Towards Paperless Vessels: A Master’s Perspective

The transitional period of implementation of the Electronic Chart Display and Information System (ECDIS) expired on July 1st, 2018. As for this date onward, vessels of 3000 GT or more subject to the Safety of Life at Sea (SOLAS) Convention and engaged in international voyages, must be fitted with an official ECDIS system. The Convention furthermore requires mandatory possession of navigational equipment as an adequate back-up. In case that independent system is used for this purpose, there is no further obligation for a vessel to possess traditional paper navigational charts and it can be considered as paperless. Beside paper charts, this term also implies digital nautical publications and probably an electronic ship’s log in the foreseeable future. The interpretation of ECDIS differs considering particular rank of an Officer of the Watch (OOW) and its engagement towards the system. The system should be accepted by OOWs as true end-users. The proposed paper elaborates opinions and standpoints of decisive end-users towards the system, its role as a primary navigational means, and the fact that traditional navigation conduct is replaced by digital means. For this purpose a survey between OOWs was conducted focusing on their answers to respective questions. The sample size allowed for the observation of opinions over several years and the definition of the ECDIS acceptance level. Results are presented and discussed together with proposals of new activities which have to be carried out to improve the safety of navigation by the ECDIS system and its further development

Single-frequency GPS positioning performance Around the time of the Chilean 2010 earthquake

Premda u ograničenim geoprostornim razmjerima, potresi su poznati izvori geomagnetskih i ionosferskih poremećaja. Kako navedeni poremećaji također utječu na značajke širenja radiovalova, može se očekivati utjecaj potresa na učinkovitost i kvalitetu rada satelitskih navigacijskih sustava. U radu su objavljeni rezultati analize kvalitete rada jednofrekvencijskih GPS prijemnika smještenih na odabranim položajima širom svijeta u vrijeme potresa koji je pogodio Čile 2010. godine. Analizirana je kvaliteta jednofrekvencijskog GPS pozicioniranja na odabranim referentnim stanicama u vremenskom intervalu neposredno nakon nastupa potresa. Također, ustanovljeno je vrijeme povrata funkcionalnosti GPS sustava u prvobitno operativno stanje. U istraživanju je vidljiv značajan kratkoročni poremećaj kvalitete rada GPS sustava na svim promatranim stanicama. U procesu sakupljanja podataka GPS opažanja umanjen je utjecaj raznih izvora pogrešaka u postupku određivanja položaja sustavom GPS, isključujući GPS ionosfersko kašnjenje i pomak u referentnom koordinatnom okviru. Teorijske analize pokazale su kako je utjecaj pomaka u referentnom koordinatnom sustavu zanemariv na učinkovitost GPS pozicioniranja; na ovaj način, ionosferski utjecaji izazvani potresom nastupaju kao najvjerojatniji uzrok degradacije kvalitete pozicioniranja jednofrekvencijskih GPS prijemnika širom svijeta.The earthquakes are known sources of geomagnetic and ionospheric disturbances, although on the restricted geospatial scale. Since such disturbances also affect the radio wave propagation characteristics, it is expected for the earthquakes to cause an impact on the satellite navigation systems’ performance. In this paper we have reported the results of the single-frequency GPS performance analysis at various locations around the globe at the time of the Chilean 2010 earthquake occurrence. The single-frequency GPS positioning performance at the selected reference sites in the time interval immediately following the Chilean 2010 earthquake outbreak has been analysed, and the GPS recovery time identified. Our study shows considerable short-term GPS performance disturbance observed at every location taken into consideration. The GPS observables collection process mitigates the impact of various GPS positioning error sources, excluding the GPS ionospheric delay and the reference frame shift. A theoretical analysis has shown negligible effects of the reference frame shift on the GPS positioning performance, leaving the ionospheric effects as the most probable cause of the earthquake-induced short-term single-frequency GPS performance degradation around the world

