bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding and predicting forest mortality in the western United States using long‐term forest inventory data and modeled hydraulic damage
Authors: Venturas Martin D. , Todd Henry N. , Trugman Anna T. , Anderegg William R. L. 
Published: October 2020

Summary

Global warming is expected to exacerbate the duration and intensity of droughts in the western United States, which may lead to increased tree mortality. A prevailing proximal mechanism of drought‐induced tree mortality is hydraulic damage, but predicting tree mortality from hydraulic theory and climate data still remains a major scientific challenge.

We used forest inventory data and a plant hydraulic model (HM) to address three questions: can we capture regional patterns of drought‐induced tree mortality with HM‐predicted damage thresholds; do HM metrics improve predictions of mortality across broad spatial areas; and what are the dominant controls of forest mortality when considering stand characteristics, climate metrics, and simulated hydraulic stress?

We found that the amount of variance explained by models predicting mortality was limited (R2 median = 0.10, R2 range: 0.00–0.52). HM outputs, including hydraulic damage and carbon assimilation diagnostics, moderately improve mortality prediction across the western US compared with models using stand and climate predictors alone.

Among factors considered, metrics of stand density and tree size tended to be some of the most critical factors explaining mortality, probably highlighting the important roles of structural overshoot, stand development, and biotic agent host selection and outbreaks in mortality patterns.
A career open to the talents—Nurses’ doing and focus during the history
Authors: Falch Lisbeth Aaskov 
Published: October 2020

AbstractBased on a historical and a contemporary fieldwork at a Danish hospital, this article offers a genealogical and philosophical exploration of the development of nurses’ doing and focus within a hospital setting from the 1800 s to the present day. This exploration finds that nurses’ doing has changed during history, which is reflected in their focus. Thus, nurses’ focus has developed from, what the Danish philosopher Uffe Juul Jensen refers to as a situation‐oriented, to a disease‐oriented practice, and while new values are established, the conception of care as a core value in nursing seems to have receded. This article also argues that today's nurses are doing what doctors did in the 19th century. The French philosopher Michel Foucault discusses how things repeat themselves in new ways and new contexts. The nursing profession has become ‘a career open to the talents’ where nurses with the appropriate skills and talents are able to build a career, within which they provide status, position and legitimacy. The conclusion of the article discusses the significance of this development for patients and the nursing profession.
Aiming strategy affects performance‐related factors in biathlon standing shooting
Authors: Köykkä Miika , Ihalainen Simo , Linnamo Vesa , Ruotsalainen Keijo , Häkkinen Keijo , Laaksonen Marko S. 
Published: October 2020

This study focused on investigating differences in shooting performance and performance‐related factors between two different aiming strategies (HOLD, low radial velocity during the approach 0.4‐0.2 seconds before triggering, and TIMING, high radial velocity) in biathlon standing shooting. A total of 23 biathletes fired 8 × 5 standing shots at rest (REST) and 2 × 5 shots during a race simulation (RACE). Shooting performance (hit point distance from the center of the target), aiming point trajectory and postural balance were measured from each shot. Shooting performance was similar both at REST (HOLD 33 ± 5 mm vs TIMING 38 ± 8 mm, P = .111) and in RACE (40 ± 11 mm vs 47 ± 12 mm, P = .194). Better shooting performance was related to smaller distance of the aiming point mean location (REST r = 0.93, P < .001, RACE r = 0.72, P = .018) and higher time spent within ⅔ of the distance of the hit area edge from the center 0.6‐0.0 seconds before triggering (REST r=−0.88, P = .001, RACE r=−0.73, P = .016) in HOLD, and to lower aiming point total velocity 0.6‐0.0 seconds before triggering (REST r = 0.77, P = .009, RACE r = 0.88, P = .001) and less aiming point movement 0.2‐0.0 seconds before triggering (REST r = 0.82, P = .003, RACE r = 0.72, P = .012) in TIMING. Postural balance was related to shooting performance at REST in both groups and in RACE in TIMING. Biathletes using the hold strategy should focus on stabilizing the aiming point before triggering and aiming at the center, whereas biathletes using the timing strategy benefit of decreasing the total velocity during the final approach as well as minimizing the aiming point movement right before triggering.
Fast Fracture Evaluation of Steam Generator Channel Heads Considering High Carbon Macro-Segregation
Authors: Shi Kaikai , Zhang Yixiong , Yang Yu , Zheng Bin , Xie Hai , Fu Xiaolong , Shao Xuejiao 
Published: October 2020

