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The maritime industry is undergoing a of Marine Autonomous Surface Ships (MASS). It is expected that, with the introduction of maritime autonomous technologies the safety performance of maritime operations increases. Nevertheless, the safety of the MASS must be properly planned and then demonstrated. This applies to the functionality of any Autonomous Navigation System (ANS). The nature of the risks related to an ANS might differ significantly from the traditional maritime risks. Therefore, mitigating these risks before applying an ANS to real-world operations is critical. This study analyses and assesses the risks of a currently developed ANS by integrating the System-Theoretic Process Analysis (STPA) and Bayesian Networks (BN) into a two-stage process. The study results provide a holistic view of the underlying risks in the ANS and the functionality of formulated Risk Control Options. The risk levels of loss events are computed within a model to represent the effects that each loss may have on the safety of the ship’s navigation and the company’s overall reputation. The assessed Risk Control Options provide information to system developers to elaborate an ANS that is safe by design. [ABSTRACT FROM AUTHOR]

AbstractThis research develops a performance evaluation model of humans in avoiding ship collision situations compared to the AI ship collision avoidance system (CAS). A human, the remote operator (RO) of Maritime Autonomous Surface Ships (MASS), ought to make compact collision avoidance (CA) decisions to secure safety and efficiency during remote operations. Hence, evaluating RO’s CA performance is important; however, research on developing evaluation methods concentrates merely on evaluating trainees based on instructor’s guidelines, while artificial intelligence (AI) makes CA decisions through parameter-based calculation. Therefore, this research proposes a CA performance evaluation model for RO of MASS based on CAS intervening of RO trainee’s simulation training in ship collision avoidance. In each time interval, the RO’s decisions showed divergent behaviors under given situational conditions compared to the CAS’s behaviors in equivalent situations. Findings denote the benefits of CAS intervention methods and RO performance evaluation model based on the proposed performance features. [ABSTRACT FROM AUTHOR]

To address the challenges posed by dense shipping traffic and the difficulty of identifying navigation risks in open waters, this paper introduces an Especial Cautious Navigation Angle (ECNA) model for ships, grounded in ship collision avoidance geometry. The ECNA model dynamically identifies the range of navigation angles where collision risks may arise between ships. Building upon this model, a comprehensive scoring algorithm is proposed to assess ship collision risks in open waters. This algorithm not only effectively tracks the evolving risk of collisions but also prioritizes ships with the most imminent danger of collision. Experimental results demonstrate that the ECNA model can accurately define the range of collision risk navigation angles. Furthermore, the scoring algorithm provides a quantitative analysis of the development trends in collision risks and offers continuous monitoring of these risks during navigation in open waters. The proposed model and algorithm exhibit strong practical applicability and operability in identifying ship collision risks in both open and dense navigable areas. These findings not only offer valuable guidance for real-world collision risk identification but also contribute to the theoretical advancement of ship collision risk analysis, presenting a novel solution to this pressing issue. [ABSTRACT FROM AUTHOR]

Autonomy is being increasingly used in domains like maritime, aviation, medical, and civil domains. Nevertheless, at the current autonomy level, human takeover in the human–autonomy interaction process (HAIP) is still critical for safety. Whether humans take over relies on situation awareness (SA) about the correctness of autonomy decisions, which is distorted by human anchoring and omission bias. Specifically, (i) anchoring bias (tendency to confirm prior opinion) causes the imperception of key information and miscomprehending correctness of autonomy decisions; (ii) omission bias (inaction tendency) causes the overestimation of predicted loss caused by takeover. This paper proposes a novel HAIP safety assessment method considering effects of the above biases. First, an SA-based takeover decision model (SAB-TDM) is proposed. In SAB-TDM, SA perception and comprehension affected by anchoring bias are quantified with the Adaptive Control of Thought-Rational (ACT-R) theory and Anchoring Adjustment Model (AAM); behavioral utility prediction affected by omission bias is quantified with Prospect Theory. Second, guided by SAB-TDM, a dynamic Bayesian network is used to assess HAIP safety. A case study on autonomous ship collision avoidance verifies effectiveness of the method. Results show that the above biases mutually contribute to seriously threaten HAIP safety. [ABSTRACT FROM AUTHOR]

In recent years, unmanned surface vehicles (USVs) have gained increasing attention in industry due to their efficiency and versatility in marine operations. Artificial potential field (APF) methods, with their strong adaptability and simplicity of implementation, are widely used in USV path planning tasks. However, the naive APF method struggles in static complex environments, due to the local minima problem. Not to mention that actual navigations may involve other dynamic traffic participants. In this work, an improved APF algorithm integrating the boundary potential field method and the International Regulations for Preventing Collisions at Sea (COLREGs) is proposed. By incorporating the boundary potential field method, this novel approach effectively reduces the computational burden caused by clusters of land obstacles in complex environments, significantly improving computational efficiency. Furthermore, the APF method is refined to ensure the algorithm strictly adheres to COLREGs in head-on, overtaking, and crossing encounters, generating smooth and safe collision avoidance paths. The proposed method was tested in numerous complex scenarios derived from electronic navigational charts. The simulation results demonstrated the robustness and efficiency of the proposed algorithm for collision avoidance within complex maritime environments, providing reliable technical support for autonomous obstacle avoidance in dynamic ocean conditions. [ABSTRACT FROM AUTHOR]

With the increasing proportion of ships in logistics and the growing prosperity of traffic in maritime, negotiation and cooperative collision avoidance between ships is becoming more and more essential for navigational safety. This paper proposes a Model Predictive Control method that utilizes intention data of the target ship and a quaternion ship domain model to achieve collision avoidance while considering COLREGs, named IQMPC. Firstly, by utilizing the intention data of other ships, trajectories of the own ship and the target ship are well predicted to detect potential collision risks and take optimal avoidance actions in advance while risks exist. Secondly, the quaternion ship domain with its adjacent area is divided into four different parts to reflect the urgency of ship encounters. Collision risk evaluation functions are designed to determine avoidance actions conforming to COLREGs. Thirdly, several different ship encounter scenarios were simulated based on IQMPC to verify its capability. [ABSTRACT FROM AUTHOR]

