Ship Model Research Articles

Multi-beam Line-finding Problem Based on Geometric Model

In this paper, a geometric model is established to study the problem of multi-beam sounding line deployment. In this paper, the index of multi-beam sounding is calculated firstly. The geometric model of the path of the acoustic signal transmitted by the measuring ship and the transducer of the measuring ship, the seabed slope and the plane perpendicular to the direction of the measuring line are established. The mathematical relationship between the coverage width W of multi-beam sounding and the overlap rate between adjacent strips is obtained, and the overlap rate between adjacent strips is calculated. Finally, the model is tested to meet the robustness and the model is correct. Secondly, this paper studies the coverage width W of multi-beam sounding. According to the two cases that the coverage width W has nothing to do with the slope of the seabed and the coverage width W has something to do with the slope of the seabed, the geometric models of the measurement ship, the path of the acoustic signal emitted by the transducer of the measurement ship, the seabed slope and the plane perpendicular to the direction of the survey line are established respectively, and the geometric model is tested. The model is correct.

Fault-tolerant controller based on artificial intelligence combined with terminal sliding mode and pre-described performance function applied on ship dynamic position stabilization systems

The presented study, develops an intelligent fault-tolerant controller to automatically control and maintain the position of a ship. The controller possesses the capabilities of holding the ship steady at a fixed position, automatically transferring the ship from one point to another, and tracking a target in the presence of various disturbances, uncertainties in the ship model, and thruster faults. A backstepping control approach based on the Terminal Sliding Mode method is employed to improve the accuracy of the controller. The aforesaid method guarantees time-limited convergence without relying on the initial conditions of system. A pre-described performance function (PPF) is utilized to ensure the performance in transient states and the calculations, which leads to the specific equations achievement for the study, which guarantees the system's stability. Environmental disturbances, uncertainties, and thruster faults are estimated using a Radial Basis Neural Network, allowing the controller to adapt to changes in the ship's environment and system uncertainties. The designed controller is proven to ensure the tracking error remains within a predefined range and can stabilize the ship system within a constant time without being influenced by the initial conditions. This stability is achieved in the presence of environmental disturbances, model uncertainties, and thruster faults, and the tracking error converges to a neighborhood near the origin. The controller is verified using a ship mode in the MATLAB environment, and the results show that the designed controller effectively controls the ship's position. The theoretical findings are successfully verified through these simulation tests.

Numerical Analysis and Validation of an Optimized B-Series Marine Propeller Based on NSGA-II Constrained by Cavitation

Constantly growing environmental concerns focused on reducing pollution, in addition to rising fuel costs in recent years, have led the maritime industry to develop and implement fuel-saving solutions. Among them is the optimization of marine propeller efficiency, as marine propellers are a crucial part of ship’s propulsion system. During the initial design stage, selecting the optimal propeller is considered a multi-objective optimization process. This research focused on maximizing propeller open water efficiency, while minimizing engine brake power constrained by thrust and cavitation. Optimization was applied to Wageningen B-series propellers and conducted using the Non-Dominated Sorting Genetic Algorithm II (NSGA-II). The algorithm selected optimum parameters to create the propeller model, which was then evaluated numerically through computational fluid dynamics (CFD) with a multiple reference frame (MRF) and under the SST k-ω turbulence model, to obtain the open water hydrodynamic characteristics. In addition, the cavitation effect was evaluated using the Zwart–Gerber–Belamri cavitation model. The numerical model results were validated through comparison with open water experimental data from the Netherlands Ship Model Basin for the Wageningen B-series propellers. The results showed errors of 3.29% and 2.01% in efficiency under noncavitating and cavitating conditions, respectively. Correct performance of the functions was shown, based on neural networks trained to estimate thrust and torque coefficients instead of polynomials. The proposed optimization process and numerical model are suitable for solving multi-objective optimization problems in the preliminary design of fixed-pitch marine propellers.

