Spirometry is an essential test for assessing the state of the respiratory system. It provides the measurement of the ventilation volumes and flows expressed in absolute and relative values. Among ...elite athletes, the values of ventilation parameters are usually higher than the norm; therefore the interpretation of individual results of elite athletes in relation to the general healthy population is not advisable. This study aimed to determine the respiratory characteristics of elite sailors in the Olympic Finn class, and the differences between more successful and less successful sailors according to the criterion of sport efficacy. The study included 33 sailors of the Olympic Finn class who participated at the 2015 Finn European Championship. Absolute values of spirometry parameters of elite Finn sailors (FVC-Forced-vital-capacity 5.96±0.79; FEV1-Forced-expiratory-volume-in-1-second 5.10±0.63; FEV1/FVC%-Forced-expiratory-volume-in-1-second/Forced-vital-capacity 86.10±6.38; MVV-Maximum-voluntary-ventilation 190.94±32.64) are higher than the spirometry values of most other athletes. Relative values of spirometry parameters of elite Finn sailors (FVC% 101.24±14.21; FEV1% 102.53±12.09; FEV1/FVC%% 102.00±7.94; MVV% 96.77±18.59) are within the ranges of most elite athletes. Elite sailors can be considered healthy in terms of ventilation, and sailing as a sports activity can be considered beneficial for the ventilatory function of the lungs. More successful sailors had higher mean values of absolute and relative ventilation parameters of FVC, FEV1, and MVV, whereas significant differences were determined in the variables of MVV. The differences between more successful and less successful sailors in the MVV and MVV% variables could be interpreted precisely by the state of respiratory muscles.
This paper compares the numerical results for the induced electric field, the specific absorption rate (SAR), and the corresponding temperature increase in two detailed models of the human eye. The ...first model features the human eye placed in the free space, while the second one incorporates the eye model in the realistic head model obtained from the magnetic resonance imaging (MRI) scans. The electromagnetic model is based on the hybrid FEM/BEM formulation for the biological tissue, whereas the thermal dosimetry model is based on the bioheat equation solved by using the finite element method. The preliminary analysis showed a similar distribution of the induced electric field along the pupillary axis obtained in both models, however, the numerical results for the SAR and related temperature increase showed discrepancy between the two models, which can be attributed to the high values of induced field in the corneal and scleral regions obtained in the compound eye model.
International maritime security is of paramount importance to the maritime sector, particularly seafarers. The perception and importance of maritime security have evolved and are the subject of ...ongoing analysis. The concept of maritime security is closely linked to potential threats that may pose a danger to crews, ships, or the cargoes they carry. These threats are also subject to change over time. Different types of threats can have different implications for maritime security. Currently, the greatest threats to the world merchant fleet come from pirate attacks, armed robbery, terrorism, and military operations in certain maritime regions. These threats vary in nature, frequency, and motivation in different parts of the world, and so there are certain areas that are particularly vulnerable to such threats. This paper provides an analysis of maritime security from the perspective of piracy, armed robbery, and maritime terrorism by analysing individual attacks in different regions from 2019 to 2022. Each reported attack is broken down into various characteristics. Recurring characteristics in different and unrelated attacks are observed. This results in a pattern from which specific recommendations characteristic of individual regions are derived. The recommendations are subject to the dynamics of changes in international maritime security and should be actively modified and adapted accordingly.
A hydrographic survey is a standardized procedure for collecting data for the production of nautical charts and publications. It is a lengthy and costly procedure, so the survey is carried out ...depending on the capabilities of hydrographic organizations. It is known that relatively large parts of the world's oceans are very poorly covered by hydrographic surveys. To increase the amount of data collected, the International Hydrographic Organization (IHO) has introduced the concept of crowdsourced bathymetry (CSB). Under the CSB concept, all vessels meeting certain minimum technical requirements (carrying a global navigation satellite system and a single beam echo sounder) can participate in voluntary bathymetric data collection. The paper analyzes the method of collecting bathymetric data from CSB. The depth data collected as part of the CSB are compared with official data displayed on electronic navigational charts (ENC) in the United States of America. Four sea areas were selected in which 104 depths were compared at the same positions, and categorization was also made according to the criterion of navigational importance, i.e., the category zones of confidence (CATZOC). By comparing the official depth data from the hydrographic survey with the depth data collected from public sources for the same positions, their mutual relationships were established, from which it can be concluded that the CSB data, despite its limitations, is a very valuable supplement to the existing official data.
This research paper discusses preventive protection of the marine engine against abrasive effects of the catalyst fines in fuel. The relevant facts were gathered while analysing the performance of ...the slow-speed Wärtsilä RTA engine on an Aframax tanker. The analysis comprised fuel properties, regular and extraordinary examinations of the engine, including the control and replacement of piston rings and the measurement of the liner wear rate. The research particularly focused on the top compression ring as it withstands highest loads and fastest wear. On the other side, the research involved a chemical analysis of the piston rings with the purpose of establishing their chemical properties, structure, coating thickness and micro-hardness. In addition to a number of preventive measures that can be taken on board before injecting the fuel into the combustion chamber, the selection of a piston ring’s material quality affects its wear rate to a large extent. The wear rate also depends on the catalyst fines in fuel. In practice, the piston ring of GGV type proved to be resistant to abrasive wear and its chemical properties were established through laboratory material testing.
