Lateral Vibration of Offshore Piles Considering Pile-Water Interaction

2019 ◽  
Vol 19 (12) ◽  
pp. 1950147 ◽  
Author(s):  
Peng Fu ◽  
Kanghe Xie
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Hydrodynamic Force ◽  
Hydrodynamic Pressure ◽  
Frequency Range ◽  
Water Interaction ◽  
Dynamic Impedance ◽  
Separation Of Variable ◽  
Soil Interface ◽  
Offshore Piles

The dynamic response of an offshore pile in saturated soil subjected to lateral harmonic loading is theoretically investigated by considering the dynamic pile-water interaction. The governing equation of water is solved based on the separation of variable method, and the analytical expression of the hydrodynamic force applied on the pile is then obtained. Based on the continuous conditions at the pile-soil interface and pile-water interface, the analytical solution of the dynamic impedance of the offshore pile is derived by using transfer matrix method. To verify this solution, the dynamic impedance obtained for a cylinder in water is compared with that of a partially embedded pile. Based on this solution, the effect of hydrodynamic pressure and other parameters on the dynamic response of offshore piles is investigated. The results show that the analytical model ignoring the hydrodynamic force applied on the pile misestimates the impedance of the pile in the high frequency range.

Cobblestone Oscillations of an SES with Flexible Bag Aft Seal

1995 ◽  
Vol 39 (01) ◽  
pp. 25-41
Author(s):  
Sverre Steen ◽  
Odd M. Faltinsen
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Surface Effect ◽  
Frequency Range ◽  
Resonance Frequencies ◽  
Leakage Area ◽  
Air Cushion ◽  
Vertical Accelerations ◽  
Spatially Varying ◽  
The Mathematical Model

The high-frequency dynamic response of surface effect ships (SES) equipped with a flexible bag aft seal is studied. The results show dominating vertical accelerations in a frequency range important for passenger comfort and crew work ability. The mathematical model for the craft dynamic response accounts for the motions and accelerations in heave and pitch induced by both the unsteady uniform pressure and the spatially varying air cushion pressure. The effect of a flexible bag aft seal and a variable leakage area under the seals is included. The bag dynamic response is treated as linear and quasistatic. It is shown how the flexible bag reduces the spatial pressure resonance frequencies of a 35 m SES. The variable leakage area under the bag is found important for the response of the craft in low sea states.

SEA Subsystem Property Identification by Periodic FEM Approach

2011 ◽  
Vol 94-96 ◽  
pp. 1979-1982
Author(s):  
Jie Gao ◽  
Ke An Chen
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Periodic Structures ◽  
Low Frequency ◽  
Engineering Method ◽  
Complex Structures ◽  
High Frequency Range ◽  
Frequency Range ◽  
Remarkable Improvement ◽  
Property Identification

A study on SEA properties of periodically stiffened structure was accomplished based on the periodic theory. With application of certain software, a simulation was performed on a common periodically stiffened fuselage structure. The results indicate such modeling approach reflects relatively accurate property of subsystem in mid and high frequency range, while a remarkable improvement could also be expected in low frequency range, especially for complex structures. Such approach was approved as one reliable engineering method for solving dynamic response of periodic structures.

The Dynamic Response of Railway Track to High Frequency Lateral Excitation

1982 ◽  
Vol 24 (2) ◽  
pp. 91-95 ◽  
Author(s):  
S. L. Grassie ◽  
R. W. Gregory ◽  
K. L. Johnson
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
High Frequency ◽  
Continuous Model ◽  
Elastic Support ◽  
Railway Track ◽  
Frequency Range ◽  
Lateral Forces ◽  
Lateral Excitation ◽  
The Web

The dynamic response of railway track to lateral forces is investigated. Experimental data in the frequency range 50–1500 Hz suggest that track laid on wooden sleepers is adequately represented as a beam (the rail) on a damped elastic support (the ballast). For concrete-sleepered track the railhead appears to move significantly on the lateral flexibility of the web, and a simple continuous model is developed from which its lateral dynamic response may be found.

