bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Dynamics of Turbine Generator Shaft Trains: Evaluation of Bifurcation Sets Applying Numerical Continuation
Authors: Gavalas Ioannis , Chasalevris Athanasios 
Published: November 2022

Abstract
The nonlinear dynamics of turbine generator shaft trains for power generation are investigated in this paper. Realistic models of rotors, pedestals, and nonlinear bearings of partial arc and lemon bore configuration are implemented to compose a nonlinear set of differential equations for autonomous (balanced) and non-autonomous (unbalanced - per ISO) cases. The solution branches of the dynamic system are evaluated with the pseudo arc length continuation programmed by the authors, and the respective limit cycles are evaluated by an orthogonal collocation method, and investigated on their stability properties and quality of motion for the respective key design parameters for the rotor dynamic design of such systems, namely: bearing profile and respective pad length, preload and offset, pedestal stiffness and elevation (misalignment), and rotor slenderness. Model order reduction is applied to the finite element rotor model and the reduced system is validated in terms of unbalance response and stability characteristics.
The main conclusion of the current investigation is that the system has the potential to develop instabilities in rotating speeds lower than the threshold speed of instability (evaluated by the linear approach) for specific unbalance magnitude and design properties. Unbalance response (with stable and unstable branches) is evaluated in severely reduced time compared to this applying time integration methods, enabling nonlinear rotor dynamic design of such systems as a standard procedure, and revealing the complete potential of motions (not only local).
Mistuning Effects on Aero-Elastic Stability of Civil Transonic Fan Blades
Authors: Lian Bo , Zhu Xiaocheng , Du Zhaohui 
Published: November 2022

Abstract
Flutter seriously affects the safety and reliability of aeroengine. The blade mistuning is inevitable due to machining error and service wear, which has a significant influence on flutter stability. In this paper, the eigenvalue method is used to calculate the aerodynamic damping of transonic fan blades of civil aviation engine at different nodal diameters (NDs) and structural modes. The results show that under the design condition, the first three structural modes of the blade are aero-elastic stable for each ND, and the aerodynamic damping gets the minimum at ND1 for the first bending mode. As the back pressure deviates from design condition towards stall, the aerodynamic damping obviously decrease and even negative aerodynamic damping occurs at normalized mass flow rate of 0.930. Six kinds of mistuning patterns are considered based on the eigenvalue method, divided into two categories: structural mistuning and aerodynamic mistuning, where structural mistuning includes alternate mistuning, sinusoidal mistuning and random mistuning. The alternate mistuning has better improvement on flutter suppression than the sinusoidal mistuning with the same frequency offset, though further increasing the amount of mistuning cannot provide extra aero-damping when the frequency offset reaches a critical value of 7%. For the aerodynamic mistuning, the improvement of aero-damping is limited in comparison with the structural mistuning, especially for the random mistuning through Monte Carlo simulations. Based on the analysis of eigenvectors, the single blade aerodynamic mistuning breaks the periodic pattern in travelling wave mode, which tends to make the aero-elastic systems stable. While the symmetry group mistuning maintains the periodicity and destabilizes the aero-elastic system.
Evaluating the Aerodynamic Damping at Shock Wave Boundary Layer Interacting Flow Conditions With Harmonic Balance
Authors: Heners Jan Philipp , Carraro Thomas , Frey Christian , Grüber Björn 
Published: November 2022

