bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defect Detection of Polyethylene Gas Pipeline Based on Convolutional Neural Networks and Image Processing
Authors: Wang Jun-qiang , Zha Sixi , Sun Jia-chen , Wang Yang , Lan Hui-qing 
Published: September 2024

Abstract
In this paper, a method based on image recognition was proposed to detect the defects of polyethylene (PE) gas pipeline, especially the deformation due to the indentation. First, the pipeline -detection VGG (PD-VGG) model was established based on the convolutional neural network (CNN), and appropriate model parameters were optimized through model training. The defect recognition rate of the improved model can reach 94.76%. Following, the weighted average graying algorithm was used to separate the defects characterized by deformation. Then, an improved gamma correction algorithm was applied to achieve image enhancement, and the interference of impurities adhered on intersurface of pipeline was also removed by using multilayer filters. The edge detection of the defect image was completed by using the Canny operator, and following the screening between the target contour and the interference contour by using top-contour. Finally, the algorithm for minimum outer rectangle algorithm was used to fit the defect contour, and the eigenvalues of deformation defects were extracted. The results indicate that the above defect detection method can better extract the deformation contour of the dented pipeline. The high agreement with the experimental results provides a basis for the research of effectively recognizing whether the pipeline has undergone ductile failure only through profile detection of defects.
Thermal Striping Limits Analysis on the Cylinder With a Defect of Liquid-Cooled Nuclear Fast Reactors
Authors: Yu Mingda , Du Juan , Shao Xuejiao , Pu Zhuo 
Published: September 2024

Abstract
The structural safety of the cylinder in liquid-cooled fast reactors is significantly affected by high-temperature thermal striping on the cylinder wall due to the free level fluctuation. Based on the elevated-temperature creep-fatigue evaluation theory of the RCC-MRx rules, combined with the finite element and numerical heat transfer analysis methods, a thermal analysis method appropriate for the fast reactor cylinder containing hypothetical cracks after being subjected to normal transient loads was established. The proposed model is validated compared with the test reactors, FAENA and SUPERSOMITE, and the calculated thermal striping limits agree with the experimental data. Furthermore, the involved model was implemented to predict the thermal striping limits for several ideal normal transients. Simultaneously, the effects of some key parameters, including the frequency, the heat transfer coefficient, wall thickness, and the mean temperature of the fluid on the thermal striping limit of the SS316 stainless steel cylinder were studied.
Design and Implementation of a Computer-Controlled Hybrid Oscillatory Ventilator
Authors: Cruz Andrea F. , Herrmann Jacob , Hajdarevic Bakir , Hawley Monica L. , Fox Donald , Bates Jason H. T. , Kaczka David W. 
Published: September 2024

Abstract
During mechanical ventilation, lung function and gas exchange in structurally heterogeneous lungs may be improved when volume oscillations at the airway opening are applied at multiple frequencies simultaneously, a technique referred to as multifrequency oscillatory ventilation (MFOV). This is in contrast to conventional high-frequency oscillatory ventilation (HFOV), for which oscillatory volumes are applied at a single frequency. In the present study, as a means of fully realizing the potential of MFOV, we designed and tested a computer-controlled hybrid oscillatory ventilator capable of generating the flows, tidal volumes, and airway pressures required for MFOV, HFOV, conventional mechanical ventilation (CMV), as well as oscillometric measurements of respiratory impedance. The device employs an iterative spectral feedback controller to generate a wide range of oscillatory waveforms. The performance of the device meets that of commercial mechanical ventilators in volume-controlled mode. Oscillatory modes of ventilation also meet design specifications in a mechanical test lung, over frequencies from 4 to 20 Hz and mean airway pressure from 5 to 30 cmH2O. In proof-of-concept experiments, the oscillatory ventilator maintained adequate gas exchange in a porcine model of acute lung injury, using combinations of conventional and oscillatory ventilation modalities. In summary, our novel device is capable of generating a wide range of conventional and oscillatory ventilation waveforms with potential to enhance gas exchange, while simultaneously providing less injurious ventilation.
Equivalent Circuits for Exergy Flow in Thermodynamic Systems
Authors: Kocher Jordan D. , Yee Shannon K. 
Published: September 2024

