Towards simulations of fuel rod behaviour during severe accidents by coupling TRANSURANUS with SCIANTIX and MFPR-F

Among the applications of the multiscale modelling approach in nuclear fuel rod performance, the coupling of integral thermo-mechanical fuel performance codes with lower-length meso-scale modules is of great interest. This strategy allows to overcome correlation-based approaches with mechanistic ones and test their application in accidental conditions. In this work, we explore the coupling between the TRANSURANUS fuel performance code and two meso-scale modules for fission gas/product behaviour: MFPR-F and SCIANTIX. These modules, coupled within TRANSURANUS, are assessed against the IFA-650.10 loss-of-coolant accident test to analyse their overall impact and highlight future developments toward mechanistic modelling of fission gas during accident scenarios

Absorption spectrum in the wings of the potassium second resonance doublet broadened by helium

We have measured the reduced absorption coefficients occurring in the wings of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened by helium gas at pressures of several hundred Torr. At the experimental temperature of 900 K, we have detected a shoulder-like broadening feature on the blue wing of the doublet which is relatively flat between 401.8 nm and 402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the K-He quasimolecule. The accurate measurements of the line profiles in the present work will sharply constrain future calculations of potential energy surfaces and transition dipole moments correlating to the asymptotes He-K(5p), He-K(5s), and He-K(3d).Comment: 2 figure

Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems

UHV dynamic force and energy dissipation spectroscopy in non-contact atomic force microscopy were used to probe specific interactions with composite systems formed by encapsulating inorganic compounds inside single-walled carbon nanotubes. It is found that forces due to nano-scale van der Waals interaction can be made to decrease by combining an Ag core and a carbon nanotube shell in the Ag@SWNT system. This specific behaviour was attributed to a significantly different effective dielectric function compared to the individual constituents, evaluated using a simple core-shell optical model. Energy dissipation measurements showed that by filling dissipation increases, explained here by softening of C-C bonds resulting in a more deformable nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based on force and dissipation measurements. These findings have two different implications for potential applications: tuning the effective optical properties and tuning the interaction force for molecular absorption by appropriately choosing the filling with respect to the nanotube.Comment: 22 pages, 6 figure

Ultrasonic evaluation of friction stir welds and dissimilar intermixing using synthetic aperture focusing technique

Friction stir welding (FSW) is a recently developed solid-state joining process that uses a specially shaped rotating tool to produce lap or butt joints. At the National Research Council, an inter-institute collaboration was started in 2007 with the goal of exploiting the NDE expertise and applying it for the characterization of friction stir welds for various industrial applications. In particular, very good performance was obtained using ultrasonic immersion or laser-ultrasonics combined with the synthetic aperture focusing technique (SAFT) for detecting lack of penetration in butt joints, discontinuities such as wormholes and hooking in lap joints. Dissimilar metal welds of aluminum and magnesium by FSW are also considered for automotive and aerospace applications. Complex vortex flows are produced during the FSW process that may create intercalated lamellar structures with the possible formation of intermetallic compounds, causing variable hardness and degradation in mechanical properties. A modified version of SAFT that takes into account the difference of ultrasonic velocity in the joint between that of Al and Mg has been developed to study the dissimilar intermixing. Welded samples in the butt configuration with different welding speeds and seam offsets are tested using the immersion technique with the modified SAFT. Results will be presented for both defect detection and weld characterization, and the capabilities and limitations will be discussed.La soudure par friction-malaxage (SFM) est un proc\ue9d\ue9 d\u2019assemblage \ue0 l\u2019\ue9tat solide r\ue9cemment d\ue9velopp\ue9 qui fonctionne au moyen d\u2019un outil rotatif de forme sp\ue9ciale et qui sert \ue0 faire des joints de recouvrement ou des joints bout \ue0 bout. Au Conseil national de recherches du Canada, on a commenc\ue9 une collaboration inter-institut en 2007, avec pour objectif l\u2019exploitation de l\u2019expertise en \ue9valuation non destructive et son application pour la caract\ue9risation de soudures par friction-malaxage pour diverses applications industrielles. En particulier, on a obtenu une tr\ue8s bonne performance par immersion dans des ultrasons ou par une technique ultrasonique \ue0 laser combin\ue9e \ue0 la technique de focalisation \ue0 ouverture synth\ue9tique (TFOS) pour la d\ue9tection du manque de p\ue9n\ue9tration dans des joints bout \ue0 bout, de discontinuit\ue9s comme des tunnels ou des crochets dans des joints de recouvrement. Des soudures m\ue9talliques asym\ue9triques d\u2019aluminium et magn\ue9sium par SFM ont aussi \ue9t\ue9 \ue9tudi\ue9es pour des applications automobiles ou a\ue9rospatiales. Au cours du proc\ue9d\ue9 de SFM, des \ue9coulements complexes avec vortex sont produits. Ceci peut conduire \ue0 la cr\ue9ation de structures lamellaires intercal\ue9es avec formation possible de compos\ue9s interm\ue9talliques, provoquant une duret\ue9 variable et une d\ue9gradation des propri\ue9t\ue9s m\ue9caniques. Une version modifi\ue9e de la TFOS qui tient compte de la diff\ue9rence des vitesses ultrasoniques dans Al et Mg dans le joint a \ue9t\ue9 d\ue9velopp\ue9e afin d\u2019\ue9tudier le m\ue9lange asym\ue9trique. On a test\ue9 des \ue9chantillons soud\ue9s bout \ue0 bout avec diff\ue9rentes vitesses de soudage et diff\ue9rents d\ue9ports de soudage au moyen de la technique par immersion avec TFOS modifi\ue9e. Les r\ue9sultats sont pr\ue9sent\ue9s sur le plan de la d\ue9tection de d\ue9faut et de caract\ue9risation de la soudure. On discute des capacit\ue9s et des limites de cette technique.Peer reviewed: YesNRC publication: Ye

