bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation Method of Rotor Dynamic Characteristics Considering Temperature Distribution and Aerodynamic Load
Authors: Xiang Fengguang , Chen Xi , Zhang Bo , Ren Guangming , Gan Xiaohua 
Published: November 2022

Abstract
When operating in a high-temperature and high-pressure environment, the high-speed rotor systems of aero-engines are inevitably subjected to thermal and aerodynamic loads. However, conventional simulations and experiments of rotor dynamics did not consider temperature distribution and aerodynamic load. Therefore, it’s necessary to investigate the influence mechanism of temperature distribution and aerodynamic loads on rotor dynamics.
Using polynomial function fitting for the continuously various parameters in elements, combined with the temperature distribution, the axial distribution of physical parameters in shaft elements was established. The stiffness coefficient matrix considering temperature load was derived based on Timoshenko beam theory. By introducing the tension (compression) potential energy, the additional stiffness coefficient matrix was derived from Lagrange equation. Using state-space vector method, the differential equations of motion for rotor-support system were solved, and dynamic characteristics of rotor system subjected to temperature distribution and aerodynamic force were analyzed. The simulation method was verified with a typical fan rotor under the maximum operating condition.
The results indicate that the rotor dynamic behavior is more sensitive to temperature distribution than aerodynamic load when operating in the temperature range of 40∼190°C. And the decrease of first two critical speeds is mainly caused by thermal load. Due to the relatively low temperature, the first-order critical speed of fan rotor considering the additional load is reduced slightly, while the second-order one is decreased by 3.42%. When a mass unbalance of 500 g·mm is located at the first disk, the resonant amplitude of unbalance response rises slightly (0.25%) with additional load. If such amount of unbalance is located at the third disk, the peak amplitude is increased by 1.28%. In addition, such a simulation method could be extended to core engines or even dual- or triple-rotor engines with higher temperature and aerodynamic load, where the dynamic characteristics and unbalance responses are expected to be significantly affected.
Active Rotor Controller Design for Vibration and Bend Mitigation Utilizing Active Magnetic Bearings and Internal Shaft Actuation
Authors: Fieux Gauthier , Bailey Nicola , Keogh Patrick 
Published: November 2022

Abstract
Strategies are required to reduce vibrations in machines that use rotor systems, as these disturbances reduce the life and quality of the machine. A novel low-frequency on-board counter-bend actuator topology has been designed in order to control high frequency vibrations by taking advantage of synchronous forces from the rotating frame of a rotor supported by Active Magnetic Bearings (AMBs). The AMBs ensure in return stable contact-free levitation of the rotor. A complete model of the rotor system is established, based on a finite element representation of the rotor. The feedback control forces of the AMBs are described to account for the non-collocation of the sensor and actuation, and the PD controller gains are chosen using the sensitivity function. The lowest frequency mode of the operating range is located at 2,700 RPM, and time domain analysis shows that the application of symmetric 80 N.m counter-bend moments on the rotor coupling flanges can reduce the vibration amplitude by 88% at this rotation speed.
Dynamic Characteristics of Rotor-SFD-Support System Excited by Base Harmonic Excitations Using MHB-AFT Method
Authors: Zhang Bo , Chen Xi , Xiang Fengguang , Gan Xiaohua , Ren Guangming 
Published: November 2022

