Probability of Ship High-Runs from Phase-Space Data

2020 ◽  
Vol 64 (01) ◽  
pp. 81-97
Author(s):  
Ioannis Kontolefas ◽  
Kostas J. Spyrou
Keyword(s):  
Phase Space ◽  
High Speed ◽  
Abnormal Behavior ◽  
Motion Patterns ◽  
Following Seas ◽  
Wave Celerity ◽  
Speed Level ◽  
Surf Riding ◽  
Space Data ◽  
Nonlinear Ship Motion

A clustering scheme has been applied for capturing qualitatively different surge motion patterns in the phase space. The scheme enables the identification of "high-run" incidents as soon as such motions are triggered and while their phenomenology has not yet been well developed. A "high run" is a surf-riding-like behavior, appearing in irregular following seas. The concept of finite-time coherent sets is exploited for deriving estimates of the probability of high-runs. The method is verified by identifying independently the corresponding hyperbolic Lagrangian coherent structures; then, consistency is sought between the two approaches. An important feature of the method is that it does not rely on the use of some empirical criterion for the high-run threshold, such as one based on the exceedance of an arbitrary high-speed level. Despite its computational burden, the proposed scheme offers "objective" statistical information on a ship's high-run tendency that can be used for benchmarking simpler (approximative) probability calculation schemes. 1. Introduction Current efforts to assess a ship's tendency for abnormal behavior in extreme seas are still limited from our inadequate grasp of the full variety of nonlinear ship motion phenomena that could be realized in an irregular seaway. A classification of these motion patterns would provide a sound basis for developing probabilistic calculation methods of ship operability and safety in extreme seas. A few recent research efforts in our group have been related to this target. In one case, it was endeavored to distinguish ship high-runs from ordinary surging, by engaging the concept of instantaneous wave celerity (Spyrou et al. 2014). In another, the derivation of a practical metric for the probability of high-run was pursued (Belenky et al. 2016). Also, high-run and broaching-to statistics were produced through a direct approach based on assigning prescriptive exceedance thresholds (Spyrou et al. 2016b). Moreover, the theory of surf-riding was extended for bichromatic waves, revealing some rather unexpected types of motion (Spyrou et al. 2018). Even richer phenomena could be conjectured for a multifrequency environment.

Probability of Ship High-Runs from Phase-Space Data

2019 ◽  
Author(s):  
Ioannis Kontolefas ◽  
Kostas J. Spyrou
Keyword(s):  
Phase Space ◽  
Coherent Structures ◽  
High Speed ◽  
Statistical Information ◽  
Motion Patterns ◽  
Following Seas ◽  
Probability Calculation ◽  
Speed Level ◽  
Surf Riding ◽  
Space Data

A clustering scheme has been applied for capturing qualitatively different surge motion patterns in the phase space. The scheme enables the identification of “high-run” incidents as soon as such motions are triggered and while their phenomenology has not yet been well developed. A “high run” is a surf-riding–like behavior, appearing in irregular following seas. The concept of finite-time coherent sets is exploited for deriving estimates of the probability of high-runs. The method is verified by identifying independently the corresponding hyperbolic Lagrangian coherent structures; then, consistency is sought between the two approaches. An important feature of the method is that it does not rely on the use of some empirical criterion for the high-run threshold, such as one based on the exceedance of an arbitrary high-speed level. Despite its computational burden, the proposed scheme offers “objective” statistical information on a ship’s high-run tendency that can be used for benchmarking simpler (approximative) probability calculation schemes.

