bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of the intraoperative blood loss in dogs undergoing enucleation
Authors: Lenihan Emer , Baines Stephen J. , Linn‐Pearl Rose N. , Grundon Rachael A. , Carrozza Rossella , Stevens Elizabeth J. , Heinrich Christine L. , Walsh Karen 
Published: November 2022

AbstractPurposeTo quantify the surgical blood loss during canine enucleation and to investigate the relationship between this and any patient, surgical, and anesthetic factors.MethodsA prospective observational analysis was conducted on 121 client‐owned dogs (130 eyes) undergoing enucleation at a referral ophthalmology clinic. Blood loss was estimated by the gravimetric method (weight difference between dry and blood‐containing surgical materials) to provide absolute blood loss (ABL) in milliliters, expressed as a percentage of circulating blood volume, to establish relative blood loss (RBL).ResultsMedian ABL was 12 ml (1.6–116 ml), and median RBL was 1.3% (0.1%–6.7%). A higher RBL was associated with the following: use of a bupivacaine splash block versus retrobulbar nerve block (1.9 vs. 1%; p < .001), transpalpebral versus subconjunctival approach (2.2 vs. 1.3%; p = .003), and small versus large breed dogs (1.7% vs. 1.1%; p = .001). Both ABL and RBL differed significantly between surgeons. There was no significant difference in hemorrhage associated with the presence of ocular hypertension, systemic illness, surgical time, administration of meloxicam or choice of pre‐medicant (acepromazine vs medetomidine). No dog required supportive intervention in response to surgical hemorrhage.ConclusionsThis study has established a surgical blood loss estimate for dogs undergoing enucleation at an ophthalmology referral centre. Subconjunctival enucleation may be preferred for patients at greater risk of haemodynamic complications.
Degradation-Aware Ensemble of Diverse Predictors for Remaining Useful Life Prediction
Authors: Nemani Venkat , Thelen Adam , Hu Chao , Daining Steve 
Published: November 2022

Abstract
A traditional ensemble approach to predicting the remaining useful life (RUL) of equipment and other assets has been constructing data-driven and model-based ensembles using identical predictors. This ensemble approach may perform well on quality data collected from laboratory tests but may ultimately fail when deployed in the field because of higher-than-expected noise, missing measurements, and different degradation trends. In such work environments, the high similarity of the predictors can lead to large under/overestimates of RUL, where the ensemble is only as accurate as the predictor which under/overestimated RUL the least. In response to this, we investigate whether an ensemble of diverse predictors might be able to predict RUL consistently and accurately by dynamically aggregating the predictions of various algorithms which are found to perform differently under the same conditions. We propose improving ensemble model performance by (1) using a combination of diverse learning algorithms which are found to perform differently under the same conditions and (2) training a data-driven model to adaptively estimate the prediction weight each predictor receives. The proposed methods are compared to three existing ensemble prognostics methods on open-source run-to-failure datasets from two popular systems of prognostics research: lithium-ion batteries and rolling element bearings. Results indicate the proposed ensemble method provides the most consistent prediction accuracy and uncertainty estimation quality across multiple test cases, whereas the individual predictors and ensembles of identical predictors tend to provide overconfident predictions.
The Phase Behaviors of Confined Shale Fluids Considering Adsorption Effect
Authors: Du Fengshuang , Jiang Shu 
Published: November 2022

AbstractThe molecular adsorption in nano-scale shale pores results in the reduction of effective pore volume and further strengthens the confinement effect. This study aims at examining the adsorption effect coupled with confinement effects on phase behaviors of shale fluids. First, a modified extended Langmuir formula was developed to calculate the adsorption amount for a multi-component shale mixture. A modified cubic Peng–Robinson equation of state was proposed, and the occupied volume by the adsorbed phase was taken into account. The saturation pressures and fluid properties under the confinement effects and adsorption isotherms were examined. In order to examine the change of phase properties during a gas injection process in a shale condensate reservoir, we gradually increase the mole fractions of N2 or CO2 in shale condensate mixtures by coupling with confinement effects. We found that the thickness of the adsorption film reduces the effective pore throat, leading to intensified confinement effects and smaller bubble point pressures. When the gas adsorption layer is considered, a more significant decrease in density and viscosity is observed. The critical pressure of the condensate fluids increases and the critical temperature decreases with the continuous N2 injection. Contrary to N2 injection, the critical pressure decreases and the critical temperature moves upwards with CO2 injection. For condensate that accumulates in nano-pores (e.g., r ≤ 6 nm), the condensate fluid always exists in gas status during the gas injection and the subsequent production processes.
An Experimental Investigation on the Dynamic Response Variability of a Turbine Blade With Mid-Span Dampers
Authors: Ferhatoglu Erhan , Botto Daniele , Zucca Stefano 
Published: November 2022