A MODEL OF NON-SPECIFIC DAILY PATTERN OF THE SATELLITE POSITIONING SIGNAL IONOSPHERIC DELAY

U ukupnom proračunu pogreške određivanja položaja jednofrekvencijskim GNSS prijamnicima, ionosfersko kašnjenje satelitskog signala predstavlja najznačajniju utjecajnu veličinu. GPS modelom ispravke ionosferskog kašnjenja (prema Klobucharu), dnevna dinamika ionosferskog kašnjenja opisuje se na globalnoj razini. U doktorskom radu predložen je regionalni model utemeljen na uočenim nespecifičnim pravilnostima u dnevnom hodu ionosferskog kašnjenja signala za određivanje položaja. Nespecifične pravilnosti pojavljuju se pod određenim uvjetima; tijekom mirnog svemirskog vremena, nepobuđene ionosfere, u razdobljima ljetnih mjeseci te na području srednjih geografskih širina. Identificirana lokalna dinamika ionosferskog kašnjenja razlog je i motivacija za provedeno istraživanje, s ciljem unaprjeđenja pružanih usluga i općenito rada GNSS sustava. Model je izrađen na temelju izmjerenih vrijednosti ionosferskog kašnjenja, koje su izvedene iz opažanja kodnih i faznih pseudoudaljenosti. Pri tome su korišteni podaci s referentnih IGS stanica unutar Jadranske regije. Model je verificiran u razdobljima unutar kojih prevladavaju definirani uvjeti okoliša širenja signala za satelitsko određivanje položaja. Dobivene vrijednosti uspoređene su sa stvarnim vrijednostima ionosferskog kašnjenja, te s vrijednostima ionosferskog kašnjenja modeliranim prema Klobucharovom modelu ispravke. Model je ispitan na trima različitim lokacijama u području Jadranske regije u 2006. i 2007. godini. Rezultati su pokazali kako, u odnosu na Klobucharov model, predloženi model u zadanim uvjetima pruža točnije ispravke ionosferskog kašnjenja. Time je potvrđena primjenjivost predloženog modela za područje Jadranske regije i okolice. Značajke modela razmotrene su sa stajališta uspješnosti, prednosti i ograničenja modela. Prikazane su znanstvena i praktična mogućnost primjene modela i ostalih rezultata istraživanja. Analiza pogrešaka modela i njihovih uzroka postavlja smjernice za daljnja istraživanja lokalnih i globalnih uvjeta ionosferske dinamike te Sunčeve i geomagnetske aktivnosti.Satellite positioning signal ionospheric delay has been identified as a single major contributor in total satellite positioning error budget. Daily dynamics of ionospheric delay are described globally by utilising the GPS standard (Klobuchar) ionospheric model. In this doctoral thesis, a regional ionospheric delay correction model has been proposed. The model is based on observed daily pattern ionospheric delay non-specific regularities, which are occuring under specified conditions; during quiet space weather, undisturbed ionosphere, in summer months period and at middle geographic latitudes. The local ionospheric delay dynamics are the reason and a motivation for conducted research, which was carried out aiming at GNSS services improvement and system performance. The model is developed on the basis of measured values of ionospheric delay. These values were derived from code and phase pseudorange observables from Adriatic region reference IGS stations. The model has been verified in time periods where defined conditions of satellite positioning signal propagation environment were prevailing. Obtained values were compared with actual ionospheric delay values, as well as with ionospheric delay values obtained with the Klobuchar ionospheric correction model. The proposed model has been tested in three different locations in the Adriatic region, in years 2006 and 2007. The results showed that, under specified conditions and controlling parameters, proposed ionospheric model provides more accurate ionospheric delay corrections compared to the Klobuchar model. The proposed model's applicability in the Adriatic region and surrounding has been confirmed. Model properties have been discussed from the accomplishment, advantages and limitations aspect. The potential of the model's scientific and practical appliance is presented, along with thesis research results. A model error analysis and error causes will set guidelines for further research activities regarding local and global ionospheric dynamics conditions, as well as solar and geomagnetic activity exploration

