Prediction Of Ship Research Articles

Prediction of Ship's Speed Through Ground Using the Previous Voyage's Drift Speed

Prediction of Ship's Speed Through Ground Using the Previous Voyage's Drift Speed

Machine learning enhancement of manoeuvring prediction for ship Digital Twin using full-scale recordings

Digital Twins have much attention in the shipping industry, attempting to support all phases of a vessel’s life cycle. With several tools appearing in Digital Twin software suites, high-quality manoeuvring and performance prediction remain cornerstones. Propulsion efficiency is in focus while in service. Simulator-based training is in focus to ensure safety of manoeuvring in confined waters and harbours. Prediction of ships’ velocity and turn rate are essential for correct look and feel during training, but phenomena like dynamic inflow to propellers, bank and shallow water effects limit simulators’ accuracy, and master mariners often comment that simulations could be in better agreement with actual behaviours of their vessel. This paper focuses on digital twin enhancements to better match reality. Using data logged during in-service operation, we first consider a system identification perspective, employing a first-principles model structure. Showing that a complete first-principles model is not identifiable under the excitation met in service, we employ a Recurrent Neural Network to predict deviations between measured velocities and the model output. The outcome is a hybrid of a first-principles model with a machine learning generic approximator add-on. The paper demonstrates significant improvements in prediction accuracy of both in-harbour manoeuvring and shallow water passage conditions.

CFD investigation into resistance characteristics of a pusher-barge system in calm water

Prediction of ship’s total resistance of a pusher-barge system has become enormous complexity involving nonlinear-hydrodynamic flows behaviour along their hull forms. Both of empirical and simplified numerical solutions may still lead into inaccurate results due to presence of nonlinear characteristics of the pressure and viscous resistances. The use of a more sophisticated method would obviously necessitate to solve the above problem. This paper presents a Computational Fluid Dynamics (CFD) approach to predict the total ship’s resistance of a pusher-barge system at various barge’s configurations. To achieve such objective, four different configurations of the barge models incorporated with various Froude numbers have been taken into account in the computational simulation. In general, the results revealed that the increase of Froude number (Fr = 0.182 to 0.312) was proportional to the magnitude of RT, RP and RV. Regardless of the various Froude number, the pusher-barge system with a 13BP configuration provides the highest resistance compared to the 12BP and 11BP. In addition, the arrangement of barges in the longitudinal (12BP) and lateral (21BP) configurations produced a significant effect with increases in RT, RP and RV values of 110%, 167.5% and 77.6%, respectively. The possible reason for this is that the increase of the total wetted surface area for 21BP has produced to a proportionally higher amount of the pressure and viscous resistance. Overall study, the numerical results were presented and analysed based on few aspects involved the total resistance and resistance coefficient in terms of pressure and viscous resistance of the pusher-barge system. This analysis provides very valuable information on choosing the most reliable arrangement of pusher-barge system. This analysis provides very valuable information on choosing the most reliable arrangement of pusher-barge system

Prediction of ships’ speed-power relationship at speed intervals below the design speed

• 50,000 noon reports from 88 tankers analysed to assess speed-power relationship • Data-driven model combining principles from naval architecture and econometrics • Speed-power exponent is significantly lower than 3 at speeds below the design speed • Environmental effect of slow steaming is overestimated • Imparts attention to speed optimization and not reduction for reducing CO 2 emissions This study investigates the speed-power relationship of ships, and is based on a combined econometric and naval architectural data-driven model fed with operational data from more than 50,000 noon reports obtained from 88 tankers. It is shown that the speed-power exponent is significantly lower than 3 at speed intervals below the design speed. This finding, including the study itself, affects the environmental discussions related to slow steaming, since it implies that slow steaming will not be as good as often stated. As such, the study imparts attention to speed optimisation, rather than reduction, in the political and environmental debate focused on the reduction of carbon emissions from shipping.

Ship Trajectory Prediction Based on Bi-LSTM Using Spectral-Clustered AIS Data

According to the statistics of maritime accidents, most collision accidents have been caused by human factors. In an encounter situation, the prediction of ship’s trajectory is a good way to notice the intention of the other ship. This paper proposes a methodology for predicting the ship’s trajectory that can be used for an intelligent collision avoidance algorithm at sea. To improve the prediction performance, the density-based spatial clustering of applications with noise (DBSCAN) has been used to recognize the pattern of the ship trajectory. Since the DBSCAN is a clustering algorithm based on the density of data points, it has limitations in clustering the trajectories with nonlinear curves. Thus, we applied the spectral clustering method that can reflect a similarity between individual trajectories. The similarity measured by the longest common subsequence (LCSS) distance. Based on the clustering results, the prediction model of ship trajectory was developed using the bidirectional long short-term memory (Bi-LSTM). Moreover, the performance of the proposed model was compared with that of the long short-term memory (LSTM) model and the gated recurrent unit (GRU) model. The input data was obtained by preprocessing techniques such as filtering, grouping, and interpolation of the automatic identification system (AIS) data. As a result of the experiment, the prediction accuracy of Bi-LSTM was found to be the highest compared to that of LSTM and GRU.

