Conservatoire national des arts et métiers

About: Conservatoire national des arts et métiers is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 3573 authors who have published 7127 publications receiving 141430 citations. The organization is also known as: CNAM & Conservatoire des arts et métiers.

A full-field optical method for the experimental analysis of reinforced concrete beams repaired with composites

Abstract: In this paper, four-point bending tests are conducted on Reinforced Concrete (RC) beams with flexural and shear deficiencies. Beams are repaired with externally bonded composite sheets. A full-field optical method, called the grid method, is utilized for measuring displacement fields over predefined areas of interest. The paper firstly describes the basic principle of the grid method. An effort is done for defining accurately the measurement resolution and the spatial resolution. Then, the grid method is applied onto RC beams repaired with Carbon-Fibre-Reinforced-Plastic (CFRP) sheets in flexure. A measurement of crack widths all along the crack length is achieved. Subsequently, crack bridging by the bonded CFRP sheet is characterized. Another example is given for a repair in shear. The grid method is utilized for measuring strain fields over a Glass-Fibre-Reinforced-Plastic sheet which is bonded onto cracked concrete. Strain concentrations are detected at the location of cracks. Moreover, the evolution of strain fields with increasing loads leads to an interpretation of failure mechanism. Finally, both examples prove the great potentiality of the grid method for a sharp characterization of structures containing cracks. The results obtained for shear and flexural strengthening with composites, are original.

Some recent results on the design and implementation of interval observers for uncertain systems

Abstract: Abstract Based on the theory of positive systems, the goal of interval observers is to compute sets of admissible values of the state vector at each instant of time for systems subject to bounded uncertainties (noises, disturbances and parameters). The size of the estimated sets, which should be minimised, has to be proportional to the model uncertainties. An interval estimation can be seen as a conventional point estimation (the centre of the interval) with an estimation error given by the interval radius. The reliable uncertainties propagation performed in this context can be useful in several fields such as robust control, diagnosis and fault-tolerant control. This paper presents some recent results on interval observers for several dynamical systems classes such as continuous-time and switched systems.

Affine Models for Credit Risk Analysis

Abstract: Continuous-time affine models have been recently introduced in the theoretical financial literature on credit risk. They provide a coherent modeling, rather easy to implement, but have not yet encountered the expected success among practitioners and regulators. This is likely due to a lack of flexibility of these models, which often implied poor fit, especially compared to more ad hoc approaches proposed by the industry. The aim of this article is to explain that this lack of flexibility is mainly due to the continuous-time assumption. We develop a discrete-time affine analysis of credit risk, explain how different types of factors can be introduced to capture separately the term structure of default correlation, default heterogeneity, correlation between default, and loss-given-default; we also explain why the factor dynamics are less constrained in discrete time and are able to reproduce complicated cycle effects. These models are finally used to derive a credit-VaR and various decompositions of the spreads for corporate bonds or first-to-default basket. Copyright 2006, Oxford University Press.

Increased production of eicosapentaenoic acid by Skeletonema costatum cells after decantation at low temperature.

Abstract: Coagulation of Skeletonema costatum biomass was induced at alkaline pH in enriched sea-water to concentrate the microalgal suspensions by decantation Incubation of the concentrated cultures at 15 °C after return at pH 75 preserved cell viability and increased the yield of lipid extraction and the 20:5(n-3) fatty acid content of the diatom biomass