Search

Decarbonization has significant operational implications for ships, fuel resources, and ports. Sustainable management is highly prioritized by ship owners and port authorities. The shipping industry must develop appropriate strategies to achieve zero carbon emissions by 2050 and support the 2030 United Nations sustainable development goals. Tugboats, a ubiquitous vessel in Taiwanese ports, were selected as the subject of this study. Implementing hybrid power systems in response to the growing trend of carbon reduction was explored. This study involves various stakeholders in Taiwan, including ship owners, port agency representatives, and other relevant parties. Assessing investment costs, market demand, and policy guidance is highly significant. Establishing a positive cycle is necessary to encourage tugboat operators to adhere to sustainable management practices and environmental protection measures. This entails providing incentives through policy measures that enable tugboat operators to gain cost advantages and balance environmental, economic, and societal needs within an expanding market. [ABSTRACT FROM AUTHOR]

This paper simulated a simultaneous un-berthing of two container ships. The simulation was intended to determine the number and capacity of tugboats considering an emergency situation in a port. A port provides the number and capacity of tugboats based on the regulation of the Transportation Ministry. In an emergency condition at the terminal and the maximum environmental conditions of wind, wave, and current, the vessel should be un-berthed simultaneously. In this study, two container ships are un-berthed simultaneously in eight scenarios. The available tugboats are simulated using the MMG model to pull the vessels from the jetty turn them in the approaching channel and pass the main channel to achieve the anchorage area. The trajectories of maneuvering using the existing tugs are compared to the normal passage using the appropriate capacity of tugboats. The number and capacity of the tugboat to comply with the safety criteria and avoid collision between the un-berthed ships is proposed. [ABSTRACT FROM AUTHOR]

Influenced by the dynamics of supply and demand, the demand for maritime transport has been increasing annually, putting significant pressure on container ports. To alleviate this pressure, a new mixed-integer programming model for the integrated scheduling of tugboats, berths, and quay cranes has been established. This model considers the uncertainties in vessel arrival times, vessel berthing preferences, time-varying quay crane availability, and the constraint that quay cranes cannot cross each other. The objective is to minimize the total costs including fuel consumption during port stays, delays and waiting times for berthing and departure, berthing deviation costs, tugboat assistance costs, and quay crane handling costs. To obtain high-quality solutions, an adaptive large neighborhood search (ALNS) algorithm was employed to solve the model. The algorithm incorporated five destruction operators and five repair operators that were specifically designed to enhance the solution accuracy and efficiency for the integrated scheduling problem. Several case studies of varying scales, based on a port in China, were used to validate the effectiveness of the proposed model and algorithm. The experimental results demonstrate the model's validity and show that the ALNS algorithm designed for the integrated scheduling problem outperformed CPLEX and other algorithms in terms of the accuracy and efficiency. Finally, a sensitivity analysis of the key parameters provides recommendations for the integrated scheduling of tugboats, berths, and quay cranes, offering valuable insights for port operations. [ABSTRACT FROM AUTHOR]

Ship maneuvering in ports is increasingly reduced because the increase in ship size is not proportional to the increase in port areas. Furthermore, the number of assisted vessels and the need for tugboats working in densely populated areas make it necessary to reduce the number of involved tugboats, reducing pollution and costs. Therefore, shiphandlers must know, in addition to the pivot point, the center of lateral resistance under any circumstance to optimize the assistance from tugboats and improve maritime navigation. From the literature, it is evident that the practical determination of the center of lateral resistance is still unknown. This paper aims to propose novel mathematical models to identify the position of this point and the most important variables that determine its position. For that, data of different ships in different conditions were obtained from a full mission bridge simulator. Afterwards, 15 novel mathematical models were developed, making use of artificial intelligence tools and training neural networks. The high determination factor reached in some models shows the accuracy of the obtained models. One advantage of the presented models is that they are very easy to be applied by shiphandlers, because highly well-known parameters are involved. Moreover, original 3D charts showing the combination of the input variables were generated to identify the map of the whole process. The very simple new models obtained and the novel 3D charts shown in the present paper can be considered useful and applicable by the shiphandlers of most of the merchant fleet to improve the efficiency and safety of maritime navigation in increasingly restricted waters. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of tugboat services and ship document readiness on the productivity of the MT Akra 102 Ship Agency, which is represented by PT Transuta Lintas Samudera, Merak Branch. PT. Transuta Lintas Samudera is a shipping company engaged in shipping agency services for domestic and foreign ships in the Merak Port area. There are several problems with delays in the berthing of foreign ships that occurred at the Port of Banten. An example is the ship MT. AKRA 102 which is routinely agented every time it comes to the Merak Port area. PT Transuta Lintas Samudera, Merak Branch is one of the companies engaged in ship agency services. There is a phenomenon of non-fulfillment of MT ship productivity targets. AKRA 102 expected by the company with what happened in the field. Especially in June, August, October and December in 2021 and in May and June in 2022 which was caused by delays in pilot tugboat services and readiness of ship documents. This can affect consumer confidence in agency companies which can lead to reduced company income. The approach method used in this study uses a quantitative approach. The target population in this study were ship agents, ship owners, jetty masters and company employees with a sample of 45 respondents. The sampling technique in this study uses saturated samples, research uses quantitative data types. Quantitative data obtained from this study is data from the results of respondents' answers presented in the form of a Likert scale. Data collection techniques by distributing questionnaires or questionnaires directly to respondents. The data statistical method used is descriptive statistics and SPSS version 25.0. [ABSTRACT FROM AUTHOR]

