Ordered bursting synchronization and complex wave propagation in a ring neuronal network

2007 ◽  
Vol 374 (2) ◽  
pp. 869-878 ◽  
Author(s):  
Qing Yun Wang ◽  
Qi Shao Lu ◽  
Guan Rong Chen
Keyword(s):  
Wave Propagation ◽  
Neuronal Network ◽  
Complex Wave ◽  
Bursting Synchronization

Modeling of Acoustic Wave Propagation HAMR Media

2005 ◽  
Author(s):  
Wei Peng ◽  
Yiao-Tee Hsia ◽  
Julius Hohlfeld
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Elastic Waves ◽  
Wave Pattern ◽  
Analytical Models ◽  
Acoustic Wave Propagation ◽  
Pump Probe ◽  
Change Measurement ◽  
Complex Wave ◽  
Acoustic Fluid

In multi-layered solids, an acoustic wave is partially reflected and partially transmitted at boundaries, which renders a too complex wave pattern to be predicted with analytical models. A Finite Element Method (FEM) based numerical model is developed to predict the acoustic wave propagation in multi-layered solids, where an ANSYS acoustic fluid element is adopted to solve this problem. The model is applied to study the pump-probe transient reflectivity measurements on Heat Assisted Magnetic Recording (HAMR) media, where the thermo-elastic waves are isolated and then subtracted from the composite reflectivity change measurement. As a result, the reflectivity change caused by the thermal decay is separated from the thermo-elastic waves, allowing a more accurate prediction and measurement of the thermal properties of HAMR media.

Wave Propagation and Instability in a Circular Semi-Infinite Liquid Jet Harmonically Forced at the Nozzle

1978 ◽  
Vol 45 (3) ◽  
pp. 469-474 ◽  
Author(s):  
D. B. Bogy
Keyword(s):  
Wave Propagation ◽  
Radiation Condition ◽  
Liquid Jet ◽  
Propagation Characteristics ◽  
Frequency Spectra ◽  
One Dimensional ◽  
Wave Numbers ◽  
Complex Wave ◽  
The Stability ◽  
The Waves

The linearized form of the inviscid, one-dimensional Cosserat jet equations derived by Green [6] are used to study wave propagation in a circular jet with surface tension. The frequency spectra are shown for complex wave numbers for a complete range of Weber numbers. The propagation characteristics of the waves are studied in order to determine which branches of the frequency spectra to use in the semi-infinite jet problem with harmonic forcing at the nozzle. Two of the four branches are eliminated by a radiation condition that energy must be outgoing at infinity; the remaining two branches are used to satisfy the nozzle boundary conditions. The variation of the jet radius along its length is shown graphically for various Weber numbers and forcing frequencies. The stability or instability is explained in terms of the behavior of the two propagating phases.

Application of Information Entropy in the Cement Grouting Test Using Impact Acoustics

2014 ◽  
Vol 584-586 ◽  
pp. 1217-1223
Author(s):  
Jin Cheng ◽  
Qing Bang Han ◽  
Hong Hui Fan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Wave Propagation ◽  
Information Entropy ◽  
Sound Field ◽  
Propagation Characteristic ◽  
Defect Size ◽  
Impact Echo ◽  
Complex Wave ◽  
Lower Entropy

The unqualified corrugated pipe grouting quality in bridges will lead to serious safety accidents. The sound field propagation in corrugated pipe structure was simulated and analyzed using finite element method, a much complex wave propagation characteristic is demonstrated, and the scattering signals caused by grouting defect are hardly distinguished. The collected impact-echo signals were processed by signal processing of information entropy technology. It is found the defect size is directly related to the information entropy. Several simulated models are constructed and measured, and the bigger size defect is, the lower entropy value is.

