Search results for " surfaces"
showing 10 items of 176 documents
Magnesium alloys laser (Nd:YAG) cladding and alloying with side injection of aluminium powder
2003
International audience; The development of the high purity magnesium alloys (such as WE43) incites the designers to reconsider them, and the car industry appears, these days, the most interested to use this kind of alloy. However, due to their ignitability and tendency to oxidation, magnesium alloys require surface treatments. A series of experiments was carried out in order to improve the corrosion resistance of two types of magnesium alloys, WE43 and ZE41. In most cases, the substrate surface was treated before laser interaction. Side injection of aluminium powder under a 3 kW cw Nd:YAG laser was employed. The deposited layers present very good bond properties. The resulting microstructur…
Area-minimizing cones in the Heisenberg group H
2021
We present a characterization of minimal cones of class \(C^2\) and \(C^1\) in the first Heisenberg group \(\mathbf{H}\), with an additional set of examples of minimal cones that are not of class \(C^1\).
Synthesis, Characterization and Catalytic Activity of mesoporous Mn-MCM-41 materials
2011
MCM-41 has been synthesized at two different pH using cetyl-trimethylammonium bromide (CTAB) surfactant as template and adding the silica precursor to aqueous solutions containing CTAB. The obtained solids were calcined at 600 ◦C for 4 h. Mn-MCM-41 powders with different Mn/Si molar ratios were prepared using the incipient wetness method, followed by calcination at 550 ◦C for 5 h. At the end of the impregnation process the powders colour changed from white to brown whose intensity depends on manganese quantity. The materials characterization was performed by X-ray diffraction, N2 adsorption, 29Si Cross Polarization–Magic Angle Spinning NMR, and X-ray Photoelectron Spectroscopy. The effects …
Preparation and characterisation of Ce:YAG -polycarbonate composites for white LED
2016
Ce:YAG-polycarbonate composites were prepared with several amounts of Ce:YAG in the range 0.1-5 wt.% by using melt compounding. The structure and morphology of the composites were investigated by means of X-ray diffractometry and transmission electron microscopy. The optical properties of the composites were studied by using photoluminescence spectroscopy. The intermolecular interaction between the polymer and the filler surface was investigated using 13C cross-polarization magic-angle spinning NMR spectroscopy (13C {1H} CP-MAS NMR). The results showed that the dispersion of the particles in the polymer, and the optical properties, depend on the Ce:YAG amount. The composites were combined w…
Optimization and sensitivity analysis of existing deep learning models for pavement surface monitoring using low-quality images
2022
Automated pavement distress detection systems have become increasingly sought after by road agencies to in crease the efficiency of field surveys and reduce the likelihood of insufficient road condition data. However, many modern approaches are developed without practical testing using real-world scenarios. This paper ad dresses this by practically analyzing Deep Learning models to detect pavement distresses using French Secondary road surface images, given the issues of limited available road condition data in those networks. The study specifically explores several experimental and sensitivity-testing strategies using augmentation and hyper- parameter case studies to bolster practical mode…
Blending pieces of Dupin cyclides for 3D modeling and reconstruction : study in the space of spheres
2013
The thesis deals with the blending of canal surfaces in geometric modeling using pieces of Dupin Cyclides. We try to solve a problem of reconstructing real parts manufactured and controlled by the CEA of Valduc. Using the space of spheres in which we can manipulate both points, spheres and canal surfaces, we simplify some problems. This space is represented by a 4-dimensional quadric in a 5-dimensional space, equipped with the Lorentz form, it is the Lorentz space. In the space of spheres, problems of blending canal surfaces by pieces of Dupin cyclides are simplified in linear problems. We give algorithms to make such blends using the space of spheres and after we come back to 3 dimensions …
Numerical analysis of masonry structures via interface models
2001
The present paper is devoted to the theoretical formulation and numerical implementation of an interface model suitable to simulate the behavior of mortar joints in masonry structures. The interface laws are formulated in the framework of elasto-plasticity for non-standard materials in order to simulate the softening response which occurs along the decohesion process in presence of shear and tension tractions. A variable material dilatancy parameter is introduced together with a further geometrical dilatancy related to the roughness of contact surfaces after joint fracture. An asperity model is adopted with the aim to describe the evolution of the contact surface shape during the loss of co…
An exact and efficient approach for computing a cell in an arrangement of quadrics
2006
AbstractWe present an approach for the exact and efficient computation of a cell in an arrangement of quadric surfaces. All calculations are based on exact rational algebraic methods and provide the correct mathematical results in all, even degenerate, cases. By projection, the spatial problem is reduced to the one of computing planar arrangements of algebraic curves. We succeed in locating all event points in these arrangements, including tangential intersections and singular points. By introducing an additional curve, which we call the Jacobi curve, we are able to find non-singular tangential intersections. We show that the coordinates of the singular points in our special projected plana…
Symplectic automorphisms of prime order on K3 surfaces
2006
The aim of this paper is to study algebraic K3 surfaces (defined over the complex number field) with a symplectic automorphism of prime order. In particular we consider the action of the automorphism on the second cohomology with integer coefficients. We determine the invariant sublattice and its perpendicular complement, and show that the latter coincides with the Coxeter-Todd lattice in the case of automorphism of order three. We also compute many explicit examples, with particular attention to elliptic fibrations.
Inkjet printing methodologies for drug screening
2010
We show for the first time a contactless, low-cost, and rapid drug screening methodology by employing inkjet printing for molecular dispensing in a microarray format. Picoliter drops containing a model substrate (D-glucose)/ inhibitor (D-glucal) couple were accurately dispensed on a single layer consisting of the enzymatic target (glucose oxidase) covalently linked to a functionalized silicon oxide support. A simple colorimetric detection method allowed one to prove the screening capability of the microarray with the possibility to assay with high reproducibility at the single spot level. Measurements of the optical signal as a function of concentration and of time verified the occurrence a…