bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Optimization Methodology for Turbines Driven by Pulsed Detonation Combustors
Authors: Asli Majid , Stathopoulos Panagiotis 
Published: September 2022

Abstract
A step-change in efficiency of gas turbine technology and, subsequently, an emissions reduction from this technology requires conceptual changes. Substituting conventional combustion chambers with pressure gain combustion in the form of pulsed detonation combustion (PDC) is one of the promising methods that can reduce gas turbine emissions significantly. Nevertheless, the component matching for the respective systems and specifically that of turbine expanders working with the exhaust flow of PDC tubes is still not solved. The unsteady nature of PDC exhaust flow makes 3D-CFD simulations too expensive to be applied in optimization loops in early design stages. To address this question, the present paper introduces a new cost-effective but reliable methodology for turbine analysis and optimization, based on the unsteady exhaust flow of pulsed detonation combustors. The methodology unitizes a robust unsteady one-dimensional solver, a meanline performance analysis, and an adaptive surrogate optimization algorithm. A two-stage axial turbine is optimized considering all unsteady flow features of a hydrogen-air PDC configuration with five PDC tubes. A three-dimensional URANS simulation is performed for the optimized geometry and the baseline to evaluate the methodology. The results showed that the optimized turbine produces 16% lower entropy than the original one. Additionally, the turbine output power is increased by 14% by the optimized design. Based on the results, it is concluded that the approach is fast and reliable enough to be applied in optimizing any turbine working with unsteady flows, more specifically in PDC applications.
Investigating the Mixture Quality in Multi-Injector Burner Systems—Part I: Experimental Setup
Authors: Macias Fabian Marquez , Hirsch Christoph , Sattelmayer Thomas , Huth Michael , Meisl Jürgen 
Published: September 2022

Abstract
A new approach to calculate the mixture statistics in multi-injector burner (MIB) systems from a single injector database is presented in the paper. In such systems, the mixture quality is highly sensitive to the flowrate and the skewness of the inflow velocity profile. To determine the mixture fraction statistics from these two parameters for a particular injector in a multi-injector configuration, output-based proper orthogonal decomposition (O-POD) is suggested using results from Reynolds-averaged Navier Stokes (RANS)–computational fluid dynamics (CFD) as the observable. The O-POD mixing database is determined experimentally from two setups: First, the mixture quality in a single injector at ideal inflow conditions is studied. Then the same injector type is investigated in a generic MIB system. To characterize the mixture quality, the mixing probability mass function (PMF) at the injector exit is measured by means of laser-induced fluorescence (LIF) and high speed imaging. The data obtained for both the single injector under ideal inflow and the MIB are presented. These studies of the mixture behavior reveal that an asymmetric inflow velocity profile leads to a significant increase of unmixedness, which is seen as a negative skewness of the mixing PMFs. This effect becomes stronger at higher momentum flux density ratios due to the higher penetration depth of the fuel jets. The application of the O-POD to the database shows that the PMF can be accurately modeled with only three modes.
Stability Analysis of an Industrial Blade Accounting for a Blade-Tip/Casing Nonlinear Interface
Authors: Colaïtis Yann , Batailly Alain 
Published: September 2022

Abstract
This paper investigates the local stability analysis of periodic solutions corresponding to the nonlinear vibration response of an industrial compressor blade, NASA rotor 37, on which are applied different types of nonlinearities. These solutions are obtained using a harmonic balance method-based approach presented in a previous paper. It accounts for unilateral contact and dry friction of the rotating blade against a rigid casing through a regularized penalty law. A Lanczos filtering technique is also employed to mitigate spurious oscillations related to the Gibbs phenomenon thus enhancing the robustness of the solver. In addition, a component mode synthesis technique is used to reduce the dimension of the numerical model. Stability assessment of the computed solutions relies on Floquet theory. It is performed through the computation of the monodromy matrix as well as Hill's method. Both methodologies are applied and thoroughly compared as the severity of the nonlinearity is gradually increased from a cubic spring to three-dimensional contact conditions on a deformed casing. While the presented results underline the applicability of both stability assessment methodologies for all types of nonlinearities, they also put forward the much higher computational effort required when computing the monodromy matrix. Indeed, it is shown that Hill's method yields converged results for significantly lower values of both the number of retained harmonics and the considered number of time steps thus making it a far more efficient method when dealing with industrial models. It is also underlined that the presented results are in excellent agreement with reference solution points obtained with time domain solution methods. Specific implementation tweaks that were found to be of critical importance in order to efficiently assess the stability of computed solutions are also detailed in order to provide a comprehensive view of the challenges inherent to such numerical developments.
Life Cycle Assessment for Rough Machining of Inconel 718 Comparing Ceramic to Cemented Carbide End Mills
Authors: Fricke Kilian , Zimmermann Richard , Ganser Philipp , Gierlings Sascha , Bergs Thomas 
Published: September 2022

