Repository of the University of Rijeka, Faculty of Maritime Studies
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Behaviour of welded additively manufactured steel AISI 316L in the marine environment
No full textU ovom završnom radu obrađene su tri cjeline. Prvi dio je upoznavanje sa korozijom, u tom je dijelu razjašnjena teorija korozije, njezin utjecaj na ekonomiju, navedene su osnovne podjele korozije te se spominje kako se korozija proučavala kroz povijest. U drugom dijelu se dotakla tema o aditivnoj proizvodnji nehrđajućih čelika sa novijom tehnologijom uz pomoć 3D printanja. Opisano je kako korozija utječe na ovakvu vrstu materijala proizvedenom 3D printanom tehnologijom. Postavljeno je pitanje da li bi tako proizveden materijal mogao biti konkurentan u pomorskoj industriji istom materijalu koji proizveden tradicionalnom metodom. U trećem dijelu prikazan je obavljeni eksperiment gdje su ispitane mehaničke karakteristike nehrđajućeg čelika AISI 316 L dobivenog na oba načina te izloženog utjecaju morskog okoliša. Rezultati dobivenih ovakvim eksperimentima mogu biti značajni za razvoj i unaprjeđenje pomorske industrije.This thesis consists of three main sections. The first section is an introduction to corrosion, in that part corrosion theory is covered and how it affects the economy, the basic division of corrosion is listed, and how corrosion has been studied throughout history. In the second section, the topic of additive manufacturing of stainless steel is touched upon. It is described how corrosion affects this type of material produced by 3D printed technology. The question was raised whether the material produced in this way could be competitive in the maritime industry with the same material produced by the traditional method. In the third section, an experiment was conducted where the mechanical characteristics of AISI 316 L stainless steel obtained in both ways were tested after the exposure to marine enviroment. These types of experiments can be significant for the development and improvement of the maritime industry
Simulation Approach as an Educational Tool for Comparing NOx Emission Reductions in Two-Stroke Marine Diesel Engines During Low-Load Operation: Water–Fuel Emulsion vs. Late Injection
No full textShipping, as the most efficient, cheapest, and most widespread mode of transporting goods, also generates significant exhaust emissions. This has led to the adoption of stringent regulatory restrictions on emissions from ship propulsion systems. Consequently, the education and training of marine engineers can significantly impact their understanding of how emissions are generated and their potential for reduction. The engine room simulator is an indispensable tool in the training of marine engineers. Since operating conditions and parameters have the greatest impact on NOx emissions, this forms the primary focus of this research. This study tests the accuracy and precision of the engine room simulator in simulating emissions and evaluating the influence of operating conditions on them. Furthermore, the implementation and testing of NOx emission reduction technologies are vital for promoting sustainable shipping, ensuring regulatory compliance, and training personnel to support environmentally conscious maritime operations. Using the example of a two-stroke marine diesel engine, the results obtained are compared with test bench data from similar engines. Special emphasis is placed on simulating the operation of a two-stroke diesel engine at low speed, or low load, where secondary NOx reduction methods cannot be used. Therefore, the simulator is tested using two available technologies: water–fuel emulsion and altering the fuel injection timing to reduce NOx emissions. The simulation results for the water–fuel emulsion show high accuracy in predicting NOx emission trends when changing the water content in the emulsion at nominal power. However, at low load, the results show significant deviations. Testing the effect of altering fuel injection timing under low load using the engine room simulator shows significant differences compared to available research. Nonetheless, research on NOx emissions in this engine mode is limited, presenting a potential area for further study. When comparing the results for nominal power operation, the simulation provides more accurate results, particularly in terms of the influence of fuel injection timing on NOx emissions. However, engine tests on the test bench still reveal more substantial changes in emissions than those obtained using the engine room simulator
The Impact of Human Factors on Safety at Railway- Road Crossings in the Western Part of Croatia
No full textRailway-road crossings over rail tracks are intersections of two separate transportation systems
that, from a safety standpoint, represent a high-risk point for all traffic participants. In the absence of
adequate levels of protection at railway-road crossings, the danger significantly increases, as evidenced
by the number of traffic accidents occurring at these locations. The subject of research in this paper
is the impact of the human factor on safety at railway-road crossings in the Western Region, which
encompasses the areas of Karlovac County, Lika-Senj County, Primorje-Gorski Kotar County, and
Istria County. The aim of this study is to determine the safety conditions at railway-road crossings in
the Western Region and compare them with the rest of the Republic of Croatia. Subsequently, the goal
