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Icebreaker assistance is a common but complex operation in ice-infested regions. Currently, the operational decision-making and the decisions regarding the safety indicators are primarily based on expert knowledge, resulting in subjectivity and the ad hoc nature of icebreaker assistance. This can negatively impact both the navigational efficiency o...
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... perspective during the same time duration are the potential targets, as the following navigation pattern naturally performs in such a way. Hausdorff distance is a shape-based distance metric that can be simply and effectively used in measuring the spatial distance of polygonal curves like trajectories (Besse, 2015;Kumar et al., 2020). As shown in Fig. 5, without the requirement of the same number of points for each trajectory, Hausdorff distance measures the minimum spatial distance from each point of the trajectory to all points of another trajectory based on Eqs 11-13 (L. Liu et al., ...
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... line in Fig. 14) differ within a small range, showing a high level of similarity. Compared to static and spatial features, dynamic features vary more. This is because, during the escort operation, the icebreaker would change the speed and course under the effect of ice, leading to the behavior changes of the assisted ship ( Zhang et al., 2018). Fig. 15 depicts these dynamic feature changes in detail. It is apparent that the speed and course of the icebreaker and the assisted ship performed quite similarly during the assistance operation. Behavior changes in the two ships happened subsequently. For example, as shown in the Course value in Fig. 10. Trajectories of icebreakers. Fig. 15, ...
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... al., 2018). Fig. 15 depicts these dynamic feature changes in detail. It is apparent that the speed and course of the icebreaker and the assisted ship performed quite similarly during the assistance operation. Behavior changes in the two ships happened subsequently. For example, as shown in the Course value in Fig. 10. Trajectories of icebreakers. Fig. 15, at around 3.1 h and 3.8 h, the course of the icebreaker changed, then the movement change was followed by the merchant ship, indicating an apparent coupled relationship between kinematic changes of the two ...
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... perspective during the same time duration are the potential targets, as the following navigation pattern naturally performs in such a way. Hausdorff distance is a shape-based distance metric that can be simply and effectively used in measuring the spatial distance of polygonal curves like trajectories (Besse, 2015;Kumar et al., 2020). As shown in Fig. 5, without the requirement of the same number of points for each trajectory, Hausdorff distance measures the minimum spatial distance from each point of the trajectory to all points of another trajectory based on Eqs 11-13 (L. Liu et al., ...
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... line in Fig. 14) differ within a small range, showing a high level of similarity. Compared to static and spatial features, dynamic features vary more. This is because, during the escort operation, the icebreaker would change the speed and course under the effect of ice, leading to the behavior changes of the assisted ship ( Zhang et al., 2018). Fig. 15 depicts these dynamic feature changes in detail. It is apparent that the speed and course of the icebreaker and the assisted ship performed quite similarly during the assistance operation. Behavior changes in the two ships happened subsequently. For example, as shown in the Course value in Fig. 10. Trajectories of icebreakers. Fig. 15, ...
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... al., 2018). Fig. 15 depicts these dynamic feature changes in detail. It is apparent that the speed and course of the icebreaker and the assisted ship performed quite similarly during the assistance operation. Behavior changes in the two ships happened subsequently. For example, as shown in the Course value in Fig. 10. Trajectories of icebreakers. Fig. 15, at around 3.1 h and 3.8 h, the course of the icebreaker changed, then the movement change was followed by the merchant ship, indicating an apparent coupled relationship between kinematic changes of the two ...
Citations
... However, this assistance introduces the risk of collision between the assisted ship and the icebreaker, posing dangers to both the crew and the ship (Liu et al., 2022a,b;Zhang et al., 2019b;Liu et al., 2022a,b). Therefore, there is an urgent need to develop a kinematic model for collaborative operations of intelligent ships in ice-covered waters, aiming to mitigate navigation risks during icebreaker assistance (Valdez Banda et al., 2015;Fan et al., 2020;Liu et al., 2022Liu et al., , 2022b. ...