A MODEL OF NON-SPECIFIC DAILY PATTERN OF THE SATELLITE POSITIONING SIGNAL IONOSPHERIC DELAY

U ukupnom proračunu pogreške određivanja položaja jednofrekvencijskim GNSS prijamnicima, ionosfersko kašnjenje satelitskog signala predstavlja najznačajniju utjecajnu veličinu. GPS modelom ispravke ionosferskog kašnjenja (prema Klobucharu), dnevna dinamika ionosferskog kašnjenja opisuje se na globalnoj razini. U doktorskom radu predložen je regionalni model utemeljen na uočenim nespecifičnim pravilnostima u dnevnom hodu ionosferskog kašnjenja signala za određivanje položaja. Nespecifične pravilnosti pojavljuju se pod određenim uvjetima; tijekom mirnog svemirskog vremena, nepobuđene ionosfere, u razdobljima ljetnih mjeseci te na području srednjih geografskih širina. Identificirana lokalna dinamika ionosferskog kašnjenja razlog je i motivacija za provedeno istraživanje, s ciljem unaprjeđenja pružanih usluga i općenito rada GNSS sustava. Model je izrađen na temelju izmjerenih vrijednosti ionosferskog kašnjenja, koje su izvedene iz opažanja kodnih i faznih pseudoudaljenosti. Pri tome su korišteni podaci s referentnih IGS stanica unutar Jadranske regije. Model je verificiran u razdobljima unutar kojih prevladavaju definirani uvjeti okoliša širenja signala za satelitsko određivanje položaja. Dobivene vrijednosti uspoređene su sa stvarnim vrijednostima ionosferskog kašnjenja, te s vrijednostima ionosferskog kašnjenja modeliranim prema Klobucharovom modelu ispravke. Model je ispitan na trima različitim lokacijama u području Jadranske regije u 2006. i 2007. godini. Rezultati su pokazali kako, u odnosu na Klobucharov model, predloženi model u zadanim uvjetima pruža točnije ispravke ionosferskog kašnjenja. Time je potvrđena primjenjivost predloženog modela za područje Jadranske regije i okolice. Značajke modela razmotrene su sa stajališta uspješnosti, prednosti i ograničenja modela. Prikazane su znanstvena i praktična mogućnost primjene modela i ostalih rezultata istraživanja. Analiza pogrešaka modela i njihovih uzroka postavlja smjernice za daljnja istraživanja lokalnih i globalnih uvjeta ionosferske dinamike te Sunčeve i geomagnetske aktivnosti.Satellite positioning signal ionospheric delay has been identified as a single major contributor in total satellite positioning error budget. Daily dynamics of ionospheric delay are described globally by utilising the GPS standard (Klobuchar) ionospheric model. In this doctoral thesis, a regional ionospheric delay correction model has been proposed. The model is based on observed daily pattern ionospheric delay non-specific regularities, which are occuring under specified conditions; during quiet space weather, undisturbed ionosphere, in summer months period and at middle geographic latitudes. The local ionospheric delay dynamics are the reason and a motivation for conducted research, which was carried out aiming at GNSS services improvement and system performance. The model is developed on the basis of measured values of ionospheric delay. These values were derived from code and phase pseudorange observables from Adriatic region reference IGS stations. The model has been verified in time periods where defined conditions of satellite positioning signal propagation environment were prevailing. Obtained values were compared with actual ionospheric delay values, as well as with ionospheric delay values obtained with the Klobuchar ionospheric correction model. The proposed model has been tested in three different locations in the Adriatic region, in years 2006 and 2007. The results showed that, under specified conditions and controlling parameters, proposed ionospheric model provides more accurate ionospheric delay corrections compared to the Klobuchar model. The proposed model's applicability in the Adriatic region and surrounding has been confirmed. Model properties have been discussed from the accomplishment, advantages and limitations aspect. The potential of the model's scientific and practical appliance is presented, along with thesis research results. A model error analysis and error causes will set guidelines for further research activities regarding local and global ionospheric dynamics conditions, as well as solar and geomagnetic activity exploration

