Transient response of an open resonator in the time domain

1997 ◽  
Vol 18 (2) ◽  
pp. 405-429 ◽  
Author(s):  
A. A. Vertiy ◽  
S. P. Gavrilov ◽  
D. S. Armağan ◽  
I. Ölçer
Keyword(s):  
Transient Response ◽  
Time Domain ◽  
Open Resonator ◽  
The Time Domain

Generalized Modes in Time-Domain Seakeeping Calculations

2012 ◽  
Vol 56 (04) ◽  
pp. 215-233
Author(s):  
Johan T. Tuitman ◽  
Šime Malenica ◽  
Riaan van't Veer
Keyword(s):  
Rigid Body ◽  
Transient Response ◽  
Time Domain ◽  
Large Amplitude ◽  
Degrees Of Freedom ◽  
Mode Shapes ◽  
Nonlinear Load ◽  
Large Amplitude Motions ◽  
Rigid Body Modes ◽  
The Time Domain

The concept of "generalized modes" is to describe all degrees of freedom by mode shapes and not using any predefined shape, like rigid body modes. Generalized modes in seakeeping computations allow one to calculate the response of a single ship, springing, whipping, multibody interaction, etc., using a uniform approach. The generalized modes have already been used for frequency-domain seakeeping calculations by various authors. This article extents the generalized modes methodology to be used for time-domain seakeeping computations, which accounts for large-amplitude motions of the rigid-body modes. The time domain can be desirable for seakeeping computations because it is easy to include nonlinear load components and to compute transient response, like slamming and whipping. Results of multibody interaction, two barges connected by a hinge, whipping response of a ferry resulting from slamming loads, and the response of a flexible barge are presented to illustrate the theory.

Time- and Frequency- Domain Analysis of Transient Electroosmotic Flow Induced by Sinusoidal AC Electric Field in a Curved Microtube

2005 ◽  
Author(s):  
Win-Jet Luo ◽  
Jia-Kun Chen ◽  
Ruey-Jen Yang
Keyword(s):  
Phase Shift ◽  
Electric Field ◽  
Transient Response ◽  
Time Domain ◽  
Electroosmotic Flow ◽  
Sustained Oscillation ◽  
Sustained Oscillations ◽  
Ac Electric Field ◽  
Velocity Response ◽  
The Time Domain

A backwards-Euler time-stepping numerical method is applied to simulate the transient response of electroosmotic flow in a curved microtube. The velocity responses of the flow fields induced by applied sinusoidal AC electric fields of different frequencies are investigated. The transient response of the system is fundamentally important since both the amplitude and the time duration of the transient response must be maintained within tolerable or prescribed limits. When a sinusoidal AC electric field is applied, the transient response of the output velocity oscillates in the time-domain. However, after a certain settling time, the output velocity attains a sustained oscillation with the same amplitude as the driving field. In this study, the transient response of the electroosmotic flow is characterized by the time taken by the velocity response to reach the first peak, the peak of the sustained oscillation, the maximum overshoot, the settling time, and the bandwidth of the sustained oscillations in the time-domain. Meanwhile, the performance of the system is identified by plotting the output velocity response and the output velocity phase-shift against the frequency of the applied signal. A finite time is required for the momentum to diffuse fully from the walls to the center of the curved microtube cross-section. As the applied frequency is increased, the maximum overshoot and the bandwidth and peak of the sustained oscillations gradually decrease since insufficient time exists for the momentum to diffuse fully to the center of the microtube. Additionally, the phase-shift between the applied electric field and the output velocity response gradually increases as the frequency of the applied signal is increased.

scholarly journals Transient Response Estimation of an Offshore Wind Turbine Support System

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 891 ◽  
Author(s):  
Fushun Liu ◽  
Xingguo Li ◽  
Zhe Tian ◽  
Jianhua Zhang ◽  
Bin Wang
Keyword(s):  
Wind Turbine ◽  
Frequency Domain ◽  
Transient Response ◽  
Time Domain ◽  
Initial Conditions ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Domain Method ◽  
The Time Domain ◽  
External Loads