This article investigates the vibration analysis of the mast on the bridge top of a 28 m tugboat, in the quasi-static regime. The study aims to determine the natural frequencies using an equivalent dynamic model of the mast and considers the accelerations of different degrees of freedom of the vessel. Practical design and reinforcement strategies for the local bridge top structure are proposed, utilizing numerical and analytical tools. The investigation explores various alternatives to optimize the structural arrangement. By analyzing the modal behavior, insights are provided for efficient design and reinforcement. The results contribute to understanding the mast's vibration characteristics, offering guidance for similar structures. This study employs numerical and analytical methods, enhancing the optimization of the mast's behavior. It determines natural frequencies, proposes practical design strategies, and explores alternatives for structural optimization. The findings provide insights for shipbuilding and mast design applications in other vessels and industries such as radar mast, compass deck, and guyed mast. [ABSTRACT FROM AUTHOR]

In response to challenges such as narrow visibility for ship navigators, limited field of view from a single camera, and complex maritime environments, this study proposes panoramic visual perception-assisted navigation technology. The approach includes introducing a region-of-interest search method based on SSIM and an elliptical weighted fusion method, culminating in the development of the ship panoramic visual stitching algorithm SSIM-EW. Additionally, the YOLOv8s model is improved by increasing the size of the detection head, introducing GhostNet, and replacing the regression loss function with the WIoU loss function, and a perception model yolov8-SGW for sea target detection is proposed. The experimental results demonstrate that the SSIM-EW algorithm achieves the highest PSNR indicator of 25.736, which can effectively reduce the stitching traces and significantly improve the stitching quality of panoramic images. Compared to the baseline model, the YOLOv8-SGW model shows improvements in the P, R, and mAP50 of 1.5%, 4.3%, and 2.3%, respectively, its mAP50 is significantly higher than that of other target detection models, and the detection ability of small targets at sea has been significantly improved. Implementing these algorithms in tugboat operations at ports enhances the fields of view of navigators, allowing for the identification of targets missed by AISs and radar systems, thus ensuring operational safety and advancing the level of vessel intelligence. [ABSTRACT FROM AUTHOR]

Determining the key characteristics of a ship during the concept and preliminary design phases is a critical and intricate process. In this study, we propose an alternative to traditional empirical methods by introducing a model to estimate the main particulars of diesel-powered Z-Drive harbor tugboats. This prediction is performed to determine the main particulars of tugboats: length, beam, draft, and power concerning the required service speed and bollard pull values, employing Bayesian network and non-linear regression methods. We utilized a dataset comprising 476 samples from 68 distinct diesel-powered Z-Drive harbor tugboat series to construct this model. The case study results demonstrate that the established model accurately predicts the main parameters of a tugboat with the obtained average of mean absolute percentage error values; 6.574% for the Bayesian network and 5.795%, 9.955% for non-linear regression methods. This model, therefore, proves to be a practical and valuable tool for ship designers in determining the main particulars of ships during the concept design stage by reducing revision return possibilities in further stages of ship design. [ABSTRACT FROM AUTHOR]

This study investigates the automated transportation control problem of an offshore floating platform that has limited or no maneuverability. The proposed solution involves two tugboats pushing into the platform and two other tugs towing it in the opposite direction. By implementing cooperative control of these tugs, the desired planar motion of the platform is achieved. For this, the proposed control consists of the following components: (1) an observer estimates the environmental disturbances, (2) a platform motion controller acts as the supervisory control, (3) an optimal constrained allocation distributes the required actions over the tugboats, and (4) the tugboats' controller derived the control inputs of the tugs to fulfill these requirements. Simulation studies are conducted where the proposed solution is compared to one based on the robust H∞ control framework. The results prove the efficiency and robustness of the proposed system. [ABSTRACT FROM AUTHOR]

With the continuous prosperity of maritime transportation on a global scale and the resulting escalation in port trade volume, tugboats assume a pivotal role as essential auxiliary tools influencing the ingress and egress of vessels into and out of ports. As a result, the optimization of port tug scheduling becomes of paramount importance, as it contributes to the heightened efficiency of ship movements, cost savings in port operations, and the promotion of sustainable development within the realm of maritime transportation. However, a majority of current tugboat scheduling models tend to focus solely on the maximum operational time. Alternatively, the formulated objective functions often deviate from real-world scenarios. Furthermore, prevailing scheduling methods exhibit shortcomings, including inadequate solution accuracy and incompatibility with integer programming. Consequently, this paper introduces a novel multi-objective tugboat scheduling model to align more effectively with practical considerations. We propose a novel optimization algorithm, the Improved Grey Wolf Optimization (IGWO), for solving the tugboat scheduling model. The algorithm enhances convergence performance by optimizing convergence parameters and individual updates, making it particularly suited for solving integer programming problems. The experimental session designs several scale instances according to the reality of the port, carries out simulation experiments comparing several groups of intelligent algorithms, verifies the effectiveness of IGWO, and verifies it in the comprehensive port area of Huanghua Port to get the optimal scheduling scheme of this port area, and finally gives management suggestions to reduce the cost of tugboat operation through sensitivity analysis. [ABSTRACT FROM AUTHOR]

