Journal of Marine Science and Engineering

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14 pages, 3002 KiB

Open AccessArticle

Uncertainty Analysis and Maneuver Simulation of Standard Ship Model

by Hui Li, Nan Zhao, Jian Zhou, Xiangyu Chen and Chenxu Wang

J. Mar. Sci. Eng. 2024, 12(7), 1230; https://doi.org/10.3390/jmse12071230 - 21 Jul 2024

Viewed by 913

Abstract

Maneuver simulation of a standard ship model gives indication of numerical accuracy. In the numerical calculation of ship maneuvering, uncertainty analysis is a necessary step to ensure the accuracy of the calculation. In this study, uncertainty pair analysis is carried out in the [...] Read more.

Maneuver simulation of a standard ship model gives indication of numerical accuracy. In the numerical calculation of ship maneuvering, uncertainty analysis is a necessary step to ensure the accuracy of the calculation. In this study, uncertainty pair analysis is carried out in the simulation of the turning circle motion of the standard ship model ONRT in waves. According to the uncertainty analysis procedure recommended by the International Towing Tank Conference (ITTC), the change of ship resistance caused by the number of grids is studied to determine the influence of grid density on the numerical prediction. The simulation of turning motion in waves is carried out based on the uncertainty analysis. It is found that the minimum number of overset grids for this simulation is 1.4 million. The numerical results are fairly accurate compared to experimental results, and this technique provides a method with low calculated cost for this simulation. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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13 pages, 2804 KiB

Open AccessArticle

MTP-YOLO: You Only Look Once Based Maritime Tiny Person Detector for Emergency Rescue

by Yonggang Shi, Shaokun Li, Ziyan Liu, Zhiguo Zhou and Xuehua Zhou

J. Mar. Sci. Eng. 2024, 12(4), 669; https://doi.org/10.3390/jmse12040669 - 18 Apr 2024

Cited by 6 | Viewed by 2373

Abstract

Tiny person detection based on computer vision technology is critical for maritime emergency rescue. However, humans appear very small on the vast sea surface, and this poses a huge challenge in identifying them. In this study, a single-stage tiny person detector, namely the [...] Read more.

Tiny person detection based on computer vision technology is critical for maritime emergency rescue. However, humans appear very small on the vast sea surface, and this poses a huge challenge in identifying them. In this study, a single-stage tiny person detector, namely the “You only look once”-based Maritime Tiny Person detector (MTP-YOLO), is proposed for detecting maritime tiny persons. Specifically, we designed the cross-stage partial layer with two convolutions Efficient Layer Aggregation Networks (C2fELAN) by drawing on the Generalized Efficient Layer Aggregation Networks (GELAN) of the latest YOLOv9, which preserves the key features of a tiny person during the calculations. Meanwhile, in order to accurately detect tiny persons in complex backgrounds, we adopted a Multi-level Cascaded Enhanced Convolutional Block Attention Module (MCE-CBAM) to make the network attach importance to the area where the object is located. Finally, by analyzing the sensitivity of tiny objects to position and scale deviation, we proposed a new object position regression cost function called Weighted Efficient Intersection over Union (W-EIoU) Loss. We verified our proposed MTP-YOLO on the TinyPersonv2 dataset. All these results confirm that this method significantly improves model performance while maintaining a low number of parameters and can therefore be applied to maritime emergency rescue missions. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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17 pages, 3182 KiB

Open AccessArticle

Machine Learning-Based Approach to Identifying Fall Risk in Seafarers Using Wearable Sensors

by Jungyeon Choi, Brian A. Knarr, Jong-Hoon Youn and Kwang Yoon Song

J. Mar. Sci. Eng. 2024, 12(2), 356; https://doi.org/10.3390/jmse12020356 - 19 Feb 2024

Viewed by 1726

Abstract

Falls on a ship cause severe injuries, and an accident falling off board, referred to as “man overboard” (MOB), can lead to death. Thus, it is crucial to accurately and timely detect the risk of falling. Wearable sensors, unlike camera and radar sensors, [...] Read more.

