Navigated Research Articles

TRENDS IN THE DEVELOPMENT OF COMPUTING MEANS FOR CELESTIAL NAVIGATION

The basis for ensuring the navigational safety of a ship is knowing the coordinates of its location at a given point in time. In modern conditions, the coordinates of the ship position in most cases are obtained using the global navigation satellite systems. However, there is a problem when using these systems, namely, failures in receiving navigation information from satellites. The causes of failures are interference to the radio signal of both natural origin and artificial (destructive) origin, caused by the interference of radio suppression equipment. A solution to the problem of detection of destructive interference in the radio channel of the satellite-receiver by using navigation on celestial bodies is proposed. The possibility of using navigation on celestial bodies in modern conditions implies efforts to improve this method and includes a set of measures. Among the set of measures, two directions are distinguished. The first direction is the improvement of the means for measuring the navigation parameters. The second direction is the improvement of the computing tools necessary for calculating the coordinates of the ship position, as well as solving navigational problems of ensuring navigation safety, namely, determining instrument corrections, providing time service on the ship, determining illumination and selection of luminaries for observation. The second direction of improving the navigation of the celestial bodies, namely, the identification of the trend in the development of computing means of navigation on the celestial bodies is considered in the paper. As a result of the work, the general trend of the global market which can be used to judge the growth and popularization of the maritime industry, is presented; the uneven development of the functionality of the presented programs is revealed; the advantages and disadvantages of this phenomenon are described. As confirmation of the growing relevance, reports of the international analytical organizations indicating the growth of the marine radio electronics market by 8.1 % per year until 2025 are cited.

Use of pulsars for ship navigation: an alternative to the sextant

AbstractA new method is proposed for determining a ship's position at sea using naturally occurring pulsar signals to provide an alternative to the sextant. Use is made of four distinct pulsar radio signals whose timing stabilities are comparable to atomic clocks and whose characteristic signatures can be used as natural radio navigation beacons. Pulse peak time difference measurements, accurate to within 10−5and 10−6s, were generated for a key reference observatory which provides long-term pulsar timing observations and for the unknown ship location. These time differences when multiplied by the velocity of light provide a distance value that is fundamental in calculating the ship's position. Resultant simulations provided a position accuracy to ≈1⋅1 km (≈0⋅6 nm) for the higher timing difference measurement. A single-pulsar-based approach, which gave a position accuracy to ≈2⋅8 km (≈1⋅5 nm), was also investigated for affordable equipment solutions and comparison with NASA space-based navigation experiments.

Detection of maritime traffic anomalies using Satellite-AIS and multisensory satellite imageries: Application to the 2021 Suez Canal obstruction

AbstractThis study summarises the scenario of maritime traffic anomalies, like the increased congestion and U-turn of ships caused by the ship grounding in the Suez Canal in March 2021. Here, satellite automatic identification system based ship trajectories, and Sentinel-1 and Sentinel-2 images based ship positions are analysed after subdividing the study area into seas, lakes and canals. The results show that the blockage affected the maritime traffic for more than three weeks, waiting ship numbers increased from 5 to 122, and daily one to three ships made a U-turn between 23 and 31 March in the Gulf of Suez. Ship density also increased to more than double in Bitter Lakes with a minimum waiting time of 7 days. Hence, to avoid such prolonged waiting of ships, we propose a warning method based on the sharp speed decrease rate, U-turn and congestion.

