scholarly journals A Fully Nonlinear, Dynamically Consistent Numerical Model for Ship Maneuvering in a Seaway

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Ray-Qing Lin ◽  
Weijia Kuang
Keyword(s):  
Experimental Data ◽  
Time Series ◽  
Adaptive Algorithm ◽  
Ship Motion ◽  
Frequency Variation ◽  
Physical Domain ◽  
Motion Model ◽  
Ship Maneuvering ◽  
Fully Nonlinear ◽  
Ship Tracks

This is the continuation of our research on development of a fully nonlinear, dynamically consistent, numerical ship motion model (DiSSEL). In this paper we report our results on modeling ship maneuvering in arbitrary seaway that is one of the most challenging and important problems in seakeeping. In our modeling, we developed an adaptive algorithm to maintain dynamical balances numerically as the encounter frequencies (the wave frequencies as measured on the ship) varying with the ship maneuvering state. The key of this new algorithm is to evaluate the encounter frequency variation differently in the physical domain and in the frequency domain, thus effectively eliminating possible numerical dynamical imbalances. We have tested this algorithm with several well-documented maneuvering experiments, and our results agree very well with experimental data. In particular, the numerical time series of roll and pitch motions and the numerical ship tracks (i.e., surge, sway, and yaw) are nearly identical to those of experiments.

scholarly journals Prediction of Ship Unsteady Maneuvering in Calm Water by a Fully Nonlinear Ship Motion Model

2012 ◽  
Vol 2012 ◽  
pp. 1-11
Author(s):  
Ray-Qing Lin ◽  
Tim Smith ◽  
Michael Hughes
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Ship Motion ◽  
Ship Motions ◽  
Motion Model ◽  
Forward Speed ◽  
Fully Nonlinear ◽  
Six Degrees Of Freedom ◽  
Calm Water

This is the continuation of our research on development of a fully nonlinear, dynamically consistent, numerical ship motion model (DiSSEL). In this study we will report our results in predicting ship motions in unsteady maneuvering in calm water. During the unsteady maneuvering, both the rudder angle, and ship forward speed vary with time. Therefore, not only surge, sway, and yaw motions occur, but roll, pitch and heave motions will also occur even in calm water as heel, trim, and sinkage, respectively. When the rudder angles and ship forward speed vary rapidly with time, the six degrees-of-freedom ship motions and their interactions become strong. To accurately predict the six degrees-of-freedom ship motions in unsteady maneuvering, a universal method for arbitrary ship hull requires physics-based fully-nonlinear models for ship motion and for rudder forces and moments. The numerical simulations will be benchmarked by experimental data of the Pre-Contract DDG51 design and an Experimental Hull Form. The benchmarking shows a good agreement between numerical simulations by the enhancement DiSSEL and experimental data. No empirical parameterization is used, except for the influence of the propeller slipstream on the rudder, which is included using a flow acceleration factor.

Analysis of Experimental Data From Ship Trajectories of Turning Circles in a Regular Seaway

2010 ◽  
Author(s):  
Joseph T. Klamo ◽  
Ray-Qing Lin
Keyword(s):  
Experimental Data ◽  
Quantitative Analysis ◽  
Time Varying ◽  
Ship Maneuvering ◽  
New Findings ◽  
Self Consistent ◽  
Calm Water ◽  
Experimental Laboratory ◽  
Ship Tracks ◽  
Good Agreement

The accurate prediction of the track of a ship maneuvering in a seaway is one of the most important tasks in seakeeping. Most ship maneuvering studies, both experimental and numerical, focus on maneuvering in calm water. Recently, Lin and Klamo (2010) used the Digital Self-consistent Ship Experimental Laboratory (DiSSEL) to study the ship track of a turning circle maneuver in a wave field. In that study, it was shown that their simulated ship trajectories had good agreement with experimentally measured tracks. This agreement motivated the following quantitative analysis of the experimental data to characterize the effects that wave impacts have on turning circle ship tracks. Our method involves describing the ship trajectories as sinusoids with time-varying means. We also estimate the uncertainty in the results from our analysis of the experimental measurements. The quantitative analysis shows overall agreement with Lin and Klamo (2010). New findings are also discussed such as changes in the distance and time to complete the maneuver as well as the speed and preferred directions of a drifting turning circle.

