bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploration of plant growth and development using the European Modular Cultivation System facility on the International Space Station
Authors: Kittang A. ‐I. , Iversen T. ‐H. , Fossum K. R. , Mazars C. , Carnero‐Diaz E. , Boucheron‐Dubuisson E. , Le Disquet I. , Legué V. , Herranz R. , Pereda‐Loth V. , Medina F. J.
Published: January 2014

Space experiments provide a unique opportunity to advance our knowledge of how plants respond to the space environment, and specifically to the absence of gravity. The European Modular Cultivation System (EMCS) has been designed as a dedicated facility to improve and standardise plant growth in the International Space Station (ISS). The EMCS is equipped with two centrifuges to perform experiments in microgravity and with variable gravity levels up to 2.0 g. Seven experiments have been performed since the EMCS was operational on the ISS. The objectives of these experiments aimed to elucidate phototropic responses (experiments TROPI‐1 and ‐2), root gravitropic sensing (GRAVI‐1), circumnutation (MULTIGEN‐1), cell wall dynamics and gravity resistance (Cell wall/Resist wall), proteomic identification of signalling players (GENARA‐A) and mechanism of InsP3 signalling (Plant signalling). The role of light in cell proliferation and plant development in the absence of gravity is being analysed in an on‐going experiment (Seedling growth). Based on the lessons learned from the acquired experience, three preselected ISS experiments have been merged and implemented as a single project (Plant development) to study early phases of seedling development. A Topical Team initiated by European Space Agency (ESA), involving experienced scientists on Arabidopsis space research experiments, aims at establishing a coordinated, long‐term scientific strategy to understand the role of gravity in Arabidopsis growth and development using already existing or planned new hardware.
Comparison of Botrytis cinerea airborne inoculum progress curves from raspberry, strawberry and grape plantings
Authors: Carisse O. , Tremblay D. M. , Lefebvre A.
Published: January 2014

Airborne Botrytis cinerea conidia concentration was monitored using a new qPCR assay in strawberry, raspberry and grape plantings in 2010, 2011 and 2012. Airborne inoculum progress curves (IPCs) were constructed and analysed using the maximum ACC (Ymax), ACC during the flowering period (Yf), and area under the IPC (AUIPCstd) and descriptors derived from fitting growth models. The structure of IPCs was examined by conducting multivariate principal component analyses. The dimensionality of the data was reduced to two principal components (PCs) accounting for 86·12% of the variation. All descriptors derived from growth models were associated with PC1 and descriptors derived directly from the data were associated with PC2. Based on principal component analysis, the structure of the IPCs varied with the crop, with AUIPCstd values of 28·18, 42·79 and 155·83 and Yf values of 53·58, 20·14 and 142·54 conidia m−3 h−1 in raspberry, strawberry and grape, respectively. Time to 50% of the maximum inoculum concentration was lower in raspberry and strawberry than in grape. The IPCs monitored in raspberry were characterized by narrow ranges for mean absolute rate (0·012–0·016) and AUIPCstd (16·80–48·85), the IPCs monitored in strawberry were characterized by wide ranges for mean absolute rate (0·031–0·080) and AUIPCstd (12·31–98·39), and the IPCs monitored in grape crops were characterized by a lower mean absolute rate (0·006–0·012) and a higher AUIPCstd (50·95–335·14).
Rapid detection and quantification of viable potato cyst nematodes using qPCR in combination with propidium monoazide
Authors: Christoforou Μ. , Pantelides I. S. , Kanetis L. , Ioannou N. , Tsaltas D.
Published: January 2014

Potato cyst nematodes (PCN), Globodera pallida and Globodera rostochiensis, are obligate parasites of solanaceous plants, causing severe losses in several potato growing areas throughout the world. To date, management of PCN is related to nematode population densities estimated as eggs per gram of soil, without considering the actual number of viable juveniles within the cysts. In classical nematology, the standard method to determine PCN viability is based on a staining assay, using Meldola's blue dye (MB) followed by microscopic visualization of MB‐treated nematodes. Although MB is considered to be reliable in staining embryonated juveniles within eggs and cysts, it is a time‐ and labour‐consuming assay. In the present work, a real‐time PCR (qPCR)‐based method combined with propidium monoazide (PMA), a photoreactive DNA‐intercalating dye, was developed for the quantification of viable PCN. This dye renders exposed DNA of dead cells unable to be amplified by PCR, and thus only DNA from viable/intact PCN juveniles is amplified and detected. The novelty of the present method lies in the simultaneous quantitative and qualitative estimation of viable PCN inocula using species‐specific primers and TaqMan probes. The PMA–qPCR viability method (v‐PCR) developed for the two Globodera species successfully discriminated dead from living specimens in heat‐treated samples and eggs in old and newly formed cysts. Interestingly, the detection of DNA from 34‐year‐old nematode cysts stored at room temperature was observed. In conclusion, the proposed v‐PCR method should prove to be very useful for the routine determination of PCN viability from field samples.
Biological control agents (BCAs) of verticillium wilt: influence of application rates and delivery method on plant protection, triggering of host defence mechanisms and rhizosphere populations of BCAs
Authors: Angelopoulou D. J. , Naska E. J. , Paplomatas E. J. , Tjamos S. E.
Published: January 2014