Probability of Ship High-Runs from Phase-Space Data

2019 ◽  
Author(s):  
Ioannis Kontolefas ◽  
Kostas J. Spyrou
Keyword(s):  
Phase Space ◽  
Coherent Structures ◽  
High Speed ◽  
Statistical Information ◽  
Motion Patterns ◽  
Following Seas ◽  
Probability Calculation ◽  
Speed Level ◽  
Surf Riding ◽  
Space Data

A clustering scheme has been applied for capturing qualitatively different surge motion patterns in the phase space. The scheme enables the identification of “high-run” incidents as soon as such motions are triggered and while their phenomenology has not yet been well developed. A “high run” is a surf-riding–like behavior, appearing in irregular following seas. The concept of finite-time coherent sets is exploited for deriving estimates of the probability of high-runs. The method is verified by identifying independently the corresponding hyperbolic Lagrangian coherent structures; then, consistency is sought between the two approaches. An important feature of the method is that it does not rely on the use of some empirical criterion for the high-run threshold, such as one based on the exceedance of an arbitrary high-speed level. Despite its computational burden, the proposed scheme offers “objective” statistical information on a ship’s high-run tendency that can be used for benchmarking simpler (approximative) probability calculation schemes.

scholarly journals A structural analytic method on the phase space data of Linac 4 MV photons based on the real world

2021 ◽  
Vol 82 ◽  
pp. 109-113
Author(s):  
Zhenguo Cui ◽  
Songlin Sha ◽  
Yanling Bai
Keyword(s):  
Phase Space ◽  
Real World ◽  
Analytic Method ◽  
The Real ◽  
Space Data

Improved prediction of the threshold of surf-riding of a ship in steep following seas

2010 ◽  
Vol 37 (13) ◽  
pp. 1103-1110 ◽  
Author(s):  
Wan Wu ◽  
Kostas J. Spyrou ◽  
Leigh S. McCue
Keyword(s):  
Following Seas ◽  
Surf Riding

scholarly journals Surging of Large Amplitude and Surf-riding of Ships in Following Seas

1987 ◽  
Vol 1987 (162) ◽  
pp. 152-162 ◽  
Author(s):  
Makoto Kan ◽  
Toshihiko Saruta ◽  
Mikio Yasuno ◽  
Yasuyuki Yamakoshi ◽  
Shiro Suzuki
Keyword(s):  
Large Amplitude ◽  
Following Seas ◽  
Surf Riding

Simulation study of Landau damping near the persisting to arrested transition

2017 ◽  
Vol 83 (4) ◽  
Author(s):  
Alexander J. Klimas ◽  
Adolfo F. Viñas ◽  
Jaime A. Araneda
Keyword(s):  
Phase Space ◽  
Simulation Study ◽  
High Speed ◽  
Space Distribution ◽  
Landau Damping ◽  
Field Mode ◽  
Low Speed ◽  
Phase Space Distribution ◽  
Saturation Stage ◽  
First Time

A one-dimensional electrostatic filtered Vlasov–Poisson simulation study is discussed. The transition from persisting to arrested Landau damping that is produced by increasing the strength of a sinusoidal perturbation on a background Vlasov–Poisson equilibrium is explored. Emphasis is placed on observed features of the electron phase-space distribution when the perturbation strength is near the transition value. A single ubiquitous waveform is found perturbing the space-averaged phase-space distribution at almost any time in all of the simulations; the sole exception is the saturation stage that can occur at the end of the arrested damping scenario. This waveform contains relatively strong, very narrow structures in velocity bracketing $\pm v_{\text{res}}$ – the velocities at which electrons must move to traverse the dominant field mode wavelength in one of its oscillation periods – and propagating with $\pm v_{\text{res}}$ respectively. Local streams of electrons are found in these structures crossing the resonant velocities from low speed to high speed during Landau damping and from high speed to low speed during Landau growth. At the arrest time, when the field strength is briefly constant, these streams vanish. It is conjectured that the expected transfer of energy between electrons and field during Landau growth or damping has been visualized for the first time. No evidence is found in the phase-space distribution to support recent well-established discoveries of a second-order phase transition in the electric field evolution. While trapping is known to play a role for larger perturbation strengths, it is shown that trapping plays no role at any time in any of the simulations near the transition perturbation strength.