... To investigate icebreaker operations, Goerlandt et al. (2017a) developed a procedure to visualize AIS data along with spatio-temporal information about sea ice and atmospheric conditions, and to identify and classify icebreaker operations based on this integrated dataset. Liu et al. (2022b) proposed a data mining method for the automatic identification and analysis of icebreaker assistance operations in ice-covered waters. This method can be used to identify icebreaker assistance operations. ...
This paper introduces a kinematic model for guiding intelligent ships under icebreaker assistance.
... This forms the technical foundation for collaborative ship control and intelligent dispatching, which is crucial for efficient maritime traffic management. The widespread implementation of AIS supports this goal by enhancing traffic data availability and accuracy (Zhang et al., 2021b;Liu et al., 2022). ...
Proactive traffic management is increasingly critical in maritime intelligent transportation systems. Central to this is maritime traffic forecasting, which leverages specific structures and properties of the problem. This study focuses on the traffic dynamics within convergent areas of inland waterways and proposes a method based on data mining followed by prediction using Automatic Identification System (AIS) data. This approach addresses uncertainties in ship voyage destinations and optimizes predictions for temporary stops in inland waterways. AIS data is processed to depict complete ship motion trajectories, grouping them into trajectory sets based on shared origin, destination, and route. These groups help represent maritime traffic patterns using the entrance and exit points of channels and the boundaries of the study area. Additionally, a stop detection model is applied to these trajectories to identify nodes within maritime traffic networks. A decision tree algorithm is then employed to train a classifier for predicting traffic patterns. The method was validated in the convergent area of the Yangtze River and the Hanjiang River, demonstrating effective pattern extraction from inland maritime traffic and high accuracy in predicting single ship trajectories, achieving a 96.7% accuracy rate and 80.9% precision. The findings suggest that the proposed method (1) effectively extracts and predicts traffic patterns, (2) identifies congestion in convergent waters, and (3) supports traffic management strategies.
... In polar navigation, VT generally comprises high-grade icebreaker serving as the LV and low-grade icebreakers as FVs. This configuration, utilizing vessels with different icebreaker capabilities, aims to maximize economic efficiency (Zhang et al., 2019;Liu et al., 2022;Liu et al., 2024). ...
Vessel train (VT) is seen as a potential application concept as it is likely to bring
environmental and economic benefits to maritime transport. Following a structured
approach, this paper analyzes the economic feasibility of VT in the ocean shipping
sector by comparing the benefits and costs of running a ship in conventional and VT
transport. Four formation transport scenarios were designed and analyzed for VT multi�scene applications considering the differences in VT composition and participation frequency. Taking the route from the Yangshan Port to the Port of Piraeus and container ships as the case study, the benefits brought by VT transport in a round trip could compensate for the increased costs when considering resistance reduction effect, but regular participation of vessels in VT transportation within a year requires the control of VT waiting time to guarantee ship productivity. Additionally, larger and slower ships in longer routes exhibit higher VT economic feasibility. It is concluded that VT can be a key element of competitive and sustainable future shipping in future as long as the resistance reduction effect in VT transport is further verified.
... The clustering performance of the DBSCAN algorithm is highly dependent on these two parameters, particularly the setting of eps, which affects the sensitivity of the algorithm to different ship densities. In the actual application process, these two parameters need to be determined through corresponding evaluation functions (Liu et al., 2022a;Zhang et al., 2021b), which will undoubtedly increase the degree of personnel participation in the supervision process. Fig. 2 illustrates an example using AIS data points from a specific moment in the waters of Ningbo Port, China. ...
