bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressurized Thermal Shock Analysis With Sub-Modeling
Authors: Stefanini L. , Versteylen C. , Pangukir F. S. L. , Uitslag-Doolaard H. J. , de Haan - de Wilde F. H. E.
Published: October 2021

In 2020, the CFD analyses have been performed on a whole reactor vessel model. The action of accumulators during the PTS transient was considered. Using these data, an attempt to the efficient use of sub-modelling is carried out in order to obtain a strong reduction in the computational costs compared to a full 3D analysis. The analyses were given a probabilistic view by using the Master Curve approach for determining the material(s) fracture toughness.

In parallel with these activities, a literature review work was carried out at NRG. The single temperature dependence of the Master Curve was incorporated into characterizations of fracture toughness for all RPV steels of interest such as SA 508 Grade 3 and Grade 4N for both forging and weld material. The literature review helps to prove that the Master Curve approach models the temperature dependence of fracture toughness for a generic pressure vessel before and after irradiation. This is because all of these steels have a BCC matrix phase lattice structure. Based on ASTM E1921, the types of microstructure falling under a BBC matrix, such as bainite, tempered bainite, tempered martensite, ferrite and pearlite, could also be evaluated using the Master Curve model. Furthermore, it is found that the chemical composition is one of parameter to look for as driving force in embrittlement RPV due to irradiation. For the very high nickel steels examined (SA508 Grade 4N), when not combined with copper and moderate manganese, irradiation is not a serious embrittling agent.

This paper describes the work performed at NRG in the years 2017–2020 in investigting the Pressurized Thermal Shock (PTS) phenomenon, summarizes the achievements and gives a general judgement of the lessons learned. Moreover, this paper aims to illustrate the scope of planned research on PTS and its role in the new NRG research program PIONIER 2021–2024. An overview of NRG’s effort to align itself with the international community is given. Particular attention is given to the probabilistic problematic related to PTS. In order to better understand this problematic and improve the current state of knowledge NRG will create a PFM tool. The tool aims to use the best practices from existing PFM software to try to answer to questions requiring attention (e.g. thermal-hydraulic uncertainty). The experience accumulated during the previous activities will be included in the tool.
Exploring Life Extension Opportunities of High-Pressure Hydrogen Pressure Vessels at Refueling Stations
Authors: Ronevich Joseph A. , San Marchi Chris , Brooks Dusty , Emery John M. , Grimmer Peter , Chant Eileen , Sims J. Robert , Belokobylka Alex , Farese Dave , Felbaum John
Published: October 2021

High pressure Type 2 hoop-wrapped, thick-walled vessels are commonly used at hydrogen refueling stations. Vessels installed at stations circa 2010 are now reaching their design cycle limit and are being retired, which is the motivation for exploring life extension opportunities. The number of design cycles is based on a fatigue life calculation using a fracture mechanics assessment according to ASME Section VIII, Division 3, which assumes each cycle is the full pressure range identified in the User’s Design Specification for a given pressure vessel design; however, assessment of service data reveals that the actual pressure cycles are more conservative than the design specification. A case study was performed in which in-service pressure cycles were used to re-calculate the design cycles. It was found that less than 1% of the allowable crack extension was consumed when crack growth was assessed using in-service design pressures compared to the original design fatigue life from 2010. Additionally, design cycles were assessed on the 2010 era vessels based on design curves from the recently approved ASME Code Case 2938, which were based on fatigue crack growth rate relationships over a broader range of ΔK. Using the Code Case 2938 design curves yielded nearly 2.7 times greater design cycles compared to the 2010 vessel original design basis. The benefits of using in-service pressure cycles to assess the design life and the implications of using the design curves in Code Case 2938 are discussed in detail in this paper.
Fatigue Crack Growth Study of X70 Line Pipe Steel in Hydrogen Containing Natural Gas Blends
Authors: Chandra Ashwini , Thodla Ramgopal , Prewitt Thomas Joseph , Matthews Wendy , Sosa Siari
Published: October 2021

Blending hydrogen in the natural gas transmission and distribution systems is an option for hydrogen transportation. Integrity management of the existing infrastructure requires a risk evaluation for the planned hydrogen introduction and the challenge of hydrogen embrittlement needs to be considered. The aim of the current study was to evaluate the effect of blending different percentages of hydrogen in methane on the fatigue crack growth rate (FCGR) of X70 line pipe steel. Microstructures associated with base metal, weld center line (WCL) and heat affected zone (HAZ) of girth welds, as well as WCL and HAZ of SAWL seam weld were studied using compact tension specimens based on fracture mechanics. Hydrogen concentrations of 1, 5 and 10 mole% blended in methane were studied. The data was compared to baseline Paris curves in 100% methane as well as the BS7910 in-air mean curve for steel to quantify the increase in fatigue crack growth rate relative to inert environments. In addition, the data was also compared to the ASME B31 curve for carbon steel in hydrogen, to understand the degree of conservatism associated with the ASME curves for the concentrations of H2 evaluated. An increase in FCGR relative to methane baseline was observed for all the microstructures at all concentrations of hydrogen. However, the increase in FCGR relative to the in-air values varied with ΔK. Of the microstructures studied, the base metal showed the highest susceptibility to hydrogen embrittlement for all the hydrogen blends, followed by the girth weld – HAZ location. These two microstructures also had higher hardness compared to the other three locations. A crack growth assessment was also performed for circumferential and axial flaws utilizing the FCGR generated data coupled with pressure cycling data obtained from pipeline operations.
Development of Inhibitor for Corrosion Protection of Condensate Stripping Process in Industrial Coal Gasification Unit
Authors: He Meng , Kang Haoyuan , Liu Juanbo , Chen Sheng , Gong Xueru , Sun Li
Published: October 2021

