bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of the Effects of High Temperature Treatment on Quasi-Static Mechanical Characteristics of EMWM Materials
Authors: Ma Yanhong , Liang Tianyu , Hong Jie 
Published: September 2021

Abstract
This paper investigates the influence of high temperature treatment processes on the mechanical characteristics of entangled metallic wire materials (EMWM) via quasi-static compression tests. The treatment methods including high-temperature treatment and high-temperature with loading treatment were tested. The variation effects of size in molding direction, tangent modulus and loss factor were obtained by contrast results of EMWM specimens via the treatment processes with initial performance. The results indicate that the treatment processes proposed in this study can significantly improve the mechanical properties of EMWM materials and have a wide range of application for EMWM specimens with different structural parameters. After the treatment processes, the size of specimens in molding direction decreased slightly, the tangent modulus increased significantly, and the loss factor decreased slightly. With the increase of treatment temperature, the variation of mechanical parameters intensified. For EMWM specimens with different relative densities and heights, the treatment processes still have a significant improvement effect on quasi-static mechanical properties. Finally, the secondary molding theory is carried out to explain the influence of high temperature treatment process on EMWM’s dimensions and mechanical properties. The effects of treatment temperature and repetition times obtained in this study are relevant to the design of treatment processes for EMWM materials.
Experimental and Numerical Similitude Study Using a Novel Turbocompressor Test Facility Operating With Helium-Neon Gas Mixtures
Authors: Podeur Maxime , Vogt Damian M. 
Published: September 2021

Abstract
A novel turbocompressor test facility has been designed for helium-neon gas mixtures and its specific features are presented. To account for the heat transfer originating from the motor coolant, a surrogate model has been derived. By combining these results with additional numerical ones, a similitude study is conducted quantifying the individual effects and contributions on efficiency of the Reynolds number, tip Mach number and specific heat ratio. Decoupling the effect of the different parameters shows that their respective contribution on efficiency variation is highly correlated to the Reynolds number actual value. The negative contribution of the tip Mach number and the positive effect of Reynolds number can be used to explain the efficiency variation with increasing tip Mach number. Specific heat ratio variation leads to minor changes in polytropic efficiency except at low tip Mach numbers.
Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications
Authors: Alvarez-Regueiro Eva , Barrera-Medrano Esperanza , Martinez-Botas Ricardo , Rajoo Srithar 
Published: September 2021

Abstract
This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.
Reducing Uncertainty in the Onset of Combustion Instabilities Using Dynamic Pressure Information and Bayesian Neural Networks
Authors: McCartney Michael , Sengupta Ushnish , Juniper Matthew 
Published: September 2021

Abstract
Modern, low emission combustion systems with improved fuel-air mixing are more prone to combustion instabilities and therefore use advanced control methods to balance minimum NOx emissions and and the presence of thermoacoustic combustion instabilities. The exact operating conditions at which the system encounters an instability is uncertain because of sources of stochasticity, such as turbulent combustion, and the influence of hidden variables, such as un-measured wall temperatures or differences in machine geometry within manufacturing tolerances. Practical systems tend to be more elaborate than laboratory systems and tend to have less instrumentation, meaning that they suffer more from uncertainty induced by hidden variables. In many commercial systems, the only direct measurement of the combustor comes from a dynamic pressure sensor. In this study we train a Bayesain Neural Network (BNN) to predict the probability of onset of thermoacoustic instability at various times in the future, using only dynamic pressure measurements and the current operating condition. We show that, on a practical system, the error in the onset time predicted by the BNNs is 45% lower than the error when using the operating condition alone and more informative than the warning provided by commonly used precursor detection methods. This is demonstrated on two systems: (i) a premixed hydrogen/methane annular combustor, where the hidden variables are wall temperatures that depend on the rate of change of operating condition, and (ii) full scale prototype combustion system, where the hidden variables arise from differences between the systems.
Validating Soot Models in LES of Turbulent Flames: The Contribution of Soot Subgrid Intermittency Model to The Prediction of Soot Production in an Aero-Engine Model Combustor
Authors: Pereira Tardelli Lívia , Darabiha Nasser , Veynante Denis , Franzelli Benedetta 
Published: September 2021