Abstract
The Fracture evaluation is important in the structural integrity analysis of nuclear equipment which is subjected to the effects of neutron irradiation. The increment of ductile and brittle transition temperature is mainly due to the neutron irradiation, thermal ageing and strain ageing. In addition to above these factors, the high carbon macro-segregation of low-alloy steels also increases the risk of fast fracture failure as the carbon positive macro-segregation will lead to the increasing transition temperature of low-alloy steels. In this work, a relationship between the carbon content and the increment of transition temperature is developed and is used to the fast fracture failure analysis of the highest carbon content region in steam generator channel head. Results show that ratio between the calculated stress intensity factor considering safety coefficient suggested by ASME design code and the critical stress intensity factor is less than one, which indicates a safe design for the highest carbon content region in steam generator channel head.
Mode I Stress Intensity Factors for Small Defects in a Large Diameter Threaded Fixing
Authors: Towse Adam 
Published: October 2020

Abstract
Mode I Stress Intensity Factors (SIFs) are presented at the surface and depth positions for shallow defects at the root of the male threads of an M130x4 – 6g / 6H threaded connection. The defects range between 1mm and 5mm in depth, and with an aspect ratio (a/b) between 1 (circular) and 0.1 (elongated). For the lowest a/b ratios, the defects approach the shape of an elongated constant depth defect running circumferentially. Such defects may be produced by preferential fatigue crack growth in the circumferential direction, fatigue crack initiation at the root or as a result of thread forming processes.
The Mode I opening SIFs have been calculated using linear elastic Finite Element Analysis using contour integration. The modelling methodology was verified by comparison with published SIF solutions for semi-elliptical surface-breaking defects in a plate and also an unthreaded bar.
SIFs have been calculated for both membrane and bending loading. The defects were placed at the position of greatest bending stress with the defects symmetric about the bending plane.
SIFs have been calculated for different boundary conditions on the female thread side which affect the flow of load out of the stud, and hence the distribution of force in the stud and the resulting SIFs. The results show that if the flow of load in the stud is reversed, simulating reaction through a nut, then the calculated SIFs are higher than the case where the load is not reversed.
Pipeline Crack Half-Life Versus 1.10 Safety Factor at Next Inspection
Authors: Lamborn Lyndon , Shirband Zeynab , Kwok Ernest 
Published: October 2020

Abstract
Periodic inspection is a proven approach to structural integrity management of transportation systems. This is as true for pipelines as it is for aircraft and railways. Setting the re-inspection interval to ensure imperfections cannot grow to critical dimensions prior to the next inspection is a foundational requirement of this maintenance methodology.
API 1176 delineates two methods for re-inspection interval criteria for pipeline crack threat management: (1) maintaining a safety factor of 1.10 and at least a 30% of wall thickness remaining ligament depth until the next inspection, or (2) inspect at the half-life of the feature with the lowest remaining life taking the end of life being a 1.00 safety factor.
Recent proposed regulatory documents and draft rules have down-selected to Method (1), or at least demonstrating compliance to Method (1), which will require some operators who have only been using Method (2) to safely manage this change.
The two methods are compared for every asset of a large North American operator under current actual operating conditions. The relative conservatism of the two methods is directly compared. Sensitivity to a minimum remaining ligament requirement less than the recommended 30% of wall thickness is explored, and leak/rupture threat differentiation is considered. Implications of the change for a liquids pipeline operator in North America are described.
Buckling of Cylinders due to External Pressure: Experimental Work Compared With Finite Element Stress Analysis
Authors: Nadarajah Chithranjan , Hantz Benjamin F. , Krishnamurthy Sujay 
Published: October 2020

Abstract
The current design by analysis for protection against collapse from buckling in ASME Section VIII, Division 2, B&PV Code [8] has three different methods. However, these is no background bases for the three methods and analyst have found that the elastic plastic collapse analysis will give overly conservative results when compared with design by rule. Therefore, this study was undertaken to resolve this concern and develop a new procedure for buckling analysis to be implemented in the ASME Section VIII, Division 2, B&PV Code, Part 5.
Stress Analysis of In-Service Flare Gas Pipeline System and Equipment Nozzle
Authors: Pu Zhe , Ren Bin , Wang Jielu , Song Pan , Chen Delu 
Published: October 2020

Abstract
The flare system is an indispensable safety facility in petrochemical production. The function of the flare system is to collect the tail gas emitted from the production of each device into the main pipe of the flare, lead it pass through the liquid separation tank and the water seal tank in turn, and finally to the high-altitude flare for combustion and discharge into the atmosphere. The high temperature of flare gas pipeline will cause the pipeline to expand under heat. Due to the large thermal stress caused by the thermal expansion of the pipeline, the load on the nozzle of the connected equipment will be increased, which is easy to cause safety accidents. Taking the flare system of a whole factory as an example, this paper introduced a simple discriminated method to measure the flexibility of the pipeline system. The software CAESAR II was used to establish the model of the main flare pipe and the liquid separation tank in the whole factory. The calculated stress state of the pipe system meets the requirements of ASMEB31.3, and the stress of the liquid separation tank nozzle meets the technical conditions of the manufacturer. It is hoped that this method can provide some reference for the regular inspection of pipelines.
Floor Response Spectrum Method of Multiply Supported Piping System Assisted by Time History Analysis
Authors: Takayama Yoshihiro , Yoshida Ayaka , Nobuyoshi Iriki , Maeda Eiichi 
Published: October 2020