Wall shear stress measurement of turbulent bubbly flows using laser Doppler displacement sensor

A novel wall shear stress meter is developed to promote studies of frictional drag reduction by injecting air bubbles into a turbulent boundary layer. Such studies require a tool having a time resolution sufficiently high to capture the unsteady effect of turbulent characteristics due to various bubble passage patterns. The present study adopts the principle of the heterodyne interferometer to capture of time variation of wall shear stress in turbulent flow up to 500 Hz in sampling frequency. We demonstrate the performance of the tool by applying it to bubbly flows beneath a flat-bottom model ship running at 3 m/s in a towing water reservoir, where bubbles experience wavy passage around a few Hz in frequency. The data obtained by the proposed shear stress meter agree well with Dean's formula for single-phase turbulent channel flow. The scattering of the data across three trials is sufficiently small, at approximately 3 %. This high reproducibility is a great advantage over conventional direct measurements, which have low reproducibility and a large scatter of the data of approximately 15 %. The obtained results represent reasonable drag reductions by injecting bubbles with different void fractions. We also evaluate histogram of the wall shear stress fluctuation to characterize the effect of drag reduction by unsteady passage of bubbles.

Power Positioning System Control Study of “Intelligent Research and Internship Vessel” Based on Terminal Sliding Mode

As most of the current dynamic positioning systems are based on model ships, they cannot accurately reflect the motion state, position changes, and mutual influence of each part of the dynamic positioning system of actual ships in complex environments. Other actual ships such as cargo ships cannot add various sensors and auxiliary equipment to verify and analyze the positioning system. This article takes the intelligent research and training dual-use ship of Dalian Maritime University, which integrates scientific research and training, as the object of study. This ship will not be affected by the voyage period and route and can choose a suitable sea area for research. Therefore, in order to improve the accuracy and reliability of the dynamic positioning system, research on the ship’s dynamic positioning system was carried out. Firstly, an accurate mathematical model was developed to simulate ship motion, focusing on the use of the Dalian Maritime University’s intelligent and practical training dual-purpose vessel as the modeling object. Through this approach, a more detailed understanding of the effects of actual environmental perturbations on ship control and positioning can be obtained, as well as more realistic ship control and positioning results. The hydrodynamic derivatives of ship model motion were obtained by numerical calculation and applied to the three-degree-of-freedom model of the intelligent research and training dual-use ship. Then, the model was used as part of the closed-loop simulation model of the ship’s dynamic positioning system, and the terminal sliding mode controller was used for simulation and emulation, thereby obtaining ideal simulation test results. Our results deepen the understanding of DPS accuracy and are consistent with the theory of terminal slip modes for ship power positioning control systems. This has implications for improving the accuracy of ship power positioning systems, as previously discussed in previous authors. In conclusion, this study not only improves the accuracy and reliability of the DPS but also proposes the use of the terminal slip film for a ship power positioning control system modeled on the Dalian Maritime University intelligent and practical dual-purpose vessel. These contributions are significant in improving the efficiency, safety, and environmental sustainability of ship operations.

Time-prior-based stacking ensemble deep learning model for ship infrared automatic target recognition in complex maritime scenarios

In complex maritime scenarios, ship infrared (IR) data shows diverse feature distributions due to the variation of target pose, behavior, and environmental factors. These factors pose challenges for feature learning in automatic target recognition (ATR) models. Furthermore, ATR models based on different mechanisms exhibit performance disparities, making it difficult to obtain a model that demonstrates optimal generalization across all scenarios. Therefore, this paper proposes a time-prior-based stacking ensemble deep learning model (TPSM) that integrates features extracted by multiple deep learning-based base models and leverages a meta model to inherit these features for complementary advantages. Simultaneously, to mitigate the adverse effects of complex spatial distribution within the dataset, the training set is partitioned into samples characterized by distinct time attributes (e.g., day, night, and mixed). Base models are then trained and selected from these diverse time attribute samples to construct the ensemble framework. The results indicate that TPSM achieved an Accuracy performance of 95.46% on high-fidelity simulated data, surpassing individual base models and other ensemble learning methods. Finally, we employ some explainable artificial intelligence (XAI) techniques to visualize the learning features of the TPSM, thereby validating the credibility of feature extraction.

