bluuebunny/crossref_metadata_2025_split huggingface dataset:
Safety Justification Strategy for the Implementation of Additive Manufacture Small-Bore Globe Valves for Nuclear Plant
Authors: Press Bill , Dukes Adam , Poole Dave , Adams Jack , Burling Luke , Sulley John 
Published: October 2021

Abstract
The Additive Manufacture (AM) of nuclear plant components, such as small-bore globe valves, offers opportunities to reduce costs and improve production lead-times. Cost reductions can be achieved by reducing raw material quantities, removing machining operations, and eliminating the welding of sub-assemblies. Furthermore, there is the opportunity to reduce production lead-times by simplifying the supply chain, e.g. reducing the number of parts to be sourced and eliminating special operations. Such opportunities are important against a backdrop of industry striving to reduce the cost of nuclear power generation in order to ensure viability with other forms of power generation.
However, AM is a relatively new and innovative manufacturing technology, and although now seeing greater use in industry, there are still very few examples of where the technology has been applied to components used in safety critical applications. Furthermore, it is not covered by the American Society of Mechanical Engineers (ASME), Section III, nuclear design code. For nuclear plant applications, it is imperative a robust safety justification is provided.
This paper presents Rolls-Royce’s approach to provision of a high integrity safety justification to enable the implementation of AM small-bore globe valves, up to a nominal bore size of 2” to nuclear plant. The material of construction is AM Laser Powder Bed Fusion (LPBF) 316LN stainless steel, with a Hot Isostatic Press (HIP) bonded LPBF Tristelle 5183 low cobalt hard facing seat.
The paper describes the structure of the safety justification, which follows a multi-legged approach. It provides an overview of the innovative manufacturing process, which is, to the best of Rolls-Royce’s knowledge, the first of a kind application on nuclear pressure boundary components.
The paper provides a summary of the suite of materials testing and metallurgical examinations conducted, and majors on prototype functional and performance testing where comparisons are made with the previous forged form. Pressure testing is covered which includes ultimate pressure testing to 2,000 bar, as well as: functional cyclic testing, hard facing bond strength tests, dynamic loading (shock), and cyclic thermal tests. In all cases the additive manufactured small-bore globe valves performed as well, and in some cases better than the forged material equivalent.
Reliability of Ultrasonic Testing at Crack Fields in Large Forgings
Authors: Juengert Anne , Jacobs Oliver , Gauder Patrick , Weihe Stefan 
Published: October 2021

Abstract
There is a possibility that crack fields form in large forgings, if the chemical composition and the manufacturing conditions interact in an unfavorable way and lead to hydrogen flaking. Comparable crack fields were found for example during ultrasonic inspections in reactor pressure vessels of two Belgian nuclear power plants in 2012. In an ongoing research project, new approaches for the assessment of crack fields are developed. The investigation of the reliability of ultrasonic testing techniques for crack fields is also a part of this project. Ultrasonic testing (UT) took place at a test block containing a crack field. The test block was later cut into plates and test specimen for destructive material tests were manufactured. In addition to the ultrasonic testing, magnetic particle testing (MT) was applied at the cutting surfaces of the plates and radiographic testing (RT) was done at the plates. The sum of all nondestructive examinations lead to a data set, that is in general suitable for the calculation of probability of detection curves (PoD). MT and RT deliver crack locations and crack sizes that are compared to the UT results.
With the results, PoD curves are calculated for UT testing at the crack field. Due to shadowing and material damping, the PoD curves should become poorer for areas deeper in the crack field. The paper shows the results from a PoD calculation using a Hit/Miss-Analysis from experimental data. The limits of the technique are discussed as well. Additionally, the interaction for the detected flaws will be investigated as far as possible according to actual codes.
ASME Post Construction Standards: 25 Years of Progress
Authors: Rodery Clay D. 
Published: October 2021