Abstract
The aerodynamic damping of a stator vane located in a rear stage of a high pressure compressor is evaluated at transonic flow conditions by numerical means. The results of a solution method based on temporal linearization around a steady RANS state are compared to results generated by relying on a state-of-the-art harmonic balance solver. It is found that the time-linearized method is not capable to reproduce the damping behavior in a sufficient manner for the majority of assessed nodal diameters. The limitations of the time-linearized method consisting in expansion around an imperfect steady RANS state, neglecting non-linear contributions and considering turbulence to be frozen at its steady state are evaluated and quantified.
Furthermore, the presence of unsteady content induced by shock wave boundary layer interaction can be identified by performing a full-annulus URANS simulation based on time-integration. For a limited range of nodal diameters, this shock boundary layer interaction locks in to the assessed flutter motion and affects the damping behavior substantially. It is demonstrated that the mechanism of the shock wave boundary layer interaction can be reproduced with harmonic balance in accordance to the time-integration method. Coupling the eigenmode of interest and the identified shock boundary layer interaction via the harmonic balance method allows to predict the aerodynamic damping for the affected nodal diameters.
A Comparative Study of Crystal Visco-Plastic Modeling of Directionally Solidified Nickel-Base Superalloys
Authors: Wijeyeratne Navindra , Irmak Firat , Gordon Ali P. 
Published: November 2022

Abstract
Nickel-base superalloys (NBSAs) are a group of materials that are used in high-temperature applications such as gas turbine components. These materials are renowned for their superior strength and fatigue properties at high temperatures. This work primarily focuses on Directionally solidified (DS) NBSAs. Directionally solidified materials are comprised of columnar grains which are parallel to the &lt;001&gt; direction. The alignment of the grain boundaries in the direction of the stress axis enhances the strength properties of these materials at elevated temperatures. To improve the design process, utilizing a framework consisting of numerical simulations coupled with experimental analysis is essential. Due to the grain structure the properties of DS-NBSAs exhibit temperature dependence and anisotropic behavior. Crystal visco-plastic (CVP) models can simulate the effects of temperature and orientation dependence under a variety of loading conditions such as tensile, low cycle fatigue (LCF), and thermomechanical fatigue (TMF). The formulation of the CVP model comprises a flow rule combined with internal state variables to define the shearing rate for each slip system. The internal state variable captures the kinematic and isotropic hardening effects. The crystallographic slip is described by incorporating the necessary octahedral, cubic, and cross slip systems. The CVP model is initially developed for a single crystal (SX) material and then adapted to DS material to represent the columnar grain structure. Modeling DS materials is significantly more complex than single crystal (SX) materials since the grains are entangled at the boundary. In past studies, the development of CVP models for DS materials was mainly accomplished by applying the SX CVP model to the DS materials implicitly or explicitly. The Implicit approach for the DS CVP model can be developed by extending the SX CVP model where each individual grain is modeled as a single crystal. The explicit method maps the columnar grains and orientation onto a plane finite element model. Both of these modeling approaches require the application of the SX CVP model to multiple grains which consequently results in them being highly computationally expensive. A crystal visco-plastic model for DS materials that circumvents the modeling of individual grains was presented by the authors at turbo expo 2021. The primary objective of this work is to utilize the three types of DS-CVP models for the same materials to investigate their performance. Comparisons will be performed at various temperatures and orientations. The results of the models are compared to analyze their pros and cons and applicability etc. Comparisons of these three types of modeling approaches applied to the same material have not been presented before in the literature and will provide an excellent insight into the usability of these constitutive models.
Impact of stream power gradients on storage of sediment and carbon on channel margins and floodplains
Authors: Gartner John D. , Renshaw Carl E. , Landis Joshua , Magilligan Francis J. 
Published: November 2022

AbstractSpatial complexity impacts the resilience of river ecosystems by mediating processes that control the sources and sinks of sediment and organic material. Using four independent geochemical tracers and three morphometric indices, we show that downstream spatial gradients in stream power (Ω) predict storage of material in the channels and margins and/or floodplains. A field test in a 48 km2 watershed demonstrates that reaches with downstream decreases in Ω coincide with wider floodplains and elevated inventories of 137Cs, 210Pbex (ex—excess), and organic matter in locations of the ~3 to 20 yr floodplain. In contrast, reaches with downstream increases in Ω coincide with narrower floodplains and decreased inventories of 137Cs, 210Pbex, and organic matter. The occurrence of in-channel bedrock exposures and the activity of short-lived 7Be in within-channel sediments also correlate with downstream Ω gradients, demonstrating a link, over both short and long time scales, between withinchannel processes and floodplain-forming processes. The combined geochemical and physical characteristics demonstrate the importance of downstream gradients in sediment transport, characterized by downstream changes in stream power rather than at-a-point stream power, in determining spatial complexity in carbon and sediment storage at intermediate scales (102 to 103 m) in river systems.
Major-element geochemistry of pelites
Authors: Forshaw Jacob B. , Pattison David R.M. 
Published: November 2022