On the possibility of COLREGS/STM integration

In the shipping industry, Sea Traffic Management (STM) system aims to represent a new paradigm in maritime safety. The idea of the STM implementation is to share information between all stakeholders, making shipping more efficient, safe, and environmentally friendly. With the growing market and related increase in marine transport and traffic, the risk of marine accidents is increasing as well. The STM provides numerous features for personnel on-board and shore to support decisions for safe navigation and operation based on real-time data. One of the services is the ship-to-ship route exchange, providing prediction of potentially dangerous situations and planning the vessel’s movement in advance. Analyses of marine accidents show that ship collisions are one of the most frequent types of marine accidents, the reason of which among all others, questions human error related to the knowledge of collision avoidance. This paper elaborates on the possibility of COLREGs/STM integration based on the use of STM ship-to-ship route exchange system. The decision model for COLREGs/STM integration procedure is presented in a way which enables suggestion on appropriate COLREG rule application in advance. Further system development is proposed as well, such as machine learning algorithms in COLREGs/STM integration, with the function of reducing the risks of marine accidents and increasing safety at sea.Peer Reviewe

Redirection aspects of Far East – Central Europe traffic flows: Facts, findings and future tendencies

The multimodal door-to-door transport chain connecting Central Europe with Far East origins predominantly calls the North European ports. However, already the geographic features are dictating the reasonable possibility of routes’ redirection via several alternatives through the Mediterranean Sea. This study represents the continuation of the research in terms of analysis and evaluation of the Southern European freight transport flow through the Northern Adriatic. The aim was to elaborate further on the justification of the possible redirection of cargoes via the Adriatic corridor. In these terms, the land segment of the transport chain from ports to the final destination was isolated and analysed. The authors were primarily guided by natural features, that are respective geographical locations and their mutual distances. For this purpose, container transport on two traffic flows was simulated, with emphasis on the land segment between the second (destination) port and the final destination. Considering the usual freight lines, the door-to-door container transport between origin and destination was selected. Both road and rail transportation modes were investigated. Besides general parameters, such as distances, time, and fuel consumption, the environmental impact for all scenarios was determined for both downstream and final fuel cycle processes. In these terms, basic environmental parameters for four possible scenarios were calculated: energy consumption, emissions of carbon dioxide, greenhouse gases, nitrogen oxides, sulphur dioxide, non-methane hydrocarbons, and particulate matter. Results are indicating that, together with a significant reduction of sea transportation impacts on the environment, the eventual redirection contributes to emissions’ mitigation and the sustainability of transportation. These results are accompanied by several initiatives in the area.  Apart from potential benefits, the findings were discussed from the reliability point of view, i.e. the ability of Northern Adriatic ports and the land infrastructure to successfully take over this task, at least to a certain extent, and finally, in a reasonable future.Peer Reviewe

Near Real-time S-AIS: Recent Developments and Implementation Possibilities for Global Maritime Stakeholders

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, historical AIS data have been used in many other areas of maritime safety, economic and environmental research. The probability of the detection of terrestrial AIS signals from space was presented in 2003, following the advancements in micro satellite technology. Through constant development, research and cooperation between governmental and private sectors, Satellite AIS (S-AIS) has been continuously evolving. Advancements in signal and data processing techniques have resulted in an improved detection over vast areas outside of terrestrial range. Some of the challenges of S-AIS technology include satellite revisit times, message collision and ship detection probability. Data processing latency and lacking the continuous real-time coverage made it less reliable for end user in certain aspects of monitoring and data analysis. Recent developments and improvements by leading S-AIS service providers have reduced latency issues. Complementing with terrestrial AIS and other technologies, near real-time S-AIS can further enhance all areas of the global maritime monitoring domain with emerging possibilities for maritime industry

Static maritime enviroment representation of electronic navigational charts in global path planning

