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61.
(Meth)acrylic cross‐linked polymer microparticles (CPM, also named microgels) were used as toughening agent for an epoxy/amine network. CPM were mainly based on butyl acrylate and consequently they were rubbery at ambient temperature. Various types of reactive groups were introduced onto the CPM: epoxy, carboxy (meth)acrylic double bonds, and epoxy + acrylic double bonds, carboxyl + methacrylic double bonds. Non functional microparticles were also used. Before any reaction, most of the CPM were soluble in the thermoset precursors. Nevertheless, the CPM functionality strongly influenced their initial miscibility in the epoxy‐amine monomers and their final dispersion in the cross‐linked matrix, as well as the mechanical properties of the network. Non‐functional CPM did not lead to a high increase of fracture toughness because of the low adhesion between microparticles and epoxy matrix. However, fracture toughness was increased with reactive CPM because of better adhesion between the microparticles and the matrix. The best toughness was obtained with microparticles containing two types of reactive groups, allowing at the same time cross‐linking reactions between CPM and chemical bonding between CPM and the epoxy matrix. In this case, fracture toughness can be greatly improved, up to 3‐times if the chemical composition of the microparticles was wisely chosen, without significantly reducing the thermal properties.
62.
Jacques Harvent Benjamin Coudrin Ludovic Brèthes Jean-José Orteu Michel Devy 《Machine Vision and Applications》2013,24(8):1645-1659
Structured light methods achieve 3D modelling by observing with a camera system, a known pattern projected on the scene. The main drawback of single projection structured light methods is that moving the projector changes significatively the appearance of the scene at every acquisition time. Classical multi-view stereovision approaches based on the appearance matching are then not useable. The presented work is based on a two-cameras and one single slide projector system embedded in a hand-held device for industrial applications (reverse engineering, dimensional control, etc). We propose a method to achieve multi-view modelling for camera pose and surface reconstruction estimation in a joint process. The proposed method is based on the extension of a stereo-correlation criterion. Acquisitions are linked through a generalized expression of local homographies. The constraints brought by this formulation allow an accurate estimation of the modelling parameters for dense reconstruction of the scene and improve the result when dealing with detailed or sharp objects, compared to pairwise stereovision methods. 相似文献
63.
In this paper, we analyze the differences, similarities and complementariness which exist between two major domains of nowadays
information security: intrusion detection on one hand, virology and anti-viruses technologies on the other hand. This analysis
is built from two points of view. First, we compare, through the definitions that have been proposed by researchers of the
two communities, the goals that are actually pursued in each domain. Then, we compare the techniques that have been developed
to reach these goals. In the conclusion, we summarize our analysis and suggest that alert correlation is one way to make the
two fields cooperate. 相似文献
64.
Florent Monestier Jean-Jacques Simon Philippe Torchio Ludovic Escoubas Franois Flory Sandrine Bailly Remi de Bettignies Stephane Guillerez Christophe Defranoux 《Solar Energy Materials & Solar Cells》2007,91(5):405-410
We have investigated the short-circuit current density of organic solar cells based on poly (3-hexylthiophene)(P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. In order to model charge collection efficiencies with respect to short circuit density in such blends, a full optical modeling of the cell is performed. From the distribution of the electromagnetic field, we compute the rate of exciton generation. This exciton generation rate is used as input in the transport equations of holes and electrons. Charge densities at steady state are obtained as solutions are used for computing short-circuit current densities generated in the cell. The dependence of short-circuit current densities versus the thickness of the blend is analyzed and compared with our experimental data and with data extracted from the literature. 相似文献
65.
Briquet L Staelens N Leherte L Vercauteren DP 《Journal of molecular graphics & modelling》2007,26(1):104-116
The [3]rotaxane synthesised as a single isomer constituted of two cyclodextrins (CDs) and an azobenzene chain [M.R. Craig, T.D.W. Claridge, M.G. Hutchings, H.L. Anderson, Synthesis of a cyclodextrin azo dye [3]rotaxane as a single isomer, Chem. Commun. 16 (1999) 1537-1538] has been investigated using molecular mechanics (MM) and dynamics (MD) with the MM3 force field in order to evaluate the stability of various configurations of the complex in the isolated and solvated states. The influence of the blocking groups and the presence of energy barriers along the azo chain were first investigated through the calculation of an energy profile. It revealed that the CD could translate along the chain at room temperature without any decomplexation. Next, MD simulations of three different types of configurations, i.e., head-to-head, head-to-tail, and tail-to-tail, of the [3]rotaxane were carried out. The non-solvated phase simulations showed structures with the CDs close to each other while the solvated ones showed structures with CDs separated by larger distances. This separation occurs due to the solute-solvent interactions. When the systems are in isolated state, the observed structure of the complexes are less stable due to an unfavourable arrangement of the hydroxyls groups of the adjacent CD faces. When considering solvation, energies of the three configurations are roughly identical due to the large distance between the faces of the CDs. 相似文献
66.
