bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluid-Structure Interaction and Co-Simulation: Analysis of a Beam-Supported Sphere for VIV Application
Authors: Ardito Raffaele , Perotti Federico , Mandelli Simone , Novarina Davide , Malavasi Stefano 
Published: November 2014

The recent developments in numerical tools and computing resources seem to provide a suitable environment to perform numerical analyses of Fluid-Structure Interaction problems. The Co-Simulation technique, in particular, develops the idea of coupling a CFD software with a structural one in order to simulate complex FSI phenomena with a partitioned approach, stressing the concept of software modularity. In this way, it is possible to adopt software tools at the cutting edge of technology. Nonetheless, several difficulties may arise in the choice of the partitioning scheme and of the algorithmic details for the step-by-step time integration.
This paper deals with the application of the Co-Simulation technique to a benchmark case experimentally investigated in previous works: the vortex-induced vibrations (VIV) of a beam supported sphere (that is, a sphere fixed to the end of a slender cantilever beam) in a free surface flow. This problem is challenging although apparently simple and it seems quite absent from literature so far. In this paper, the computational issues are thoroughly investigated and the model is validated by comparison with the experimental data. In this way, a robust framework is created in order to deal with VIV problems.
Automated Ultrasonic Testing Optimizes Integrity Evaluations for Underground Piping Inspections
Authors: Cilluffo Graig 
Published: November 2014

This paper will provide an overview of a recent buried piping inspection project leveraging automated ultrasonic testing methods to evaluate internal raw water corrosion at a reliably-operating, nuclear power plant. Discussion of current piping inspection practices for resolving non-planar flaws in raw water piping will be provided, emphasizing inspection performance requirements and a pilot project using automated scanning to optimize inspection value while minimizing field time and costs.
Contents include past buried piping integrity inspection scope / method selection, details on techniques and critical success factors for the project relative to integrity needs, lessons learned from field implementation, further experience from subsequent related inspections using automated and manual techniques for comparison, and recommended actions for future integrity assessments and mitigating actions. Results provided clear justification for this new approach above traditional evaluations performed in the past and may represent a best industry practice for buried pipe assessment.
While targeting buried piping applications, this method can be applied to many systems / locations vulnerable to corrosion. Guidance on applications, limitations, and areas for improvement are also provided from a project / field perspective.
Piping Corrosion Rate and Remaining Life Basis: Commercializing Conservatism in First Time Inspections
Authors: Cilluffo Graig 
Published: November 2014

This paper sets forth guidance on how to establish a justifiable internal corrosion rate following a first time inspection to predict re-inspection or replacement timing for raw water piping. A novel approach leverages actual plant-wide piping inspection data, leak history, repair history, and corrosion monitoring results together to inform integrity decisions based on experience at a reliably-operating, nuclear power plant. Data is applied on a risk-conscious basis to piping systems based upon failure consequence and uncertainty and differs from the typical approach of reporting location-specific, time-averaged rates. Excavation and in-plant inspection results can now inform commercially-friendly conservatism that reduces leak risks while also minimizing total inspection and maintenance costs.
While directly applicable to buried piping, this method can be applied to any corrosive system / location. Information is presented in a format that readers can readily follow to develop similar justifications for their own sites / systems. Guidance on applications, limitations, and areas for improvement are also provided.
ASME Section III Flaw Tolerance Sample Problem for Fatigue Design of Nuclear System Components
Authors: Dewees David J. , Hirschberg Paul , Reinhardt Wolf , Stevens Gary L. , Roarty David H. , Gosselin Steve , Wright Keith , Damiani Thomas M. 
Published: November 2014

An ASME Section III Task Group (TG) was formed in 2012 to develop alternate rules for the design assessment of Section III Class 1 nuclear components subject to fatigue service with environmental effects. Specifically, a flaw tolerance approach is being investigated based on similar methodology to that found in ASME Section XI Nonmandatory Appendix L. A key initial task of the TG (which reports to the Section III Working Group on Environmental Fatigue Evaluation Methods) was to develop and solve a detailed sample problem. The intent of the sample problem was to illustrate application of proposed rules, which will be documented as a Section III Code Case with a supporting technical basis document. Insights gained from round robin solution of the sample problem are presented and discussed in this paper. The objective of documenting the findings from the sample problem are to highlight the observed benefits and limitations of the proposed procedures, particularly how rules typically associated with in-service experience might be adapted into design methods.
The sample problem is based on a heavy-walled stainless steel nozzle that meets cumulative fatigue usage requirements in air (i.e., usage factor, U, without reactor water environment effects less than unity), but fails to meet usage factor requirements when environmental fatigue effects are applied.
The sample problem demonstrates that there is a class of problems dominated by severe thermal transients where fatigue initiation is predicted based on elastic methods including environmental effects, but fatigue crack propagation results are acceptable. Preliminary conclusions are drawn based on the results of the sample problem, and the next steps are also identified.
Validation Approaches for Weld Residual Stress Simulation
Authors: Hill Michael R. , Tran Minh N. , Broussard John E. 
Published: November 2014