The condensate involving HS-, CO32−, Cl− and NH4+ usually causes severe corrosion of 20 steel in condensate stripping process of industrial coal gasification unit. The corrosion can easily lead to failure of pipe fittings and vessels, and result in economic losses and personal injury. To protect industrial coal gasification unit against corrosion, five inhibitors including imidazoline, imidazoline amide, mannich base quaternary ammonium salt, pyridine, and sodium molybdate are investigated with experiment of linear polarization curve, polarization curve, electrochemical impedance spectroscopy (EIS). The gas-liquid two phase experimental conditions mixed with suitable concentration of H2S, CO2 and NH4Cl are as close to the industrial alkalescent corrosion environment as possible. The experiment results indicate that two inhibitors of the mannich base quaternary ammonium salt and the pyridine have better effects on corrosion protection than others at the same injection concentration of 100ppm. A new compound inhibitor is developed based on the mannich base quaternary ammonium salt and the pyridine in terms of above results. The new compound inhibitor’s efficiency further reaches to 95.5%, suggesting that the new compound inhibition has better effect on corrosion protection than either of two single inhibitors above.
Influence of Alcohol Additives on the Viscosity and Solubility of Ethanol/Diesel Fuel Blends: A Molecular Dynamics Simulation Study
Authors: Li Xueying , Hou Lei , Chai Chong , He Sichen
Published: October 2021

The viscosity and solubility of ethanol/diesel fuel blends have an important influence on its application in diesel engines. Molecular dynamics simulation was employed to study the effects of different alcohol additives on the viscosity and solubility of the blends between diesel and anhydrous ethanol. Among these alcohols, n-butanol, n-heptanol and n-decanol were selected for investigating the influence of alcohol chain length on solubility and viscosity. The results showed that the viscosity of the blends increased with the increasing of alcohol carbon number. The analysis of diffusion coefficient represented that the alcohol additives enhanced the molecular mobility and activity, and energy analysis indicated that alcohols with higher carbon numbers provided a better inter-soluble capacity. Taking these factors into account, n-heptanol can be recommended as a co-solvent additive for ethanol/diesel system due to the acceptable fuel properties and soluble performance.
The CFD Analysis of Erosion in the Four-Way Pipe of the Heavy Oil Thermal Production Wellhead
Authors: Wang Guotao , Zhang Chongchong , Duan Linlin , Sun Li , Liu Cenfan
Published: October 2021

In this work, the erosion in the four-way pipe of the heavy oil thermal production was studied by experiment and CFD simulations. The metallographic analysis and the micro erosion morphology of the damaged four-way pipe were done and analyzed. The erosion experiment of four-way pipe material ZG(J)35CrMo was carried out by the multiphase flow erosion tester, and the erosion prediction model was established and modified, which was coupled with the Euler-Largrangian gas-solid two phase flow model and used in the CFD simulations. First, the simulation results were compared with the actual invalidation case, through which the validity of the model is proved. Then, the effects of whether the pit defect located in the erodible site or not, fluid velocity, particle diameter and mass flow rate on the erosion rate were investigated using the CFD model. The erosion rate would increase with the fluid velocity, mass flow rate. And the results show that if the pit defect located in the erodible site coincidentally, the erosion rate will increase sharply, maybe several times, which may increase the failure risk of the four-way pipe increase.
Evaluation of Water Flow on Interfacial Strength in PSA Film Delamination
Authors: Inaba Kazuaki , Mashio Ibuki
Published: October 2021

To model the peeling phenomenon during cataract surgery and examine the effect of fluid flow during surgery, we constructed a simplified physical system and compared the case where only static pressure is applied to the adhesive thin film and the case where water flow is applied to the film by suction. From experiments with and without suctioning, the energy release rates of the adhesive thin film were calculated to be approximately 10 N/m, and no significant difference was confirmed with or without suction. We modeled the peeling phenomenon using the cohesive damage model and performed a finite element analysis considering the coupling of the fluid and membrane. The simulation results without suction were in good agreement with the theoretical values of the stress and deflection. When the water flow was applied to collide with the peeling part, the film deflection at the center became smaller, and the radial and circumferential stresses became smaller. From this result, it is shown that the stress acting on the membrane surrounding the crystalline lens can be reduced and peeling can be performed by successfully using the water flow for peeling.
Seismic Test and Seismic Response Analysis of U-Shaped Tubes With Square Array in Steam Generator
Authors: Monde Masatsugu , Ono Naoki , Mineno Tomonori , Hirota Kazuo
Published: October 2021

The heat transfer tubes of steam generators (SG) should not be damaged in an earthquake. The current seismic integrity assessment uses a simple model that integrates multiple pipes. In order to cover the increasing seismic loading conditions under Japanese regulations, more current and realistic estimates are needed than the conservative existing assessment methods.