Falls on a ship cause severe injuries, and an accident falling off board, referred to as “man overboard” (MOB), can lead to death. Thus, it is crucial to accurately and timely detect the risk of falling. Wearable sensors, unlike camera and radar sensors, are affordable and easily accessible regardless of the weather conditions. This study aimed to identify the fall risk level (i.e., high and low risk) among individuals on board using wearable sensors. We collected walking data from accelerometers during the experiment by simulating the ship’s rolling motions using a computer-assisted rehabilitation environment (CAREN). With the best features selected by LASSO, eight machine learning (ML) models were implemented with a synthetic minority oversampling technique (SMOTE) and the best-tuned hyperparameters. In all ML models, the performance in classifying fall risk showed overall a good accuracy (0.7778 to 0.8519), sensitivity (0.7556 to 0.8667), specificity (0.7778 to 0.8889), and AUC (0.7673 to 0.9204). Logistic regression showed the best performance in terms of the AUC for both training (0.9483) and testing (0.9204). We anticipate that this study will effectively help identify the risk of falls on ships and aid in developing a monitoring system capable of averting falls and detecting MOB situations. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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22 pages, 3460 KiB

Open AccessArticle

YOLOv7-Ship: A Lightweight Algorithm for Ship Object Detection in Complex Marine Environments

by Zhikai Jiang, Li Su and Yuxin Sun

J. Mar. Sci. Eng. 2024, 12(1), 190; https://doi.org/10.3390/jmse12010190 - 20 Jan 2024

Cited by 6 | Viewed by 2274

Abstract

Accurate ship object detection ensures navigation safety and effective maritime traffic management. Existing ship target detection models often have the problem of missed detection in complex marine environments, and it is hard to achieve high accuracy and real-time performance simultaneously. To address these [...] Read more.

Accurate ship object detection ensures navigation safety and effective maritime traffic management. Existing ship target detection models often have the problem of missed detection in complex marine environments, and it is hard to achieve high accuracy and real-time performance simultaneously. To address these issues, this paper proposes a lightweight ship object detection model called YOLOv7-Ship to perform end-to-end ship detection in complex marine environments. At first, we insert the improved “coordinate attention mechanism” (CA-M) in the backbone of the YOLOv7-Tiny model at the appropriate location. Then, the feature extraction capability of the convolution module is enhanced by embedding omnidimensional dynamic convolution (ODconv) into the efficient layer aggregation network (ELAN). Furthermore, content-aware feature reorganization (CARAFE) and SIoU are introduced into the model to improve its convergence speed and detection precision for small targets. Finally, to handle the scarcity of ship data in complex marine environments, we build the ship dataset, which contains 5100 real ship images. Experimental results show that, compared with the baseline YOLOv7-Tiny model, YOLOv7-Ship improves the mean average precision (mAP) by 2.2% on the self-built dataset. The model also has a lightweight feature with a detection speed of 75 frames per second, which can meet the need for real-time detection in complex marine environments to a certain extent, highlighting its advantages for the safety of maritime navigation. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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21 pages, 5371 KiB

Open AccessArticle

A High-Precision Detection Model of Small Objects in Maritime UAV Perspective Based on Improved YOLOv5

by Zhilin Yang, Yong Yin, Qianfeng Jing and Zeyuan Shao

J. Mar. Sci. Eng. 2023, 11(9), 1680; https://doi.org/10.3390/jmse11091680 - 25 Aug 2023

Cited by 5 | Viewed by 1893

Abstract

Object detection by shipborne unmanned aerial vehicles (UAVs) equipped with electro-optical (EO) sensors plays an important role in maritime rescue and ocean monitoring. However, high-precision and low-latency maritime environment small-object-detection algorithms remain a major challenge. To address this problem, this paper proposes the [...] Read more.