In assessment of stress corrosion cracking behavior of susceptible welded materials, the contribution of weld residual stress is a key input for stress intensity factor calculations, which in turn are used to determine anticipated crack growth and to plan for inspection or repair. Without accurate weld residual stress information, it is challenging to develop an optimal plan for plant management. Weld residual stress simulations, based on non-linear finite element computations, provide a means to estimate residual stresses in components. However, there is no established, consensus approach for weld residual stress model validation, which could be used to judge model quality, specifically with respect to the influence of residual stress output on plant management decisions. A consensus model validation approach would benefit a broad range of stakeholders in pressure vessel technology.
The paper provides technical detail of example approaches for weld residual stress model validation, and applies these approaches to a set of weld residual stress model outputs that were developed in the context of an industry round robin. The set of outputs is from Phase 2a of the international round robin organized cooperatively by the U.S. Nuclear Regulatory Commission and the Electric Power Research Institute. Example validation approaches include comparisons of output from one model with output from other models, as well as comparisons of model output with data from residual stress measurements. The figures of merit used for comparisons range from simple (e.g., evaluation of mechanical section forces) to complex (e.g., comparison of predicted crack growth behavior). Applying a range of validation approaches provides information for use within the technical community, to support development of a consensus approach for weld residual stress model validation.
Analytical Model of Nuclear Environmental Effects With Piezoelectric Wafer Active Sensors
Authors: Lin Bin , Yu Lingyu , Giurgiutiu Victor , Gresil Matthieu , Mendez Torres Adrian E. 
Published: November 2014

The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS) for pipe and vessels (PVP) application. For example, nuclear dry cask storage system (DCSS) is a safety-critical facility in need of monitoring over prolonged periods of time. Technologies for the diagnosis and prognosis of PVP systems can improve verification of the health of the structure that can eventually reduce the likelihood of inadvertently failure of a component.
The past two decades have witnessed an extensive sensor technology development using permanently installed piezoelectric wafer active sensors (PWAS) for structural health monitoring (SHM). PWAS have emerged as one of the major SHM technologies developed particularly for generating and receiving acousto-ultrasonic waves for the purpose of continuous monitoring and diagnosis. Durability and survivability of PWAS under nuclear environmental exposures has been tested preliminarily. However, the analytical model of PWAS based sensor and sensing system has not been developed with adequate solutions and guideline. This paper presents a study on an analytical model of nuclear environmental effects with PWAS. Environmental variability of a Nuclear-SHM system includes changes in both the sensors and the sensing methodology including acoustic emission (AE), guided ultrasonic waves (GUW), and electro-mechanical impedance spectroscopy (EMIS). We considered the environmental variability considers the effects of temperature changes and radiation. We superposed these changes on the analytical models and determined how much the structural sensing signals change is due to these environment effects for the DCSS system. The analytical modeling of various structural sensing methods to environmental disturbances was studied and the potential of PWAS as irradiation sensors for PVP applications was explored. The paper ends with conclusions and suggestions for further work.
Using Explicit Finite Element Analysis to Simulate the Structural Damage Associated With an Internal Detonation in a Heat Exchanger
Authors: Prueter Phillip E. 
Published: November 2014

Developing the realistic blast loading associated with an internal detonation occurring within a pressure vessel or heat exchanger is challenging. Unlike evaluation of external blast loading on structures due to far-field explosions, where typical overpressure-time histories can be reasonably defined based on empirical data, investigating confined detonations presents additional complications. The subsequent impulsive peak reflected overpressure from confined detonations acting on a structure can be extremely high due to the close proximity of the blast source to the vessel wall or pressure boundary. This establishes the possibility of significant structural damage for process equipment subjected to an internal detonation, even for relatively modest amounts of concentrated explosive products.
This paper discusses the underlying theory of blast analysis and examines the practical application of non-linear, finite element based, explicit computational techniques for simulating the load acting on a structure due to internal and external blasts. The investigation of a recent, real-life industry failure of a heat exchanger due to a suspected internal detonation is discussed. Explicit, three-dimensional blast analysis is performed on the heat exchanger in question, and an internal detonation is simulated to reasonably replicate the considerable damage actually observed in the field. This analysis permits the determination of an approximate amount of concentrated product that caused the accidental explosion; that is, the plausible equivalent amount of explosives is back-calculated based on the predicted damage to the finite element model of the equipment in question. Computational iterations of varying charge amounts are performed and the predicted amount of permanent damage is documented so sensitivity to the hypothesized charge amount can be quantified. Furthermore, explicit blast analysis of nearby equipment is performed.
In this investigation, computational results for both the heat exchanger (subjected to internal blast loading) and surrounding equipment (subjected to external blast loading) are in good agreement with the measured plastic deformations and failure modes that were actually observed in the field. Commentary on the likely detonation event that caused the significant damage observed is provided. Additionally, an advanced finite element failure criterion that is driven by plastic yielding is employed where portions of the computational model are removed from the simulation once a user-defined strain threshold is reached. This approach facilitates simulation of the gross heat exchanger pressure boundary failure actually observed in this case. The explicit finite element based analyses discussed in this study reasonably predict the structural response and damage characteristics corresponding to a recent, real-life industry failure.
Local vs. Global Ratcheting in Cracked Structures
Authors: Adibi-Asl R. , Reinhardt Wolf 
Published: November 2014