Verticillium dahliae causes severe yield reductions in a variety of important annual crops worldwide. Control of verticillium wilt has relied on soil fumigation; however, the use of the main soil fumigant, methyl bromide, has been banned in the European Union since 2010, creating a demand for novel crop protectants. As such, the use of biocontrol agents (BCAs) is an appealing management strategy. Prerequisites for the development of a successful BCA are an understanding of the modes of action of the antagonist, its ecological fitness and an efficient and economically feasible delivery system. Therefore, two BCAs (Paenibacillus alvei K165 or the nonpathogenic Fusarium oxysporum F2) and two release strategies (seed coating or amendment of the transplant soil plug) were assessed against verticillium wilt of aubergine (eggplant). Mixing the transplant soil plug with K165 or F2, at a rate of 10 and 20% (v/v), respectively, reduced verticillium wilt symptom development. Furthermore, a positive correlation was revealed between the release strategy and the BCA rhizosphere population. Correlation analysis also showed that disease severity was negatively correlated to the rhizosphere size of the BCA population. In addition, qPCR analysis showed that both BCAs induced the expression of the pathogenesis‐related (PR) proteins PR1 and PR4 in the stem of aubergines before and after inoculation with V. dahliae in a manner that suggests a link with the rhizosphere size of the BCA population.
Seeing the Forest for the Trees: An Atlas of the Politics–Administration Dichotomy
Authors: Georgiou Ion
Published: January 2014

Recent years have seen attempts to make sense of the politics–administration dichotomy. Triangulating among historical research, empirical observations, new models of interaction between politicians and administrators, and the division of the literature into “schools,” novel ways of understanding and examining the dichotomy have developed. These have been largely thematic and have revealed the extent of a literature spanning more than 120 years. Because of its size, a complementary structural analysis of the literature now not only is conceivably useful but also can offer means for approaching it. This article offers an atlas—that is, a series of visual maps, accompanied by associated statistics and interpretations—that can assist researchers in their travels through the territory of the dichotomy. Ten ways of tackling the literature are presented, culminating in an initial reading list that covers the breadth of dichotomy research, thus providing an epistemological foundation for those who wish to enter the territory.
Deep incision in an Aptian carbonate succession indicates major sea‐level fall in the Cretaceous
Authors: Bover‐Arnal Telm , Salas Ramon , Guimerà Joan , Moreno‐Bedmar Josep Anton
Published: January 2014

Long‐term relative sea‐level cycles (0·5 to 6 Myr) have yet to be fully understood for the Cretaceous. During the Aptian, in the northern Maestrat Basin (Eastern Iberian Peninsula), fault‐controlled subsidence created depositional space, but eustasy governed changes in depositional trends. Relative sea‐level history was reconstructed by sequence stratigraphic analysis. Two forced regressive stages of relative sea‐level were recognized within three depositional sequences. The first stage is late Early Aptian age (intra Dufrenoyia furcata Zone) and is characterized by foreshore to upper shoreface sedimentary wedges, which occur detached from a highstand carbonate platform, and were deposited above basin marls. The amplitude of relative sea‐level drop was in the order of tens of metres, with a duration of <1 Myr. The second stage of relative sea‐level fall occurred within the Late Aptian and is recorded by an incised valley that, when restored to its pre‐contractional attitude, was >2 km wide and cut ≥115 m down into the underlying Aptian succession. With the subsequent transgression, the incision was backfilled with peritidal to shallow subtidal deposits. The changes in depositional trends, lithofacies evolution and geometric relation of the stratigraphic units characterized are similar to those observed in coeval rocks within the Maestrat Basin, as well as in other correlative basins elsewhere. The pace and magnitude of the two relative sea‐level drops identified fall within the glacio‐eustatic domain. In the Maestrat Basin, terrestrial palynological studies provide evidence that the late Early and Late Aptian climate was cooler than the earliest part of the Early Aptian and the Albian Stage, which were characterized by warmer environmental conditions. The outcrops documented here are significant because they preserve the results of Aptian long‐term sea‐level trends that are often only recognizable on larger scales (i.e. seismic), such as for the Arabian Plate.
Facies analysis and palaeoclimatic significance of ironstones formed during the Eocene greenhouse
Authors: Salama Walid , El Aref Mortada , Gaupp Reinhard
Published: January 2014

