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91.
Fractional derivatives are well suited to describe wave propagation in complex media. When introduced in classical wave equations, they allow a modeling of attenuation and dispersion that better describes sound propagation in biological tissues. Traditional constitutive equations from solid mechanics and heat conduction are modified using fractional derivatives. They are used to derive a nonlinear wave equation which describes attenuation and dispersion laws that match observations. This wave equation is a generalization of the Westervelt equation, and also leads to a fractional version of the Khokhlov-Zabolotskaya-Kuznetsov and Burgers' equations. 相似文献
92.
Estruch T Jaeck J Pardo F Derelle S Primot J Pelouard JL Haidar R 《Optics letters》2011,36(16):3160-3162
We investigate the strong electromagnetic coupling that settles in dual metallic grating structures. This coupling is evidenced to lead to a perfect optical extinction in the transmission spectrum. The behavior of this perfect extinction that strongly depends on the longitudinal space and the lateral displacement between the two gratings can be explained by a simple model that describes the interference between a propagating mode and a couple of evanescent modes. The results show that the electromagnetic transmission of the structure can be tuned by controlling the position of this perfect transmission extinction and thus pave the way to new types of infrared tunable filters. 相似文献
93.
94.
Fabrice Gritti Irene Leonardis David Shock Paul Stevenson Andrew Shalliker Georges Guiochon 《Journal of chromatography. A》2010,1217(10):1589-1603
The performance of the new Kinetex-C18 column was investigated. Packed with a new brand of porous shell particles, this column has an outstanding efficiency. Once corrected for the contribution of the instrument extra column volume, the minimum values of the reduced plate heights for a number of low molecular weight compounds (e.g., anthracene and naphtho[2,3-a]pyrene) were between 1.0 and 1.3, breaking the legendary record set 3 years ago by Halo-C18 packed columns. The liquid-solid mass transfer of proteins (e.g., insulin and lyzozyme) is exceptionally fast on Kinetex-C18 much faster than on the Halo-C18 column. The different contributions of dispersion and mass transfer resistances to the column efficiency were determined and discussed. The possible reasons for this extremely high column efficiency are discussed. 相似文献
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97.
Pierre Gosselin Hervé Mohrbach 《The European Physical Journal C - Particles and Fields》2011,71(9):1739
The semiclassical approximation for the Hamiltonian of Dirac particles interacting with an arbitrary gravitational field is
investigated. The time dependence of the metric leads to new contributions to the in-band energy operator in comparison to
previous works in the static case. In particular we find a new coupling term between the linear momentum and the spin, as
well as couplings that contribute to the breaking of the particle–antiparticle symmetry. 相似文献
98.
Mathematical justifications are given for a simulation technique of multivariate non-Gaussian random processes and fields based on Rosenblatt's transformation of Gaussian processes. Different types of convergences are given for the approaching sequence. Moreover an original numerical method is proposed in order to solve the functional equation yielding the underlying Gaussian process autocorrelation function. 相似文献
99.
Candice Botuha Fabrice Chemla Franck Ferreira Julien Louvel Alejandro Pérez-Luna 《Tetrahedron: Asymmetry》2010,21(9-10):1147-1153
The stereoselective synthesis of alkynyl 1,2-amino alcohols by the addition of 3-chloro- and 3-methoxymethoxy- allenylzincs to chiral tert-butylsulfinylimines is described. The methodology is applicable to the preparation of alkynyl 2-amino-1,3-diols (O,N,O stereotriads) using α-alkoxy tert-butylsulfinylimines as chiral starting materials. The scope and limitations of the methodology along with recent applications to the efficient asymmetric syntheses of natural and/or bioactive alkaloids and polyhydroxylated alkaloids are presented. 相似文献
100.