The Dynamic Response of Railway Track to High Frequency Vertical Excitation

1982 ◽  
Vol 24 (2) ◽  
pp. 77-90 ◽  
Author(s):  
S. L. Grassie ◽  
R. W. Gregory ◽  
D. Harrison ◽  
K. L. Johnson
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Dynamic Models ◽  
The Other ◽  
Dynamic Loads ◽  
Railway Track ◽  
Frequency Range ◽  
Vertical Excitation ◽  
Discrete Mass ◽  
Good Agreement

Two new dynamic models of railway track are presented, one continuous and the other incorporating the discrete mass of the sleepers. These models include the effect of the railpads which exist between rail and sleeper on modern track, and are used to calculate both the response of the track alone and the contact force between a moving wheel and the rail. There is good agreement between calculation and experiment in the frequency range from 50 to 1500 Hz, and it is shown that the railpad is of fundamental importance in attenuating dynamic loads in this frequency range.

Study on the Effect of Hydrodynamic Force on Deep-Water Bridges in Earthquake

2011 ◽  
Vol 255-260 ◽  
pp. 1701-1705
Author(s):  
Yue Li ◽  
Ke Hai Wang ◽  
Qian Li ◽  
Wei Han
Keyword(s):  
Dynamic Response ◽  
Water Depth ◽  
Seismic Waves ◽  
Hydrodynamic Force ◽  
Hydrodynamic Pressure ◽  
Seismic Loads ◽  
Vibration Period ◽  
Fluid Theory ◽  
Potential Fluid ◽  
Water Depths

On the basis of the potential fluid theory, the effect of hydrodynamic force on the dynamic response of a typical rectangular solid pier as prototype was analyzed at different water depths under two types of seismic waves. At the same time, the distribution of the hydrodynamic pressure, the action spot of the hydrodynamic force and the effect of fluid on the seismic response of the piers were analyzed in seismic waves. The results include the vibration period, the peak of displacement, shear and moment of pier are increased as the rise of water depth. The effect of fluid on the dynamic response of pier should not be ignored. The influence of different seismic loads on the distribution of hydrodynamic pressure is not identity.

The Dynamic Response of Railway Track to High Frequency Longitudinal Excitation

1982 ◽  
Vol 24 (2) ◽  
pp. 97-102 ◽  
Author(s):  
S. L. Grassie ◽  
R. W. Gregory ◽  
K. L. Johnson
Keyword(s):  
Experimental Data ◽  
Dynamic Response ◽  
High Frequency ◽  
Railway Track ◽  
Frequency Range ◽  
Longitudinal Excitation ◽  
Discrete Nature ◽  
Continuous Support ◽  
Good Agreement

The dynamic response of railway track to longitudinal forces is investigated. A model is presented of the rail as a uniform infinite bar resting on a continuous support. There is good agreement in the frequency range 50–1500 Hz between experimental data and the response calculated using this model. The support is significant up to a frequency of about 200 Hz, above which the rail is effectively a dashpot. The discrete nature of the support on sleepers is relatively unimportant. The track moves very much less under longitudinal forces than it does under vertical forces at these frequencies.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

HIGH FREQUENCY OHMIC LOSSES IN TERAHERTZ FREQUENCY RANGE CW KLYNOTRONS

2017 ◽  
Vol 76 (10) ◽  
pp. 929-940 ◽  
Author(s):  
Yu. S. Kovshov ◽  
S. S. Ponomarenko ◽  
S. A. Kishko ◽  
A. A. Likhachev ◽  
S. A. Vlasenko ◽  
...  
Keyword(s):  
High Frequency ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range ◽  
Ohmic Losses

scholarly journals An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

2021 ◽  
Vol 11 (4) ◽  
pp. 1932
Author(s):  
Weixuan Wang ◽  
Qinyan Xing ◽  
Qinghao Yang
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Time Integration ◽  
Low Frequency ◽  
Weak Form ◽  
High Accuracy ◽  
Numerical Dissipation ◽  
Frequency Range ◽  
Time Integration Method ◽  
Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

scholarly journals Band notched self complementaryultra wideband antenna for wireless applications

2018 ◽  
Vol 7 (2.8) ◽  
pp. 529 ◽  
Author(s):  
Ch Ramakrishna ◽  
G A.E.Satish Kumar ◽  
P Chandra Sekhar Reddy
Keyword(s):  
High Frequency ◽  
Return Loss ◽  
Wide Band ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Relative Dielectric Permittivity ◽  
Frequency Range ◽  
Ground Structure ◽  
Wireless Applications ◽  
Patch Edge

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton  substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz,  band rejected WLAN frequency range 5.6-6.5 GHz with  vswr is less than 2.

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