Abstract
The ASME Post Construction Standards Committee was formed in 1995 in response to an identified need for recognized and generally accepted engineering practices for the inspection and maintenance of pressure equipment after it has been placed in service. In 2020, the Committee marked its 25th year since its inception. This paper provides an overview of the history of that journey. It begins with a review of how post construction activities were addressed in the past, and how requirements for inspection, maintenance and repair of pressure equipment were addressed up until the early 1990s. It then chronicles the ASME activities from the formation of an ad-hoc task group through the formation of the committee, the identification of areas where standards were needed, and the publication of post construction standards within its scope. The paper also provides an overview of the post construction standards the committee has published, as well as other related documents and workshop activities.
The paper concludes with a look into the future, including strengths, weaknesses, opportunities, and threats. It is hoped that this paper offers unique insights into the history of post construction standards for pressure equipment and provides a case for continued involvement by interested volunteers to further develop and advance the mission of the committee.
Hydrogen Damage in Transfer Line Exchanger Tubes
Authors: Adams Amy , Huff Mary Catherine , Penso Jorge 
Published: October 2021

Abstract
This paper presents the analysis of a Transfer Line Exchanger (TLE) tube, which ruptured from hydrogen damage on the steam side. Hydrogen damage occurs where corrosion reactions result in the production of atomic hydrogen. Atomic hydrogen combines at grain boundaries or inclusions in the steel to produce molecular hydrogen. Hydrogen may also react with iron carbides (Fe3C) in the metal to produce methane (CH4). As a result, intergranular microfissures will form, linking to form larger microcracks and leading to eventual through-wall failure. Decarburization might also occur near the tube surface.
TLEs are heat exchangers designed to operate at extreme temperatures. In the exchanger design included in this study, pyrolysis furnace effluent gases enter the inner tubes at over 1500°F (815°C). The heat is then removed by water, which is supplied to concentric outer tubes, to generate steam. It is common for water-side damage in TLEs to occur at the tubesheet, where solids from boiler water are known to deposit and inhibit heat transfer. The nature of the rupture under discussion in this paper differs, because the location of the rupture was not near the tubesheet. Metallurgical analysis confirmed indications that the tube failure is attributed to hydrogen damage.
Effect of Internal Hydrogen on Fatigue Crack Initiation Sites in 316L Austenitic Stainless Steel
Authors: Kagay B. , Ronevich J. , San Marchi C. 
Published: October 2021

Abstract
Internal hydrogen can influence the fatigue life, crack growth rate, and crack morphology of austenitic stainless steel, but little is known about the effect of internal hydrogen on fatigue crack initiation sites. To determine the effect of internal hydrogen on the microstructural fatigue crack initiation sites, the location of small fatigue cracks was evaluated with respect to the microstructural features in notched middle tension M(T) 316L specimens both with and without pre-charged hydrogen. The notches of the M(T) specimens were electropolished prior to fatigue testing to facilitate post-test analysis. Fatigue tests were performed with the same constant load amplitude and an R-ratio of 0.1 for specimens with and without internal hydrogen. The fatigue tests were interrupted after a minimal amount of cracking was detected using the direct current potential difference (DCPD) technique. The microstructural locations of the small fatigue cracks were then evaluated with scanning electron microscopy imaging and electron backscatter diffraction (EBSD). Several small transgranular fatigue cracks initiated in the notches of specimens both with and without internal hydrogen. These transgranular cracks always intersected grain boundaries, twin boundaries, and/or triple points indicating that these microstructural features are the critical locations for crack initiation. The transgranular cracks did not propagate along the prominent slip traces. There was no discernible effect of hydrogen on the microstructural sites of fatigue crack initiation in 316L.
Thermal Analysis of a 9977 Shipping Package During a Fire-Drop-Smoldering Accident
Authors: Tamburello David , Kesterson Matthew , Escobar Andrew 
Published: October 2021