A novel adaptive synchronization algorithm for a general class of fractional-order complex-valued systems with unknown parameters, and applications to circuit realization and color image encryption

This article proposes an adaptive synchronization (AS) algorithm to synchronize a general class of fractional-order complex-valued systems with completely unknown parameters, which may appear in physical and engineering problems. The analytical and theoretical concepts of the algorithm rely on the mathematical framework of the Mittag-Leffler global stability of fractional-order systems. A specific control system is established analytically based on the fractional-order adaptive laws of parameters, and the corresponding numerical results are executed to verify the accuracy of the AS algorithm. The proposed synchronization method is evaluated using the fractional-order complex Rabinovich system as an attractive example. The electronic circuits of the new system with different fractional orders are designed. By utilizing the Multisim electronic workbench software, various chaotic/hyperchaotic behaviors have been observed, and a good agreement is found between the numerical results and experimental simulation. In addition, the approximation of the transfer function for different fractional-order are presented. And the corresponding resistor and capacitor values in the chain ship model (CSM) are estimated, which can be utilized in designing electronic circuits for other fractional-order systems. Furthermore, two strategies for encrypting color images are proposed using the AS algorithm and fractional-order adaptive laws of parameters. In the first strategy, the color image is treated as a single package and divided into two vectors. The first vector is embedded into transmitter parameters, while the second vector is injected into the transmitter state signals. In the second strategy, the primary RGB channel components of the original color image are extracted and separated into two vectors, and the same process is followed as in the first strategy. These strategies complicate the decryption task for intruders. Different scales of white Gaussian noise are added to color images to examine the robustness of the proposed color images encryption strategies.

A Review on Motion Prediction for Intelligent Ship Navigation

In recent years, as intelligent ship-navigation technology has advanced, the challenge of accurately modeling and predicting the dynamic environment and motion status of ships has emerged as a prominent area of research. In response to the diverse time scales required for the prediction of ship motion, various methods for modeling ship navigation environments, ship motion, and ship traffic flow have been explored and analyzed. Additionally, these motion-prediction methods are applied for motion control, collision-avoidance planning, and route optimization. Key issues are summarized regarding ship-motion prediction, including online modeling of motion models, real ship validation, and consistency in modeling, optimization, and control. Future technology trends are predicted in mechanism-data fusion modeling, large-scale model, multi-objective motion prediction, etc.

Numerical Study on the Influence of Water Depth on Air Layer Drag Reduction

Over the years, air lubrication technology has been widely applied to maritime vessels, demonstrating its significant energy-saving and emission-reducing effects. However, the application of this technology in inland waterway transportation faces unique challenges due to the shallower water depths, particularly during low water periods. Under such conditions, the formation of the air layer and its associated drag-reduction effects may undergo alterations. Conducting research on air lubrication technology in shallow water conditions holds great practical significance for promoting its application in inland waterway vessels. Therefore, a numerical study is undertaken to examine the impact of water depth on Air layer Drag Reduction (ALDR) to promote the use of ALDR technology on inland canal boats with shallow water depths. The object was a specific river-sea direct ship model, and a groove was created at the bottom of the model with air injection. At two distinct speeds, numerical simulations were run for four different depths: deep water, moderate water, shallow water, and ultra-shallow water. A comparative examination of the air layer morphology on the ship bottom and drag reduction was conducted to investigate the impact of water depth on ALDR and confirm the viability of using ALDR technology on shallow-water navigation boats. The results indicate that due to the change in the velocity and pressure fields at the bottom of the ship, the efficiency of drag reduction and the form of the air layer on the ship’s bottom are significantly impacted by variations in water depth in restricted waters. However, the total resistance can still be significantly reduced by setting grooves on the hull with air injected in shallow waterways. Reduced frictional resistance no longer predominates the overall resistance reduction in shallow water; the proportion of the decrease in viscous pressure resistance rises and can reach up to 4.8 times the decrease in frictional resistance. The research confirms the application prospects of this technology on inland waterway transport ships.

Experimental study of the resistance of a hydrofoil supported watercraft (hysuwac)

A possible alternative to reduce fuel consumption on a ship is through energy efficiency. For this purpose, a hydrofoil supported watercraft (hysuwac) utilizes two hydrofoils, one installed near the bow and the other near the stern of the catamaran, to reduce the vessel’s resistance. To investigate the effectiveness of the hydrofoils, CFD calculations were conducted in an earlier study. The purpose of this study is to provide experimental data to validate the CFD calculation results reported earlier for which towing tests were conducted at the Laboratory of Ship Hydrodynamics, ITS Surabaya, Indonesia. The ship model was made by using a three-dimensional print, which is then assembled into a ship model that meets the test requirements. The hydrofoil used has a NACA 641-212 section with an angle of attack of 4°. Twelve variations of towing tests were carried out with six variations of speed and two conditions, namely catamaran without and with foil system. A comparison between the CFD and experimental results shows that the CFD results are consistent with the experimental data. The minimum magnitude of percentage difference between the CFD results and experimental data is 1.14%, while the maximum magnitude of this is 16.79%. The observed difference is ascribed mainly to scale effects.