The 2011 Fukushima disaster and the 2020 COVID-19 pandemic are two major 21st century events that were least expected while being highly disruptive, having an immediate as well as longer-term impact on shipping operations. However, while pandemics are a recurrent phenomenon of the "known-knowns" type, the combination of phenomena which led to Fukushima had no assigned probability; hence, no preparedness was in place, as this was practically a unique occurrence in shipping. Considering significant shipping incidents of various less or more uncommon etiologies, such as the capsizing of vessels, missile attacks on merchant ships or vessel-onto-bridge collisions, this conceptual paper puts forward a consequence-based approach for assessing and managing shocks in the maritime domain, especially the ones classified in the "unknown-unknowns" or "Black Swan" categories. In the context of preparedness theory, the authors propose the adoption by shipping businesses, in parallel to any other risk approaches and tools, of the Assessment-reaction-Recovery-Conversion (ArRC) framework for managing risk and of relevant key recovery indicators which may assist in (a) increasing resilience through focusing the recovery planning on consequence-oriented, root-neutral reactions and (b) in promoting a "bounce-back-better" frame of mind and action plan, contributing to faster and easier recovery after a shock of any type. [ABSTRACT FROM AUTHOR]

The exploration of ship collision avoidance behavior characteristics can provide a theoretical basis for ship collision risk assessment and collision avoidance decision-making, which is significant for ensuring maritime navigation safety and the development of intelligent ships. In order to scientifically and effectively analyze the characteristics of ship collision-avoidance behavior and to seek the intrinsic connections among ship collision-avoidance behavior feature parameters(CABFPS), this study proposes a method that combines the Apriori algorithm and complex network theory to mine ship collision-avoidance behavior characteristics from massive AIS spatiotemporal data. Based on obtaining ship encounter samples and CABFPS from AIS data, the Apriori algorithm is used to mine the association rules of motion parameters, and the maximum mutual information coefficient is employed to represent the correlation between parameters. Complex networks of CABFPS for different encounter situations are constructed, and network topological indicators are analyzed. Mutual information theory is applied to identify key parameters affecting ship collision- avoidance behavior under different situations. The analysis using actual AIS data indicates that during navigation, the relationships among various parameters are closely linked and prone to mutual influence. The impact of CABFPS on ship collision-avoidance actions varies under different encounter scenarios, with relative distance and DCPA having the greatest influence on ship collision-avoidance actions. This method can comprehensively and accurately mine the correlations between CABFPS and the influence mechanism of parameters on collision-avoidance actions, providing a reference for intelligent ship navigation and the formulation of collision-avoidance decisions. [ABSTRACT FROM AUTHOR]

Autonomous navigation for ships is recognised as a pivotal trend in the future maritime industry, especially autonomous avoidance collision decision-making in complex multi-ship encounter scenarios, which constitutes a significant area of research. This paper presents an adaptive autonomous navigation decision system for ships, which addresses the problems posed by intricate situations. A dynamic collision risk index (CRI) model based on the dangerous manoeuvring intervals is established, derived using an improved velocity obstacle (VO) algorithm, which incorporates ship manoeuvrability constraints and the Convention on International Regulations for preventing collisions at sea (COLREGs). Autonomous navigation decision-making is achieved by combining the fuzzy PID (Proportional–Integral–Derivative) course control method and the trajectory tracking of the adaptive Line-of-Sight (LOS) algorithm. Combining the Model Predictive Control (MPC) idea, this approach enables ships to navigate autonomously and adaptively in challenging water conditions. To evaluate the effectiveness of the proposed approach, two case studies involving the five-ship encounter situation and the six-ship encounter situation are conducted. The results demonstrate that the presented autonomous navigation decision-making approach efficiently tracks the planned route while safely avoiding all target ships. Moreover, the decision-making exhibits adaptability in coping with the dynamic manoeuvres of the target ships, including alterations in the course and changes in speed. These findings confirm that the proposed system significantly enhances the ability of autonomous ships to navigate safely and adaptively in complex multi-ship encounter scenarios, demonstrating its practical relevance and effectiveness for real-world maritime applications. [ABSTRACT FROM AUTHOR]

Escort operation is an effective mean to ensure the safety of ship navigation in the Arctic ice area and expand the window period for ship navigation. At the same time, the operation mode between icebreaker and escorted ship may also causes collision accident. In order to scientifically reflect the complex coupling relationship in the escort operation system in Arctic waters and effectively manage the navigation risks. This study proposes to use the functional resonance analysis method (FRAM) to identify the risk factors of ship escort operation in Arctic waters, and uses the Bayesian network (BN) method to establish a risk assessment model for escort operation collision accident. The cloud model is used to process the uncertain data information. The proposed method is applied during the actual escort operation of a commercial ship on the Arctic Northeast Passage. According to the model simulation results, the risk performance of ship escort operation in Arctic waters is quantitatively analyzed, and the key risk causes are further analyzed. This study has positive significance for better understanding the risk evolution mechanism of ship escort operation in Arctic ice area and helping relevant management departments to take risk control measures. [ABSTRACT FROM AUTHOR]

An integrated quantitative risk analysis methodology based on the BT (bow-tie) and FBN (fuzzy Bayesian network) is developed in the present study to evaluate the risk evolution from causes to consequences of engine room fires on ships. Given limited historical statistics on engine room fire accidents, a probabilistic estimation model based on fuzzy sets is employed to determine prior probabilities of BN nodes. A case study of the engine room fire is carried out to demonstrate the soundness and applicability of the proposed methodology. Moreover, scenario analysis is implemented to assess how safety barriers can mitigate escalation of consequences triggered by engine room fires, while sensitivity analysis ranks critical hazards and quantifies correlations between different consequences and risk events within engine room fires. The results indicate that mechanical faults, improper bunker operation, improper maintenance, circuit overload or short circuit and insulation aging or damage are the main direct risk events triggering engine room fires on ships. The effectiveness of safety barrier (fire extinguishing devices) can play a decisive role in preventing further escalation of controlled fire incidents. [ABSTRACT FROM AUTHOR]

