Duffing振子倍周期分岔谱特性

应用半数值近似解析方法验证分析Duffing振子倍周期分岔规律理论结论;用增量谐波平衡法获得高精度高阶谐波半数值近似解析解。该验证过程可弥补实验方法精度提高难及数值方法需通过计算高频分辨率频谱方能有效分析的缺点。结果表明,该分析方法与Feigenbaum理论结论较吻合,证明理论结论的正确性。     

Generator of quasi-periodic oscillations featuring two-dimensional torus doubling bifurcations

A new autonomous differential dynamical system with dimension N = 4 is introduced, which has solutions in the form of stable two-frequency oscillations and features a sequence of period-doubling bifurcations of two-dimensional ergodic tori. At the points of period-doubling bifurcations, no resonances are observed on a torus and only ergodic tori exhibit doubling.     

Acoustic oscillations and elastic moduli of single gold nanorods

We present the first acoustic vibration measurements of single gold nanorods with well-characterized dimensions and crystal structure. The nanorods have an average size of 90 nm x 30 nm and display two vibration modes, the breathing mode and the extensional mode. Correlation between the dimensions obtained from electron microscope images and the vibrational frequencies of the same particle allows us to determine the elastic moduli for each individual nanorod. Contrary to previous reports on ensembles of gold nanorods, we find that the single particle elastic moduli agree well with bulk values.     

Thermally induced oscillations of helium in cryogenic apparatus

The results of an experimental study of thermally induced oscillations are presented. Relations are given for the determination of the stability limit and amplitudes of the oscillations.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 4, pp. 691–696, April, 1977.     

Pulsating submerged jet and thermally induced oscillations

Viscous fluid flow periodically ejected from a submerged open-ended tube into a large pool and sucked back into the tube is investigated. It is shown that the resulting vortices create thermally induced oscillations in the tube.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 40, No. 1, pp. 5–11, January, 1981.     

基于无网格方法的耳膜传导振动分析

耳膜的病变常常引起传导性耳聋,因此,耳膜的声音传导力学行为已引起人们的关注。耳膜为生理性非均质材料,有限元模拟计算中,需要对不同单元进行材料赋值,由于单元与单元交界处材料性能的突变而引起计算误差。本文基于无网格数值方法分析耳膜,同时将无网格数值方法计算结果和有限元计算结果及实验所得结果相比较,结果表明无网格方法在生理性非均匀介质模拟计算中是可行的,对耳膜振幅模拟是更有效的。     

On the possibility for an autooscillatory system under external periodic drive action to exhibit universal behavior characteristic of the transition to chaos via period-doubling bifurcations in conservative systems

We propose a model of an autooscillatory system that admits the physical realization of the universal Hamiltonian-type critical behavior at a threshold of the transition to chaos that is characteristic of conservative systems. For this model, an approximate discrete map is obtained and the coordinates of the corresponding critical point are evaluated.     

Influence of pressure oscillations on gas-phase content in gas-liquid flow

It has been shown experimentally that pressure oscillations in a gas-liquid flow lead to additional (in comparison with the steady case) liberation of gas phase from the dissolved state.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 1, pp. 33–35, January, 1989.     

Acoustic emission analysis of composite pressure vessels under constant and cyclic pressure

The use of acoustic emission (AE) for the detection of damage in carbon fibre composite pressure vessels was evaluated for constant and cyclic internal gas pressure loading conditions. AE was capable of monitoring the initiation and accumulation of damage events in a composite pressure vessel (CPVs), although it was not possible to reliably distinguish carbon fibre breakage from other microscopic damage events (e.g. matrix cracks, fibre/matrix interfacial cracks). AE tests performed on the carbon fibre laminate used as the skin of pressure vessels revealed that the development of damage is highly variable under constant pressure, with large differences in the rupture life and acoustic emission events at final failure. Numerical analysis of the skin laminate under constant tensile stress revealed that the high variability in the stress rupture life is due mainly to the stochastic behaviour of the carbon fibre rupture process.     