Analysis of Phononic Bandgap Structures With Dissipation

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Erik Andreassen ◽  
Jakob S. Jensen
Keyword(s):  
Wave Propagation ◽  
Propagation Constant ◽  
Low Frequency ◽  
Homogenization Theory ◽  
Complex Frequency ◽  
Frequency Wave ◽  
Complex Wave ◽  
Viscoelastic Composites ◽  
Periodic Materials ◽  
Loss Factors

We study wave propagation in periodic materials with dissipation using two different formulations. An ω(k)-formulation yields complex frequency solutions for nonvanishing dissipation whereas a k(ω)-formulation leads to complex wave numbers. For small (realistic) levels of material dissipation and longer wavelengths, we show that the two formulations produce nearly identical results in terms of propagation constant and wave decay. We use the k(ω)-formulation to compute loss factors with dissipative bandgap materials for steady-state wave propagation and create simplified diagrams that unify the spatial loss factor from dissipative and bandgap effects. Additionally, we demonstrate the applicability of the k(ω)-formulation for the computation of the band diagram for viscoelastic composites and compare the computed loss factors for low frequency wave propagation to existing results based on quasi-static homogenization theory.

Finite Element Simulation of Axisymmetric Elastic and Electroelastic Wave Propagation Using Local-Domain Wave Packet Enrichment

2021 ◽  
Vol 144 (2) ◽  
Author(s):  
Amit Kumar ◽  
Santosh Kapuria
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Wave Packet ◽  
Equations Of Motion ◽  
Time Integration ◽  
Coupled System ◽  
Integration Scheme ◽  
Local Domain ◽  
Complex Wave ◽  
Wave Modes

Abstract A local-domain wave packet enriched multiphysics finite element (FE) formulation is employed for accurately solving axisymmetric wave propagation problems in elastic and piezoelastic media, involving complex wave modes and sharp jumps at the wavefronts, which pose challenges to the conventional FE solutions. The conventional Lagrangian interpolations for the displacement and electric potential fields are enriched with the element-domain sinusoidal functions that satisfy the partition of unity condition. The extended Hamilton’s principle is employed to derive the coupled system of equations of motion which is solved using the simple Newmark-β direct time integration scheme without resorting to any remeshing near the wavefronts or post-processing. The performance of the enrichment is assessed for the axisymmetric problems of impact waves in elastic and piezoelectric cylinders and elastic half-space, bulk and Rayleigh waves in the semi-infinite elastic domain and ultrasonic Lamb wave actuation and propagation in plate-piezoelectric transducer system. The element shows significant improvement in the computational efficiency and accuracy over the conventional FE for all problems, including those involving multiple complex wave modes and sharp discontinuities in the fields at the wavefronts.

Observing Complex Wave Propagation

Science ◽  
2000 ◽  
Vol 288 (5469) ◽  
pp. 1133k-1133
Keyword(s):  
Wave Propagation ◽  
Complex Wave

Finite‐difference modeling of sonic wavefields with a dipping interface

Geophysics ◽  
1997 ◽  
Vol 62 (4) ◽  
pp. 1270-1277
Author(s):  
Hsui‐lin Liu ◽  
Michael Prange ◽  
Francois Daube
Keyword(s):  
Wave Propagation ◽  
Reflection Coefficient ◽  
Finite Difference ◽  
Amplitude Variation ◽  
Sh Waves ◽  
Complex Wave ◽  
Hard Formation ◽  
Sonic Logs ◽  
Horizontal Interface ◽  
Velocity Bias

Formation bedding can cause complex wave propagation in a borehole and introduce velocity bias in sonic logs. Because of the lack of symmetry, little is known about sonic wavefields propagating through a dipping bed. In this paper, we investigate effects on the sonic dipole and monopole wavefields across a dipping interface using a 3-D finite‐difference method. For dipole wavefields propagating from a soft to a hard formation across a dipping interface, the transmission is reduced greatly when compared with a horizontal interface. The different transmissions of SV‐ and SH‐waves through the dipping interface result in significant azimuthal amplitude variation and generate large cross‐coupled components. This apparent anisotropy should be taken into account when estimating formation shear anisotropy in a dipping formation. For monopole wavefields, the azimuthal averaging caused by a dipping interface reduces the reflection across an interface. This may affect fracture evaluation using the Stoneley reflection coefficient in a dipping formation.

Sign in / Sign up

Export Citation Format

Share Document