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    Naval Architecture and Ocean Engineering
    Solution to Long-Range Continuous and Precise Positioning in Deep Ocean for Autonomous Underwater Vehicles Using Acoustic Range Estimation and Inertial Sensor Measurements
    YANG Tao (杨 涛), ZHAO Jiankang∗ (赵健康)
    2022, 27 (3):  281-297.  doi: 10.1007/s12204-022-2441-6
    Abstract ( 221 )   PDF (2619KB) ( 125 )  
    Although advances in research into autonomous underwater vehicles (AUVs) have been made to extend their working depth and endurance, underwater experiments and missions remain to be restricted by the positioning performance of AUVs. With the Global Navigation Satellite System (GNSS) precluded due to the rapid attenuation of radio signals in underwater environments, acoustic positioning methods serve as an effective substitution. A long-range continuous and precise positioning solution for AUVs in deep ocean is proposed in this study, relying on acoustic signals from beacons at the same depth and aided by onboard inertial sensors. A signal system is investigated to provide time of arrival (TOA) estimation in a resolution of milliseconds. Without pre-knowledge or local measurement of the accurate sound speed, an AUV is enabled to continuously locate its horizontal position based on rough ranges estimated by an iterative least square (ILS) based algorithm. For better accuracy and robustness, range deviations are compensated with a reference point of known position and outliers in the trajectory are eliminated by an implementation of the extended Kalman filter (EKF) coupled with the state-acceptance filter. The solution is evaluated in simulation experiments with environmental information measured on the spot, providing an average position error from ground truth below 10 m with a standard deviation below 5 m.
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    Modification Method of Longitudinal Bow Structure for Ice-Strengthened Merchant Ship
    DING Shifeng (丁仕风), ZHOU Li∗ (周 利), GU Yingjie (顾颖杰), ZHOU Yajun (周亚军)
    2022, 27 (3):  298-306.  doi: 10.1007/s12204-022-2442-5
    Abstract ( 280 )   PDF (5084KB) ( 69 )  
    Merchant ships, which are quite different from icebreakers, usually require the light ice-strengthened bow under the floe-ice condition. According to ice-class B, requirements of China Classification Society (CCS), intermediate frames and thick hull plates are necessary for the ice belt area to resist floe-ice impact. However, due to the limited space, it is not practical to set so many intermediate longitudinals from manufacture point of view. In this paper, a modification method is proposed to solve the problem by maintaining the frame spacing and increasing the plate thickness. The aim is to make sure that the bow owns the equivalent ice-bearing capacity with the original frame spacing. At first, a bulk carrier with ice-class B is used for case study. According to the requirements of the ice class rule, a designed ice thickness is used to calculate the ice load acting on the bow area due to the impact of ice floe. Two structural models are presented to perform the strength analysis under ice load, including the out-shell plate model and the longitudinal model. The results show that increasing the plate thickness is helpful to remove the negative effect induced by enlarging the spacing of the longitudinal. A reasonable curve is presented to modify the bow for the ice-strengthened merchant ship, which shows the relationship between the increase of plate thickness and the spacing of longitudinal. Moreover, a model test of floe-ice–ship interaction is conducted to measure the dynamic ice load, based on which nonlinear dynamic FE analysis is used to verify the presented plate-thickness–longitudinal spacing curve. The results show that the proposed method can be used to improve the ice-strengthened bow structure effectively, which provides theoretical foundation to modify the requirement of CCS’s ice class rule.
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    Experimental Study on Hydrodynamic Response of Semisubmersible Platform-Based Bottom-Hinged Flap Wave Energy Converter
    LIN Yana∗ (林 焰), PEI Feib (裴 斐)
    2022, 27 (3):  307-315.  doi: 10.1007/s12204-022-2443-4
    Abstract ( 210 )   PDF (1368KB) ( 51 )  
    A semisubmersible platform-based (SPB) bottom-hinged flap (BHF) wave energy converter (WEC) concept is presented in this paper, and its platform hydrodynamic response was studied experimentally. Aimed at studying the special WEC-mounted platform response problem, both regular and irregular wave experiments were conducted. The frequency domain results of regular wave experiments are described in the form of response amplitude operators. The time domain results of irregular wave experiments are treated by statistical analysis and fast Fourier transformation. Regular wave experiments and irregular wave experiments show good consistency. The mooring system strongly affects the whole system, which is a considerable factor for WEC design. The influences of BHF mounted on the platform are revealed in both statistic and frequency spectral ways. The results of experiments give a guide for SPB design aiming to support BHF-WEC.