Abstract
The independent support motion response spectrum method (ISM) is currently used for seismic analysis to calculate the response of multiply supported piping with independent inputs of support excitations. This approach may derive considerable overestimation in the combination of group responses under the absolute sum rule of NUREG-1061 [1]. Then authors have developed an advanced method of the ISM approach named SATH (Spectrum Method Assisted by Time History Analysis). In the SATH method, both of floor response spectra and time histories of floor acceleration are used as independent inputs of support excitations. The group responses are summed with correlation coefficients which are calculated by considering each time history of modal response by independent inputs of support excitations. In this paper, the necessity of taking the effects of correlation coefficients for the group responses into account in the ISM approach is examined. The SATH method has advantage to derive a more realistic sum rule of the group responses and applicability for the actual design.
A Hybrid Fatigue Analysis Method for Fatigue Monitor System
Authors: Bai Xiaoming , Xie Hai , Shi Kaikai , Ai Honglei , Zheng Liangang , Mi Xue 
Published: October 2020

Abstract
During the operation of nuclear power plants (NPPs), the thermal fatigue is one of the most severe aging factors for the components. Therefore, it is significant to monitor the fatigue degradation of components caused by the thermal variation. Moreover, the fatigue monitor result is widely used in the life extension of NPPs. From this viewpoint, the Nuclear Power Institute of China (NPIC) has developed an advanced fatigue monitor system which can classify the operational transient and calculate the cumulative fatigue usage. In classical fatigue monitor system, two methods are widely used to calculate the cumulative fatigue usage. They are the cycle based method and the stress based method. In the cycle based method, the operational transient is classified into a conservative design transient, and then the remaining times of design transient is used to describe the fatigue condition. Obviously, the cycle based method is fast, but conservative. In the stress base method, the monitored thermal data is used to calculate stress and then do the fatigue analysis. This method is more accurate than the cycle based one, but this method is very time-consuming. In present work, a hybrid fatigue analysis of cycle based and stress based method is proposed. In this method, an off-line stress based fatigue database is developed using finite element method. The cycle based method is adopted to determine the transient effects. However, according to the off-line database, the consumed transient time is no longer an integer, but is a fraction to describe the difference between the cumulative fatigue usage of design transient and the one of operational transient.
A52M/SA52 Dissimilar Metal RPV Repair Weld: Experimental Evaluation and Post-Weld Characterizations
Authors: Virkkunen Iikka , Peltonen Mikko , Sirén Henrik , Nevasmaa Pekka , Huotilainen Caitlin , Keinänen Heikki , Kuutti Juha , Lambai Aloshious , Mohanty Gaurav , Honkanen Mari 
Published: October 2020

Abstract
Aging management of the existing fleet of nuclear power plants is becoming an increasingly important topic, especially as many units are approaching their design lifetimes or are entering long-term operation. As these plants continue to age, there is an increased probability for the need of repairs due to extended exposure to a harsh environment. It is paramount that qualified and validated solutions are readily available.
A repair method for a postulated through cladding crack into the low alloy steel of a nuclear power plant’s reactor pressure vessel has been investigated in this study. This paper is part of larger study that evaluates the current possibilities of such repair welds. The present paper documents the weld-trials and method selection. A parallel paper describes numerical simulations and optimization of weld parameters. The presented weld-trial represents a case where a postulated crack has been excavated and repaired using a nickel base Alloy 52M filler metal by gas metal arc welding-cold metal transfer with a robotic arm. A SA235 structural steel has been used as a base material in this weld-trial. No pre-heating or post-weld heat treatment will be applied, as it would be nearly impossible to apply these treatments in a reactor pressure vessel repair situation.
While Alloy 52M presents good material properties, in terms of resistance to environmentally assisted degradation mechanisms, such as primary water stress corrosion cracking, it is notoriously difficult to weld. Some difficulties and challenges during welding include a sluggish weld puddle, formation of titanium and/or aluminium oxides and its susceptibility to lack of fusion defects and weld metal cracking, such as ductility dip cracking and solidification cracking. Moreover, gas metal arc welding-cold metal transfer is not traditionally used in the nuclear industry. Nonetheless, it presents some interesting advantages, specifically concerning heat input requirements and automation possibilities, as compared to traditional welding methods.
The mechanical properties, in terms of indentation hardness, and microstructure of a weld-trial sample have been evaluated in this study. The fusion boundary and heat affected zone were the main areas of focus when evaluating the mechanical and microstructural properties. Detailed microstructural characterization using electron backscatter diffraction and nanoindentation were performed across the weld interface. Based on these results, the gas metal arc welding cold metal transfer is seen as a potential high-quality weld method for reactor pressure vessel repair cases.
Brittle Fracture of Stainless Steel Dissimilar Metal Welds in the Upper Shelf of the Brittle-to-Ductile Transition Range
Authors: Ben Salem G. , Chapuliot S. , Blouin A. , Bompard P. , Jacquemoud C. 
Published: October 2020