Abstract
Predicting soot production in industrial systems using an LES approach represents a great challenge. Besides the complexity in modeling the multi-scale physicochemical soot processes and their interaction with turbulence, the validation of newly developed models is critical under turbulent conditions. This work illustrates the difficulties in evaluating model performances specific to soot prediction in turbulent flames by considering soot production in an aero-engine combustor. It is proven that soot production occurs only for scarce local gaseous conditions. Therefore, to obtain a statistical representation of such rare soot events, massive CPU resources would be required. For this reason, evaluating soot model performances based on parametric studies, i.e., multiple simulations, as classically done for purely gaseous flames, is CPU high-demanding for sooting flames. Then, a new strategy to investigate modeling impact on the solid phase is proposed. It is based on a unique simulation, where the set of equations describing the solid phase are duplicated. One set accounts for the reference model, while the other set is treated with the model under the scope. Assuming neglected solid phase retro-coupling on the gas phase, the soot scalars from both sets experience the same unique temporal and spatial gas phase evolution isolating the soot model effects from the uncertainties on gaseous models and numerical sensitivities. Finally, the strategy capability is proven by investigating the contribution of the soot subgrid intermittency model to the prediction of soot production in the DLR burner.
The Development of Turboexpander-Generators for Gas Pressure Letdown Part II: Economic Analysis
Authors: Liu Jeremy , Khatri Rasish , Sarhan Freddie , Blumber Eric 
Published: September 2021

Abstract
A family of “flow-through” turboexpander-generators (TEGs) has been developed by Calnetix Technologies for hydrogen and natural gas pressure letdown applications. A flow-through TEG includes an axial expansion turbine and can be installed directly between two flanges of an existing pipeline. TEGs can be used to generate power throughout the hydrogen and natural gas transmission infrastructure using existing pressure differentials wherever a Joule-Thomson valve is located. These can be upstream, at terminal stations, and downstream, at governor stations. The expander drives a synchronous permanent magnet high-speed generator supported by active magnetic bearings. This paper describes the innovative axial flow-through system architecture, including the use of process gas for cooling the generator rotor and stator. The primary focus of the paper is the economic analysis of the application. Various TEG subsystem design choices and their impact on cost are discussed, including the generator, bearing, expander wheel, seal, and touchdown bearing resilient mount designs. A payback analysis shows that the natural gas TEG has a payback of 2.1 years when a heat exchanger is required for preheating the gas and 1.9 years when waste heat can be used. The hydrogen TEG has a payback of 2.0 years, and does not require external preheating. Finally, a comparison of this technology with other clean energy solutions is presented, using the Levelized Cost of Electricity (LCOE) formulation. The analysis confirms that the LCOE of the expander-generator ($0.40 per megawatt-hour) compares favorably with other types of conventional and renewable energy technologies on a cost basis.
Fast Reconstruction Method of the Stress Field for the Steam Turbine Rotor Based on Deep Fully Convolutional Network
Authors: Guo Ding , Liu Tianyuan , Zhang Di , Xie Yonghui 
Published: September 2021

Abstract
Since it is difficult to directly measure the transient stress of a steam turbine rotor in operation, a rotor stress field reconstruction model based on deep fully convolutional network for the start-up process is proposed. The stress distribution in the rotor can be directly predicted based on the temperature of a few measurement points. First, the finite element model is used to accurately simulate the temperature and stress field of the rotor start-up process, generating training data for the deep learning method. Next, data of only 15 temperature measurement points are arranged to predict the stress distribution in critical area of the rotor surface, with the accuracy (R2-score) reaching 0.997. The time cost of the trained neural network model at a single case is 1.42s in CPUs and 0.11s in GPUs, shortened by 97.3% and 99.8% with comparison to finite element analysis, respectively. In addition, the influence of the number of temperature measurement points and the training size are discussed, verifying the stability of the model. With the advantages of fast calculation, high accuracy and strong stability, the fast reconstruction model can effectively realize the stress prediction during start-up processes, resulting in the possibility of real-time diagnosis of rotor strength in operation.
The Nature of Finger Enslaving: New Results and Their Implications
Authors: Abolins Valters , Latash Mark L. 
Published: September 2021

We present a review on the phenomenon of unintentional finger action seen when other fingers of the hand act intentionally. This phenomenon (enslaving) has been viewed as a consequence of both peripheral (e.g., connective tissue links and multifinger muscles) and neural (e.g., projections of corticospinal pathways) factors. Recent studies have shown relatively large and fast drifts in enslaving toward higher magnitudes, which are not perceived by subjects. These and other results emphasize the defining role of neural factors in enslaving. We analyze enslaving within the framework of the theory of motor control with spatial referent coordinates. This analysis suggests that unintentional finger force changes result from drifts of referent coordinates, possibly reflecting the spread of cortical excitation.
Can high-intensity interval training improve mental health outcomes in the general population and those with physical illnesses? A systematic review and meta-analysis
Authors: Martland Rebecca , Korman Nicole , Firth Joseph , Vancampfort Davy , Thompson Trevor , Stubbs Brendon 
Published: September 2021