Abstract
Nickel-based alloys such as Inconel 718 belong to the group of heat-resistant super alloys. Combined with good mechanical properties over a wide range of temperatures, nickel alloys are used extensively in the aero engine sections exposed to elevated temperatures. Besides turbine blades and disks, integrally designed compressor rotors (Blisks) in the high-pressure compressor are increasingly made of Ni alloys. This is the result of an efficiency-driven increase in temperature levels in the rear compressor stages. The machining of these hard-to-machine materials is characterized by low productivity and high tool wear. Compared to the machining with conventional cemented carbide end mills, innovative SiAlON ceramics offer a significant potential to increase the performance of these machining processes while saving cooling-lubricants. Besides an increase in productivity, the evaluation of the overall environmental impact of specific manufacturing processes is gaining importance in the context of more sustainable product life cycles. This paper focuses on the comparison of different milling strategies in the production of high-pressure compressor rotors made from Inconel 718 in a cradle-to-gate assessment based on DIN EN ISO 14040/44. Thus, the ecological impact of both the state-of-the-art and the novel SiAlON roughing strategy are evaluated considering the consumption of energy, water and compressed air as well as the tool wear. The life cycle impact analysis (LCIA) will be performed as a midpoint analysis taking multiple indicators into account such as the global warming potential (GWP).
An Experimental Investigation on the Dynamic Response Variability of a Turbine Blade With Midspan Dampers
Authors: Ferhatoglu Erhan , Botto Daniele , Zucca Stefano 
Published: September 2022

Abstract
This paper addresses two main subjects. First, a novel test setup is described to experimentally study the nonlinear dynamic behavior of a turbine blade coupled with two midspan dampers (MSDs). To this end, a representative turbine blade and midspan friction dampers are originally designed, and they are assembled to a special test rig which has been previously developed at Politecnico di Torino. Second, the variability of the dynamic response is intensively investigated with a purposely defined loading/unloading strategy. To better understand the inherent kinematics of the blade–damper interaction, contact forces are measured through the novel design of the experimental campaign. It is shown that multiple responses, which are obtained in different tests while keeping all user-controlled inputs nominally same, are due to nonunique contact forces that provide different static force equilibria on the damper. This outcome is further supported by the qualitative illustration of hysteresis cycles. This study contributes to the understanding of the response repeatability linked to the nonuniqueness of friction forces.
Gas Turbine Combined Cycle Range Enhancer—Part 2: Performance Demonstration
Authors: Reboli Tommaso , Ferrando Marco , Gini Lorenzo , Mantelli Luca , Sorce Alessandro , Traverso Alberto 
Published: September 2022

Abstract
In the current energy scenario, gas turbine combined cycles (GTCCs) are considered key drivers for the transition towards fossil-free energy production. However, to meet this goal, they must be able to cope with rapid changes in power request and extend their operating range beyond the limits imposed by the environmental conditions in which they operate. The European H2020 project PUMP-HEAT (Pump-Heat Project, 2021, D4. 6 – “Validation Results in Energy -Hub of MPC With Cold Thermal Storage,”) aims at achieving this goal thanks to the integration of the GTCC with a heat pump (HP) and a thermal energy storage (TES). To study this setup, a dedicated cyber-physical facility was built at the University of Genova laboratories, Italy. The plant includes physical hardware, such as a 100kWel microgas turbine, (mGT), a 10 kWel HP and a 180 kWh change phase material-based TES. These real devices are up-scaled thanks to performance maps and real-time dynamic models to emulate a full-scale heavy-duty 400 MW GTCC with a cyber-physical approach. The control system determines the optimal configuration of the whole plant and the operative point of the real devices to minimize the mismatch with a real electric power demand curve. Different operative configurations are tested: one for reducing the power production of the plant below the minimum environmental load (MEL) and two for augmenting the plant maximum power under certain ambient conditions. From the analysis of these tests, it is possible to verify the effectiveness of the proposed concept and characterize the transient behavior of the real components.
First post-Newtonian N-body problem in Einstein–Cartan theory with the Weyssenhoff fluid: equations of motion
Authors: Battista Emmanuele , Falco Vittorio De 
Published: September 2022