Object detection by shipborne unmanned aerial vehicles (UAVs) equipped with electro-optical (EO) sensors plays an important role in maritime rescue and ocean monitoring. However, high-precision and low-latency maritime environment small-object-detection algorithms remain a major challenge. To address this problem, this paper proposes the YOLO-BEV (“you only look once”–“bird’s-eye view”) model. First, we constructed a bidirectional feature fusion module—that is, PAN+ (Path Aggregation Network+)—adding an extremely-small-object-prediction head to deal with the large-scale variance of targets at different heights. Second, we propose a C2fSESA (Squeeze-and-Excitation Spatial Attention Based on C2f) module based on the attention mechanism to obtain richer feature information by aggregating features of different depth layers. Finally, we describe a lightweight spatial pyramid pooling structure called RGSPP (Random and Group Convolution Spatial Pyramid Pooling), which uses group convolution and random channel rearrangement to reduce the model’s computational overhead and improve its generalization ability. The article compares the YOLO-BEV model with other object-detection algorithms on the publicly available MOBDrone dataset. The research results show that the mAP_0.5 value of YOLO-BEV reached 97.1%, which is 4.3% higher than that of YOLOv5, and the average precision for small objects increased by 22.2%. Additionally, the YOLO-BEV model maintained a detection speed of 48 frames per second (FPS). Consequently, the proposed method effectively balances the accuracy and efficiency of object-detection in shipborne UAV scenarios, outperforming other related techniques in shipboard UAV maritime object detection. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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16 pages, 6723 KiB

Open AccessArticle

Enhancement of Cruise Boat Resilience to Strong Convective Gusts with Global Model Cumulus Variable Prediction

by Jun Jian, Jinhai Chen and Peter J. Webster

J. Mar. Sci. Eng. 2023, 11(8), 1588; https://doi.org/10.3390/jmse11081588 - 13 Aug 2023

Viewed by 1615

Abstract

Ship pilots and maritime safety administration have an urgent need for more accurate and earlier warnings for strong wind gusts. This study firstly investigated the “Oriental Star” cruise ship capsizing event in 2015, one of the deadliest shipwreck events in recent years, and [...] Read more.

Ship pilots and maritime safety administration have an urgent need for more accurate and earlier warnings for strong wind gusts. This study firstly investigated the “Oriental Star” cruise ship capsizing event in 2015, one of the deadliest shipwreck events in recent years, and explored all related hydro-meteorological components in a global mesoscale model. It was found that rather than the missing signal in raw surface-wind prediction, the cumulus precipitation variable (CP) increased dramatically during the accident occurrence, which significantly corresponds to a sub-grid strong wind gust. The effective lead time could be extended from 24 h (deterministic model) to 48 h (ensemble model). This finding was then verified in another two recent deadly cruise boat accidents. The introduction of the new variable aims to improve the current maritime safeguard system in predicting sub-grid strong wind gusts for small-sized cruise boats offshore and in inland rivers. Finally, an automatic response system was developed to provide economical convection prediction via INMARSAT email communication, aiming to explore operational severe convective gust early warning and appropriate numerical mesoscale model applications. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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20 pages, 10565 KiB

Open AccessArticle

Research on Construction and Application of Ocean Circulation Spatial–Temporal Ontology

by Hao Zhang, Anmin Zhang, Chenxu Wang, Liuyang Zhang and Shuai Liu

J. Mar. Sci. Eng. 2023, 11(6), 1252; https://doi.org/10.3390/jmse11061252 - 20 Jun 2023

Viewed by 1632

Abstract

Due to the absence of a comprehensive knowledge system for modeling ocean circulation, there is ambiguity and diversity in the semantic expression of ocean circulation. This makes it difficult to organize and share relevant spatiotemporal data effectively. This paper addresses the issue of [...] Read more.

Due to the absence of a comprehensive knowledge system for modeling ocean circulation, there is ambiguity and diversity in the semantic expression of ocean circulation. This makes it difficult to organize and share relevant spatiotemporal data effectively. This paper addresses the issue of ocean circulation by introducing ontological theory and methodology based on a comprehensive analysis of domain knowledge. Through a comprehensive analysis of the conceptual and relational characteristics of different elements, we define classes, properties, spatiotemporal relationships, and inference conditions with which to formally express concepts and relationships in ocean circulation, and finally complete the construction of ocean circulation ontology. The formal expression of the Equatorial Counter Current is presented as an example with which to validate the effectiveness of ontological construction. Additionally, an ontology-based knowledge base of ocean circulation is proposed. The construction framework is described, and several examples of knowledge base queries are also illustrated. The results demonstrate that this ontology can effectively represent the relevant knowledge within ocean circulation and provide a meaningful reference for investigating knowledge sharing and semantic integration within this field. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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21 pages, 6234 KiB