Prediction of ship steering capabilities with a fully nonlinear ship motion model. Part 1: Maneuvering in calm water

2010 ◽  
Vol 15 (2) ◽  
pp. 131-142 ◽  
Author(s):  
Ray-Qing Lin ◽  
Michael Hughes ◽  
Tim Smith
Keyword(s):  
Ship Motion ◽  
Motion Model ◽  
Fully Nonlinear ◽  
Ship Steering ◽  
Calm Water ◽  
Nonlinear Ship Motion

Correlation in the heart rate data

1998 ◽  
Vol 2 ◽  
pp. 141-148
Author(s):  
J. Ulbikas ◽  
A. Čenys ◽  
D. Žemaitytė ◽  
G. Varoneckas
Keyword(s):  
Nonlinear Dynamics ◽  
Experimental Data ◽  
Heart Rate ◽  
Time Series ◽  
Cardiovascular Function ◽  
Statistical Properties ◽  
Rate Data ◽  
Heart Rate Data ◽  
Dynamical Nature ◽  
Analysis Of Time Series

Variety of methods of nonlinear dynamics have been used for possibility of an analysis of time series in experimental physiology. Dynamical nature of experimental data was checked using specific methods. Statistical properties of the heart rate have been investigated. Correlation between of cardiovascular function and statistical properties of both, heart rate and stroke volume, have been analyzed. Possibility to use a data from correlations in heart rate for monitoring of cardiovascular function was discussed.

scholarly journals Time Series Analysis of Non-stationary Ship Motion Data

2005 ◽  
Vol 112 (0) ◽  
pp. 301-306
Author(s):  
Toshio ISEKI
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Ship Motion ◽  
Motion Data ◽  
Series Analysis

Stabilization of the Ship Motion by Restricted Control

2020 ◽  
Vol 28 (4) ◽  
pp. 106-123
Author(s):  
G.M. Dovgobrod ◽  
Keyword(s):  
Feedback Linearization ◽  
Control Algorithm ◽  
Linearization Method ◽  
Ship Motion ◽  
Control Law ◽  
Motion Model ◽  
Lateral Deviation ◽  
Bounded Curvature ◽  
Trajectory Attractor ◽  
Singularity Point

. The article presents an algorithm for controlling the motion of an insufficiently controlled ship along a trajectory with a continuous bounded curvature, based on the feedback linearization method. The algorithm allows restricting the control signal, while the state vector of the ship motion model does not approach the singularity point of the control law. The control algorithm returns the ship to the specified trajectory-attractor at any lateral deviation of the ship from the specified trajectory.

Clustering Applied to Large Sets of Environmental Conditions for Selecting Typical Scenarios for Ship Maneuvering Real-Time Simulations

2021 ◽  
Author(s):  
Felipe M. Moreno ◽  
Eduardo A. Tannuri
Keyword(s):  
Time Series ◽  
Cluster Analysis ◽  
Environmental Conditions ◽  
Wind Waves ◽  
Fast Time ◽  
Large Set ◽  
Ship Maneuvering ◽  
Partitioning Around Medoids ◽  
Waves And Currents ◽  
Maneuvering Simulations

Abstract The methodology described in this paper is used to reduce a large set of combined wind, waves, and currents to a smaller set that still represents well enough the desired site for ship maneuvering simulations. This is achieved by running fast-time simulations for the entire set of environmental conditions and recording the vessel’s drifting time-series while it is controlled by an automatic-pilot based on a line-of-sight algorithm. The cases are then grouped considering how similar the vessel’s drifting time-series are, and one environmental condition is selected to represent each group found by the cluster analysis. The measurement of dissimilarity between the time-series is made by application of Dynamic Time Warping and the Cluster Analysis is made by the combination of Partitioning Around Medoids algorithm and the Silhouette Method. Validation is made by maneuvering simulations made with a Second Deck Officer.

Software Tool for Assessment of Complexity and Variability in Physiological Signals of Respiration

2011 ◽  
Vol 1 (2) ◽  
pp. 28-53
Author(s):  
Ireneusz Jablonski ◽  
Kamil Subzda ◽  
Janusz Mroczka
Keyword(s):  
Complex System ◽  
Experimental Data ◽  
Time Series ◽  
Data Analysis ◽  
Input Signal ◽  
Software Tool ◽  
Point Of View ◽  
Software Implementation ◽  
Physiological Signals ◽  
Event Time

In this paper, the authors examine software implementation and the initial preprocessing of data and tools during the assessment of the complexity and variability of long physiological time-series. The algorithms presented advance a bigger Matlab library devoted to complex system and data analysis. Commercial software is unavailable for many of these functions and is generally unsuitable for use with multi-gigabyte datasets. Reliable inter-event time extraction from input signal is an important step for the presented considerations. Knowing the distribution of the inter-event time distances, it is possible to calculate exponents due to power-law scaling. From a methodology point of view, simulations and considerations with experimental data supported each stage of the work presented. In this paper, initial calibration of the procedures with accessible data confirmed assessments made during earlier studies, which raise objectivity of measurements planned in the future.

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