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91.
A texture discretization technique adapted to polycrystalline aggregates with non-uniform grain size
This paper presents a new procedure for the sampling of crystallographic textures into discrete lattice orientations. The method is, for example, useful in order to assign initial grain orientations in crystal-plasticity-based finite element simulation of forming processes. The discretization technique ensures that the orientation sampling is statistically representative of a known orientation distribution function (ODF). Contrary to previous discretization techniques, the new method is valid also when the model microstructure consists of grains with non-uniform size. The accuracy of the texture representation is assessed in the case of cold rolled IF steel. Crystal plasticity theory coupled to finite element modeling is used to predict mechanical planar anisotropy of the sheet. Comparison is made between model predictions assuming, respectively, a uniform or a heterogeneous grain-size distribution. 相似文献
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93.
Roman Jaworski Christel Pierlot Lech Pawlowski Muriel Bigan Maxime Quivrin 《Journal of Thermal Spray Technology》2008,17(5-6):679-684
The synthetic hydroxyapatite (HA, Ca10(PO4)6(OH)2) is a very useful biomaterial for numerous applications in medicine, such as e.g., fine powder for suspension plasma spraying. The powder was synthesized using aqueous solution of ammonium phosphate (H2(PO4)NH4) and calcium nitrate (Ca(NO3) · 4H2O) in the carefully controlled experiments. The synthesized fine powder was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The powder was formulated into water and alcohol based suspension and used to carry out the initial tests of plasma spraying onto titanium substrate. The phase analysis of sprayed coating was made with the XRD. 相似文献
94.
Nanjiang Chen Richard Ducloux Christel Pecquet Julien Malrieux Maxime Thonnerieux Min Wan Jean-Loup Chenot 《International Journal of Material Forming》2011,4(1):45-54
As one of important mechanical joining methods, rivet joints are widely used in buildings, bridges, aircrafts and automotives and in many other fields. Many variables have influences on the response of the rivet joints, such as the geometry of the joints, the material parameters of the parts, the clearance of the assembly, etc. In this paper, a finite element numerical model is developed for the analysis and optimization of the riveting process. Our approach is three-dimensional in order to be able to model non axisymmetric situations of riveting and testing of the joint strength. Four different sizes of solid rivets are considered for simulation and experimental study of the process. The comparison of the results between the numerical simulations and the experiments allows us to validate our approach. 相似文献
95.
Maxime Lenormand Bruno Gon?alves Antònia Tugores José J. Ramasco 《Journal of the Royal Society Interface》2015,12(109)
Cities are characterized by concentrating population, economic activity and services. However, not all cities are equal and a natural hierarchy at local, regional or global scales spontaneously emerges. In this work, we introduce a method to quantify city influence using geolocated tweets to characterize human mobility. Rome and Paris appear consistently as the cities attracting most diverse visitors. The ratio between locals and non-local visitors turns out to be fundamental for a city to truly be global. Focusing only on urban residents'' mobility flows, a city-to-city network can be constructed. This network allows us to analyse centrality measures at different scales. New York and London play a central role on the global scale, while urban rankings suffer substantial changes if the focus is set at a regional level. 相似文献
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Cécile Dobrzynski Maxime Melchior Laurent Delannay Jean‐François Remacle 《International journal for numerical methods in engineering》2011,86(12):1396-1412
In this paper, an original technique is developed in order to build adaptive meshes on periodic domains. The new approach has the important property that it is code‐reused. The procedure is used against three different algorithms, namely, MAdLib ( Int. J. Numer. Meth. Engng 2000; in press), mmg (Proc. 17th Int. Meshing Roundtable, 2008) and the couple Yams (Rapport Technique RT‐0252, 2001) /Ghs3d (Proc. 8th Int. Meshing Roundtable, 1999). None of the latter algorithms needs to be adapted before it is applied to periodic domains. Some examples of adaptation are presented based on analytical, isotropic and anisotropic mesh‐size fields. Periodicity in translation and rotation both are considered. Finally, the mesh adaptation strategy is used in order to reduce the computational cost of a prediction of strain heterogeneity throughout a periodic polycrystalline aggregate deforming by dislocation slip. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
99.
Nanoparticles are now utilized in many diverse biological and medical applications. Despite this, it remains challenging to tailor their surface for specific molecular targeting while maintaining high biocompatibility. To address this problem, we evaluate a phytochelatin-related peptide surface coating to produce functional and biocompatible nanoparticles (NPs) based on fluorescent InP/ZnS and CdSe/ZnS or superparamagnetic FePt and Fe(3)O(4). Using a combination of transmission electron microscopy, size-exclusion chromatography and gel electrophoresis (GE), we demonstrate the excellent colloidal properties of the peptide-coated NPs (pNPs) and the compact nature of the coating (~4?nm thickness). We develop a simple protocol for the monofunctionalization of the pNPs with targeting biomolecules, by combining covalent conjugation with GE purification. We then employ functionalized InP/ZnS pNPs in a live-cell, single-molecule imaging application to specifically target and detect individual proteins in the cell membrane. These findings showcase the versatility of the peptides for preparing compact NPs of various compositions and sizes, which are easily functionalized, and suitable for a broad range of biomedical applications. 相似文献
100.
Lewis F Cloutier M Chevallier P Turgeon S Pireaux JJ Tatoulian M Mantovani D 《ACS applied materials & interfaces》2011,3(7):2323-2331
Coatings are known to be one of the more suited strategies to tailor the interface between medical devices and the surrounding cells and tissues once implanted. The development of coatings and the optimization of their adhesion and stability are of major importance. In this work, the influence of plasma etching of the substrate on a plasma fluorocarbon ultrathin coating has been investigated with the aim of improving the stability and the corrosion properties of coated medical devices. The 316 L stainless steel interface was subjected to two different etching sequences prior to the plasma deposition. These plasma etchings, with H(2) and C(2)F(6) as gas precursors, modified the chemical composition and the thickness of the oxide layer and influenced the subsequent polymerization. The coating properties were evaluated using flat substrates submitted to deformation, aging into aqueous medium and corrosion tests. X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectrometry (ToF-SIMS), ellipsometry, and atomic force microscopy (AFM) were performed to determine the effects of the deformation and the aging on the chemistry and morphology of the coated samples. Analyses showed that plasma etchings were essential to promote reproducible polymerization and film growth. However, the oxide layer thinning due to the etching lowered the corrosion resistance of the substrate and affected the stability of the interface. Still, the deformed samples did not exhibited adhesion and cohesion failure before and after the aging. 相似文献