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排序方式: 共有237条查询结果,搜索用时 15 毫秒
41.
Bachelot R Lerondel G Blaize S Aubert S Bruyant A Royer P 《Microscopy research and technique》2004,64(5-6):441-452
This report presents the Apertureless Scanning Optical Near-Field Microscope as a powerful tool for the characterization of modern optoelectronic and photonic components with sub-wavelength resolution. We present an overview of the results we obtained in our laboratory over the past few years. By significant examples, it is shown that this specific probe microscopy allows for in situ local quantitative study of semiconductor lasers in operation, integrated optical waveguides produced by ion exchange (single channel or Y junction), and photonic structures. 相似文献
42.
We report operation and characterization of a lab-assembled single-photon detector based on commercial silicon avalanche photodiodes (PerkinElmer C30902SH, C30921SH). Dark count rate as low as 5 Hz was achieved by cooling the photodiodes down to -80 °C. While afterpulsing increased as the photodiode temperature was decreased, total afterpulse probability did not become significant due to detector's relatively long deadtime in a passively-quenched scheme. We measured photon detection efficiency >50% at 806 nm. 相似文献
43.
Vladimir Pletser Sebastien Rouquette Ulrike Friedrich Jean-Francois Clervoy Thierry Gharib Frederic Gai Christophe Mora 《Microgravity science and technology》2016,28(6):587-601
Aircraft parabolic flights repetitively provide up to 23 seconds of reduced gravity during ballistic flight manoeuvres. Parabolic flights are used to conduct short microgravity investigations in Physical and Life Sciences and in Technology, to test instrumentation prior to space flights and to train astronauts before a space mission. The use of parabolic flights is complementary to other microgravity carriers (drop towers, sounding rockets), and preparatory to manned space missions on board the International Space Station and other manned spacecraft, such as Shenzhou and the future Chinese Space Station. After 17 years of using the Airbus A300 ZERO-G, the French company Novespace, a subsidiary of the ’Centre National d’Etudes Spatiales’ (CNES, French Space Agency), based in Bordeaux, France, purchased a new aircraft, an Airbus A310, to perform parabolic flights for microgravity research in Europe. Since April 2015, the European Space Agency (ESA), CNES and the ‘Deutsches Zentrum für Luft- und Raumfahrt e.V.’ (DLR, the German Aerospace Center) use this new aircraft, the Airbus A310 ZERO-G, for research experiments in microgravity. The first campaign was a Cooperative campaign shared by the three agencies, followed by respectively a CNES, an ESA and a DLR campaign. This paper presents the new Airbus A310 ZERO-G and its main characteristics and interfaces for scientific experiments. The experiments conducted during the first European campaign are presented. 相似文献
44.
This paper focuses on the detection of small objects—more precisely on vehicles in aerial images—on complex backgrounds such as natural backgrounds. A key contribution of the paper is to show that, in such situations, learning a target model and a background model separately is better than training a unique discriminative model. This contrasts with standard object detection approaches for which objects vs. background classifiers use the same model as well as the same types of visual features for both. The second contribution lies in the manifold learning approach introduced to build these models. The proposed detection algorithm is validated on the publicly available OIRDS dataset, on which we obtain state-of-the-art results. 相似文献
45.
Said Mikki Sebastien Clauzier Muhammad A. Karimi Atif Shamim Yahia M. M. Antar 《国际射频与微波计算机辅助工程杂志》2020,30(11)
The present article proposes and validates a new general design methodology that can be used to automatically find proper positions and orientations of waveguide‐based radiating slots capable of realizing any given radiation beam profile. The new technique combines basic radiation theory and waveguide propagation theory in an analytical model that permits the prediction of the radiation characteristics of generic slots without the need to perform full‐wave numerical solution while completely avoiding using transmission‐line models or the slot impedance method. The analytical model is then used to implement a low‐cost objective function within a global optimization scheme and subsequently deployed to find optimum positions and orientations of clusters of radiating slots cut into the waveguide surface such that any desired beam pattern can be obtained, leading to very efficient and robust beamforming capability that can be applied to dynamic beamforming in real‐time scenarios like MIMO systems. The proposed design method is verified using both full‐wave numerical solution and experiment. 相似文献
46.