Abstract
When operating at high speed, aeroengines mounted on the aircrafts also perform complicated maneuvering flights along with the aircrafts. The engine rotor systems will undergo forced motions excited by base movements and mass unbalance, which may lead to severe vibrations. Squeeze film damper (SFD) is generally used for vibration damping in aeroengine, but it also introduces structural nonlinearity like bistable jump. Moreover, the reliability of SFD is also affected by base excitations. Therefore, it is necessary to investigate the nonlinear dynamic behavior of rotor-SFD-support system excited by base motions.
Taking a muti-disk rotor shaft supported by two SFDs with squirrel cages as the research object to simulate a gas generator in a turboshaft engine, the steady-state responses of the rotor system were calculated by multi-dimensional harmonic balance combined with alternating frequency/time domain method (MHB-AFT). The effects of base harmonic rotations and mass unbalance on steady-state responses of rotor system were investigated. The results indicate that the time-varying parametric excitations of base motions have strong effects on amplitude-frequency response of transverse displacement of rotor system. The critical speeds and resonant amplitudes of responses change with the magnitude and frequency of several base harmonic rotations. The variation of the frequency of base harmonic motion has the most significant impact on the amplitude-frequency response of transverse displacement of rotor system. The increase of base harmonic frequency will lead to multiple local peaks in the response curves, especially in the case of base harmonic rolling motion. In addition, the combination of base harmonic rotation around pitching and yawing axes results in significantly different response characteristics. Therefore, the influence of base harmonic motions should be considered during the structural design and damping optimization of SFDs.
Robust Probabilistic Analysis of Deterioration-Induced Aeroelasticity in an Axial Turbine
Authors: Stania Lennart , Seume Joerg R. 
Published: November 2022

Abstract
The surface of a real-world turbine blade differs from the geometry of its model. Manufacturing tolerances, wear, and regeneration during the turbine’s lifetime impact the aerodynamic behaviour, stage efficiency, and parameters as previous probabilistic studies have shown. Aerodynamic changes lead to aeroelastic variances in downstream rows that can have a significant impact on high-cycle fatigue due to a possible increase of a blade’s vibration amplitude. The present study expands an existing tool chain to uni-directional aeroelastic full three dimensional simulations. The test object is the last stage of a low-pressure five-stage axial turbine; the geometric variances are applied to characteristic airfoil parameters of the vane by Latin hypercube sampling. A required sample size for an accurate sensitivity analysis is estimated a-priori and verified by computational simulations. The aerodynamic analysis identified the stagger angle, trailing-edge thickness, maximum thickness, and maximum camber as the most important parameters among the characteristic blade parameters. For large deviation in the stagger angle a non-monotonous influence on isentropic efficiency was found, which shows limitations of a sensitivity analysis based on the Spearman rank correlation coefficients. A variance-based sensitivity analysis was used for a more detailed analysis, which is capable to detect such non-monotonous relationships. In the aeroelastic simulations, the chord length, maximum camber, and the trailing-edge angle have the highest influence on aerodynamic forcing and damping on a downstream rotor blade of the changed stator blade. Furthermore, direct correlations between aerodynamic stage parameters and aerodynamic damping are shown, which allows reduced order modelling. The correlation between work coefficient and vibration amplitude was overlooked by the Spearman’s coefficient but identified by the variance-based approach. A maximum vibration amplitude is identified, indicating a potential of using probabilistic studies for adjusting the safety factors for high-cycle fatigue during the design process of blades.
Semi-Analytical Model for High-Speed Rotor Whirl Prediction: An Assumed Modes Formulation for an Axisymmetric Rotor With Non-Uniform Properties
Authors: Chatterjee Riju , Patel Ashutosh , Kumar Nirmal , Kumar Pramod 
Published: November 2022

Abstract
Most fully analytical treatments of rotor whirl are restricted to very simple rotor geometries, and have limited use while studying real-world rotors. Analysis of more complex rotors is routinely carried out in Finite Element software such as Ansys, but this is less effective at generating fundamental insights to inform the design process. This paper is motivated by the ongoing development of a Supercritical-CO2 turbine rotor, and illustrates a rotor model of intermediate complexity. Such a model, given the relative novelty of the turbine design task stemming from the very high rotational speeds required, will improve confidence in rotordynamic simulations and is expected to help with any future troubleshooting. The approach used is to consider the rotor’s rigidity and inertia to vary along its length as functions of spatial coordinate x, and obtain predictions of whirl speeds through a Lagrangian formulation with assumed modes. This method can accommodate axisymmetric rotors with variation in cross-section or material properties, or both. It is first demonstrated on a simple and analytically tractable rotor geometry. Then, it is applied to a simplified version of the turbine rotor, whose properties’ x-dependence is approximated by curves fit to a small number of datapoints obtained from simpler (non-rotordynamic) simulations.
Application of an Advanced Meta Model Selection Algorithm on the Sensitivity Analysis of a Cooled Turbine Blade
Authors: Diermeier Florian , Voigt Matthias , Mailach Ronald , Meyer Marcus 
Published: November 2022