Study on prediction of ship’s power using light GBM and XGBoost

Study on prediction of ship’s power using light GBM and XGBoost

Acoustic localization of incipient cavitation in marine propeller using greedy-type compressive sensing

A precise evaluation of propeller cavitation inception is imperative in prediction of ship's underwater radiated noise performance. In addition to a simple indication on whether the cavitation has occurred or not, it would be much more valuable if the location of cavitation occurrence can be identified for a further confirmation. Hence, this work concentrates on establishing an efficient acoustic localization for incipient cavitation using the compressive sensing (CS) theory. Rather than the convex minimization approach, the greedy-type orthogonal matching pursuit (OMP) algorithm is chosen for solving the CS localization problem due to a low computational complexity making it suitable for online applications. It is also proposed to employ the singular value decomposition (SVD) - based rank estimation for a provision of user input parameter that is essential for initializing the greedy algorithm. The suggested localization procedure is validated through the propeller cavitation data obtained in a water tunnel facility.

Numerical Analysis of Full-Scale Ship Self-Propulsion Performance with Direct Comparison to Statistical Sea Trail Results

Accurate prediction of the self-propulsion performance is one of the most important factors for the energy-efficient design of a ship. In general, the hydrodynamic performance of a full-scale ship could be achieved by model-scale simulation or towing tank tests with extrapolations. With the development of CFD methods and computing power, directly predict ship performance with full-scale CFD is an important approach. In this article, a numerical study on the full-scale self-propulsion performance with propeller operating behind ship at model- and full-scale is presented. The study includes numerical simulations using the RANS method with a double-model and VOF (Volume-of-Fluid) model respectively and scale effect analysis based on overall performance, local flow fields and detailed vortex identification. The verification study on grid convergence is also performed for full-scale simulation with global and local mesh refinements. A series of sea trail tests were performed to collect reliable data for the validation of CFD predictions. The analysis of scale effect on hull-propeller interaction shows that the difference of hull boundary layer and flow separation is the main source of scale effect on ship wake. The results of the fluctuations of propeller thrust and torque along with circulation distribution and local flow field show that the propeller’s loading is significantly higher for model-scale ship. It is suggested that the difference of vortex evolution and interaction is more pronounced and has larger effects on the ship’s powering performance at model-scale than full-scale according to the simulation results. From the study on self-propulsion prediction, it could be concluded that the simplification on free surface treatment does not only affect the wave-making resistance for bare hull but also the propeller performance and propeller induced ship resistance which can be produced up to 5% uncertainty to the power prediction. Roughness is another important factor in full-scale simulation because it has up to an approximately 7% effect on the delivery power. As a result of the validation study, the numerical simulations of full-scale ship self-propulsion shows good agreement with the sea trail data especially for cases that have considered both roughness and free surface effects. This result will largely enhance our confidence to apply full-scale simulation in the prediction of ship’s self-propulsion performance in the future ship designs.

Analysis of uncertainties in the prediction of ships’ fuel consumption – from early design to operation conditions

ABSTRACTThis investigation presents an approach towards a better understanding of achievable accuracy of fuel consumption predictions of ships and provides an example of how a thorough uncertainty analysis of prediction models can be performed. A generic ship energy systems model is used for the fuel consumption prediction of two reference ships: a RoRo ship and a tanker. The study presents how uncertainties can be categorised and handled in four different phases of a ship's life – from early design to ship operation. Monte Carlo simulations are carried out for two environmental conditions to calculate the mean and uncertainty of the fuel consumption. The results show that the uncertainty in the fuel consumption prediction in a very early phase of the design process is approximately 12%, whereas at a very late phase, it reduces to less than 4%. Finally, the simulation model is applied to a real ship during operation conditions.

Prediction of ships' position by analysing AIS data: an artificial intelligence approach

Maritime domain awareness deals with the situational understanding of maritime activities that could impact security, safety, the economy, or the environment. Nowadays, with the constant increase in maritime traffic, navigation security has become one of the most relevant and challenging issues in the maritime domain. This growth of maritime traffic has led to technological advances and new maritime regulations aiming to boost the safety of navigation. In that vein, use of the automatic identification system (AIS), a maritime safety and vessel traffic system, is now imposed by the International Maritime Organization. The system broadcasts position reports and short messages with information about a ship and its voyage (vessel identity, position, speed, course and destination). In this paper, a computational intelligence system able to predict the future position of a vessel using AIS data is proposed. The system is based on a recently defined variant of genetic programming that integrates semantic awareness into the search process. This system is compared with other state-of-the-art computational intelligence methods, showing its suitability for addressing the problem at hand.