A Method for Correcting the Closest Point of Approach Index During Vessel Encounters Based on Dimension Data From AIS

In the field of maritime safety, ship encounters are a core component of traffic management and analysis. The calculation of the closest point of approach (CPA) is one of the most important methods for collision risk assessment during an encounter. Due to the factors influencing collision risk in water transportation, the existing CPA index exhibits uncertainties in the awareness of dangerous situations. In this paper, to overcome the shortcoming of the CPA index, which does not consider the vessel dimension, we utilize a polygon to represent the ship position based on related information from automatic identification system (AIS) and propose a method to obtain corrected values of the distance at the CPA (DCPA) and time to the CPA (TCPA) through the geometric relationship of the relative motion between involved vessels. Case analysis is conducted through practical encounter cases in a traffic-intensive area outside a port. The comparison results verify that the proposed method effectively reduces the uncertainties of the original point-based CPA index to better assess the collision risk. The advantage of our correction method is that the dimension-related influencing factors can be integrated without manual intervention, and the improved index retains the objectivity and clear physical meaning of the original CPA index. Therefore, the proposed method has high practical value, especially in busy water areas where a high-risk assessment accuracy is required.

Improved ship position stability on offshore-based dynamic position maintenance with the PID method

Anchor Handling Tug and Supply (AHTS) vessel is a type of vessel designed to support oil and gas drilling facility activities and work, in addition to serving offshore oil and gas exploration work. The special feature of this ship is that the hull is not too large, equipped with a large auxiliary engine with propeller driving (double) at the rear and equipped with maneuvering aids to maintain position, namely Bow Thruster, Stern Thruster and Dynamic Position System for AHTS ships so that they can work maneuvering at sea to be fast and accurate in determining the ship's position. One solution to overcome this problem in this research is to create a control simulation so that the ship remains stable in a state of floating above the offshore waters. The control method used is a PID-based dynamic method. The sensors used are accelerometers and gyroscopes that can read the movement and angle changes in the blood vessels. From the results of testing and analysis of parameters Kp: 60, Ki: 2, and Kd: 30 for ship control gave good results, namely the ship will return to its original position when it floats.

어구부표의 표시 방법 개선에 대한 입법론적 고찰 - 어구 손상사고 사례를 중심으로 -

Accidents between small ships and small fishing vessels sailing in the coastal waters of Korea and facilities installed for fishing on the coast occur frequently every year. These accidents are mainly caused by aquaculture farms, fishing nets, and gill nets installed in coastal waters. Common causes of ship accidents include the negligence of the officers of the crew on a sailing vessel, non-compliance with course maintenance, confirmation of ship position, and general navigation. It can be in various ways, such as non-compliance with the principles and regulations on the prevention of collisions at sea. In particular, to examine the cause of the accident related to the fishing net damage accident, it was analyzed through the decision of the Maritime Safety Tribunal, and as a result, the cause of the accident was neglect of the boundary, not securing an appropriate distance from the installed fishing gear, and insufficient establishment of the voyage plan. In order to reduce accidents caused by these human factors, it takes a long time and a lot of money, such as constant safety education for seafarers or changes to systems such as ship safety management system. In this paper, measures to reduce the occurrence of accidents by removing other risk factors other than human factors by intuitively discovering fishing gear a little faster are presented in 「Fisheries Act」, 「Rules on the Management of Fishing Licenses, etc.」, 「Aquaculture and fishing grounds」 We will try to find a way to reduce the damage to fishing nets by identifying and improving problems in the “Installation Standards for Marking Facilities” and “Aquaculture Industry Development Act”.

Finite-Time Controller Design for the Dynamic Positioning of Ships Considering Disturbances and Actuator Constraints

Focusing on dynamic positioning (DP) systems for ships, which are subject to environmental disturbances and actuator constraints, this paper presents a finite-time controller that uses a disturbance observer with the aid of a backstepping technique. First, to estimate the time-varying and unknown environmental disturbances in finite time, two sliding-mode disturbance observers are constructed. Specifically, an adaptive disturbance observer (ADO) effectively decreases undesired chattering without the need for prior information on environmental disturbances. Then, to handle the actuator constraints, the designed control forces are distributed into multiple actuators using a control allocation algorithm to obtain the actual forces. Next, an auxiliary dynamic system is built to compensate for velocity tracking errors induced by the mismatch of the DP control law and thruster forces. Then, with the designed ADO and the auxiliary dynamic system, a finite-time controller with a fast exponential-reaching law is designed; this ensures that the positioning errors and the sliding surface converge to zero at a fast convergence rate. Finally, numerical simulations are presented: these present a cable-laying ship experiencing wind, currents, and waves in different sea states. The results show the effectiveness of the presented control scheme.