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    Hydrodynamic Performance of Air-Filled Wave Attenuator for Wave Control: Experimental Study
    PEREIRA Eric Joseph1 (佩雷拉·埃里克·约瑟夫), TEH Hee-Min1,2∗ (郑希铭), MA Zhe3 (马 哲)
    2022, 27 (3):  316-325.  doi: 10.1007/s12204-022-2444-3
    Abstract ( 214 )   PDF (901KB) ( 46 )  
    Numerous types of floating breakwaters have been proposed, tested and commercialized in the past decades. The majority of these breakwaters are made of solid bodies; hence, they are relatively bulky and are not readily to be rapidly installed at the targeted sites when immediate wave protection of the coastal and offshore facilities is needed. Furthermore, the application of these hard floating structures at the recreational beaches is rather unlikely due to potential deadly marine traffic collision. To overcome these problems, a flexible air-filled wave attenuator (AFWA) has been developed in the present study. This floating breakwater is made of flexible waterproof membrane materials. The main body consists of a rectangular air-filled prism and is ballasted by sandbags located around the floating module. The objective of this study is to evaluate the wave transmission, wave reflection, energy dissipation, motion responses and mooring forces of the AFWA under the random wave actions using physical modelling. The test model located in a 20 m long wave flume was subjected to a range of wave heights and periods. The wave profiles in the vicinity of the test model were measured using wave probes for determination of wave transmission, reflection and energy loss coefficients. The motion responses in terms of heave, surge and pitch, and wave forces acting on the mooring lines were measured using a motion tracking system and load cells, respectively. The experimental results reveal that the AFWA is effective in attenuating up to 95% in the incoming wave height and has low-wave-reflection properties, which is commendable for floating breakwaters.
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    Design and Overall Strength Analysis of Multi-Functional Elastic Connections Floating Breakwater System
    HUO Fali∗ (霍发力), YANG Hongkun (杨宏坤), GUO Jianting (郭建廷), JI Chunyan (嵇春艳), NIU Jianjie (牛建杰), WANG Ke (王 珂)
    2022, 27 (3):  326-338.  doi: 10.1007/s12204-022-2413-x
    Abstract ( 256 )   PDF (3201KB) ( 39 )  
    As a new type of marine structure, floating breakwater can provide suitable water area for coastal residents. In this paper, a multi-module floating breakwater with three cylinders was designed. According to the characteristics of each module, the elastic connector was created. The cabins with functions such as living, generating electricity and entertainment were arranged. A linear spring constrained design wave (LSCDW) method for strength analysis of floating marine structures with multi-module elastic connections was proposed. The numerical model was verified by 1 : 50 similarity ratio in the test tank. According to the analysis of design wave and extreme wave conditions, considering the mooring loads and environmental loads and connector loads, the overall strength of breakwater was analyzed by LSCDW method. These studies can provide new insights and theoretical guidance for the design of multi-module floating structures.
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    Dynamic Stability Analysis of Backhoe Dredger Based on Time Domain Method
    CHEN Yihua1 (陈熠画), CHEN Xinquan1∗ (陈新权), YANG Qi1,2 (杨 启), OUYANG Yiping1 (欧阳义平)
    2022, 27 (3):  339-345.  doi: 10.1007/s12204-021-2272-x
    Abstract ( 270 )   PDF (1221KB) ( 33 )  
    When incidents happen with the positioning spud of a backhoe dredger, the hull loses stability, heels significantly, and may even capsize under extreme conditions. Coupling the hydrodynamics and spud vibrations, this paper investigates the dynamic stability of a backhoe dredger after spud failure based on the time domain method. The maximum dynamic heeling angle verifies the stability of the backhoe dredger. To identify the influences of environmental load, operating conditions, and spud-soil interactions, numerical motion simulations were conducted in the time domain. The main conclusions on dynamic stability consider the influences of relative environmental and operational factors. This study provides a powerful and efficient approach to analyze the dynamic stability of backhoe dredgers and to design flooding angles.