Floating bridges face potential hazards due to ship collisions throughout their operational lifetime. In a situation where a pontoon is significantly damaged from an accident, a floating drydock may be used to compensate for the lost buoyancy and provide a dry atmosphere for operations. As the repair might take months, a primary concern is whether the repair can be in-site conducted without shutting down the road traffic. This study aims to investigate the feasibility of using a drydock for the repair. The numerical model of the in-operation damaged bridge is established for a comparative dynamic analysis with the intact end-anchored bridge. Eigenvalue analysis is conducted, and pendulum modes of oscillation are found with an eigen-period of around 15 s. The dynamic responses are analyzed through a series of fully coupled time-domain simulations under various environmental conditions. The results indicate that the standard deviation of the moment about the girder weak axis increases significantly at the damaged pontoon axis due to the excitation of low-frequency resonant response. Swell wave loads might induce dynamic amplification to the damaged bridge, even with a relatively small wave height. In addition, the internal stress of the bridge girder is investigated and found to be larger, especially, at the lower locations of the cross section. It is suggested that the responses can be managed by limiting the excitation of pendulum modes or providing special damping devices in practical engineering. [ABSTRACT FROM AUTHOR]

Simple Summary: The welfare of free-ranging cetaceans is being impacted around the world due to human activities like commercial fishing and marine traffic. Here, we validate a non-invasive physical indicator of welfare for humpback and fin whales found in the Gulf of St-Lawrence, Canada. Multi-scale measurement of welfare showed that most humpback whales were in a good welfare state, whereas most fin whales were in a moderate state. For both species, welfare was mainly affected by prolonged effects of physical trauma (entanglement in fishing gear and boat collisions) on body condition, specifically whales being thinner. Other factors impacting welfare included degradation of the marine environment (e.g., oxygen levels, water temperatures and salinity levels). Anthropogenic activities impacting marine environments are internationally recognized as welfare issues for wild cetaceans. This study validates a first evidence-based physical indicator for the welfare assessment protocol of humpback (n = 50) and fin whales (n = 50) living in a highly anthropized environment. Visual assessments of body condition, skin health, prevalence of injuries and parasite/epibiont loads were performed using a species-specific multi-scale measuring tool. A total of 6403 images were analyzed (fin, n = 3152; humpback, n = 3251) and results were validated through reliability and positive discrimination statistical tests. Based on physical measures, welfare assessment results showed that 60% of humpback whales were considered in a good welfare state compared to only 46% of fin whales. Significant relationships were observed in both species, between environmental parameters like dissolved oxygen levels, and prevalence of cutaneous lesions like pale skin patch syndrome. Furthermore, animals with injuries due to anthropogenic activities were more likely to be in poorer body condition, suggesting chronic stress affecting welfare. [ABSTRACT FROM AUTHOR]

Ship trajectory prediction plays a key role in the early warning and safety of maritime traffic. It is a necessary assistant tool that can forecast a ship's trajectory in a certain period to prevent ship collision. However, highly precise prediction of long-term ship trajectories is still a challenge. This study proposes a ship trajectory prediction model called ShipTrack-TVAE, which is based on a Variational Autoencoder (SocialVAE) and Transformer architecture. It aims to address ship trajectory prediction tasks in complex waterways. To enable the model to avoid potential collision risks, this study designs a collision avoidance mechanism, which comprehensively incorporates safety constraints related to the distance between ships into the loss function. The experimental results show that on the Qiongzhou Strait ship AIS dataset, the Average Displacement Error (ADE) of ShipTrack-TVAE improved by 21.85% compared to the current state-of-the-art trajectory prediction model, SocialVAE, while the Final Displacement Error (FDE) improved by 17.83%. The experimental results demonstrate that the ShipTrack-TVAE model can effectively improve the prediction accuracy of short-term, medium-term, and long-term ship trajectories. It has excellent performance and provides a certain reference value for advancing unmanned ship collision avoidance. [ABSTRACT FROM AUTHOR]

With the rapid development of autonomous collision avoidance algorithms on ships, the technical demand for the testing and verification of autonomous collision avoidance algorithms is increasing; however, the current testing of autonomous collision avoidance algorithms is mainly based on the virtual simulation of the computer. To realize the testing and verification of the autonomous collision avoidance algorithm in the real ship scene, a method of virtual reality fusion testing in open water is proposed and real ship testing is carried out. Firstly, an autonomous ship collision avoidance test and evaluation system is established to research the test method of ship encounters in open water. Starting from the convention on the international regulations for preventing collisions at sea (COLREG), the main scenario elements of ship collision avoidance are analyzed. Based on the parametric modeling method of ship collision avoidance scenarios, a standard test scenario library for ship collision avoidance in open waters is established. Then, based on the demand for a ship collision avoidance function test, the evaluation index system of ship collision avoidance is constructed. Subsequently, for the uncertainty of the initial state of the real ship test at sea, the virtual–real space mapping method to realize the correspondence of the standard scenario in the real world is proposed. A standardized testing process to improve testing efficiency is established. Finally, the method of conducting virtual simulation and virtual reality fusion tests for various scenarios are verified, respectively. The test results show that the test method can effectively support the testing of autonomous collision avoidance algorithms for ships in open waters and provide a practical basis for improving the pertinence and practicability of ship collision avoidance testing. [ABSTRACT FROM AUTHOR]

Path planning and collision avoidance issues are key to the autonomous navigation of unmanned surface vehicles (USVs). This study proposes an adaptive differential evolution algorithm model integrated with the analytic hierarchy process (AHP-ADE). The traditional differential evolution algorithm is enhanced by introducing an elite archive strategy and adaptively adjusting the scale factor F and the crossover factor C R to balance global and local search capabilities, preventing premature convergence and improving the search accuracy. Additionally, the collision risk index (CRI) model is optimized and combined with the quaternion ship domain, enhancing the precision of CRI calculations and USV autonomous collision avoidance capabilities. The improved CRI model, the International Regulations for Preventing Collisions at Sea, and the optimal collision avoidance distance were incorporated as evaluation factors in a fitness function assessment, with weights determined through the AHP to enhance the rationality and accuracy of the fitness function. The proposed AHP-ADE algorithm was compared with the improved particle swarm algorithm, and the performance of the algorithm was comprehensively evaluated using safety, economy, and operational efficiency. Simulation experiments on the MATLAB platform demonstrated that the proposed AHP-ADE algorithm exhibited better performance in scenarios involving multiple ship encounters, thus proving its effectiveness. [ABSTRACT FROM AUTHOR]