In this study, all SG components, such as heat transfer tubes and anti-vibration bars (AVB), were modeled, and linear and nonlinear models were developed in order to evaluate more realistic responses and strains.

The natural frequency of the developed linear model and the strain distribution in the tube of the nonlinear model agreed well with the test results in the past. The effect of the AVB stiffness on the strain distribution of the tube has been evaluated by altering the thickness of the AVB.
Study on Method of Response under Turbulence Excitation of Steam Generator Heat Transfer Tube in Two-Phase Flow
Authors: Huang Xuan , Liu Shuai , Feng Zhipeng , Chen Guo , Wu Wanjun , Jiang Xiaozhou
Published: October 2021

The heat transfer tubes of steam generator (SG) are the pressure boundary of primary loop of Pressurized water reactor (PWR), and it is an important barrier to isolate radioactive material. The tubes are prone to fatigue, collision and wear caused by random turbulence excitation of two-phase flow. In the analysis of turbulence excitation, it is necessary to determine the random turbulence excitation based on the dimensionless reference equivalent power spectral density (EPSD), the flow parameters of the secondary side and the correlation length. In single-phase flow, the correlation length can be determined based on the tube gap and tube diameter. Two-phase flow contains two components, the correlation length of random turbulence in two-phase flow is more complicated, and few studies have been done. In this paper, an optimized analysis method on the response of SG heat transfer tube under random turbulence excitation is proposed by studying the EPSD and the correlation length in two-phase flow. Compared with the traditional spectrum analysis method, this method can consider many nonlinear factors such as clearance, collision and friction. Furthermore, the characteristics and mechanism of flow induced vibration of heat transfer tubes can be further clarified, and effective measure can be taken at the design stage of SG to effectively reduce the risk of excessive flow induced vibration.
The Elastic Characterization of Composite Based on Ultrasonic Waves
Authors: Park Y. H. , Dana J.
Published: October 2021

Anisotropic composite materials have been extensively utilized in mechanical, automotive, aerospace and other engineering areas due to high strength-to-weight ratio, superb corrosion resistance, and exceptional thermal performance. As the use of composite materials increases, determination of material properties, mechanical analysis and failure of the structure become important for the design of composite structure. In particular, the fatigue failure is important to ensure that structures can survive in harsh environmental conditions. Despite technical advances, fatigue failure and the monitoring and prediction of component life remain major problems. In general, cyclic loadings cause the accumulation of micro-damage in the structure and material properties degrade as the number of loading cycles increases. Repeated subfailure loading cycles cause eventual fatigue failure as the material strength and stiffness fall below the applied stress level. Hence, the stiffness degradation measurement can be a good indication for damage evaluation. The elastic characterization of composite material using mechanical testing, however, is complex, destructive, and not all the elastic constants can be determined. In this work, an in-situ method to non-destructively determine the elastic constants will be studied based on the time of flight measurement of ultrasonic waves. This method will be validated on an isotropic metal sheet and a transversely isotropic composite plate.
A Comprehensive Comparison Between Different Multiaxial Cycle Counting Procedure
Authors: Rovinelli Andrea , Messner Mark C. , Sham T.-L.
Published: October 2021

High-temperature nuclear design codes, such as Section III, Division 5 of the American ASME Boiler and Pressure Vessel Code and the French RCC-MRx, require evaluating fatigue damage for qualifying high-temperature components. Both codes provide clear guidance for counting cycles under uniaxial loading conditions, but neither provides a cycle counting procedure for multiaxial loading conditions. The ASTM E1049 also does not address multiaxial cycle counting. However, several widely utilized multiaxial cycle counting procedures are available in the open literature, but there is no agreement on the most appropriate method for high-temperature applications. Applying the different cycle counting methods to the same loading history generally produces different results. Comparisons between cycle counting procedures are available for low-temperature high-cycle fatigue but not for high-temperature low-cycle dwell-fatigue applications. This work presents an extensive comparison between different multiaxial cycle counting procedures potentially suitable for high-temperature low-cycle dwell-fatigue applications. Furthermore, how to conservatively assemble design transients to construct a loading history is also an open question. This work also investigates the uncertainty related to the loading sequence. The results guide the selection of the most appropriate cycle counting procedure, strain range metric, and cycle distribution for ASME Section III, Division 5 applications.
Evaluation of Load Reduction Effect Due to Through-Wall Crack in Surge Line Under Thermal Stratification Conditions
Authors: Kim Seung-Hyun , Park Hongsun , Kang Sun-Yeh , Kim Jong Min
Published: October 2021