Experimental Research on the Surf-Riding Region for High Speed Vessels

2015 ◽  
Author(s):  
Atsuo Maki ◽  
Yoshiki Miyauchi
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Safety Assessment ◽  
Estimation Methods ◽  
Model Experiments ◽  
Size Limitation ◽  
Analytical Estimation ◽  
Free Running ◽  
Surface Combatant ◽  
Surf Riding

It is well known that surf-riding phenomenon is the prerequisite of the broaching-to in following and quartering conditions. For the safety assessment of the fast vessel such as surface combatant sand patrol crafts, the estimation of the surf-riding condition is important. Therefore, so far several experimental efforts have been made. However, in these previous researches, the free running model experiments in high speed region, i.e.up to Froude number of 0.6 or 0.7, have not been conducted because of tank size limitation. As shown in this paper, there are occurrence and disappearance boundaries of surf-riding in lower and faster region, respectively. In our study, free running model experiments are carried out in high speed region, and then both boundaries are experimentally obtained. By using obtained results, the analytical estimation methods proposed by the authors can be well validated. Furthermore, the free running model experiments in irregular seas are also conducted. Then, surf-riding phenomenon in irregular seas is also discussed.

Optimal Simultaneous Kinematic, Dynamic and Control Design of High Performance Manipulators Based on Trajectory Pattern Method

1998 ◽  
Author(s):  
J. Rastegar ◽  
L. Liu ◽  
M. Mattice
Keyword(s):  
High Speed ◽  
High Performance ◽  
Optimality Criterion ◽  
Control Design ◽  
Tracking Errors ◽  
Motion Patterns ◽  
Trajectory Pattern ◽  
And Control ◽  
Velocity Tracking ◽  
Trajectory Pattern Method

Abstract An optimal simultaneous kinematic, dynamic and control design approach is proposed for high performance computer controlled machines such as robot manipulators. The approach is based on the Trajectory Pattern Method (TPM) and a fundamentally new design philosophy that such machines in general and ultra-high performance machines in particular must only be designed to perform a class or classes of motions effectively. In the proposed approach, given the structure of the manipulator, its kinematic, dynamic and control parameters are optimized simultaneously with the parameters that describe the selected trajectory pattern. In the example presented in this paper, a weighted sum of the norms of the higher harmonics appearing in the actuating torques and the integral of the position and velocity tracking errors are used to form the optimality criterion. The selected optimality criterion should yield a system that is optimally designed to accurately follow the specified trajectory at high speed. Other objective functions can be readily formulated to synthesize systems for optimal performance. The potentials of the developed method and its implementation for generally defined motion patterns are discussed.

scholarly journals A dynamic zone estimation method using cumulative voxels for autonomous driving

2017 ◽  
Vol 14 (1) ◽  
pp. 172988141668713 ◽  
Author(s):  
Seongjo Lee ◽  
Seoungjae Cho ◽  
Sungdae Sim ◽  
Kiho Kwak ◽  
Yong Woon Park ◽  
...  
Keyword(s):  
High Speed ◽  
Moving Objects ◽  
Three Dimensional ◽  
Estimation Method ◽  
Autonomous Driving ◽  
Significant Feature ◽  
Data Set ◽  
Ground Truth Data ◽  
Unmanned Vehicle ◽  
Space Data

Obstacle avoidance and available road identification technologies have been investigated for autonomous driving of an unmanned vehicle. In order to apply research results to autonomous driving in real environments, it is necessary to consider moving objects. This article proposes a preprocessing method to identify the dynamic zones where moving objects exist around an unmanned vehicle. This method accumulates three-dimensional points from a light detection and ranging sensor mounted on an unmanned vehicle in voxel space. Next, features are identified from the cumulative data at high speed, and zones with significant feature changes are estimated as zones where dynamic objects exist. The approach proposed in this article can identify dynamic zones even for a moving vehicle and processes data quickly using several features based on the geometry, height map and distribution of three-dimensional space data. The experiment for evaluating the performance of proposed approach was conducted using ground truth data on simulation and real environment data set.

TU-AB-BRC-05: Creation of a Monte Carlo TrueBeam Model by Reproducing Varian Phase Space Data

2016 ◽  
Vol 43 (6Part32) ◽  
pp. 3730-3730 ◽  
Author(s):  
K O'Grady ◽  
S Davis ◽  
J Seuntjens
Keyword(s):  
Monte Carlo ◽  
Phase Space ◽  
Space Data
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