Open AccessArticle

Ship Intrusion Collision Risk Model Based on a Dynamic Elliptical Domain

by Weifeng Li, Lufeng Zhong, Yaochen Liu and Guoyou Shi

J. Mar. Sci. Eng. 2023, 11(6), 1122; https://doi.org/10.3390/jmse11061122 - 26 May 2023

Cited by 4 | Viewed by 1746

Abstract

To improve navigation safety in maritime environments, a key step is to reduce the influence of human factors on the risk assessment of ship collisions by automating the decision-making process as much as possible. This paper optimizes a dynamic elliptical ship domain based [...] Read more.

To improve navigation safety in maritime environments, a key step is to reduce the influence of human factors on the risk assessment of ship collisions by automating the decision-making process as much as possible. This paper optimizes a dynamic elliptical ship domain based on Automatic Identification System (AIS) data, combines the relative motion between ships in different encounter situations and the level of ship intrusion in the domain, and proposes a ship intrusion collision risk (SICR) model. The simulation results show that the optimized ship domain meets the visualization requirements, and the intrusion model has good collision risk perception ability, which can be used as the evaluation standard of ship collision risk: when the SICR is 0.5–0.6, the ship can establish a collaborative collision avoidance decision-making relationship with other ships, and the action ship can take effective collision avoidance action at the best time when the SICR is between 0.3 and 0.5. The SICR model can give navigators a more accurate and rapid perception of navigation risks, enabling timely maneuvering decisions, and improving navigation safety. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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16 pages, 1426 KiB

Open AccessArticle

A Study on a Novel Inverted Ultra-Short Baseline Positioning System and Phase Difference Estimation

by Shuai Liu, Haoran Guo, Zhiwen Qian, Jie Li, Xiaojian Wang, Wanzhong Sun, Lihua Zhang and Anmin Zhang

J. Mar. Sci. Eng. 2023, 11(5), 952; https://doi.org/10.3390/jmse11050952 - 29 Apr 2023

Cited by 4 | Viewed by 1585

Abstract

Autonomous underwater vehicles (AUVs) are important tools for exploring and studying the ocean. To improve the stealthiness of AUV positioning, a new type of inverted ultra-short baseline (i-USBL) positioning system is proposed in this paper. The system uses a surface GPS buoy as [...] Read more.

Autonomous underwater vehicles (AUVs) are important tools for exploring and studying the ocean. To improve the stealthiness of AUV positioning, a new type of inverted ultra-short baseline (i-USBL) positioning system is proposed in this paper. The system uses a surface GPS buoy as a positioning base station to transmit positioning signals to the AUV, which receives the signals through the i-USBL and calculates its own coordinates. In this way, the power consumption of the AUV will be lower, improving its endurance. In addition, azimuth observation is one of the key observation quantities in ultra-short baseline positioning systems. Therefore, this paper derives two phase difference estimation algorithms for azimuth measurement, which are the Least Mean Square (LMS) algorithm and the Discrete Fourier Transform (DFT) algorithm. Simulation results show that when the signal-to-noise ratio (SNR) is less than or equal to 0 dB, the DFT algorithm has higher accuracy; when SNR is greater than or equal to 10 dB, LMS has slightly higher accuracy than DFT; however, DFT is more stable than LMS at all SNRs. When SNR is 20 dB, the maximum azimuth measurement error of LMS and DFT is 0.3301° and 0.2204°, respectively, which can meet the positioning accuracy requirements. The average running times of LMS and DFT are 0.085 s and 0.011 s, respectively, and LMS has a faster running speed. In summary, the LMS algorithm can be used for azimuth observation when the SNR is good, and DFT can be applied when the SNR is poor. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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16 pages, 5205 KiB