The thermal stratification is a phenomenon in which layer is formed by density difference when high temperature fluid of pressurizer and low temperature fluid of hot leg nozzle are mixed in a surge line. A deflection and load of the surge line occurs due to thermal stratification. Therefore, the thermal stratification load is a major factor for the LBB (Leak-Before-Break) evaluation of surge line like the safe shutdown earthquake load. However, if a large amount of leakage occurs due to surge line break, the resulting load decreases because the crack itself and the plasticity around the crack region affect the load distribution of piping system. This load reduction effect is able to secure additional margin in LBB evaluation. The object of present study is to evaluate load reduction effect under thermal stratification due to the presence of a through-wall crack in surge line of nuclear power plant. Firstly, heat transfer analyses were performed under thermal stratification of surge line using FE (Finite Element) solid model. Secondly, the elastic-plastic analyses of FE model with a through-wall crack were performed by using the temperature distribution of surge line, and the reduced LBB loads due to the thermal stratification were derived. Finally, effect of load reduction and thermal stratification disappearance due to the leakage crack were evaluated and compared.
Vibration-Assisted Friction Stir Welding of AA 2024-T3 Plates
Authors: Sabry Ibrahim , Mourad Abdel-Hamid I. , Thekkuden Dinu Thomas
Published: October 2021

In this research, the weldability of AA 2024-T3 plates using vibration-assisted friction stir welding (VaFSW) is primarily inspected. The vibration imparted to the fixture holding the specimens in VaFSW differentiates this state-of-art process from the conventional friction stir welding (FSW) technique. For large-scale welding applications, it is ideal to vibrate the tool with the required amplitude and frequency for optimum performance. Due to limitation in applying vibration to the tool in a milling machine, the vibration is imparted to a custom-designed fixture and rig setup. The fixture, which holds the plates rigidly, is mechanically shaken during the friction stir welding process to boost the material strain in the weld region. The VaFSW is performed with 1800 rpm tool rotational speed, 16 mm/min travel speed and at four intermittent levels of vibrational frequencies (10.11 Hz, 13.56 Hz, 16.67 Hz, 25.17 Hz). The welding morphology and mechanical characteristics of joints produced using VaFSW and FSW are presented in the current work. Finally, the results of VaFSW are compared with conventional FSW. Results show that the tensile strength and, hardness in each of the zones — Nugget zone, heat affected zone, and base metal increased with the increase in the vibrational frequency in the vibration-assisted friction stir welding process. In addition, the ductility of the joints increased by the vibration in the vibration-assisted friction stir welding process due to excessive plasticized material resulting in a greater grain dislocation. Moreover, the mechanical characteristics of weld joints enhanced with the increase in the vibrational frequency. However, the tensile strength and hardness of conventional FSWed joint are slightly higher than the joint produced using VaFSW at 10.11 Hz. This study is promising for finding the capability of VaFSW over FSW to produce quality weld joints.
Review on the Current Progress of Thixoforming Process
Authors: Shitole Shubhra , Mourad Abdel-Hamid I.
Published: October 2021

Thixoforming is comparatively a recent semi-solid metal forming process that potentially uses the rheological behaviour of certain metals with non-dendritic microstructures. In contrast to the conventional forming process where the metals in either the solid or liquid state are subjected to a working load, the thixoforming uses a semi-solid slurry as feed material in which the non-dendritic solid particles are suspended in the liquid matrix. The thixoforming process is claimed to exhibit superior quality products by reducing the commonly observed defects such as shrinkage, porosity and macrosegration to a greater extent. As a result, many sectors have embraced the thixoforming technology such as the automotive industry for manyfacturing automotive comonet, piping systems and pistons without compromising on the efficiency. This review article focuses on the thixoforming processes for metal alloys, rheological, optimization of semi-solid slurry, potential applications, process parameters, heat treatment, advantages and disadvantages, and future scope.
Technical Basis for Increased Inspection Interval of Cold Leg Pressurized Water Reactor Dissimilar Metal Welds Using xLPR
Authors: Lohse Chris , Shim Do Jun , Dedhia Dilip , Dutta Rohan , Glunt Nathan
Published: October 2021

Alloy 82/182 Dissimilar Metal (DM) butt welds have been the subject of significant work due to their susceptibility to primary water stress corrosion cracking (PWSCC). The current rules for inspection of DM butt welds are contained in ASME Code Case N-770 (latest revision). These rules are based on crack growth rates that were originally published in MRP-115 in 2004. Since that time significant work has been performed to better understand the crack growth behavior of Alloy 82/182 materials in pressurized water reactors (PWRs) and updated crack growth rates have recently been published in MRP-420 (Rev. 1). These updated crack growth rates show a significant difference at lower temperatures which line up with the cold leg temperatures for PWRs (approx. 540–560°F). Additionally, the US Nuclear Regulatory Commission (NRC) working along with the Electric Power Research Institute (EPRI) recently released the xLPR computer code which is a probabilistic fracture mechanics code for evaluating DM butt welds. This paper evaluated various cold leg DM butt welds for PWRs using the xLPR probabilistic computer code to determine if a change in the frequency between inspections for unmitigated DM butt welds (Item B-1) from their current requirements in ASME Code Case N-770 is warranted. Failure probabilities were determined for the current technical basis using MRP-115 crack growth rates (with the current inspection duration) and compared to the probabilities using the new crack growth rates in MRP-420, Rev. 1 (with increased inspection durations). The evaluation results demonstrate that the duration between volumetric examinations for small and medium diameter DM butt welds from Code Case N-770, Inspection Item B-1, can be safely increased to once per 10-year ISI interval from the current requirement of once every 7 years when the specific requirements described in this paper are met.
Limit Loads of Bolted Flange Connections
Authors: Kirkemo Finn , Lutkiewicz Przemyslaw
Published: October 2021

