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Particle size control in mineral processing is typically achieved using an index characterising the whole distribution, e.g. the sieve opening through which a given mass fraction of the population would pass. Although mineral liberation is the goal of size reduction, its use for monitoring and process control applications is not reported because its online measuring is currently not possible. This paper proposes to address this issue using a mineral liberation distribution estimator consisting in two models. The first one uses a polynomial expression to relate the size-by-size mineralogical distribution of every mineral species to that of the ore. The second model relies on a beta distribution function to sort the masses in every size fraction into liberation classes. The characteristic constants of the beta function are parameterised with the properties of the ore. Results demonstrate that the liberation estimator can represent liberation distributions of both fresh and processed comminution products.

Management of operating nuclear power plants greatly relies on structural integrity assessments for safety critical pressure vessels and piping components. In the present work, residual stress profiles of girth welded austenitic stainless steel pipes are characterised using an artificial neural network approach. The network has been trained using residual stress data acquired from experimental measurements found in literature. The neural network predictions are validated using experimental measurements undertaken using neutron diffraction and the contour method. The approach can be used to predict through-wall distribution of residual stresses over a wide range of pipe geometries and welding parameters thereby finding potential applications in structural integrity assessment of austenitic stainless steel girth welds.

A series of engineering-scale multi-pass pipe girth weld mock-ups were manufactured using conventional manual metal arc techniques from Esshete 1250 austenitic steel. They were characterised in detail, in order to provide validation benchmarks for finite element prediction of weld residual stresses. The fabrication sequence comprised initial solution heat treatment and quenching, manufacture of five closely spaced girth welds in a single assembly, and then separation into five individual weldments. Detailed welding records were kept, to allow subsequent calibration of weld heat source models. Residual stresses were measured using diverse methods (incremental deep hole drilling and the contour method), in both the as-welded condition and after thermal ageing at 650 °C. The measurements showed good agreement, providing reliable validation targets for predicted residual stresses in both states. Detailed mechanical property characterisation was performed on both parent material and weld metal, comprising monotonic and isothermal cyclic testing over a range of temperatures from ambient up to 1000 °C. The test data were used to derive a range of Lemaitre-Chaboche mixed isotropic-kinematic model parameter sets for use in finite element simulation. These welds and their supporting characterisation comprise a reliable benchmark for weld residual stress simulation in an engineering-scale weldment.

Application of the contour method for the measurement of weld residual stresses (WRS) is prone to inaccuracy due to plastic deformation resulting from the redistribution of typically high (close to yield) WRS during the cutting process. The current work, seeks ways to mitigate cutting-induced plasticity by controlling stress redistribution through optimisation of the contour cutting configuration. The idea of using a stress-informed fracture mechanics approach to find the optimal cutting configuration is introduced. The level of plasticity associated with different cutting configurations is then assessed, allowing control of the location and magnitude of cutting-induced plasticity to occur during the cutting process. A conventional edge-crack cutting configuration is compared with a proposed double-embedded cutting configuration by measuring the longitudinal WRS in two three-pass slot weld specimens (NeT TG4) produced using identical weld procedures. The experimental results show that a novel double-embedded cutting configuration leads to greater accuracy in WRS measurements relative to conventional edge-crack cutting configurations at the expense of higher levels of plasticity being introduced local to small ligaments.

Novel semi-conductive fibres from multiwalled carbon nanotubes (MWCNT) based-polyethersulfone (PES) have been produced by wet spinning insight of incorporation in composite matrix. N-methyl-2-pyrrolidone (NMP) was chosen as dispersing medium for MWCNT by sonication and as solvent for PES. MWCNT reinforced-PES fibres were spun into water coagulation bath with an observed instantaneous liquid-liquid demixing. After washing and drying steps, fibres are either directly characterized or annealed at 250 °C during 15 min and 24 h prior to characterization. Scanning electron microscope (SEM) micrographs performed in each configuration disclose presence of macrovoids, pores and empty spaces inside fibres before thermal annealing whereas after thermal annealing, fibres display a cohesive and continuous morphology. A significant mechanical properties improvement of the wet-spun fibres is noticed by rising annealing time. Transmission electron microscope (TEM) investigations have also been carried out and reveal a two phases microstructure in unannealed fibres with a separation between a PES-rich continuous phase and NMP-rich nodules containing exclusively MWCNT. TEM images suggest also thermal annealing process allows solvent evaporation, MWCNT aggregation and a conductive nanofillers network formation in PES nanocomposite fibres. Electrical measurement in unannealed fibres indicate a deficiency of conductive character between 0.25 and 2 wt.% MWCNT whereas a lowering electrical percolation threshold is achieved in fibres by increasing annealing time, around 1.5 and 1 wt.% MWCNT for respectively a 15 min and 24 h thermal annealing. Influence of MWCNT sonication duration on electrical conductivity is also examined showing a gradually reduction of fibres' electrical conductivity by dispersion time increasing until losing their semi-conductive state. A dispersion analysis let suppose that a whole MWCNT agglomerates network is split in smaller but denser clusters which are dispersed and taken away from each other during sonication, which causes the conductive path rupture.

The data included in this article comprise raw and processed images of fixed cells at baseline and subjected to various experimental perturbations. This dataset includes images of HUVEC cells fixed and subsequently incubated at either 37°C or room temperature, primary rat vascular smooth muscle cells exposed to 25mM glucose, and SH-SY5Y neurons exposed to hydrogen peroxide. Raw images appear exactly as they were captured on the microscope, while processed images show the binarization provided by software used for measurements of mitochondrial morphology. For in-depth discussion of the experiments and computational methods pertaining to this data, please refer to the corresponding research article titled “Fully automated software for quantitative measurements of mitochondrial morphology” (McClatchey et al., in press) [1].

