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Caen, France

Beloufa A.,Crismat
Journal of Heat Transfer | Year: 2012

Automotive connectors in modern car generations are submitted to high current; this can cause many problems and requires the minimization of their electrical contact resistances. The new major contribution of this work is the optimization by finite element method of contact resistance, contact temperature, design, and mechanical stress of sphere/plane contact samples. These contact samples were made with recent high-copper alloys and were subjected to indentation loading. Experimental tests were carried out in order to validate the developed numerical model and to select the material which presents a low contact temperature and contact resistance. Another model with multipoint contacts was developed in order to minimize electrical contact resistance and contact temperature. Shape optimization results indicate that the volume of contact samples was reduced by 12. The results show also for the model with multipoint contacts that the contact resistance was reduced by 41, contact temperature by 22 and maximum Von Mises stress by 49. These several gains are more interesting for the connector designers. © 2012 American Society of Mechanical Engineers.

Jorel C.,National Engineering School of Caen | Colder H.,Crismat | Galdi A.,National Engineering School of Caen | Galdi A.,CNR Institute of Neuroscience | And 2 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2012

We report the growth of epitaxial Pb(Zr0.54Ti0.46)O3 (PZT) thin films on yttria-stabilized zirconia buffered silicon substrates by pulsed laser deposition. We demonstrate a full in plane epitaxy of the buffer layer, showing a RMS roughness of less than 0.3 nm for a 120 nm thick layer. This buffer layer allows the growth of fully (110) textured oxide conducting SrRuO3 and subsequent functional oxide layers. Here the Pb(Zr,Ti)O3 oxide was chosen to demonstrate its possible integration in piezoelectric microelectromechanical systems on silicon. © Published under licence by IOP Publishing Ltd.

Prou N.,Crismat | Riviere F.,Crismat | Berland C.,University Paris Est Creteil
Conference Proceedings - 9th Conference on Ph. D. Research in Microelectronics and Electronics, PRIME 2013 | Year: 2013

The LInear amplification with Nonlinear Component transmitter is a high power efficient architecture for radio communication systems. Nevertheless, this architecture is sensitive to mismatches between the two paths and its efficiency performances are dependent on the power amplification stage topology. Additively, careful attention has to be paid to baseband performances in terms of sampling rate, Digital to Analog Converters (DACs) resolution, reconstruction filter bandwidth. In this paper, we present the specification of the reconstruction filters for a single carrier WCDMA 3GPP base station transmitter and this, according to the Power Amplifier (PA) class (switched mode (SMPA) or AB class). We address the impact of the class of the PAs on the overall performances and on the reconstruction filters specifications. Admissible time delays and gain mismatches between the two paths will also be quantified. © 2013 IEEE.

Thuault A.,Crismat | Eve S.,Crismat | Bazin J.,Crismat | Charlet K.,IFMA | And 3 more authors.
Materiaux et Techniques | Year: 2011

In this paper we seeked for correlation among the biocomposition, morphological parameters and mechanical properties of flaw fibre. Seven varieties among the most frequently cultivated in Normandy are examined. Biocomposition analyses have shown no significant differences between the different varieties while noticeable differences have been evidenced between the varieties for mechanical properties, and these are comparable to the dispersion within a given variety. Thus, the differences in mechanical properties among these varieties are not ascribed to morphological or biocomposition parameters. © 2011 EDP Sciences.

Thuault A.,Crismat | Domenges B.,Presto Engineering | Hervas I.,Crismat | Hervas I.,Arts et Metiers ParisTech | Gomina M.,Crismat
Cellulose | Year: 2015

The development of the use of flax fibre as reinforcement of eco-friendly composite materials requires a good knowledge of its hydrothermal and mechanical behaviours. To this end the fibre internal structure must be finely investigated. Transmission electron microscopy was used to analyse the morphology of the fibre cell walls in terms of the arrangement of the layers and their thickness. Thus, an alternative eco-friendly staining method, based on oolong tea extract was successfully implemented. The results reveal an arrangement at the nanoscale slightly different from the classical four layer model encountered in the literature: the inner layer includes three to four sub-layers. The cell walls comprises two outer layers of relative thickness of about 10 %, a middle layer of about 70 % and a group of thinner layers (called sub-layers) that are contiguous to the lumen with relative thickness of about 20 %. © 2015, Springer Science+Business Media Dordrecht.

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