AbstractWe derive the equations of motion for an N-body system in the Einstein–Cartan gravity theory at the first post-Newtonian order by exploiting the Weyssenhoff fluid as the spin model. Our approach consists in performing the point-particle limit of the continuous description of the gravitational source. The final equations provide a hint for the validity of the effacing principle at 1PN level in Einstein–Cartan model. The analogies with the general relativistic dynamics involving the macroscopic angular momentum are also discussed.
Scaling of urban amenities: generative statistics and implications for urban planning
Authors: Kaufmann Talia , Radaelli Laura , Bettencourt Luis M. A. , Shmueli Erez 
Published: September 2022

AbstractCities have been extensively studied as complex adaptive systems over the last 50 years. Recently, several empirical studies and emerging theory provided support for the fact that many different urban indicators follow general consistent statistical patterns across countries, cultures and times. In particular, total personal income, measures of innovation, crime rates, characteristics of the built environment and other indicators have been shown to exhibit non-linear power-law scaling with the population size of functional cities. Here, we show how to apply this type of analysis inside cities to establish universal patterns in the quantity and distribution of urban amenities such as restaurants, parks, and universities. Using a unique data set containing millions of amenities in the 50 largest US metropolitan areas, we establish general non-linear scaling patterns between each city’s population and many different amenities types, the small-area statistics of their spatial abundance, and the characteristics of their mean distance to each other. We use these size-specific statistical findings to produce generative models for the expected amenity abundances of any US city. We then compute the deviations observed in given cities from this statistical many-amenity model to build a characteristic signature for each urban area. Finally, we show how urban planning can be guided by these systemic quantitative expectations in the context of new city design or the identification of local deficits in service provision in existing cities.
The Short-Term Effect of COVID-19 Pandemic on China’s Crude Oil Futures Market: A Study Based on Multifractal Analysis
Authors: Shao Ying-Hui , Liu Ying-Lin , Yang Yan-Hong 
Published: September 2022

The ongoing COVID-19 shocked financial markets globally, including China’s crude oil future market, which is the third-most traded crude oil futures after WTI and Brent. As China’s first crude oil futures are accessible to foreign investors, the Shanghai crude oil futures (SC) have attracted significant interest since launch at the Shanghai International Energy Exchange. The impact of COVID-19 on the new crude oil futures is an important issue for investors and policy makers. Therefore, this paper studies the short-term influence of COVID-19 pandemic on SC via multifractal analysis. We compare the market efficiency of SC before and during the pandemic with the multifractal detrended fluctuation analysis and other commonly used random walk tests. Then, we generate shuffled and surrogate data to investigate the components of multifractal nature in SC. And we examine cross-correlations between SC returns and other financial assets returns as well as SC trading volume changes by the multifractal detrended cross-correlation analysis. The results show that market efficiency of SC and its cross-correlations with other assets increase significantly after the outbreak of COVID-19. Besides that, the sources of its multifractal nature have changed since the pandemic. The findings provide evidence for the short-term impacts of COVID-19 on SC. The results may have important implications for assets allocation, investment strategies and risk monitoring.
Laboratory Test Predictors for Major Bleeding in Elderly (≥80 Years) Patients With Nonvalvular Atrial Fibrillation Treated With Edoxaban 15 mg: Sub‐Analysis of the ELDERCARE‐AF Trial
Authors: Mikami Takeshi , Hirabayashi Kagami , Okawa Keisuke , Betsuyaku Tetsuo , Watanabe Saori , Imamura Yuki , Tanizawa Kimihiko , Hayashi Takuya , Akao Masaharu , Yamashita Takeshi , Okumura Ken 
Published: September 2022

Background
We investigated the predictors related to major bleeding events during treatment with edoxaban 15 mg in patients aged ≥80 years with nonvalvular atrial fibrillation and high bleeding risk, for whom standard oral anticoagulants are inappropriate, focusing on standard laboratory tests related to bleeding.