ObjectiveHigh-intensity interval training (HIIT) is a safe and feasible form of exercise. The aim of this meta-analysis was to investigate the mental health effects of HIIT, in healthy populations and those with physical illnesses, and to compare the mental health effects to non-active controls and other forms of exercise.DesignRandom effects meta-analyses were undertaken for randomised controlled trials (RCTs) comparing HIIT with non-active and/or active (exercise) control conditions for the following coprimary outcomes: mental well-being, symptoms of depression, anxiety and psychological stress. Positive and negative affect, distress and sleep outcomes were summarised narratively.Data sourcesMedline, PsycINFO, Embase and CENTRAL databases were searched from inception to 7 July 2020.Eligibility criteria for selecting studiesRCTs that investigated HIIT in healthy populations and/or those with physical illnesses and reported change in mental well-being, depression, anxiety, psychological stress, positive/negative affect, distress and/or sleep quality.ResultsFifty-eight RCTs were retrieved. HIIT led to moderate improvements in mental well-being (standardised mean difference (SMD): 0.418; 95% CI: 0.135 to 0.701; n=12 studies), depression severity (SMD: –0.496; 95% CI: −0.973 to −0.020; n=10) and perceived stress (SMD: −0.474; 95% CI: −0.796 to −0.152; n=4) compared with non-active controls, and small improvements in mental well-being compared with active controls (SMD:0.229; 95% CI: 0.054 to 0.403; n=12). There was a suggestion that HIIT may improve sleep and psychological distress compared with non-active controls: however, these findings were based on a small number of RCTs.ConclusionThese findings support the use of HIIT for mental health in the general population.Level of evidenceThe quality of evidence was moderate-to-high according to the Grading of Recommendations Assessment, Development and Evaluation) criteria.PROSPERO registration numberCRD42020182643
Association between tissue oxygenation and myocardial injury in patients undergoing major spine surgery: a prospective cohort study
Authors: Bernholm Katrine Feldballe , Meyhoff Christian S. , Bickler Philip 
Published: September 2021

ObjectiveTo describe the association between intraoperative tissue oxygenation and postoperative troponin elevation in patients undergoing major spine surgery. We hypothesised that a decrease in intraoperative skeletal muscle tissue oxygenation (SmO2) was associated with the peak postoperative cardiac troponin value.DesignThis is a prospective cohort study.SettingSingle-centre, University of California San Francisco Medical Center.ParticipantsSeventy adult patients undergoing major elective spine surgery.Primary and secondary outcome measuresHigh-sensitivity troponin T (hsTnT) was measured in plasma preoperatively and on the first and second day after surgery to assess the primary outcome of peak postoperative hsTnT. Secondary outcomes included MINS and intensive care unit (ICU) admission within 30 days. Skeletal cerebral tissue oxygenation and SmO2was measured continuously with near-infrared spectroscopy during surgery. The primary exposure variable was time-weighted area under the curve (TW AUC) for SmO2.ResultsMean age was 65 (33–85) years and 59% were female. No significant association was found between TW AUC for SmO2and peak hsTnT (Spearman’s correlation, rs=0.17, p=0.16). A total of 28 (40%) patients had MINS. ICU admission occurred in 14 (40%) in lower vs 25 (71%) in upper half of patients based on TW AUC for SmO2, p=0.008.ConclusionsDecrease in SmO2was not a statistically significant predictor for peak troponin value following major spine surgery but is a potential predictor for other postoperative complications.Trial registration numberNCT03518372.
‘NOPAIN-ROP’ trial: Intravenous fentanyl and intravenous ketamine for pain relief during laser photocoagulation for retinopathy of prematurity (ROP) in preterm infants: A randomised trial
Authors: Madathil Shamnad , Thomas Deena , Chandra Parijat , Agarwal Ramesh , Sankar M Jeeva , Thukral Anu , Deorari Ashok 
Published: September 2021