Abstract Flying Cities is an artistic installation which generates imaginary cities from the speech of its visitors. Thanks to an original interactive process analysing people's vocal input to create 3D graphics, a tangible correspondence between speech and visuals opens new possibilities of interaction. This cross-modal interaction not only supports our artistic messages, but also aims at providing anyone with a pleasant and stimulating feedback from her/his speech activity. As the feedback we have received when presenting Flying Cities was very positive, our objective is now to cross the bridge between art and a potential application. We believe that it could become a new medium for creativity and a way to visually perceive a vocal performance in the context of the rehabilitation of people with reduced mobility or language impairments. 相似文献
47.
Water-soluble polyaramides have been prepared from 2,5-diaminobenzene-sulphonic-acid activated by TMSCl and terephthalic-acid-chloride. Using this method, we achieved molecular weights of our polymers up to 18,000 g mol−1. Two model compounds were synthesized in order to establish the effect of trimethylsilyl-chloride, which was used as the activating agent for this reaction. The resulting sulphonated poly-aramides were characterized by: inherent viscosity measurements, size exclusion chromatography (SEC), DMA, TGA, flame absorbance atomic spectroscopy (FAAS), NMR spectroscopy and optical polarisation microscopy. In all cases, the polymers were easily soluble in hot water up to concentrations of 20 wt%. Upon cooling lyotropic alignment of molecular aggregates is observed at low polymer concentrations, typically 2–5 wt%. Polymers with low molecular weights do not show this behaviour. Films made from these sulphonated aramide polymers showed good thermal stability, and have interesting mechanical properties. Our results indicate the presence of a structure consisting of molecular aggregates. 相似文献
48.
Ion Iliuta Raul Tahoces Gregory S. Patience Sebastien Rifflart Francis Luck 《American Institute of Chemical Engineers》2010,56(4):1063-1079
Chemical Looping Combustion technology involves circulating a metal oxide between a fuel zone where methane reacts under anaerobic conditions to produce a concentrated stream of CO2 and water and an oxygen rich environment where the metal is reoxidized. Although the needs for electrical power generation drive the process to high temperatures, lower temperatures (600–800°C) are sufficient for industrial processes such as refineries. In this paper, we investigate the transient kinetics of NiO carriers in the temperature range of 600 to 900°C in both a fixed bed microreactor (WHSV = 2‐4 g CH4/h/g oxygen carrier) and a fluid bed reactor (WHSV = 0.014‐0.14 g CH4/h per g oxygen carrier). Complete methane conversion is achieved in the fluid bed for several minutes. In the microreactor, the methane conversion reaches a maximum after an initial induction period of less than 10 s. Both CO2 and H2O yields are highest during this induction period. As the oxygen is consumed, methane conversion drops and both CO and H2 yields increase, whereas the CO2 and H2O concentrations decrease. The kinetics parameter of the gas–solids reactions (reduction of NiO with CH4, H2, and CO) together with catalytic reactions (methane reforming, methanation, shift, and gasification) were estimated using experimental data obtained on the fixed bed microreactor. Then, the kinetic expressions were combined with a detailed hydrodynamic model to successfully simulate the comportment of the fluidized bed reactor. © 2010 American Institute of Chemical Engineers AIChE J, 2010 相似文献
49.
Stoffregen Thomas A.; Villard Sebastien; Kim ChungGon; Ito Kiyohide; Bardy Beno?t G. 《Canadian Metallurgical Quarterly》2009,35(4):1221
The authors asked whether standing posture could be controlled relative to audible oscillation of the environment. Blindfolded sighted adults were exposed to acoustic flow in a moving room, and were asked to move so as to maintain a constant distance between their head and the room. Acoustic flow had direct (source) and indirect (reflected) components. Participants exhibited strong coupling of postural motion with room motion, even when direct information about room motion was masked and was available only in reflected sound. Patterns of hip–ankle coordination closely resembled patterns observed in previous research involving coupling of sway with a visible moving room. The results demonstrate that blindfolded adults can control the dynamics of stance relative to motion of the audible environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.