High-pressure applications such as process piping, pressure vessels, risers, pipelines, and subsea production systems use bolted flange connections. Design of flanged joints may be done by design by rules and design by analysis. This paper presents a design by rules method applicable for flanges designed for face-to-face make-up. Limit loads are used to calculate the structural capacity (resistance) of the flanges, bolts, and metallic seal rings. Designers can use the calculation method to size bolted flange connections and calculate the structural capacity of existing bolted flange connections. Finite element analyses have been performed to verify the analytically based calculation method. The intention is to prepare for an ASME code case based on the calculation method presented in this paper.
Microstructural Based FEM-Calculation of Stress/Strain Fields in Steel AISI 316L and Its Validation by Digital Image Correlation
Authors: Niffenegger M. , Herrera Solaz V.
Published: October 2021

The prediction of damage mechanisms, such as fatigue in e.g. piping, requires the consideration of the microstructure because crack initiation starts at the grain level. Therefore, it is important to know the local strain/stress state, which due to the misorientation of neighboring grains, can reach significantly higher values than the nominal (macroscopic) ones. A finite element model for the calculation of stresses and strains as well as the formation of crack networks, based on the measured anisotropic microstructure of austenitic stainless steel, was developed at Paul Scherrer Institut (PSI). This mesoscale model (SNF) uses the sizes and crystallographic orientations of the grains, measured with 2- or 3-dimensional electron backscatter diffraction (EBSD) to generate a representative volume element (RVE) of the material. The anisotropic elastic properties and the anisotropic plastic behavior of each single crystal of the RVE, defined through the evolution of shear deformation in the slip plane with the highest Schmid factor, is considered. The corresponding single crystal properties have been preliminary determined by a standard tensile test followed by an inverse analysis procedure (Levenberg-Marquardt algorithm).

The SNF code uses a four-parameter damage model for crack initiation and growth and is based on the accumulated inelastic hysteresis energy. Besides the calculation of local stresses and strains in the microstructure, this model allows the calculation of high (HCF) and low cycle fatigue (LCF) lifetime and to perform sensitivity studies, e.g. to analyze the influence of grain sizes and orientation or multiaxial loading on the stress-strain curves.

The local strains in the microstructure, calculated by the SNF model, were validated by the crystal plasticity finite element (CPFEM) code CAPSUL and by measurements with a digital image correlation system (DIC). Good agreement between strains evaluated with these three different methods was observed up to nominal strains of about 4%. The analyses have shown that local strains can be up to a factor 2 higher than the applied global strain.

Furthermore, aspects such as the influence of 2D or 3D EBSD data and the approximation with corresponding columnar, synthetic or real grain geometries with finite elements (FE) on the accuracy of the calculated strains are also discussed.
Prediction of J-Integrals at Defects in W-9CR Steel Sandwich-Type Cooling Pipes
Authors: Calvet Tristan , Wang Yiqiang , Pham Minh-Son , Davies Catrin M.
Published: October 2021

Sandwich-type cooling pipes of the first wall of future fusion nuclear reactors (i.e. DEMO) will likely consist of tungsten brazed to a Reduced Activation Ferritic Martensitic (RAFM) steel. Under a high heat flux (HHF) (1–5 MW/m2) the mismatch in thermal expansion between tungsten and steel results in significant thermal stresses in the brazing region. These stresses can cause crack initiation and growth and thus compromise the structural integrity of such pipes. Finite element analyses have been performed on the brazed joints of a reference cooling assembly under HHF. Thermal stresses and resulting plastic strains were estimated for both the braze interlayer and parent materials. As images of brazed joints revealed, brazing processes are very likely to induce defects near the edges of the joints. A crack is therefore introduced in the brazed region where simulated stresses and strains are found to be the highest. J-integrals were calculated for cracks growing from an edge to the center of the considered piping assembly. The results are discussed in relation to the current sandwich-type piping design of the DEMO reactor.
Negative R Fatigue Short Crack Growth Rate Testing on Austenitic Stainless Steels
Authors: Griffiths Adam , Gill Peter , Coult Ben , Beswick Jack , Platts Norman , Mann Jonathan , Currie Chris , Airey Joe
Published: October 2021

The effect of an LWR environment on fatigue life is currently assessed using methods (such as NUREG/CR-6909) that may be excessively conservative when applied to plant components and loading transients. To reduce this conservatism, the ASME Working Group for Environmental Fatigue Evaluation Methods (WG-EFEM) has proposed the development of an improved assessment methodology for environmental fatigue based on a Total Life Prediction approach that would be adequately, but not excessively, conservative. Such an approach necessitates the development of analytical methods for the various stages of crack nucleation, short crack growth and long crack growth. Hence, there is a requirement to undertake testing within the short crack growth regime that would bridge the gap between fatigue nucleation and long crack growth (Paris Law) enabling better prediction of total life measured by fatigue endurance.