Modeling and simulation analysis of ship 6-dof simulation swing platform based on matlab

In this paper, the kinematics and dynamics model of the ship’s six-degree-of-freedom simulation swing platform were studied. Then, a random wave and ship motion response model was established, and a six-degree-of-freedom motion model of DP ship in four-level sea state was established and studied by using the open source MSS toolbox, which lays a foundation for the subsequent simulation and control strategy research. The ordinary PID controller and fuzzy PID controller were designed and simulated, and the results were compared to verify the effect of fuzzy PID controller.

Active control of target sound fields using structural-acoustic brightness applied to a ship model's acoustic signature.

This manuscript presents a method for reproducing sound fields actively by using a vibrating submerged structure as the field reproduction source, with the target sound field to be reproduced defined in the frequency domain using the acoustic brightness approach. To balance the predetermination of a mono- or multi-zone target sound pressure field and the control effort required, singular value decomposition of the structural-acoustic system matrix is proposed. The dependency of the radiation efficiency into the target zone on the singular modes representing source and pressure modes is investigated using a wavenumber-domain approach. Furthermore, a feedforward control principle is adopted for adaptive sound-field reproduction with mode matching from the least squares perspective. Finally, an experiment is reported that involve synthesizing a tonal target underwater acoustic signature of a model of a fast attack craft (scale 1:8) at a measurement facility at Lake Plön in Germany. The results show that with the structural-acoustic brightness approach structural modes with radiation coupling into the target zone are excited and related pressure modes exhibit individual focus in the direction of hydrophones in use. Finally, a predetermined narrowband sound pressure field is actively reproduced at the hydrophone positions using inertial actuators and accelerometers on the ship model's hull.

Развитие образцов отечественного корабельного вооружения, представленного в моделях кораблей из собрания Центрального военно-морского музея имени императора Петра Великого

The article attempts for the first time to consider ship models not only as sources on the history of shipbuilding in general but also on ship weapons in particular. The relevance of the work lies in the importance of preserving the material and historical heritage of the Russian fleet, and insufficient coverage in historical science of the experience of using ship models in the interests of the Navy. The Central Naval Museum has a significant collection of ship models, ship mechanisms, and naval weapons, according to which, due to the accurate transfer of appearance, design, scale, and careful detailing of the elements and parts of weapons, it is possible to study a particular period in the history of the fleet and the development of weapons. Thus, a model of a warship, being in the halls of a museum or in the storage, does not lose its function as an element of the project, while remaining a historical relic, an artifact of shipbuilding thought, and often an object of decorative and applied art. Materials stored in museums can serve practical purposes. Using these examples, new generations of Russians get acquainted with the visible chronicle of the Navy and the destinies of remarkable ships within the walls of the museum. The purpose of the article is to attract attention to objects from the museum’s collection not only of specialists in the field of naval history, shipbuilders, and design engineers but also of people interested in the fleet. The paper aims to establish a connection between the accumulated experience of ancestors and the work of contemporaries. The author used the historical-comparative method traditionally applied in historical science, which allows us to talk about the development of classes and types of ships, as well as naval weapons, in the domestic fleet. As a result of the study, the author offers a new look at widely and little-known facts from the history of our fleet and presents a modern understanding of the study of ship models. The most striking examples of such objects from the museum collection are shown.