Economic and safe management of nuclear plant components relies on accurate prediction of welding-induced residual stresses. In this study, the distribution of residual stress through the thickness of austenitic stainless steel welds has been measured using neutron diffraction and the contour method. The measured data are used to validate residual stress profiles predicted by an artificial neural network approach (ANN) as a function of welding heat input and geometry. Maximum tensile stresses with magnitude close to the yield strength of the material were observed near the weld cap in both axial and hoop direction of the welds. Significant scatter of more than 200 MPa was found within the residual stress measurements at the weld center line and are associated with the geometry and welding conditions of individual weld passes. The ANN prediction is developed in an attempt to effectively quantify this phenomenon of ‘innate scatter’ and to learn the non-linear patterns in the weld residual stress profiles. Furthermore, the efficacy of the ANN method for defining through-thickness residual stress profiles in welds for application in structural integrity assessments is evaluated.

International audience; Allergic rhinitis often impairs social life and performance. The aim of this cross-sectional study was to use cell phone data to assess the impact on work productivity of uncontrolled rhinitis assessed by visual analogue scale (VAS). A mobile phone app (Allergy Diary, Google Play Store and Apple App Store) collects data from daily visual analogue scales (VAS) for overall allergic symptoms (VAS-global measured), nasal (VAS-nasal), ocular (VAS-ocular) and asthma symptoms (VAS-asthma) as well as work (VAS-work). A combined nasal-ocular score is calculated. The Allergy Diary is available in 21 countries. The app includes the Work Productivity and Activity Impairment Allergic Specific Questionnaire (WPAI:AS) in six EU countries. All consecutive users who completed the VAS-work from 1 June to 31 October 2016 were included in the study. A total of 1136 users filled in 5818 days of VAS-work. Symptoms of allergic rhinitis were controlled (VAS-global 50). There was a significant correlation between VAS-global calculated and VAS-work (Rho=0.83, P

A Good Practice is a practice that works well, produces good results, and is recommended as a model. MACVIA-ARIA Sentinel Network (MASK), the new Allergic Rhinitis and its Impact on Asthma (ARIA) initiative, is an example of a Good Practice focusing on the implementation of multi-sectoral care pathways using emerging technologies with real life data in rhinitis and asthma multi-morbidity. The European Union Joint Action on Chronic Diseases and Promoting Healthy Ageing across the Life Cycle (JA-CHRODIS) has developed a checklist of 28 items for the evaluation of Good Practices. SUNFRAIL (Reference Sites Network for Prevention and Care of Frailty and Chronic Conditions in community dwelling persons of EU Countries), a European Union project, assessed whether MASK is in line with the 28 items of JA-CHRODIS. A short summary was proposed for each item and 18 experts, all members of ARIA and SUNFRAIL from 12 countries, assessed the 28 items using a Survey Monkey-based questionnaire. A visual analogue scale (VAS) from 0 (strongly disagree) to 100 (strongly agree) was used. Agreement equal or over 75% was observed for 14 items (50%). MASK is following the JA-CHRODIS recommendations for the evaluation of Good Practices., MACVIA-France., info:eu-repo/semantics/publishedVersion

The purpose of this paper is to demonstrate a) application of the contour method in measuring residual stresses in large complex geometries such as a welded pipe, b) the power of combining the contour measurement approach with other measurement methods in order to map multiple components of stress tensor in structures, c) the capability of the contour method for characterising residual stresses where there are steep gradients of stress, for example in an electron beam welded plate, and d) mapping multiple components of residual stress in thick structures using multiple cuts.

Residual stresses in 9 mm thick ASTM A387 Grade 91 steel plates, joined using constant power (8 kW) low and high heat input laser welding processes, are characterised using neutron diffraction. The measured longitudinal and normal components of residual stress show a bimodal distribution across the welded joint with a low tensile or compressive trough at the weld centre flanked by high magnitude tensile peaks in parent metal adjacent to the heat affected zone boundaries. The width of the central trough and spread of the outboard tensile zones are significantly greater for the high heat input weld. In both cases, the stress distributions can be explained by the strains associated with the austenite to martensite solid-state transformation as the joint cools after welding.

This paper describes the characterisation of residual stress in electron beam welded P91 ferritic–martensitic steel plates (9 mm thick) by neutron diffraction and contour measurement methods. The novelty of the work lies in revealing the residual stress profile at a fine length scale associated with a ∼1 mm wide fusion zone. A characteristic ‘M’ shaped distribution of stresses across the weld line is observed with high tensile peaks situated just beyond the heat affected zone/parent material boundary. Measured stresses close to the weld centreline are significantly less tensile than the adjacent peaks owing to martensitic phase transformation during cool down of the weld region. The effect of applying a second smoothing weld pass is shown to be undesirable from a residual stress standpoint because it increases the tensile magnitude and spread of residual stress. The results are suitable for validating finite element predictions of residual stress in electron beam welds made from ferritic–martensit...

The multiple cut contour method is applied to map longitudinal and transverse components of residual stress in two nominally identical 50 mm thick electron beam welded Ti-6Al-4V alloy plates, one in the as-welded condition and a second welded plate in a post weld heat treated (PWHT) condition. The accuracy and resolution of the contour method results are directly linked to the quality of the electro-discharge machining cut made. Two symmetric surface contour artefacts associated with cutting titanium, surface bowing and a flared edge, are identified and their influence on residual stresses calculated by the contour method is quantified. The former artefact is controlled by undertaking a series of cutting trials with reduced power settings to find optimal cutting conditions. The latter is mitigated by attaching 5 mm thick sacrificial plates to the wire exit side of the test specimen. The low level of noise in the measured stress profiles for both the as-welded and PWHT plates demonstrates the importance of controlling the quality of a contour cut and the added value of undertaking cutting trials.