Effective utilization of tugboats is the key to safe and efficient transport and service in ports. With the growth of maritime traffic, more and more large seaports show a trend toward becoming super-scale, and are divided into multiple specialized terminals. This paper focuses on the problem of large-scale tugboat scheduling. An optimization problem is formulated considering the cross-region constraints and uncertainties during tugboat operation. An improved genetic algorithm is proposed based on the reversal operation (GA-RE) to solve the formulated Tug-SP. A task-triggered strategy is designed for dynamic scheduling and dealing with uncertainties. Taking Zhoushan Port as a representation of multi-terminal seaports, simulation experiments are carried out to demonstrate the effectiveness of the proposed method. Compared with historical scheduling data and the standard GA, the proposed method shows good performance in solving different scale instances (including a large-scale instance of 191 ships) in terms of solution quality and computational time. [ABSTRACT FROM AUTHOR]

In the face of developments in maritime transportation due to globalization, ports are tending toward new tugboat investments in order to respond to the increasing demand. Due to the high costs of tugboats, organizations may face high investment costs. It is important to determine the most suitable number of tugboats, considering the variables in a port area where towage services will be provided. In this study, a simulation model was developed to determine sufficient tugboat allocation according to some variables in ports. The simulation model was subjected to various experiments, and statistical analyses of the obtained results were performed. The relationships between the variables affecting the level of towage service were revealed. [ABSTRACT FROM AUTHOR]

This study proposes a novel fuzzy programming optimization model for tugboat scheduling, directly considering multiple berthing bases, time windows, and operational uncertainties. The uncertainties in the required number of tugboats, the earliest start time, the latest start time, the processing time, and the start and end locations of each task are directly captured in the proposed fuzzy optimization model. The objective of the presented formulation is to minimize the total cost of fuel and delays. According to the characteristics of the problem, a Grey Wolf Optimization algorithm based on random probability encoding and custom genetic operators is proposed. The proposed algorithm, LINGO, the canonical Grey Wolf Optimization algorithm, and particle swarm optimization were used to compare and analyze the results of several examples. The results validate the efficiency of the proposed algorithm against the alternative exact and metaheuristics methods. Moreover, the findings from the conducted sensitivity analysis show the applicability of the developed fuzzy programming model for different confidence interval levels. [ABSTRACT FROM AUTHOR]

This paper discusses the path-following control of a ship or other floating object by pushing using a single autonomous tugboat. To do this, we first formulate a reduced dynamic equation that contains the dynamics of both the ship and the tugboat without contact force terms, and is expressed by independent variables, such as ship variables (surge, sway, and yaw rates), allowing us to deal with the ship and tugboat as a single system to control the independent variables. It is assumed in this study that the contact between the ship and tugboat is a point contact, and the contact point does not slip. To manipulate the motion of a ship by pushing, the pushing force must be exerted without slipping at the contact point. Thus, the contact force is derived from the dynamic equations of the ship and tugboat and the velocity constraints on the contact point, and its feasible region is defined. This contact force condition is then incorporated into a path-following control method using the reduced dynamic equation to handle the contact force during the pushing operation. The contact force is checked to determine whether it is likely to be exerted outside the feasible region; if so, the control gain used in the path-following control is switched to a smaller value. Simulations under different paths and contact positions are performed, and the results demonstrate that the proposed pushing control method allows the ship to follow a given path correctly while maintaining the contact condition. [ABSTRACT FROM AUTHOR]

The use of hybrid energy systems in ships has increased in recent years due to environmental concerns and rising fuel prices. This paper focuses on the development and study of a hybrid energy system using liquefied natural gas (LNG) and batteries for a tugboat. The hybrid system model is created in MATLAB/Simulink® and uses fuel data obtained from an operational diesel-powered tugboat. The LNG–hybrid system is then subjected to testing in four distinct configurations: fixed speed, variable speed, and with and without a battery. The different configurations are compared by computing the daily fuel cost, CO2 emissions, energy efficiency operation indicator ( E E O I ) and carbon intensity indicator ( C I I ) ratings in three distinct operation cases. The analysis reveals that the use of an LNG–battery hybrid tugboat results in an average reduction of 67.2% in CO2 emissions and an average decrease of 64.0% in daily fuel cost compared to a diesel system. An energy management system using rule-based (RB) control is incorporated to compare the daily cost and CO2 emissions for one of the case studies. The rule-based control that requires the battery to be used and the LNG engine to be switched off at the lowest allowable minimum power based on the specific gas consumption produces the most cost-effective control strategy out of all the different control strategies tested. The result demonstrates that an additional reduction of CO2 and daily fuel cost for LNG–battery hybrid tugboats by 23.8% and 22.3%, respectively, could be achieved with the implementation of the cost-effective strategy as compared to not having a control strategy. [ABSTRACT FROM AUTHOR]