Abstract
The second law of thermodynamics explains the nature of all spontaneous processes, and it imposes a limit on the performance of all technologies, from heat engines to refrigerators. These limits are well described as early as Sadi Carnot's 1824 publication that established the field of thermodynamics; researchers later developed the concept of exergy, or the available work, that a thermodynamic system can produce when interacting with a specified environment. In this work, we describe a resistance analogy for thermodynamic systems, in which the need to remove entropy forces some amount of energy to leave the system as heat rejection. Specifically, it is the inverse temperature of the heat sink that resists energy flowing out of the system as heat rejection. An equivalent circuit can be drawn for any thermodynamic system, with energy flowing through different branches of the circuit. The different paths correspond to different energy and exergy flows, including the energy that must flow out of the system as heat rejection and, therefore, cannot contribute to the exergy content of the system. After establishing this equivalent circuit, it is applied to a natural gas combined cycle example problem, a desalination example problem, and a transient heating problem.
Fatigue Analysis of Nitinol Peripheral Artery Stents Under Complex Loads
Authors: Chen Yanlong , Feng Haiquan , Zhang Hailu , Su Juan , Wang Lin 
Published: September 2024

Abstract
The complex deformation of a peripheral arterial stent during limb movements is the main reason for its fatigue fracture. The aim of this study is to explore the impact of complex loads on the fatigue behavior and life of lower limb arterial stents. Specifically, the finite element simulation was adopted to compare and analyze the fatigue performance of three stents under five superimposed loads. Besides, the life and the fatigue crack growth life of these stents were predicted. It demonstrated that the bending load superimposed on other loads exerted a significant impact on the fatigue performance of these stents. The “spiral” structure design of the stent helped to improve the fatigue durability under complex deformations. Moreover, the prediction method for fatigue crack growth life is relatively conservative, which accounted for approximately 65–97% of the full life. The work provides important references for the fracture assessment and the optimization design of structure of stents.
A Comparative Evaluation of New and Used Dental Explorer Working Tips
Authors: Valeri Arthur S. , Cage Charlie E. , Donovan Terrence E. 
Published: September 2024

Abstract
The dental explorer medical device assists multiple functions, including marginal assessment. The working tip quality of this instrument has been previously established as a factor affecting operator judgment. However, little data exists to demonstrate the actual quality of working tips in clinical practice. The purpose of this study is to investigate and quantify if any real, measurable differences of the explorer working tip dimension exist among such instruments currently in service and compare to published medical device industry standards. Twenty new #23 dental explorer instruments from two manufacturers served as controls and sixty-three instruments in circulation at a dental school clinic were observed using light microscopy. The instruments were measured 50 micrometers from the terminus. A one-way analysis of variance (ANOVA) was performed to analyze values among groups. No statistically significant difference between the mean working tip dimension of new instruments was detected between brands. However, statistically significant differences between new and used instruments were detected regardless of brand. The range of values was 92.5–227.5 micrometers with average used instrument tip estimated over 50% wider than the average new instrument. These findings imply that other studies employing a dental explorer may be confounded if the instrument is not measured. Furthermore, the results of this study should serve as a motivating factor toward future research to update quality standards regarding the medical device with a goal of defining acceptable dimensions of the instrument working tip for certain applications in relation to clinical performance and expected outcomes.
Numerical Investigation of CO and NO Production From Premixed Hydrogen/Methane Fuel Blends
Authors: Singh Sanjana , Rajagopalan Haripriya , Emerson Benjamin , Noble David , Steele Robert , Lieuwen Tim C. 
Published: September 2024

Abstract
There is significant interest in utilizing hydrogen as an energy carrier in a net-zero carbon energy economy. A variety of fundamental and practical issues associated with premixed hydrogen/methane combustion must be addressed, particularly flame flashback, combustion instabilities, and NOx emissions. Significantly less attention has been given to CO emissions from hydrogen blending. However, recent H2 blending engine tests have clearly noted major reductions in CO emissions, reductions which substantially exceed what would be expected based upon C atom mass balances in the fuel. Moreover, NOx, CO, and combustor operability always tradeoff with each other, and so, for example, these CO reductions can also enable operational or design modifications to reduce NOx emissions and/or wider operability windows. This paper addresses H2 blending effects on CO emissions, addressing both the direct influences on CO emissions, as well as how it influences NOx–CO tradeoffs. The paper presents computations that differentiate between the kinetic and equilibrium effects of H2 blending, as well as how H2 blending can lead to reductions in both NOx and CO by moving the Pareto front downward. Finally, this work suggests that H2 blending, in addition to its CO2 reductions, can also increase plant operational flexibility and so provide additional value propositions to an evolving electricity market.
Performance Improvement of a Heat Sink for Battery Thermal Management System
Authors: Rasimarzabadi Faezeh , Azarkish Hassan , Crain Alexander , Recoskie Steven , Bordatchev Evgueni , Shirazy Mahmood 
Published: September 2024