Abstract
Probabilistic methods are growing more important in the aerospace industry due to the ability to describe the behaviour of complex systems in the presence of input parameter variance. Sensitivity analysis based on meta models can be utilized for this purpose. The reliability of the results is dependent on the surrogate model quality, which in turn depends on the available data. A priori the appropriate meta model type is not known.
An approach to automatically select the best fitting model for a given data set is presented in this paper. For comparison, polynomial regression with least squares fitting, moving least squares, radial basis functions, and support vector regression are used as candidate types. The selection of the best meta model type is based on two quality criteria utilizing a cross-validation (CV) scheme. The developed approach is demonstrated on the sensitivity analysis of a cooled turbine blade.
Efficient Surrogate Modeling for Turbine Blade Row Cyclic Symmetric Mode Shapes
Authors: Bhaduri Anindya , Li Jing , Ghosh Sayan , Wang Liping 
Published: November 2022

Abstract
In this study, we consider the Modal Cyclic Symmetric (MCS) analysis to generate the modal frequencies and mode shapes of a tip-shrouded turbine blade row. In total 87 input parameters are considered here that define the geometry of the turbine blades. The objective here is to build an efficient surrogate model which maps these input parameters to the mode shapes. The main challenge is the high dimensionality of a complex mode shape at a mesh resolution of industrial standard which is almost of the order of O(107). Thus, the idea here is to efficiently reduce the high dimensional output into a lower dimensional representation using the unsupervised deep learning architecture called the Convolutional Variational AutoEncoder (CVAE). The CVAE model helps in performing efficient surrogate model building using GE’s Bayesian Hybrid Model (BHM) in a lower dimensional output space as well as produce feasible mode shapes for new geometries after training.
Investigation of Self-Heating During Ultrasonic Fatigue Testing and Effect on Very High Cycle Fatigue Behavior of Titanium 6Al-4V
Authors: Celli Dino A. , Warner Justin , Scott-Emuakpor Onome , George Tommy 
Published: November 2022

Abstract
Very high cycle fatigue (VHCF) data and experiments, 107−109 cycles to failure, has traditionally been both a cumbersome and costly task to perform. However, characterizing VHCF behavior of material systems are critical for the design and sustainability of turbine engines as outlined in the turbine engine structural integrity program (ENSIP). With recent advancements, ultrasonic fatigue test systems have become increasingly available to generate VHCF fatigue data. A primary consideration for ultrasonic fatigue testing is the frequency of loading, the resulting thermal evolution, and its effect on fatigue life. To mitigate the heat generation within the specimen during experiments, cooling air is directed to the specimen and cyclic loading is performed by selecting an appropriate test frequency or defining a duty cycle rather than continuously subjected to fatigue. However, standardization of experimental test procedures remains ongoing and continues to be developed. In this study a Shimadzu USF-1000A ultrasonic fatigue test system is used to characterized VHCF behavior of Ti 6Al-4V to understand the effect of duty cycle and thermal evolution on fatigue life for ultrasonic fatigue testing. Titanium 6Al-4V test specimens are subjected to fully reversed axial fatigue at 20kHz exciting resonance in an axial mode to better characterize the experimental process. Three duty cycle configurations are investigated and its effect on fatigue life due to self-generated heat during the experiment. Heat generation is monitored in-situ via a single-point optical pyrometer and in-situ mechanical and thermal data is collected and compared to standardized servo-hydraulic fatigue test data performed in this study as well as from data found in the literature.
Experimental Investigation of Three-Dimensional Shroud Contact Forces in Forced-Vibration Testing of a Shrouded Blade
Authors: Ahmed Rizwan , Firrone Christian Maria , Zucca Stefano 
Published: November 2022