With the development of intelligent ships, ships with multiple driving modes will exist in maritime traffic scenarios. The traditional methods of ship regulation, which rely on factors such as ship size, speed, and heading to identify navigation risks, are not able to accurately assess the navigation risks between ships of different autonomy levels in the context of mixed maritime traffic. The impact of a ship's autonomy level on navigation risks should also be taken into consideration. Therefore, this paper proposes a key risk ship identification method that considers the autonomy level of ships to assist in ship regulation. The method utilizes the OPTICS algorithm to cluster areas with high ship density and employs an improved Potential Risk Ship Domain (PRSD) approach to determine the Potential Collision Risk (PCR) for different autonomy-level ships, thereby constructing a directed complex network. The centrality characteristics of the network are used to identify key risk ships. Through empirical validation, the proposed method is shown to effectively determine the importance ranking of different autonomy-level ships in maritime mixed traffic scenarios. This method can provide support for regulatory agencies in the supervision and scheduling of ships in mixed scenarios.
... The ship then sails in the channel created by the icebreaker and can achieve relatively high speed with its installed power. Ship speed during convoy can easily reach over 10 knots (Goerlandt et al., 2017b;Liu et al., 2022;Zhang et al., 2019). A distance is maintained between a leading ship and a following ship in case the leading ship suddenly decelerates or comes to a halt due to e.g. ...
The capability of an icegoing ship to break out from an ice channel is a main index of its manoeuvrability in ice. Breakout is necessary if a ship needs to change its course when sailing in an ice channel. Breakout can also be used as an evasive action to avoid collision with the leading ship in emergencies during escort and convoy. Although the ice channel breakout test is documented in ITTC guidelines as a standard manoeuvring test, little data is available on the performance of icegoing ships in this context. This paper presents model-scale tests carried out at Aalto Ice Tank with a double-acting vessel with podded propulsion. Parameters including ice thickness and strength, ice channel width, initial speed and propulsive settings are varied between the tests to examine their influence on the capability and distance to break out from ice channels. In addition, stopping tests by reversing propeller revolution were conducted in ice channels to benchmark the breakout operation as an option to avoid collision. The test results reveal the influence of multiple factors on the ship's channel-breakout capability, including channel width, shaft power, initial speed, as well as thickness and strength of ice. With additional complementary numerical simulations at high speeds, it is found that for collision avoidance braking is more efficient at low speed and breakout at high speed. Recommendations on breakout test in model scale are given based on the lessons and experience learnt from the experiments.
... Acknowledging that the raw AIS data is fragmented and sometimes includes erroneous pieces of data, the AIS data is processed using a data mining method (see Liu et al., 2022). The retrieved data corresponds to the voyages of 181 different vessels. ...
Ice often complicates shipping in extremely cold regions, leading to energy-consuming, expensive transportation. Ship performance can be significantly improved with icebreaking assistance that uses specialized ships called icebreakers to create navigable pathways in ice fields. Icebreakers are a critical and expensive resource with high energy consumption that must be judiciously utilized for efficient traffic flow. Optimizing icebreaker usage requires careful consideration of multiple factors related to weather, ships, and regulations. The existing decision support tools for icebreaker management primarily aim to minimize the total waiting time of ships, which may result in allocation of excess icebreakers. The paper presents a novel simulation-based approach for decarbonizing shipping in ice by intelligent icebreaking assistance. The proposed approach optimizes icebreaker assistance for both eco-and cost efficiency, allowing for more sustainable icebreaking policies. A case study representing a simplified configuration of the Finnish-Swedish Winter Navigation System demonstrates this approach to come up with alternate operating strategies that can significantly improve the emission and/or cost (e.g., up to 7 percent less greenhouse gas emission or up to 14.2% lower costs). Results show that the proposed approach is promising, for providing recommendations on environmental and economic policies to decarbonize the Finnish-Swedish icebreaking assistance.
... The Nagel-Schrekenberg model was adopted to estimate the ship density in convoy operations, which affects the following two factors: maintaining a safe distance between ships and maintaining a safe speed. Liu et al. (2022) identified 239 icebreaker assistance operations (159 escort operations and 80 convoy operations) in the Baltic Sea based on a proposed automatic identification system, and the relative distance was statistically examined. ...
