Calibration and improved prediction of computer models by universal Kriging

This paper addresses the use of experimental data for calibrating a computer model and improving its predictions of the underlying physical system. A global statistical approach is proposed in which the bias between the computer model and the physical system is modeled as a realization of a Gaussian process. The application of classical statistical inference to this statistical model yields a rigorous method for calibrating the computer model and for adding to its predictions a statistical correction based on experimental data. This statistical correction can substantially improve the calibrated computer model for predicting the physical system on new experimental conditions. Furthermore, a quantification of the uncertainty of this prediction is provided. Physical expertise on the calibration parameters can also be taken into account in a Bayesian framework. Finally, the method is applied to the thermal-hydraulic code FLICA 4, in a single phase friction model framework. It allows to improve the predictions of the thermal-hydraulic code FLICA 4 significantly

Pinel-Hauterive – Hauterive

Identifiant de l'opération archéologique : 025435 Date de l'opération : 2008 (SU) Dans le cadre de l’agrandissement de l’usine de traitement des eaux du Lot, il a été mis au jour un certain nombre de structures romaines, dont un four ayant produit des pièces liées à la construction romaine. Le site se trouve sur la berge alluvionnaire récente dominant la rive droite du Lot en pied de falaise. Il y a une vingtaine d’années, lors de travaux d’agrandissement précédents, le site avait livré l’ext..

Applying diffuse ultrasound under dynamic loading to improve closed crack characterization in concrete

International audienceRecent studies show the ability of diffuse ultrasound to characterize surface breaking cracks in concrete. However, derived parameters are sensitive to the presence of partially opened zones along the crack whose pattern may differ from one sample to another. The aim of this letter is to study the variation of diffuse ultrasound parameters while the sample is driven by a low frequency bending load which alternatively opens and closes the crack, allowing to access supplementary information about its morphology. The results show the sensitivity of the method for various crack depths and highlight its potential for concrete nondestructive evaluation

An experimental evaluation of two effective medium theories for ultrasonic wave propagation in concrete

9 pagesInternational audienceThis study compares ultrasonic wave propagation modeling and experimental data in concrete. As a consequence of its composition and manufacturing process, this material has a high elastic scattering (sand and aggregates) and air (microcracks and porosities) content. The behavior of the "Waterman-Truell" and "Generalized Self Consistent Method" dynamic homogenization models are analyzed in the context of an application for strong heterogeneous solid materials, in which the scatterers are of various concentrations and types. The experimental validations of results predicted by the models are carried out by making use of the phase velocity and the attenuation of longitudinal waves, as measured by an immersed transmission setup. The test specimen material has a cement-like matrix containing spherical inclusions of air or glass, with radius close to the ultrasonic wavelength. The models are adapted to the case of materials presenting several types of scattering particle, and allow the propagation of longitudinal waves to be described at the scale of materials such as concrete. The validity limits for frequency and for particle volume ratio can be approached through a comparison with experimental data. The potential of these homogenization models for the prediction of phase velocity and attenuation in strongly heterogeneous solids is demonstrated

Influence of the depth and morphology of real cracks on diffuse ultrasound in concrete: a simulation study

International audienceThe aim of the present paper is to simulate the propagation of diffuse ultrasonic energy in concrete in the presence of a real crack. The numerical model is presented and validated by the comparison with experimental data from the literature. Unlike most of the studies which consider a crack as a notch, a realistic crack morphology exhibits partial contacts along its lips. These contacts are modeled in order to study their influence on the diffusion parameters. The feasibility of determining the contact density of the crack is shown, revealing practice implications for non-destructive crack sizing and imaging in concrete

Post mortem human subject and dummy response in frontal deceleration

28ème congrès de la société de biomécanique, POITIERS, FRANCE, 11-/09/2003 - 12/09/2003In the European Union, the assessment of die protection offered by a vehicle to a restrained occupant in case of frontal collision, is based on biomechanical data measured on the Hybrid III crash test dummy as described by the European Frontal Directive (Directive 96/79/EC). Ibis dummy was developed in the 70's and is based on biomechanical knowledge from that time. The Thor dummy (Test device for Human Occupant Restraint) developed by NHTSA (USA Administration) is based on more recent biomechanical knowledge. Many parts of the dummy have been designed and modified to produce a more humanlike response to frontal impact loading. The general objective of the FID European research program (improved Frontal Impact protection through a world frontal impact Dummy) is a European contribution to the evaluation of a worldwide dummy in the frontal impact. The paper presents new biomechanical data, based PMHS (Post Mortem Human Subject) tests, under different frontal impact conditions. The same tests with exactly the same instrumentation mounted at the same location were performed with Hybrid III and with the Thor-alpha to assess die biofidelity of these dummies with respect to these biomechanical data