Previous negative R long crack growth testing using corner-crack specimens measured the effects of crack closure under compressive loading, and has been used to address some of the conservatism in existing assessment methods. This methodology has been developed further to enable negative R short crack growth testing with in-situ monitoring using DCPD. Testing has been undertaken in both high temperature air (300°C) and a simulated PWR primary water chemistry at 300°C on both cold-worked and non-cold-worked stainless steel specimens at a load ratio of R = −1. One heat of stainless steel has been tested, with another heat of different grain size to be tested imminently, in order to investigate the effect of grain size on short crack growth rates. FEA modelling has been undertaken to both correlate Direct Current Potential Drop (DCPD) response with crack growth measurements, and to determine the effective stress intensity factor ranges applied under the loading conditions based on the specific material properties.

This paper describes the methodology and findings from this negative R short crack growth test programme. Crack growth rates have been compared to ASME Code Sec. XI and Code Case N-809 reference curves and results from material specific in-house testing to assist the understanding of the behaviour of mechanically short cracks.
Prediction of Residual Stresses and Stress Intensity Factors in Fracture Mechanics Samples Manufactured by Laser Powder Bed Fusion
Authors: Fielden Michael , Davies Catrin M.
Published: October 2021

Laser Powder Bed Fusion (LPBF) is an effective form of additive manufacturing, but generates large residual stresses in the components which can be detrimental to their structural integrity and hence require quantification. Thermo-mechanical simulations of the build process of single edge notched fracture mechanics samples manufactured by LPBF from 316L stainless steel powder in horizontal & vertical orientation were developed in ABAQUS. The models examined the influence of crack introduction methods and specimen build orientation on crack tip stress distribution, to determine their potential effect on fatigue crack growth behavior. Contour plots of residual stresses show significant relaxation upon sample removal from the base plate in the horizontal samples due to the geometry of the component. Relaxation was observed in vertically orientated samples but to a much lesser extent and maximum principal stresses of around 400 MPa remained near the crack tip. It is concluded that residual stresses can be neglected in horizontally built samples of these dimensions, however residual stresses need careful consideration in vertically built samples.
Investigation of Highly Sensitive 3D-Printed Liquid Sensors Using Response Surface Methodology
Authors: Aliheidari Nahal , Ameli Amir
Published: October 2021

Traditional conductive polymer nanocomposite (CPN) liquid sensors have been studied for many years. However, they suffer from low sensitivity due to insufficient surface area and access points to the solvent. With increasing demand for highperformance smart sensors, the traditionally fabricated liquid sensors need major improvements in their performance. By introducing fused filament fabrication (FFF) smarter and environmentally friendlier parts can be made. The integration of FFF and CPN can provide increased degrees of freedom in the design and fabrication of liquid sensors.

In this work, design, 3D printing, and characterization of thermoplastic polyurethane/carbon nanotube (TPU/CNT) nanocomposites in response to acetone, toluene, and ethanol as solvents were conducted using a central composite design (CCD). CNT content, infill density, printing pattern, and solvent type were chosen as input factors and the sensor sensitivity was considered as the dependent response.

Response surface methodology (RSM) was employed to systematically assess the main effects and their quadratic terms and the two-way interactions of input parameters and identify the significant factors. The results showed that the solvent type, infill density, and CNT content are very significant factors while the infill pattern does not have a significant effect on the sensor sensitivity. The two-way interactions between the infill*solvent and CNT*solvent were found to have a P-value in the range of 0.05 and 0.1. A reduced model which offers a significant level of simplicity can be used to statistically describe the response behavior for further studying, design, and optimization of the sensors.
A Lumped Parameter Electro-Mechanical-Fluid Coupling Model for an Oscillating Beam in Fluids
Authors: Shan Xin , Bilgen Onur
Published: October 2021

A beam bonded with a Macro-Fiber Composite actuator can generate transverse deformations, enabling mechanism-free flapping wings and underwater oscillating fins. A piezocomposite beam can be actuated harmonically by a resistance-inductor-capacitor resonator, and interact with ambient fluid to yield flow vectoring, control, and/or propulsion. In this paper, an electro-mechanical-fluid coupled model is developed to obtain insight into the coupling mechanism, and provide guidance to investigate the system optimal parameters. To give prominence to the coupling mechanisms, the system is simplified to a lumped parameter model. The electromechanical coupling is modeled as a transformer, and the fluid-structure interaction is represented by the added mass and added damping effects, which are determined by solving linearized Navier-Stokes equations. The coupled model is converted into a transfer function, where the system input is voltage, and the output is displacement. A case study is conducted based on the coupled model, and important system properties are revealed.
Isolation and Characterization of Lignocellulose-Degrading
Geobacillus thermoleovorans
from Yellowstone National Park
Authors: Meslé Margaux M. , Mueller Rebecca C. , Peach Jesse , Eilers Brian , Tripet Brian P. , Bothner Brian , Copié Valérie , Peyton Brent M.
Published: October 2021

