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排序方式: 共有1411条查询结果,搜索用时 15 毫秒
961.
Nicolas Leconte Bertrand Langrand Eric Markiewicz 《Journal of Computational and Applied Mathematics》2008
The paper deals with the modelling of riveted assemblies for full-scale complete aircraft crashworthiness. Many comparisons between experiments and FE computations of bird impacts onto aluminium riveted panels have shown that macroscopic plastic strains were not sufficiently developed (and localised) in the riveted shell FE in the impact area. Consequently, FE models never succeed in initialising and propagating the rupture in the sheet metal plates and along rivet rows as shown by experiments, without calibrating the input data (especially the damage and failure properties of the riveted shell FE). To model the assembly correctly, it appears necessary to investigate on FE techniques such as Hybrid-Trefftz finite element method (H-T FEM). Indeed, perforated FE plates developed for elastic problems, based on a Hybrid-Trefftz formulation, have been found in the open literature. Our purpose is to find a way to extend this formulation so that the super-element can be used for crashworthiness. To reach this aim, the main features of an elastic Hybrid-Trefftz plate are presented and are then followed by a discussion on the possible extensions. Finally, the interpolation functions of the element are evaluated numerically. 相似文献
962.
Benjamin Coesnon Mourad Heniche Christophe Devals François Bertrand Philippe A. Tanguy 《国际流体数值方法杂志》2008,58(4):427-449
This work deals with the development of a fast three‐dimensional numerical strategy for the simulation of viscous fluid flow in complex mixing systems. The proposed method is based on a distributed Lagrange multiplier fictitious domain method and the use of the low‐cost MINI finite element. Contrary to the previous fictitious domain method developed by our group a few years ago, the underlying partial differential equations are solved here in a coupled manner using a consistent penalty technique. The method is discussed in detail and its precision is assessed by means of experimental data in the case of an agitated vessel. A comparison made with our existing fictitious domain method and its decoupled Uzawa‐based solver clearly shows the advantages of resorting to the MINI finite element and fully coupled solution strategy. The new technique is then applied to the simulation of the flow of a Newtonian viscous fluid in a three‐blade planetary mixer in the context of the production of solid propellants. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
963.
Benedicte Friot David Boyd Kimberley Willis Bertrand Donnio Goran Ungar Duncan W. Bruce 《Liquid crystals》2013,40(5):605-611
The tricatenar, hydrogen-bonded complexes formed between alkoxystilbazoles and an imine were found to be mesomorphic. Subsequently, related tetracatenar complexes were also investigated and found to be non-mesomorphic. We report the transition temperatures of these complexes and discuss structural modifications. 相似文献
964.
Alain Bertrand Togueu Motcheyo Clément Tchawoua Martin Siewe Siewe Joel Durel Tchinang Tchameu 《Physics letters. A》2011,375(7):1104-1109
We show that a discrete electrical transmission line, such as a Band-pass filter is modeled by the Salerno equation at the upper cutoff mode. Special interest is paid to the investigation of stationary localized solutions supported by this equation for some given experimental parameters. Applying a map approach, the profiles of single and two bright solitons are obtained. Linear stability and direct numerical simulations are performed and the results show that a single bright soliton is stable while two bright ones are unstable and lead to a single bright soliton. Finally, we show that the lifespan of two hump solitons increases depending on the length thrust range of the kicked initial condition. 相似文献
965.
A Raman Differential Absorption Lidar for Ozone and Water Vapor Measurement in the Lower Troposphere
Benoicaront Lazzarotto Philippe Quaglia Valentin Simeonov Gilles Larchevěque Hubert van den Bergh Bertrand Calpini 《International journal of environmental analytical chemistry》2013,93(1-4):255-261
Abstract A new way of measuring ozone and water vapor in the Planetary Boundary Layer (PBL) is proposed. The method is based on the simultaneous measurement of the Raman backscattering in the UV by O2, N2 and H2O, using a single pump beam at 266 nm. The ozone concentration is retrieved from the differential absorption of the N2 and O2 Raman backscattered signals, while the water vapor is measured using the classical Raman scheme. We present some preliminary results showing daytime ozone measurements in good correlation with a point monitor. 相似文献
966.
