Motion Analysis of TAD and TLP Platforms Operating Side by Side

2016 ◽  
Author(s):  
Mohammed Abdul Hannan ◽  
Bai Wei ◽  
Allan Ross Magee ◽  
Ankit Choudhary ◽  
Amit Jain ◽  
...  
Keyword(s):  
Stiffness Matrix ◽  
Low Frequency ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Equivalent Stiffness ◽  
Floating Bodies ◽  
Drilling Rig ◽  
Production Platform ◽  
The Time Domain

A Tender Assisted Drilling (TAD) is typically a support vessel that serves support of a drilling rig. The TAD acts as a platform for supplies and is stationed alongside the drilling rig from which the rig will work off to reduce the loads on the actual rig. While operating, the TAD needs to be structurally coupled with the floating production platform. The coupling makes sure that the Tender does not drift away from the platform and provides stiffness to the relative motions between the TAD and the production platform. Current practice is to couple the TAD and the platform by using nylon hawser ropes. The hawsers provide adequate elasticity to accommodate the low frequency motions and do not allow the TAD to drift away from the production platform. In this study the individual free floating TAD and Tension Leg Platform (TLP) system is model first using the commercial software Hydrostar. After that the technique of developing equivalent stiffness matrix to represent the TLP tendons are applied in order to simulate the influence of the tendons on TLP motions. The response of these individual models are then calculated numerically and validated against existing data. After validation is performed, coupled interactions of this two body is simulated while both the bodies are freely floating side by side. Several possible side by side orientations of the TAD and TLP are tested and the results are compared for this first phase of the study. Later, the freely floating bodies are connected to each other by means of springs. The connection between the two floating bodies is modeled using equivalent stiffness matrix for connections. The results obtained from this first phase frequency domain analysis will help to clearly understand the coupled behavior of such system under various orientations. In later phases, this model will be further developed in order to perform the time domain analysis and several innovative types of connections other than simple hawsers will be tested in order to couple this TAD and TLP system.

A Frequency Domain Analysis of Learning Control

1994 ◽  
Vol 116 (4) ◽  
pp. 781-786 ◽  
Author(s):  
C. J. Goh
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Linear Time ◽  
Planning Horizon ◽  
Time Domain Analysis ◽  
Learning Control ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Convergence Criterion ◽  
The Time Domain

The convergence of learning control is traditionally analyzed in the time domain. This is because a finite planning horizon is often assumed and the analysis in time domain can be extended to time-varying and nonlinear systems. For linear time-invariant (LTI) systems with infinite planning horizon, however, we show that simple frequency domain techniques can be used to quickly derive several interesting results not amenable to time-domain analysis, such as predicting the rate of convergence or the design of optimum learning control law. We explain a paradox arising from applying the finite time convergence criterion to the infinite time learning control problem, and propose the use of current error feedback for controlling possibly unstable systems.

Comparison of Time and Frequency Domain Analysis With Full Scale Data for the Horn Mountain Spar During Hurricane Isidore

2006 ◽  
Author(s):  
Arcandra Tahar ◽  
John Halkyard ◽  
Mehernosh Irani
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Full Scale ◽  
Frequency Domain Method ◽  
Drag Forces ◽  
The Time Domain ◽  
Scale Data

The Horn Mountain Spar is located in 1,654 m of water about 135 km from Venice, Louisiana in the Gulf of Mexico. The facility was instrumented extensively to measure key spar and riser response parameters (Edwards et. al. 2003). Halkyard et. al. (2004) and Tahar et. al. (2005) have compared measured spar responses such as motion and mooring line tensions with numerical predictions. This paper extends the work done on comparison of the full scale data during hurricane Isidore. All previous numerical simulations were based on a time domain analysis procedure. One concern related to this method is that it is computationally intensive and time consuming. In the initial stages of a project, a frequency domain solution may be an effective tool compared with a fully coupled time domain analysis. The present paper compares results of time domain and frequency domain simulations with field measurements. Particular attention has been placed on the importance of the phase relationship between motion and excitation force. In the time domain analysis, nonlinear drag forces are applied at the instantaneous position. Whereas in the frequency domain analysis, nonlinear drag forces are stochastically linearized and solutions are obtained by an iterative procedure. The time domain analysis has better agreement with the field data compared to the frequency domain. Overall, however, the frequency domain method is still promising for a quick and approximate estimation of relevant statistics. With advantages in terms of CPU time, the frequency domain method can be recommended as a tool in pre-front end engineering design or in a phase where an iterative nature of design of an offshore structure takes place.

Float-Off Operation of a Land-Built COT on Dual Transportation Barges: Time- vs. Frequency-Domain Analysis

2005 ◽  
Author(s):  
Chan K. Yang ◽  
D. H. Lee ◽  
M. H. Kim ◽  
B. N. Park ◽  
Y. T. Yang ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Domain Model ◽  
Mooring Line ◽  
Load Prediction ◽  
Floating Bodies ◽  
Realistic Situation ◽  
The Time Domain

In this paper, the float-off operation of a land-built crude oil tank (COT) loaded out and towed on launching dual-submersible barges is numerically simulated by a time-domain vessel-mooring-riser coupled dynamic analysis program with multiple floating bodies. The study is particularly focused on the maximum load prediction on connectors and the minimum gap prediction between barges and the COT. In case of simpler modeling, the time-domain simulation results are compared with frequency-domain results. Then, the time-domain model is run for more realistic situation with hawsers and mooring line. In hydrodynamic analysis, the interactions among the 3 floating bodies are fully taken into consideration. In the frequency-domain analysis, the connectors between barges are modeled by equivalent translational and rotational springs, the stiffness of which is estimated using Euler’s beam theory. In order to assess the possible occurrence of contact between COT and barges, the relative motions between barges and the COT at several points of interest were investigated.