Open AccessArticle

Cooperative Path Tracking for Swarm of MASSs Based on Consensus Theory

by Xuewei Li, Miao Gao, Zhen Kang, Xiangyu Chen, Xi Zeng, Shuai Chen, Haixin Sun and Anmin Zhang

J. Mar. Sci. Eng. 2023, 11(2), 312; https://doi.org/10.3390/jmse11020312 - 1 Feb 2023

Viewed by 1548

Abstract

At present, marine autonomous surface ships (MASSs) play a huge role in marine shipping, surveying and mapping, safeguarding the rights and interests of marine space, and other maritime tasks. The cooperative operation of a swarm of MASSs can extend the scope of operation [...] Read more.

At present, marine autonomous surface ships (MASSs) play a huge role in marine shipping, surveying and mapping, safeguarding the rights and interests of marine space, and other maritime tasks. The cooperative operation of a swarm of MASSs can extend the scope of operation of the MASSs, and thus allow them to carry out more complex tasks. Path tracking is an important problem for the control of a swarm of MASSs. In this paper, the control of underactuated MASSs is decoupled, to control the heading and speed, respectively. First of all, in the path tracking, the improved arc LOS guidance law is introduced, and the heading torque controller is designed, so that the MASS can track the reference path efficiently and accurately. Then the single-path guided path tracking without formation of the swarm of MASSs is studied, the reference path of the swarm center tracking is defined, and the heave thrust controller of the swarm of MASSs is designed based on consensus theory, so that the surge velocity of the MASS can tend towards consistentcy, and finally converge to the desired speed. Finally, the effectiveness of the proposed control strategy is verified by two groups of simulation experiments. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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13 pages, 4776 KiB

Open AccessArticle

Direct Underwater Sound Velocity Measurement Based on the Acousto-Optic Self-Interference Effect between the Chirp Signal and the Optical Frequency Comb

by Zihui Yang, Fanpeng Dong, Hongguang Liu, Xiaoxia Yang, Zhiwei Li and Bin Xue

J. Mar. Sci. Eng. 2023, 11(1), 18; https://doi.org/10.3390/jmse11010018 - 23 Dec 2022

Viewed by 2057

Abstract

Underwater sound speed plays a vital role in maritime safety. Based on the acousto-optic self-interference effect, we proposed a new method to measure underwater sound speed utilizing Raman–Nath diffraction, generated by the acousto-optic effect between an optical frequency comb and pulsed chirp signal. [...] Read more.

Underwater sound speed plays a vital role in maritime safety. Based on the acousto-optic self-interference effect, we proposed a new method to measure underwater sound speed utilizing Raman–Nath diffraction, generated by the acousto-optic effect between an optical frequency comb and pulsed chirp signal. When the pulsed chirp travels between the measurement and reference arm in the experimental setup that we constructed, the same signal resulting from acousto-optic self-interference is produced. The time gap between the two identical signals represents the time interval. Thus, we can determine the time-of-flight using cross-correlation. The optical path difference between the two arms is double the flight distance of ultrasonic waves and can easily be obtained using femtosecond laser interferometry. The time gap and the distance can be used to measure sound speed. The experimental results show that the chirp signal improves the signal-to-noise ratio and expands the applicable time-of-flight algorithm. The waveform pulse width after cross-correlation is 1.5 μs, compared with 40 μs before. The time-of-flight uncertainty can achieve 1.03 ns compared to 8.6 ns before. Uncertainty of sound velocity can achieve 0.026 m/s. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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16 pages, 3640 KiB

Open AccessArticle

Collision Risk Index Calculation Based on an Improved Ship Domain Model

by Weifeng Li, Lufeng Zhong, Yang Xu and Guoyou Shi

J. Mar. Sci. Eng. 2022, 10(12), 2016; https://doi.org/10.3390/jmse10122016 - 16 Dec 2022

Cited by 10 | Viewed by 4943

Abstract

The traditional ship collision risk index model based on the distance at the closest point of approach (DCPA) and the time to the closest point of approach (TCPA) is insufficient for estimating ship collision risk and planning collision avoidance operations. This paper constructs [...] Read more.