Ship collision accidents have a greatly adverse impact on the development of the shipping industry. Due to the uncertainty relating to these accidents, maritime risk is often difficult to accurately quantify. This study innovatively proposes a comprehensive method combining qualitative and quantitative methods to predict the risk of ship collision accidents. First, in view of the uncertain impact of risk factors, the Bayesian network analysis method was used to characterize the correlations between risk factors, and a collision accident risk assessment network model was established. Secondly, in view of the uncertainty relating to the information about risk factors, a subjective data quantification method based on the cloud model was adopted, and the quantitative reasoning of collision accident risk was determined based on multi-source data fusion. The proposed method was applied to the spatiotemporal analysis of ship collision accident risk in China's coastal port waters. The results show that there is a higher risk of collision accidents in Guangzhou Port and Ningbo Port in China, the potential for ship collision accidents in southern China is greater, and the occurrence of ship collision accidents is most affected by the environment and operations of operators. Combining the Bayesian network and cloud model and integrating multi-source data information to conduct an accident risk assessment, this innovative analysis method has significance for improving the prevention of and response to risks of ship navigation operations in China's coastal ports. [ABSTRACT FROM AUTHOR]

Offshore wind energy is characterized by its clean and renewable nature, leading to rapid growth in the industry. However, the incidence of ship collisions with offshore wind turbines has also risen with the increasing number of offshore wind farms, particularly in commercial shipping lanes. To gain a thorough understanding of dynamic response between wind turbines and vessels, this paper extensively reviews studies related to wind turbine–ship collisions over the past 2 decades to cover four key aspects: (i) the fundamental requirements and background of collision analysis study, (ii) the analysis of dynamic response and collision characteristics of the fixed-bottom and floating offshore wind turbines (OWTs) subjected to ship collision forces, (iii) the influence of key collision factors that include impact positions, initial ship kinetic energy, and soil–structure interaction on the structural response for the wind turbines, and (iv) a discussion of protection measures to mitigate the collision damage to the substructure. The limitations in the existing studies are discussed, and future research directions are suggested. [ABSTRACT FROM AUTHOR]

After the near-complete cessation of commercial whaling, ship collisions have emerged as a primary threat to large whales, but knowledge of collision risk is lacking across most of the world’s oceans. We compiled a dataset of 435,000 whale locations to generate global distribution models for four globally ranging species. We then combined ’35 billion positions from 176,000 ships to produce a global estimate of whale-ship collision risk. Shipping occurs across 92% of whale ranges, and <7% of risk hotspots contain management strategies to reduce collisions. Full coverage of hotspots could be achieved by expanding management over only 2.6% of the ocean’s surface. These inferences support the continued recovery of large whales against the backdrop of a rapidly growing shipping industry. [ABSTRACT FROM AUTHOR]

The western Alpine belt is the focal point of moderate but constant seismic activity. Numerous geodynamic and seismological studies underline the many scientific questions linked to Alpine dynamic processes and the associated rate of deformation resulting from late continental collision phases, and the assessment of seismic hazard and its associated risks. Seismic monitoring in the northern French Alps was launched in 1987 with the installation of the first seismological network, hosted by the Earth Science Observatory at Grenoble Alpes University. Since then, the network has been updated over the years, keeping pace with technical developments in seismic instrumentation, monitoring and data management. The homogenization of information described in this scientific data paper is motivated by the need for a single instrumental seismic catalogue, consisting in arrival times picks and hypocenters using the same velocity model. The final catalogue SISMalp-1987–2023 (CC-BY-4.0) contains 50,822 weak-to-moderate earthquakes with local magnitude between −1.8 and 5.0; it can serve as a basis for all general seismotectonic and risk assessment studies in the region. [ABSTRACT FROM AUTHOR]

The integrity of large crossing cables is frequently compromised by inland river ultra‐high sand dredgers, leading to severe safety incidents. To mitigate these risks, height‐limiting mechanisms, known as river‐blocking lines, are essential on both sides of the large crossing cable. Traditional river‐blocking lines are typically rigid structures, posing challenges for both the river‐blocking line and passing ships. To address this issue and enhance safety measures, this study introduces a novel flexible blocking device. Initially, the fundamental principles of suspension cable theory are employed to design the river‐blocking line. By leveraging energy conversion principles, heavy objects are suspended at the cable ends to convert the kinetic energy of oncoming ships into potential energy during collisions. Subsequently, a structural model for a three‐suspension cable river‐blocking line is developed. Finite element simulations confirm the model's efficacy, aligning with theoretical expectations. Furthermore, a scaled prototype of the model is constructed to assess project feasibility and reliability. The results affirm that the flexible blocking device can serve as an effective height‐limiting mechanism, proficiently impeding passing ships, mitigating impact loads, safeguarding vessels, and offering direct physical protection for ultra‐high voltage (UHV) large‐span cables. [ABSTRACT FROM AUTHOR]