In past years, numerous global path planning methods have been researched and applied in maritime surface navigation. Regardless of intended usage for either decision-support in manned, or autonomous vessel navigation, path planning should generate a safe and efficient route. However, prior to route generation, static maritime environment representation must be created first. Whether it is transformed in to discrete or continuous form, common approach is to use Electronic Navigational Charts (ENCs) as a basis for maritime environment representation. Nevertheless its origins, ENCs still adhere to inherited data generalisations and simplifications to be comprehensible for human navigators. This leads to limitations when considering path planning and spatial resolution at different chart scales. Furthermore, when generating the representation and path, uncertainty must be considered since the quality and accuracy of chart data varies. Although these topics have been addressed separately in their respective domains, their relations have not been researched in detail. The aim of the proposed paper is the review of electronic navigational charts, environment representation and common global path planning approaches’ relations. Forthcoming standards and technologies, such as usage of high-density charts, are presented and discussed as well.Peer Reviewe

On Global Ionospheric Maps based winter-time GPS ionospheric delay with reference to the Klobuchar model: Case study of the Northern Adriatic

Modelling of the ionospheric Total Electron Content (TEC) represents a challenging and demanding task in Global Navigation Satellite Systems (GNSS) positioning performance. In terms of satellite Positioning, Navigation and Timing (PNT), TEC represents a significant cause of the satellite signal ionospheric delay. There are several approaches to TEC estimation. The Standard (Klobuchar) ionospheric delay correction model is the most common model for Global Positioning System (GPS) single-frequency (L1) receivers. The development of International GNSS Service (IGS) Global Ionospheric Maps (GIM) has enabled the insight into global TEC dynamics. GIM analyses in the Northern Adriatic area have shown that, under specific conditions, local ionospheric delay patterns differ from the one defined in the Klobuchar model. This has been the motivation for the presented research, with the aim to develop a rudimentary model of the TEC estimation, with emphasis on areas where ground truth data are not available. The local pattern of the ionospheric delay has been modelled with wave functions based on the similarity of waveforms, considering diurnal differences in TEC behavior from defined TEC patterns. The model represents a spatiotemporal winter-time ionospheric delay correction with the Klobuchar model as a basis. The evaluation results have shown accurate approximation of the local pattern of the ionospheric delay. The model was verified in the same seasonal period in 2007, revealing it successfulness under pre-defined conditions. The presented approach represents a basis for the further work on the local ionospheric delay modelling, considering local ionospheric and space weather conditions, thus improving the satellite positioning performance for single-frequency GNSS receivers

On GPS L1 Positioning Errors’ Estimation in the Adriatic Region

Prediction of satellite positioning errors represents a substantial step towards the Global Navigation Satellite System (GNSS) performance assessment. Satellite positioning accuracy in the particular area can be expected to be similar due to prevailing environmental conditions. This similarity opens the opportunity to estimate and predict the positioning errors of close locations. The paper aims to develop a regional model of positioning errors estimation for Global Positioning System (GPS) single-frequency receivers based on ground truth data from reference stations, in this phase considering different levels of space weather activity as one f the criteria defining environmental conditions. The model should provide a simple positioning error prediction in cases where reference stations and respective data do not exist. The space weather conditions were examined to determine the influence on GPS satellite positioning performance at three selected International GNSS Service (IGS) stations in the Adriatic Region - Graz, Padua, and Matera. The mutual relations in terms of positioning error patterns were elaborated. The same 15-day period in three consecutive years was analysed. Pearson’s coefficient was utilised as a major indicator for determining the degree of correlation. The data from IGS stations Padua and Graz showed better, significant correlation results. The IGS station Matera, located farther and southward slightly differed in positioning deviations’ patterns and was not used for the model development. Satellite positioning errors of IGS Padua were used as a reference to determine the positioning errors of IGS Graz. Due to the significant correlation results, the linear regression model has been developed for the latitude, longitude, and height positioning errors. The final model coefficients were calculated as average values of the model coefficients for latitude, longitude, and height errors for elaborated periods. The cross-validation with five folds has been carried out, showing good model performance with R2 values of 0.7785 for geographic latitude, 0.8132 for the geographic longitude, and 0.7796 for height above sea level, respectively. The validation showed that the model could be applied during all levels of space weather activity on a regional basis