The traditional ship collision risk index model based on the distance at the closest point of approach (DCPA) and the time to the closest point of approach (TCPA) is insufficient for estimating ship collision risk and planning collision avoidance operations. This paper constructs an elliptical, dynamic ship domain that changes with ship speed and maneuverability parameters to overcome subjective human factors. Based on the constructed domain model, the concept of the ship domain proximity factor is introduced to improve the ship collision risk model based on DCPA and TCPA, and a risk calculation function model that considers the safety of ship navigation is constructed. The numerical calculation of the improved collision risk index calculation model confirms that the enhanced model has a higher rate of identification of risk between ships. The model is more compatible with the requirements of ship navigation decision-making and can provide theoretical support and a technical basis for research on ship collision avoidance decision-making. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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21 pages, 11388 KiB

Open AccessArticle

Formation of MASS Collision Avoidance and Path following Based on Artificial Potential Field in Constrained Environment

by Xiangyu Chen, Miao Gao, Zhen Kang, Jian Zhou, Shuai Chen, Zihao Liao, Haixin Sun and Anmin Zhang

J. Mar. Sci. Eng. 2022, 10(11), 1791; https://doi.org/10.3390/jmse10111791 - 21 Nov 2022

Cited by 6 | Viewed by 2093

Abstract

It is essential to promote the intelligence and autonomy of Maritime Autonomous Surface Ships (MASSs). This study proposed an automatic collision-avoidance method based on an improved Artificial Potential Field (APF) with the formation of MASSs (F-MASSs). Firstly, the navigation environment model was constructed [...] Read more.

It is essential to promote the intelligence and autonomy of Maritime Autonomous Surface Ships (MASSs). This study proposed an automatic collision-avoidance method based on an improved Artificial Potential Field (APF) with the formation of MASSs (F-MASSs). Firstly, the navigation environment model was constructed by the S-57 Electronic Navigation Chart (ENC) data in Tianjin Port. The Formation Ship State Parameter (FSSP) definition was proposed for the port environment under multiple constraints that considered the navigation conditions of the MASSs. The formation pattern transformation was settled by changing the formation ship state parameter. Considering the constraints of an ‘unmanned–manned’ encounter situation, the static obstacles, and the design of the channel area improved artificial potential method for the formation. Finally, the simulation experiment was carried out in the sea near Tianjin Port to verify the effectiveness of the algorithm under multiple constraints. The results indicate that the method can satisfy the integrated operation of collision avoidance and path following in a constrained environment, and it can support the application of merchant F-MASS autonomous navigation in the future. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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20 pages, 85581 KiB

Open AccessArticle

Multi-Scale Object Detection Model for Autonomous Ship Navigation in Maritime Environment

by Zeyuan Shao, Hongguang Lyu, Yong Yin, Tao Cheng, Xiaowei Gao, Wenjun Zhang, Qianfeng Jing, Yanjie Zhao and Lunping Zhang

J. Mar. Sci. Eng. 2022, 10(11), 1783; https://doi.org/10.3390/jmse10111783 - 19 Nov 2022

Cited by 20 | Viewed by 4562

Abstract

Accurate detection of sea-surface objects is vital for the safe navigation of autonomous ships. With the continuous development of artificial intelligence, electro-optical (EO) sensors such as video cameras are used to supplement marine radar to improve the detection of objects that produce weak [...] Read more.

Accurate detection of sea-surface objects is vital for the safe navigation of autonomous ships. With the continuous development of artificial intelligence, electro-optical (EO) sensors such as video cameras are used to supplement marine radar to improve the detection of objects that produce weak radar signals and small sizes. In this study, we propose an enhanced convolutional neural network (CNN) named VarifocalNet * that improves object detection in harsh maritime environments. Specifically, the feature representation and learning ability of the VarifocalNet model are improved by using a deformable convolution module, redesigning the loss function, introducing a soft non-maximum suppression algorithm, and incorporating multi-scale prediction methods. These strategies improve the accuracy and reliability of our CNN-based detection results under complex sea conditions, such as in turbulent waves, sea fog, and water reflection. Experimental results under different maritime conditions show that our method significantly outperforms similar methods (such as SSD, YOLOv3, RetinaNet, Faster R-CNN, Cascade R-CNN) in terms of the detection accuracy and robustness for small objects. The maritime obstacle detection results were obtained under harsh imaging conditions to demonstrate the performance of our network model. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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10 pages, 2036 KiB