Energy and exergy analysis of hydrogen production from seawater using waste heat recovery system on a model ship

Energy and exergy analysis of hydrogen production from seawater using waste heat recovery system on a model ship

Energy and Exergy Analysis of Hydrogen Production from Seawater Using Waste Heat Recovery System on a Model Ship

Energy and Exergy Analysis of Hydrogen Production from Seawater Using Waste Heat Recovery System on a Model Ship

Model-based Reinforcement Learning for Ship Path Following with Disturbances

Modelling and control of ships is a challenging task due to their intrinsic nonlinearities and high uncertainty. In the complex and dynamic sea environment, the efficacy of well-designed motion controllers diminishes significantly. To achieve optimal performance, high-performance motion control systems must possess the ability to adapt to diverse working conditions, repel external disturbances, and incorporate learning capabilities. In addressing critical computational challenges encountered in the real-world deployment of autonomous driving agents, Reinforcement Learning (RL) methods have been effectively employed. This paper proposed a reinforcement learning control method for ship path following based on an environmental disturbance model. RL is utilized to learn the dynamic properties of the system to resist environmental disturbances. Experimental results show that the method can follow the path with acceptable accuracy and high robustness.

Waves filtering in heading controllers: impact on the power production of an energy ship

This article investigates the impact on power production of an energy ship of two types of heading controllers. The first controller includes a filter which eliminates the wave-frequency dependent motion of the ship, while the other aims at compensating the effects of waves on the motion of the ship. The study is based on a numerical model of the energy ship which is presented in the paper. Results show that waves compensation reduces the generated power variation but increases rudder oscillations. In the opposite, the waves filtering controller allows for a slightly greater power production at the expense of greater power variations.

Enhancing Line-of-Sight Guidance to Improve Path Following for Marine Surface Vessels

This paper highlights and addresses several deficiencies with line-of-sight guidance not commonly discussed in the literature. We consider the path-following problem for marine surface vessels following smooth paths defined by a set of waypoints. Motivated by key shortcomings in state-of-the-art adaptive and integral line-of-sight guidance algorithms, we propose a novel guidance law with three main features. First, it incorporates a novel update law for the crab-angle estimate based on course error injection instead of cross-track error. Second, we add a feedforward signal for pivot point compensation. Last, the coupling with the underlying heading control system is properly treated by supplying acceleration, rate-of-turn, and heading setpoints derived from both the path formulation and the line-of-sight guidance scheme. A case study using a high-fidelity model of a research ship demonstrates the discussed deficiencies using popular line-of-sight formulations from the literature. It shows that the proposed design has marked improvements over these. We argue that the proposed design sets a benchmark for path-following performance for marine surface vessels.

A digital twin for ship structures—R&D project in Japan

Abstract In order to clarify and visualize the real state of the structural performances of ships in operation and establish a more optimal, data-driven framework for ship design, construction and operation, an industry-academia joint R&D project on the digital twin for ship structures (DTSS) was conducted in Japan. This paper presents the major achievements of the project. The DTSS aims to grasp the stress responses over the whole ship structure in waves by data assimilation that merges hull monitoring and numerical simulation. Three data assimilation methods, namely, the wave spectrum method, Kalman filter method, and inverse finite element method were used, and their effectiveness was examined through model and full-scale ship measurements. Methods for predicting short-term extreme responses and long-term cumulative fatigue damage were developed for navigation and maintenance support using statistical approaches. In comparison with conventional approaches, response predictions were significantly improved by DTSS using real response data in encountered waves. Utilization scenarios for DTSS in the maritime industry were presented from the viewpoints of navigation support, maintenance support, rule improvement, and product value improvement, together with future research needs for implementation in the maritime industry.

Low-noise multi-channel underwater electric field measurement and analysis system for a ship model.

The underwater electric field (UEF) signature of a ship is a key factor in its survivability in marine warfare. Moreover, the study of a ship's UEF using scale models of ships in pools can be useful for the design of electromagnetically stealthy ships. Aiming at the system requirement of measuring and analyzing the UEF of scale models of ships with low noise, many channels, and real-time responsivity, we developed a system consisting of electrode sensors, a measuring device, and a personal computer (PC). Small Ag/AgCl electrodes with low noise and high stability were used. The measuring device was capable of simultaneously amplifying, sampling, and storing 24 channels of UEF data in real-time, and it was connected to the PC via Ethernet to facilitate the transfer of UEF data at high speeds. The PC software could display 24 low-frequency UEF curves in real time and perform spectral analysis and filtering of the UEF signals. In system performance tests, we found that the system had a noise floor lower than 6.34 nV/rt(Hz)@1Hz and could simultaneously sample 24 channels of UEF signals while storing, displaying, and analyzing the signals in real-time. The primary functions of the system were also validated in a pooled experiment.