This study investigates the cognitive levels of tugboat captains, key players during port manoeuvres, which are a crucial part of sea navigation. The objective is to reveal the main neurophysiological findings related to the measurements of the tugboat captains' brain activity during both rest and actual manoeuvring performance and to investigate the relationship between this brain activity and situational awareness. The study employed an experimental research method. Brain waves of the tugboat captains were recorded using the Emotiv X EEG device and the Emotiv Pro v2.0 program during real port manoeuvres which is a part of the sea navigation. Situational awareness levels were tried to be determined by analysing the obtained values in the Brain Products Vision Analyzer 2.1 software. The study examined the cognitive states of four tugboat captains during 16 manoeuvres and resting, focusing on the Fast Fourier Transform (FFT)/Band power graph values. Within the scope of the research non-parametric Friedman Test with five variables [Resting State (RS), 1st Manoeuvre Group, 2nd Manoeuvre Group, 3rd Manoeuvre Group, and 4th Manoeuvre Group] to analyse the FFT values of the participants. Post-hoc comparisons were calculated using Bonferroni correction. The results showed no difference in alpha wave power, while delta, theta, beta, and gamma power decreased. The primary outcome of the research indicates that professional tugboat captains, who were the participants of the study, exhibited consistent situational awareness levels both during manoeuvring and resting moments. [ABSTRACT FROM AUTHOR]

Tugboat service is important for maintaining the safety and efficiency of ship movements in container ports. In practice, requests for tugboat service are not fully known when the planning horizon begins, but continually revealed while the existing tugboat scheduling is being performed. Thus, a tangible method is required to schedule tugboats to fulfill the continually arrived requests. However, there is no study on addressing this issue. Thus, we propose a dynamic tugboat scheduling problem, formulate the problem mathematically, and develop a tailored solution method that dynamically updates tugboat scheduling as new service requests arrive, so as to minimize the tugboat operation cost of whole planning horizon. We evaluate the effectiveness of the proposed solution method by comparing it with a benchmark method, and show that the solution method is able to achieve satisfactory performance within a reasonable computation time. In addition, we investigate managerial insights via computational experiments on a variety of instances created based on real-life container port operations. [ABSTRACT FROM AUTHOR]

Autonomous ship technology, which includes real-time monitoring, satellite communication, and automatic navigation, is rapidly advancing. Despite significant research on single unmanned ships, there is a lack of studies on complex tasks, such as ship berthing using a swarm of autonomous tugboats. This review article provides an overview of various projects related to autonomous tugboats for ship berthing and discusses the research trends in the required technologies, including recognition, decision making, modeling, and control. We identify the areas that have been underexplored in existing studies and suggest future research directions to advance the field. Overall, this review contributes to a better understanding of the challenges and opportunities for the development of autonomous tugboats for ship berthing. [ABSTRACT FROM AUTHOR]

Assisting harbour tugboats are essential for safe navigation in ports and for berthing/unberthing operations. Because the port infrastructure needs to be updated in the coming age of autonomous ships, autonomous tugboats or remotely controlled tugboats are expected to be part of the navigation assistance provided by future ports. Although there have been some studies on the design of cooperative control of tugboats, few studies have focused on the mathematical model of their cooperative manoeuvres. Particularly, in the case of pushing assistance, tugboats have often been treated simply as a kind of side thrusters attached to the assisted ship. Thus, we present a new framework of the mathematical model for cooperative manoeuvres that considers the coupled motions among tugboats and a ship as precisely as possible. Solving the dynamics of all tugboats as well as the assisted ship can render the model more advanced and realistic, and is the most significant contribution of this study. The simulation tool based on the proposed model can be used as a plant model in designing and verifying the tugboat's manoeuvring control system in the future. In this study, as examples, considering a tentative control method, some unique scenarios were simulated to demonstrate the cooperative manoeuvres. [ABSTRACT FROM AUTHOR]

The configuration of marine towing cable changes significantly during the turning process, with the rotating procedure with fixed cable length being the most frequent. To overcome these challenges, the configuration and dynamic properties of the marine towing cable must be addressed. However, under some particular operating situations, the tugboat must release the marine towed cable during rotation, resulting in a constant change in the length of the marine cable. In view of this, the towed cable is discretized into a lumped mass model based on the lumped mass method, and the dynamic analysis model of the rotation process of towed cable with variable length under different release speeds and different depths is established. This is done with reference to the specific parameters of a towed system, combined with the specific sea conditions of a particular sea area. Time-domain coupling analysis is used to determine the dynamic changes in configuration and stress of marine towing cable at various release speeds and depths. The results of the calculations have some guiding relevance for a certain engineering practice. [ABSTRACT FROM AUTHOR]