is to ascertain the extent of the human factor’s influence on their occurrence. The working hypothesis
states that accidents resulting in fatalities occur at railway-road crossings with low railway and road
traffic on county, local, and unclassified roads in or near settlements because drivers fail to comply
with regulations. To support the hypothesis, the study utilized scientific methods such as analysis and
synthesis, descriptive method, induction and deduction method, and comparative method. The research
results are based on secondary sources of data for the period from 2014 to 2023
Exploring the Perceived Ease of Use of an Immersive VR Engine Room Simulator among Maritime Students: A Segmentation Approach
No full textThe integration of innovative technologies, such as Virtual Reality (VR), into maritime education presents a substantial challenge but also offers significant potential for enhancing training and knowledge transmission. This study aims to contribute to the existing body of knowledge by providing segmented insights into maritime students’ Perceived Ease of Use (PEU) of an immersive engine room VR simulator. The study analysed a sample of 58 students from the Faculty of Maritime Studies at the University of Rijeka, covering undergraduate, graduate, and specialized maritime education programs. Through hierarchical and non-hierarchical cluster analyses, two distinct segments were identified and named Proactivists and Moderates. The findings reveal significant differences between extracted sub-groups regarding (i) perceived benefits of using the VR engine room simulator in learning and education, (ii) future intention to use the technology, and (iii) overall experience. Study insights can directly aid educators and software developers in enhancing the further implementation of VR technology in maritime education
Optimization of CART Models Using Metaheuristics for Predicting Peach Firmness
No full textThe current advancements in the field of machine learning can have an important application in agriculture and global food security. Machine learning has considerable potential in establishing knowledge-based farming systems. One of the main challenges of data-driven agriculture is to minimize food waste and establish more sustainable farming systems. The prediction of the right harvest time is one of the ways to obtain the mentioned goals. This paper describes multiple machine learning algorithms that are used to predict peach firmness. By accurately predicting peach firmness based on various peach measurement data, a more precise harvest time can be obtained. The evaluation of nature-inspired metaheuristic optimization algorithms in enhancing machine learning model accuracy is the primary objective of this paper. The possibility of improving the peach firmness prediction accuracy of regression tree models using various metaheuristic optimization techniques implemented in GA and metaheuristicOpt R packages is studied. The RMSE on test data of the default regression tree model is 1.722285, while the regression tree model optimized using the gray wolf optimization algorithm scored the lowest RMSE of 1.570924. The obtained results show that it is possible to improve the peach firmness prediction accuracy of the regression tree model by 8.8% using the described method
Influence of fatigue on the engine crew
No full textOvaj rad istražuje utjecaj umora na posadu stroja na brodu s ciljem osvjetljavanja kako
umor utječe na sigurnost, učinkovitost i operativnu pouzdanost u pomorskom sektoru.
Analizirat će se uzroke umora, kao što su dugi radni sati, nepravilni rasporedi spavanja i
izazovni uvjeti rada na brodu. Kroz detaljnu analizu i primjere iz prakse, rad će pokazati kako
umor može oslabiti sposobnost posade stroja da donosi ispravne odluke, održava koncentraciju
i reagira na hitne situacije.
Kroz ovaj rad, nastoji se pridonijeti boljem razumijevanju problema umora u pomorskoj
industriji i naglasiti važnost implementacije preventivnih mjera za upravljanje umorom.
Također, želi se potaknuti razvoj politika i praksi koje će poboljšati radne uvjete na brodu,
smanjiti rizik od nesreća i kvarova, te dugoročno povećati sigurnost i učinkovitost pomorskih
operacija. Rad će poslužiti kao vodič za donositelje odluka, istraživače i praktičare u industriji,
s ciljem izgradnje bolje i sigurnije budućnosti za posadu stroja.This research examines the impact of fatigue on the engine crew aboard ships with the aim of highlighting how fatigue affects safety, efficiency, and operational reliability in the maritime sector. The causes of fatigue will be analyzed, such as long working hours, irregular sleep schedules, and challenging working conditions on board. Through detailed analysis and practical examples, the paper will demonstrate how fatigue can weaken the engine crew's ability to make correct decisions, maintain concentration, and respond to emergency situations. This paper aims to contribute to a better understanding of the issue of fatigue in the maritime industry and emphasize the importance of implementing preventive measures for fatigue management. It also seeks to encourage the development of policies and practices that will improve working conditions on board, reduce the risk of accidents and equipment failures, and, in the long term, enhance the safety and efficiency of maritime operations. The paper will serve as a guide for decision-makers, researchers, and industry practitioners, with the goal of building a better and safer future for engine crew