ObjectivesTo investigate if intravenous fentanyl or intravenous ketamine can provide adequate analgesia in preterm infants undergoing laser photocoagulation for retinopathy of prematurity (ROP).DesignOpen-label randomised trial.SettingTertiary care institution.ParticipantsPreterm infants who underwent laser photocoagulation for ROP.InterventionsInfants were randomised to receive fentanyl as intravenous bolus dose of 2 µg/kg, followed by an intravenous infusion of 1 µg/kg/hour increased to a maximum of 3 µg/kg/hour or intravenous ketamine as bolus dose of 0.5 mg/kg, followed by further intermittent intravenous bolus doses of 0.5 mg/kg to a maximum of 2 mg/kg in the initial phase and intravenous fentanyl (bolus of 2 µg/kg followed by infusion of 2 µg/kg/hour to a maximum of 5 µg/kg/hour) or intravenous ketamine (bolus dose of 1 mg/kg followed by intermittent bolus doses of 0.5 mg/kg to a maximum of 4 mg/kg) in the revised regimen phase.Main outcome measuresProportion of infants with adequate analgesia defined as the presence of both: (1) all the Premature Infant Pain Profile-Revised scores measured every 15 min less than seven and (2) proportion of the procedure time the infant spent crying less than 5%.Secondary outcomes included apnoea, cardiorespiratory or haemodynamic instability, feed intolerance and urinary retention requiring catheterisation during and within 24 hours following the procedure.ResultsA total of 97 infants were randomised (fentanyl=51, ketamine=46). The proportions of infants with adequate analgesia were 16.3% (95% CI 8.5% to 29%) with fentanyl and 4.5% (95% CI 1.3% to 15.1%) with ketamine. Ten infants (19.6%) in the fentanyl group and seven infants (15.2%) in the ketamine group had one or more side effects. In view of inadequate analgesia with both the regimens, the study steering committee recommended using a higher dose of intravenous fentanyl and intravenous ketamine. Consequently, we enrolled 27 infants (fentanyl=13, ketamine=14). With revised regimens, the proportions of infants with adequate analgesia were higher: 23.1% (95% CI 8.2% to 50.2%) with fentanyl and 7.1% (95% CI 1.3% to 31.5%) with ketamine. However, higher proportions of infants developed apnoea (n=4; 30.7%), need for supplemental oxygen (n=5, 38.4%) and change in cardiorespiratory scores (n=7; 53.8%) with fentanyl but none with ketamine.ConclusionsFentanyl-based and ketamine-based drug regimens provided adequate analgesia only in a minority of infants undergoing laser photocoagulation for ROP. More research is needed to find safe and effective regimens that can be employed in resource constrained settings.Trial registration numberCTRI/2018/03/012878.
Effect of ethnicity and other sociodemographic factors on attendance at diabetic eye screening: a 12-month retrospective cohort study
Authors: Olvera-Barrios Abraham , Seltene Michael , Heeren Tjebo F C , Chambers Ryan , Bolter Louis , Tufail Adnan , Owen Christopher G , Rudnicka Alicja R , Egan Catherine , Anderson John 
Published: September 2021

ObjectivesTo examine the association of sociodemographic characteristics with attendance at diabetic eye screening in a large ethnically diverse urban population.DesignRetrospective cohort study.SettingScreening visits in the North East London Diabetic Eye Screening Programme (NELDESP).Participants84 449 people with diabetes aged 12 years or older registered in the NELDESP and scheduled for screening between 1 April 2017 and 31 March 2018.Main outcome measureAttendance at diabetic eye screening appointments.ResultsThe mean age of people with diabetes was 60 years (SD 14.2 years), 53.4% were men, 41% South Asian, 29% White British and 17% Black; 83.4% attended screening. Black people with diabetes had similar levels of attendance compared with White British people. However, South Asian, Chinese and 'Any other Asian' background ethnicities showed greater odds of attendance compared with White British. When compared with their respective reference group, high levels of deprivation, younger age, longer duration of diabetes and worse visual acuity, were all associated with non-attendance. There was a higher likelihood of attendance per quintile improvement in deprivation (OR, 1.06; 95% CI, 1.03 to 1.08), with increasing age (OR per decade, 1.17; 95% CI, 1.15 to 1.19), with better visual acuity (OR per Bailey-Lovie chart line 1.12; 95% CI, 1.11 to 1.14) and with longer time of NELDESP registration (OR per year, 1.02; 95% CI, 1.01 to 1.03).ConclusionEthnic differences in diabetic eye screening uptake, though small, are evident. Despite preconceptions, a higher likelihood of screening attendance was observed among Asian ethnic groups when compared with the White ethnic group. Poorer socioeconomic profile was associated with higher likelihood of non-attendance for screening. Further work is needed to understand how to target individuals at risk of non-attendance and reduce inequalities.