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    Multiobjective Optimization of Hull Form Based on Global Optimization Algorithm
    LIU Jiea (刘 洁), ZHANG Baojib∗ (张宝吉)
    2022, 27 (3):  346-355.  doi: 10.1007/s12204-022-2445-2
    Abstract ( 185 )   PDF (942KB) ( 47 )  
    Rankine source method, optimization technology, parametric modeling technology, and improved mul tiobjective optimization algorithm were combined to investigate the multiobjective optimization design of hull form. A multiobjective and multilevel optimization design framework was constructed for the comprehensive navigation performance of ships. CAESES software was utilized as the optimization platform, and nondominated sorting genetic algorithm II (NSGA-II) was used to conduct multiobjective optimization research on the resis tance and sea-keeping performance of the ITTC Ship A-2 fishing vessel. Optimization objectives of this study are heave/pitch response amplitude and wave-making resistance. Taking the displacement and the length between perpendiculars as constraints, we optimized the profile of the hull. Analytic hierarchy process (AHP) and tech nique for order preference by similarity to ideal solution (TOPSIS) were used to sort and select Pareto solutions and determine weight coefficient of each navigation performance objective in the general objective. Finally, the hydrodynamic performance before and after the parametric deformation of the hull was compared. The results show that both the wave-making resistance and heave/pitch amplitude of the optimized hull form are reduced, and the satisfactory optimal hull form is obtained. The results of this study have a certain reference value for the initial stage of multiobjective optimization design of hull form.
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    Numerical Simulation of the Flow in a Waterjet Intake Under Different Motion Conditions
    XU Huilia (许慧丽), ZOU Zaojiana,b∗ (邹早建)
    2022, 27 (3):  356-364.  doi: 10.1007/s12204-021-2321-5
    Abstract ( 176 )   PDF (2634KB) ( 38 )  
    By solving the three-dimensional incompressible Reynolds-averaged Navier-Stokes equations, numerical simulations of the viscous flow within a flush type intake duct of a waterjet under different motion conditions are carried out. Therein, the effects of the steering and reversing unit as well as the impeller shaft on the flow field are taken into account. The numerical results show that the static pressure under backward conditions with the reversing jet flow is the lowest, and the cavitations are most likely to occur within the intake duct. The flow field under forward conditions is less uniform because of the shaft, while the velocity uniformity under backward conditions is improved. The shaft rotation causes an asymmetric secondary flow above the shaft under all conditions. The pressure contours under backward conditions with the reversing jet flow are sensitive to the presence of the shaft. This study can provide some references for the design optimization of waterjet propulsion system.
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    Experimental Investigation and Numerical Simulation of Ship Stern Structural Vibration Model
    YE Xinghong (叶星宏), XIA Lijuan∗ (夏利娟)
    2022, 27 (3):  365-374.  doi: 10.1007/s12204-020-2248-2
    Abstract ( 160 )   PDF (3328KB) ( 39 )  
    Vibration at the stern area is generally the most severe of the entire ship hull, which has always at tracted special attention by ship designers and researchers. With reference to a real ship structural layout, a scaled stern model of steel structure was innovatively designed to carry out the mode and response tests. Corresponding finite element (FE) model representing the tested structure was established for verification of commonly-used calculation methods of modal parameters and response. Good agreement between experimental and numerical results demonstrates the credibility of FE method, and some key points of modeling and calculating are discussed. In addition, with the combination of the experiment and calculation, some vibration characteristics of ship stern structure are summarized for future ship design guideline.
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    Two-Stage Scheme for Disturbance Rejection Hovering Control of Underwater Vehicles
    BI Anyuana (毕安元), FENG Zhengpinga,b∗ (冯正平), ZHU Yuchena (朱昱琛), DENG Xua (邓 旭)
    2022, 27 (3):  375-382.  doi: 10.1007/s12204-021-2341-1
    Abstract ( 252 )   PDF (1043KB) ( 43 )  
    A two-stage model-independent hovering control scheme for underwater vehicles, which are subject to unknown yet constant external disturbance, to eliminate steady-state depth error is proposed. Proportional derivative (PD) state feedback control law is adopted as the ballast mass planner at the first stage for the vehicle to reach both hydrostatic balance and a steady depth. The residual depth error is then removed by an additional disturbance rejection control at the second stage. Global asymptotic stability of the whole system is guaranteed via Lyapunov approach. The effectiveness of the proposed scheme is illustrated by the simulation of diving control of an underwater vehicle with hydraulic variable ballast system.
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    Switched Three-Dimensional Decoupling Stabilization of Underactuated Autonomous Underwater Vehicles
    FANG Haolin (房浩霖), ZHANG Jiawen (张家闻), LI Jiawang∗ (李家旺)
    2022, 27 (3):  383-392.  doi: 10.1007/s12204-022-2446-1
    Abstract ( 286 )   PDF (897KB) ( 33 )  
    A three-dimensional stabilization problem for underactuated autonomous underwater vehicles (AUVs) is addressed in this paper. A novel coordinate transformation form consisting of state modifications and input transformations is introduced such that the whole system is divided into two decoupled one-order subsystems. Some switching functions are presented to further decouple the underactuated dynamics and to produce persis tently exciting (PE) signals for those underactuated states. Based on the aforementioned results, a quite simple control law is designed to achieve global three-dimensional asymptotic convergence of all states of underactuated AUVs. Comparative simulations are carried out to validate the effectiveness and performance of the proposed control scheme.