Data fusion and machine learning for ship fuel efficiency modeling: Part II – Voyage report data, AIS data and meteorological data

When voyage report data is utilized as the main data source for ship fuel efficiency analysis, its information on weather and sea conditions is often regarded as unreliable. To solve this issue, this study approaches AIS data to obtain the ship's actual detailed geographical positions along its sailing trajectory and then further retrieve the weather and sea condition information from publicly accessible meteorological data sources. These more reliable data about weather and sea conditions the ship sails through is fused into voyage report data in order to improve the accuracy of ship fuel consumption rate models. Eight 8100-TEU to 14,000-TEU containerships from a global shipping company were used in experiments. For each ship, nine datasets were constructed based on data fusion and eleven widely-adopted machine learning models were tested. Experimental results revealed the benefits of fusing voyage report data, AIS data, and meteorological data in improving the fit performances of machine learning models of forecasting ship fuel consumption rate. Over the best datasets, the performances of several decision tree-based models are promising, including Extremely randomized trees (ET), AdaBoost (AB), Gradient Tree Boosting (GB) and XGBoost (XG). With the best datasets, their R2 values over the training sets are all above 0.96 and mostly reach the level of 0.99–1.00, while their R2 values over the test sets are in the range from 0.75 to 0.90. Fit errors of ET, AB, GB, and XG on daily bunker fuel consumption, measured by RMSE and MAE, are usually between 0.8 and 4.5 ton/day. These results are slightly better than our previous study, which confirms the benefits of adopting the actual geographical positions of the ship recorded by AIS data, compared with the estimated geographical positions derived from the great circle route, in retrieving weather and sea conditions the ship sails through.

Design and implementation of AI chatbot for COLREGs training

The education and training for the maritime industry require renewed focus in the face of technological changes and increasing digitalization. Artificial intelligence presents an avenue for further research that can positively impact efficiency and competence development. Among many applications of artificial intelligence in education, conversational agents or chatbots have gained increased interest in recent years. This paper describes the design and implementation process of “FLOKI”—a chatbot aimed at assisting maritime trainees in learning Collision Avoidance Regulations (COLREGs). For the design of the chatbot, IBM Watson Assistant®—a cognitive computing service—was utilized, which enables the use of Application Programming Interfaces (APIs) in its cloud server. A selected number (n = 18) of 2nd year B.Sc. in Nautical Science students in a Norwegian maritime university interacted with the chatbot for reflecting on their knowledge about COLREGs. In addition to demographic data, the maritime trainees were asked to answer questions related to user experience utilizing the System Usability Scale (SUS). The findings are discussed along with their implications and future research directions involving AI in maritime education and training.

Research on RCS measurement of ship targets based on conventional radars

Abstract A measurement method and system based on conventional radars has been proposed to address the problem of radar cross-section (RCS) measurement of ship targets in open seas. Calibration errors for RCS measurement on ground plane range (GPR) are analysed, and the error elimination method and accurate RCS calculation formula are given. An RCS measurement system is designed by improving conventional radars. These systems measure two Luneburg lens reflectors of different sizes on the lake. The average RCS of the big Luneburg lens reflector is obtained, and the error is calculated to be 2.73% compared with its actual value, which verifies the rationality of the proposed measurement method and system. The system measures the RCS of a ship in the open sea and obtains its circumferential RCS distribution. The effect of the error in the ship's position calculation on the RCS measurement results is analysed, and the uncertainty range of the error is obtained.