Sustainability and Production Costs in the Global Farming Sector: Comparative Analysis and Methodologies

This report constitutes a comprehensive compilation and synthesis of the principle issues and outcomes of the joint Institute for prospective Technological Studies / Directorate-General for Agriculture and Rural Development workshop on "Sustainability and Production Costs in the Global Farming Sector: Comparative Analysis and Methodologies" held in Brussels between 21-22 June 2011. Gathering a range of international experts and specialists in the field of production costs analysis and development, covering a range of strategic agricultural sectors of global importance, the workshop aimed to review methodologies and approaches to calculating production costs used in various sectors nationally and globally, with emphasis on exploring the applicability for effective international comparisons. A special attention was given to the methodologies and approaches for data collection and processing, factor market structure and policy inter-linkages, sectoral coverage, horizontal technical issues, and the implications for global agricultural markets. Based on the participant deliberations and discussions, a number of practically based policy recommendations towards achieving such comparisons were highlighted. The production of this report, following completion of the workshop, has been the responsibility of the IPTS. This task has been facilitated through collaboration with four internationally recognised experts (Folkhard Isermeyer, von Thünen-Institute, Germany (Chapter 2), Dan L. Cunningham, University of Georgia, USA (Chapter 3), Jean-François Garnier, ARVALIS, France (Chapter 4), Ashok K. Mishra, Louisiana State University, USA (Chapter 5)) acting as rapporteurs for each of the workshop's four technical sessions, whose efforts in capturing the principle issues and outcomes of their respective session has been instrumental towards realisation of this report. Stephen Langrell, Pavel Ciaian and Sergio Gomez y Paloma acted as Editors and compiled Chapters 1 and 6. This report constitutes a particular and comprehensive technical overview of the state of production costs calculations for the sectors under consideration at global level, and a consideration of the prospects for effective international comparison. It reviews methodologies applied for production costs calculation at national and global level followed by the discussion on methodologies used for animal and arable crop sectors. Finally, the report discusses horizontal issues related to production costs calculations. The report closes with policy-relevant conclusions as a basis for policy recommendations. It is envisaged that this report will provide a valuable source of technical and conceptual information for on-going policy considerations, both at EU and third country/international level.JRC.J.4-Agriculture and Life Sciences in the Econom

Compliance thoracique et abdominale de l'enfant par observation de traitements physiothérapiques

Colloque Sécurité dans le transport, LAMEFIP ENSAM CER, BORDEAUX, FRANCE, 11-/10/2006 - 13/10/2006Chaque jour 2 enfants sont tués sur les routes européennes et 200 sont blessés, ce qui représente un coût socio-économique élevé pour la Communauté Européenne. Les principaux segments corporels blessés sont la tête (30%), le thorax (30%) et l'abdomen (10%). Le fait d’observer une si faible réduction de la mortalité en dépit de l’utilisation de DRE (Dispositif de Retenue enfant – approuvé par la CEE) souligne l'importance d’une recherche continue dans le cadre de la sécurité de l’enfant. Bien que beaucoup d'initiatives aient été prises comme par exemple dans les projets en Europe, CREST(Child REstraint SysTem for cars, de janvier 1996 à décembre 2000) et CHILD (Advanced methods for improved Child safety, de septembre 2002 à septembre 2006), les marges de progression peuvent être considérées comme importantes. Le principal facteur contribuant à cette situation est le manque de connaissances biomécaniques spécifiques de l’enfant et les paramètres physiques associés. De part ce manque de connaissances, la bio-fidélité et la pertinence des réponses mécaniques de mannequins pour l’analyse d’accidents d’enfant, peuvent être améliorées comme dans les secteurs tels que la compliance thoracique et abdominale d'un enfant. La compliance thoracique et abdominale représente la capacité de déformation sous l'effet d’un chargement mécanique. Nous proposons de présenter dans ce papier le protocole et la faisabilité de mesurer cette raideur en observant des manipulations thoraciques et abdominales effectuées dans le cadre de traitements physiothérapiques. Le déplacement de la partie supérieure de la main et la charge appliquée par le praticien sont enregistrés. Une analyse tridimensionnelle est exécutée pour reconstruire les déplacements. L’analyse de plus d’observations en fonction de plusieurs variables comme par exemple l'âge, le sexe et l'anthropométrie sera réalisée ultérieurement. Par conséquent c'est seulement par une augmentation décisive des connaissances scientifiques que des avancées importantes pourront être réalisées vers des normes améliorées et une conception plus efficace des dispositifs de retenue enfant La pertinence de la recherche spécifique liée à l’enfant a été soulignée par le Groupe de Recherche du CNRS en « biomécanique des chocs » (GDR CNRS 2610) et à fait l’objet d’une demande de soutien au près de l’ANR au printemps 2006