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71.
N. Boulaftali N. Ben Sari-Zizi H. Najib G. GranerH. Bürger E.B. MkadmiP. Pracna 《Journal of Molecular Spectroscopy》2002,214(1):35-51
The ν1 (A1, 1578.31 cm−1)/ν4(E, 1615.17 cm−1) Si-D stretching dyad of D3SiF has been studied by FTIR spectroscopy with a resolution of 2.4×10−3 cm−1. Only weak interactions of Coriolis (ΔK=±1, Δ?=±1) and α resonance (ΔK=±2, Δ?=?1) type between ν1 and ν4, and of ? (2,−4) type within ν4, were revealed. However, the v1=1 and v4=1 levels were found to be severely perturbed by the v3=v5=1 (E, 1590.37 cm−1) and v2=v3=1 (A1, 1604.25 cm−1) states. These perturbations are observable only near level crossings involving strong Coriolis and α interactions. The energy structure within these perturbers is severely complicated by strong Coriolis and α resonances and by ? (2, 2), ? (2,−1), and ? (2,−4) interactions as already revealed by the ν2(A1, 710.16 cm−1) and ν5 (E, 701.72 cm−1) fundamentals. Interactions of the perturbing states with the ν1/ν4 dyad are particularly evident in local crossings. In total, 12 transitions belonging to the dark states and 68 perturbation-allowed transitions within the ν1/ν4 dyad have been detected among the more than 5000 transitions that have been assigned for the ν1/ν4 dyad, with Jmax and Kmax of 50 and 30, respectively. Altogether about 85% of the assigned transitions were fitted with a standard deviation of 0.221×10−3 cm−1, leading to 61 parameters of the interacting polyad. 相似文献
72.
This Note deals with two problems on stabilization of linear systems by static feedbacks which are bounded and time-delayed, namely global asymptotic stabilization and finite gain -stabilization, . Regarding the first issue, we provide, under standard necessary conditions, two types of solutions for arbitrary small bound on the control and large (constant) delay. The first solution is based on the knowledge of a static stabilizing feedback in the zero-delay case and the second solution is of nested saturation type, which extends results of Mazenc et al. [IEEE Trans. Automat. Contr. 48 (1) (2003) 57–63]. For the finite-gain -stabilization issue, we assume that the system is neutrally stable. We show the existence of a linear feedback such that, for arbitrary small bound on the control and large (constant) delay, finite gain -stability holds with respect to every -norm, . Moreover, the corresponding -gain is delay-independent. To cite this article: K. Yakoubi, Y. Chitour, C. R. Acad. Sci. Paris, Ser. I 340 2005). 相似文献
73.
The flow anisotropy of a concentrated colloidal suspension at the jamming transition is studied. It is shown that the use of rough spherical particles reduces the hydrodynamic lubrication forces between adjacent colloids and makes possible the study of the stress tensor anisotropy. At low shear rates, the suspension exerts an attractive force between two opposite surfaces, whereas at higher shear rates it becomes dilatant. Direct confocal microscopy observation of the particles organization reveal that crystallites form at high shear rate. 相似文献
74.
This work describes the preparation of polymer based monolithic materials and their use as stationary phases in capillary liquid chromatography. Multi-walled carbon nanotubes (MWCNT) were incorporated into a mixture containing benzyl methacrylate (BMA) and ethylene dimethacrylate (EDMA) as co-monomers. The optimized porogenic mixture was a ternary solution composed of cyclohexanol, 1,4-butandiol and butanol which resulted in a stable and homogeneous suspension. Six capillary columns with increasing amounts of MWCNT, from 0 to 0.4 mg mL(-1), were prepared by thermal polymerization in 0.32 mm (i.d.) and 150 mm length fused silica tubing. The chromatographic evaluation showed that the synthesized monolithic beds were mechanically stable while their porosity and permeability increased with the MWCNT content. The prepared capillary columns were tested for the separation of mixtures of ketones and phenols at an optimum flow rate of 2 μL min(-1). The results showed that incorporation of MWCNT slightly affected the retention while it enhanced the column efficiency by increasing the column efficiency by a factor of up to 9. This effect corresponded also to an improved resolution and full separation of the solutes. 相似文献