The downward trend in the number of fatalities and serious injuries related to road accidents depends on the implementation of increasingly performing Advanced Driver Assistance Systems (ADAS) in the circulating fleet. The greatest benefit of the adoption of ADASs like Autonomous Emergency Braking (AEB) consists in limiting the frequency of impacts. However, in Inevitable Collision States (ICSs), the decrease in impact closing speed guaranteed by the AEB may not reduce the Injury Risk (IR) for the occupants: IR is a function of the vehicle's velocity change in the collision ( Δ V ) – a combination of impact closing speed and impact eccentricity. The work virtually analyses, in lane departure ICS scenarios, the performance of an adaptive steering and braking intervention logic based on instantaneous IR minimization. The adaptive logic reduces IR compared to the absence of intervention (down to 80 times lower) and to the AEB (down to 40 times lower) by leading the ego vehicle toward eccentric impact configurations. It is highlighted that full activation of the steer-by-wire system in 0.3 s allows the adaptive logic to also reduce the frequency of impacts; it is further evidenced that employing a function capable of modulating the braking level to minimize IR entails disadvantages from the IR perspective compared to the AEB: efficient intervention strategies on the steering are the only alternative for increasing the safety provided by high-performance ADASs. Finally, compared to previous literature, the study highlights high efficiencies of the adaptive logic in a wide range of ICS scenarios. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the dynamic nonlinear problem of bridge loads and responses during ship collisions, a design method for bridge anti-collision structures based on nonlinear numerical simulation was proposed. The author describes in detail the entire process of collision force evolution, energy conversion, and plastic deformation of the anti-collision energy dissipator, and conducts a comprehensive simulation of it. The experimental results show that when a ship with a mass of 1000 tons collides forward at speeds of 1, 3, and 5 meters per second, the collision depth is 0.23, 1.46, and 3.95 meters, respectively, less than the maximum allowable collision depth of 4.3 meters, and the collision energy dissipator is still in the protective working state for the bridge pier. When a ship with a mass of 3000 tons collides with the collision avoidance energy dissipator at a speed of 3 or 5 meters per second, the collision depth exceeds the maximum allowable collision depth, and the collision avoidance energy dissipator fails, the ship will directly collide with the wharf. The plastic deformation of the anti-collision energy dissipator provided has important reference value for design. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The poor maneuverability inherent to large ships is a non-negligible problem that restricts the development of the shipping industry, as large ships can only cruise at an excessively conservative speed when they encounter complicated traffic conditions; nevertheless, ship collision accidents still occasionally occur. In the present study, the novel concept of spoiler fins for modern large ships is proposed. In order to assess their effectiveness in enhancing ship maneuverability, a KRISO container ship (KCS) was selected to carry a pair of spoiler fins, after which a simplified simulation approach for saving the calculation resource was designed for ship collision avoidance conditions, and a full-scale numerical model, including the ship hull, fin, and fluid field domain, was established. Transient-state hydrodynamic forces were calculated during collision avoidance maneuvers using the CFD method; the pressure and velocity contours around the ship were demonstrated; and the ship motion trajectories under different initial ship speeds were simulated and predicted through the adoption of overset mesh and 6-DOF dynamic mesh techniques. Eventually, the improved course-changing performance, dependent on the spoiler fins, was validated. [ABSTRACT FROM AUTHOR]

The Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs) stipulates ships' obligations when encountering each other. However, human action remains a primary cause of collision accidents. In the complex environment of mixed navigation involving MASS and manned ships, the applicability of the COLREGs for determining the give-way ship has faced certain challenges. Therefore, this study proposes a model for determining the give-way ship, combining ship characteristics and using an asymmetric Gaussian function to construct the potential field of stand-on ships from the perspective of give-way ships. It constructs the cost function based on field theory to determine the respective avoidance costs for both ships in a crossing situation, with the ship incurring the lowest cost selected as the give-way ship, followed by a case study to validate the model. The research is dedicated to coordinating avoidance action objectively, effectively reducing maritime collisions, and providing exploratory guidance for collision avoidance decision-making in future mixed navigation environments. [ABSTRACT FROM AUTHOR]

With the rapid advancement of new-generation information technology, the virtual–real fusion interaction has increasingly become a crucial technique for structural analysis to determine the strength envelope of hulls. A high-precision assembly of the experimental devices in a virtual environment is vital. A virtual assembly method for a structural virtual–real fusion test based on the oriented bounding box (OBB) algorithm, the Devillers and Guigue algorithm, and differential triangle facets algorithm are proposed in this paper. The experiment of the connector in a typical offshore floating platform is performed as a case, which indicates that the virtual assembly method proposed in this paper enables the assessment of assembly virtually prior to the actual experiment, and the assembly accuracy can reach 0.01 mm. The digitalization and virtual–real fusion interaction for the mechanical experiment of hulls are advanced to ensure efficiency, safety, and economy. [ABSTRACT FROM AUTHOR]

As more and more ships sail on the sea, the probability of collision between ships also increases. At present, researches more on head-on ship collisions than oblique ship collisions. According to statistical data, the probability of oblique ship collision is higher than that of head-on ship collision, and oblique ship collision may cause a wider range of structural damage. Therefore, this paper studies the damage deformation of ship side structures in oblique collision scenarios. In this paper, a simplified analysis method is proposed to predict the structural response of the struck ship's side structures by bulbous bow in oblique collision scenarios and the analytical results match well with the numerical simulation results, which verifies the accuracy of the simplified analysis method. The simplified analysis method can be used to assess the crashworthiness of ship side structures by bulbous bow in oblique collision scenarios. [ABSTRACT FROM AUTHOR]

Accurate forecasting of ship encounter positions is crucial for preventing collisions at sea. This paper presents a framework for predicting a ship's trajectory using a sparse Gaussian process. The proposed method effectively addresses the limitations of existing full Gaussian processes, specifically the significant storage requirements and time complexity associated with data training. The model is trained using Automatic Identification System (AIS) data on trajectories, with hyperparameters optimized through a genetic algorithm. Experimental analysis demonstrates that the proposed model reduces average time complexity by 61.3 s and improves average prediction error to 9.2 m compared to full Gaussian-process-based models. [ABSTRACT FROM AUTHOR]

An offshore installation is exposed to ship collision risk from in-field and passing vessels. Both categories of collision have occurred on the United Kingdom Continental Shelf (UKCS), and both have the potential to result in catastrophic damage to the installation, although to date only significant consequences have been observed in UK waters. World-wide, catastrophic collisions with installations have occurred resulting in severe damage to vessels and installations, leading to loss of life and environmental damage. This led to the authors investigate the occurrence and reporting of ship to platform collisions on the UKCS 1971–2017. It was found that there were periodic fluctuations in the occurrence of collision accidents. This research analyses the accident trends in order to determine the whether the fluctuations were a regular occurrence and, if so, what was the cause. 511 ship to platform collision incidents between 1971 and 2017 were subject to analysis, in terms of damage classification, the vessel type, month of occurrence and a comparison of the release of regulations with the fluctuation of incidents. Subsequently, this analysis has identified a key trend between the reporting of offshore collision incidents and the release and enforcement of offshore Safety Case regulations. [ABSTRACT FROM AUTHOR]