Measurements of stress–strain properties and residual stress in purpose-designed one and three-pass groove-weld specimens are used to optimise a mixed hardening constitutive model for simulating residual stresses in austenitic Type 316 stainless steel weldments. It is demonstrated that isotropic hardening over-predicts the tensile magnitude of welding residual stress in the benchmark specimens, while pure kinematic hardening gives an under-prediction of longitudinal stresses in parent material close to the weld. The most accurate predictions are those based on optimised mixed isotropic–kinematic formulations combined with a multi-pass moving heat source welding analysis.

In this study the residual stresses in a pipe girth weld in a ferritic-martensitic power plant steel were measured by neutron diffraction and compared with the corresponding metallurgical zones in the weld region. It was found that, in both the as-welded and post-weld heat treated condition, the highest tensile stresses resided near the outer boundary of the heat-affected zone (HAZ), and towards the weld root region. Substantial tensile direct and hydrostatic stresses existed across the HAZ, including the fine-grained and intercritically annealed regions, where premature type IV creep failures manifest in 9–12 Cr steel welds. Compressive stresses were found in the weld metal coinciding with the last weld bead to be deposited. Constrained cooling tests on test coupons illustrated that these compressive stresses can be explained in terms of the influence that solid-state phase transformations have on the accumulation of stress in welds.

The implementation of the TDCR method (Triple to Double Coincidence Ratio) is based on a liquid scintillation system which comprises three photomultipliers; at LNHB, this counter can also be used in the beta-channel of a 4pi(LS)beta-gamma coincidence counting equipment. It is generally considered that the gamma-sensitivity of the liquid scintillation detector comes from the interaction of the gamma-photons in the scintillation cocktail but when introducing solid gamma-ray emitting sources instead of the scintillation vial, light emitted by the surrounding of the counter is observed. The explanation proposed in this article is that this effect comes from the emission of Cherenkov photons induced by Compton diffusion in the photomultiplier windows. In order to support this assertion, the creation and the propagation of Cherenkov photons inside the TDCR counter is simulated using the Monte Carlo code GEANT4. Stochastic calculations of double coincidences confirm the hypothesis of Cherenkov light produced in the photomultiplier windows.

Experimental, finite element analysis and statistical studies of residual stresses in edge welded type 316H stainless steel beams are presented. The experimental stress measurements were previously performed by different laboratories using neutron and synchrotron X-ray diffraction. An analytical model to describe the magnitude and distribution of the residual stresses is presented. Results from finite element analyses are also provided. It is found that there is general agreement between the trends in the residual stresses derived from analysis and measurement. However, the scatter in results is substantial and a statistical framework for treating residual stresses using Bayesian statistics based on experimental and simulation results is described. The Bayesian analytical approach that uses the analytical model as a reference permits the model to be applied to circumstances outside the experimental conditions.

Neutron diffraction has been used to investigate the weld residual stresses and the intergranular residual strains in butt-welded 316H pipes. Measurements have been made on pipes subjected to varying degrees of plastic pre-straining before welding, in order to assess the effects of plastic strain on the weld residual stresses and the intergranular strains in the material. The intergranular strains following plastic deformation will also be affected by the annealing effect of the welding. Pipes were initially prepared with plastic strain of 0, 10, 15, 20 and 25% plastic deformation. Thereafter, the pipes were cut in half and welded with a circumferential butt-weld. Bar specimens were extracted from the remote end of the 0, 10, 15, 20 and 25% pre-strained and welded pipes. Cross-weld bar specimens were also machined from the 0 and 20% pre-strained and welded pipes. Neutron diffraction measurements were made at ENGIN-X, ISIS and FRM-II, Munich. The aim of this paper is to evaluate the intergranular strains developed after pre-straining from measurements made in remote bar specimens from the remote-end of the pipes. The annealing effect of the welding cycle on the intergranular strains is also studied, with measurements done at several points on cross-weld bar specimens, obtaining the strain response of different hkl lattice planes. The results show that the {200} and {220} planes are at the extremes of response during loading. Furthermore, the welding thermal cycling relaxed the intergranular strains from the prior plastic deformation.

Dissimilar metal welds are often required in nuclear power plants to join components made from austenitic steels to those from ferritic steels, particularly in fast breeder reactor plants, in order to join the intermediate heat exchanger to the steam generator. The process of welding alters the microstructure of the base materials and causes residual stresses to form, both because of the change in the microstructure and the differing thermal histories in various regions. Postweld heat treatment (PWHT) is required to relieve the residual stresses and achieve preferable microstructural gradients across the weld joint. Therefore, in order to arrive at the optimal PWHT process, it is necessary to investigate the effects of heat treatment on the joint integrity, microstructure, and residual stress relaxation in the welds. To investigate the effect of PWHT on the residual stress relaxation and corresponding alteration of microstructure across a welded joint, a dissimilar weld between modified 9Cr-1Mo steel and austenitic stainless steel AISI 316LN was made using autogenous electron beam welding. To achieve this, the welding process was first modeled numerically using finite element analysis, and the residual stress predictions were validated by experimental investigation using neutron diffraction. The validated model was then used to study the residual stress relaxation through the simulation of PWHT. The predicted stress relaxation was compared with contour method measurement of residual stresses in the actual welded plate subjected to PWHT. The results indicate that, although somerelaxation of residual stresses occurred during PWHT, there is still a significant portion of highly localized residual stresses left in the specimen.

Fracture mechanics based structural integrity assessments of pressure vessels and piping are widely used to support the economic and safe management of operating engineering plant. Assessments of defects at weldments can be highly sensitive to the through-thickness distribution of residual stress assumed in the fracture calculations. Increasingly, finite element modelling approaches are applied to predict residual stress in engineering structures arising from the welding process. However, such methods are complex and require analysts to make many assumptions and approximations. Guidelines covering the calculation of residual stresses in weldments are being prepared for inclusion in the R6 defect assessment procedure and will be accompanied by a series of validation benchmarks. The benchmarks will allow analysts to evaluate and improve the accuracy of weld modelling approaches and assess their suitability for use in fracture assessments. The first part of this paper presents an austenitic stainless steel bead-on-plate weldment validation benchmark based on the extensive round robin measurements performed by members of the European NeT project. The benchmark defines thermal and residual stress performance targets against which a weld simulation approach can be evaluated. Guidance is also provided on how to validate predicted residual stress profiles for use in a high integrity fracture assessment. The second part of this paper provides a commentary on how the weld simulation accuracy and performance targets have been established.

