2011 was used for comparison (3288 infants). Multiple linear regression was used to assess factors influencing change in weight SD score from birth to 36 weeks postmenstrual age.ResultsWeight gain velocity (termed ‘intensity’ in SITAR models) was greater in the more recent cohort for all gestation groups born before 30 weeks of gestation. After adjustment for gestation, birth weight and other perinatal factors, care elements associated with faster weight gain included delivery in a level 3 unit (0.09 SD less weight gain deficit, 95% CI: 0.07 to 0.10) and parenteral nutrition initiation during the first day of life (0.08 SD, 95% CI: 0.06 to 0.10). Factors associated with slower weight gain included early ventilation (−0.07 SD, 95% CI: −0.08 to −0.05) and less deprived neighbourhood (−0.012 SD per Index of Multiple Deprivation decile, 95% CI: −0.015 to −0.009).ConclusionsWeight gain for extremely preterm infants was faster during 2014–2018 than during 2006–2011. Early initiation of parenteral nutrition and birth in a level 3 unit may contribute to faster weight gain.
Nasal high-flow therapy to Optimise Stability during Intubation: the NOSI pilot trial
Authors: Foran Jason , Moore Carmel Maria , Ni Chathasaigh Caitriona M , Moore Shirley , Purna Jyothsna R , Curley Anna 
Published: October 2022

ObjectiveIn adult patients with acute respiratory failure, nasal high-flow (NHF) therapy at the time of intubation can decrease the duration of hypoxia. The objective of this pilot study was to calculate duration of peripheral oxygen saturation below 75% during single and multiple intubation attempts in order to inform development of a larger definitive trial.Design and settingThis double-blinded randomised controlled pilot trial was conducted at a single, tertiary neonatal centre from October 2020 to October 2021.ParticipantsInfants undergoing oral intubation in neonatal intensive care were included. Infants with upper airway anomalies were excluded.InterventionsInfants were randomly assigned (1:1) to have NHF 6 L/min, FiO21.0 or NHF 0 L/min (control) applied during intubation, stratified by gestational age (<34 weeks vs ≥34 weeks).Main outcome measuresThe primary outcome was duration of hypoxaemia of <75% up to the time of successful intubation,Results43 infants were enrolled (26 <34 weeks and 17 ≥34 weeks) with 50 intubation episodes. In infants <34 weeks’ gestation, median duration of SpO2of <75% was 29 s (0–126 s) vs 43 s (0–132 s) (p=0.78, intervention vs control). Median duration of SpO2 of<75% in babies ≥34 weeks’ gestation was 0 (0–32 s) vs 0 (0–20 s) (p=0.9, intervention vs control).ConclusionThis pilot study showed that it is feasible to provide NHF during intubation attempts. No significant differences were noted in duration of oxygen saturation of <75% between groups; however, this trial was not powered to detect a difference. A larger, higher-powered blinded study is warranted.
Do adolescents with impaired vision have different intentions and ambitions for their education, career and social outcomes compared to their peers? Findings from the Millennium Cohort Study
Authors: Horvat-Gitsels Lisanne A , Cortina-Borja Mario , Rahi Jugnoo S 
Published: October 2022

Background/aimsTo investigate if impaired vision adversely impacts the intentions/ambitions of adolescents concerning their future education, careers and social outcomes.MethodsPopulation-based birth cohort study in the UK comprising 9273 participants from the Millennium Cohort Study who were followed up to age 17 years. Children were classified as having normal vision or unilateral or bilateral impaired vision caused by significant eye conditions based on detailed parental-structured questionnaire data on sight problems and treatment coded by clinicians. Ten domains covering education, career and social outcomes by age 30 were investigated.ResultsAdjusted regression models showed few differences by vision status. Bilateral impaired vision was associated with increased odds of intending to remain in full-time education after statutory school age (adjusted OR (aOR) 2.00, 95% CI 1.08 to 3.68) and of home ownership at age 30 (aOR 1.83, 95% CI 1.01 to 3.32). Impaired vision was not associated with intending to attend university. A significantly higher proportion of parents of children with bilateral or unilateral impaired vision thought that their child would not get the exam grades required to go to university than parents of those with normal vision (29% or 26% vs 16%,p=0.026).ConclusionAdolescents with impaired vision have broadly the same intentions/ambitions regarding future education, careers and social outcomes as their peers with normal vision. The known significant gaps in attainment in these domains among young adults with vision impairment are therefore likely to be due to barriers that they face in achieving their ambitions. Improved implementation of existing interventions is necessary to ensure equality of opportunities.
Targeting cathepsin B by cycloastragenol enhances antitumor immunity of CD8 T cells via inhibiting MHC-I degradation
Authors: Deng Guoliang , Zhou Lisha , Wang Binglin , Sun Xiaofan , Zhang Qinchang , Chen Hongqi , Wan Ning , Ye Hui , Wu Xiaoqi , Sun Dongdong , Sun Yang , Cheng Haibo 
Published: October 2022

BackgroundThe loss of tumor antigens and depletion of CD8 T cells caused by the PD-1/PD-L1 pathway are important factors for tumor immune escape. In recent years, there has been increasing research on traditional Chinese medicine in tumor treatment. Cycloastragenol (CAG), an effective active molecule inAstragalus membranaceus, has been found to have antiviral, anti-aging, anti-inflammatory, and other functions. However, its antitumor effect and mechanism are not clear.MethodsThe antitumor effect of CAG was investigated in MC38 and CT26 mouse transplanted tumor models. The antitumor effect of CAG was further analyzed via single-cell multiomics sequencing. Target responsive accessibility profiling technology was used to find the target protein of CAG. Subsequently, the antitumor mechanism of CAG was explored using confocal microscopy, coimmunoprecipitation and transfection of mutant plasmids. Finally, the combined antitumor effect of CAG and PD-1 antibodies in mice or organoids were investigated.ResultsWe found that CAG effectively inhibited tumor growth in vivo. Our single-cell multiomics atlas demonstrated that CAG promoted the presentation of tumor cell-surface antigens and was characterized by the enhanced killing function of CD8+T cells. Mechanistically, CAG bound to its target protein cathepsin B, which then inhibited the lysosomal degradation of major histocompatibility complex I (MHC-I) and promoted the aggregation of MHC-I to the cell membrane, boosting the presentation of the tumor antigen. Meanwhile, the combination of CAG with PD-1 antibody effectively enhanced the tumor killing ability of CD8+T cells in xenograft mice and colorectal cancer organoids.ConclusionOur data reported for the first time that cathepsin B downregulation confers antitumor immunity and explicates the antitumor mechanism of natural product CAG.
An Exact Solution Method for the Political Districting Problem
Authors: Chopra Sunil , Park Hyunwoo , Shim Sangho 
Published: October 2022

Mehrotra, Johnson, and Nemhauser (1998) [Management Science 44, pp. 1100–1114] addressed a problem for political districting and developed an optimization based heuristic to find good districting plans which partition the population units into contiguous districts with equal populations. Their case study found a good South Carolina plan at a penalty cost of 68. This paper develops a strong integer programming model identifying the exact optimal solution. Our model identifies the optimal South Carolina plan at the minimum penalty of 64. Motivated by the 2019 lawsuit challenging the congressional plan as gerrymandering, we inspect the actual Maryland plan.