Abstract
Dissipating heat generated by onboard battery systems is a key thermal management challenge for hybrid/electric aircraft. The National Research Council Canada is collaborating with Calogy Solutions, Ltd. (Sherbrooke, Quebec, Canada) to support their development of a novel aviation battery module. The goal of the project is to optimize the heat sink design for battery thermal management system by minimizing thermal resistance as well as reducing overall weight, considering fabrication cost to be used by the industry. In this research, the original heat sink used by Calogy (plate-fin type) was numerically simulated using commercial software and the results were compared with the experiment. This was done to validate the numerical simulation was accurate enough to be used for future simulations. The heat transfer of the heat sink was enhanced by optimizing fin dimensions and spacing, and fin design modification (a first in this application), based on system analysis of a kW scale hybrid/electric aircraft. The selected model as the optimized heat sink resulted in about 34% improvement in heat transfer coefficient, and about 24% reduction in weight comparing with the original plate-fin type heat sink.
Investigation of an Ammonia-Fueled SOFC-mGT Hybrid System: Performances Analysis and Comparison With Natural Gas-Based System
Authors: Anfosso Chiara , Crosa Silvia , Iester Federico , Bellotti Daria , Magistri Loredana 
Published: September 2024

Abstract
Hybrid systems (HS) are highly attractive in power generation due to their potential for higher power outputs and efficiencies by integrating different technologies. Among solid oxide fuel cell (SOFC) plants, the SOFC-Micro-Gas Turbine (mGT) system is particularly innovative. In this setup, the SOFC replaces the mGT combustion chamber, with an afterburner completing fuel combustion before the expander. Various configurations and control systems have been explored over the years, and prototypes have demonstrated satisfactory efficiency. However, these systems have predominantly used NG and Biogas, which do not achieve zero carbon emissions. The growing global demand for carbon-free energy production is increasing, highlighting the importance of alternative fuels in the power generation sector: among them, thanks to its chemical and physical properties, ammonia is gaining more and more interest. This work investigates an innovative ammonia-to-power system based on an SOFC-mGT HS, focusing on thermodynamic parameters, system features, and technical and environmental challenges. A MATLAB/Simulink model, built on a validated HS model fueled by NG, was developed to analyze the new system configuration. This configuration replaces the SOFC prereformer with an ammonia cracker, allowing for the exploration of anode gas recirculation effects and optimal system design. Key operating parameters such as anodic recirculation factor, fuel utilization, performance, and gas turbine characteristics are discussed. Finally, a comparison is made between hybrid systems and mGTs powered by methane, biogas, and ammonia.
Thermal Load Control in High-Temperature Heat Pumps: A Comparative Study
Authors: Pettinari Matteo , Frate Guido Francesco , Ferrari Lorenzo , Yücel Fatma Cansu , Tran A. Phong , Stathopoulos Panagiotis , Kyprianidis Konstantinos 
Published: September 2024

Abstract
High-temperature heat pumps (HTHPs) are becoming increasingly relevant in the industry as they represent a promising solution for decarbonizing industrial heat. These technologies can enable the electrification of industrial processes by exploiting electricity from renewables to provide process heat at temperatures above 250 °C, as in the case of emerging Brayton-based HTHPs. To succeed in this purpose, HTHPs must also ensure operational flexibility, which entails the ability to operate safely under varying loads and promptly respond to fluctuations in demand, while maintaining high efficiencies. Moreover, the ability to provide large flexible electric loads to transmission system operators has the potential to unlock innovative business cases and further promote the use of these systems. Common control strategies for achieving this include employing bypass mechanisms, fluid inventory control, and adjusting turbomachinery rotational speeds. Despite their variety, the simultaneous use of such control strategies is often limited as they may lead to significantly different system behaviors, both in terms of transient and steady performance. In this paper, rotational speed and fluid inventory control are examined from a transient perspective to maintain the desired sink temperature while regulating the thermal load of a novel Brayton-based HTHP. A comprehensive dynamic model of the system is proposed and leveraged to numerically test the two control approaches, aiming to provide insights for forthcoming experimental investigation. Results indicate that rotational speed control leads to negligible sink temperature residuals, while fluid inventory control better preserves the HTHP performances for varying temperature glides.
Assessment of the Wilshire-Cano-Stewart Model Using Strain Energy Density Dissipation
Authors: Pellicotte Jacob , Hossain Md Abir , Cano Jaime , Stewart Calvin M. 
Published: September 2024