The distribution of residual stress in three orthogonal directions has been measured within a Type 316L austenitic stainless steel bead-on-plate weld specimen. Neutron diffraction was employed using the ENGIN-X instrument, located at the ISIS spallation facility of the Rutherford Appleton Laboratory, UK. A stress-free lattice parameter reference value was determined from a small cube, extracted from a far corner of the plate. A high magnitude of tensile residual stress was found along the weld bead in the longitudinal and transverse directions. The distributions of stress along through-thickness lines at the weld bead nominal start and stop locations and at the mid-length position showed an almost identical stress variation. However, a map of measured residual strain in the transverse direction beneath the weld bead revealed a concentration of strain located several millimetres before the nominal weld stop position where through-wall stress profiles were measured.

Until recently residual stresses have been included in structural integrity assessments of nuclear pressure vessels and piping in a very primitive manner due to the lack of reliable residual stress measurement or prediction tools. This situation is changing the capabilities of newly emerging destructive (i.e. the contour method) and non-destructive (i.e. magnetic and high-energy synchrotron X-ray strain mapping) residual stress measurement techniques for evaluating ferritic and austenitic pressure vessel components are contrasted against more well-established methods. These new approaches offer the potential for obtaining area maps of residual stress or strain in welded plants, mock-up components or generic test-pieces. The mapped field may be used directly in structural integrity calculations, or indirectly to validate finite element process/structural models on which safety cases for pressurised nuclear systems are founded. These measurement methods are complementary in terms of application to actual plant, cost effectiveness and measurements in thick sections. In each case an exemplar case study is used to illustrate the method and to highlight its particular capabilities.

Economic and safe management of operating nuclear power plant is increasingly dependent upon structural integrity assessments for pressure vessels and piping. The residual stress distribution assumed in defect assessments for welded joints often have a deciding influence on the analysis outcome. Guidance on characterising conservative levels of weld residual stress can be found in structural integrity codes and procedures such as R6, API 579 and BS7910. There is an increasing need to develop more realistic and reliable residual stress distributions that will deliver more accurate integrity assessments. However, future development of such distributions will have to deal convincingly with what is often termed the “innate scatter” of weld residual stresses. This paper first identifies and illustrates some of the origins of apparent innate scatter. The stability of the welding process is examined. The importance of transient weld bead starts/stops and the lay-up of passes in multi-pass welds are demonstrated. Uncertainties associated with two commonly used residual stress measurement techniques are reviewed and simple quantitative studies used to reveal the role of measurement gauge length and, more significantly, errors in spatial location on the level of measured residual stress. The final part of this paper surveys how structural integrity codes and procedures currently characterise welding residual stresses for defect-assessment purposes and discusses the development of more realistic residual stress profiles based on statistical treatment of scatter and uncertainties.

Hepatocytes, the cells responsible for the metabolic and detoxification processes in the liver, are the predominant target of hepatitis B virus (HBV) infections, a major cause of liver cancer. The limited availability of normal human hepatocytes for cell-culture based studies is a significant challenge in HBV-associated liver cancer research. Therefore, there is a need for miniaturized cell-culture systems that can serve as a platform for studying the effect of HBV infections on hepatocyte physiology. Here, we present a microfluidic platform that can be used to study HBV replication in both rat and human hepatocytes. Polydimethylsiloxane (PDMS) microchannels fabricated using soft lithography techniques served as a culture vessel for both primary rat hepatocytes (PRH) and a human hepatoblastoma cell line, HepG2. The micro cell-culture chamber was then used as a model for HBV replication studies. Cells were grown in static culture conditions and either transfected with an HBV-genome cDNA or infected with the viral genome expressed from a recombinant adenovirus. Supernatants collected from the microchannels were assayed for secreted HBV using polymerase chain reaction (PCR). We achieved approximately 40 and 10% transfection efficiencies in HepG2 cells and PRH respectively, and 80-100% adenoviral infection efficiency in PRH comparable to standard tissue culture methods. Moreover, we successfully detected replicated HBV using our novel platform. This platform can be easily extended to studies involving DNA transfection or HBV infection of primary human hepatocytes since only a small number of cells are required for studies in microfluidic chambers.

A sheet thermal Li beam to study the density contour near X-point and divertor strike points has been developed for the spherical tokamak CPD. The CCD camera with a time resolution of 1 ms and spatial resolution of ∼1 mm can record two-dimensional images of LiI resonance line (300 mm × 500 mm). The performance of the sheet beam is absolutely calibrated by a quartz crystal monitor. The Li flux of 10 18 –10 19 m −2 s −1 is achieved near the X-point. The sheet characteristics of beam width and uniformity are also confirmed. This technique is applied during plasma initiation and electron cyclotron heating phase of plasma in a simple torus with a small vertical field. The formation of vertically stretched plasma at the position of the cyclotron resonance is clearly found. The expansion process towards the low field side is observed and an over dense plasma (>1 × 10 18 m −3 ) is obtained. A model calculation of LiI emission with density range of 1–5 × 10 18 m −3 agrees fairly well with the observations. Over dense plasma formation is also discussed.