Since lignocellulosic biomass represents a major agro-industrial waste and renewable resource, its potential to replace nonrenewable petroleum-based products for energy production is considerable. Microbial ligninolytic and cellulolytic enzymes are of high interest in biorefineries for the valorization of lignocellulosic biomass, as they can withstand the extreme conditions (e.g., high temperature and high pH) required for processing.
Specificity of SARS-CoV-2 Antibody Detection Assays against S and N Proteins among Pre-COVID-19 Sera from Patients with Protozoan and Helminth Parasitic Infections
Authors: Yansouni Cedric P. , Papenburg Jesse , Cheng Matthew P. , Corsini Rachel , Caya Chelsea , Vasquez Camargo Fabio , Harrison Luke B. , Zaharatos Gerasimos , Büscher Philippe , Faye Babacar , Ndiaye Magatte , Matlashewski Greg , Ndao Momar
Published: October 2021

We aimed to assess the specificity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody detection assays among people with tissue-borne parasitic infections. We tested three SARS-CoV-2 antibody-detection assays (cPass SARS-CoV-2 neutralization antibody detection kit [cPass], Abbott SARS-CoV-2 IgG assay [Abbott Architect], and Standard Q COVID-19 IgM/IgG combo rapid diagnostic test [SD RDT IgM/SD RDT IgG]) among 559 pre-COVID-19 seropositive sera for several parasitic infections.
Selective Culture Medium for Screening of Fosfomycin Resistance in
Enterobacterales
Authors: Nordmann Patrice , Sadek Mustafa , Ortiz de la Rosa José Manuel , Pfister Stefan , Fournier Claudine , Poirel Laurent
Published: October 2021

A selective medium for screening fosfomycin (FOS)-resistant
Enterobacterales
was developed. Performances of this medium were first evaluated by using cultures of a collection of 84 enterobacterial clinical strains (42 FOS susceptible and 42 FOS resistant).
No plate tectonics necessary to explain Eoarchean rocks at Isua (Greenland)
Authors: Rollinson Hugh
Published: October 2021

Trace element and isotopic data for basalts from the Isua greenstone belt, West Greenland, indicate that they were derived from a range of mantle reservoirs that included depleted lower mantle, the mantle transition zone, and a primitive mantle reservoir probably located in the shallow upper mantle. Modeling of trace element compositions indicates that the Isua basalts were formed through the mixing between and refertilization of these diverse sources and their resultant melts and that this took place in the shallow upper mantle. It is proposed that the melting and mixing were driven by the heat transferred from hot deep mantle sources. This geochemical interpretation leads to a geodynamic model in which deep mantle domains rise to melt in the shallow mantle where there is mixing between a range of sources and melts. There is no evidence for material descending from the shallow to deeper mantle and no necessity for the involvement of crustal materials. These processes imply the activity of a mantle plume and/or heat pipe.
Formation of low-gradient bedrock chutes by dry rockfall on planetary surfaces
Authors: Sun Zhongheng , Ulizio Thomas P. , Fischer Jade N. , Levin Janette N. , Beer Alexander R. , Dickson James L. , Lamb Michael P.
Published: October 2021

Channel-like forms are ubiquitous on steep hillslopes on Earth, Mars, and other planetary bodies. On Earth and Mars, these landforms are commonly attributed to water activity, especially for slopes below the angle of repose (∼30°) where dry granular flows are considered ineffective. While the angle of repose characterizes loose sediment stability, it is unclear whether dry rockfall can traverse and erode channels in bedrock or cemented substrates. We used a large-scale experiment to show that bedrock chutes can form spontaneously at low gradients from dry rockfall. Our results, combined with observations of rocky outcrops and boulders on Mars, indicate that rockfall can be an important bedrock degradation process that can produce low-gradient channels in the absence of water.
Focused fluid-flow structures potentially caused by solitary porosity waves
Authors: Yarushina Viktoriya M. , Wang Lawrence Hongliang , Connolly David , Kocsis Gábor , Fæstø Ingrid , Polteau Stephane , Lakhlifi Assia
Published: October 2021

Gas chimneys, fluid-escape pipes, and diffused gas clouds are common geohazards above or below most petroleum reservoirs and in some CO2 storage sites. However, the processes driving the formation of such structures are poorly understood, as are the time scales associated with their growth or their role as long-term preferential fluid-migration pathways in sedimentary basins. We present results from a multidisciplinary study integrating advanced seismic processing techniques with high-resolution simulations of geological processes. Our analyses indicate that time-dependent rock (de)compaction yields ascending solitary porosity waves forming high-porosity and high-permeability vertical chimneys that will reach the surface. The size and location of chimneys depend on the reservoir topology and compaction length. Our simulation results suggest that chimneys in the studied area could have been formed and then lost their connection to the reservoir on a time scale of a few months.
A prolonged, two-step oxygenation of Earth's early atmosphere: Support from confidence intervals
Authors: Hodgskiss Malcolm S.W. , Sperling Erik A.
Published: October 2021