Mechanics and Pretreatment Research of Vibration Signals for the Numerical Control Machine

2013 ◽  
Vol 676 ◽  
pp. 162-165
Author(s):  
Er Bao Peng ◽  
Hong Ge Zhang ◽  
Hong Ying Wang
Keyword(s):  
Function Analysis ◽  
Time Domain Analysis ◽  
Analysis Data ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Numerical Control ◽  
Analysis Method ◽  
Vibration Signals ◽  
The Time Domain ◽  
Control Machine

To study vibration signals processing mechanics and the analysis method of the numerical control machine. vibration signals analysis method include time and frequent domain analysis: the time domain analysis mainly has the statistical analysis and the correlation function analysis. frequency domain analysis include spectral analysis, cepstrum analysis, data envelopment analysis. vibration signals pretreatment is the most commonly used and effective method on the mechanical device condition monitor and the failure diagnosis.

Research of Gear Fault Comprehensive Diagnosis Method Based on Analysis of Vibration Signal

2014 ◽  
Vol 898 ◽  
pp. 892-895
Author(s):  
Zhan Jie Lv ◽  
Wen Xu ◽  
Gui Ji Tang ◽  
Guo Dong Han ◽  
Shu Ting Wan
Keyword(s):  
Fault Diagnosis ◽  
Vibration Signal ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Gear Fault ◽  
Gear Fault Diagnosis ◽  
The Time Domain ◽  
Envelope Spectrum ◽  
Signal Processing Methods

For gearbox common type of fault, leads to common methods gear fault diagnosis, according to the various parameters of the gearbox, to give a gearbox fault frequencies. Using mat lab signal analysis, by the time domain analysis, frequency domain analysis, cestrum analysis, signal processing methods envelope spectrum consolidated results there is a fault in the gearbox countershaft. This papers they have certain significance to gear fault diagnosis.

Initiation and development of rail corrugation based on track vibration in metro systems

2018 ◽  
Vol 232 (9) ◽  
pp. 2228-2243 ◽  
Author(s):  
Hong Xiao ◽  
Song Yang ◽  
Haoyu Wang ◽  
Si X Wu
Keyword(s):  
Dynamic Models ◽  
Three Dimensional ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Response Analysis ◽  
Characteristic Frequencies ◽  
Rail Corrugation ◽  
Metro Systems ◽  
The Time Domain

Rail corrugation, one of the most deleterious types of track wear, affects the railroad industries in many countries. Rail corrugation leads not only to vehicle and track vibration, lifespan reduction of infrastructure, and safety and passenger comfort issues but it also produces track noise. This paper, based on the track vibration theory, studies the initiation and development of rail corrugation in both the time and frequency domains. First, four track models for the frequency-domain analysis are developed to model the common short sleeper track, vibration absorbing fastener track, elastic short sleeper track and ladder sleeper track. The frequency response analysis is performed to calculate the characteristic frequencies of the track models. In order to analyse the relationship between the natural vibration of track structures and rail corrugation, the characteristic frequencies are compared with the measured passing frequencies of tracks due to rail corrugation. Second, the vehicle–track–tunnel three-dimensional dynamic models are developed for the four track structures to study the initiation of rail corrugation under the influence of track vibration using the time-domain analysis. Finally, the development of rail corrugation for the four track structures is investigated by means of the wear growth rate. Moreover, the influence of other factors, such as the curve radius, the rail–sleeper relative position, the driving velocity and the wheel–rail friction coefficient, is discussed.

scholarly journals Analysis of Three-Phase Wye-Delta Connected LLC

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3606
Author(s):  
Jing-Yuan Lin ◽  
Chuan-Ting Chen ◽  
Kuan-Hung Chen ◽  
Yi-Feng Lin
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Operation Time ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Complete Analysis ◽  
Plane Analysis ◽  
Analysis Methods ◽  
Three Phase

Three-phase wye–delta LLC topology is suitable for voltage step down and high output current, and has been used in the industry for some time, e.g., for server power and EV charger. However, no comprehensive circuit analysis has been performed for three-phase wye–delta LLC. This paper provides complete analysis methods for three-phase wye–delta LLC. The analysis methods include circuit operation, time domain analysis, frequency domain analysis, and state–plane analysis. Circuit operation helps determine the circuit composition and operation sequence. Time domain analysis helps understand the detail operation, equivalent circuit model, and circuit equation. Frequency domain analysis helps obtain the curve of the transfer function and assists in circuit design. State–plane analysis is used for optimal trajectory control (OTC). These analyses not only can calculate the voltage/current stress, but can also help design three-phase wye-delta connected LLC and provide the OTC control reference. In addition, this paper uses PSIM simulation to verify the correctness of analysis. At the end, a 5-kW three-phase wye–delta LLC prototype is realized. The specification of the prototype is a DC input voltage of 380 V and output voltage/current of 48 V/105 A. The peak efficiency is 96.57%.

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