Abstract
Stainless steel dissimilar metal welds (SS DMW) are widely used within the French nuclear power plants where they connect the main components (pressure vessel, pressurizer, steam generator) made of low alloy ferritic steel to the primary circuit pipes made of austenitic stainless steel. Because of their heterogeneous microstructure and mechanical properties, these junctions are critical components for the structure integrity and their fracture resistance has to be demonstrated for all the nominal or accidental operating conditions. This work aims at building a model to evaluate the risk of brittle fracture of the SS DMW in the upper shelf of the brittle-to ductile transition range. The observation of the microstructures around the fusion line revealed a martensitic layer and a fully austenitic zone, which undergo an important carbides precipitation during the post-weld heat treatment and form a narrow hard layer of carburized martensite and austenite. Fracture toughness tests were then carried out on CT specimens in the brittle-to-ductile temperature range and helped identify the MA interface (between martensite and austenite) as the weakest region in the SS DMW because of an intergranular fracture mechanism initiated at the carbides-rich interface. This mechanism was consistently observed for specimens with fatigue precrack fronts in the hard layer. To model the brittle behavior of the MA interface, the stress distributions on the MA interface were calculated with FE numerical simulation of the fracture toughness tests and a 1D 3 parameters Weibull model based on a threshold stress and a threshold length was identified for the CT specimens. The temperature dependence of the model parameters was finally studied and the effect of temperature on the intergranular fracture mechanism of the MA interface was explored.
Evaluation of Mechanical and Corrosion Properties of Base Metal and HAZ Having ASS 304L Forgings Containing Ferrite
Authors: Patel Ritesh , Shah Hardik , Dutt Jimmy 
Published: October 2020

Abstract
Austenitic Stainless Steel type 304L is being widely used for fabrication due to excellent corrosion resistance and good weldability. Ferrite (3–10%) is needed in weld metal to prevent hot cracking during welding, however, base metal should preferably not contain any ferrite. It is observed that thick forged SS304L components may have small percentage of ferrite depending on the chemical composition, forging parameters including intermediate soaking cycle and final solution annealing heat treatment cycle. Little study or information is available on effect of ferrite in base metal on weld/Heat Affected Zone (HAZ) properties.
Present study is aimed to evaluate mechanical and corrosion properties of weldment produced with base metal containing 2–4% of ferrite. Forged tubes with two different levels of delta ferrite, with &lt; 0.5% & 2–4%, were welded to Plates with &lt; 0.5% delta ferrite using Mechanized Gas Tungsten Arc Welding (GTAW) process with Inner Bore Welding Technique. Tensile test, Impact test and Hardness test were performed on base metal & HAZ in as-welded condition for both the cases. Microstructure examination in HAZ and Intergranular Corrosion (IGC) test were also performed for both the cases. Results of mechanical tests, microstructure examination and IGC test have been compared between base metal/HAZ of &lt; 0.5% and 2–4% Ferrite base metal. No significant difference has been observed in test result of tubes with 2–4% delta ferrite as compared to tubes with &lt; 0.5% delta ferrite.
Comparative Evaluation of Plastic Design Methods for Fatigue Assessment of a Nuclear Class 1 Piping Nozzle
Authors: Clarkson David M. , Bell Christopher D. , Mackenzie Donald 
Published: October 2020

Abstract
Design-by-analysis (DBA) procedures for Nuclear Class 1 pressure vessels such as those prescribed within ASME Boiler and Pressure Vessel Code (BPVC) Section III, provide rules to demonstrate assurance against fatigue failure. Two general assessment routes exist, linear finite element analysis (FEA) with stress categorization and elastic-plastic penalty factors, or nonlinear FEA with direct multiaxial strain evaluation. Whilst the elastic design route possesses many practical advantages, it is widely acknowledged to be very conservative, sometimes unacceptably so. At the cost of additional analysis effort, plastic design methods can provide a more appropriate evaluation of fatigue usage, potentially avoiding unnecessary design modifications and reducing the burden of in-service inspection requirements.
This paper presents and compares various strain measures proposed for ASME III plastic fatigue analysis within the technical literature. A case study of a typical pressurized water reactor (PWR) main coolant line (MCL) piping nozzle subjected to pressure and thermal loads is presented. The influence of strain measure selection on the FE-derived strain concentration (Ke) factors is examined. Some important considerations for calculation of realistic Ke factors in ASME III are further discussed.