The classical approaches in shakedown analysis are based on the assumption that the stresses are eventually within the elastic range of the material everywhere in a component (elastic shakedown). Therefore, these approaches are not very useful to predict the ratcheting limit (ratchet limit) of a cracked component/structure in which the magnitude of stress locally exceeds the elastic range at any load, although in reality the configuration will certainly permit plastic shakedown. The Non-Cyclic Method (NCM) has been proposed recently to determine both the elastic and the plastic ratchet boundary of a component or structure under cyclic loading by generalizing the static shakedown theorem (Melan’s theorem). The proposed method is based on decomposing the loading into mean (time invariant) and fully reversed components. When a cracked structure is subjected to cyclic loading, the crack and its vicinity behave differently (local) than the rest of the structure (global). The crack may propagate during the application of cyclic loading. This will affect both local and global behavior of the cracked structure.
This paper investigates global and local ratcheting of the cracked structures using the NCM and fracture mechanic parameters.
Skirt Splice Methods for Tall Pressure Vessel Towers
Authors: Seipp Trevor G. , Morrison Shawn W. , Avery Alicia C. 
Published: November 2014

The design of tall pressure vessel towers may be affected by transportation limitations on the overall length of the vessel-plus-skirt. Additionally, process considerations set minimum elevations for the pressure vessel, and plant conditions may dictate whether the vessel needs to be set on a foundation or in a structure. Occasionally, these limitations collide, resulting in a requirement for a longer skirt than can be transported. To enable transportation, the vessel skirt may need to be spliced.
There are multiple methods for which the skirt can be spliced: welded or re-welded at site, sleeve-and-bolt, double-sleeve-and-bolt, and flanged. This paper presents these various methods, and presents an overview of the different design methodologies and considerations for the flanged approach. Design considerations and evaluations necessary for the design and consideration of fabrication tolerances are presented. A case study is introduced for context.
Development of Simplified Empirical Phase Transformation Model for Use in Welding Residual Stress Simulations
Authors: O’Meara Nicholas , Francis John A. , Smith Simon D. , Withers Philip J. 
Published: November 2014

The level and distribution of residual stresses in welds arises from the complex thermo-mechanical history of heat flow and thermal expansion at very high temperatures. It is not possible to make assessments of these with the methods that are used to determine service stresses. Simulation techniques have been developed over many years making it increasingly possible to predict residual stresses. These models need accurate materials data including, where applicable, the effect of phase transformations. In nuclear reactor pressure vessel welds, it is necessary to consider welding as a metallurgical problem as well as a thermo-mechanical one and FE simulations of these require a wide range of material data in order to create suitable input parameters.
It is crucial that models of ferritic steel welds simulate the effects of phase transformations because the different phases have different thermal expansion coefficients. Partly due to differences in thermal expansion coefficient attributed to the different phases, but more significantly because of the associated transformation strain and transformation plasticity. Further to this, predicting the distribution of the phase fractions enables structural simulations to account for the distribution of mechanical properties throughout a weld. In this work, a simplified approach to producing an empirical model to simulate phase transformations in SA-508 Gr3 pressure vessel steel is presented. A commercial finite element package is used to implement the model which calculates the volume fraction of bainite, martensite and austenite and the thermal strains that evolve over the thermal excursions. The results of these FE simulations are compared to experimental data.
Profiling the Training Practices and Performance of Elite Rowers
Authors: Tran Jacqueline , Rice Anthony J. , Main Luana C. , Gastin Paul B. 
Published: November 2014

