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11.
Non-contact handling in microassembly: Acoustical levitation 总被引:1,自引:0,他引:1
Microassembly is currently of the utmost importance in industry. Nevertheless, the classical assembly processes are no longer usable for very small components, typically ranging from 10 m to 10 mm, since usually neglected surface forces disturb the handling task by inducing adhesion between the component and the gripper. A promising alternative to tackle surface forces consists in levitating the handled component. The various advantages of this contactless handling method are reviewed here and justify the choice of this approach. Consequently, the numerous physical principles suitable for contactless handling are briefly described together with their limitations. The evaluation shows that acoustic levitation is best fitted in the case of microassembly. A classification of literature applications is presented hereafter with special focus on acoustic levitation. Finally, the most common models of acoustical levitation are inspected in a general way. The described models come within the scope of non-linear acoustics. 相似文献
12.
Pierre Darcy Patrick Da Costa Henry Mellotte Jean-Michel Trichard Grald Djga-Mariadassou 《Catalysis Today》2007,119(1-4):252-256
To comply with the new regulations on particulate matter, car manufacturers more and more commonly use diesel particulate filters (DPF). The working of these systems needs to periodically burn soot that has been accumulated during the loading of the DPF. This paper describes the kinetics of the non-catalytic and catalytic oxidation of real diesel soot with oxygen. From these experiments, mechanisms for catalyzed and non-catalyzed soot oxidation have been proposed. 相似文献
13.
Pierre Hadaya 《Electronic Commerce Research》2006,6(2):173-185
Based on the literature dealing with the diffusion of innovation and with information systems, and building on the emerging
concepts in electronic commerce (e-commerce), this paper aims at assessing the influence of various factors on firms’ future
level of use of electronic marketplaces (e-marketplaces). This theoretical model is tested on data collected from 1,200 senior
managers in Canadian firms. Findings indicate that a firm’s past experience in e-commerce, as well as the factors relating
to its business relationships ultimately affect its future use of e-marketplaces. Results of TOBIT regressions also show that
the complexity of sophisticated e-commerce implementations is negatively correlated with the future level of use of e-marketplaces,
and that consultants and other experts play an essential role in encouraging and facilitating the use of this new type of
electronic platform. Finally, our survey data demonstrate that the relative influence of some determinants differs according
to the firms’ size.
Pierre Hadaya is an assistant professor of MIS at the Faculté d’administration of the Université de Sherbrooke (Canada). He holds a Ph.D.
in Management of Technology from the école Polytechnique de Montréal. His research interests lie at the intersection of information
technology management, business strategy and interorganizational design. 相似文献
14.
Bissessur H. Charlet G. Gohin E. Simonneau C. Pierre L. Idler W. 《Electronics letters》2003,39(2):192-193
By transmitting 40 channels over 300 km of TeraLight fibre, it is shown that optical differential phase shift keying can be used in 100 GHz-spaced 40 Gbit/s systems, with direct detection and a simple receiving filter. Chromatic dispersion tolerance around 300 ps/nm is also measured, compared to 70 ps/nm for NRZ. 相似文献
15.
Studied the development of the recognition of emotional facial expressions in children and of the factors influencing recognition accuracy. 80 elementary school students (aged 5–8 yrs) were asked to identify the emotions expressed in a series of facial photographs. Recognition performances were analyzed in relation to the type of emotion expressed (i.e., happiness, fear, anger, surprise, sadness, or disgust) and the intensity of the emotional expression. Age differences were determined. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
This paper gives an account of ‘left’ and ‘progressive’ economic development politics and policy in Sheffield and Chicago in the early 1980s. The origins of these policies in activist work and grassroots organizing, and the leadership of John Benington and David Blunkett in Sheffield and of Robert Mier and Harold Washington in Chicago are characterized and briefly compared. 相似文献
17.
18.
VF Ferrario L Marzona C Sforza A De Pol A Miani AE Bertelli A Forabosco 《Canadian Metallurgical Quarterly》1993,15(1):37-48
A model of human neonatal ovary is presented, derived from morphometric, evaluations carried out on left ovaries removed from five full-term neonates with a 46, XX karyotype, free from malformations of the genital apparatus. According to this model, the gonad can be represented by a triaxial ellipsoid with a central medullary core surrounded by a cortical stratum of constant thickness. The germinal population, consisting of follicles and primitive cortical tissue, occupies the cortex, intermingled with the interstitium or stroma. In the cortex it is then possible to describe an outer layer formed by primitive cortical tissue, and an inner portion occupied by follicles. The primary and secondary follicles fill the portion near the medulla and the primordial ones are contained in the middle and outer zones. Since the variability observed among ovaries is slight, we can propose a mean model of neonatal ovary in which the spatial relationships among the different components, the total number of follicles and their position in the cortex can be calculated. 相似文献
19.
P Cermák M Polácek M Soucek J Seget'a J Jusková M Hanáková 《Canadian Metallurgical Quarterly》1995,60(6):298-300
Between October 1994 and the end of February 1995 115 patients were included in our programme. In these patients we monitored 141 cycles, performed 128 punctures and 100 ET. In 14 instances (9.2%) the cycle was abolished. By puncture of 1468 follicles 1370 oocytes were obtained which corresponded to a recovery rate of 93.3%. On average by aspiration 11.9 oocytes per patient were obtained. From the total number of acquired oocytes 54.6% were fertilized and 43.5% divided. Of 596 embryos 290 were transferred and the remainder was vitrified. A total of 17 clinical pregnancies were achieved, incl. 5 which terminated by abortion, the remainder proceeds. The authors are aware that they present a relatively small group during a short period of time, and thus the first results of the centre cannot be presented as a current standard. Despite this the results permit some optimism for the future and indicate a certain amount of standardization of the authors' clinical and laboratory work. 相似文献
20.
Studied the social reputations of elementary school children. Ss were 76 2nd-grade (mean age 7.5 yrs), 71 3rd-grade (mean age 8.5 yrs), and 83 4th-grade students (mean age 9.7 yrs). Using the peer nomination technique, Ss were assessed collectively on 8 dimensions requiring both social and academic judgments. A cluster analysis was performed to identify groups with different sociometric profiles. Correlations between peer evaluations and teacher evaluations of Ss' social reputations were determined. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献