Abstract
In this study, strain energy density (SED) is employed as a creep damage parameter to calibrate the Wilshire-Cano-Stewart (WCS) model. The WCS model is an adaptation of the Wilshire equations combined with continuum damage mechanics to enable predictions of creep deformation and damage. In WCS, the analytical calibration methods for the Wilshire equations remain unchanged and the additional damage parameters are found using numerical optimization. Though the WCS model can accurately predict progressive creep deformation, the damage remains phenomenological. Herein, damage is represented as SED. In SED, it is assumed that a material system has a finite amount of energy per unit volume that can be dissipated before failure. Assuming that SED is caused by the accumulation of microstructural defects, the damage process is represented as a scalar value from zero (undamaged) to unity (rupture). By combining the WCS model with SED, damage evolution is pinned physically and can be measured experimentally. Stress rupture, minimum-creep-strain-rate, and creep deformation data are gathered for alloy P91 at 600 °C and stresses from 100 to 200 MPa. The Wilshire constants are analytically determined and compared with the literature. The damage-trajectory constant is calibrated using SED measurements. The new calibration accurately predicts the material response across the range of stresses and temperatures. A comparison between numerical optimization and measured damage-trajectory constants is performed. Parametric simulations verify the interpolation and extrapolation capabilities of this new approach.
Vaneless Diffuser Modeling for Real Gas Supercritical Carbon Dioxide Flows: Need for a Data-Driven Approach
Authors: Seshadri Lakshminarayanan , Kumar Pramod 
Published: September 2024

Abstract
In this work, a real gas-based vaneless diffuser (VLD) differential equation model is presented. The model requires the specification of the skin friction coefficient as input. However, the use of standard VLD friction coefficient estimation expressions require a reexamination for supercritical CO2 (sCO2) flows. To establish the skin friction coefficient for real gas sCO2 flows, computational fluid dynamics (CFD) data are generated using Latin hypercube sampling (LHS), with boundary conditions spanning the typical operating conditions of sCO2 centrifugal compressors in the kW to MW scale of power generation. The CFD computations are carried out using ansys® cfx. The corresponding VLD friction coefficient for which the VLD stagnation pressure loss predicted by the one-dimensional (1D) differential equation model matches with the three-dimensional (3D) CFD result is back calculated for the LHS designs. This is carried out using a root finding function in MATLAB® software. The existing empirical relation that characterizes the VLD skin friction coefficient using the inlet Reynolds number alone shows a poor correlation (R2 = 0.26), when compared to the CFD data. It is evident that a data driven approach is required to model the sCO2 VLD real gas flow for accurate results. Using the LHS data, the efficacy of an artificial neural network (ANN)-based model is demonstrated. A two hidden layer ANN is developed, which accurately predicts the skin friction coefficient for sCO2 real gas flows (R2 = 0.87). This proposed ANN-based VLD model can be easily integrated into existing 1D codes for real gas sCO2 centrifugal compressor rating and sizing.
Modeling of Casing Containment in an Overspeeding Turbine Stage
Authors: Eryilmaz Ibrahim 
Published: September 2024

Abstract
This paper is on the structural characterization of a turbine casing in terms of blade containment. Gas turbines experience unintentional blade loss events in service for various reasons such as fatigue and the engines are certified on the basis that these events do not cause hazardous outcomes. In certain conditions, such as permanent loss of load after a shaft or transmission failure, the turbine stage(s) may accelerate to excessively high speeds creating the possibility of disk burst. An ls-dyna explicit finite element model of a bullet to plate experiment has been prepared with flat nose projectiles. Following the method verification, the procedure was applied for a turbine stage with a single layer and a multilayer casing to assess the performance of those in a blade-off at overspeed conditions when turbine experiences permanent loss of load. The intention with the multilayer casing is to allow penetration within the first layer to dissipate the energy of the fragments and to contain them within the second layer.
Rotordynamics of a Single-Stage Brush Seal in Isolation: The Effects of Variable Stiffness and Back Plate Geometry
Authors: Bird Joshua , Keogh Patrick S. , Sangan Carl M. , Bowsher Aaron A. , Crudgington Peter F. , Scobie James A. 
Published: September 2024

Abstract
Brush seals control leakage around rotating components from areas of high to low pressure inside turbomachinery. They are known to contribute to the overall stability of gas turbines, therefore their dynamic behavior is of particular importance to engine designers. Despite this, limited research exists in the literature on the rotordynamic behavior of brush seals. This paper aims to experimentally characterize the leakage and rotordynamic performance of two seals with different bristle diameters tested with both conventional and pressure-relieved back plates with a slight interference. A dynamic test facility was utilized to study the dynamic characteristics of an isolated seal with changes in excitation frequency, rotational speed, and pressure drop. Seal leakage increased with bristle diameter and with the use of the pressure-relieved back plate but reduced with increasing rotational speed for all tests. The direct dynamic coefficients were shown to increase with pressure difference. The back plate geometry influenced the change in stiffness coefficient with rotational speed. The larger bristle diameter resulted in a stiffer seal, however, the damping coefficient reduced with the reduction in packing density. The insight provided by these results will help inform engine manufacturers on the suitability of implementing brush seals in future gas turbine designs.