Abstract
This paper addresses two main subjects. Firstly, a novel test setup is described to experimentally study the nonlinear dynamic behavior of a turbine blade coupled with two mid-span dampers. To this end, a representative turbine blade and mid-span friction dampers are originally designed, and they are assembled to a special test rig which has been previously developed at Politecnico di Torino. Secondly, 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 non-unique contact forces that provide different static force equilibria on the damper. This outcome is further supported by the qualitative illustration of hysteresis cycles. The current study contributes to the understanding of the response repeatability linked to the non-uniqueness of friction forces.
Aerodynamic Forcing Models for Compressor Aeromechanics
Authors: Hernley Valerie , Jemcov Aleksandar , Morris Scott C. 
Published: November 2022

Abstract
The present work was focused on formalizing a mathematical description of aerodynamic forcing mechanisms relevant to compressor blade vibration. The hypothesis was that the functional form of the aerodynamic forcing functions could categorize the various aerodynamic forcing mechanisms. Based on this hypothesis, the multitude of aerodynamic forcing mechanisms relevant to compressor aeromechanics was divided into three categories: 1) external forcing, 2) blade-row aerodynamic forcing, and 3) motion-dependent forcing. Modal forcing models for each category were presented, including a novel model for rotating stall effects. Simulations for each category demonstrated distinct and unique temporal characteristics of the response to different aerodynamic forcing mechanisms. Good agreement with experimental data supports using these temporal characteristics to identify the physical forcing mechanisms present in measured blade vibration data.
Computation of the Unsteady Loading on a Fan Blade Due to Inlet Distortion Using Body Force Methodology
Authors: Bouhafid Younes , Berthelon Thomas 
Published: November 2022

Abstract
The latest aero-propulsion configurations are characterized by a strong aerodynamic interaction between the engine and its environment. This interaction results in unsteady loads perceived by the fan leading to vibrations. In order to ensure the mechanical integrity of the blades, engine designers must evaluate these vibration levels very early in the design phases. To do so, the classic solution consists in running full-annulus U-RANS calculations to compute unsteady loading on the blade and then deduce the fan’s forced response. However, such method can be computationally expensive and is consequently not adapted for large parametric studies conducted during the design phase of a blade. This paper presents a new method for calculating the forced response of a fan based on the use of body force calculations, which has a significantly lower computational cost compared to bladed U-RANS calculations. The main idea of the body force method is to replace the blades by source terms in the Navier-Stokes equations inside the volume swept by the fan. First, the application framework of the method is detailed. Then, the key step of the method which consists in computing the generalized aerodynamic forces from a body force calculation is presented and where the main idea involves concentrating the body force terms on the blade camber surface. A validation of the method is then proposed using a comparison with high fidelity U-RANS calculations for a BLI-like inlet distortion. It is found that the body force methodology reproduces the harmonic content of the computed generalized aerodynamic forces with a relatively good accuracy. Finally, an example of use of this method in a design context is presented as new body force calculations are run for two other inlet distortions that can occur in the takeoff phase: the ground vortex and the inlet flow separation.
Reduced Order Modeling of Forced Response in a Multistage Compressor Under Mistuning and Aerocoupling
Authors: Maroldt Niklas , Seume Joerg R. , Schwerdt Lukas , Panning von-Scheidt Lars , Wallaschek Jörg , Berger Ricarda , Rolfes Raimund 
Published: November 2022

Abstract
Vibration amplitudes and fatigue life in multistage turbomachinery are commonly estimated by an isolated investigation of the individual stages. Research is currently extending the scope to include inter-stage coupling of structural dynamics and aeroelasticity, i.e. aerodynamic coupling. These two effects have been shown to significantly influence blade vibrations. For safe operation of modern blisk blading with its lower structural damping due to the elimination of frictional contacts at the blade roots, an accurate prediction of the vibration behavior in multistage configurations with mistuning is necessary to avoid high cycle fatigue (HCF) failures.
In this paper, a cyclic Craig-Bampton reduction method with a priori interface reduction for multistage rotors is extended to handle aeroelastic effects. These reduced order models efficiently predict forced response in multistage applications. Aeroelastic multistage simulations are carried out using the harmonic balance method to account for the stage interactions and yield damping and stiffness coefficients, as well as modal excitation forces. Small structural mistuning is projected onto the tuned system modes of the rotor. The reduced order approach is applied to a two-stage compressor configuration. Monte Carlo simulations show the sensitivity of vibration amplitudes to the aeroelastic coupling for mistuning. The aeroelastic inter-stage coupling is found to originate mainly from acoustic mode propagation between the rotor stages. The fatigue of rotor blades is significantly affected by multistage interaction since vibration amplitudes increase due to the superposition of the vibration responses of multiple modes. This leads to the conclusion that aeroelastic multistage effects need to be incorporated in future design procedures to allow for an accurate prediction of fatigue life of compressor rotors.
Experimental Investigation of Friction Damping in Blade Root Joints
Authors: Botto Daniele , Iannotti Veronica , Cuccovillo Federica 
Published: November 2022