Microbiologically influenced corrosion (MIC) has a significant cost to many industries, including naval engineering. In this case-of-study, three tugboats developed pitting corrosion in the carbon steel of the inner hulls. Grade A naval steel was used for the hull sheets but the inner side (corroded) showed only two protective layers of paint. The maintenance employed seawater, which ended up in the bilge and made MIC possible. Bilge's waters were submitted to physicochemical, biological and molecular tests. DNA analyses confirmed the presence of Pseudomonas spp. and Desulfovibrio spp. in water samples and, consequently, a MIC mechanism was proposed to explain the corrosion process. In addition, a biocide treatment was evaluated and a new maintenance protocol was recommended. This work highlights the importance of the engineering design to prevent MIC in marine transports and provides some guidelines to treat it. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology 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 topic of reducing exhaust gas emissions from internal combustion engines in the areas of port and coastal waters is in line with the assumptions of the climate policy. The publication presents a proposal to reduce the energy associated with the movement of port vessels through the use of a specific pattern (shape and size) of their movement. In addition to controlling the formation of tugboats, the authors propose the use of a multi-agent system offering elements of autonomous control of the vessels, which adjusts the parameters of the formation depending on the tasks performed. The results of tests for four tugboats with a hull length of 32 m and a maximum speed of 13 knots, moving in formations of eight different configurations, were analyzed. Studies conducted on the basis of a simulated exit and return to port scenario at a distance of 11.4 nm showed the possibility of reducing energy consumption required for movement by 5.8% to even 57.6% for tugboats moving one after another, at a certain distance. In addition, in order to completely eliminate exhaust gas emissions from the engines, it is proposed to use tugboats with electric drive together with an appropriate energy storage charging infrastructure. [ABSTRACT FROM AUTHOR]

In order to study the construction technology applicable to the floating transportation of immersed tubes in the Dalian Bay Subsea Tunnel, combined with the meteorological and hydrological conditions of the Dalian Bay and the channel characteristics of the floating, the towing effect of different tugboat combinations under different conditions was tested through the immersed tube floating drills. Based on the test data and effect analysis of floating drift, base groove steading ship, steering operation and emergency disposal, the optimal towing technology of immersed tube for Dalian Bay Subsea Tunnel was established. This technology has been successfully applied in the floating construction of 18 immersed tubes in the Dalian Bay Subsea Tunnel, effectively controlling the average drift value of immersed tubes’ floating transportation to be less than 5 m, and the maximum drift value to be less than 25 m, which greatly improves the technical and economic benefits of immersed tubes floating transportation and ensures the controllable safety risk. [ABSTRACT FROM AUTHOR]

At present, the sensitivity of society towards emissions in commercial maritime ports is increasing, which is reflected in the large number of studies on the control of emissions in them, perhaps because the most important commercial ports are located in cities with high population density. The objective of this work was to determine the greenhouse gas emissions caused by the activity of the Spanish tugboat fleet, studying the tugboat fleet of the eleven autonomous coastal Spanish communities from 2004 to 2017 and their impact on the carbon footprint of the country's shipping sector. To do this, the methodology used by the International Maritime Organization for merchant ships to estimate the emissions of a tugboat fleet is formalized, and Gini concentration index methodology was applied to the concentration of emissions from this fleet. This has made it possible to obtain results on the distribution of the concentration of emissions from Spanish ports by region, age, and size, as well as to establish the profile of the tugboat port that pollutes the most and its carbon footprint. One of the results is that in the period analyzed, the concentration of emissions from the Spanish tugboat fleet increased if we looked at its distribution by region, and decreased if we look at its distribution by age and size. This is because tugboat activity was very different by region; however, their characteristics related to age and size evolved in a more homogeneous way. [ABSTRACT FROM AUTHOR]

The operating conditions of all-electric tugboats are flexible and changeable. They are more complicated than conventional vessels in terms of joint voyages and power generation scheduling. To guarantee the reliable operation of the ship, a new coordinated optimization scheme that combines economy and operational reliability is proposed. It is based on the various operating conditions of the tugboat during its voyage, taking into account the random outages of equipment and load fluctuations due to speed and wave uncertainties. Due to the difficulty of implementing a stochastic sampling method with space-time coupling constraints (e.g., the voyage is related to propulsion load), an analytical approach is needed to transform the model into a readily solvable mixed-integer linear program (MINP) which attributes risk scenarios to load fluctuations under various conditional probabilities. In addition, this paper proposes an improved piecewise linearization method based on a differential evolutionary algorithm to speed up the solution process and improve computational accuracy. Meanwhile, the energy storage loss cost due to battery degradation is added to the optimization target. The battery's cycle life is extended by rational scheduling of charging and discharging. Simulations validate this paper's joint scheduling optimization scheme in multiple comparison experiments. The results show that it can effectively balance the economic and reliability levels under various risk scenarios and improve the environmental energy efficiency indicators. [ABSTRACT FROM AUTHOR]

