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21.
C. Sarra‐Bournet S. Poulin K. Piyakis S. Turgeon G. Laroche 《Surface and interface analysis : SIA》2010,42(2):102-109
Time of flight secondary ion mass spectrometry (ToF‐SIMS) is a powerful tool for the surface characterization of plasma‐modified surface. However, the SIMS fragmentation patterns of the resulting surface are quite complex and a full interpretation may be prohibitive. As a result, many studies are turning to multivariate statistical methods to simplify the interpretation. In this study, a principal component analysis (PCA) was used to obtain a more detailed interpretation of the surface modification of polymers by an atmospheric pressure plasma. The dataset was obtained from three polymers with different chemical compositions [namely, polyethylene, polyvinylidene fluoride, and poly(tetrafluoroethylene)], where each material was treated with an atmospheric pressure dielectric barrier discharge (DBD) in an atmosphere composed of different N2/H2 ratios. The results are discussed in terms of the suitability of ToF‐SIMS analysis combined with PCA for the discrimination between the three polymers and the possibility to create a predictive model that would describe the plasma surface modification, independent of the polymer substrate chemical composition. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
22.
Summary In this paper we study the centrifugal pendulum as a torsional vibrations absorber of an engine. A non-autonomous two degrees of freedom mechanical system with viscous-Coulomb damping is considered. The motion equations are written and we analyse for small oscillations of the pendulum, the effect of the non linear damping on the response curves in amplitude. Several numerical examples are ratio and the damping coefficients on the resonance peaks.
This work has been realized within the activities of the Italian Council for the Research, C.N.R., G.N.F.M. 相似文献
Sommario In questo lavoro si studia il pendolo centrifugo come ammortizzatore di vibrazioni torsionali di un motore. Si considera un sistema meccanico non autonomo a due gradi di libertà con dissipazione coulombiana-viscosa. Si scrivono le equazioni del moto e si analizza, per piccole oscillazioni del pendolo, l'effetto dell'attrito non lineare sulle curve di risposta in ampiezza. Vengono presentati numerosi esempi numerici per illustrare l'influenza del rapporto di massa e dei coefficienti di attrito sui picchi di risonanza.
This work has been realized within the activities of the Italian Council for the Research, C.N.R., G.N.F.M. 相似文献
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Sarra Zid Matthieu Zinet Eliane Espuche 《Journal of Polymer Science.Polymer Physics》2019,57(1):51-61
The optimization of polymer barrier properties is currently of crucial importance for a wide range of applications from packaging to building or even energy applications. To meet the requirements of these applications, polymer matrices are often combined with impermeable (nano) fillers. Different nanofiller natures, shapes, and contents have been experimentally used and a large range of barrier materials has been obtained. In the meantime, several numerical approaches have been developed to model gas diffusion properties of nanocomposite materials. However, these approaches often considered bidimensional systems. The aim of this work is to develop 3D Finite Element Model which would be used to predict gas barrier properties of nanocomposites for disk‐shaped nanofillers. The model thus obtained is valid in a wide range of fillers volume fraction values as well as aspect ratios, which makes it possible to go from diluted regimes to semidiluted or even concentrated ones. Furthermore, an analytical equation which describes gas diffusion through nanocomposites films has been built and validated with our finite element modeling model. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 51–61 相似文献
25.
Scott A. Sarra 《Numerical Methods for Partial Differential Equations》2012,28(2):389-401
Gaussian radial basis function (RBF) interpolation methods are theoretically spectrally accurate. However, in applications this accuracy is seldom realized due to the necessity of solving a very poorly conditioned linear system to evaluate the methods. Recently, by using approximate cardinal functions and restricting the method to a uniformly spaced grid (or a smooth mapping thereof), it has been shown that the Gaussian RBF method can be formulated in a matrix free framework that does not involve solving a linear system [ 1 ]. In this work, we differentiate the linear system‐free Gaussian (LSFG) method and use it to solve partial differential equations on unbounded domains that have solutions that decay rapidly and that are negligible at the ends of the grid. As an application, we use the LSFG collocation method to numerically simulate Bose‐Einstein condensates. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 28: 389–401, 2012 相似文献
26.