Lower and middle Eocene ironstone sequences of the Naqb and Qazzun formations from the north‐east Bahariya Depression, Western Desert, Egypt, represent a proxy for early Palaeogene climate and sea‐level changes. These sequences represent the only Palaeogene economic ooidal ironstone record of the Southern Tethys. These ironstone sequences rest unconformably on three structurally controlled Cenomanian palaeohighs (for example, the Gedida, Harra and Ghorabi mines) and formed on the inner ramp of a carbonate platform. These palaeohighs were exposed and subjected to subaerial lateritic weathering from the Cenomanian to early Eocene. The lower and middle Eocene ironstone sequences consist of quiet water ironstone facies overlain by higher energy ironstone facies. The distribution of low‐energy ironstone facies is controlled by depositional relief. These deposits consist of lagoonal, burrow‐mottled mud‐ironstone and laterally equivalent tidal flat, stromatolitic ironstones. The agitated water ironstone facies consist of shallow subtidal–intertidal nummulitic–ooidal–oncoidal and back‐barrier storm‐generated fossiliferous ironstones. The formation of these marginal marine sequences was associated with major marine transgressive–regressive megacycles that separated by subaerial exposure and lateritic weathering. The formation of lateritic palaeosols with their characteristic dissolution and reprecipitation features, such as colloform texture and alveolar voids, implies periods of humid and warm climate followed major marine regressions. The formation of the lower to middle Eocene ironstone succession and the associated lateritic palaeosols can be linked to the early Palaeogene global warming and eustatic sea‐level changes. The reworking of the middle Eocene palaeosol and the deposition of the upper Eocene phosphate‐rich glauconitic sandstones of the overlying Hamra Formation may record the initial stages of the palaeoclimatic transition from greenhouse to icehouse conditions.
A novel HLA‐B allele, HLA‐B*44:184, identified by super high‐resolution single‐molecule sequence‐based typing in a Japanese individual
Authors: Wada A. , Shiina T. , Michino J. , Yasumura S. , Sugiyama T.
Published: January 2014

The novel allele HLA‐B*44:184 differs from HLA‐B*44:77 by three non‐synonymous amino acid exchanges, T94I, L95I and S97R.
Full‐length sequence of a novel null allele HLA‐A*11:69N identified in a Chinese individual
Authors: Gao S.‐Q. , Xu Y.‐P. , Deng Zh.‐H.
Published: January 2014

We describe here a novel null allele of human leukocyte antigen gene, A*11:69N, which was initially found in a blood donor from China.
Effect of azithromycin mass drug administration for trachoma on spleen rates in Gambian children
Authors: Hart John D. , Edwards Tansy , Burr Sarah E. , Harding‐Esch Emma M. , Takaoka Kensuke , Holland Martin J. , Sillah Ansumana , Mabey David C. W. , Bailey Robin L.
Published: January 2014

Objective

To assess the effect of azithromycin mass drug administration regimens on spleen rates in children aged 0–5 years.

Methods

Clinical assessment of spleen size was carried out during a cluster‐randomised trial of azithromycin mass treatment for trachoma elimination in The Gambia. Twenty‐four communities received three annual mass treatments with azithromycin, and 24 communities received treatment at baseline only.

Results

At the 30‐month follow‐up, 3646 children aged 0–5 years had spleen examination and measurement. Palpable splenomegaly was significantly lower in annually treated vs. baseline‐only treatment communities and in treated vs. untreated children at 24 months in the annual treatment arm.

Conclusion

The results suggest an effect of azithromycin on spleen rates at the individual level and are most plausibly due to the antimalarial effects of azithromycin.
Times Semi-Passive RFID Tags with Double Loop Antennas Arranged as a Shifted Gate Stability Optimization
Authors: Aluf Ofer
Published: January 2014

In this article, Very Crucial subject discussed in Semi-Passive RFID TAGs system stability. Semi-Passive TAGs with double loop antennas arranged as a shifted gate system stability optimization under delayed electromagnetic interferences. The double loop antenna is employed due to the fact that this antenna consists of two parallel loops; i.e., primary and secondary loops. We define Vi1(t) and Vi2(t) as the voltages in time on double loop antennas. Vi1(t) is the voltage in time on the primary loop and Vi2(t) is the voltage in time on the secondary loop. The index (i) stand for the first gate (i=1) and second gate (i=2). Due to electromagnetic interferences there are different in time delays respect to gate antenna's first and second loop voltages and voltages derivatives. The delayed voltages are Vi1(t-τ1) and Vi2(t-τ2) respectively (τ1≠ τ2) and delayed voltages derivatives are dVi1(t-Δ1)/dt, dVi2(t-Δ2)/dt respectively.
Practical Thermal Evaluation Methods for HAC Fire Analysis in Type B Radioactive Material (RAM) Packages
Authors: Gupta Narendra K. , Hensel Stephen J. , Abramczyk Glenn
Published: January 2014