Defect assessments for pressure vessels and piping are increasingly used to support the economic and safe management of operating plant. Assessments of defects in welds, however, can be highly sensitive to the through-thickness residual stress profiles assumed in the calculations. This is illustrated for typical stainless steel pipe girth welds, where there is a lack of consensus in structural integrity procedures about what residual stress profiles to use. A general prescription for as-welded residual stress distributions in stainless steel pipe butt welds of arbitrary diameter and thickness,, based solely on finite element studies, is critically examined by comparing the estimated profiles with an array of diverse weld residual stress measurements in pipe welds 16mm to 110mm thick. New ‘more realistic’ formulations for axial and hoop residual stresses are proposed that capture the profiles of both measured and predicted through-thickness residual stresses. They are suitable for use in fracture assessments, when supported by sensitivity studies, for structurally significant defects in non-stress relieved austenitic stainless steel girth welds, where the weld material overmatches the parent in terms of tensile properties. The formulations are validated for a range of weld groove geometries and weld processes, a thickness range of 16mm to 110mm, R/t range of 1.8 to 25 and electrical heat inputs in the range 1.0 to 2.4 KJ/mm. The new approximations are simple to evaluate and suited for incorporation into structural integrity procedures.

Mitochondria undergo dynamic changes in morphology in order to adapt to changes in nutrient and oxygen availability, communicate with the nucleus, and modulate intracellular calcium dynamics. Many recent papers have been published assessing mitochondrial morphology endpoints. Although these studies have yielded valuable insights, contemporary assessment of mitochondrial morphology is typically subjective and qualitative, precluding direct comparison of outcomes between different studies and likely missing many subtle effects. In this paper, we describe a novel software technique for measuring the average length, average width, spatial density, and intracellular localization of mitochondria from a fluorescent microscope image. This method was applied to distinguish baseline characteristics of Human Umbilical Vein Endothelial Cells (HUVECs), primary Goto-Kakizaki rat aortic smooth muscle cells (GK SMCs), primary Wistar rat aortic smooth muscle cells (Wistar SMCs), and SH-SY5Ys (human neuroblastoma cell line). Consistent with direct observation, our algorithms found SH-SY5Ys to have the greatest mitochondrial density, while HUVECs were found to have the longest mitochondria. Mitochondrial morphology responses to temperature, nutrient, and oxidative stressors were characterized to test algorithm performance. Large morphology changes recorded by the software agreed with direct observation, and subtle but consistent morphology changes were found that would not otherwise have been detected. Endpoints were consistent between experimental repetitions (R = 0.93 for length, R = 0.93 for width, R = 0.89 for spatial density, and R = 0.74 for localization), and maintained reasonable agreement even when compared to images taken with compromised microscope resolution or in an alternate imaging plane. These results indicate that the automated software described herein allows quantitative and objective characterization of mitochondrial morphology from fluorescent microscope images.

A study of pressurised cylinders having attached pads was made. The possibility of a fatigue crack developing along one side of the pad was noted. For both defect-free components and components having axial crack-like defects, finite element and limited experimental studies of the local and global deformations were made and results were found to be in close agreement. Both welded and integrally machined pads were studied. It was observed that for defect-free components, the method of pad attachment has little effect on the burst pressure. The presence of a pad was found to increase the burst pressure of cracked components by a small but significant margin. A finite element-based parametric study of pipes with part-penetrating defects and a range of pad geometries has demonstrated that pad size has little influence on the limit load for any of the cracked cases considered. However, pipes with penetrating defects were strengthened by the presence of pads, particularly for thin-walled sections.

In contrast to initial fabrication welds, residual stresses associated with finite length weld repairs tend to exhibit some important invariant features, regardless of actual component configurations, materials, and to some degree, welding procedures. Such invariant features are associated with the severe restraint conditions present in typical repair welding situations. In this paper, residual stress results from several weld repair case studies, using both advanced computational modelling procedures and experimental measurement techniques, are presented and reviewed. From these results, it is evident that weld repairs typically increase the magnitude of transverse residual stresses along the repair compared with the initial weld and that the shorter the repair length the greater the increase in the transverse stress. Also, beyond the ends of the repair the transverse stress sharply falls into compression. For selected cases, predicted stresses are compared with detailed residual stress measurements and the adequacy of finite element simulation procedures is assessed. Welding procedure related parameters (pass lumping, heat input and inter-pass temperature) appear to be more important in analysing weld repairs than in initial fabrication welds. Also great care must be taken when employing simplified two-dimensional cross-section finite element models with applied restraint conditions to simulate the residual stress field at a specific point along the length of a repair.

Neutron diffraction measurements have been performed to quantify directly the three-dimensional residual stress field in a stainless steel pipe girth weld containing a part-circumference weld repair. Adjacent to the repair, the measured through-wall axial stress profile was found to be membrane in character and of tensile magnitude equal to about 60% of the base metal 1% proof stress. The measurements show that the repair procedure substantially increased axial and hydrostatic components of residual stress in the neighbouring heat-affected zone.

Part of the special issue: LSC 2013: Advances in Liquid Scintillation Spectrometry Edited by Alex Tarancón Sanz, José Francisco García Martínez; International audience; Developed for radionuclide standardization using liquid scintillation, the Triple to Double Coincidence Ratio (TDCR) method is applied using coincidence counting obtained with a specific three-photomultiplier system. For activity determination, a statistical model of light emission is classically used to establish a relation between the detection efficiency and the experimental TDCR value. At LNE-LNHB, a stochastic approach of the TDCR modeling was developed using the Monte Carlo code Geant4. The interest of this TDCR-Geant4 model is the possibility to simulate the propagation of optical photons from their creation in the scintillation vial to the production of photoelectrons in photomultipliers. As an alternative to the use of radionuclide sources, first TDCR measurements are presented using a miniature x-ray tube closely coupled to the scintillation vial. The objective of this new set-up was to enable low-energy depositions (lower than 20 keV) in liquid scintillator in order to study the influence of both time and geometrical dependence between PMTs already observed with radioactive sources. As for the statistical TDCR model, the non-linearity of light emission is implemented in the TDCR-Geant4 model using the Birks formula which depends on the kB factor and the scintillation yield. Measurements performed with the x-ray tube are extended to the assessment of these parameters and they are tested afterwards in the TDCR-Geant4 model for activity measurements of $^3$H