Abstract
The US Department of Energy (DOE) uses the 9977 shipping package to store and transport plutonium bearing materials. The shipping package utilizes a single 6-inch diameter containment vessel with the radioactive material within SAVY-4000 containers, 3013 food-pack containers, or other sealed storage containers separated by spacers. The 6-inch containment vessel is surrounded by load distribution fixtures and a foam insulation overpack to protect against fire and impact events. A facility fire-drop-smoldering accident, which is longer and hotter than the comparable regulatory transportation evaluation, is analyzed to ensure radioactive material containment is maintained. A sensitivity analysis of shipping package configuration and foam insulation reduction is considered with foam eliminated either along the inside wall of the drum body (Inner Foam) or eliminated from the outer walls of the inner chamber where the 6-inch containment vessel is located (Outer Foam). These two different foam reduction configurations were considered to conservatively simulate the potential aging effects on facility safety qualification during storage. In addition, the thermal properties of the foam insulation were varied to explore their potential aging effects. A minimum foam thickness needed to maintain containment during the hypothetical facility fire-drop-smoldering analysis is determined for both the Inner and Outer Foam configurations as well as for both the SAVY-4000 and 3013 food-pack container configurations.
Stress Relaxation Cracking of Thick-Wall Stainless Steel Piping in Various Refining Units
Authors: Penso Jorge , Shargay Cathleen 
Published: October 2021

Abstract
Hydrogen Manufacturing Units which have a Pre-reformer often use large diameter, thick-wall austenitic stainless steel (SS) piping operating at 540–650°C (1000–1200°F). In numerous units, circumferential welds in this piping have experienced failures due to stress relaxation cracking (SRC). Similarly, SRC has been reported in SS piping operating in this temperature range in hydroprocessing, olefin and coking units and in steam superheater coils in various units. This paper describes the in-service SRC mechanism and reports on some cracking case histories. It will also define how the risk varies depending on the process conditions, pipe size and thickness, fabrication steps and more. Additionally, this paper briefly lists the pros and cons of different material choices for this piping based on operating conditions, and ranks the materials for SRC resistance. Various other damage mechanisms also need to be considered and affect the optimum materials choice. The paper recommends steps for minimizing the risk of SRC of SS piping when SS is determined to be the preferred material choice. One of the key steps for providing resistance to in-service SRC is postweld heat treatment of the welds, but this has led to cases of reheat cracking during the fabrication stage. Guidelines for predicting and minimizing this risk are also reported.
Rotational Modular Metastructures for Cobot Impact Energy Absorption
Authors: Agarwal Vipin , Kidambi Narayanan , Wang K. W. 
Published: October 2021

Abstract
Collaborative robots (Cobots) are designed to allow humans to interact and work with them in close proximity. Although they are power- and force-limited compared to traditional industrial robots, residual injury risks in the event of a collision will cause Cobots to be operated at a reduced speed when humans are nearby. This compromises the ability to achieve manufacturing cycle time targets. Outlining safe zones around Cobots may allow quicker operations, but this approach poses challenges to manufacturing efficiency and leads to an increased robot footprint over a true collaborative unit. Incorporating energy-absorbing and force-limiting hardware into the Cobot structure may offer a way to ensure human safety without reducing manufacturing productivity and efficiency. Building upon such a concept, this research proposes a rotational multistable metastructure that can be incorporated in a Cobot’s joint. The metastructure consists of pre-buckled bistable beams constrained within a pair of concentric rings. These bistable elements snap through and absorb energy in consequence of applied rotational loads. In this study, modeling and analyses are performed using Euler’s elastica theory and results are used to guide the design of the metastructure, offering insight into properties such as rotation range, asymmetric bistability, and strain energy absorption. Using the geometric parameters obtained from the elastica study, numerical studies are conducted, and a modular constituent is fabricated and evaluated experimentally. While motivated by Cobot applications, it is expected that this work will serve as an important basis for a variety of engineering applications requiring energy absorption and force limitation for rotational loads.
An Experimental and Numerical Study of a Solid-State Ornithopter Wing Performance
Authors: Katibeh Mohammad , Bilgen Onur 
Published: October 2021