Discussions surrounding Maritime Autonomous Surface Ships (MASS) are occurring in academia, industry, and the International Maritime Organization (IMO). Automatic collision avoidance, as one of the key technologies of MASS, is the core of the autonomous navigation function of MASS, and its role is to solve the autonomous collision avoidance problem during MASS navigation. Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) is a fundamental basis for automatic collision avoidance, and the navigation of MASS should adhere to it. However, the applicability of MASS to COLREGS has not yet been resolved. Responding to these issues, the paper proceeds to analyze the principal challenges of MASS to COLREGS in terms of the application of MASS to good seamanship, the neglect provision, the lookout provision, the insight of one another provision, and the problems of the deviation provision. Furthermore, suggestions are put forth for the revision of COLREGS, including the mode of revision, the reconstruction of MASS collision liability, the long-term coexistence of MASS and traditional ships, and the risk control of COLREGS revision in the context of artificial intelligence. These suggestions aim to establish a foundation for a more effective adaptation to the advent of the MASS era. [ABSTRACT FROM AUTHOR]

This research addresses the crucial problem of collision avoidance decision making for autonomous ships under diverse encounter situations. Building upon the Deep Deterministic Policy Gradient (DDPG) algorithm, appropriate reward functions based on the International Regulations for Preventing Collisions at Sea (COLREGS) have been designed to effectively guide intelligent agents in acquiring optimal strategies. By incorporating the concept of potential reward shaping, the proposed approach ensures efficient obstacle avoidance while adhering strictly to the established rules. Moreover, extensive simulations have been conducted to validate the algorithm’s performance in collision avoidance for both dual-ship and multi-ship scenarios under varying encounter situations, and a comparative analysis with the TD3 algorithm has been undertaken. The obtained results demonstrate that the proposed algorithm exhibits rapid convergence and stable training performance. The resulting models successfully achieve collision-free navigation while strictly adhering to the COLREGS. Particularly, in two-ship encounter situations, the proposed algorithm outperforms the trajectory planned by the TD3 algorithm in terms of shorter path length and higher efficiency. [ABSTRACT FROM AUTHOR]

The situation of two ships maneuvering in the vicinity is not so rare, and the significant hydrodynamic interaction effect always poses a threat to navigation safety in these conditions. The assessment of the Distance at Closest Point of Approach (DCPA) is necessary for ship collision avoidance decision-making. In this study, an efficient ship maneuvering model for close-distance maneuvering is developed to predict DCPA rapidly, where the hydrodynamic interaction between ships is accounted for. The Maneuvering Modeling Group (MMG) standard model is used to predict ship motion, and the hydrodynamic interaction effect is estimated in real-time by a code based on the potential flow theory where the variation of free surface is neglected. The ship maneuvering model is validated by the comparison between simulation and experiment in turning and zig-zag maneuvering; furthermore, the validated maneuvering model is used to predict the trajectory under the ship hydrodynamic effect. The characteristic of ship maneuvering under the ship hydrodynamic interaction between two ships is described and illustrated, and the influence of the velocity and lateral distance on the ship trajectory is revealed. A sensitivity analysis of the maneuvering model is performed to determine whether the hydrodynamic interaction effect is necessary to be evaluated exactly for an accurate predicted trajectory and DCPA. The DCPA in different situations is calculated, which represents the ship collision risk. [ABSTRACT FROM AUTHOR]

The article discusses the creation of wooden replicas of great auk eggs by Stephen James Goodall in 1922. These replicas were sought after due to the scarcity of actual great auk relics. Goodall meticulously painted the replicas based on illustrations, with some minor discrepancies in color and maculation. Despite these differences, the replicas are considered among the most realistic in terms of size, shape, and color. The article provides detailed information on the construction and provenance of these replica eggs, shedding light on the craftsmanship involved in their creation. [Extracted from the article]

The United States Navy plans on fielding autonomous surface vessels in the near future. This paper presents a preliminary approach for certifying an autonomous surface vessel to complete a transoceanic voyage. In particular, this paper will decompose the rules currently outlined by the Convention on the International Regulations for Preventing Collisions at Sea for avoiding a collision when two vessels are in sight of one another in international waters. These requirements are the basis for a specification that we examined to ensure it meets the requirements of the convention. We developed a protocol based on the analyzed specification that will ensure what the vehicle will function appropriately while operating autonomously. We then test this protocol using real-world scenarios currently used to certify human operators. Finally, we showed that if the protocol had been in place during a fatal mishap within the naval surface warfare community the collision would have been avoided. This paper describes how this protocol can be used as evidence for certifying an autonomous controller to complete a task reserved for a fully qualified ship's Commanding Officer in the United States Navy. [ABSTRACT FROM AUTHOR]

The Yangtze River estuary in China is characterized by a complex maritime geographical environment and presents significant challenges to ship manoeuvring and control, thereby increasing the risk of ship collision accidents. Based on the 2013–2022 shipwreck investigation report published by Shanghai and Zhejiang Maritime Safety Administration, this paper analyses the primary factors responsible for ship collision accident severity in the Yangtze River estuary from four aspects, namely ship, environment, human and management. Utilizing accident severity as the dependent variable and 24 factors, including ship type, gross tonnage, wind speed, operational errors and so on, as independent variables, the study employed a stepwise regression approach to filter the variables. Subsequently, an ordered probit regression model was constructed based on the 10 most influential variables, followed by a marginal effect analysis. The findings indicate that a ship's gross tonnage, wind speed, ocean current speed, offshore distance and day/night conditions significantly influence the likelihood of different accident levels. Specifically, wind speed, offshore distance and ocean current speed have a negative impact on minor and general accidents while positively affecting major and severe accidents. Gross tonnage and daytime/nighttime have a positive impact on minor and general accidents but negatively impact major and severe accidents. Moreover, general accidents exhibit the most pronounced marginal effect for each explanatory variable. The findings can help the shipping authorities to identify the causes of ship collision accidents and take effective measures to reduce such accidents, thereby enhancing the safety of ship navigation in the area. [ABSTRACT FROM AUTHOR]