Title 10 of the United States Code of Federal Regulations Part 71 for the Nuclear Regulatory Commission (10 CFR Part 71.73[1]) requires that Type B radioactive material (RAM) packages satisfy certain Hypothetical Accident Conditions (HAC) thermal design requirements to ensure package safety during accidental fire conditions. Compliance with thermal design requirements can be met by prototype tests, analyses only or a combination of tests and analyses. Normally, it is impractical to meet all the HAC using tests only and the analytical methods are too complex due to the multi-physics non-linear nature of the fire event. Therefore, a combination of tests and thermal analyses methods using commercial heat transfer software are used to meet the necessary design requirements. The authors, along with his other colleagues at Savannah River National Laboratory in Aiken, SC, USA, have successfully used this ‘tests and analyses’ approach in the design and certification of several United States’ DOE/NNSA certified packages, e.g. 9975, 9977, 9978, 9979, H1700, and Bulk Tritium Shipping Package (BTSP). This paper will describe these methods and it is hoped that the RAM Type B package designers and analysts can use them for their applications.
Further Insights on J-R Curve Behavior in Pipeline Steels Using Low Constraint Fracture Specimens
Authors: Sarzosa Diego F. B. , Ruggieri Claudio
Published: January 2014

This work addresses a two-parameter description of crack-tip fields in bend and tensile fracture specimens incorporating the evolution of near-tip stresses following stable crack growth with increased values of the J-integral. The primary objective is to examine the potential coupled effects of geometry and ductile tearing on crack-tip constraint as characterized by the J-Q theory which enables more accurate correlations of crack growth resistance behavior in conventional fracture specimens. Plane-strain, finite element computations including stationary and growth analyses are described for SE(B) and clamped SE(T) specimens having different notch depth to specimen width ratio in the range 0.2≤ a/W≤0.5. A computational cell methodology to model Mode I crack extension in ductile materials is utilized to describe the evolution of J with Δa for the fracture specimens. Laboratory testing of an API 5L X70 steel using deeply cracked C(T) specimens is used to measure the crack growth resistance curve for the material and to calibrate the cell parameters. The present results provide additional understanding of the effects of constraint on crack growth which contributes to further evaluation of crack growth resistance properties of pipeline steels using SE (T) and SE(B) specimens.
Ductile Failure Modelling of Expanded Aluminium Tubes With Embedded Circular Holes
Authors: Barsoum Imad , Khan Farhat , Seibi Abdennour , Molki Arman
Published: January 2014

A common technology used for well completion in the oil and gas industry is the solid expandable tubular technology, where a metal pipe is expanded radially towards the well bore. A challenge in this technology is to assess the mechanical integrity of the pipes during the expansion process. In this paper the ductile failure behavior of mechanically expanded aluminum tubes was studied experimentally and numerically. The expansion of the tubes was performed mechanically by using a conical mandrel with the objective to study the failure mode that governs the expansion process of this material. To localize the failure the tubes were drilled with circular holes. The fractured surfaces of failed expanded tubes were examined and revealed a flat ductile dimple rupture characteristic. A finite element model, which is based on continuum damage mechanics, is developed to mimic the experiments. The model also predicts ductile crack propagation and failure in the expanded tubes with embedded holes very well making it a suitable tool for studying the tubular expansion process and for optimizing the expansion tools used in this process.
Stress and Strain Fields in the Hemispherical Head of an FCC Regenerator During the Lifting Maneuver in Cyclone Replacement
Authors: Garrido Erik , Casanova Euro
Published: January 2014

The Oil and Gas industry is constantly seeking for improvements in the design of mechanical equipment. Each refining process is the subject of continuous research, which is frequently addressed in the revisions of the corresponding standard. Nevertheless, particular technologies such as the Fluid Catalytic Cracking Units (FCCU) are not governed by any International Standard but by designs developed and patented by specialized licensors. The implementation of new designs requires special studies of the original equipment in order to assess the feasibility of the related works and the required provisions to accomplish the revamp. This work studies the stress and displacement fields occurring in the hemispherical head of an FCC regenerator during the lifting maneuver for a typical cyclone replacement.

A parametric finite element model was developed and stress and total displacement charts are presented as a function of diameters and thicknesses of hemispherical heads commonly found in the industry. Sensitivity analyses are presented with respect to a variation of ±15% of the applied loads and the size of the plenum chamber. Therefore, the results shown in this work present a reference framework for the replacement of cyclones in FCC regenerators when removing their hemispherical heads.
Minimum Fatigue Pre-Crack Extension for Fracture Testing
Authors: Walters Carey L. , Voormeeren Lars O.
Published: January 2014

The minimum pre-crack necessary to achieve an accurate measurement of the J-integral is examined with the use of elastic-plastic finite element analysis. This minimum pre-crack is shorter than what is specified in fracture codes ASTM E1820 and BS 7448. A variety of steel properties are considered, but the focus is on S690 grade steel. Testing a SENB specimen from S690 steel with a notch width of 0.5 mm and a minimum pre-crack length of 0.5 mm can result in the same J integral as the same specimen with a much longer pre-crack. Finally, it is shown that a surface pre-crack length of 0.5 is practically achievable.
Prediction of the Inner Temperatures in a Duct Based on Outer Thermocouples Measurements
Authors: Gervais Stéphane , Girard Alexandre
Published: January 2014

Nuclear power plants (NPP) include connections of branches conveying fluids at different temperatures. Some thermohydraulics phenomena such as stratification may affect the inner wall of the ducts and lead to fatigue damage. They are then defined in a conservative way for fatigue evaluation. In order to improve the definitions of these phenomena EDF plans to install thermocouples rings on the outer surfaces of some ducts.