Methods and Results
This was a prespecified subanalysis of the on‐treatment analysis set of the ELDERCARE‐AF (Edoxaban Low‐Dose for Elder Care Atrial Fibrillation Patients) trial. Major bleeding was the primary safety end point. The event rates were calculated according to prespecified characteristics at baseline. A total of 984 Japanese patients were randomly assigned to edoxaban 15 mg or placebo (n=492, each). During the study period, 20 and 11 major bleeding events occurred in the edoxaban and placebo groups, respectively. The adjusted analysis revealed that hemoglobin <12.3 g/dL (adjusted hazard ratio [aHR], 3.57 [95% CI, 1.10–11.55]) and prothrombin time ≥12.7 seconds; (aHR, 2.89 [95% CI, 1.05–8.02]) independently predicted major bleeding, while creatinine clearance <30 mL/min showed a tendency towards an increase in major bleeding (aHR, 2.68; 95% CI, 0.96–7.46). In patients treated with edoxaban lacking these 3 risk factors, no major bleeding occurred; major bleeding event rates increased with each risk factor. Patients with 3 risk factors were significantly more likely to have a major bleeding event at 11.05%/year (HR, 7.15 [95% CI, 1.92–26.71]).

Conclusions
In elderly patients with nonvalvular atrial fibrillation with high bleeding risk, baseline hemoglobin <12.3 g/dL, prothrombin time ≥12.7 seconds, and creatinine clearance <30 mL/min may predict major bleeding during treatment with edoxaban 15 mg.

Registration

URL: ELDERCARE‐AF
https://www.clinicaltrials.gov
; Unique number: NCT02801669.
Factors Contributing to Sex Differences in Health‐Related Quality of Life After Ischemic Stroke: BASIC (Brain Attack Surveillance in Corpus Christi) Project
Authors: Phan Hoang T. , Reeves Mathew J. , Gall Seana , Morgenstern Lewis B. , Xu Yuliang , Lisabeth Lynda D. 
Published: September 2022

Background
Women have been reported to have worse health‐related quality of life (HRQoL) following stroke than men, but uncertainty exists over the reasons for the sex difference.

Methods and Results
We included all ischemic strokes registered with the BASIC (Brain Attack Surveillance in Corpus Christi) project (May 2010–December 2016), a population‐based stroke study, who completed a 90‐day outcome interview. Information on baseline characteristics was obtained from medical records and in‐person interviews. HRQoL was measured by the 12‐item short‐form Stroke Specific Quality of Life Scale. Multivariable Tobit regression was used to estimate the mean difference in overall HRQoL scores (range, 1–5; higher indicating better HRQoL) between sexes and to identify contributing factors to the differences. We included 1061 cases with complete data on HRQoL and covariates (median age, 67 years; 51% women). In unadjusted analyses, women had poorer overall HRQoL than men (mean difference, −0.26 [95% CI, −0.40 to −0.13]). Contributors to this difference included sociodemographic/prestroke factors (eg, age, race and ethnicity, prestroke function), risk factors/comorbidities (eg, history of stroke, Alzheimer disease/dementia), and initial stroke severity. Sociodemographic/prestroke factors explained 62% of the sex difference (mean difference, −0.08 [95% CI, −0.21 to 0.04]). In a fully adjusted model that included adjustment for all confounding factors, the sex difference was eliminated and became nonsignificant (mean difference, −0.03 [95% CI, −0.16 to 0.09]).