In order to ensure the safety of navigation in a bridge area, and based on the theory of the safety potential field, a method of ship safety assessment and early warning in an inland river bridge area is proposed. Firstly, the risk elements associated with ship collisions in a bridge area are classified. Secondly, these risks are quantified using the potential energy field, the boundary potential field and the behavioural field, and then the ship state under the influence of wind flow, predicted by the Kalman filter, is quantified using the kinetic energy field. Then, the above four potential energy fields are merged to obtain a superposition field, and the magnitude of the instantaneous risk in the bridge area is obtained based on its magnitude. Finally, the change of field strength values under different moments is used for early warning. The results of the simulation of a ship passing through the piers of the Baijusi Bridge show that the model can effectively quantify the risk of a ship–bridge collision in the inland bridge area and provide real-time warning of the risk of a ship–bridge collision in the bridge area, which is of great significance for improving the safety of the inland bridge area. [ABSTRACT FROM AUTHOR]

In order to study the collision of sea ice on bridge piers of a sea-crossing bridge, this study establishes a finite element model of the impact of sea ice on bridge piers in aqueous media based on explicit dynamics analysis software and programming software using the arbitrary Lagrangian Eulerian (ALE) method. The results show that, when the sea-ice spacing is larger than the sea-ice edge length, the increase in sea-ice spacing leads to a decrease in the collision force and a significant increase in the probability of climbing and overturning. The increase in sea-ice mass significantly increases the impact force on the bridge abutment, and the peak value increases linearly with the increase in mass, and the sea-ice climbing and overturning phenomena are obvious. Different shapes of sea ice are obtained by cutting the sea-ice field with the two-dimensional Voronoi method, and the maximum impact force increases significantly with the increase in the average area. Irregularly shaped sea ice leads to a larger impact force and triggers the accumulation climbing phenomenon, which is verified by experiments, and the experimental values are in good agreement with the simulated values. In conclusion, this study reveals the significant effects of the spacing, mass, and shape of sea ice on the impact force of bridge piers, which provides an important reference for the design of bridge structures. [ABSTRACT FROM AUTHOR]

With the development of artificial intelligence technology, the future water traffic environment will present a new pattern of coexistence of manned ships and unmanned ships, because unmanned ships are different from manned ships in situation understanding, collision avoidance decision-making, and so on. Therefore, the obstacle avoidance planning between unmanned ships and manned ships becomes extremely complex, and collision avoidance behavior scheme deduction becomes a key step in solving the problems related to situation understanding and collision avoidance decision-making in collision avoidance scenarios. In this paper, the situation understanding of the pilot for different collision avoidance situations is integrated into the dynamic obstacle avoidance model, and an intelligent navigation collision avoidance system is proposed to assist in deducing the collision avoidance action plan of the unmanned ship in the man–machine coexistence scenario. The intelligent navigation collision avoidance system is divided into two parts, namely a ship situation understanding part and a ship obstacle avoidance part, wherein ship situation understanding is used for realizing the transition of the collision state of the unmanned ship in the deduction process by constructing a collision-state set and a behavior decision set by using a finite state machine (FSM). Regarding ship obstacle avoidance, ship velocity obstacle is calculated based on the reciprocal velocity obstacle method (RVO), and the collision avoidance action is selected by using the behavior decision generated by the FSM to realize the dynamic collision avoidance deduction of the unmanned ship. In this study, the validity and effectiveness of the intelligent navigation collision avoidance system proposed in this paper are verified by case studies in a variety of collision avoidance scenarios. The system successfully solves the problem of intelligent collision avoidance planning, provides reliable support for the intelligent collision avoidance of unmanned ships, provides a feasible solution for safety and efficiency in sea navigation, and provides a valuable reference for the design and development of future intelligent navigation collision avoidance systems for ships. [ABSTRACT FROM AUTHOR]

The Friesen bridge near Weener – Europes largest lift‐swing‐bridge In December 2015, the historic railway bridge over the Ems River near Weener was destroyed by a ship collision. The movable bridge part of the Friesen bridge, a rolling bascule bridge (Scherzer bridge) was so severely damaged that it could not be repaired. After an intensive political discourse, it was decided to rebuild the bridge. A feasibility study determined that, considering all conditions, the reconstruction of the Friesenbrücke as a lift‐swing bridge is the preferred option. The bridge structure of the Friesenbrücke has a total length of 337 m, with the centerpiece being the approx. 145 m long movable truss section of the lift‐swing bridge. The new Friesenbrücke provides a clear width of 56.60 m for shipping and meets the safety and ease‐of‐navigation requirements for all affected traffic routes. The new Friesenbrücke in the northwest of Lower Saxony is a major project that is unique in its structural dimensions and logistical conditions. It will become the largest lift‐swing bridge for railway traffic in Europe. [ABSTRACT FROM AUTHOR]

This work addresses the issue of multi-ship collision avoidance decision-making complex encounter situations, and proposes a novel velocity varying-steering collision avoidance method based on an improved particle swarm optimization (IPSO) algorithm. The proposed method establishes a limited range based on the International Regulations for Preventing Collisions at Sea (COLREGs) and creates a multi-objective model, in which the collision risk of ships, the energy loss caused by velocity varying and the voyage loss caused by steering are taken into account. To obtain an optimal solution of the multi-objective model, an IPSO is introduced to determine the feasible solution domain for ship collision avoidance decision making(CADM). The proposed CADM is validated by numerical simulations and navigation simulator. The results indicate that the recommended velocity and course can effectively remove the risk of collision between the ship and target ships. [ABSTRACT FROM AUTHOR]