Bertrand Michel 《商业与工业应用随机模型》2011,27(4):434-449
The specific distribution of hydrocarbon field sizes has a deep impact on the dynamics of the production inside a basin. This paper proposes a probabilistic model based on the field size distribution, taking into account the launching production process of the fields. This model can be seen as a ‘bottom‐up’ probabilistic method to simulate and predict oil production. The asymptotic results obtained allow us to propose relevant fitting to real production curves. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
967.
Jean‐Philippe Echard Loïc Bertrand Dr. Alex von Bohlen Dr. Anne‐Solenn Le Hô Dr. Céline Paris Dr. Ludovic Bellot‐Gurlet Dr. Balthazar Soulier Agnès Lattuati‐Derieux Dr. Sylvie Thao Laurianne Robinet Dr. Bertrand Lavédrine Prof. Stéphane Vaiedelich 《Angewandte Chemie (International ed. in English)》2010,49(1):197-201
968.
Brooks D. Rabideau Pascal Moucheront François Bertrand Stéphane Rodts Nicolas Roussel Christophe Lanos Philippe Coussot 《ournal of non Newtonian Fluid Mechanics》2010,165(7-8):394-408
Extrusion tests were performed by forcing a well-characterized model yield stress fluid from a cylindrical cartridge through various cylindrical extrusion dies using a variety of different piston velocities. In this study the Bingham number within the die ranged from 0.1 to 10. MRI techniques allowed for the non-invasive determination of the local velocity within the extruded material in the range [0.015; 20 mm s?1]. The velocity profile within a very long die was determined by MRI and agreed very well with the analytical results for the flow of a Herschel–Bulkley fluid within a conduit using parameters determined from independent rheometrical tests, validating both the rheological approach and the accuracy of the MRI techniques. Although the velocity was determined by MRI in the upper and lower zones separately, the intersection of these zones showed great agreement, providing an entire view of the extrusion process. In the range of Bingham number studied, the velocity field for a given contraction ratio appeared similar when scaled by the piston velocity, with a dimpled acceleration zone above the die and lateral dead zones varying negligibly with the piston velocity. For a further analysis the experimental results were compared with the results of numerical simulations. Finite element simulations using an elastic solids model were performed to provide this comparison. It was found that this model did well in representing the characteristics of extrusion flow seen in the experiments; an aspect that was not present in the biviscous simulations. The MRI results show that for the range of values studied, both the piston velocity and the contraction ratio have little effect on the characteristics of the flow, including the size and location of the apparent dead zones. It was found that with an appropriate scaling the central, longitudinal velocity follows a master curve. A decreasing contraction ratio, on the other hand, appears to increase the size of the weak velocity region, in contrast with the simulation results. 相似文献
969.
Chamseddine Derabli Raouf Boulcina Gilbert Kirsch Bertrand Carboni Abdelmadjid Debache 《Tetrahedron letters》2014
An efficient and simple method for the synthesis of 1,2-dihydroquinazolines catalyzed by 4-(N,N-dimethylamino)pyridine (DMAP) from readily available aromatic or heteroaromatic aldehydes, 2-aminobenzophenone, and ammonium acetate under mild conditions is described. The scope and limitations of the method are discussed. 相似文献
970.
Vignolle J Donnadieu B Bourissou D Soleilhavoup M Bertrand G 《Journal of the American Chemical Society》2006,128(46):14810-14811
In contrast with most of their congeners, acyclic and cyclic C-amino phosphorus ylides behave as genuine carbene and phosphine transfer agents for transition metal centers. They allow the facile synthesis of a variety of metal complexes that feature heteroditopic ligands, such as 1,6-(phosphine)(aminocarbene) systems with a biphenyl backbone. 相似文献