Conclusions
Poorer HRQoL in women compared with men was observed and explained by the combination of sociodemographic and prestroke factors, including physical function before stroke and stroke severity. The findings suggest potential subgroups of women who might benefit from more targeted interventions before and after stroke to improve HRQoL.
Global Burden, Regional Differences, Trends, and Health Consequences of Medication Nonadherence for Hypertension During 2010 to 2020: A Meta‐Analysis Involving 27 Million Patients
Authors: Lee Eric K. P. , Poon Paul , Yip Benjamin H. K. , Bo Yacong , Zhu Meng‐Ting , Yu Chun‐Pong , Ngai Alfonse C. H. , Wong Martin C. S. , Wong Samuel Y. S. 
Published: September 2022

Background
Nonadherence to antihypertensive medications is the leading cause of poor blood pressure control and thereby cardiovascular diseases and mortality worldwide.

Methods and Results

We investigated the global epidemiology, regional differences, and trend of antihypertensive medication nonadherence via a systematic review and meta‐analyses of data from 2010 to 2020. Multiple medical databases and
clinicaltrials.gov
were searched for articles. Observational studies reporting the proportion of patients with anti‐hypertensive medication nonadherence were included. The proportion of nonadherence, publication year, year of first recruitment, country, and health outcomes attributable to antihypertensive medication nonadherence were extracted. Two reviewers screened abstracts and full texts, classified countries according to levels of income and locations, and extracted data. The Joanna Briggs Institute prevalence critical appraisal tool was used to rate the included studies. Prevalence meta‐analyses were conducted using a fixed‐effects model, and trends in prevalence were analyzed using meta‐regression. The certainty of evidence concerning the effect of health consequences of nonadherence was rated according to Grading of Recommendations, Assessment, Development and Evaluations. A total of 161 studies were included. Subject to different detection methods, the global prevalence of anti‐hypertensive medication nonadherence was 27% to 40%. Nonadherence was more prevalent in low‐ to middle‐income countries than in high‐income countries, and in non‐Western countries than in Western countries. No significant trend in prevalence was detected between 2010 and 2020. Patients with antihypertensive medication nonadherence had suboptimal blood pressure control, complications from hypertension, all‐cause hospitalization, and all‐cause mortality.

Conclusions
While high prevalence of anti‐hypertensive medication nonadherence was detected worldwide, higher prevalence was detected in low‐ to middle‐income and non‐Western countries. Interventions are urgently required, especially in these regions. Current evidence is limited by high heterogeneity.

Registration

URL:
www.crd.york.ac.uk/prospero/
; Unique identifier: CRD42021259860.
Bereavement and Prognosis After a First Acute Myocardial Infarction: A Swedish Register‐Based Cohort Study
Authors: Wei Dang , Janszky Imre , Ljung Rickard , Fang Fang , Li Jiong , László Krisztina D. 
Published: September 2022

BACKGROUND
Despite accumulating evidence suggesting that bereavement is associated with increased risks of cardiovascular morbidity and mortality, the association between bereavement and prognosis after acute myocardial infarction (AMI) has not been well documented. We investigated the association by using Swedish register data.

METHODS AND RESULTS
We studied 266 651 patients with a first AMI included in the SWEDEHEART (Swedish Web‐system for Enhancement and Development of Evidence‐based care in Heart disease Evaluated According to Recommended Therapies) quality register from 1991 to 2018. We obtained information on bereavement (ie, death of a partner, child, grandchild, sibling, or parent), on primary (nonfatal recurrent AMI and death attributed to ischemic heart disease) and secondary outcomes (total mortality, heart failure, and stroke) and on covariates from several national registers. The association was analyzed using Poisson regression. The bereaved patients had a slightly increased risk of the primary outcome; the corresponding risk ratio (RR) was 1.02 (95% CI, 1.00–1.04). An increased risk was noted any time bereavement occurred, except if the loss was in the year after the first AMI. The association was strongest for the loss of a partner, followed by the loss of a child, grandchild, sibling, or parent. We also observed increased risks for total mortality (RR, 1.14 [95% CI, 1.12–1.16]), heart failure (RR, 1.05 [95% CI, 1.02–1.08]), and stroke (RR, 1.09 [95% CI, 1.05–1.13]) following bereavement.

CONCLUSIONS
Bereavement was associated with an increased risk of poor prognosis after a first AMI. The association varied by the relationship to the deceased.