Maritime English Corpus
No full textThe Maritime English Corpus is a collection of texts covering various sub-varieties of maritime English, such as marine engineering, maritime law, etc.The corpus contains approx. 10 M tokens. The corpus has been compiled manually and using web crawling. It can be uploaded to any corpus processing tool, annotated and used for linguistic queries. The corpus will serve as a linguistic resource for the compilation of the bilingual dictionary English-Croatian Dictionary of Gas Carrier Terminology (https://www.lexonomy.eu/#/ENCROGASTERM)
Logistics operators
No full text.U ovom završnom radu istražena su ključna područja i izazovi s kojima se susreću logistički operatori u današnjem poslovanju. Fokus je stavljen na analizu ključnih aspekata logističkih operatora, uključujući transport, skladištenje, upravljanje zalihama i distribuciju. Također su obrađena pitanja tehnoloških inovacija, te pitanja održivosti i prilagodljivosti. Naglasak se stavlja na izazove s kojima se logistički operatori suočavaju kao što su rastući ekološki zahtjevi, potreba za smanjenjem troškova i povećanje brzine isporuke. Razmatraju se strategije kako bi ostali konkurentni na tržištu. Kroz analizu studija slučaja, rad prikazuje konkretne primjene logističkih operatora u različitim kompanijama.This final project explores the key areas and challenges faced by logistics operators in today's business environment. The focus is on analysing the essential aspects of logistics operators, including transportation, warehousing, inventory management, and distribution. Attention is also given to issues of tehnological innovations, sustainability, and adaptability. The emphasis is on a challenge such as growing environmental demands, the need for cost reduction, and increasing delivery speed. Strategies to remain competitive in the market are also discussed. Through case study analysis, the project shows specific applications of logistics operator in various companies
Inland waterways with focusing on port of Vukovar
No full textUnutarnji plovni putevi su od posebnog značaja za razvoj gospodarstva Republike Hrvatske. Pravnim regulativama se nastoji omogućiti lakše razvijanje riječnih sustava u Hrvatskoj, a razvojnim planovima poboljšati rad riječnih luka. Također se radi na poboljšanju informacijskih tehnologija koje će pripomoći razvijanju riječnih sustava. Nužno je poboljšati povezanost riječnih luka s ostalim vrstama prometa. U Hrvatskoj, mrežu unutarnjih plovnih putova čine Drava, Dunav, Sava i Kupa. Glavne luke su četiri; luka u Sisku, Slavonskom Brodu, Osijeku i luka u Vukovaru koja je najrazvijenija te posjeduje najveći potencijal. Ukupna duljina plovnih putova u RH iznosi 804,1 km. Luka Vukovar raspolaže s najvećim kapacitetima kad se radi o riječnom prometu u Hrvatskoj te se luka neprestano razvija i traži rješenja kojima će se poboljšati rad luke.Inland waterways are very important for future of economy of Republic Croatia. Legal regulations aim to facilitate the development of river systems in Croatia. Master plans are trying to improve the operations of river ports. Also, specialists are working on improving information technologies that will help to develop river systems. It is necessary to improve the connection of river ports with other types of traffic. In Croatia, it is possible to navigate with four Rivers, Drava, Dunav, Sava and Kupa. There are four main ports: Port of Vukovar, Port of Sisak, Port of Slavonski Brod and Port of Vukovar. Port of Vukovar is the port with biggest capacity in inland traffic of Croatia and it is necessary to improve port's technology
Topology optimization of the mount for an electric outboard motor of a competition vessel
No full textOvaj rad obrađuje dizajn i optimizaciju prihvata motora za natjecateljsko plovilo koje sudjeluje u Energy klasi međunarodnog natjecanja plovila pod organizacijom Yacht Club de Monaco. Fokus istraživanja je na smanjenju mase prihvata motora uz održavanje njegove strukturne čvrstoće kako bi se poboljšale performanse plovila. Korištenjem numeričkih metoda, posebno metode konačnih elemenata (MKE) i strukturne optimizacije u programu ANSYS, provedena je detaljna analiza naprezanja i deformacija pod zadanim opterećenjima. Optimizirani dizajn postigao je smanjenje mase od 50,58 % s minimalnim utjecajem na strukturnu izvedbu, čime je potvrđena početna hipoteza. Ovaj rad naglašava važnost naprednih inženjerskih tehnika optimizacije u postizanju održivih i visokih performansi u dizajnu pomorskih sustava.This paper discusses the design and optimization of a motor mount for a competition vessel participating in the Energy Class of an international vessel competition organized by Yacht Club de Monaco. The focus is on reducing the motor mount's weight while maintaining its structural integrity to improve the vessel's performance. Using numerical methods, particularly the Finite Element Method (FEM) and structural optimization in ANSYS, the study presents a detailed analysis of stress and deformation under given loads. The optimized design achieved a 50,58% weight reduction with minimal impact on structural performance, demonstrating the effectiveness of the optimization process and confirming the initial hypothesis. This work highlights the importance of advanced engineering optimization techniques in achieving sustainable and high-performance maritime design solutions