The aim of this article is to define a methodology to derive thermal loadings from outer measurements.

To estimate the temperature of the inner skin duct through measurements on the outer surface of the ducts, we propose to use optimal control (with quadratic cost functions) to compare the outer temperatures calculated with a finite element model and the measurements.

Different methods are investigated: first, a method based on Nelder-Mead algorithm [3] and second, an advanced method based on gradient computation.

The advantage of the latter is to explicitly compute the gradient and a Hessian approximation of the cost function with respect to the water temperatures, which is time saving for computation-wise. To enhance the robustness of the methodology, additional conditions on the regularity of the fluid temperature field are added.
Effect of Structural Dimensions on Strain Growth of Cylindrical Vessels
Authors: Dong Q. , Gu Y.
Published: January 2014

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the earlier stage. To further study the mechanism of strain growth, the effect of structural dimensions on strain growth of cylindrical vessels subjected to internal blast loading is thoroughly investigated in this paper. The dynamic response characteristics of eight cylindrical shells with different lengths and thicknesses are studied by finite element software LS-DYNA. It is shown that the structural dimension is a dominant influencing factor of strain growth.
Design Analysis and Qualification of Buried Metallic Pipe
Authors: Antaki George , Becht Charles , Shipley Michael
Published: January 2014

In this paper we review and compile the design equations for buried metallic pipe. The nomenclature is provided at the back of the paper, and is not repeated with each equation.

The methods and criteria presented here are applicable to safety-related, or non-safety-related, buried piping systems designed and qualified to ASME III Class 2 or 3, ASME B31.7 (Ref. 4), or ASME B31.1. As is always the case with safety-related piping systems, the engineer should verify the compatibility of the equations presented here with the licensing basis of the plant.

It is not our intent to introduce new methods or criteria in this paper. Instead, our objective is to compile existing theories, methods and criteria that are dispersed in several standards, publications, and textbooks, so as to provide a structured approach to the design process.
Effect of Pressure on Two-Phase Modeling for Viscous Potential Flow
Authors: Ahmadi Somayeh
Published: January 2014

In this study, the effect of pressure on the disturbed interface for two-phase stratified regime will be discussed. It is assumed that the two phases are in potential flow condition, a pressure correction algorithm for the two-fluid model is carefully implemented to minimize its effect on numerical stability. Numerical analysis is applied using the finite difference method. Actually pressure correction scheme is employed to solve the viscous potential flow model. It is designed to increase the computational stability when the flow is near the ill-posedness condition. The viscous potential flow theory fits the only pressure experimental data for air and water well.
Study on the Control of Displacement for Base Isolation Systems Utilizing High-Viscous Liquid (Effects of Eccentricity)
Authors: Ito Tomohiro , Nishimatsu Naoto , Shintani Atsuhiko , Nakagawa Chihiro
Published: January 2014

In Japan, ensuring the structural integrity of cask systems during seismic events is becoming increasingly important. Cask systems, which are free-standing cylindrical structures that contain spent fuel assemblies, are considered as sliding isolation systems. Thus far, analytical studies conducted by the authors have already indicated that cask systems subjected to strong seismic motions, undergo large sliding motions, and in the worst case, may collide with one another. Therefore, reducing the sliding motions of casks to avoid mutual collisions and consequent contamination of radioactive substances is critical.

To suppress sliding motions for very heavy free-standing structures such as cask systems, the authors proposed a sliding motion suppression system that uses high-viscous liquid and coaxial circular cylinders. This system is installed at the bottom end of the structure and the annular space is filled with a high-viscous liquid. A previous study showed that high-viscous liquid in annular spaces provides added damping effects of considerable magnitude, and thus allows the sliding motion to be suppressed.

In this study, the added damping effects of the annular space liquid are clarified using a fundamental testing device for various liquid viscosities, ratios of diameters for the inner and outer cylinders, and eccentricities of the inner cylinder. Moreover, shaking table tests are conducted to confirm that the added damping effects suppress excessive displacement.
Residual Stress Measurements and Modelling for Temper Bead Qualification
Authors: Ficquet Xavier , Robin Vincent , Kingston Ed , Courtin Stéphan , Yescas Miguel
Published: January 2014

This paper presents results from a programme of through thickness residual stress measurements and finite element analysis (FEA) modelling carried out on a temper bead mock-up. Emphasis is placed on results comparison rather than the measurement technique and procedure, which is well documented in the accompanying references. Temper bead welding processes have been developed to simulate the tempering effect of post-weld heat treatment and are used to repair reactor pressure vessel components to alleviate the need for further heat-treatment.