Residual stresses are invariably associated with welded joints because of local dilation/contraction of material against itself as well as clamp-imposed restraints. Plate thickness provides considerable self-restraint in the case of heavy section welded joints produced by laser and electron beam welding processes and therefore, is expected to affect the relative magnitudes of the three orthogonal direct components of residual stress — longitudinal, normal and transverse to the welding direction. Computation of residual stress in high energy beam welded 9Cr-1Mo(V, Nb) steel plates, of varying thickness in the 5 mm to 80 mm range, has been carried out using finite element based software, SYSWELD, for a systematic study of the effect of the joint thickness on the relative magnitude of the three orthogonal components of stress. The results show that the distributions of residual stress components can be ranked in order of significance in the order: longitudinal, normal and then transverse. The longitudinal and the normal components of stress show similar cross-weld profiles. The magnitude of the normal component peak shows a direct correlation with the joint thickness and eventually exceeds that of the longitudinal component for an 80 mm thick joint. The results are discussed in the context of our previous residual stress measurements made by neutron diffraction on a thin section laser welded 9Cr-1Mo(V, Nb) steel plate.Copyright © 2014 by ASME

This paper describes the results of weld model analysis and deep hole-drilling measurements undertaken to evaluate residual stress distributions in austenitic and ferritic steel thick section electron beam welds. The work was undertaken in support of a Rolls-Royce and TWI development programme in the UK, for a Reduced Pressure Electron Beam (RPEB, 0.1 to 1mbar) welding process using a mobile local vacuum seal for the manufacture of thick section pressure vessel and pipe welds for nuclear power plant applications. Measurements were undertaken on representative mock-ups including a 160mm thick SA508-3 forging circumferential seam weld, in both the as-welded and furnace post weld heat treated condition. A 316L stainless steel plate butt weld and a 304L pipe girth weld of 80mm and 36mm thickness respectively were also analysed. There is now considered to be sufficient understanding of the residual stress fields generated by thick Electron Beam (EB) welds, to propose through thickness ‘upper bound’ R6 Level 2 stress profiles for use in defect tolerance assessments. The intention is to incorporate residual stress profiles of this type into the R6 structural integrity assessment procedure, following peer review. This would represent a significant step forward in demonstrating technology readiness for plant applications. It is also anticipated that an ASME Code Case will be drafted and proposed for the RPEB welding process. EB welding is a relatively low heat input process, compared with a multi-pass arc weld, such that the fusion zone and heat affected zone are narrow. The centre of an EB weld is the last region to solidify and cool-down, so typically there is a high degree of restraint to weld metal contraction, thereby generating a highly tri-axial yield magnitude tensile stress state at the mid-thickness location. The stress components acting in the longitudinal welding direction and through-thickness orientation tend to be large in the centre of EB welds of high aspect ratio (depth / width). By contrast, lower stress levels are produced on the surfaces acting transverse to the weld plane compared to conventional multi-pass metal arc welds. The transverse stress component is most likely to be required for the assessment of any postulated EB welding defects. The residual stress field decays rapidly with distance from the EB joint into the adjacent parent metal. Symmetrical stress distributions are typically generated in a 1-pass EB plate weld and stress fields are characteristically sinusoidal of wavelength between 1 and 4 times the section thickness.

Significant levels of residual stress are developed in the production of thick-section steel welds. Residual stress can be measured by a variety of methods, although few offer the ability to determine the spatial distribution completely through the thickness. This paper summarizes recent developments in the deep-hole method for measuring residual stresses in thick-section welds. Experimental results obtained from a variety of welded steel components are described. The measurement method has also been used to provide validation for finite element simulations of residual stresses in a welded cylinder-to-nozzle stainless steel component. The paper describes the finite element weld analysis and compares the results with measurements obtained from several locations in the complex geometry. Overall, there is good agreement between the predicted and measured distributions of residual stress, but the magnitudes of predicted stress tend to be greater.

Due to the intrinsic performances of cryogenic detectors such as energy resolution, LPRI has decided to use these devices to improve the quality of the radioactive measurements usually obtained with classical semiconductor detectors. A bolometer with a 10 μg tin absorber has been developed at IAS (Institut d’Astrophysique Spatiale) and has been tested in the cryogenic installation of LPRI; an energy resolution (full width half maximum, FWHM) of 39 eV has been obtained on the Kα line of Mn. Besides these good spectrometry results, an absolute activity measurement using bolometers is proposed by adapting an absorber geometry for 4 π counting.

Low temperature detectors are expected to improve radioactivity measurements as they offer two major advantages compared to classical semiconductor detectors: excellent energy resolution (10 eV for 6 keV X-rays) and 100% detection efficiency for low energy X-rays (i.e. 1–10 keV). The main difficulties encountered in the development of such detectors are their high sensitivity to electromagnetic noise and acoustic vibrations. These difficulties are due to the low energy threshold and the very low temperature required to perform those devices (typically 50 mK). An inverted 3 He/ 4 He dilution refrigerator has been characterized for the development of these detectors for radioactivity metrology applications. Temperature, thermal stability and noise analysis are presented. An energy spectrum was obtained with a sapphire bolometer for the first time in our laboratory.

Thermal cryogenic detectors (bolometers, microcalorimeters) have been operated in the pulse mode to quantify ionizing radiation. These detectors exhibit considerable promise for applications in high resolution spectrometry and integral counting. A compact cryogenic system has been developed that can easily be operated for 15 h at 300 mK. This temperature is probably low enough for α-particle spectrometry. We have recently installed a composite-composite bolometer into this cryostat. The detector consists of two cubic crystals (a sapphire target and a diamond scatterer) coupled to a chemically doped Ge temperature sensor. The time constants of the bolometric signal are such that processing and digital filtering of the pulses is required. Careful examination and processing of the recorded pulses permits the elimination of some causes of the loss in energy resolution (pile-up, microphonics, collection defect). Moreover, the very strong dependence of the gain on the temperature has led us to define stability criteria and to select, a posteriori, measurement periods showing sufficient stability.