Abstract
Various concepts have been introduced in the literature to recreate avian wings’ flapping motion since natural flight has advantages for certain flight regimes, such as more maneuverability, efficiency, and agility, over fixed-wing aircraft. Similarly, the so-called solid-state ornithopter is designed to achieve a flapping wing motion; however, also achieves to use the minimum number of components. It utilizes an active layer of piezoelectric actuators over a composite substrate, and the flapping motion is generated through the induced strain from the piezoelectric actuators. Previously, a simplified rectangular plate-like design was studied for the variations of important geometric parameters. In this paper, more complicated and realistic geometries are investigated. The flapping performance is studied using a structural finite element model represented by parameters related to the wing’s motion such as tip displacement, bending curvature, and lateral slope. Furthermore, a set of experiments are conducted to verify the simulation results. During the experiments, the wing’s three-dimensional motion is recorded via a camera based motion-capture system. After that, the acquired data are processed using mathematical models to obtain the displacements, and parameters related to curvature, twist, and slope.
Evaluating the utility of digital phenotyping to predict health outcomes in schizophrenia: protocol for the HOPE-S observational study
Authors: Abdul Rashid Nur Amirah , Martanto Wijaya , Yang Zixu , Wang Xuancong , Heaukulani Creighton , Vouk Nikola , Buddhika Thisum , Wei Yuan , Verma Swapna , Tang Charmaine , Morris Robert J T , Lee Jimmy 
Published: October 2021

IntroductionThe course of schizophrenia illness is characterised by recurrent relapses which are associated with adverse clinical outcomes such as treatment-resistance, functional and cognitive decline. Early identification is essential and relapse prevention remains a primary treatment goal for long-term management of schizophrenia. With the ubiquity of devices such as smartphones, objective digital biomarkers can be harnessed and may offer alternative means for symptom monitoring and relapse prediction. The acceptability of digital sensors (smartphone and wrist-wearable device) and the association between the captured digital data with clinical and health outcomes in individuals with schizophrenia will be examined.Methods and analysisIn this study, we aim to recruit 100 individuals with schizophrenia spectrum disorders who are recently discharged from the Institute of Mental Health (IMH), Singapore. Participants are followed up for 6 months, where digital, clinical, cognitive and functioning data are collected while health utilisation data are obtained at the 6 month and 1 year timepoint from study enrolment. Associations between digital, clinical and health outcomes data will be examined. A data-driven machine learning approach will be used to develop prediction algorithms to detect clinically significant outcomes. Study findings will inform the design, data collection procedures and protocol of future interventional randomised controlled trial, testing the effectiveness of digital phenotyping in clinical management of individuals with schizophrenia spectrum disorders.Ethics and disseminationEthics approval has been granted by the National Healthcare Group (NHG) Domain Specific Review Board (DSRB Reference no.: 2019/00720). The results will be published in peer-reviewed journals and presented at conferences.Trial registration numberNCT04230590.
Association between mental health trajectories and somatic symptoms
following a second lockdown in Israel: a longitudinal study
Authors: Ben-Ezra Menachem , Hamama-Raz Yaira , Goodwin Robin , Leshem Elazar , Levin Yafit 
Published: October 2021

Objectives
To identify mental health prospective trajectories before and after
a second lockdown during the COVID-19 pandemic and their associations
with somatic symptoms.

Design
Prospective Study.

Setting
Population-based study drawn from a probability-based internet panel
of over 100 000 Israelis.

Participants
Adults aged 18 years or more, representative of the adult Israeli
population. The participants were measured at two time points (time 1
(T1) pre-second lockdown N=1029; response rate=76.17%; time 2 (T2)
post-second lockdown N=764; response rate=74.24%).

Main outcome measures
Trajectories of anxiety and adjustment disorder based on clinical
cut-off score for probable diagnoses across T1-T2, somatic symptoms at
T2. The four trajectories: stable-low, (no probable diagnosis),
stable-high (stable probable diagnosis), exacerbation (no probable
diagnosis at T1, probable diagnosis at T2), recovery (probable diagnosis
at T1, no probable diagnosis at T2).

Results
Three anxiety trajectories predicted probable somatic symptoms
(stable-high OR=6.451; exacerbation OR=5.379; recovery OR=2.025)
compared with the stable-low trajectory. The three adjustment disorder
trajectories also predicted somatic symptoms (stable-high OR=4.726;
exacerbation OR=6.419; recovery OR=4.666) compared with the stable-low
trajectory.