AbstractPelites (shales and mudstones) are arguably the most important rock type for interpreting metamorphism. Their significance derives from their widespread occurrence and the range of mineral assemblages they develop at different conditions of pressure and temperature. We compiled a global database of 5729 major-element whole-rock analyses of pelites from different metamorphic grades (shales to granulite-facies paragneisses) to (1) determine an average composition, (2) examine the range and variability in their composition, and (3) assess if there is evidence for grade-related geochemical changes. Median values are given instead of average values to eliminate the effect of extremes. The median worldwide pelite is as follows (anhydrous, values in wt%): SiO2 = 64.13, TiO2 = 0.91, Al2O3 = 19.63, FeOtotal = 6.85, MnO = 0.08, MgO = 2.41, CaO = 0.65, Na2O = 1.38, and K2O = 3.95. The median XMg = MgO/(MgO + FeOtotal) in moles is 0.39. The median XFe3+ = 2 × Fe2O3/(2 × Fe2O3 + FeO) in moles was measured in 1964 samples and is 0.23. On an Al2O3-FeO-MgO (AFM) diagram, the median worldwide pelite plots within a strong clustering of analyses between = projected molar MgO/(MgO + FeOtotal) = 0.30–0.55 (median = 0.42) and AMs = molar [Al2O3 – (3 × K2O)]/[Al2O3 – (3 × K2O) + FeOtotal + MgO] = 0.0–0.4 (median = 0.19). Pelites show a continuous decrease in volatile content with increasing meta-morphic grade and a decrease in XFe3+ from the diagenetic to biotite zone. Lower median SiO2 values and higher median Al2O3 and AMs values in the porphyroblast and subsolidus sillimanite or K-feldspar zones, as well as higher median MnO values in the garnet zone, may reflect sampling bias or metasomatism.
Risk factors for workplace bullying, severe psychological distress and suicidal ideation during the COVID-19 pandemic among the general working population in Japan: a large-scale cross-sectional study
Authors: Tsuno Kanami , Tabuchi Takahiro 
Published: November 2022

ObjectivesTo investigate the risk factors for workplace bullying and mental health outcomes among workers during the COVID-19 pandemic.DesignA cross-sectional study.SettingA nationwide online survey was conducted from August to September 2020 in Japan.Participants16 384 workers (men: n=9565; women: n=6789).Main outcome variablesWorkplace bullying was measured by one item from the Brief Job Stress Questionnaire; severe psychological distress according to the Kessler Psychological Distress Scale (≥13) and suicidal ideation by one item. Prevalence ratios were calculated by modified Poisson regression analyses adjusting for potential confounders such as gender, age, occupational characteristics and a prior history of depression.ResultsOverall, 15% of workers experienced workplace bullying, 9% had severe psychological distress and 12% had suicidal ideation during the second and third wave of the COVID-19 pandemic in Japan. The results of this study showed men, executives, managers and permanent employees had a higher risk of bullying than women or part-time workers. Increased physical and psychological demands were common risk factors for bullying, severe psychological distress and suicidal ideation. Starting to work from home was a significant predictor for adverse mental health outcomes but a preventive factor against workplace bullying.ConclusionsThe results of this study showed different high-risk groups for bullying or mental health during the pandemic. Any intervention to decrease workplace bullying or mental health problems should focus not only on previously reported vulnerable workers but also workers who have experienced a change in work style or job demands.
Longitudinal Aging Study Amsterdam COVID-19 exposure index: a cross-sectional analysis of the impact of the pandemic on daily functioning of older adults
Authors: Hoogendijk Emiel O , Schuster Noah A , van Tilburg Theo G , Schaap Laura A , Suanet Bianca , De Breij Sascha , Kok Almar AL , Van Schoor Natasja M , Timmermans Erik J , de Jongh Renate T , Visser Marjolein , Huisman Martijn 
Published: November 2022

