A Time-Domain Solution to the Motions of a Steered Ship in Waves

1974 ◽  
Vol 18 (01) ◽  
pp. 32-45
Author(s):  
Leonardo Pérez y Pérez
Keyword(s):  
Time Domain ◽  
Experimental Results ◽  
Damping Coefficient ◽  
Convolution Integral ◽  
Roll Damping ◽  
Ship Model ◽  
Frequency Independent ◽  
Exciting Forces

The motions of a ship in waves are expressed as linear responses to arbitrary exciting forces by means of a convolution integral. Frequency-independent nonlinearities are considered to be part of the arbitrary forces. The method is used to numerically simulate the sway, roll, and yaw motions of a ship model in waves with nonlinear roll damping coefficient and an autopilot. The agreement of the simulation with experimental results is quite reasonable. This method is restricted neither to these modes of motion nor to these nonlinearities; it can be used for all six modes of motion and any frequency-independent nonlinearity.

Advanced Fault Isolation Technique Using Electro-Optical Terahertz Pulse Reflectometry (EOTPR) for 2D and 2.5D Flip-Chip Package

2012 ◽  
Author(s):  
Lihong Cao ◽  
Manasa Venkata ◽  
Meng Yeow Tay ◽  
Wen Qiu ◽  
J. Alton ◽  
...  
Keyword(s):  
Time Domain ◽  
Flip Chip ◽  
Time Domain Reflectometry ◽  
Fault Isolation ◽  
Experimental Results ◽  
Terahertz Pulse ◽  
Isolation And Identification ◽  
Isolation Technique ◽  
Non Destructive

Abstract Electro-optical terahertz pulse reflectometry (EOTPR) was introduced last year to isolate faults in advanced IC packages. The EOTPR system provides 10μm accuracy that can be used to non-destructively localize a package-level failure. In this paper, an EOTPR system is used for non-destructive fault isolation and identification for both 2D and 2.5D with TSV structure of flip-chip packages. The experimental results demonstrate higher accuracy of the EOTPR system in determining the distance to defect compared to the traditional time-domain reflectometry (TDR) systems.

Design of a Pendulum-type Anti-rolling System for USSV and Verification Based on Roll Damping Coefficient

2019 ◽  
Vol 56 (6) ◽  
pp. 550-558
Author(s):  
Woo-Seok Jin ◽  
Yong-Ho Kim ◽  
Jun-Ho Jung ◽  
Kwangkook Lee ◽  
Dong-Hun Kim
Keyword(s):  
Damping Coefficient ◽  
Roll Damping ◽  
Rolling System

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

Comparisons of Simulation Methods for Motions of a Moored Body in Waves

1985 ◽  
Vol 107 (1) ◽  
pp. 34-41
Author(s):  
M. Takagi ◽  
K. Saito ◽  
S. Nakamura
Keyword(s):  
Wave Theory ◽  
Simulation Methods ◽  
Convolution Integral ◽  
Linear Water Wave Theory ◽  
Initial Stage ◽  
Constant Coefficients ◽  
Exciting Forces ◽  
Linear Differential ◽  
Experimental Values ◽  
The Time Domain

Based on the linear water wave theory, numerical simulations are carried out for motions in waves of a body moored by a nonlinear-type mooring system. Numerical results obtained by using the equation of motion described in the time domain with a convolution integral (C.I. method) are compared with those of the second-order linear differential equation with constant coefficients (C. C. method). These results are also compared with experimental values measured from the initial stage when the action of exciting forces starts and the validity of C.I. method is discussed.

Modal superposition in the time domain: Theory and experimental results

1995 ◽  
Vol 97 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Marinus M. Boone ◽  
Gilles Janssen ◽  
Michiel van Overbeek
Keyword(s):  
Time Domain ◽  
Experimental Results ◽  
Domain Theory ◽  
Modal Superposition ◽  
The Time Domain

scholarly journals Harmonic Cancellation

2021 ◽  
Author(s):  
Alain de Cheveigné
Keyword(s):  
Auditory System ◽  
Time Domain ◽  
Experimental Results ◽  
Target Sound ◽  
Neural Representations ◽  
Behavioral Studies ◽  
System P ◽  
Harmonic Cancellation ◽  
The Time Domain

This paper reviews the hypothesis of {\em harmonic cancellation}\ according to which an interfering sound is suppressed or canceled on the basis of its harmonicity (or periodicity in the time domain). It defines the concept, discusses theoretical arguments in its favor, and reviews experimental results that support it, or not. If correct, the hypothesis likely draws on time domain processing of temporally-accurate neural representations within the brainstem, as required also by the classic Equalization-Cancellation (EC) model of binaural unmasking. It predicts that a target sound corrupted by interference will be easier to hear if the interference is harmonic than inharmonic, all else being equal. This prediction is borne out in a number of behavioral studies, but not all. The paper reviews those results, with the aim to understand the inconsistencies and come up with a reliable conclusion for, or against, the hypothesis of harmonic cancellation within the auditory system.