Direct calculation method of roll damping based on three-dimensional CFD approach

The effect of roll damping on the prediction of a ship's motion is significant. A method based on the 3-D CFD approach for calculating the roll damping of a ship is proposed in this paper. The free decay experiments of 4 different types of ships at zero velocity are carried out. The roll damping coefficients are calculated and compared with the experiment results, with a good agreement. It is shown that the method adopted in this paper could be used to simulate the free rolling of a ship in the calm water at zero velocity very well and with good, stable accuracy for the prediction of the roll damping, and also with good applicability. This method may be further developed for the prediction of a full scale ship in the future.

Computational Fluid Dynamics and Numerical Acoustic Response for Ship Accommodation Areas due to Propeller Excitation, towards a Human Factors Recommendations

In order to achieve the acoustic comfort design for ship accommodation areas, This paper introduces the noise prediction of ship’s superstructure cabins based on boundary element method (BEM). The study investigates the ship acoustic responses due to fluctuating forces induced as a result of interaction between a 4-bladed propeller and Bulk Carrier ship 35,000DWT at full scale. The mathematical models for the ship and the propeller have been built and validated using computational fluid dynamics (CFD), then unsteady simulation done to obtain the transient responses of the propeller excitations. Finally, the acoustic responses of ship super structure under propeller excitations are predicted using BEM in time domain. This work shows a numerical method enable to measure the structural and acoustic responses of the ship at propeller rotating speeds. In addition, at the structural resonating modes of the propeller and the ship. As the propulsion system is the main source of the ship exciting forces thereby nowadays prediction of the ship low frequency noise due to propulsion system becomes important to naval designer for designing a comfort accommodation areas for the crew onboard the ship.

A New Method for Accurate Prediction of Ship's Inertial Stopping Distance

A New Method for Accurate Prediction of Ship's Inertial Stopping Distance

Dynamic Response Analysis of Small Oil Tanker Based on AQWA

Ship navigation performance more and more attention in real sea conditions.To study the properties of ship motion in waves, Applling hydrodynamics calculation software for AQWA-line and AQWA-AGS modules and taking into account the role of random wave load, 2450DWT a small oil tanker in simulation and analysis of a campaign response under sea conditions, Calculate shipping in several waves under the angle of vertical and horizontal swing, heave, pitch, roll and the first rolling response amplitude operators of RAOs, additional parameters such as quality and radiation damping. Application of spectrum analysis method, ITTC wave with two parameters, which strike the spectral density of ship motion, and finally using Excel to calculate sprawling forecast prediction of ship under irregular wave.

Numerical Calculation of Added Mass for Ship Dynamic Stability by High Order Panel Method

IMO Standards for ship maneuverability require prediction of ship’s maneuvering performance at the design stage. For this purpose, various methods such as those based on free running model tests, captive model tests or numerical simulation using mathematical models can be used. While this paper describes a numerical method for estimating ship’s dynamic stability by computing the linear sway and yaw added mass coefficients using a higher-order panel method based on Non-Uniform Rational B-Spline. Three dimensional forward-speed radiation problems are formulated and solved in frequency domain. The linear hydrodynamic coefficients are calculated and preliminary results are presented for a modified Wigley hull.

Database System Approach for Maneuvering Performance Prediction

A study on the database system aimed at the prediction of ship's maneuverability has been carried out. The database system covering full-scale ship's performance, hydrodynamic ship model data and ship geometry is presented. The full scale ship maneuvering performance data and model hydrodynamic data are analyzed here. The results are explained by comparison with series ship model test data. It is pointed out that the use of the database system has limited accuracy if only ship's main particulars are used for the database access. To remedy this situation, an idea of using a type ship concept for improvement of the maneuverability prediction is proposed.

Statistical Prediction of Ship’s Effective Power Using Theoretical Formulation and Historic Data

This paper reports on the progress in developing a tool that easily provides reliable resistance predictions for all candidate hull forms, using only the geometric information available at an early stage of design development. Parallel to model testing, the methodology is based on Froude's hypothesis. However, the residuary resistance is now predicted by a technique that combines a theoretical formulation for wave resistance and form drag with a statistical regressional analysis of a historic model-test database. The theoretical formulation accounts for the basic physics, while the regressional analysis provides the quantitative answers. The merit of the present tool is evaluated through comparison with other existing techniques and through its application to several actual hull designs.