ObjectivesThe aim of this study was to develop an index to measure older adults’ exposure to the COVID-19 pandemic and to study its association with various domains of functioning.DesignCross-sectional study.SettingThe Longitudinal Aging Study Amsterdam (LASA), a cohort study in the Netherlands.ParticipantsCommunity-dwelling older adults aged 62–102 years (n=1089) who participated in the LASA COVID-19 study (June–September 2020), just after the first wave of the pandemic.Primary outcome measuresA 35-item COVID-19 exposure index with a score ranging between 0 and 1 was developed, including items that assess the extent to which the COVID-19 situation affected daily lives of older adults. Descriptive characteristics of the index were studied, stratified by several sociodemographic factors. Logistic regression analyses were performed to study associations between the exposure index and several indicators of functioning (functional limitations, anxiety, depression and loneliness).ResultsThe mean COVID-19 exposure index score was 0.20 (SD 0.10). Scores were relatively high among women and in the southern region of the Netherlands. In models adjusted for sociodemographic factors and prepandemic functioning (2018–2019), those with scores in the highest tertile of the exposure index were more likely to report functional limitations (OR: 2.24; 95% CI: 1.48 to 3.38), anxiety symptoms (OR: 3.14; 95% CI: 1.82 to 5.44), depressive symptoms (OR: 2.49; 95% CI: 1.55 to 4.00) and loneliness (OR: 2.97; 95% CI: 2.08 to 4.26) than those in the lowest tertile.ConclusionsAmong older adults in the Netherlands, higher exposure to the COVID-19 pandemic was associated with worse functioning in the physical, mental and social domain. The newly developed exposure index may be used to identify persons for whom targeted interventions are needed to maintain or improve functioning during the pandemic or postpandemic.
Identification of patient-related, healthcare-related and knowledge-related factors associated with inadequate blood pressure control in outpatients: a cross-sectional study in Serbia
Authors: Horvat Olga , Halgato Tinde , Stojšić-Milosavljević Anastazija , Paut Kusturica Milica , Kovačević Zorana , Bukumiric Dragica , Tomas Ana 
Published: November 2022

ObjectivesTo determine rate of blood pressure (BP) control and to analyse patient-related, medication-related and healthcare system-related factors associated with poor BP control in outpatients with hypertension (HT).DesignCross-sectional study.SettingTwo study sites with different levels of healthcare (primary healthcare (PHC) and secondary level of healthcare (SHC)) in Vojvodina, Northern Serbia.ParticipantsA total of 581 patients (response rate 96.8%) visiting their primary care physician between July 2019 and June 2020 filled out a pretested semistructured questionnaire and had a BP reading during their regular appointments.Primary and secondary outcome measuresData on demographics, medication, BP control (target systolic BP≤140 mm Hg and∕ or diastolic BP≤90 mm Hg) and knowledge on HT was collected. Based on the median of knowledge score, patients were classified as having poor, average and adequate knowledge.ResultsMajority of the respondents (74.9%) had poorly controlled BP and had HT longer than 10 years. Larger number of patients at PHC site was managed with monotherapy while at the SHC majority received three or more antihypertensive drugs. Respondents from SHC showed a significantly lower knowledge score (9, 2–15) compared with the respondents from PHC (11, 4–15, p=0.001). The share of respondents with adequate knowledge on HT was significantly higher in the group with good BP control (26% and 9.2%, respectively). In a multivariate regression analysis, factors associated with poor BP control were knowledge (B=−1.091; p<0001), number of drugs (B=0536; p<0001) and complications (B=0898; p=0004).ConclusionsPoor BP control is common in outpatients in Serbia, irrespective of the availability of different levels of healthcare. Patients with poor knowledge on HT, with complications of HT and those with multiple antihypertensive drugs, were at particular risk of poor BP control. Our study could serve as a basis for targeted interventions to improve HT management.
Clinical outcomes of automated versus continuous ambulatory peritoneal dialysis for end-stage kidney disease: protocol of a systematic review and meta-analysis
Authors: Shi Xinmiao , Du Hui , Zhang Zhouhang , Zhou Yun 
Published: November 2022

