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801.
802.
《Communications in Nonlinear Science & Numerical Simulation》2014,19(12):4196-4212
This study presents a direct comparison of measured and predicted nonlinear vibrations of a clamped–clamped steel beam with non-ideal boundary conditions. A multi-harmonic comparison of simulations with measurements is performed in the vicinity of the primary resonance. First of all, a nonlinear analytical model of the beam is developed taking into account non-ideal boundary conditions. Three simulation methods are implemented to investigate the nonlinear behavior of the clamped–clamped beam. The method of multiple scales is used to compute an analytical expression of the frequency response which enables an easy updating of the model. Then, two numerical methods, the Harmonic Balance Method and a time-integration method with shooting algorithm, are employed and compared one with each other. The Harmonic Balance Method enables to simulate the vibrational stationary response of a nonlinear system projected on several harmonics. This study then proposes a method to compare numerical simulations with measurements of all these harmonics. A signal analysis tool is developed to extract the system harmonics’ frequency responses from the temporal signal of a swept sine experiment. An evolutionary updating algorithm (Covariance Matrix Adaptation Evolution Strategy), coupled with highly selective filters is used to identify both fundamental frequency and harmonic amplitudes in the temporal signal, at every moment. This tool enables to extract the harmonic amplitudes of the output signal as well as the input signal. The input of the Harmonic Balance Method can then be either an ideal mono-harmonic signal or a multi-harmonic experimental signal. Finally, the present work focuses on the comparison of experimental and simulated results. From experimental output harmonics and numerical simulations, it is shown that it is possible to distinguish the nonlinearities of the clamped–clamped beam and the effect of the non-ideal input signal. 相似文献
803.
Christian Rodenbücher Andrea Jauß Viktor Havel Rainer Waser Kristof Szot 《固体物理学:研究快报》2014,8(9):781-784
Confocal Raman microscopy was applied in order to investigate the homogeneity of donor doping in Nb:SrTiO3 single crystals. Measurements of local Raman spectra revealed a systematic relation between the intensity of the Raman signal and the donor content of the crystals. We successfully elaborated a correspondence between the electronic structure and the intensity of the Raman lines using a crystal with macroscopic inhomogeneity as a demonstration sample. By mapping the distribution of the intensity of the Raman signal, we identified a characteristic inhomogeneous structure related to the presence of clusters with sizes of 5 µm to 20 µm, indicating inhomogeneous donor distribution caused by flaws introduced during crystal growth. Hence, we propose confocal Raman microscopy as a convenient technique for investigating the homogeneity and quality of doped perovskite surfaces, which are needed for various technological applications. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
804.
The accurate computation of anharmonic vibrational states for medium to large molecules is a requirement for the detailed understanding of nonlinear multidimensional infrared spectra and the dynamical information encoded in them. The vibrational configuration interaction (VCI) method constitutes a particularly promising tool in this respect. It is generally hampered though by its unfavorable scaling with respect to system size. We analyze the scaling behavior of several well‐known as well as some new approximate VCI schemes in detail, which are complementary to the class of configuration selection schemes developed recently. We find that the combination of a configuration space partitioning, possibly based on configuration selection, with energetic thresholding and resonance screening provides an efficient scheme for the reduction of computational effort involved in VCI calculations while at the same time maintaining sufficient accuracy for the vibrational energies. © 2012 Wiley Periodicals, Inc. 相似文献
805.
O. Cadot A. Boudaoud C. Touzé 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(3):399-407
A vibrating plate is set into a chaotic state of wave turbulence by either a periodic or a random local forcing. Correlations
between the forcing and the local velocity response of the plate at the forcing point are studied. Statistical models with
fairly good agreement with the experiments are proposed for each forcing. Both distributions of injected power have a logarithmic
cusp for zero power, while the tails are Gaussian for the periodic driving and exponential for the random one. The distributions
of injected work over long time intervals are investigated in the framework of the fluctuation theorem, also known as the
Gallavotti-Cohen theorem. It appears that the conclusions of the theorem are verified only for the periodic, deterministic
forcing. Using independent estimates of the phase space contraction, this result is discussed in the light of available theoretical
framework. 相似文献
806.
We propose a new measure of vulnerability of a node in a complex network. The measure is based on the analogy in which the nodes of the network are represented by balls and the links are identified with springs. We define the measure as the node displacement, or the amplitude of vibration of each node, under fluctuation due to the thermal bath in which the network is supposed to be submerged. We prove exact relations among the thus defined node displacement, the information centrality and the Kirchhoff index. The relation between the first two suggests that the node displacement has a better resolution of the vulnerability than the information centrality, because the latter is the sum of the local node displacement and the node displacement averaged over the entire network. 相似文献
807.
Gorakh Nath 《Chinese Journal of Physics (Taipei)》2018,56(6):2741-2752
Similarity solutions for a spherical shock wave in a mixture of small solid particles of micro size and a non-ideal gas are discussed under the influence of the gravitational field with monochromatic radiation. The solid particles are uniformly distributed in the mixture, and the shock wave is assumed to be driven by a piston. It is assumed that the equilibrium flow-conditions are maintained and the moving piston continuously supplies the variable energy input. Due to the central mass () at the origin (Roche model), the medium is considered to be under the influence of the gravitational field. In comparison to the attraction of the central mass at the origin, the gravitational effect of the mixture itself is neglected. The density of the undisturbed medium is assumed to be constant in order to obtain the self-similar solutions. The effect of the parameter of non-idealness of the gas , the mass concentration of solid particles in the mixture μp, the ratio of the density of solid particles to the initial density of the gas Ga and the gravitational parameter G0 are obtained. It is shown that due to an increase in the gravitational parameter the compressibility of the medium at any point in the flow field behind the shock front decrease and the flow variables velocity, pressure, radiation flux and shock strength are increased. Also, an increase in the ratio of the density of solid particles to the initial density of the gas Ga and the gravitational parameter G0 has the same effect on the shock strength and the reverse effect on the compressibility. The non-idealness of the gas causes a decrease in the shock strength and widens the disturbed region between the piston and the shock. 相似文献
808.
《Mendeleev Communications》2023,33(3):353-356
It is shown that the electronic virial-based correlation should be used to estimate bonding contributions to the rigidity of molecular vibrations in crystals. 相似文献