Familiarisation is an important factor of safety on technologically advanced ships. International Safety Management Code (ISM Code) states that the Company should establish procedures to ensure the ...familiarisation process, but the exact way in which familiarisation should be carried out and the duration of the process are not determined. Familiarisation is often regarded as formality although it should not be the case at all. Non-compliance with the required familiarisation procedures and flaws in the safety system often result in human error. The latter is a major cause of numerous sea accidents. The research published has revealed that shipping companies and seafarers often fail to follow the prescribed procedures and perform familiarisation inadequately.
This research is based on a survey of Croatian and Montenegrin deck and engine officers. The survey results indicate weaknesses in the familiarisation and handover processes on board ships. Therefore, suggestions are made for enhancing the existing procedures, aiming at a more efficient familiarisation and handover, particularly aboard technologically advanced ships.
Teškoće u provođenju postupaka za održavanje pomorskih karata i navigacijskih publikacija (reambulacija u procesima hidrografskih organizacija) izravno utječu na usklađenost podataka na pomorskim ...kartama i navigacijskim publikacijama sa stvarnim stanjem u naravi. Ovaj je rad pokušaj doprinosa povećanju djelotvornosti reambulacijskih postupaka i u konačnici, višem stupnju točnosti dokumenata u izravnoj službi sigurnosti plovidbe. Predlažu se stanovite promjene u neposrednom terenskom radu koji obuhvaća akvatorij hidrografske izmjere, te u djelatnostima hidrografskih služba u izboru i obradama podataka iz reambulacija. Doprinos praksi svakako je određivanje odnosa reambulacije i hidrografske izmjere. Primjeren prostor posvećuje se razgraničenju redovitih reambulacijskih i izvanrednih postupaka.
The impact of cruise tourism on key stakeholders determines further development of the cruise industry on a destination, imposing an obligation to systematically and continuously monitor ...stakeholders’ perceptions and attitudes. During 2019, primary research was conducted to examine two keys components of the cruise activity at the destination: the impact of cruise tourism on the local population and stakeholders performing business activities in the port of Split. Two individual groups of survey questionnaires were created. Special attention was given to the social, economic, and environmental impacts of cruise tourism, respecting the principles of sustainable development. These values were estimated based on the Likert scale. The local population considers the economic and social effects of cruise tourism as exceedingly positive and is more prepared for tolerance and resilience to achieve the expected well-being. Local business stakeholders are more restrained and record a minimal increase in income and employment related to the cruise activity. Limited perception and knowledge on sustainable development in the port of Split are characteristic of both groups of respondents.
Položaj zapovjednika broda u suvremenim radnim uvjetima iznimno je složen i otežan. Za sigurnu realizaciju pomorskog pothvata i za puno pridržavanje odgovarajućih pravila i propisa odgovoran je ...zapovjednik broda. S druge strane, on je zaposlenik brodara i, sukladno tome, mora štititi njegove interese, koji ne samo što nisu uvijek u skladu s propisanim normama, nego su nekad i u sukobu sa zahtjevanim stupnjem sigurnosti. To u konačnici rezultira upletanjem brodara u one zapovjednikove odluke na koje inače ne bi smio utjecati. Pa iako je konačna procjena sigurnosti i djelovanje u skladu s tom procjenom posvemašnja obveza zapovjednika, zbog upletanja brodara današnji je stupanj sigurnosti pomorskog prijevoza znatno ugrožen. U ovom se radu upravo istražuje utjecaj brodara na navigacijske i slične poslove što ih obavljaju zapovjednik broda i časnik palube.
The position of the master nowadays is extremely complex and demanding. The master is responsible for successful completion of the voyage and to make sure all the rules and regulations are strictly followed at all times. On the other hand, the master is an employee of the shipping company, therefore, he is expected to protect the interests of his employer. The interests of the shipping company are not always in accordance with the rules and regulations. There are occasions when these interests are in conflict with the required degree of safety, resulting in a negative impact on the master’s decisions. Although the ultimate safety assessment and relevant action lies with the master, due to the ship owners’ interference in the master’s decisions the safety level in maritime transport nowadays has been significantly reduced. This paper explores the impact of shipping company on navigational and related duties performed by the master and deck officers.
U radu je razmatran pokretni autonomni podvodni objekt. Podvodni autonomni objekti su kompleksni dinamički sustavi upravljani računalima ugrađenim u njima s kompleksnim algoritmima upravljanja. ...Upravljanje takvim objektima je veoma zahtjevno, posebice zbog teških uvjeta okruženja (valovi, struje i sl.). Temelj općeg matematičkog modela objekta čini analiza uvjeta i energetskog balansa objekta pri gibanju u moru. Na bazi toga prepoznate su sve utjecajne hidrodinamičke sile i njihovi momenti koji djeluju na objekt u gibanju, pri čemu su korišteni zakoni hidrodinamike podvodnog objekta u moru za dobivanje matematičkog modela u dinamičkim uvjetima. Definiranjem koordinatnih sustava omogućeno je da se položaj objekta u svakom momentu jednoznačno određuje. Ovako definiran opći matematički model pripremljen je za rješavanje problema upravljanja pomoću računala i odgovarajućih upravljačkih algoritama.
In this paper an autonomous moving underwater object was considered. Underwater autonomous moving objects are very complex dynamic systems controlled with computers using complex control algorithms. Controlling such dynamic objects is very demanded specially regarding environmental conditions (water waves, currents and so on). On this basis, all hydrodynamic forces and their torques acting to the moving object were identified. The position of the object was unambiguously determined in any time instance by defining coordinate systems. On the basis of known relations of hydrodynamics and system energetic balances, self-mobile underwater object and water, the general mathematical model of dynamics of underwater object is reached. General mathematical model defined in this way is prepared for computer algorithm of object control.
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