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991.
992.
K. R. Jayaprakash Yuli Starosvetsky Alexander F. Vakakis Maxime Peeters Gaetan Kerschen 《Nonlinear dynamics》2011,63(3):359-385
We study standing waves (nonlinear normal modes—NNMs) and band zones in finite granular chains composed of spherical granular
beads in Hertzian contact, with fixed boundary conditions. Although these are homogeneous dynamical systems in the notation
of Rosenberg (Adv. Appl. Mech. 9:155–242, 1966), we show that the discontinuous nature of the dynamics leads to interesting effects such as separation between beads, NNMs
that appear as traveling waves (these are characterized as pseudo-waves), and localization phenomena. In the limit of infinite
extent, we study band zones, i.e., pass and stop bands in the frequency–energy plane of these dynamical systems, and classify
the essentially nonlinear responses that occur in these bands. Moreover, we show how the topologies of these bands significantly
affect the forced dynamics of these granular media subject to narrowband excitations. This work provides a classification
of the coherent (regular) intrinsic dynamics of one-dimensional homogeneous granular chains with no pre-compression, and provides
a rigorous theoretical foundation for further systematic study of the dynamics of granular systems, e.g., the effects of disorders
or clearances, discrete breathers, nonlinear localized modes, and high-frequency scattering by local disorders. Moreover,
it contributes toward the design of granular media as shock protectors, and in the passive mitigation of transmission of unwanted
disturbances. 相似文献
993.
994.
Alexander Horn Dirk Wortmann Andreas Brand Ilya Mingareev 《Applied Physics A: Materials Science & Processing》2010,101(2):231-235
A modified Mach–Zehnder interferometer set-up combined with microscope objectives has been developed for the measurement of
phase changes in the processed material sample, like modification and melting of glass. The white light is generated by focusing
ultrafast laser radiation (t
p=80 fs) in a sapphire crystal using a micro-lens array to minimize temporal and spatial fluctuations in the white-light continuum.
Lateral and coaxial pump-probe measurements of the phase changes during material processing are performed using two coupled
ultrafast laser sources at different repetition rates (f
rep=1 Hz–1 MHz). The optical phase shift and therefore the refractive index of the material are calculated from the interference
images using two approaches. The knowledge of the refractive index during the laser processing with a temporal resolution
in the ps-range and a spatial resolution of several microns leads to a better understanding of the initial processes for the
permanent material modifications. 相似文献
995.
氟胺氰菊酯的定性定量分析 总被引:4,自引:0,他引:4
氟胺氰菊酯是一种用于蜜峰的高效杀螨剂。从20%商品氟胺氰菊酯粉剂中通过硅胶柱层板分离得到了96.6%的纯品并用FTIR和GC/MC进行定性量测定。采用GC/MS定量分析的方法,氟胺氰菊酯的浓度在0.05-10mg/L范围为线性响应,最低检测极限为 0.01mg/L。采用R(-)N-3,5-二硝基苯甲酰-苯基甘氨酸和长链烃的硅胶微粒手性柱,可成功地分离氟胺氰菊酯的二种旋光异构体,它们在商品氟胺氰菊酯中的比例近似为1:1。 相似文献
996.
Alexander M. Krasnosel'skii Reinhard MennickenDmitrii I. Rachinskii 《Journal of Differential Equations》2002,179(1):97-132
The paper is concerned with Hopf bifurcations in systems of autonomous ordinary differential equations with a parameter. The principal distinction between usual theorems on Hopf bifurcations and our results is that here the linearized equation is degenerate and independent of the parameter. We present sufficient conditions for a parameter value to be a bifurcation point and analyze properties of small cycles arising in the vicinity of the equilibrium. Sublinear nonlinearities play the main role in the results obtained. 相似文献
997.
998.
999.
Each nonzero solution of the stationary Schrödinger equation u(x)–c(r)u(x)=0 in R
n
with a nonnegative radial potential c(r) must have certain minimal growth at infinity. If r
2
c(r)=O(1), r, then a solution having power growth at infinity, is a generalized harmonic polynomial. 相似文献
1000.
Alexander Blokh Adam Fieldsteel 《Proceedings of the American Mathematical Society》2002,130(12):3571-3578
We characterize those subsets of the positive integers with the property that, whenever a point in a dynamical system enters a compact set along , contains a recurrent point. We do the same for uniform recurrence.