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排序方式: 共有458条查询结果,搜索用时 187 毫秒
451.
R. Chaplin D. MacManus F. Leopold T. Gauthier B. Martinez T. Birch 《Experiments in fluids》2011,50(2):491-507
Aerodynamic interference between high-speed slender bodies can detrimentally affect the force and moment characteristics.
This is investigated through a wind tunnel study using pressure sensitive paint and force measurements on a receiver body
placed adjacent to a generator body. The aim of this paper is to understand both the force and moment changes as well as the
underlying aerodynamics of the interference loads which are induced by the disturbance flowfield. The impact of receiver incidence
and the strength of the disturbance field are also assessed. The observed interference loads primarily depend on a complex
balance of static pressure footprints and tend to be bespoke to each configuration. As a result, overall trends are difficult
to extract, but in general the magnitude of the interference loads increases when the receiver is at incidence and also when
the strength of the imposed disturbance flowfield increases. 相似文献
452.
Abstract Ultrasonic (70 W, 20 kHz) solution (2% THF) degradations of polystyrene (PS), poly(α-methylstyrene) (PαMeS), poly(p-isopropyl α-methylstyrene) (PpiPrαMeS), poly(p-chlorostyrene) (PpCIS), poly(p-bromostyrene) (PpBrS), and poly(p-methoxystyrene) (PpOMeS) have been carried out in tetrahydrofuran at 27° C. The average number of chain scissions S (where S = [(M n)0/(M n)t] - 1), computed from the overall values of [(M n)0 and (M n)t, were found to be different from those of S' (where S' = α([(M n)0/(M n)t] - 1)) based on the component (only that part of the polymer which is involved in degradation) data of the weight fraction (α), (M n)0, and (M n)t), S' for polystyrene and substituted polystyrene follows the order PS gt; PpCIS gt; PpiPrαMeS gt; PpBrS gt; PpOMeS gt; PαMeS. In the case of PS where degradations were also carried out at -20°C, lowering of the temperature increased the weight fraction of polymer degraded as well as S. Based on the viscosity and GPC data, it is concluded that the ultrasonic solution degradation of PS does not lead to branched polymers. 相似文献
453.
Sébastien Gauthier Nikolay Vologdin Sylvain Achelle Alberto Barsella Bertrand Caro Françoise Robin-le Guen 《Tetrahedron》2013
This paper presents the synthesis of a series of push–pull and quadrupolar π-conjugated structures incorporating pro-aromatic methylenepyran electron-donor groups and various electron-attracting groups. Some of the methylenepyran derivatives were oxidized by I2 to give, after reduction by Na2S2O3, bismethylenepyran compounds via successive steps. 相似文献
454.
Sound field reproduction has applications in music reproduction, spatial audio, sound environment reproduction, and experimental acoustics. Sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. The room response thus reduces the quality of the physical sound field reproduction by WFS. In recent research papers, adaptive wave field synthesis (AWFS) was defined as a potential solution to compensate for these quality reductions from which WFS objective performance suffers. In this paper, AWFS is experimentally investigated as an active sound field reproduction system with a limited number of reproduction error sensors to compensate for the response of the listening environment. Two digital signal processing algorithms for AWFS are used for comparison purposes, one of which is based on independent radiation mode control. AWFS performed propagating sound field reproduction better than WFS in three tested reproduction spaces (hemianechoic chamber, standard laboratory space, and reverberation chamber). 相似文献
455.
456.
Lucie Blondeau Suzy Surble Eddy Foy Hicham Khodja Magali Gauthier 《Journal of Energy Chemistry》2021,(4):124-128
A composite In-Pb:carbon was successfully synthetized by a two-step mechanochemical synthesis in order to obtain an adequate particles size and structure to investigate the electrochemical reactivity of the In-Pb solid solution towards Mg.A potential synergetic coupling of electroactive elements In and Pb was examined using electrochemical and ex situ X-ray diffraction analyses.The potential profile of the solid solution indicates the formation of Mg2Pb and Mg In.However,the diffraction study suggests a peculiar electrochemically-driven amorphization of Mg In during the magnesiation,in strong contrast to Mg In crystallization in In-based and In Bi-based electrodes reported in the literature.Combining In and Pb favors the amorphization of Mg In and a high first magnesiation capacity of about 550 m Ah g-1,but is thereafter detrimental to the material’s reversibility.These results emphasize the possible influence of electrochemically-driven amorphization and crystallization processes on electrochemical performance of battery materials. 相似文献
457.
Xiaoxuan Yang Shreya Mukherjee Thomas O'Carroll Prof. Yang Hou Prof. Meenesh R. Singh Prof. Joseph A. Gauthier Prof. Gang Wu 《Angewandte Chemie (International ed. in English)》2023,62(10):e202215938
Unrestrained anthropogenic activities have severely disrupted the global natural nitrogen cycle, causing numerous energy and environmental issues. Electrocatalytic nitrogen transformation is a feasible and promising strategy for achieving a sustainable nitrogen economy. Synergistically combining multiple nitrogen reactions can realize efficient renewable energy storage and conversion, restore the global nitrogen balance, and remediate environmental crises. Here, we provide a unique aspect to discuss the intriguing nitrogen electrochemistry by linking three essential nitrogen-containing compounds (i.e., N2, NH3, and NO3−) and integrating four essential electrochemical reactions, i.e., the nitrogen reduction reaction (N2RR), nitrogen oxidation reaction (N2OR), nitrate reduction reaction (NO3RR), and ammonia oxidation reaction (NH3OR). This minireview also summarizes the acquired knowledge of rational catalyst design and underlying reaction mechanisms for these interlinked nitrogen reactions. We further underscore the associated clean energy technologies and a sustainable nitrogen-based economy. 相似文献
458.
A.M.C. Dawes D.J. Gauthier S. Schumacher N.H. Kwong R. Binder A.L. Smirl 《Laser \u0026amp; Photonics Reviews》2010,4(2):221-243
We review recent theoretical and experimental efforts toward developing an all‐optical switch based on transverse optical patterns. Transverse optical patterns are formed when counterpropagating laser beams interact with a nonlinear medium. A perturbation, in the form of a weak switch beam injected into the nonlinear medium, controls the orientation of the generated patterns. Each state of the pattern orientation is associated with a state of the switch. That is, information is stored in the orientation state. A realization of this switch using a warm rubidium vapor shows that it can be actuated by as few as 600 ± 40 photons with a response time of 5 µs. Models of nonlinear optical interactions in semiconductor quantum wells and microresonators suggest these systems are also suitable for use as fast all‐optical switches using this same conceptual design, albeit at higher switching powers. 相似文献