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991.
Loïc Chevalier Julien Bruchon Nicolas Moulin Pierre-Jacques Liotier Sylvain Drapier 《Comptes Rendus Mecanique》2018,346(8):617-633
This paper introduces a numerical method able to deal with a general bi-fluid model integrating capillary actions. The method relies first on the precise computation of the surface tension force. Considering a mathematical transformation of the surface tension virtual work, the regularity required for the solution on the evolving curved interface is weakened, and the mechanical equilibrium of the triple line can be enforced as a natural condition. Consequently, contact angles of the liquid over the solid phase result naturally from this equilibrium. Second, for an exhaustive representation of capillary actions, pressure jumps across the interface must be accounted for. A pressure enrichment strategy is used to properly compute the discontinuities in both pressure and gradient fields. The resulting method is shown to predict nicely static contact angles for some test cases, and is evaluated on complex 3D cases. 相似文献
992.
In this paper, a secure image transmission scheme based on synchronization of fractional-order discrete-time hyperchaotic systems is proposed. In this scheme, a fractional-order modified-Hénon map is considered as a transmitter, the system parameters and fractional orders are considered as secret keys. As a receiver, a step-by-step delayed observer is used, and based on this one, an exact synchronization is established. To make the transmission scheme secure, an encryption function is used to cipher the original information using a key stream obtained from the chaotic map sequences. Moreover, to further enhance the scheme security, the ciphered information is inserted by inclusion method in the chaotic map dynamics. The first contribution of this paper is to propose new results on the observability and the observability matching condition of nonlinear discrete-time fractional-order systems. To the best of our knowledge, these features have not been addressed in the literature. In the second contribution, the design of delayed discrete observer, based on fractional-order discrete-time hyperchaotic system, is proposed. The feasibility of this realization is demonstrated. Finally, different analysis are introduced to test the proposed scheme security. Simulation results are presented to highlight the performances of our method. These results show that, our scheme can resist different kinds of attacks and it exhibits good performance. 相似文献
993.
Ouerdia Megherbi Hamid Hamiche Saïd Djennoune Maamar Bettayeb 《Nonlinear dynamics》2017,90(3):1519-1533
In this paper, we discuss and investigate the impulsive synchronization of fractional-order discrete-time chaotic systems. The proposed method is based on the impulsive synchronization theory used in the integer-order case on the one hand and the mathematical analysis of the fractional-order discrete-time systems on the other hand. Sufficient conditions for the stability of synchronization error system are given, and application example with numerical simulations is illustrated in order to verify that the proposed method is applicable and effective. Furthermore, in order to validate the proposed synchronization approach, we have also provided the experimental implementation results using Arduino Mega boards. 相似文献
994.
A.?A.?BogdanEmail authorView authors OrcID profile G.?V.?Kataeva J.?G.?Khomenko A.?G.?Ilves L.?N.?Prakhova 《Applied magnetic resonance》2017,48(7):707-714
The quality of the signal received from metabolites in 1H-magnetic resonance spectroscopy (MRS) directly depends on physical parameters of the impulse sequence used, namely on Time of Echo (TE). We compare MRS (Achieva 3T PRESS 1H-MRS (TE = 53 and 144 ms, TR = 2000 ms) data acquired in supraventricular white matter and medial cortex at two various TE (53 and 144 ms) for patients with the multiple sclerosis (25 patients with the confirmed diagnosis of relapsing-remitting multiple sclerosis and 20 patients with the diagnosis of secondary progressive multiple sclerosis) and control group (21 healthy volunteers, comparable on age), to evaluate advantages and disadvantages of these two Echo Time in clinical practice. 相似文献
995.
996.
G. Guéna J. Corde S. Fouilloux J. -B. d’Espinose F. Lequeux L. Talini 《The European physical journal. E, Soft matter》2009,28(4):463-468
The present work deals with emulsions of volatile alkanes in an aqueous clay suspension, Laponite, which forms a yield stress
fluid. For a large enough yield stress (i.e. Laponite concentration), the oil droplets are prevented from creaming and the emulsions are thus mechanically stabilized.
We have studied the evaporation kinetics of the oil phase of those emulsions in contact with the atmosphere. We show that
the evaporation process is characterized by the formation of a sharp front separating the emulsion from a droplet-free Laponite
phase, and that the displacement of the front vs. time follows a diffusion law. Experimental data are confronted to a diffusion-controlled model, in the case where the limiting
step is the diffusion of the dissolved oil through the aqueous phase. The nature of the alkane, as well as its volume fraction
in the emulsion, has been varied. Quantitative agreement with the model is achieved without any adjustable parameter and we
describe the mechanism leading to the formation of a front. 相似文献
997.
R. Bernabei P. Belli F. Cappella R. Cerulli C. J. Dai A. d’Angelo H. L. He A. Incicchitti H. H. Kuang X. H. Ma F. Montecchia F. Nozzoli D. Prosperi X. D. Sheng Z. P. Ye 《The European Physical Journal C - Particles and Fields》2009,62(2):327-332
In this paper a new search for non-Paulian nuclear processes, i.e. processes normally forbidden by the Pauli Exclusion Principle
(PEP), is presented. It has been carried out at the Gran Sasso National Laboratory of the INFN by means of the highly radiopure
DAMA/LIBRA set-up (sensitive mass of about 250 kg highly radiopure NaI(Tl)). In particular, a new improved upper limit for
the spontaneous non-Paulian emission rate of protons with energy E
p
≥ 10 MeV in 23Na and 127I has been obtained: 1.63 × 10−33 s−1 (90% C.L.). The corresponding limit on the relative strength (δ
2) for the searched non-Paulian transition is δ
2≲(3–4)×10−55 (90% C.L.). Moreover, PEP-violating electron transitions in iodine atoms have also been investigated. Lifetimes shorter than
4.7×1030 s are excluded at 90% C.L.; this allows us to derive the limit δ
e
2<1.28×10−47 (90% C.L.). This latter limit can also be related to a possible finite size of the electron in composite models of quarks
and leptons providing superficial violation of the PEP; the obtained upper limit on the electron size is r
0<5.7×10−18 cm (energy scale of E≳3.5 TeV). 相似文献
998.
The spatially controlled field assisted etching method for sharpening metallic tips, in a field ion microscope (FIM), is used to study the evolution of the field emission when the tip apex radius is decreased below 1 nm. Unlike the conventional image formation in a field emission microscope (FEM), we demonstrate that at this scale the field emission is rather confined to atomic sites. A single atom apex fabricated at the end of such tips exhibits an outstanding brightness compared to other atomic tips. The measurements have been repeated for two double atom tips, with different atom-atom separations, and images of atomic field emission localization have also been obtained. We have found that the field emission intensity alternates between adjacent atoms when the applied voltage is gradually increased beyond a threshold value. 相似文献
999.
在近中性至弱碱性介质中,羧甲基纤维素钠(CMC)由于多个羧基离解而以大阴离子状态存在,它能与吖啶黄(AY)或吖啶橙(AO)阳离子借静电引力和疏水作用力而形成离子缔合复合物。此时,溶液的吸收光谱发生变化,染料在紫外和可见区的最大吸收显著降低,最大褪色波长分别位于264nm和434nm附近(AY体系)以及266nm和488nm附近(AO体系);反应有很高的灵敏度,最大摩尔吸光系数分别达7.20×107L(mol·cm)-1(AY体系λ=264nm)和1.13×108L(mol·cm)-1(AO体系λ=488nm);方法有较好的选择性,且简便快速,可用于烟丝中微量CMC的紫外可见分光光度法测定。 相似文献
1000.
In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology acco... 相似文献