The recent surge in fuel costs and stringent gas emission regulations mandated by the International Maritime Organization (IMO) has prompted research into integrating renewable energy and energy management strategies (EMS) onboard ships. This study illustrates the computation, simulation, and optimization of a hybrid renewable energy system (HRES) to ensure continuous power supply for auxiliary loads and critical systems on both conventional and fully autonomous tugboats. The primary aim is to design an optimal HRES with minimal annualized cost of system (ACS) and a higher proportion of renewable energy while using an artificial bee colony (ABC) algorithm. Validation of optimization outcomes is conducted using particle swarm optimization (PSO), genetic algorithm (GA), and Hybrid Optimization of Multiple Energy Resources (HOMER) Pro. The HRES incorporates diesel generators (Gensets), photovoltaic (PV) arrays, vertical axis wind turbines (VAWT), and battery banks. The optimal HRES configuration for both conventional and fully autonomous tugboats is found to be Genset/PV/VAWT/Battery. We observe that the ABC algorithm exhibits superior convergence, reliability, cost-effectiveness, renewable energy fraction, and reduced carbon emissions compared to alternative algorithms. Results of robustness tests suggest that the shipload variation, fuel prices, temperature fluctuations, wind speed and solar irradiance along the navigation route have significant impact on the optimal HRES configuration. Ultimately, we conclude that the fully autonomous tugboat demonstrates superior performance in terms of costs, carbon dioxide emissions, and renewable energy fraction compared to its conventional counterpart. • Optimization of a HRES aboard both traditional and fully autonomous tugboats is conducted. • A comparative study of three metaheuristic algorithms is undertaken to determine the optimal HRES configuration. • ABC emerges as the most effective algorithm for allocating the optimal HRES setup. • The proposed energy management strategy efficiently reduces carbon dioxide emissions, dump energy, and the annualized cost of the system. • Sensitivity analysis and Post Ad hoc test are performed on the optimal HRES and the metaheuristic algorithms. [ABSTRACT FROM AUTHOR]

In this paper, through the continuous analysis of the engine oil of a 2600HP tugboat in 4 years, the detection data of spectrum, viscosity, moisture, degree of vulcanisation, pH, fuel dilution, flash point, and oxidation degree are obtained. The variable of these parameters over time is discussed. Nothing abnormal wear is found in the main friction parts of the engine. Lubricating oil is seriously vulcanised and acidification, which affects the oxidation degree. The performance of oxidation, sulphisation, PH, and fuel dilution is seriously degraded. The coupling effects of water content, acid value, alkali value, vulcanisation degree, and mechanical impurity should be considered in determining the oxidation and ageing of lubricating oil. It should be noted that excessive loss of alkaline additives in tugboat operation. The results provide an effective reference basis and experience guidance for better judging the wear state of the friction pair and condition-based maintenance based on lubricating oil. [ABSTRACT FROM AUTHOR]

Barge ships are designed to transport and assemble heavy and massive pieces of equipment at sea. Active propulsion systems are not installed in this type of ship, so the desirable motion and positioning of these ships can only be achieved with the assistance of several tugboats. In this study, the dynamical characteristics of barge conveying systems were formulated and robust control systems were designed to ensure efficient barge operation. To achieve these objectives, we first developed a mathematical model of a barge ship, which incorporated a novel conveying system configuration using tugboats. We then designed a robust controller for the tugboats that used the sliding mode law to deliver the desired barge motion performance. Finally, the usefulness of the proposed configuration and controller was verified via simulation studies using another system with an H ∞ controller. The proposed sliding mode controller showed superiority, especially in terms of robustness against disturbances. [ABSTRACT FROM AUTHOR]

This study proposes a hybrid Solar PV/Wind backup solution for a marine tugboat. Tugs are an important kind of vessel that should be able to maneuver continuously without any interruption of their electrical energy system. New power management integrating a hybrid solar/wind energy aims to ensure a long period of continuous safe operation in case of a total blackout and also to replace the perturbed power grid of the port for a partial time. These standard tugs built in Holland by DAMEN shipyard and attached to Arzew port in Algeria, are suited to operate for a maximum of 1 hour with a storage battery unit in an emergency situation like a blackout. The two main diesel engines are able to operate normally with 24 V DC voltage control under such situations. During this problem of power failure, the tug can't reach safely the harbor and hence immediate assistance is needed. To avoid this scenario, the idea is why not extend this period of emergency operation, and also try to supply the vessel inside the port only with clean energy. First, the electrical distribution system is presented and detailed including the power demand study of installed loads. The proposed hybrid energy source is also discussed for its many benefits especially in the case of favorable maritime climatic conditions of the Arzew port area. HOMER software is used to verify if the new power scheme can succeed. The results confirm that the new combined Diesel/PV/Wind solution appears to be very interesting, it reduces CO2 emissions from diesel generators and annual fuel costs can be saved. [ABSTRACT FROM AUTHOR]

The Strait of Istanbul, 17 nautical miles long, is one of the main routes of international maritime trade. Connecting the Black Sea countries with other countries of the world, the Strait is the second busiest waterway in the world in terms of international ship traffic. In addition to busy sea traffic, limited geographical conditions also make it difficult to navigational safety. The Strait of Istanbul is the only chokepoint that stands out with the risk of maritime accidents on the primary routes of world maritime trade. This situation poses a risk for both the transiting ships and the city of Istanbul, which has a dense population around it. Some of the accidents that took place in the recent history have caused worldwide concern due to the environmental pollution they cause. Considering the advantages provided by the developing shipbuilding technology and today load capacity of the ships, a disaster that will occur in a possible accident today will cause much greater destruction than in the past. In this direction, it has become a necessity to examine the accident profile in the strait in order to develop effective accident prevention measures and to strengthen the level of navigational safety in the region. In this study, maritime accidents that occurred in the Strait of Istanbul over a 16-year period were discussed in terms of their types and the response time of tugboats to a possible accident was examined. [ABSTRACT FROM AUTHOR]