IntroductionAn increasing number of studies comparing automated peritoneal dialysis (APD) with continuous ambulatory peritoneal dialysis (CAPD) in clinical outcomes have been published since the publication of a systematic review and meta-analysis including three randomised controlled trials in 2007. We will conduct a systematic review and meta-analysis to explore more clinical outcomes of APD versus CAPD for end-stage kidney disease.Methods and analysisThe protocol is conducted following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines. Three databases—PubMed, EMBASE and the Cochrane Library—will be searched comprehensively from inception to 16 June 2022, without language restriction. Studies reporting clinical outcomes comparing APD with CAPD will be included. Two independent reviewers will screen the titles and abstracts and then obtain and assess full texts of potential relevant articles for eligibility following the inclusion and exclusion criteria. The methodological quality of included observational studies will be assessed by using the Newcastle–Ottawa Scale. The risk of bias of included randomised controlled studies will be assessed by using the Cochrane Risk of Bias tool. Relative risk for dichotomous outcomes and standard mean difference for continuous outcomes with corresponding 95%CIswill be pooled for summary effects. Cochrane Q test andI2values will be used to assess heterogeneity between studies. To assess and explore the source of heterogeneity, subgroup analyses and sensitivity analyses will be conducted, and meta-regression, funnel plot and Egger’s test will be performed if there are no less than 10 studies. Analyses will be performed using STATA software, V.13.0 (STATA Corporation, College Station, Texas, USA).Ethics and disseminationEthics approval is not applicable as no personal information is collected from patients. The results will be published in a peer-reviewed journal or disseminated in relevant academic conferences.PROSPERO registration numberCRD42022311401.
Prevalence of homocysteinemia and effect of vitamin supplementation in retinal vein occlusion
Authors: Levi Maxwell , Harb Amro A , Trippiedi Andrew , Rodriguez Sophia , Vianna Nicholas , Higgins Lisa M , Kallina Lauren , Angioletti Lee , Gutman Justin , Higgins Patrick M 
Published: November 2022

ObjectiveThe objective of this study was to determine the prevalence of homocysteinemia in patients with retinal vein occlusion (RVO). We investigated the association of B complex vitamin (BCV) and multivitamin (MVI) supplementation on homocysteine levels in RVO patients.Methods and analysisThis cross-sectional study occurred at the Retina Center of New Jersey. We investigated 312 patients diagnosed with RVO between 2011 and 2019. Homocysteine levels were measured on diagnosis of RVO and 4–8 weeks after, following recommended daily supplementation with BCV, MVI or combination MVI+BCV.ResultsThe median patient age was 71.00, IQR (61.00, 78.25), with 164 (52.6%) being women. Prevalence of homocysteinemia (>13 µmol/L) was 150 of 312 (48.1%), with a median baseline homocysteine level of 12.80 (10.17, 15.90) µmol/L. The follow-up cohort, 105 patients, demonstrated significant reduction in median homocysteine levels from 14.50 (12.30, 17.90) to 10.70 (9.30, 13.50) µmol/L following vitamin supplementation. Multivariate analysis found having baseline homocysteinemia was significantly associated with at least 25% reduction in homocysteine following vitamin supplementation.ConclusionsIn this study, 48.1% of patients with RVO had elevated homocysteine (>13 µmol/L). Supplementation with BCV or MVI+BCV was associated with a significant reduction in homocysteine from 14.50 (12.30, 17.90) to 10.70 (9.30, 13.50) µmol/L.