Weld modelling guidelines have recently been developed as part of a new section of the R6 integrity assessment procedure, which is used in the UK nuclear power industry. The intention is to improve the consistency of weld modelling procedures, the accuracy of predicted residual stress profiles and confidence in their use for defect tolerance assessments. The first issue of these guidelines is applicable to austenitic stainless steel joints produced using arc welding processes. The components of interest are mainly thick section nuclear pressure vessels and pipe welds where distortion is not the key issue. Recommendations made in the guidelines are largely based on residual stress analysis methods, validated by measurements on a range of weld mock-ups, developed over several years in support of British Energy projects. The guidelines themselves are divided into two main parts. The procedure itself defines the weld residual stress analysis steps and identifies the key modelling decisions to be made. A much larger section then follows, providing advisory notes on how to make key modelling decisions, with reference to supporting documents and three appendices. The purpose of this paper is to describe the application of the guidelines to a typical weld residual stress assessment. This is in the form of a worked example which details the step-by-step application of the guidelines and describes the key modelling decisions that were made at each step of the procedure. The worked example is for a three bead groove weld specimen. This specimen is an austenitic stainless steel plate with a groove running along the entire length of the plate. The groove is filled with three stringer weld beads.Copyright © 2010 by ASME

Welding is known to introduce complex three-dimensional residual stresses of substantial magnitude into pressure vessels and pipe-work. For safety-critical components, where welded joints are not stress-relieved, it can be of vital importance to quantify the residual stress field with high certainty in order to perform a reliable structural integrity assessment. Finite element modeling approaches are being increasingly employed by engineers to predict welding residual stresses. However, such predictions are challenging owing to the innate complexity of the welding process (Hurrell et al., Development of Weld Modelling Guidelines in the UK, Proceedings of the ASME Pressure Vessels and Piping Conference, Prague, Czech Republic, July 26–30, 2009, pp. 481–489). The idea of creating weld residual stress benchmarks against which the performance of weld modeling procedures and practitioners can be evaluated is gaining increasing acceptance. A stainless steel beam 50 mm deep by 10 mm wide, autogenously welded along the 10 mm edge, is a candidate residual stress simulation benchmark specimen that has been studied analytically and for which neutron and synchrotron diffraction residual stress measurements are available. The current research was initiated to provide additional experimental residual stress data for the edge-welded beam by applying, in tandem, the slitting and contour residual stress measurement methods. The contour and slitting results were found to be in excellent agreement with each other and correlated closely with published neutron and synchrotron residual stress measurements when differences in gauge volume and shape were accounted for.

Two major limitations met in the field of ionizing radiation metrology, i.e. energy resolution and detection energy threshold, may be improved by one or two orders of magnitude by using composite bolometers cooled below 300 mK and operating in the pulse mode. The major advantages are: possibility of choosing the absorber (from diamond to BGO: Al2O3, Ge, Si, BaF2, LiF, etc), the absence of statistical noise (phonon quanta are in the 10−4 eV range) and ultimate resolution in the 10−1 eV range for small bolometers. The theoretical and experimental limits are analyzed and solutions for extraneous noise limitations in a complete system are described. The most recent results in alpha-particle and gamma-ray spectrometry using a new design, the composite-composite bolometer, are given. In these, a resolution of 10.5 keV was obtained for 6 MeV alpha particles and < 2.5 keV for241Am 18 keV X rays using a 24 sapphire bolometer. The ideal bolometer concept is also discussed. In this, the simultaneous detection of quanta (due to ionization, fluorescence, ballistic phonons) and thermal energies will make it possible to have lower thresholds by amplification in the target. It should thus be possible to determine the characteristics of the particles (their precise arrival time and the positions of the impacts) and provide improvements in the field of integral counting for the absolute measurement of radioactivity.

Application of electronic speckle pattern interferometry (ESPI) is described to measure the spatial variation in monotonic tensile stress-strain properties along “cross-weld” specimens machined from a stainless steel three-pass welded plate. The technique, which could also be done with digital image correlation, was applied to quantify how the material 0.2%, 1%, 2%, 5%, 10%, and 20% proof stress varied with distance from the center-line of the weldment for parent and weld material associated with the first and final passes. The stress-strain curves measured by the ESPI method correlated closely with stress-strain data measured using conventional test specimens. The measured results are consistent with the hypothesis that thermo-mechanical cycles associated with the welding process work harden previously deposited (single-pass) weld metal and the surrounding parent material. The stress-strain response of the heat affected zone adjacent to the first weld pass is consistent with an accumulated (equivalent monotonic) plastic strain of 6.5% and that of the first pass weld bead was consistent with an accumulated plastic strain of approximately 4% greater than the state of the final pass weld metal.

This paper describes the development of finite element modelling guidelines for the calculation of welding residual stresses. These guidelines form a new section in the R6 procedure, used in the UK nuclear power industry for the assessment of integrity structures containing defects. The intention is to improve the consistency of weld modelling procedures, the accuracy of predicted residual stress profiles and confidence in their use for defect tolerance assessments. The first issue of these guidelines is applicable to austenitic stainless steel joints produced using arc welding processes. The components of interest are mainly thick section nuclear pressure vessels and pipe welds where distortion is not the key issue. Recommendations made in the guidelines are largely based on residual stress analysis methods, validated by measurements on a range of weld mock-ups, developed over several years in support of British Energy projects. Advice is included on the use of 2D and 3D models, welding heat sources, material properties requirements, cyclic hardening and annealing assumptions. The modelling and computational requirements depend on the level of accuracy and degree of validation required. This is likely to be a function of the defect tolerance in the structure. In future issues, the R6 modelling guidelines will be supported by weld validation benchmarks. This will provide a detailed manufacturing record and measurement data from controlled weld mock-ups (including specimen design, welding parameters, thermo-mechanical properties, thermocouple data and stress measurements). It is also planned to develop these guidelines to include ferritic steel and dissimilar metal welds. The metallurgical behaviour in ferritic steel welds is more complex, since micro-structural phase transformations occur. Guidance will be provided on modelling post-weld heat treatment (PWHT) applied to pressure vessel welds and stress relaxation by creep. In modelling dissimilar metal welds, it is necessary to provide advice on dealing with the structural discontinuity at material interfaces and overcome FE solution convergence problems.

