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101.
102.
Emilie Bosc Fabien Racapé Vincent Jantet Paul Riou Muriel Pressigout Luce Morin Vincent Jantet 《电信纪事》2013,68(11-12):615-625
Multi-view video plus depth (MVD) data offer a reliable representation of three-dimensional (3D) scenes for 3D video applications. This is a huge amount of data whose compression is an important challenge for researchers at the current time. Consisting of texture and depth video sequences, the question of the relationship between these two types of data regarding bit-rate allocation often raises. This paper questions the required ratio between texture and depth when encoding MVD data. In particular, the paper investigates the elements impacting on the best bit-rate ratio between depth and color: total bit-rate budget, input data features, encoding strategy, and assessed view. 相似文献
103.
A method to design finite elements that imbricate with each other while being assembled, denoted as imbricate finite element method, is proposed to improve the smoothness and the accuracy of the approximation based upon low order elements. Although these imbricate elements rely on triangular meshes, the approximation stems from the shape functions of bilinear quadrilateral elements. These elements satisfy the standard requirements of the finite element method: continuity, delta function property, and partition of unity. The convergence of the proposed approximation is investigated by means of two numerical benchmark problems comparing three different schemes for the numerical integration including a cell-based smoothed FEM based on a quadratic shape of the elements edges. The method is compared to related existing methods. 相似文献
104.
105.
Bouchra Wahdame Denis Candusso Xavier François Fabien Harel Jean-Marie Kauffmann Gérard Coquery 《International Journal of Hydrogen Energy》2009
Designs of Experiments (DoE) can be of immediate relevance for various research works conducted in the Fuel Cell (FC) area. DoE techniques allow efficient test definitions for rapid conceptions and well-organised characterisations of FC materials and components, individual cells, stacks or even complete generators. In the DoE method, some statistic-based models can be proposed in pre-stages of physical models. The statistical/numerical relations are used to predict the behaviour of the investigated systems as a function of various operating parameters. Some control strategies can also be developed to optimise relevant criteria like FC voltage, fuel consumption, and maximal electrical power or stack lifetime. 相似文献
106.
107.
Fabien Dhainaut Stan Pietrzyk Pascal Granger 《Applied catalysis. B, Environmental》2007,70(1-4):100-110
This paper reports a kinetic investigation of the global reduction of NO by H2 which has been considered as a probe reaction for characterising the adsorption properties of supported palladium based catalysts. A particular attention has been paid towards the influence of the support on the catalytic properties of Pd, particularly towards the production of undesirable by-products such as nitrous oxide (N2O) and ammonia (NH3). It has been found that the kinetics of the overall NO + H2 reaction on Pd/Al2O3 can be correctly depicted according to a Langmuir–Hinshelwood mechanism involving the dissociation of nitrosyl species assisted by chemisorbed hydrogen atoms. On the other hand, Pd/LaCoO3 exhibits a different kinetic behaviour towards the adsorption of hydrogen depending on the pre-activation thermal treatment. In that case, different mechanisms may occur. 相似文献
108.
In premixed turbulent combustion, reaction rates can be estimated from the flame surface density. This parameter, which measures the mean flame surface area available per unit volume, may be obtained from algebraic expressions or by solving a transport equation. In this study, detailed measurements were performed on a Bunsen-type burner fed with methane/air mixtures in order to determine the local flame surface density experimentally. This burner, located in a high-pressure combustion chamber, allows investigation of turbulent premixed flames under various flow, mixture, and pressure conditions. In the present work, equivalence ratio was varied from 0.6 to 0.8 and pressure from 0.1 to 0.9 MPa. Flame front visualizations by Mie scattering laser tomography are used to obtain experimental data on the instantaneous flame front dynamics. The exact equation given by Pope is used to obtain flame surface density maps for different flame conditions. Some assumptions are made in order to access three-dimensional information from our two-dimensional experiments. Two different methodologies are proposed and tested in term of global mass balance (what enters compared to what is burned). The detailed experimental flame surface data provided for the first time in this work should progressively allow improvement of turbulent premixed flame modeling approaches. 相似文献
109.
E Guerry OC Martin H Tricoire R Siebert L Valentin 《Canadian Metallurgical Quarterly》1996,17(9):1420-1424
We have developed a program to evaluate the influence of DNA stiffness on molecular mobility and conformation during electrophoresis. This (currently) two-dimensional numerical study models DNA as a chain of uniformly charged beads connected to one another by elastic segments, of finite mean size, in the presence of fixed obstacles representing gel fibers. Contrary to the standard biased reptation model (BRM), our Langevin-type dynamics for the chain are microscopic and warrant studies of fine effects such as inner chain orientation. Using this model, we show that the introduction of a persistence length decreases the (saturated) mobility at high electric fields, providing strong evidence that the gel generates a friction force and not only a (dissipation-free) constraint force. We also show that the persistence length leads to an increase of the chain orientation in the field direction. This suggests that DNA stiffness causes the saturation plateau value to be reached for smaller chain sizes than those predicted by the BRM model. 相似文献
110.
We have inferred the wavelength and temperature dependence of the absorption and scattering cross sections of mature soot in an ethylene flame from laser-induced incandescence (LII) and transmittance measurements at 532 and 1064 nm. The LII measurements indicate that the emissivity of soot in a flame deviates from the expected 1/λ dependence. Combining the LII results with transmittance measurements yields single-scattering albedos of 0.058-0.077 at 1064 nm and 0.22-0.29 at 532 nm and values of F(m)/E(m) of 2.2-2.9 at 532 nm and 2.4-3.3 at 1064 nm. These values confirm that scattering must be taken into account when interpreting extinction data at these wavelengths. Our results also indicate increases in the absorption cross section and decreases in the scattering cross section with increasing fluence at low fluences. The increase in absorption cross section is consistent with increases in primary particle size with increasing particle temperature during laser heating. The decrease in scattering cross section could be attributable to an increase in the radius of gyration or a decrease in the fractal dimension of the aggregate with increasing temperature. Alternatively these trends might be the result of changes to the optical properties of the particles with increasing temperature. 相似文献