To obtain reliable estimations of the dynamic responses of high-rising marine structures such as offshore wind turbines with obvious nonzero initial conditions, traditional frequency-domain methods cannot be employed because they provide only steady-state results. A novel frequency-domain transient response estimation method for offshore wind turbines is presented in this paper. This method builds upon a recent, significant theoretical development, which found that expressions of external loads in the frequency domain can be obtained by discretizing their eigenvalues and corresponding complex coefficients rather than directly by discrete Fourier transform (DFT) analysis, which makes it possible to deal with nonzero conditions in the frequency domain. One engineering advantage of this approach is its computational efficiency, as the motion equations of the system can be solved in the frequency domain. In order to demonstrate this approach, a case of a monopile-supported wind turbine with nonzero initial conditions was investigated. The numerical results indicate that the approach matches well with the time-domain method, except for a small, earlier portion of the estimated responses. A second case study of a sophisticated, jacket support wind turbine, involving practical issues such as complex external loads and computation efficiency, is also discussed, and comparisons of the results with the time-domain method and traditional frequency-domain method using the commercial software ANSYS are included here.

Transient Response of Irregular Surface by Periodically Distributed Semi-Sine Shaped Valleys: Incident SH Waves

2019 ◽  
Vol 14 (01) ◽  
pp. 2050005 ◽  
Author(s):  
Mehdi Panji ◽  
Saeed Mojtabazadeh-Hasanlouei
Keyword(s):  
Transient Response ◽  
Time Domain ◽  
Seismic Waves ◽  
Domain Boundary ◽  
Irregular Surface ◽  
Engineering Structures ◽  
Sh Waves ◽  
Corrugated Surfaces ◽  
Incident Plane ◽  
The Time Domain

An advanced direct half-plane time-domain boundary element method (BEM) was applied to obtain the seismic response of a linear elastic irregular surface including periodically distributed semi-sine shaped valleys subjected to propagating obliquely incident plane SH waves. After developing the method for complex multiple surface topographies, some verification examples were solved and compared with those of the published works. Then, the transient response of a rough surface with 2–16 semi-sine shaped valleys was determined as synthetic seismograms. In this regard, the depth ratio of the valleys was sensitized. Finally, amplification patterns of the surface were presented in some cases. The results showed that the method was able to analyze the multipart models in the time-domain. Moreover, the response of the sinusoidal corrugated surfaces was very effective against seismic waves in forming different patterns. The method was recommended to researchers for transient analysis of complex engineering structures and composite materials in nanoscale.

ELECTROMAGNETIC TRANSIENT RESPONSE OF A CONDUCTING SPHERE EMBEDDED IN A CONDUCTIVE MEDIUM

Geophysics ◽  
1973 ◽  
Vol 38 (5) ◽  
pp. 864-893 ◽  
Author(s):  
Shri Krishna Singh
Keyword(s):  
Transient Response ◽  
Time Domain ◽  
Massive Sulfide ◽  
Displacement Current ◽  
Static Approximation ◽  
Electromagnetic Transient ◽  
Conducting Sphere ◽  
Quasi Static Approximation ◽  
Displacement Currents ◽  
The Time Domain

This paper is concerned with the time‐domain electromagnetic prospecting of massive sulfide ore bodies which are surrounded by conductive host rocks. The electromagnetic transient response of a permeable and conducting sphere embedded in a finitely conducting infinite space is derived. The source is a magnetic dipole of arbitrary orientation which is located outside the sphere. The contributions from the displacement currents have been neglected. The solution thus obtained is compared with the known solution under “quasi‐static” approximation in which the displacement current in the sphere and both the conduction and the displacement currents in the outer medium are neglected. From the numerical results presented, it is clear that the validity of the quasi‐static approximation in the time domain, if the outer host rock is conductive, must be carefully investigated. If the finite outer conductivity is taken into account, magnetic modes are modified and electric modes become important. Five response functions, each a function of five parameters, are required to describe the secondary magnetic field.

On the Electromagnetic Pulse Response of a Dipole Over a Plane Surface

1974 ◽  
Vol 52 (2) ◽  
pp. 193-196 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Transient Response ◽  
Time Domain ◽  
Electromagnetic Pulse ◽  
Plane Surface ◽  
Low Frequency ◽  
Pulse Response ◽  
Frequency Region ◽  
Earth Model ◽  
Vertical Electric Dipole ◽  
The Time Domain

Using a surface impedance description, the electromagnetic fields of a vertical electric dipole are considered for a plane earth model. Particular attention is paid to the low-frequency region where the range to the observer may not be electrically large. The consequences in the time domain are also considered. Here, it is shown that the tail of the transient response is sensitive to the traditional low-frequency approximations that are usually accepted without question.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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