Purpose:To investigate changes in physiology, performance, and training practices of elite Australian rowers over 6 mo.Methods:Twenty-one elite rowers (14 male, 7 female) were monitored throughout 2 phases: phase 1 (specific preparation) and phase 2 (domestic competition). Incremental tests and rowing-ergometer time trials over 100, 500, 2000, and 6000 m were conducted at the start of the season, midseason, and late season. Weekly external (frequency, duration, distance rowed) and internal (T2minute method) loads are reported.Results:Heavyweight male rowers achieved moderate improvements in VO2max and power at VO2max. Most other changes in physiology and performance were small or unclear. External loads decreased from phase 1 to phase 2 (duration 19.3 to 18.0 h/wk, distance rowed 140 to 125 km/wk, respectively). Conversely, internal loads increased (phase 1 = 19.0 T2hours, phase 2 = 20.3 T2hours). Low-intensity training predominated (~80% of training hours at T1 and T2), and high-intensity training was greater in phase 2. Training was rowing-focused (68% of training duration), although 32% of training time was spent in nonspecific modes. The distribution of specificity was not different between phases.Conclusion:Physiology and performance results were stable over the 6-mo period. Training-load patterns differed depending on the measure, highlighting the importance of monitoring both external and internal loads. The distribution of intensity was somewhat polarized, and substantial volumes of nonspecific training were undertaken. Experimental studies should investigate the effects of different distributions of intensity and specificity on rowing performance.
Sensitivity of the Yo-Yo Intermittent Recovery Test and Cardiac Autonomic Responses to Training in Futsal Players
Authors: de Freitas Victor H. , Pereira Lucas A. , de Souza Eberton A. , Leicht Anthony S. , Bertollo Maurizio , Nakamura Fábio Y. 
Published: November 2014

Purpose:This study examined the sensitivity of maximal (Yo-Yo Intermittent Recovery [IR] 1 and 2) and submaximal (5’-5’) tests to identify training adaptations in futsal players along with the suitability of heart-rate (HR) and HR-variability (HRV) measures to identify these adaptations.Methods:Eleven male professional futsal players were assessed before (pretraining) and after (posttraining) a 5-wk period. Assessments included 5’-5’ and Yo-Yo IR1 and IR2 performances and HR and HRV at rest and during the IR and 5’-5’ tests. Magnitude-based-inference analyses examined the differences between pre- and posttraining, while relationships between changes in variables were determined via correlation.Results:Posttraining, Yo-Yo IR1 performance likely increased while Yo-Yo IR2 performance almost certainly increased. Submaximal HR during the Yo-Yo IR1 and Yo-Yo IR2 almost certainly and likely, respectively, decreased with training. HR during the 5’-5’ was very likely decreased, while HRV at rest and during the 5’-5’ was likely increased after training. Changes in both Yo-Yo IR performances were negatively correlated with changes in HR during the Yo-Yo IR1 test and positively correlated with the change in HRV during the 5’-5’.Conclusions:The current study has identified the Yo-Yo IR2 as more responsive for monitoring training-induced changes of futsal players than the Yo-Yo IR1. Changes in submaximal HR during the Yo-Yo IR and HRV during the 5’-5’ were highly sensitive to changes in maximal performance and are recommended for monitoring training. The 5’-5’ was recommended as a time-efficient method to assess training adaptations for futsal players.
Evolution and Transmission Patterns of Extensively Drug-Resistant Tuberculosis in China
Authors: Wang Feifei , Shao Lingyun , Fan Xiaoping , Shen Yaojie , Diao Ni , Jin Jialin , Sun Feng , Wu Jing , Chen Jiazhen , Weng Xinhua , Cheng Xunjia , Zhang Ying , Zhang Wenhong 
Published: November 2014

ABSTRACT

The emergence and transmission of extensively drug-resistant tuberculosis (XDR-TB) pose an increasing threat to global TB control. This study aimed to identify the patterns of evolution and transmission dynamics of XDR-TB in populations in a region of China where TB is highly endemic. We analyzed a total of 95 XDR-TB isolates collected from 2003 to 2009 in Chongqing, China. Eight drug resistance genes covering 7 drugs that define XDR-TB were amplified by PCR followed by DNA sequencing. Variable-number tandem repeat 16-locus (VNTR-16) genotyping and genotypic drug resistance profiles were used to determine the evolution or transmission patterns of XDR-TB strains. Our results indicated that the Beijing genotype was predominant (85/95 [89.5%]) in XDR-TB strains, and as many as 40.0% (38/95) of the isolates were distributed into 6 clusters based on VNTR-16 genotyping and drug resistance mutation profiles. All isolates of each cluster harbored as many as six identical resistance mutations in the drug resistance genes
rpoB
,
katG
,
inhA
promoter,
embB
,
rpsL
, and
gidB
. Among the nine cases with continuous isolates from multidrug-resistant (MDR) to XDR-TB, 4 cases represented acquired drug resistance, 4 cases were caused by transmission, and 1 case was due to exogenous superinfection. The XDR-TB epidemic in China is mainly caused by a high degree of clonal transmission, but evolution from MDR to XDR and even superinfection with a new XDR strain can also occur.