Long TR Faisal S Maity PK Rolfe A Kurtz R Klimberg SV Najjar MR Basha FZ Hanson PR 《Organic letters》2011,13(8):2038-2041
Soluble, high-load ring-opening metathesis polymerization (ROMP)-derived oligomeric triazole phosphates (OTP) are reported for application as efficient triazolating reagents of nucleophilic species. Utilizing a "Click"-capture, ROMP, release protocol, the efficient and purification-free, direct triazolation of N-, O-, and S-nucleophilic species was successfully achieved. A variety of OTP derivatives were rapidly synthesized as free-flowing solids on a multigram scale from commercially available materials. 相似文献
27.
Applying classical association rule extraction framework on fuzzy datasets leads to an unmanageably highly sized association rule sets. Moreover, the discretization operation leads to information loss and constitutes a hamper towards an efficient exploitation of the mined knowledge. To overcome such a drawback, this paper proposes the extraction and the exploitation of compact and informative generic basis of fuzzy association rules. The presented approach relies on the extension, within the fuzzy context, of the notion of closure and Galois connection, that we introduce in this paper. In order to select without loss of information a generic subset of all fuzzy association rules, we define three fuzzy generic basis from which remaining (redundant) FARs are generated. This generic basis constitutes a compact nucleus of fuzzy association rules, from which it is possible to informatively derive all the remaining rules. In order to ensure a sound and complete derivation process, we introduce an axiomatic system allowing the complete derivation of all the redundant rules. The results obtained from experiments carried out on benchmark datasets are very encouraging. They highlight a very important reduction of the number of the extracted fuzzy association rules without information loss. 相似文献
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Marie-Julie Pintor Corine Jean-Marius Valérie Jeanne-Rose Pierre-Louis Taberna Patrice Simon Jean Gamby Roger Gadiou Sarra Gaspard 《Comptes Rendus Chimie》2013,16(1):73-79
Turbinaria turbinata brown seaweeds were tested as carbon electrode material in symmetric, electrochemical supercapacitors. The electrochemical properties of the carbon materials were characterised for their application as supercapacitors using cyclic voltammetry, galvanostatic charge/discharge method and electrochemical impedance spectroscopic analyses. Our initial results showed that the optimal behaviour was obtained for the sample prepared by pyrolysis at 800 °C. The average surface area of the carbon was 812 m2/g. Electrochemical tests with an organic electrolyte gave the following interesting results: a capacitance of 74.5 F/g, a specific series resistance of 0.5 Ω cm2 and an ionic resistivity of 1.3 Ω cm2. These results show the promising capacitive properties of carbon derived from seaweeds and their application in electrochemical supercapacitors. 相似文献
29.
Scott A. Sarra 《国际流体数值方法杂志》2003,42(3):249-263
The numerical solution of a model describing a two‐dimensional fluidized bed by a Chebyshev super spectral viscosity (SSV) method is considered. The model is in the form of a hyperbolic system of conservation laws with a source term, coupled with an elliptic equation for determining a stream function. The coupled elliptic equation is solved by a finite‐difference method. The mixed SSV/finite‐difference method produces physically shaped bubbles, on a very coarse grid. Fine scale details, which were not present in previous finite‐difference solutions, are present in the solution. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Corentin Rinfray Dr. Guillaume Izzet Prof. Dr. Jean Pinson Dr. Sarra Gam Derouich Dr. Jean‐Jacques Ganem Dr. Catherine Combellas Dr. Frédéric Kanoufi Prof. Dr. Anna Proust 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13838-13846
Polyoxometalates (POMs) are attractive candidates for the rational design of multi‐level charge‐storage materials because they display reversible multi‐step reduction processes in a narrow range of potentials. The functionalization of POMs allows for their integration in hybrid complementary metal oxide semiconductor (CMOS)/molecular devices, provided that fine control of their immobilisation on various substrates can be achieved. Owing to the wide applicability of the diazonium route to surface modification, a functionalized Keggin‐type POM [PW11O39{Ge(p‐C6H4‐C?C‐C6H4‐${{\rm N}{{+\hfill \atop 2\hfill}}}$ )}]3? bearing a pending diazonium group was prepared and subsequently covalently anchored onto a glassy carbon electrode. Electron transfer with the immobilised POM was thoroughly investigated and compared to that of the free POM in solution. 相似文献