Have you ever built a spaceship using Magna-Tiles with a 4-year-old child? If not, place this on the top of your to-do list, as there are many lessons hidden within these colorful pieces of plastic. In addition to teaching patience and cooperation, the process of building with a preschooler with big emotions and an underdeveloped prefrontal cortex offers endless opportunities to serve as both a safe haven and a secure base. As each tile is carefully (or not so carefully) placed, you are building more than just a misshapen spaceship; you are reinforcing a foundation of trust and mutual respect. In helping my own 4-year-old daughter build a unicorn-themed spaceship that resembled a tug boat, I cringed when she placed the final tile that would collapse our creative masterpiece. Much to my surprise, instead of disappointment and tears, she erupted into laughter and began the process of building all over again. She reminded me that joy can come from an experience rather than an outcome, that creativity and imagination should be sprinkled daily into the work we do, and that not every spaceship is destined to be out of this world! [ABSTRACT FROM AUTHOR]

Total emissions from all sources need to be accurately quantified in an emission inventory in order for a basin to develop their air pollution management plan. The best approach is to measure both the real-world emissions and activity for a source; however, often only emissions are measured and activity is estimated from historical factors. This report focuses on harbor craft and presents data showing that using measured emissions and historical factors for activity will lead to inaccurate emission contributions. In this research, real-world activity data were collected from the engine control module (ECM) and from a surrogate method that relied on exhaust temperature. Measured real-world activity values from 10 harbor craft were compared with historical values found in the certification cycle. The vessels included four tugboats, three pilot boats, two police boats, and one supply vessel. The results showed the activity values used in the certification cycle did not reflect the real-world activity of the 10 harbor craft vessels. On average, real-world NOx emissions were only 46% of the NOx emissions estimated by ISO 8178-E3 weighting factor. In contrast, inclusion of significantly lower load factors leads to 31% higher in-use NOx emission factors on average. CARB/EPA load factor ranges from 0.45 to 0.51 while in-use load factor ranged from 0.14 to 0.44. From this finding, researchers are cautioned about accepting the activity values in a certification test cycle, like ISO 8178 E3, and instead should measure real world activity data. This change would improve the accuracy of the emission contribution from harbor craft to the local inventory. Implications: Real-world measurements of activity and emissions are the best way to get an accurate emission contribution to emission inventory. This paper reports on the differences between the use of the traditional certification cycle and real-world activity of harbor craft. Engine control module (ECM) and exhaust temperature data from 10 harbor crafts with different types of operation were used to compare real-world activity data to certification cycle. [ABSTRACT FROM AUTHOR]

Changing and often class-dependent non-stationarities of signals are a big challenge in the transfer of common findings in cognitive workload estimation using Electroencephalography (EEG) from laboratory experiments to realistic scenarios or other experiments. Additionally, it often remains an open question whether actual cognitive workload reflected by brain signals was the main contribution to the estimation or discriminative and class-dependent muscle and eye activity, which can be secondary effects of changing workload levels. Within this study, we investigated a novel approach to spatial filtering based on beamforming adapted to changing settings. We compare it to no spatial filtering and Common Spatial Patterns (CSP). We used a realistic maneuvering task, as well as an auditory n-back secondary task on a tugboat simulator as two different conditions to induce workload changes on professional tugboat captains. Apart from the typical within condition classification, we investigated the ability of the different classification methods to transfer between the n-back condition and the maneuvering task. The results show a clear advantage of the proposed approach over the others in the challenging transfer setting. While no filtering leads to lowest within-condition normalized classification loss on average in two scenarios (22 and 10%), our approach using adaptive beamforming (30 and 18%) performs comparably to CSP (33 and 15%). Importantly, in the transfer from one to another setting, no filtering and CSP lead to performance around chance level (45 to 53%), while our approach in contrast is the only one capable of classifying in all other scenarios (34 and 35%) with a significant difference from chance level. The changing signal composition over the scenarios leads to a need to adapt the spatial filtering in order to be transferable. With our approach, the transfer is successful due to filtering being optimized for the extraction of neural components and additional investigation of their scalp patterns revealed mainly neural origin. Interesting findings are that rather the patterns slightly change between conditions. We conclude that the approaches with low normalized loss depend on eye and muscle activity which is successful for classification within conditions, but fail in the classifier transfer since eye and muscle contributions are highly condition-specific. [ABSTRACT FROM AUTHOR]

Tugboat operations present a high degree of risk and to prevent accidents, the crew must know and manage very well all the necessary maneuvers. Stability is a critical aspect for the safety of tugboats and towing operations, so recently new international regulations have been developed. The tugboats perform several functions, the main one being pulling, but by being equipped with certain equipment and installations, the tugboats are intended for rescue, firefighting, depollution, ice breaking and occasional transport. For this study, two categories of tugboats were considered to determine the geometric characteristics, hydrostatic, of stability and longitudinal strength. The Modelmaker module is used to create the ship's body (Geometry File), the superstructure and all appendages, after which the compartmentation is created and the types of compartments and tanks are positioned in the ship's body. To determine the safety of the two tugboats from the point of view of stability, the heeling moment (the heeling arm) that occurs during towing with the righting arm was checked. At the end, the safety status of the two categories of tugboats was analyzed and new projects were proposed for the future, regarding the use of stability criteria for tugboats. [ABSTRACT FROM AUTHOR]