Open AccessCommunication

Research on the Delimitation of Marine Spatial Pattern Based on the Goal of “Carbon Peaking and Carbon Neutrality”

by Qiwei Zhao, Xin Teng, Panpan Zhang, Wanchao Kang, Xue Meng and Shuang Wang

J. Mar. Sci. Eng. 2022, 10(10), 1566; https://doi.org/10.3390/jmse10101566 - 21 Oct 2022

Cited by 3 | Viewed by 1781

Abstract

In the context of carbon peaking and carbon neutrality (“double carbon”), it is urgent to clarify the effect of marine spatial planning (MSP) on carbon sink increases and emission reductions, since such planning acts as a spatial governance tool for the earth’s largest [...] Read more.

In the context of carbon peaking and carbon neutrality (“double carbon”), it is urgent to clarify the effect of marine spatial planning (MSP) on carbon sink increases and emission reductions, since such planning acts as a spatial governance tool for the earth’s largest carbon pool. In this paper, a linkage model between marine spatial functional zones and carbon distribution is established. To explore the relationship between marine spatial functional zones and carbon, the study analyzed the carbon increase or reduction role of sea-use activities in each zone and considered the carbon sequestration function of the marine ecosystem itself. A marine spatial pattern of “Two Spaces and Four Carbon Areas” is proposed to present the linkage. A carbon distribution pattern in marine space is delimited using the linkage model and the current MSP in the case study of the city of Tangshan, Hebei, China. Some measures have been taken or planned to be taken in Tangshan to improve the carbon sink function of the ecosystem and the marine space. The supporting role of MSP in achieving the “double carbon” goal is studied, and the paths and suggestions for integrating the “double carbon” goal into MSP are explored. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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21 pages, 8061 KiB

Open AccessArticle

Multi-Ship Encounter Situation Identification and Analysis Based on AIS Data and Graph Complex Network Theory

by Jixiang Zhu, Miao Gao, Anmin Zhang, Yingjun Hu and Xi Zeng

J. Mar. Sci. Eng. 2022, 10(10), 1536; https://doi.org/10.3390/jmse10101536 - 19 Oct 2022

Cited by 9 | Viewed by 2682

Abstract

In order to detect multi-ship encounter situations and improve the safety of navigation, this paper proposed a model which was able to mine multi-ship encounter situations from Automatic identification system (AIS) data and analyze the encounter spatial-temporal process and make collision avoidance decisions. [...] Read more.

In order to detect multi-ship encounter situations and improve the safety of navigation, this paper proposed a model which was able to mine multi-ship encounter situations from Automatic identification system (AIS) data and analyze the encounter spatial-temporal process and make collision avoidance decisions. Pairwise encounters identification results and ship motion index were combined into a ship encounter graph network which can use the complex network theory to describe the encounter spatial-temporal process. Network average degree, network average distance and network average clustering coefficient were selected. Based on the recognition results of pairwise encounter identification results, a discrete multi-ship encounter network is constructed. The process of multi-ship encounters from simple to complex to simple is mined based on the process of average network degree from 0 to 0 to obtain a continuous spatial-temporal process. The results can be used for multi-ship encounter situation awareness, multi-ship collision avoidance decision-making and channel navigation evaluation, and also provide data for machine learning. Quaternary dynamic ship domain, fuzzy logic and the weighted PageRank algorithm were used to rank the whole network risk, which is critical to “key ship collision avoidance.” This method overcame the problem that the traditional collision risk evaluation method is only applicable to the difference between two ships and ship perception. The risk rank combined with the artificial potential field method was used. Compared with the traditional artificial potential field method, this method has fewer turns and a smoother trajectory. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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17 pages, 1256 KiB

Open AccessArticle

GNSS Real–Time Precise Point Positioning in Arctic Northeast Passage

by Mingwei Di, Bofeng Guo, Jie Ren, Xiang Wu, Zhaoyi Zhang, Yicheng Liu, Qingju Liu and Anmin Zhang

J. Mar. Sci. Eng. 2022, 10(10), 1345; https://doi.org/10.3390/jmse10101345 - 21 Sep 2022

Cited by 6 | Viewed by 2369

Abstract

Human activities in the Arctic regions have been increasing in recent years due to the impacts of climate change, such as Arctic Sea ice decline. For example, there has been an increase in Arctic shipping routes. A robust navigation system with a high [...] Read more.