Situational Approach of Teaching Speaking Maritime English in Merchant Marine Polytechnic of North Sulawesi

English communication skills in the areas of speaking, listening, reading, and writing. However, in many students' minds communication means only interaction between the speaker and the listener. Teaching English at maritime universities and nautical colleges involves not only teaching the language and the sea-related terminology but also making the students aware of the cross-cultural issues and problems that they may encounter in their work onboard ships. The best way of teaching is, how the teacher, instructor, and lecturer can choose and use the right teaching method. FAIES is one of the unique and well-known methods in teaching which can adapt to many situations in the classroom and makes the students feel easy to understand and study comfortably during the lesson especially in speaking English. According to Freud in Wollheim (1981), FAIES (First Aid in English System) is the teaching method to emphasize or stress communication, which consists of a directional approach, functional approach, situational approach, and drilling technique. Maritime English is largely restricted to IMO Standard Marine Communication Phrases, which build basic knowledge of English and had been drafted in a simplified version of maritime English. In terms of maritime education, the current simulator-based studies can be divided into two areas: marine engineering and nautical science. In particular, human factor specialists work in these two fields addressing issues concerning the relationship between humans and technology, such as simulators (Lützhöft et al. 2017). A multitude of new methodologies has been explored and discussed in recent years in an attempt to approach the training and testing of the proficiency of maritime English that meets the international standards laid out in STCW.

딥러닝 기반 객체 탐지 결과의 불확실성을 고려한 자동 선박 탐지 및 추적

Recently, autonomous surface vehicles (ASVs) have attracted much research attention because of their potential effectiveness in carrying out various maritime missions such as surveillance and environmental monitoring. Situation awareness is a critical ability, and the camera is an essential sensor for ASVs in conducting such missions by automatically detecting and tracking objects in the surrounding environment. We detect and track the objects robustly by extracting the detection uncertainty and applying it to the tracking process. This study addresses automatic ship detection and tracking, considering the uncertainty of deep learning-based object detection using an onboard monocular camera. Gaussian YOLOv3, a deep learning-based object detection algorithm, is applied to detect a ship and estimate the uncertainty of the detection result. The detection results are sampled with uncertainty and propagated based on the camera geometry. Finally, the position of the target ship is estimated by a particle filter using the sampled detection results as measurements.

Ship Dynamic Positioning Control Based on Active Disturbance Rejection Control

Nowadays, Dynamic Positioning (DP) is applied to various tasks such as subsea pipeline laying and the requirements for the positioning performance in marine operations are higher and higher. The main objective of this paper is to design a DP controller based on the Active Disturbance Rejection Control (ADRC) to solve the problems of long response time, large overshoot and low positioning accuracy in ship positioning. Firstly, the mathematical models of the ship and environmental disturbances are established. Secondly, the basic principle of ADRC is described. Meanwhile, stability analysis of the control system is introduced. Thirdly, ADRC is improved by the fal function filter and phase prediction method which solve the problem of dither and phase delay in tracking differentiators. Finally, simulations are carried out to verify the performance of the designed ADRC and the improved ADRC. Several simulation results show that the designed ADRC can realize the fixed-point control of the ship, which effectively solves the problems of long response time, overshoot and positioning accuracy, and compared with the traditional ADRC, the improved ADRC can reduce the error of straight track control, which indicates that ADRC can meet the requirements for the positioning performance and has a strong application value.

Analysis of Changing Levels of Ice Strengthening (Ice Class) among Vessels Operating in the Canadian Arctic over the Past 30 Years

Climate change is impacting sea ice extent and thickness in the Canadian Arctic, creating an increase in maritime accessibility that may accentuate risks related to ship operations due to a related increase in sea ice mobility. The overall risk to ships operating in regions with mobile sea ice will vary significantly depending on the ice class (i.e., level of ice strengthening) of the vessel. Several studies have examined the implications of sea ice change for ship operations, but to date limited analysis has been conducted to understand whether levels of ice strengthening are changing among vessels operating in the Arctic. To address this research gap, more than 100,000 ship position reports covering a 30-year time-period were obtained from the Canadian Coast Guard in order to evaluate changes in shipping activities across Arctic Canada by vessel ice class. Between 1990 and 2019, there has been a substantial reduction in the number of highly strengthened PC3 ships (25%) and a large increase in the number of medium-strengthened PC7 (605%) and low-strengthened 1B (180%) vessels. These trends are particularly acute for certain vessel types, including bulk carriers, cargo ships, and passenger vessels, and also within certain geographic areas, including the Northwest Passage. The combination of climate change – induced increases in sea ice – related navigational hazards and the observed decrease in highly strengthened ships operating in the Canadian Arctic could lead to a larger number of accidents and incidents as a proportion of total operational vessels, and points to the need for infrastructure and service investment congruent with overall increases in particular types of maritime shipping activities expected in the near- to medium-term future.