Continuous renal replacement therapies (CRRT) are often used to manage complex acid-base problems in critically ill patients. These techniques allow a constant manipulation of the plasma composition. Several technical factors from CRRT influence the acid-base status; namely, the effluent rate, the operational characteristics of the technique, the content of the solutions and the metabolic rate of the buffer. This article reviews the common acid base disorders occurring in the intensive care unit, using both the anion gap and the strong ion gap approaches, and describes the influence of CRRT on acid-base physiology. The use of CRRT as a customized therapy for acid-base disorders is discussed, allowing an integration of both physiological and technical concepts. (Int J Artif Organs 2008; 31: 6–14)

It is unlikely that any engineering component is entirely free from residual stress because of the material processing, fabrication and service load history. Residual stresses originate from the elastic accommodation of misfits between different regions in a structure. The interaction between the misfit and the restraint of the surrounding material and structure determines the magnitude of the resultant residual stress and its length scale. In order to assess the influence of residual stress on fracture, it is essential to quantify the residual stress field over the length scales of concern. This paper identifies the residual stress length scales that must be considered in fracture mechanics analyses for welded joints in engineering structures and proposes a new approach for the treatment of short length scale stresses. The findings are illustrated by results from recent weld residual stress finite element simulations and measurement studies.

Thermal and mechanical processes during welding introduce complex three-dimensional distributions of residual stress. Management of residual stresses represents a major challenge for engineers in order to achieve safe and reliable operation of existing engineering plants. Consideration of how such stresses vary through the wall within welded components is critical in structural integrity assessments. Development of more accurate and realistic weld residual stress profiles through statistical analysis of high quality measured data is highly desirable. This can not be achieved without adequate interpretation of measured weld residual stress data through the development of an appropriate framework. This paper proposes a framework for analysing measured data at four levels of complexity depending on its spatial distribution. The framework provides clear guidance on how to perform appropriate statistical analyses of residual stress data and proposes how to deal with some practical issues that may arise from various stress measurements; for example the gauge size, spatial distribution, measurement uncertainties and data analysis assumptions. Parts of the proposed framework are then applied to measured stress data in a simple welded laboratory test specimen.Copyright © 2008 by ASME

Numerical methods have been established to simulate welding processes, often based around the use of methods which represent the welding process in a simplified manner. Simplified methods include simultaneous deposition of weld beads and bead lumping where stringers or individual weld beads are grouped together and deposited. These approaches are widely accepted, however the requirement for simplified methods often results in compromises to the solution accuracy usually driven by limitations in data and the capability of computing hardware. In many cases this compromise in accuracy is acceptable providing it is well understood, however there are frequently cases where such simplifications are unacceptable and improved representation of the welding process is required. In practice this generally implies the requirement for a full moving heat source simulation. The transition from simplified simulation methods to the next technical step, full moving heat source simulations, is now possible for a wide variety of scenarios as will be demonstrated in this paper. This paper presents two specific cases, a 3 pass slot weld and a multipass repair weld, where full moving heat source simulations have been considered necessary. For each of these cases the reasons why moving heat source methods are necessary and the benefits that this more demanding simulation technique offers are described. Furthermore the predicted residual stress results are compared with residual stress measurements using a variety of measurement techniques. The work provides an extremely useful insight into how moving heat source methods are now considered a practical analysis method for a wide variety of real world problems. Of further consideration is the fact that in the 2 years since the work reported in this paper was undertaken computing performance would have at least doubled.Copyright © 2008 by ASME

Knowledge of constitutive material stress strain properties is important for reliable prediction of weld residual stress fields using analytical stress simulation techniques. The present work investigates the surface stress strain behaviour of a 3-pass groove-welded austenitic stainless steel disc. A relatively novel electronic speckled pattern interferometry (ESPI) technique was employed to monitor the surface deformation pattern across the weld, HAZ and parent metal of the specimens with very high spatial resolution. The deformation data was then analysed to determine the constitutive stress-strain property across the welded specimen. The analyses show very different patterns of proof stress variation across the pass I and pass III weld metal. The accumulated plastic strain in the pass I weld metal resulted in an increase of the 0.2% PS value by 175 MPa.

Residual stresses originate from the elastic accommodation of misfits between different regions in a structure. The interaction between the misfit and the restraint of the surrounding structure determines the magnitude of the resultant residual stress and its length-scale. This paper defines the residual stress length-scales that must be considered in engineering fracture mechanics analyses for welded joints by identifying the crack length-scale of concern. This information is used to estimate measurement length-scale requirements to quantify the stress field and the length-scale that must be represented in finite element weld residual stress simulations

A statistical approach based on Bayes’ theorem has been applied to determine the ‘best estimate’ means of two sets of measured residual stress profiles at various point locations through the depth of a stainless steel edge welded beam. Residual stresses introduced into an AISI Type 316H stainless steel beam (250mm × 50mm × 10mm) by welding along the 10mm edge have been measured using high energy synchrotron and neutron diffraction techniques. Mean values of measured residual stresses are compared with predicted stresses obtained from a two-dimensional finite element simulation employing isotropic, kinematic and mixed isotropic-kinematic hardening models. The accuracy of the prediction has been assessed using a root mean square error approach (RMS).Copyright © 2007 by ASME