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Saint-Étienne, France

Belaud V.,Ecole Centrale Lyon | Valette S.,Ecole Centrale Lyon | Stremsdoerfer G.,Ecole Centrale Lyon | Beaugiraud B.,Ecole Centrale Lyon | And 2 more authors.
Scanning | Year: 2014

We have investigated femtosecond (fs) laser (130-fs, 800-nm, 5-kHz) ablation of polypropylene (PP). The following laser process conditions were varied: power density and number of pulses. The morphological parameters' response (depth, ablation diameter, ablation volume) to the laser process conditions, measured by an optical profiler, was investigated by the statistical analysis technique to determine the relationship between them. For this, the simple linear regression and the multiple linear regressions are compared. The simple linear regression shows that the ablation volume follows a linear relationship with the product of the power and the number of pulse. © 2014 Wiley Periodicals, Inc.

Gouiffes M.,University Paris - Sud | Collewet C.,French Institute for Research in Computer Science and Automation | Fernandez-Maloigne C.,University of Poitiers | Tremeau A.,Laboratoire Hubert Curien
Computer Vision and Image Understanding | Year: 2012

Since modeling reflections in image processing is a difficult task, most computer vision algorithms assume that objects are Lambertian and that no lighting change occurs. Some photometric models can partly answer this issue by assuming that the lighting changes are the same at each point of a small window of interest. Through a study based on specular reflection models, we explicit the assumptions on which these models are implicitly based and the situations in which they could fail. This paper proposes two photometric models, which compensate for specular highlights and lighting variations. They assume that photometric changes vary smoothly on the window of interest. Contrary to classical models, the characteristics of the object surface and the lighting changes can vary in the area being observed. First, we study the validity of these models with respect to the acquisition setup: relative locations between the light source, the sensor and the object as well as the roughness of the surface. Then, these models are used to improve feature points tracking by simultaneously estimating the photometric and geometric changes. The proposed methods are compared to well-known tracking methods robust to affine photometric changes. Experimental results on specular objects demonstrate the robustness of our approaches to specular highlights and lighting changes. © 2012 Elsevier Inc. All rights reserved.

Singh K.,Fraunhofer Institute for Intelligent Analysis and Information Systems | Both A.,Mercateo AG | Diefenbach D.,Laboratoire Hubert Curien | Shekarpour S.,University of Bonn
Proceedings - 2016 IEEE 10th International Conference on Semantic Computing, ICSC 2016 | Year: 2016

Question answering (QA) is one of the biggest challenges for making sense out of data. The Web of Data has attracted the attention of the QA community and recently, a number of schema-aware QA systems have been introduced. While research achievements are individually significant, yet, integrating different approaches is not possible due to lack of a systematic approach for conceptually describing QA systems. In this paper, we present a message-driven vocabulary built upon an abstract level. This vocabulary is concluded from conceptual views of different QA systems. In this way, we are enabling researchers and industry to implement message-driven QA systems and to reuse and extend different approaches without interoperability and extension concerns. © 2016 IEEE.

Povarnitsyn M.E.,Moscow Institute of Physics and Technology | Itina T.E.,Laboratoire Hubert Curien | Levashov P.R.,Moscow Institute of Physics and Technology | Khishchenko K.V.,Moscow Institute of Physics and Technology
Physical Chemistry Chemical Physics | Year: 2013

Laser ablation in liquids is now commonly used to produce colloidal nanoparticles (NPs) that have found numerous applications in different areas. In experiments, NPs of different materials can be rather easily obtained by using laser systems with various pulse durations, shapes, wavelengths, and fluences. In this paper, we focus our attention on metal (gold) NPs produced by ultra-short laser pulses. To better understand the mechanisms of the NPs formation, we perform modeling of femtosecond laser interactions with a gold target in the presence of liquid (water). Simulation of the ablation process over several nanoseconds shows that most of the primary NPs originate from the ablated metastable liquid layer, whereas only a minority is formed by condensation inside the cavitation bubble. These particles will further grow/evaporate, and coagulate during a much longer collision stage in the liquid colloid. This journal is © 2013 the Owner Societies.

Lachheb S.,C2MFF | Colantoni P.,C2MFF | Dinet E.,Laboratoire Hubert Curien
5th European Conference on Colour in Graphics, Imaging, and Vision and 12th International Symposium on Multispectral Colour Science 2010, CGIV 2010/MCS'10 | Year: 2010

A set of colours aesthetically pleasant are described as harmonious in the language of human visual perception. As this notion encloses a subjective part, a psychophysical experiment was carried out to estimate the perception of colour harmony for combinations of paintings with the uniform colour of walls on which they are hung. The experiment, that involved 38 observers, was based on accurate colours built upon a specific colour flow. Participants were asked to judge the colour harmony of combinations of a sample of 7 selected paintings with backgrounds uniformly coloured in 3 different ranges of colours - achromatic colours, tones derived from the global average colour of the considered painting and tones derived from the complementary of the global average colour of the considered painting. Results demonstrate that the best colour harmony is obtained when the average colour of paintings is used to colour their background. The experiment presented in this paper clearly shows that the white colour usually used for walls in museums does not optimize the colour harmony.

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