Human activities in the Arctic regions have been increasing in recent years due to the impacts of climate change, such as Arctic Sea ice decline. For example, there has been an increase in Arctic shipping routes. A robust navigation system with a high positioning accuracy is required when traversing the extremely challenging Arctic environment to ensure the safety of human activities. However, the high–precision GNSS navigation and the positioning method, e.g., real–time kinematic (RTK), is not available in the polar regions due to the accessibility issues of the required infrastructures. On the other hand, the International GNSS Service (IGS) enables real–time applications; additionally, quick and convenient satellite communication systems are also available. This offers the possibility of real–time precise point positioning (RT–PPP) with multi–GNSS for high-precision navigation in the Arctic. In our paper, we analyzed the performance of multi–GNSS RT–PPP in the Arctic Northeast Passage (NEP), highlighting the following contributions: First, a GNSS device is installed on the M/V TIANHUI, which passed through the NEP from 10 September to 20 September 2019; Second, we quantitatively evaluated the collected GNSS signals in terms of the maximum satellite elevations, number of visible satellites (NSAT), position dilution of precision (PDOP) values, signal–to–noise ratio (SNR), and multipath errors. Third, we evaluated the accuracy of the CLK93 real–time products compared with the Deutsches GeoForschungsZentrum (GFZ) final products GBM. Finally, we carried out experiments for both single– (SF) and dual–frequency (DF) RT–PPP in the NEP during the 11–day testing period. Our experimental results show that meter–level positioning accuracy can be achieved with SF RT–PPP, while the DF RT–PPP model reaches sub–decimeter values and even centimeter–level accuracy. In addition, using the multi–GNSS method, we showed that the average RMS values of DF RT–PPP in the horizontal and vertical directions are 0.080 m and 0.057 m, respectively, demonstrating an improvement of approximately 70% over single–GPS solutions. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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Safety Improvements for High-Speed Planing Craft Occupants: A Systematic Review

by Fatemeh Roshan, Abbas Dashtimanesh and Pentti Kujala

J. Mar. Sci. Eng. 2024, 12(5), 845; https://doi.org/10.3390/jmse12050845 - 19 May 2024

Cited by 1 | Viewed by 1322

Abstract

Moving fast by high-speed planing craft (HSPC) is advantageous for some special missions, though it causes severe hull vibrations and shocks that can transfer to the human body and increase health and comfort risks. This study reviews the current safety standards to avoid [...] Read more.

Moving fast by high-speed planing craft (HSPC) is advantageous for some special missions, though it causes severe hull vibrations and shocks that can transfer to the human body and increase health and comfort risks. This study reviews the current safety standards to avoid human safety risks affected by whole-body vibrations (WBVs), as well as the safety status of HSPC occupants. In addition, the efficiency of motion-reduction devices (trim tab and interceptor) and shock/vibration-mitigation devices (shock-mitigation seat) in improving the safety of HSPC occupants is examined according to existing documents. The research methodology was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIS-MA) method, and published papers in the Scholar, Scopus, and Web of Science databases were analyzed. Because most of these publications are academic research, issues of bias in the eligible publications were not of particular interest. During this systematic review, many gaps and challenges in current information on safety improvement devices were found that need to be addressed in future studies, such as a lack of information on motion-reduction devices and shock-mitigation seat performance in reducing lateral and fore-and-aft motions. Referring to these gaps and challenges can be valuable as a suggestion to improve current knowledge in research and reduce safety risks. Full article

(This article belongs to the Special Issue Application of Advanced Technologies in Maritime Safety)

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