The Temper Bead Mock-up comprised of a rectangular block with dimension 960mm × 189mm × 124mm was manufactured from a ferritic steel forged block with an austenitic stainless steel buttering and a nickel alloy temper bead cladding. The temper bead and buttering surfaces were machined after welding. Biaxial residual stresses were measured at a number of locations using the standard Deep-Hole Drilling (DHD) and Incremental DHD (iDHD) techniques on the Temper Bead Mock-up and compared with FEA modelling results. An excellent correlation existed between the iDHD and the modelled results, and highlighted the need for the iDHD technique in order to account for plastic relaxation during the measurement process.

Maximum tensile residual stresses through the thickness were observed near the austenitic stainless steel surface at 298MPa. High compressive stresses were observed within the ferritic base plate beneath the bimetallic interface between austenitic and ferritic steels with peak stresses of −377MPa in the longitudinal direction.
ASME Section III Stress Analysis of a Heat Exchanger Tubesheet With a Misdrilled Hole and Irregular or Thin Ligaments
Authors: Gomez Enrique , Ruiz Roberto , Wilson Robert M. (Con)
Published: January 2014

A stress analysis is described for a nuclear steam generator tubesheet with a thin or irregular ligament associated with a mis-drilled hole using the rules of ASME B&PV Section III and Non-Mandatory Appendix A, Article A-8000 for Stresses in Perforated Flat Plates. The analysis demonstrates the proper application of the NB-3200 rules for this special application with discussion of the differences between an actual tube hole deviation from what is assumed in ASME Appendix A. This is a companion paper to “Technical Justification Supporting Operation with a Tube Installed in a Mis-Drilled Hole of a Steam Generator Tubesheet”.
A LEFM Based Study on the Interaction Between an Edge and an Embedded Parallel Crack
Authors: Ma Q. , Levy C. , Perl M.
Published: January 2014

Parallel cracks are often detected in components of various pressurized applications using non-destructive methods. For non-aligned parallel cracks, on-site service needs to decide whether they should be treated as coalesced or separate multiple cracks for Fitness-for-Service. Criteria and standards for the adjustment of multiple nonaligned cracks are very different from one another in existing resources. And those criteria and standards are often derived from on-site service experience without rigorous and systematic verification. Based on this observation, in this study the interaction between an edge and an embedded parallel crack is investigated to correlate criteria and standards from various resources in order to recommend the usage of those standards for the purpose of Fitness-for-service and to classify them as either conservative or non-conservative. If H and S represent the horizontal gap and vertical separation distance, respectively, between the cracks, and a2 is the length of the dominant crack, a parametric study of parallel crack separation distance and gap on the crack stress intensity factor has been undertaken. Stress intensity factors (SIFs) have been acquired for a wide range of the normalized gap of H/a2 = 0.4∼2 and the normalized separation distance of S/a2 = −0.5∼2 between the two parallel cracks based on the principle of linear elastic fracture mechanics (LEFM). This study indicates that certain existing standards/criteria provide results that are much more conservative than others while certain ones do not provide adequate information for application.
Comparison of the Limit Loads Between Defected Pressure Pipes With an Internal Pit and an External Pit at High Temperature
Authors: Zhou Changyu , Wang Bo , Sun Zhigang , Xue Jilin , He Xiaohua
Published: January 2014

High temperature pressure pipes are widely used in power stations, nuclear power plants, and petroleum refinery, which always bear combined effects of high temperature, high pressure, and corrosive media, so the local pits are the most common volume defects in pressure pipe. Due to various reasons, the defects usually appear on the internal or external wall of pipe. In this paper, the dimensions of a defect were characterized as three dimensionless factors: relative depth, relative gradient and relative length. The main objects of study were the pipe with an internal pit and pipe with an external pit. Orthogonal array testing of three factors at four different levels was applied to analyze the sequence of the influence of three parameters. In present study, when the maximum principal strain nearby the location of the defects reaches 2%, the corresponding load is defined as the limit load, which is classified as two kinds of load type: limit pressure and limit bending moment. According to this strain criterion and isochronous stress strain data of P91 steel, the limit load of high temperature pipe with a local pit was determined by using ABAQUS. And in the same load condition of the pipe with the same dimensionless factors, the limit load of the internal defected pipe was compared with that of the external defected pipe. The results of this study can provide a reference for safety assessment and structural integrity analysis of high temperature creep pressure pipe with pit defects.
The Delivery of Technical Training Within the European Style Project
Authors: Toft Adam , Sharples John
Published: January 2014

The STYLE project considers structural integrity for lifetime management of non-reactor pressure vessel components of nuclear power plant. The project is funded under the seventh European Commission framework programme. A broad objective of the project is to assess, optimise and develop application of advanced tools for structural integrity assessment of reactor coolant pressure boundary components other than the reactor pressure vessel.