The effective mechanical properties of a polyurethane adhesive (oligoetherdiol, ‐triol, MDI) in gold joints (bond line thickness, dP = 35–550 µm) are studied in the linear deformation range by dynamic mechanical analysis in shear mode. These properties depend on dP: thin ones possess a higher dynamic glass transition temperature and show a narrower glass transition than the thick ones. The storage modulus rises with decreasing dP for the rubbery plateau. The results attest mechanical interphases in the polyurethane with increased crosslink density and reduced cooperative mobility than in bulk. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42058. 相似文献
67.
Schull G Douillard L Fiorini-Debuisschert C Charra F Mathevet F Kreher D Attias AJ 《Nano letters》2006,6(7):1360-1363
A two-dimensional molecular sieve has been realized. It consists of a host matrix of molecularly engineered building blocks self-assembled at the liquid-solid interface. The simultaneous size- and shape-dependent dynamics of different guest molecules is observed in situ, in real time with submolecular resolution using a scanning tunneling microscope both at the liquid-solid interface and under vacuum. The temperature-dependent dynamics reveals that the diffusion proceeds through thermally activated channeling between single-molecule surface cavities. 相似文献
68.
Tunable acousto-optic spectral imager for atmospheric composition measurements in the visible spectral domain 总被引:1,自引:0,他引:1
E Dekemper N Loodts B Van Opstal J Maes F Vanhellemont N Mateshvili G Franssens D Pieroux C Bingen C Robert L De Vos L Aballea D Fussen 《Applied optics》2012,51(25):6259-6267
We describe a new spectral imaging instrument using a TeO2 acousto-optical tunable filter (AOTF) operating in the visible domain (450-900?nm). It allows for fast (~1 second), monochromatic (FWHM ranges from 0.6?nm at 450?nm to 3.5?nm at 800?nm) picture acquisition with good spatial resolution. This instrument was designed as a breadboard of the visible channel of a new satellite-borne atmospheric limb spectral imager, named the Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere (ALTIUS), that is currently being developed. We tested its remote sensing capabilities by observing the dense, turbulent plume exhausted by a waste incinerator stack at two wavelengths sensitive to NO2. An average value of 6.0±0.4×1017 molecules?cm-2 has been obtained for the NO2 slant column density within the plume, close to the stack outlet. Although this result was obtained with a rather low accuracy, it demonstrates the potential of spectral imaging by using AOTFs in remote sensing. 相似文献
69.
70.
Emilien Buet Jean-Baptiste Dubois Patrick Olier Ludovic Thilly Florence Lecouturier Pierre-Olivier Renault 《International Journal of Material Forming》2012,5(2):121-127
The structure refinement is a challenge for conductors used for the winding of resistive coils producing non-destructive pulsed magnetic fields over 80T. These nanocomposite conductors composed of a conducting multiscale Cu matrix embedding Nb reinforcing nanofilaments are usually manufactured by using a Severe Plastic Deformation (SPD) process based on hot extrusion, accumulative cold drawing and bundling (ADB) steps [Thilly et al. Philos Mag A 82:925, 2002]. Equal-channel angular extrusion (ECAE) is investigated here as an alternative route since it may provide faster refinement to obtain the ultrafine structure needed for optimized electrical and mechanical properties of the conductors. Therefore, copper-niobium specimens obtained by hot extrusion were processed by ECAE at room temperature. The specific die of the ECAE tool used here is constituted by a round channel with three angles corresponding to a total equivalent strain of about 2.5. Deformed samples were examined by optical microscopy and characterized by hardness profiles and x-ray diffraction (texture pole figures). After one ECAE-pass, the shape of the samples is modified but no trace of damage appeared at the Cu-Nb interfaces. An increase of the hardness values localized in the copper matrix is revealed whereas the hardness of the niobium remains unchanged. Prior to ECAE, the hot extrusion process induced a fibre texture for both copper and niobium. Two fibre texture components were observed for copper: <111> and <200>. A single <110> fibre texture component is evidenced for the niobium. After ECAE a significant variation of the texture is observed in relation with the strong shear induced by this process. 相似文献