Abstract
The design of disk assemblies requires the capability to predict their dynamic behavior. To achieve this objective, knowledge of friction damping on the contact between blade and disk is of paramount importance. This paper proposes an experimental technique to measure the loss factor and the dynamics, in terms of natural frequencies, of blade-disk attachment. The free decay is used to infer the dynamic parameters from dummy blades. The identification method is based on the Hilbert transform that allows extracting the dynamic parameters from non-linear system. This paper shows the test rig utilized in the experimental analysis and details the excitation system used to displace the dummy blade. This system must be a real or a “virtual” non-contact system to avoid injecting external damping into the blade under test. Tests were performed on both a dovetail and a fir-tree type attachments. On the dovetail, tests were performed both with dry contact surfaces and with contact surfaces covered by a film of lubricant to achieve a low coefficient of friction. This low coefficient of friction better simulates dry surfaces at high temperatures, as friction coefficients decrease with temperatures. This paper presents the results obtained on the first and second bending mode. The experimental results show the loss factor and the natural frequency for different axial loads. The measured loss factor depends on the amplitude of vibrations. As predicted with theoretical analyses the loss factor shows a maximum then approaching zero for large amplitude of vibrations. As a rule, it decreases with increasing centrifugal loads.
Aerodynamic Damping Predictions During Compressor Surge: A Numerical Comparison Between a Half and Full Transient Approach
Authors: Reiber Christoph , Chenaux Virginie Anne , Belz Joachim 
Published: November 2022

Abstract
The prediction of the aerodynamic damping during compressor surge is a challenging task, because the flow is continuously evolving along the four surge cycle phases: Pressurization (PR), Flow-Breakdown (FB), Reversed Flow (RF) and Regeneration (RG) and complex flow conditions like shocks and separations occur.
Damping predictions with current existing methods typically consist of two steps. In the first step a modified numerical model is used to simulate transient surge cycles. In the second step, damping analyses are performed for multiple timesteps along the surge cycle phases, which are then assumed as quasi-steady. The damping simulation can be performed using nonlinear or linear approaches. If shocks or separations occur, the latter yields inaccuracies in the flow and thus in the damping predictions.
A new approach was developed to take into account and improve these inaccuracies. This new method includes the damping prediction within the transient surge simulation. Thus, all surge cycle phases and the continuously evolving flow conditions are considered and nonlinear simulations are performed to account for shocks and separations. The results of this new method are presented and compared to the former method.
Simulation and Validation of Creep Damage on Grain Boundary of Polycrystalline Alloy 247
Authors: Nguyen Tuan Duc , Mäde Lucas , Kulawinski Dirk 
Published: November 2022

Abstract
In this paper, the cavitation process on a grain boundary in polycrystalline Alloy 247 is simulated and modelled. The cavitation process includes mechanisms such as nucleation, growth and coalescence of creep pores and was used for characterization of polycrystalline Alloy 247 in terms of creep damage and especially creep pore sizes. Two main parameters were defined that are either responsible for pore nucleation or pore growth and that are calculated from simulation variables and material coefficients. Therefore, a Design of Experiment (DOE) was carried out to identify the effect of each material coefficient and simulation variable on the cavitation process as well as the ranges of the main parameters for pore nucleation and pore growth. As a result of the investigation, a series of Monte Carlo simulations was run with designated combinations of main parameters within the identified range. The simulation results were used as training and test data to create a model by machine learning methods. Different machine learning methods such as neural network, random forest tree and k-nearest neighbor were applied and compared to determine the best fitted model. Based on metallographic images, a first calibration of the model’s parameters has also been carried out. The resulting machine learning model allows the prediction of creep pore sizes in the grain boundary of Alloy 247 for any given temperature and stress.
Non-Linear Flutter Analysis of Labyrinth Seals
Authors: Corral Roque , Greco Michele , Matabuena Luis 
Published: November 2022