One aspect of the STYLE project is intended to address the issue of succession planning within the European nuclear industry. With many key technical experts now approaching retirement it is essential to progress the technical expertise of those at an earlier stage of their career in the industry.

The paper describes how technical training has been delivered as an integral part of the STYLE project to support retention of the current level of technical capability in future.

Diverse aspects of training are described. These include participation in experimental work, numerical modelling and simulation, application of engineering assessment procedures, leak-before-break, probabilistic fracture mechanics and materials behaviour. An illustrative case study is described, in which trainees received practical instruction in the essential steps for technical justification of a leak-before-break argument.
Development of Non-Idealized Surface to Through-Wall Crack Transition Model
Authors: Shim Do-Jun , Kurth Robert , Rudland David
Published: January 2014

Recent work by the authors have shown that a subcritical surface crack (SC) can transition to a through-wall crack (TWC) with significant differences between the inner diameter (ID) and outer diameter (OD) crack lengths. In the current versions of the xLPR code (Ver. 1.0), an idealized through-wall crack (which has the same area as the final surface crack) is formed once the surface crack penetrates the wall thickness. This type of crack transition was selected since no general stress intensity factor (K) and crack-opening displacement (COD) solutions were available for crack shapes that would form during the transitioning stages, i.e., non-idealized through-wall cracks. However, it has been demonstrated that this idealized through-wall crack may result in an overestimate of the leak rate. Thus, it is necessary to further investigate and develop a model that can handle the surface crack to through-wall crack transition.

In this paper, a surface to through-wall crack transition model was proposed using existing K and COD solutions for non-idealized through-wall cracks. This model includes a criterion for transitioning the final surface crack to the initial non-idealized through-wall crack which determines when the transition should occur (based on surface crack depth) and determines the two crack lengths (at ID and OD surfaces) of the initial non-idealized through-wall crack. Furthermore non-idealized through-wall crack growth can be conducted using the proposed model. Example results (crack shape and COD) obtained from the proposed model were compared to those obtained from the natural crack growth simulations for a circumferential crack. Results presented in this paper demonstrated the applicability of the proposed model for simulating crack transition. Limitation of the present model and plans for future work are also discussed in the paper.
Experimental Evaluation of Fatigue Life of Coke Drum Materials With Weld Sections
Authors: Chen Jie , Yamamoto Toshiya , Xia Zihui , Esaki Keiji
Published: January 2014

Coke drums are vertical pressure vessels used in the delayed coking process in petroleum refineries. Significant temperature variation during the delayed coking process causes damage in coke drums in the form of bulging and cracking. It was also observed that most cracks were near or within the weld seams. In order to better understand fatigue damage mechanisms of the coke drum materials with their weld sections, an experimental investigation of fatigue lives of these materials are carried out. It is a common consideration that the yield strength of the weld should be within a close percentage to that of base material in order to keep strength uniformity throughout the drum shell sections. However, this effect of the yield strength matching on the shell durability has not yet clarified quantitatively. From this point of view, two different types of specimens have been designed and manufactured: base material only, base with base weld. In addition, three groups of base with weld materials with different ratios of weld to base yield strengths are prepared. Low cycle fatigue tests at elevated temperature of 250°C are carried out on the above specimens. Through study on the recorded stress-strain hysteresis loops and observation on the fracture surfaces, damage mechanisms of different types of specimens are analyzed. Their strain range–fatigue life curves are also compared. Furthermore, finite element analyses based on the actual specimens’ geometries and properties are conducted to help in understanding the experimental observations. This experimental evaluation of fatigue life of coke drum materials with welds may provide a good reference for better design of coke drums in the future.
The Consequences of Macroscopic Segregation on the Transformation Behaviour of a Pressure-Vessel Steel
Authors: Pickering Ed , Bhadeshia Harry
Published: January 2014

It is important that the material used to produce high-integrity pressure vessels has homogeneous properties which are reproducible and within specification. Most heavy pressure vessels comprise large forgings derived from ingots, and are consequently affected by the chemical segregation that occurs during ingot casting. Of particular concern are the compositional variations that arise from macrosegregation, such as the channels of enriched material commonly referred to as A-segregates. By causing corresponding variations in microstructure, the segregation may be detrimental to mechanical properties. Given the scale of the pressure vessel casting, the segregation cannot be removed by practically feasible heat treatments.