Modeling pressure relationships of inspired air into the human lung bifurcations through simulations

Applied pressure on human lung wall has great importance on setting up protective ventilatory strategies, therefore, estimating pressure relationships in terms of specific parameters would provide invaluable information specifically during mechanical ventilation (MV). A three-dimensional model from a healthy human lung MRI is analyzed by computational fluid dynamic (CFD), and results for pressure are curve fitted to estimate relationships that associate pressure to breathing time, cross section and generation numbers of intended locations. Among all possible functions, it is observed that exponential and polynomial pressure functions present most accurate results for normal breathing (NB) and MV, respectively. For validation, pressure-location curves from CFD and results from this study are compared and good correlations are found. Also, estimated pressure values are used to calculate pressure drop and airway resistance to the induced air into the lung bifurcations. It is concluded that maximum pressure drop appeared in generation number 2 and medium sized airways show higher resistance to air flow and that resistance decreased as cross sectional area increased through the model. Results from this study are in good agreement with previous studies and provide potentials for further studies on influence of air pressure on human lung tissue and reducing lung injuries during MV.     

Subharmonic. superharmonic and quasiperiodic oscillations induced by vortices

Structural oscillations of non-inner resonance and inner resonance induced by vortex shedding are studied using the method of multiple scales under different conditions. It is shown that the vortex-excited system exhibits complicated dynamic behaviours such as frequency-locked, subharmonic, superharmonic and quasiperiodic oscillations.     

基于组织切片数据的中耳鼓膜有限元分析

采用不脱钙颞骨组织切片技术获得中耳鼓膜的三维形态数据,利用HyperMesh软件通过比较不同单元类型的网格,提出了用四边形和三角形混合单元对鼓膜进行网格划分的高效高精度方法;并将分网后的模型导入ANSYS有限元分析软件。在进行了不同声强作用下的静力学特性、鼓膜的固有振动特性以及在不同频率作用下的谐响应分析后,将结果与其它文献中的计算和实验数据进行了对比,对本文所提出的基于混合单元中耳鼓膜有限元模型的可靠性进行了验证,为中耳听骨链系统的力学分析提供了理论和模型基础。     

膜的负压清洗方法研究

以中空纤维为研究对象,通过药酒澄清实验,探讨了超滤膜的清洗问题,研究了低压高流速清洗、反压清洗和负压清洗等方法对被污染膜的清洗效果,并找出了最佳清洗方法．实验结果表明,负压清洗效果优于其他方法     

Experimental study of thermally induced oscillations of gaseous helium

Results of a study of thermally induced oscillations of helium gas in semi-open and closed tubes are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 47, No. 3, pp. 453–457, September, 1984.     

Excitation of high-frequency pressure oscillations during heat exchange with diisopropylcyclohexane

Experimental data are presented on heat transfer with diisopropyl-cyclohexane accompanied by high-frequency pressure oscillations. A hypothesis is advanced relating to the mechanism causing these oscillations.     

Quantitative comparison of tympanic membrane displacements using two optical methods to recover the optical phase

The study and quantification of the tympanic membrane (TM) displacements add important information to advance the knowledge about the hearing process. A comparative statistical analysis between two commonly used demodulation methods employed to recover the optical phase in digital holographic interferometry, namely the fast Fourier transform and phase-shifting interferometry, is presented as applied to study thin tissues such as the TM. The resulting experimental TM surface displacement data are used to contrast both methods through the analysis of variance and F tests. Data are gathered when the TMs are excited with continuous sound stimuli at levels 86, 89 and 93 dB SPL for the frequencies of 800, 1300 and 2500 Hz under the same experimental conditions. The statistical analysis shows repeatability in z-direction displacements with a standard deviation of 0.086, 0.098 and 0.080 μm using the Fourier method, and 0.080, 0.104 and 0.055 μm with the phase-shifting method at a 95% confidence level for all frequencies. The precision and accuracy are evaluated by means of the coefficient of variation; the results with the Fourier method are 0.06143, 0.06125, 0.06154 and 0.06154, 0.06118, 0.06111 with phase-shifting. The relative error between both methods is 7.143, 6.250 and 30.769%. On comparing the measured displacements, the results indicate that there is no statistically significant difference between both methods for frequencies at 800 and 1300 Hz; however, errors and other statistics increase at 2500 Hz.     

Elastic oscillations induced by a moving domain wall in yttrium orthoferrite plate

Elastic oscillations induced in a 0.1-mm-thick yttrium orthoferrite plate by a moving domain wall have been observed for the first time. The results of model calculations show that these oscillations correspond to Lamb flexural waves.