The Great Oxidation Event (GOE), among Earth's most transformative events, marked the sustained presence of oxygen above 10−5 times the present atmospheric level. Estimates of the onset of the GOE span 2501–2225 Ma and are based primarily on the loss of mass-independent fractionation of sulfur isotopes (MIF-S) in pyrite. To better constrain the timing of the GOE, we apply probabilistic techniques to estimate the confidence intervals of four proxies: MIF-S, redox-sensitive detrital minerals, “red beds,” and I/(Ca + Mg). These GOE proxies are drawn from a highly fragmentary geologic record, and consequently, estimates of the 95% confidence intervals span tens to hundreds of millions of years—orders of magnitude larger than suggested by radiometric constraints on individual successions. Confidence interval results suggest that red beds and nonzero I/(Ca + Mg) values may have appeared earlier than 2480 Ma and 2460 Ma, respectively, whereas redox-sensitive detrital minerals and MIF-S may have disappeared after 2210 Ma and 2190 Ma, respectively. These data suggest a delay of potentially >300 m.y. between initial and permanent oxygenation of the atmosphere and a delay of tens of millions of years between onset of the Lomagundi-Jatuli carbon isotope excursion and permanent oxygenation of the atmosphere.
Fully automated grading system for the evaluation of punctate epithelial erosions using deep neural networks
Authors: Qu Jing-Hao , Qin Xiao-Ran , Li Chen-Di , Peng Rong-Mei , Xiao Ge-Ge , Cheng Jian , Gu Shao-Feng , Wang Hai-Kun , Hong Jing
Published: October 2021

Purpose

The goal was to develop a fully automated grading system for the evaluation of punctate epithelial erosions (PEEs) using deep neural networks.

Methods

A fully automated system was developed to detect corneal position and grade staining severity given a corneal fluorescein staining image. The fully automated pipeline consists of the following three steps: a corneal segmentation model extracts corneal area; five image patches are cropped from the staining image based on the five subregions of extracted cornea; a staining grading model predicts a score for each image patch from 0 to 3, and automated grading score for the whole cornea is obtained from 0 to 15. Finally, the clinical grading scores annotated by three ophthalmologists were compared with automated grading scores.

Results

For corneal segmentation, the segmentation model achieved an intersection over union of 0.937. For punctate staining grading, the grading model achieved a classification accuracy of 76.5% and an area under the receiver operating characteristic curve of 0.940 (95% CI 0.932 to 0.949). For the fully automated pipeline, Pearson’s correlation coefficient between the clinical and automated grading scores was 0.908 (p<0.01). Bland-Altman analysis revealed 95% limits of agreement between the clinical and automated grading scores of between −4.125 and 3.720 (concordance correlation coefficient=0.904). The average time required for processing a single stained image during pipeline was 0.58 s.

Conclusion

A fully automated grading system was developed to evaluate PEEs. The grading results may serve as a reference for ophthalmologists in clinical trials and residency training procedures.
IQOS marketing strategies in the USA before and after US FDA modified risk tobacco product authorisation
Authors: Berg Carla J , Romm Katelyn F , Bar-Zeev Yael , Abroms Lorien C , Klinkhammer Katharina , Wysota Christina N , Khayat Amal , Broniatowski David A , Levine Hagai
Published: October 2021

Introduction

Given that the US Food and Drug Administration (FDA) authorised reduced exposure messaging to be used in IQOS marketing, we examined: (1) IQOS ad content; (2) advertising media channels and (3) changes in advertising efforts over time.

Methods

We conducted a mixed-methods study regarding IQOS ad content (headlines, themes, images), ad occurrence characteristics (including content, media channels and adspend) in the USA from August 2019 to April 2021 using Numerator advertising/marketing data.

Results

Across 24 unique ads and 591 occurrences (84.6% online, 8.0% print, 7.4% mobile), there was $4 902 110 total adspend (98.9% allocated to print). Across unique ads, occurrences and adspend, prominent themes included ‘real tobacco’ (45.8%, 47.4%, 30.1%, respectively), less odour/ash (29.2%, 21.0%, 29.9%) and switching from cigarettes (25.0%, 19.5%, 69.4%), and images mainly featured the product alone (58.2%, 61.4%, 99.5%) or with women (25.0%, 19.1%, 0.3%). Per occurrences and adspend, the most prominent media channel themes (eg, magazine/website topics) were technology (19.3%, 10.6%), women’s fashion (18.1%, 26.2%), weather/news (9.0%, 15.3%) and entertainment/pop culture/gaming (8.5%, 23.1%). Ad themes appearing only post-FDA authorisation included switching from traditional cigarettes, same-day/home-delivery, convenience (eg, use indoors), reduced exposure to some dangerous substances, science/research and distinction from e-cigarettes. Overall adspend per occurrence increased postauthorisation (p=0.016); the highest adspend per unique ad (69.3% of total) focused on ads featuring reduced exposure.

Conclusions

Regulatory efforts must be informed by ongoing surveillance of IQOS marketing efforts and its impacts, particularly how specific consumer subgroups (eg, tobacco non-users, women, young people) are impacted by marketing exposure.