Here we describe an investigation on the consequences of macrosegregation on the development of microstructure in a pressure-vessel steel, SA508 Grade 3. It is demonstrated that the kinetics of transformation are sensitive to the segregation, resulting in a dramatic spatial variations in microstructure. It is likely therefore that some of the scatter in mechanical properties as observed for such pressure vessels can be attributed to macroscopic casting-induced chemical segregation.
Development and Assessment of Ultrasonic Inspection System for Polyethylene Pipes
Authors: Spicer Malcolm , Troughton Mike , Hagglund Fredrik
Published: January 2014

The American Society of Mechanical Engineers (ASME) is revising the published Code Case (N-755) for the use of polyethylene (PE) in nuclear power plant buried pipe systems. However, the United States Nuclear Regulatory Commission (NRC) has not approved this Code Case due to a number of concerns; one of which is the lack of validated non-destructive examination (NDE) techniques for inspecting welded joints in PE pipes. This paper describes the development of an ultrasonic phased array system and procedures for the inspection of welded joints in PE pipes of diameters between 125 and 1000mm. The system includes hardware and software which has been designed specifically for inspecting PE pipe joints. The system has been assessed by a number of organizations and the results of these trials will be presented. Alongside the development of the inspection system, a major program of work has been carried out to develop acceptance criteria for flaws in PE pipe welds. The types of flaws investigated included particulate contamination, planar flaws and cold fusions. The critical flaw sizes and contamination levels were determined based on both long-term and short-term testing of welded joints in PE pipes.
In Vitro Study of the Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve
Authors: Barannyk Oleksandr , Karri Satya , Oshkai Peter
Published: January 2014

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted to the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases, classified into two clinical categories, were correlated with the corresponding changes of aortic root geometry. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.
Response of Piping Tees to Propagating Detonations
Authors: Ligon Thomas C. , Gross David J. , Shepherd Joseph E.
Published: January 2014

This paper reports the results of experiments and finite element simulations on the structural response of piping systems to internal detonation loading. Specifically, the work described in this paper focuses on the forces that are produced at tee-junctions that lead to axial and bending structural responses of the piping system.

Detonation experiments were conducted in a 2-in. (50 mm) diameter schedule 40 piping system that was fabricated using 304 stainless steel and welded to ASME B31.3 standards. The 4.1 m (162-in.) long piping system included one tee and was supported using custom brackets and cantilever beams fastened to steel plates that were bolted to the laboratory walls. Nearly-ideal detonations were used in a 30/70 H2-N2O mixture at 1 atm initial pressure and 300 K. Pressure and hoop, axial, and support strains were measured using a high-speed (1 MHz) digital data acquisition system and calibrated signal conditioners.

It was concluded that detonations propagate through the run of a 90° tee with relatively little disturbance in either direction. The detonation load increases by approximately a factor of 2 when the detonation enters through the branch. The deflections of the cantilever beam supports and the hoop and axial pipe strains could be adequately predicted by finite element simulations. The support loads are adequately predicted as long as the supports are constrained to the piping.

This paper shows that with relatively simple models, quantitative predictions of tee forces can be made for the purposes of design or safety analysis of piping systems subject to internal detonations.
Damage-Based Modeling and Analysis of Reactor Vessels With Numerous Base Metal Ultrasonic Indications
Authors: Rashid Joseph Y. R. , Hardin Timothy , Rashid Mark M. , Dunham Robert S. , Kubischta Keith
Published: January 2014

The numerous indications recently found by UT-inspection in the reactor pressure vessel shell forgings at two Belgian nuclear power plants have raised some concerns about the effects of such indications on the vessel integrity and fitness for continued service. The UT indications have been attributed to hydrogen flaking, and preliminary estimates give a density of ∼40 indications per liter, with diameter of about 10–14 mm, oriented at a shallow ∼10° angle to the vessel inner surface. This type of high-density indications would not be characterized as geometric flaws with well defined crack-tip geometry that permits high-fidelity application of traditional fracture mechanics methods. An alternative analysis approach, with higher fidelity simulation of this type of “distributed discontinuities”, is proposed, as described in this paper.

From a behavioral standpoint, the UT indications at Doel 3 and Tihange 2 represent material discontinuities whose mechanical effect can be evaluated using a damage-mechanics-based constitutive model. Previously, a special multiphase damage model was developed for cladding with zirconium hydrides, of similar morphology to the Doel 3 indications, in which the metal matrix and the hydride platelets are treated as separate material phases interacting at their interfaces with appropriate constraint conditions between them to ensure strain and stress compatibility. The hydride precipitates are represented as a brittle material and the metal matrix is modeled as a ductile elastic-plastic material. This damage model was implemented in a finite element computer program, and was validated using ring-tension and ring-compression tests of cladding specimens with various hydride morphologies. The model was able to predict specimens complete stress-strain curves and failure states with very high accuracy.

The above described damage model is adapted to the high-density UT indications, morphology and distribution similar to the conditions of the Doel 3 vessel. The “hydrogen flakes” are characterized in the model as distributed damage of known orientation and volume fraction. A vessel of typical geometry and radiation-dependent mechanical properties is analyzed for various values of volume fraction of hydrogen flakes, and considering a transient loading scenario that conservatively simulates pressurized thermal shock. Interlinking of the “hydrogen flakes” and propagation of damage through the wall under the specified loading condition are part of the model’s capability of directly predicting whether or not vessel failure will occur. Thus, vessel susceptibility to failure and failure margin are judged by the degree of damage propagation through the wall.