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    Improved Nonsingular Fast Terminal Sliding Mode Control of Unmanned Underwater Hovering Vehicle
    HE Chenlua (何晨璐), FENG Zhengpinga,b∗ (冯正平)
    2022, 27 (3):  393-401.  doi: 10.1007/s12204-022-2447-0
    Abstract ( 260 )   PDF (1034KB) ( 49 )  
    An improved nonsingular fast terminal sliding mode manifold based on scaled state error is proposed in this paper. It can significantly accelerate the convergence rate of the state error which is initially far from the origin and achieve the fixed-time convergence. In addition, conventional double power term based reaching law is improved to ensure the convergence of sliding state in the presence of disturbances. The proposed approach is applied to the hovering control of an unmanned underwater vehicle. The controller exhibits both fast convergence and strong robustness to model uncertainty and external disturbances
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    Submarine Multi-Model Switching Control Under Full Working Condition Based on Machine Learning
    LIANG Liang1 (梁 良), SHI Ying1∗ (石 英), MOU Junmin2∗ (牟军敏)
    2022, 27 (3):  402-410.  doi: 10.1007/s12204-021-2284-6
    Abstract ( 181 )   PDF (629KB) ( 39 )  
    A continuous submarine depth control strategy based on multi-model and machine learning switching method under full working condition is proposed in this paper. A submarine motion model with six-degree-of freedom is first built and decoupled according to the force analysis. The control set with corresponding precise model set is then optimized according to different working conditions. The multi-model switching strategy is studied using machine learning algorithm. The simulation experiments indicate that a multi-model controller comprised of the proportional-integral-derivative (PID), fuzzy PID (FPID) and model predictive controllers with support vector machine (SVM) switching strategy can realize the continuous submarine depth control under full working condition, showing a good control performance compared with a single PID controller.
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    Machine Learning-Based Approach to Liner Shipping Schedule Design
    DU Jian1∗ (杜 剑), ZHAO Xu2 (赵 旭), GUO Liming2 (郭力铭), WANG Jun2 (王 军)
    2022, 27 (3):  411-423.  doi: 10.1007/s12204-021-2338-9
    Abstract ( 240 )   PDF (524KB) ( 44 )  
    This paper studied a tactical liner shipping schedule design issue under sail and port time uncertainties, which is the determination of the planned arrival time at each port call as well as the punctuality rate and number of assigned ship on the route. A number of studies have tried to introduce the operational speed adjustment measure into this tactical schedule design issue, to alleviate the discrepancies between designed schedule and maritime practice. On the one hand, weather conditions can lead to speed loss phenomenon of ships, which may result in the failure of ships’ punctual arrivals. On the other hand, improving the ability of speed adjustment can decrease the late-arrival compensation, but increase the fuel consumption cost. Then, we formulated a machine learning-based liner shipping schedule design model aiming at above-mentioned two limitations on speed adjustment measure. And a machine learning-based approach has been designed, where the speed adjustment simulation, the neural network training and the reinforcement learning were included. Numerical experiments were conducted to validate our results and derive managerial insights, and then the applicability of machine learning method in shipping optimization issue has been confirmed.
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    Shipping Economics Development: A Review from the Perspective of the Shipping Industry Chain for the Past Four Decades
    XIA Qiliang (夏启亮), CHEN Feier ∗ (陈飞儿)
    2022, 27 (3):  424-436.  doi: 10.1007/s12204-022-2449-y
    Abstract ( 174 )   PDF (622KB) ( 61 )  
    To know the development of shipping economics, it is meaningful to overview shipping economics systemically from the perspective of markets and the shipping industry chain. To stimulate future research, this article presents an introduction to the evolution of research models including static models, dynamic models and networks theory, the characteristics of shipping markets including volatility, seasonal and market cycle, and a comprehensive review of the development of shipping economics in the past four decades. We review shipping economics in the following steps: single market’s research is generalized including the freight market, financial market including FFA market and investment market, shipbuilding market, and secondhand market; two markets’ correlation, information transmission, spillover effects, and other rules in shipping markets are surveyed; the correlation and risk of multi-markets are also investigated. Then, we summarize relationships of the shipping industry chain. Finally, we figure out issues in this field that need further study.
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