Abstract
Low Pressure Turbine (LPT) blades encounter highly stressed forced vibrations driven by centrifugal force and steady/unsteady aerodynamic loads. To prevent the blades from failure due to high cycle fatigue (HCF), the amplitude of these vibrations must be estimated and reduced. Friction damping devices like under-platform dampers, shrouds and snubbers are usually implemented to lessen these blade vibration amplitudes. For adjacent shrouded blades coupled to each other at the blade tips, the blade vibration levels are strongly affected by the three-dimensional periodic contact forces at shrouds resulting in energy dissipation due to friction. Therefore, to experimentally validate the numerical contact models that predict nonlinear forced response of shrouded blades, it is equally important to measure the contact forces acting at the shrouds.
This study outlines the development and commissioning of an experimental test rig that allows the measurement of three-dimensional shroud contact forces and the forced response of the shrouded blade simultaneously. Firstly, the design requirements of the experimental setup that were considered while deciding the test rig components, are highlighted. The test rig comprises of a pair of tri-directional contact force transducers in contact with the two shroud ends of a dummy blade and includes a blade twisting mechanism for the application of the normal preload. The employed tri-directional contact force transducers consist of three uniaxial strain gauge-based force sensors, arranged in a tripod configuration, and attached to a reference block that accommodates the shroud. The calibration and the decoupling procedure of the tri-directional contact force measurement system is then briefly described. This is followed by the details of the experimental process to acquire the forced response and three-dimensional shroud contact forces simultaneously for a specified frequency range determined by a prior experimental modal analysis of the blade and test rig. Subsequently, the effects of the variation in shroud normal preload and excitation force on measured response and shroud contact forces are also discussed. Finally, the results demonstrate how the proposed experimental test rig provides a thorough understanding of the dynamic response of the shrouded blade and shroud contact forces which will lead to a more reliable experimental validation of simulation tools and its effect on system dynamics.
Late Messinian submarine channel systems in the Levant Basin: Challenging the desiccation scenario
Authors: Moneron Jimmy , Gvirtzman Zohar 
Published: November 2022

Abstract
The question of whether the Mediterranean Sea desiccated during the Messinian salinity crisis (MSC) has been strongly debated for decades. In the Levant Basin, this debate was recently reignited in relation to the latest stage of the crisis after cessation of salt deposition. The desiccation supporters argue that salt truncation—and its subsequent burial by a latest Messinian, clastic-rich evaporitic unit—occurred subaerially on a desiccated seafloor. However, we show that this latest Messinian unit contains a dense net of channels with meanders, levees, and overspill deposits and is very similar to the turbidite channels observed on the modern seafloor. The aggradation characteristics of these buried channels (levee height, channel depth, and channel-floodplain coupling) indicate a marine rather than fluvial origin. Our conclusion adds to the findings of a previous study that salt truncation occurred in deep waters by dissolution. In a wider perspective, we suggest that the flush of clastics into the basin during the last stage of the MSC indicates a combination of wet climate and sea-level rise that started before the Zanclean (earliest Pliocene).
Shifting paradigm from biomedical to decolonised methods in Inuit public health research in Canada: a scoping review
Authors: Belaid Loubna , Budgell Richard , Sauvé Caroline , Andersson Neil 
Published: November 2022

BackgroundThe National Inuit Strategy on Research focuses on advancing Inuit governance in research, increasing ownership over data and building capacity. Responding to this call for Inuit self-determination in research, academic researchers should consider cultural safety in research and ways to promote Inuit-led methods.MethodsThis scoping review collated academic literature on public health research in Inuit communities in Canada between 2010 and 2022. A critical assessment of methods used in public health research in Inuit communities examined cultural safety and the use of Inuit-attuned methods. Descriptive and analytical data were summarised in tables and figures. Knowledge user engagement in the research process was analysed with thematic analysis.Results356 articles met the inclusion criteria. Much of the published research was in nutrition and mental health, and few initiatives reported translation into promotion programmes. Almost all published research was disease or deficit focused and based on a biomedical paradigm, especially in toxicology, maternal health and chronic diseases. Recent years saw an increased number of participatory studies using a decolonial lens and focusing on resilience. While some qualitative research referred to Inuit methodologies and engaged communities in the research process, most quantitative research was not culturally safe. Overall, community engagement remained in early stages of co-designing research protocols and interventions. Discussion on governance and data ownership was limited. Recent years saw emerging discussions on these issues. Knowledge user capacity-building was limited to brief training on conventional data collection methods.ConclusionsThe last decade of published public health research has not responded to the National Inuit Strategy on Research. Participatory research is gaining ground, but has not reached its full potential. A shift from biomedical to decolonised methods is slowly taking place, and public health researchers who have not yet embraced this paradigm shift should do so.
Prevalence of Alzheimer′s disease in rural and urban areas in Cuba and factors influencing on its occurrence: epidemiological cross-sectional protocol
Authors: López Ricardo Yudisleidy , Reyes Zamora Mary Carmen , Perodin Hernández Janet , Rodríguez Martínez Claudio 
Published: November 2022