With the rise of artificial intelligence, ships are gradually becoming intelligent. Ship path planning, as the foundation of ship intelligence, has become a current research hotspot. To achieve the planning of ship collision avoidance paths, a hybrid ant colony algorithm and artificial potential field for optimal safety path planning was proposed. The model makes up for the disadvantages of the slow convergence rate and the easy local optimum. At the same time, the ant colony algorithm in turn makes up for the poor global search ability of the artificial potential field method, so that the algorithm can achieve accurate path planning. The test results show that in a simple environment, the hybrid ant colony algorithm, improved tangent and Dijkstra algorithm, and improved fast extended random tree * algorithm iterated about 7, 25, and 40 times respectively before starting to converge; In complex environments, the improved tangent and Dijkstra algorithms do not converge, while the improved fast expanding random tree * algorithm and hybrid ant colony algorithm iterate about 40 and 8 times respectively to begin convergence. It is clear that the mixed ant colony algorithm converges fast and can obtain the optimal path in the shortest time. The number of unsafe path points for the optimal path in a simple environment is 6, 1, and 0, respectively, for the improved tangent and Dijkstra algorithm, the improved fast expanding random tree * algorithm, and the hybrid ant colony algorithm; The number of unsafe path points for the optimal path in a complex environment is 9, 3, and 0, respectively; It can be seen that the path planned by the hybrid ant colony algorithm has higher security. The above results show that the mixed ant colony algorithm can effectively shorten the search time of optimal paths while improving the security of pathways. [ABSTRACT FROM AUTHOR]

Ship lock project currently demonstrates a distinct cyclical pattern, accumulating latent hazards that pose a significant threat to project safety. Seepage safety (the condition in which the seepage risk is reduced to an acceptable level) serves as a crucial indicator in the safety risk assessment index system for ship lock project construction, thus necessitating an in-depth analysis of the risk factors impacting seepage safety. Utilizing a ship lock project in China as a case study, this study employs the finite element method (FEM) to analyze the seepage field of the ship lock foundation pit basin and proposes a comprehensive set of methods for risk evaluation and warning models pertaining to seepage safety risks in ship lock engineering. This study reveals that the obstruction of dewatering wells and imperfections in the diaphragm wall are the primary factors contributing to seepage damage. The investigation conducted a quantitative analysis of the impact of these two factors on the seepage field of the ship lock pit, considering pore pressure, water head, gradient, and flow velocity. A comprehensive set of evaluation indicators for seepage safety was formulated, drawing on the principles of multi-objective optimization, and a method for delineating the safe range of ship lock pit excavation under seepage action was proposed. Subsequently, an integrated seepage safety risk assessment system for ship lock pit excavation engineering was established. These research findings offer a scientific foundation for the management of seepage safety in ship lock pit excavation engineering and provide valuable references and guidance for the development of anti-seepage systems. [ABSTRACT FROM AUTHOR]

It is vital to analyze ship collision risk for preventing collisions and improving safety at sea. This paper takes Ningbo-Zhoushan Port, a typical complex navigable water, as the research object. Firstly, a probabilistic conflict detection method based on an AIS data-driven dynamic ship domain model is proposed to achieve effective ship conflict detection under uncertain environments. Then, a ship group identification method is proposed, which can extract the ship groups with conflict correlation and space compactness. Finally, according to the characteristics of ship traffic in complex navigable waters, the dynamic calculation of ship collision risk is carried out from individual, regional, and local multi-scale perspectives. The experimental results show that the proposed method can detect the collision risk in a timely, reliable, and effective manner under complex dynamic conditions. As such, they provide valuable insights into ship collision risk prediction and the development of risk mitigation measures. [ABSTRACT FROM AUTHOR]

Decision-making for collision avoidance in complex maritime environments is a critical technology in the field of autonomous ship navigation. However, existing collision avoidance decision algorithms still suffer from unstable strategy exploration and poor compliance with regulations. To address these issues, this paper proposes a novel autonomous ship collision avoidance algorithm, the dynamically adjusted entropy proximal policy optimization (DAE-PPO). Firstly, a reward system suitable for complex maritime encounter scenarios is established, integrating the International Regulations for Preventing Collisions at Sea (COLREGs) with collision risk assessment. Secondly, the exploration mechanism is optimized using a quadratically decreasing entropy method to effectively avoid local optima and enhance strategic performance. Finally, a simulation testing environment based on Unreal Engine 5 (UE5) was developed to conduct experiments and validate the proposed algorithm. Experimental results demonstrate that the DAE-PPO algorithm exhibits significant improvements in efficiency, success rate, and stability in collision avoidance tests. Specifically, it shows a 45% improvement in success rate per hundred collision avoidance attempts compared to the classic PPO algorithm and a reduction of 0.35 in the maximum collision risk (CR) value during individual collision avoidance tasks. [ABSTRACT FROM AUTHOR]

The oblique collision happening in vehicle accidents poses a huge threat to passive safety, which causes great difficulties in the design of energy absorption (EA) structures and the prediction of EA capacity due to its highly nonlinear deformation characteristics. This study aims to establish a theoretical prediction model for the compression performance of Carbon Fiber Reinforced Polymer (CFRP)/Al hybrid tube considering the loading angle. First, a high‐precision FE model was established to obtain the influence laws of tube diameter, Al thickness, and CFRP thickness on the crashworthiness of CFRP/Al hybrid tubes, laying the foundation for subsequent theoretical model validation. Second, by summarizing the deformation modes of hybrid tubes generated by various parameter combinations, a modified global origami deformation assumption was proposed under multi‐angle compression conditions, and the key terms in energy composition are extracted based on the initial and final states of folding elements. Third, a theoretical model for predicting the mean crushing forces (MCFs) of hybrid tubes was established by revealing the correlation mechanism between energy composition terms and loading angle. Finally, the theoretical prediction model was validated by experiment and simulation results and the application premise was given. Results showed that the theoretical prediction model was proved to be of high accuracy, as the average absolute prediction errors of MCF under axial, 10°, 20°, and 30° compression conditions were 6.54%, 4.63%, 3.72%, and 3.93%, respectively. This study provides valuable guidance for the forward design and development of multi‐material hybrid structures facing complex crushing conditions. Highlights: An analytical model of the hybrid circular tubes considering compression angle is newly proposed.Deformation mode and axial crushing response are analyzed by experiments.The major energy dissipation mechanism for hybrid circular tubes is explicitly derived.The Al thickness has the most significant impact on energy absorption.The recommendations for the design and development of hybrid tube are provided. [ABSTRACT FROM AUTHOR]