The publication presents the structure of the agent system, tasked with control of the formation of unmanned port tugboats capable of performing pilot and towing services. The use of autonomous tugboats with installed software was presented with respect to the existing regulations related to Resolution MSC.467 developed by the Maritime Safety Committee (MSC) belonging to the International Maritime Organization (IMO), which creates guidelines for the definition and harmonization of the structure and format of maritime services in the context of e-navigation. The use of a multi-agent system structure enables synergistic cooperation of tugboats carrying out joint port operations, such as: assistance in maneuvers of ships, precision movement of ships and other objects in port areas, monitoring and patrolling of port areas, carrying out ice operations, carrying out inspections of quays, the possibility of assistance in liquidation of petroleum and similar pollutant spills. The paper presents the structure of the agent system and the description of possible scenarios of port operations. The control algorithms and the applied methods of artificial intelligence, such as evolutionary algorithms with elements of fuzzy logic, were discussed. The recorded traffic parameters from the actions carried out in the simulator of the marine navigation environment were presented. [ABSTRACT FROM AUTHOR]

In a seaport, vessels need the assistance of tugboats when mooring and unmooring. Tugboats assist a vessel by pushing or towing the vessel's tug points, and the vessel can moor (or unmoor) successfully only if each of the tug points is operated with sufficient horsepower. For a busy port where vessels frequently require the service of tugboats, effectively scheduling tugboats for serving incoming and outgoing vessels is a key to successful execution of the vessels' berth plans. In this paper, we study a tugboat scheduling problem in a busy port, where incoming and outgoing vessels frequently require the assistance of tugboats, but the number of available tugboats is limited. We make use of a network representation of the problem and develop an integer programming formulation, which takes into account the berth plans of vessels, the tug points of vessels for different move types, and the horsepower requirements of the tug points, to minimize the weighted sum of the berthing and departure tardiness of vessels, the operating cost of tugboats, and the number of vessels that cannot be served successfully. We analyze the computational complexity of the problem and develop a novel iterative solution method, which combines Lagrangian relaxation and Benders decomposition, for generating near-optimal solutions. Computational performance of the proposed solution method is evaluated on problem instances generated from the operational data of a container port in Shanghai. [ABSTRACT FROM AUTHOR]

The telegraph controller is a device used to control the speed of a ship, and it is a device that has a very direct effect on the safety of the crew. Accordingly, ship owners demand very high reliability of the telegraph controller, and the classification trend is to introduce HILS (hardware in loop system) test as a method to verify reliability. Therefore, in this paper, an electric propulsion ship was modeled to perform the HILS test of the Telegraph controller. For modeling, the specifications of the electric propulsion tug boat were defined, and the battery parts, propulsion motor parts, and ship model parts were modeled. In addition, various operation scenarios were defined and the Telegraph controller was modeled accordingly. Finally, the results of the integrated model were confirmed through simulation. [ABSTRACT FROM AUTHOR]

The Strait of Istanbul, which connects the Black Sea countries and the rest of the world, is the second busiest waterway in the world. In addition to intensive maritime traffic, the increased risk of accidents is alarming, given the environmental factors that complicate the navigation of the vessels. Historical data and literature review have shown that there is room for improvement with regard to measures taken to ensure the safe navigation in order to prevent accidents in the Strait of Istanbul. In this respect, determining the characteristics of past maritime accidents and identifying risky areas is vital to improve the level of safety. In this study, the temporal and spatial profile of maritime accidents that occurred in the Strait of Istanbul in the 2006-2015 period have been examined simultaneously with the variables of hourly wind speed and wind direction in the region. Results that were obtained indicate that accidents impending to happen can be prevented in the Strait of Istanbul if the patrol tugs take action when the ships were experiencing breakdown and/or navigational difficulties. The effectiveness, response time and response options of the proposed patrol tugboats were evaluated in two different scenarios where ship and currents are parallel and anti-parallel. [ABSTRACT FROM AUTHOR]

Navigation through narrow waterways always requires expertise and help from local authorities to facilitate safer and faster navigation. The recent Suez Canal blockage by the ultra-large container ship Ever Given running aground has resulted in a temporary halt and extended delay in goods transportation. Blockage of such a critical waterway has raised major concerns about the risk involved in navigation. This commentary attempts to analyze the background and chain of events leading up to the blocking of the Suez Canal. In this process, the issues related to navigation and following up salvage efforts are analyzed to identify the critical areas of improvement. Based on these identifications, suggestions for future improvement of navigation and better preparedness to optimize the salvage efforts have been identified. These suggestions include digitalization, prediction-based navigation capabilities, development of tugboats and associated tools, and so forth. [ABSTRACT FROM AUTHOR]