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131.
Nanoscale Microstructural and Chemical Analysis of SiO2–Zn1−xAlxO Nanocomposites: Towards a Better Understanding of Si and Al Substitution in ZnO 下载免费PDF全文
Matthieu Gilbert Celine Byl David Berardan Alexandre Gloter Nita Dragoe François Vurpillot 《Journal of the American Ceramic Society》2015,98(12):3948-3955
In this study, we report on the microstructure of SiO2‐coated Al‐doped ZnO nanoparticles densified by spark plasma sintering(SPS), using a multiscale approach. Our observations show that it is possible to successfully prepare dense pellets while keeping the nanostructure with well‐defined Si‐rich grain boundaries. Although a very limited partial solubility of Si in the ZnO matrix has been observed, Si is mostly concentrated at the grain boundaries. More surprisingly, we evidenced some areas with nanoscale inhomogeneity of the Al concentration, which can locally strongly exceed the average composition of the matrix. It could explain the apparent discrepancy observed in the literature between the simultaneous presence of ZnAl2O4 in Al‐doped ZnO, which should be the signature of the doping level exceeding the solubility limit, and the concentration of carriers that still depends on the nominal Al concentration in ZnO even in the presence of ZnAl2O4. 相似文献
132.
Systematic Control of Structural Changes in GeO2 Glass Induced by Femtosecond Laser Direct Writing 下载免费PDF全文
Taiga Asai Yasuhiko Shimotsuma Torataro Kurita Atsushi Murata Sho Kubota Masaaki Sakakura Kiyotaka Miura Francois Brisset Bertrand Poumellec Matthieu Lancry 《Journal of the American Ceramic Society》2015,98(5):1471-1477
We report the structural changes inside germania glass induced by femtosecond laser pulses. Inspection by polarization microscopy and secondary electron microscopy indicate that the periodic nanostructures consist of oxygen defects such as ODCs (oxygen deficient centers) and NBOHCs (nonbridging oxygen hole centers) for laser pulse energy less than 0.2 μJ. However, the glass network was dissociated and O2 molecules were generated for laser pulse energy greater than 0.4 μJ. Two different structural changes, form‐birefringence and dissociation, were induced in GeO2 glass, depending on the laser pulse energy. The form‐birefringence exhibited by the nanogratings in GeO2 glass is larger than that in SiO2 glass for pulse energy less than 0.2 μJ, as the density of nanovoids enclosed by ODCs in GeO2 glass is higher than that in SiO2 glass. Arrhenius plots of the phase retardation caused by the nanogratings in GeO2 and SiO2 indicate that the oxygen defects are relaxed at a temperature 100°C above the glass‐transition temperature. 相似文献
133.
Werner S Eibl R Lettenbauer C Röll M Eibl D De Jesus M Zhang X Stettler M Tissot S Bürki C Broccard G Kühner M Tanner R Baldi L Hacker D Wurm FM 《Chimia》2010,64(11):819-823
Innovative mixing principles in bioreactors, for example using the rocking of a platform to induce a backwards and forwards 'wave', or using orbital shaking to generate a 'wave' that runs round in a cylindrical container, have proved to be successful for the suspension cultures of cells, especially when combined with disposable materials. This article presents an overview of the engineering characteristics when these new principles are applied in bioreactors, and case studies covering scales of operation from milliliters to 1000 liters. 相似文献
134.
Matthieu Labat Monika Woloszyn Geraldine Garnier Gilles Rusaouen Jean Jacques Roux 《Solar Energy》2012,86(9):2549-2560
This paper is based on the study of an experimental wooden-framed house, equipped with a ventilated cladding, located in France. The focus is on investigating the heat transfer taking place in the ventilated air gap behind the cladding and on estimating their impact on heat transfer in the insulated part of the walls.Preliminary CFD simulation made it possible to describe the airflow in the ventilated air gap when buoyancy was acting as the main driving force. It was found that the airflow velocity could reach 0.8 m s?1, when exposed to 570 W m?2 solar irradiance. This was verified experimentally. A correlation to assess airflow rate in the air gap behind the cladding has been developed based on temperature differences and on experimental conclusions. The correlation is adapted to energy performance simulation and efficiently represents the average cavity airflow at different height for various irradiance and temperature conditions. 相似文献
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137.
Combining visual dictionary, kernel-based similarity and learning strategy for image category retrieval 总被引:1,自引:0,他引:1
Philippe Henri Gosselin Matthieu Cord Sylvie Philipp-Foliguet 《Computer Vision and Image Understanding》2008,110(3):403
This paper presents a search engine architecture, RETIN, aiming at retrieving complex categories in large image databases. For indexing, a scheme based on a two-step quantization process is presented to compute visual codebooks. The similarity between images is represented in a kernel framework. Such a similarity is combined with online learning strategies motivated by recent machine-learning developments such as active learning. Additionally, an offline supervised learning is embedded in the kernel framework, offering a real opportunity to learn semantic categories. Experiments with real scenario carried out from the Corel Photo database demonstrate the efficiency and the relevance of the RETIN strategy and its outstanding performances in comparison to up-to-date strategies. 相似文献
138.
Interpenetrating polymer networks (IPNs) combining polyisobutene (PIB) and poly(methyl methacrylate) (PMMA) networks were prepared using a in situ strategy. PIB networks were formed by isocyanate—alcohol addition between the hydroxyl end groups of telechelic dihydroxy-polyisobutene and an isocyanate cross-linker, catalyzed by dibutyltindilaurate (DBTDL). PMMA networks were obtained from free-radical co-polymerization of methyl methacrylate (MMA) with ethylene glycol bismethacrylate (EGDM) in the presence of dicyclohexyl peroxydicarbonate (DCPD) as the initiator. The synthesis of each network during the IPN formation was followed by FTIR spectroscopy. The highest degree of interpenetration is obtained by forming the PIB network first. The corresponding transparent IPNs exhibit two mechanical relaxation temperatures as determined by Dynamic mechanical thermal analysis (DMTA), corresponding to those of PMMA and PIB enriched phases. Mechanical properties of PIB networks are tremendously improved by the presence of PMMA network in such IPN architecture. 相似文献
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140.
汽车安全气囊传感器市场发展趋势 总被引:1,自引:0,他引:1
Matthieu Reze 《电子设计应用》2006,(8):93-94
自20世纪70年代出现以来至今,安全气囊系统有了很大的发展,目前乘客/前排安全气囊已经在全球范围内成为新生产汽车的标准配置。根据市场报告,在一些新产品特性的推动下,如保护头部、胸部及膝盖的侧面气囊以及智能乘客检测系统等,到2010年,全球总的安全气囊应用数量将达到1.8亿个。为了达到政府或碰撞试验机构(如EuroNCAP)的最高安全性要求,当前高端汽车上用于探测碰撞的加速度传感器的数量已经达到6个,并且仍有增加趋势。而加速度传感器的设计者们也正在采用新材料及新技术来保持整个安全气囊系统的市场竞争力。基于MEMS(微机电系统)的… 相似文献