Situational Awareness for Autonomous Ships in the Arctic: mMTC Direct-to-Satellite Connectivity

The maritime autonomous surface ship (MASS) promises a revolution in naval logistics by offering sustainability, safety, and operational costs reduction. The MASS can bring to the Arctic and other hard-to-reach regions numerous social and economic benefits, thus contributing to equalizing access for human and machine terminals to connectivity, and equate the life quality of their inhabitants with that of other regions. In this article, we suggest a hybrid communication architecture that separates a ship's data traffic into awareness and emergency components. For the former traffic, we advocate the possibility of direct-to-satellite using massive machine-type communication (mMTC) and low-power wide-area network (LPWAN) technologies. To validate this hypothesis and investigate the potential performance and effect of different design and configuration parameters, we conduct simulations based on real-life positions of ships and satellites, traffic patterns, and the LoRaWAN connectivity model. Our results demonstrate the suggested approach's feasibility and clarify the different parameters' effects on the connectivity performance for the classical LoRa and novel long-range frequency hopping spread spectrum modulation coding schemes. Notably, the combination of multi-connectivity of LoRaWAN LPWAN technology and multi-satellite visibility dramatically boosts the probability of packet delivery.

Weather Routing System Architecture Using Onboard Data Collection and Route Optimisation

Abstract This paper describes the architecture of a weather routing system consisting of two key elements: onboard monitoring and route optimiser sub-systems. The former is responsible for collecting various onboard measurements, such as current ship position or ship motion variables. These data, when gathered and processed, are then used for fine-tuning a ship model. The model, together with weather forecasts, is utilised by a multi-objective route optimiser to estimate forecasted ship responses during the voyage. The route optimiser has been developed in a client-server architecture to reallocate all necessary high-tech resources to the server side and keep the client software as simple and light as possible. The system also includes a module responsible for optimising transmission costs, to reduce onboard transmission during the voyage. The entire solution has been deployed onboard the demonstrator ship ‘Monte da Guia’ and tested during its operations at sea.

Implementation of Repetition and Chain Drill at Akademi Maritim Nusantara Cilacap

The act of communicating using English is still an obstacle for students, especially for countries that make English as a foreign language. English conversation must be mastered fluently by students of Akademi Maritim Nusantara Cilacap, especially the Nautical Sciences Study Program. This becomes an obligation because as seafarers, graduates will definitely have to deal with many people from other countries. Learning English conversation by imitation is seen as still relevant when viewed from the position of English as a foreign language in Indonesia. This study aims to see the impact of applying repetition and chain drill methods in learning Maritime English at the Akademi Maritim Nusantara Cilacap. The Repetition and Chain Drill methods are part of a language teaching method called the Audio-Lingual Method. Both methods are implemented in one Nautical Science class which contains 33 students. With the help of 33 Nautical program students, the research was done utilizing the Classroom Action Research approach. Three study steps yielded the necessary data. Researchers assess each student’s fluency and pronunciation in various ways. The results showed that there was an increase in the average value between stages. It also proves that learning with repetition and chain drill methods helps students start English conversation.

