The Automatic identification System (AIS) has been mainly designed to improve safety and efficiency of navigation, environmental protection, coastal traffic monitoring simplifying identification and communication. Additionally,...

Global and regional positional accuracy assessment is of the highest importance for any satellite navigation system, including the Global Positioning System (GPS). Although positioning error can be expressed as a vector quantity with direction and magnitude, most of the research focuses on error magnitude only. The positional accuracy can be evaluated in terms of navigational quadrants as further refinement of error distribution, as it was shown here. This research was conducted in the wider area of the Northern Adriatic Region, employing the International Global Navigation Satellite Systems (GNSS) Service (IGS) data and products. Similarities of positional accuracy and deviations distributions for Single Point Positioning (SPP) were addressed in terms of magnitudes. Data were analyzed during the 11-day period. Linear and circular statistical methods were used to quantify regional positional accuracy and error behavior. This was conducted in terms of both scalar and vector values, with assessment of the underlying probability distributions. Navigational quadrantal positioning error subset analysis was carried out. Similarity in the positional accuracy and positioning deviations behavior, with uneven positional distribution between quadrants, indicated the directionality of the total positioning error. The underlying distributions for latitude and longitude deviations followed approximately normal distributions, while the radius was approximated by the Rayleigh distribution. The Weibull and gamma distributions were considered, as well. Possible causes of the analyzed positioning deviations were not investigated, but the ultimate positioning products were obtained as in standard, single-frequency positioning scenarios.

The characterization of ship routes and route similarity measurement based on Automatic Identification System (AIS) data are topics of various scientific interests. Common route research approaches use available AIS identifiers of ship types. However, assessing route and similarity profiles for individual fleets requires collecting data from secondary sources, dedicated software libraries or the creation of specific methods. Using an open-source approach, public AIS and ship data, we evaluate route characteristics for the container ships of a single fleet in a six-month period, calling on two selected ports of the shipping line on the USA East Coast. We evaluate the routes in terms of length, duration and speed, whereas for the similarity measurement we employ the discrete Fréchet distance (DFD). The voyage length, duration and average speed distributions were observed to be moderately positive (0.77), negative (−0.62), and highly positively skewed based on the adjusted Fisher–Pearson coefficient of skewness (1.23). The most similar voyages were from the same ships, with the lowest discrete Fréchet distance similarity value (0.9 NM), whereas 2 different ships had the most dissimilar voyages, with the highest DFD value (14.1 NM). The proposed methodology enables assessment of similarities between individual ships, or between fleets.

A change in the main operating parameters of a high speed turbocharged direct injection diesel engine MAN D0826 LOH15 during the fuel mass flow variation has been analyzed. On the basis of two measurement sets, on two different engine...

Sanjin Valčić, Srđan Žuškin, David Brčić, Davor Šakan; Review, pp. 135-140 Download

The mandatory ECDIS transitional period has ended just recently. The technology matured and the progress towards the ECDIS as a primary means of navigation has continued. Safe and effective navigation mostly relies on accurate and valid positioning despite the system’s technological advancement. In general, the frequency of plotting and monitoring of ship’s position depends on two factors: employed navigational means and navigational areas. When using paper charts for primary means of navigation, position plotting frequency usually ranges from several minutes to one hour according to the Safety Management System (SMS) or other relevant requirements. In the case of ECDIS navigation, primary position is continuously displayed, mostly by the employment of satellite positioning means, with the possibility of secondary positioning display, depending on the source. Validation by position cross-checking is therefore essential for preventing overreliance on ECDIS primary position. In different navigational stages the navigator can use well known methods from celestial, coastal or electronic navigation. In the proposed paper, accuracy and complexity of positioning methods commonly used by the navigators are evaluated. The obtained results are correlated to primary positioning validation in ECDIS and compared with maritime user requirements, recommendations and respective resolutions. The research is accompanied with survey results on position checking methods conducted among the navigators. Results revealed that most of the navigators validate primary position, however there are misinterpretations between position validation, position fixing and secondary position source. Among stated, other overall and specific findings are presented and discussed. Future research directions are proposed in terms of the necessity of position checking, availability of positioning sources and further development of the system.