Conclusions
Our data show elevated somatic symptoms among those whose mental
health trajectories were poor, exacerbated and those who recovered
following the second lockdown. The presentation of somatic symptoms may
mask psychological vulnerabilities, even among those who appear to have
recovered from the stressor. This indicates that lockdown may be a
double-edged sword and should be carefully administered given these
populations vulnerabilities.
Community health workers’ job satisfaction in Ebola-stricken areas of Sierra Leone and its implication for COVID-19 containment: a cross-sectional mixed-methods study
Authors: Koroma Osman , Chen Yanhua , Wang Peicheng , Chen Geer , Lin Qian , Cheung Ming Yen , Zhu Jiming 
Published: October 2021

ObjectivesCommunity health workers (CHWs) played important roles in supplementing scarce healthcare workforce in Sierra Leone during the Ebola outbreak, causing the government to launch the National Community Health Worker Policy 2016–2020. This study evaluated this ambitious policy and examined CHWs’ sustainability through their job satisfaction and the underlying factors to inform new policy recommendations, especially the implication for COVID-19 containment.DesignA mixed-methods approach applying structured questionnaires and semistructured interviews.Setting and participants188 CHWs in Bombali District (key Ebola-stricken areas) of Sierra Leone, 184 of them participated in follow-up interviews.Primary and secondary outcome measuresQuantitative and qualitative elements were triangulated to improve robustness of investigation: job satisfaction was measured by the Minnesota Satisfaction Questionnaire (MSQ), and factors associated with job satisfaction were identified through thematic analysis and multivariable logistic regression.ResultsThe MSQ score of CHWs in Sierra Leone was 65.09, extremely low even among low-income and middle-income countries. Five themes (grouped from 16 subthemes) emerged through the semistructured interviews and were tested quantitatively. Payment was CHWs’ top concern. Low stipend and payment tardiness were significantly associated with dissatisfaction. Those with Ebola experience were 5.20 times (95% CI 1.51 to 17.95, p=0.009) more likely to be dissatisfied. This study also found that working conditions, medical material supplies and career development were far from what the CHW policy promised. CHWs’ commitment was the only ‘positive’ theme, and their intrinsic job satisfaction (mean=3.61) was much higher than the extrinsic job satisfaction (mean=2.72).ConclusionsSome critical components of the 2016 National Community Health Worker Policy, aiming to promote CHWs and strengthen primary healthcare, have severe shortfalls in practice. The Sierra Leone government should address the underlying factors that have impaired CHWs’ job satisfaction to ensure sustainability of its CHW network, especially during the combat against COVID-19.
Glucose-lowering drugs and outcome from COVID-19 among patients with type 2 diabetes mellitus: a population-wide analysis in Hong Kong
Authors: Luk Andrea On Yan , Yip Terry C F , Zhang Xinge , Kong Alice Pik Shan , Wong Vincent Wai-Sun , Ma Ronald Ching Wan , Wong Grace Lai-Hung 
Published: October 2021

ObjectivesTo investigate the association between baseline use of glucose-lowering drugs and serious clinical outcome among patients with type 2 diabetes.DesignTerritory-wide retrospective cohort of confirmed cases of COVID-19 between January 2020 and February 2021.SettingAll public health facilities in Hong Kong.Participants1220 patients with diabetes who were admitted for confirmed COVID-19.Primary and secondary outcome measuresComposite clinical endpoint of intensive care unit admission, requirement of invasive mechanical ventilation and/or in-hospital death.ResultsIn this cohort (median age 65.3 years, 54.3% men), 737 (60.4%) patients were treated with metformin, 385 (31.6%) with sulphonylureas, 199 (16.3%) with dipeptidyl peptidase-4 (DPP-4) inhibitors and 273 (22.4%) with insulin prior to admission. In multivariate Cox regression, use of metformin and DPP-4 inhibitors was associated with reduced incidence of the composite endpoint relative to non-use, with respective HRs of 0.51 (95% CI 0.34 to 0.77, p=0.001) and 0.46 (95% CI 0.29 to 0.71, p<0.001), adjusted for age, sex, diabetes duration, glycated haemoglobin (HbA1c), smoking, comorbidities and drugs. Use of sulphonylureas (HR 1.55, 95% CI 1.07 to 2.24, p=0.022) and insulin (HR 6.34, 95% CI 3.72 to 10.78, p<0.001) were both associated with increased hazards of the composite endpoint.ConclusionsUsers of metformin and DPP-4 inhibitors had fewer adverse outcomes from COVID-19 compared with non-users, whereas insulin and sulphonylurea might predict a worse prognosis.