Tugas dan Kewenangan Vts Batam dalam Pengawasan Lalu Lintas Pelayaran Di Selat Singapura

The government, as well as all of us as rulers, managers and users of the sea, are responsible for regulating the flow of traffic to ensure that maritime activities run smoothly and safely. This requires defining channel and crossing functions, which can be done through the use of navigational hazard labeling and updating of water level conditions. The purpose of this study is to find out how the VTS legal duties and authorities are arranged in the supervision of shipping traffic in the Singapore strait, how the VTS Batam duties and authorities are carried out, and what factors hinder the VTS legal duties and authority in supervising shipping traffic in the strait. Singapore. This study collects primary data through fieldwork using a normative and sociological research approach. To collect primary data, descriptive technique is combined with a normative approach (legal research). For marine activities, some locations must be equipped with a Vessel Traffic Information System (VTS) or Radar Beacons for security and strategic considerations. The decision will be announced by the Minister as soon as all the shipping lane requirements have been met, and will be communicated to the maritime world through the International Maritime Organization (IMO), in accordance with the convention that has adopted the standard for the use of shipping lanes. reporting system of ships at sea to operators on land traffic monitoring. This equipment has a VTIS attached to it, enabling it to detect the ship's name, position, speed and course. This data is then entered into the system and continuously monitored.

A New Method of Inland Water Ship Trajectory Prediction Based on Long Short-Term Memory Network Optimized by Genetic Algorithm

Ship position prediction plays a key role in the early warning and safety of inland waters and maritime navigation. Ship pilots must have in-depth knowledge of the future position of their ship and target ship in a specific time period when maneuvering the ship to effectively avoid collisions. However, prediction accuracy and computing efficiency are crucial issues that need to be worked out at present. To solve these problems, in this paper, the deep long short-term memory network framework (LSTM) and genetic algorithm (GA) are introduced to predict the ship trajectory of inland water. Firstly, the collected actual automatic identification system (AIS) data are preprocessed and a series of typical trajectories are extracted from them; then, the LSTM network is used to predict the typical trajectories in real time. Considering that the hyperparameters of the LSTM network have difficulty obtaining the optimal solution manually, the GA is used to optimize hyperparameters of LSTM; finally, the GA-LSTM trajectory prediction model is constructed with the optimal network parameters and compared with the traditional support vector machine (SVM) model and LSTM model. The experimental results show that the GA-LSTM model effectively improves the accuracy and speed of trajectory prediction, with outstanding performance and good generalization, which possess certain reference values for the development of collision avoidance of unmanned ships.

An Analysis of the Status of Women Leadership in Education Sector of the Catchment Areas of Wolaita Sodo University

The purpose of this study was to investigate causes for the underrepresentation of women in top positions of the education sector of the catchment areas of Wolaita Sodo University. Hence, to realize this purpose, secondary school teachers, principals of secondary schools, and supervisors of all levels, and heads of education offices and departments of Dawro and Wolaita administrative zones were used as the target population. In order to make the study manageable, the sample secondary schools teachers were selected by simple random sampling technique, and principals and supervisors were selected through purposive sampling techniques. Descriptive survey research design and concurrent mixed approaches were applied. Both close-ended and open-ended questionnaires and unstructured interviews were used to collect data. Frequency counts, and percentages were employed for quantitative data through close-ended questionnaire. Data through qualitative questionnaire were narrated and used for the sake of triangulation. The finding showed that women were underrepresented due to self-related factors, socio-cultural factors, institutional factors, economic factors, and political-legal factors in the leadership positions of secondary and primary schools, principal ship positions, and supervisory positions. Thus, it was concluded that though the Federal Democratic Republic of Ethiopia has taken a number of affirmative actions and stipulated the issue of empowering women in the constitution, yet women were strikingly underrepresented in Dawro and Wolaita zones of south Ethiopia, particularly in the education sector. Therefore, it was recommended that taking into account that women are half the population, talented in leadership and management and the advantage of gender diversity in educational leadership institutions, government and the large society should strive towards empowering women. Keywords: underrepresentation, women, women leadership, leadership DOI: 10.7176/JEP/13-10-04 Publication date: April 30 th 2022