Abstract
A simple nonlinear model to describe labyrinth seal flutter has been developed to assess the aeromechanic stability of straight-through labyrinth seals subjected to large gap variations. The model solves the one-dimensional integral mass, momentum, and energy equations of the seal for a prescribed motion numerically until a periodic state is reached. The model accounts for the effect, previously neglected, of high clearance variations on the stability. The results show that when the vibration amplitudes are small, the work-per-cycle coincides with the prediction of the Corral and Vega model (2018, “Conceptual Flutter Analysis of Labyrinth Seals Using Analytical Models. Part I: Theoretical Background”, ASME J. Turbomach.140(10), pp. 121006) and Corral et al. (2021, “Higher-Order Conceptual Model for Seal Flutter”, ASME J. Turbomach. 143(7), pp.071006), but for large vibration amplitudes nonlinearities alter the stability limit. In realistic cases, when the discharge time of the seal is much longer than the vibration period, the nonlinear effects are significant and tend to increase the unstable range of operating conditions. Furthermore, seals supported either on the high-pressure or low-pressure sides, stable for small vibration amplitudes, can destabilise when the vibration amplitude increases. The linear stability, though close in many situations to the nonlinear threshold, is not conservative, and attention must be paid to nonlinear effects.
On the Effect of Frequency Separation, Mass Ratio, Solidity and Aerodynamic Resonances in Coupled Mode Flutter of a Linear Compressor Cascade
Authors: Schuff Matthias , Chenaux Virginie Anne 
Published: November 2022

Abstract
At a low mass ratio of structure to air, the work-per-cycle approach, or better known as the energy method, will lead to non-conservative results as aerodynamic coupling of modeshapes acts destabilizing. Using the p-k method to solve the aeroelastic stability equation, the effects of various structural aspects are investigated for a two-dimensional compressor cascade in subsonic and transonic flow conditions. The investigated key parameters are frequency separation, mass ratio and solidity.
Furthermore, the effect of a high frequency dependency of the aerodynamic forces is presented. Such phenomena can happen in case of aerodynamic or acoustic resonances. If the resonance peaks are close to the aeroelastic frequency, a discontinuous behavior of the frequency or damping solution can lead to a rapid destabilization of the system, once the aeroelastic frequency moves from one side to the other of the peak. In these regimes, it is crucial to have a high quality representation of the frequency-dependent generalized aerodynamic forces for an accurate prediction of the flutter onset.
Stability of a Rotor Partially-Filled With Fluid: Test Facility and Experimental Results
Authors: Kasprzyk Marie , Sentmanat John , Delgado Adolfo 
Published: November 2022

Abstract
Fluid trapped in a hollow, rotating component may lead to subsynchronous vibrations, resulting in high vibration amplitudes. This asynchronous response is observed around 0.55–0.9x after passing through the first critical frequency and affects large rotating equipment such as centrifuges, fluid-cooled gas turbines, and jet engines. A test rig is designed to evaluate this self-excited asynchronous vibration. The high-speed rig comprises of a flexibly-mounted rotor partially filled with fluid, with an overhung test chamber providing an unobstructed view of the liquid surface. A squeeze film damper provides external damping and allows operation through the asynchronous response when the test chamber contains a large amount of fluid. The results show the rotor response with different fluid depths and external damping values as the rotor-bearing system transverses the first critical speed (cylindrical mode). The experiments show that only a small amount of oil (∼20 mL) is required to induce asynchronous excitations, and increasing the fluid depth increases the amplitude of vibration. External damping slightly decreases the response, but it also expands the range of frequencies where asynchronous vibrations occur. At a given speed ratio, the vibrations reach a limit cycle, and subsequently, begin to drop as the rotor speed increases past the first critical speed.
Preliminary Numerical Validation of the Frequency Response Method on the Study of Aero-Damping in a Linear Oscillating Compressor Cascade
Authors: Tong Xin , Yin Fanfu , Shen Xin , Qiang Xiaoqing , Ouyang Hua 
Published: November 2022

Abstract
Preliminary numerical simulations are performed for validation of using the frequency response method on the study of aero-damping in a linear oscillating compressor cascade. The traveling wave method and influence coefficient method, based on the idea of the energy method, are also adopted for reference and comparison. The linearity of the unsteady pressure and the finite propagation of small flow disturbance is verified. The results of the aero-damping ratio obtained from different methods are in good agreement. Qualitative analysis is made on how the unsteady aerodynamic pressure distribution determines the overall aero-damping. When the frequency sweeps are conducted to measure aero-damping, the influence of aerodynamic stiffness cannot be ignored and the natural frequency offset caused by it should be taken into account. The existence of the two sidewalls in cascade has a certain impact on the measurement results, but it is still in an acceptable range. The application of the frequency response method on the study of aero-damping in the experiment is proved to be feasible and reliable in principle by numerical simulation.