A generalization of Snoek's law to ferromagnetic films and composites

The present paper establishes characteristics of the relative magnetic permeability spectrum $\mu$(f) of magnetic materials at microwave frequencies. The integral of the imaginary part of $\mu$(f) multiplied with the frequency f gives remarkable properties. A generalisation of Snoek's law consists in this quantity being bounded by the square of the saturation magnetization multiplied with a constant. While previous results have been obtained in the case of non-conductive materials, this work is a generalization to ferromagnetic materials and ferromagnetic-based composites with significant skin effect. The influence of truncating the summation to finite upper frequencies is investigated, and estimates associated to the finite summation are provided. It is established that, in practice, the integral does not depend on the damping model under consideration. Numerical experiments are performed in the exactly solvable case of ferromagnetic thin films with uniform magnetization, and these numerical experiments are found to confirm our theoretical results. Microwave permeability measurements on soft amorphous films are reported. The relation between the integral and the saturation magnetization is verified experimentally, and some practical applications of the theoretical results are introduced. The integral can be used to determine the average magnetization orientation in materials with complex configurations of the magnetization, and furthermore to demonstrate the accuracy of microwave measurement systems. For certain applications, such as electromagnetic compatibility or radar absorbing materials, the relations established herein provide useful indications for the design of efficient materials, and simple figures of merit to compare the properties measured on various materials

Suivi archéologique des restaurations du théâtre d'Orange. Présentation du monument et de l'opération

National audienc

Embedding finite and infinite words into overlapping tiles

International audienceIn this paper, we study languages of finite and infinite birooted words. We show how the embedding of free ω-semigroups of finite and infinite words into the monoid of birooted words can be generalized to the embedding of two-sorted ω-semigroups into (some notion of) one- sorted ordered ω-monoids. This leads to an algebraic characterization of regular languages of finite and infinite birooted words that generalizes and unifies the known algebraic characterizations of regular languages of finite and infinite words

A decade of inequality in maternity care: antenatal care, professional attendance at delivery, and caesarean section in Bangladesh (1991–2004)

<p>Abstract</p> <p>Background</p> <p>Bangladesh is committed to the fifth Millennium Development Goal (MDG-5) target of reducing its maternal mortality ratio by three-quarters between 1990 and 2015. Since the early 1990s, Bangladesh has followed a strategy of improving access to facilities equipped and staffed to provide emergency obstetric care (EmOC).</p> <p>Methods</p> <p>We used data from four Demographic and Health Surveys conducted between 1993 and 2004 to examine trends in the proportions of live births preceded by antenatal consultation, attended by a health professional, and delivered by caesarean section, according to key socio-demographic characteristics.</p> <p>Results</p> <p>Utilization of antenatal care increased substantially, from 24% in 1991 to 60% in 2004. Despite a relatively greater increase in rural than urban areas, utilization remained much lower among the poorest rural women without formal education (18%) compared with the richest urban women with secondary or higher education (99%). Professional attendance at delivery increased by 50% (from 9% to 14%, more rapidly in rural than urban areas), and caesarean sections trebled (from 2% to 6%), but these indicators remained low even by developing country standards. Within these trends there were huge inequalities; 86% of live births among the richest urban women with secondary or higher education were attended by a health professional, and 35% were delivered by caesarean section, compared with 2% and 0.1% respectively of live births among the poorest rural women without formal education. The trend in professional attendance was entirely confounded by socioeconomic and demographic changes, but education of the woman and her husband remained important determinants of utilization of obstetric services.</p> <p>Conclusion</p> <p>Despite commendable progress in improving uptake of antenatal care, and in equipping health facilities to provide emergency obstetric care, the very low utilization of these facilities, especially by poor women, is a major impediment to meeting MDG-5 in Bangladesh.</p