A breakwater is a coastal building that aims to break up or withstand wave energy that enters the beach so that the characteristics of the incoming waves are by calculations and can reduce abrasion ...on the shoreline. Designing a floating breakwater is very complicated because it depends on many aspects. These fundamental aspects depend on each other, so if one of these aspects changes, the integrity of the floating breakwater structure will also change. One of these aspects is the magnitude of the transmission and reflection coefficients generated by the floating breakwater. This research will study the hydrodynamic performance of floating breakwater due to variations in slope and porosity in reducing and reflecting waves with computational fluid dynamics (CFD). The slope-porous floating breakwater dimension is based on previous experimental data, including a constant water depth of 0.75 m, a wave height of 0.05 - 0.125 m, and a wave period of 1.1 - 2 sec on regular waves. The results of the numerical model validation and experiments on all variations of the floating breakwater model are quite good, which is less than 10% for both wave transmission and reflection. Analysis of the influence of changes in the mooring line angle, the simulation is carried out at an angle of 30 deg to 90 deg and produces an average transmission coefficient of 0.79 and a reflection of 0.21. While the effect of changes in water level elevation (0.85 m, 0.75 m, and 0.65 m) gives a reasonably significant average transmission coefficient of 0.85 and a reflection of 0.13. The mooring line angle will be gentler at high tide, and the transmission and reflection coefficients will be higher. However, the mooring line will loosen at low tide, causing the structure to move more freely and eliminating the function of the floating breakwater itself so that the tidal phenomenon becomes a challenge for coastal experts in designing structures to produce effective and efficient hydrodynamic performance.
High-speed passenger vessels, integrated river and sea vessels, container vessels, oil tankers, and other underwater vehicles operating in maritime traffic are among the types of vessels that must be ...equipped with AIS and VHF. The safety of navigation is one of the major problems in the maritime sector, particularly in Vietnam. Furthermore, marine traffic in the seaport zone is a common and difficult issue to manage in areas with a high volume of vessel traffic, mostly in places where the infrastructure supporting navigation is inadequately developed to meet the rapidly growing demands of the contemporary world. Therefore, it is necessary to create an integrated maritime management system to improve the efficiency of data exploitation and support maritime safety. To address this challenge, this study suggests a Maritime Traffic State Prediction (MTSP) model to predict traffic conditions in the channels where real-time data collection is insufficient in some specific locations. We recommend a deep learning method using Long Short-Term Memory (LSTM) networks to predict the safe path of the vessel in case of missing data segments. The findings have shown that the proposed approach encourages the mining of historical vessel data for maritime traffic, is ready to be applied, and can easily be implemented in a computer program or a web-based app.
Statveni klizni ležaj vratilnog voda brodskog porivnog sustava u ekspolataciji stvara gubitke, javlja se trenje i dolazi do pojave trošenja materijala tribosustava. Jedan su od razloga i različiti ...režimi plovidbe broda koji imaju utjecaj na oblikovanje polja brzina na brodskom vijku. Promjenjivo polje brzina definira iznos porivne sile, ali i položaj njezina hvatišta. Metodologija dana ovim radom zasniva se na činjenici postojanja ekscentriciteta porivne sile, tj. opterećenja uslijed djelovanja momenta ekscentrične porivne sile. Zbog promjenjivog položaja hvatišta porivne sile mijenja se zakrivljenost elastične linije rukavca unutar statvenog ležaja, koja je većinom prostorna i ima utjecaja na područje rada kliznog ležaja. Stoga je i istaknuta važnost dovoljne debljine sloja maziva za podmazivanje u odnosu na te promjene. U ovom radu to predstavlja inicijalni kriterij pri odabiru materijala i maziva statvenog ležaja. Jednako važan kriterij bio bi definirati mogući štetni utjecaj curenja maziva za podmazivanje s česticama ležajnog materijala na ekosustav. Kako bi cijeli postupak bio olakšan, donosi se pojednostavljen analitički model koji će se moći koristiti u početnoj fazi odabira statvenog ležaja. Takav model omogućava lakšu analizu utjecaja elastične linije na stanje u statvenom ležaju za slučajeve opterećenja težinom brodskog vijka i momentom ekscentrične porivne sile. Procedura za početni odabir statvenog ležaja nastala ovim metodološkim pristupom mogla bi imati svoju praktičnu primjenu. Iz tog razloga u radu se analiziraju različiti režimi plovidbe i njihov utjecaj na područje rada statvenog kliznog ležaja. Dobiveni rezultati mogu biti korisni pri odabiru materijala i maziva ležajnog tribosustava.
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