Numerical Simulation on Mooring Performance of LNG-FPSO System in Realistic Seas

2005 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Md. Kamruzzaman
Keyword(s):  
Time Domain ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Time Domain Analysis ◽  
Analysis Tool ◽  
Motion Response ◽  
Non Linear ◽  
Floating System ◽  
Exciting Forces ◽  
The Time Domain

The LNG-FPSO concept is receiving much attention in recent years, due to its active usage to exploit oil and gas resources. The FPSO offloads LNG to an LNG carrier that is located close to the FPSO, and during this transfer process two large vessels are in close proximity to each other for daylong periods of time. Due to the presence of neighboring vessel, the motion response of both the vessels will be affected significantly. Hydrodynamic interactions related to wave effects may result in unfavorable responses or the risk of collisions in a multi-body floating system. Not only the motion behavior but also the second order drift forces are influenced by the neighboring structures due to interactions of the waves among the structures. A study is made on the time domain analysis to assess the behavior and the operational capability of the FPSO system moored in the sea having an LNG carrier alongside under environmental conditions such as waves, wind and currents. This paper presents an analysis tool to predict the dynamic motion response and non-linear connecting and mooring forces on a parallel-connected LNG-FPSO system due to non-linear exciting forces of wave, wind and current. Simulation for the mooring performance is also investigated. The three-dimensional source-sink technique has been applied to obtain the radiation forces and the transfer function of wave exciting forces on floating multi-bodies. The hydrodynamic interaction effect between the FPSO and the LNG carrier is included to calculate the hydrodynamic forces. For the simulation of a random sea and also for the generation of time depended wind velocity, a fully probabilistic simulation technique has been applied. Wind and current loads are estimated according to OCIMF. The effects of variations in wave, wind and current loads and direction on the slowly varying oscillations of the LNG and FPSO are also investigated in this paper. Finally, some conclusions are drawn based on the numerical results obtained from the present time domain simulations.

scholarly journals A Time Domain Passivity Control Scheme for Bilateral Teleoperation

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 325 ◽  
Author(s):  
Long Sheng ◽  
Usman Ahmad ◽  
Yongqiang Ye ◽  
Ya-Jun Pan
Keyword(s):  
Time Domain ◽  
Parametric Design ◽  
Switching Time ◽  
Experimental Results ◽  
Division Problem ◽  
Bilateral Teleoperation ◽  
Safe Operation ◽  
Guaranteed Stability ◽  
Control Scheme ◽  
And Control

Conventional time domain passivity control inevitably embodies division. Zero division can occur under a tiny force or velocity, which may be inevitable, and will be the cause of control crash. To avoid the zero division problem and control crash, we propose a switching dissipation controller for guaranteed stability. The parametric design of the proposed approach is discussed. The switching time domain passivity control is then applied to teleoperation and safe operation is achieved. Simulation and experimental results are demonstrated to validate the effectiveness of the proposed control scheme.

A Time-Domain Boundary Elements Method Applied to Multi-Body Simulations With Large Relative Displacements

2015 ◽  
Author(s):  
Rafael A. Watai ◽  
Felipe Ruggeri ◽  
Alexandre N. Simos
Keyword(s):  
Free Surface ◽  
Time Domain ◽  
Numerical Solutions ◽  
Domain Boundary ◽  
Boundary Elements ◽  
Experimental Result ◽  
Exciting Forces ◽  
Boundary Elements Method ◽  
Meshing Scheme ◽  
Multi Body

This paper presents a time domain boundary elements method that accounts for relative displacements between two bodies subjected to incoming waves. The numerical method solves the boundary value problem together with a re-meshing scheme that defines new free surface panel meshes as the bodies displace from their original positions and a higher order interpolation algorithm used to determine the wave elevation and the velocity potential distribution on new free surface collocation points. Numerical solutions of exciting forces and wave elevations are compared to data obtained in a fundamental experimental text carried out with two identical circular section cylinders, in which one was attached to a load cell and the other was forced to move horizontally with a large amplitude oscillatory motion under different velocities. The comparison of numerical and experimental result presents a good agreement.

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