IntroductionAccording to the World Alzheimer’s Report 2019, around 50 million people suffer from dementia, worldwide. Observational analysis revealed the existence of particular factors associated with the onset and progression of Alzheimer’s disease (AD). There are no international homogeneous principles for the early detection and evaluation of memory impairment and possible AD. This work aimed at (1) determining the prevalence of possible AD in the elderly residing in urban and rural regions in Cuba and (2) identifying the main factors that could significantly influence on its occurrence.Methods and analysisThe study includes four neuropsychological tests (Clock Drawing Test, Mini-Mental Status Examination, Short Portable Mental Status Questionnaire, Cognitive and Non-Cognitive Alzheimer′s Disease Assessment Scale) and two scales (Clinical Dementia Rating and Global Deterioration Scale). Moreover, the protocol includes a survey with demographic and socioeconomic information, educational level, occupation, health, neuropsychological status of subjects, familial pathological history, comorbidities and lifestyles. The study will comprise a total of 1092 subjects aged ≥60, of both genders, and from every ethnic group settled in rural and urban areas. Primary outcomes: prevalence of possible AD. Secondary outcomes: correlation among risk and protective factors and AD, and comparison of the performance of neuropsychological tests and scales.Ethics and disseminationThis research met the ethical codes of the Declaration of Helsinki. The Scientific Research Council of the Promoting Research Institute and the Ethics Committee of the Health Authorities approved the protocol. The proper written informed consent is also incorporated. The results of the survey will be published in scientific papers and shared with the Health Authorities of each municipality.
Mediating role of emotional labour strategy in the association between patient/visitor incivility and nurses’ fatigue: a cross-sectional study
Authors: Bai Ru , Zhang Di , Zhang Qiuling , Sun Yu , Luo Nansheng , Li Mengyao , Wu Hui , Liu Li 
Published: November 2022

ObjectiveFatigue is a common problem among nurses, and patient/visitor incivility is thought to lead to nurses’ fatigue. However, the mechanism by which patient/visitor incivility leads to nurses’ fatigue has not been well studied. The aim of this study is to examine whether the association between patient/visitor incivility and fatigue among Chinese nurses is mediated by emotional labour strategy.DesignA cross-sectional study.MethodsIn November 2019, a stratified cluster sample of 1207 nurses from two hospitals in China was used to collect data on fatigue, patient/visitor incivility and emotional labour strategy through online questionnaires. Emotional labour strategy has three dimensions: surface acting (SA), deep acting and natural acting. Complete responses were provided by 1036 (85.8%) participants. Student’s t-test, one-way analysis of variance, Pearson correlation analysis and the PROCESS procedure (A modeling macro installed in SPSS to analyse mediation.) were adopted to analyse the data.ResultsPatient/visitor incivility and SA were positively related to fatigue (p<0.01), while natural acting was negatively related to fatigue (p<0.01). SA played as a mediator in the association between patient/visitor incivility and nurses’ fatigue (95% CI 0.047 to 0.113, p<0.05).ConclusionPatient/visitor incivility could contribute to Chinese nurses' fatigue. When nurses were exposed to patient/visitor incivility, they were more likely to use the SA emotional labour strategy, which would lead to fatigue. Nursing administrators should be aware of the seriousness of nurses’ fatigue.