VATRODOJAVNI SUSTAVI NA BRODU

Vatrodojavni sustav može odigrati presudnu ulogu u spašavanju ljudi i broda samo ako pouzdano i brzo dojavi točnu lokaciju nastanka požara na brodu. Osim toga vatrodojavni sustav mora automatski poduzeti niz akcija kako bi se spiječilo širenje nastalog požara i omogućila evakuacija ljudi iz ugroženog dijela broda, kao što je zatvaranje protupožamih vrata, uključivanje sustava za gašenje požara, isključivanje ventilacijskog sustava i slično. To se može postići jedino praVIlnim izborom odgovarajućeg vatrodojavnog sustava i vatrodojavnih detektora za određeni tip broda. U članku se analiziraju mogućnosti, prednosti i mane pojedinih tipova vatrodojavnih sustava na suvremenim brodovima

Historical Development of Fire Detection System Technology on Ships

Early fire detection has a crucial role in fire spreading and extinguishing. Development of fire detection technology was introduced as a result of series of great fire incidents, which have caused heavy material losses with even greater casualties. Fire is among the major sources of danger to the ship, and therefore special attention must be paid to preventing and extinguishing fires on board. The recent development of fire detection sensors and their integration into the fire alarm system can be traced through the development of four generations of sensors. Integration of fire detection technology with microelectronics and information technologies, a high level of system autonomy is achieved, allowing wireless networking of fire alarm sensor while increasing system reliability and availability

NMEA Communication Standard for Shipboard Data Architecture

The paper describes a computer network of an integrated navigation system on board the ship using NMEA 2000 standard, which is primarily designed to provide two way communication between the ship’s navigational equipment such as radar, GPS receiver, AIS, Gyro compass etc. NMEA 2000 is based on CAN which is standardised by ISO. ISO 11898 specifi es physical and datalink layer of serial communication technology called Controller Area Network that supports distributed real-time control and multiplexing. This paper presents a comparison of the NMEA 2000, which is based on CAN, with popular Ethernet protocol, which is currently used as a basic protocol in the LAN. The physical, datalink and application levels of the NMEA 2000 computer network are described. Finally, the marine electronic equipment of modern ship which is integrated in navigational system using NMEA 2000 is shown. NMEA 2000 standard became international standard under IEC

Algoritam za sprječavanje zastoja temeljen na uzastopnoj kontroli sifona Petrijeve mreže

This paper presents a formal calculation method of a deadlock prevention supervisor by the use of Petri nets. The proposed algorithm uses reachability tree to detect deadlock state and iterative siphon control method to synthesize the deadlock prevention supervisor. Such supervisor is maximally permissive and consists of minimal number of control places. The algorithm is intended for reversible or partially reversible P-T Petri net, but it can also be applied to Ordinary Petri nets. The calculation of the supervisor is illustrated by two examples. The first example shows the synthesis of deadlock prevention supervisor in a manufacturing system consisting of three conveyors and three robots, where the deadlock can occur due to concurrent requests of the conveyors for the robot engagements and unpredictable duration of those engagements. The second example shows the synthesis of deadlock prevention supervisor in a marine traffic system, where dangerous vessel deadlock situations may occur in case of vessels\u27 irregular motion through the system. To avoid this, the vessel traffic is supervised and controlled by traffic lights using the deadlock prevention supervisor, which is responsible for vessels\u27 stopping only in the case of dangerous situation and until this situation elapses.Članak opisuje formalnu metodu proračuna nadzornika za sprječavanje zastoja korištenjem Petrijevih mreža. Predloženi algoritam koristi stablo dostupnih stanja za detekciju stanja zastoja i metodu uzastopne kontrole sifona za sintezu nadzornika za sprječavanje zastoja. Nadzornik je najviše dopuštajući i sadrži najmanji broj kontrolnih mjesta. Algoritam je namijenjen za reverzibilne ili djelomično reverzibilne P-T Petrijeve mreže, ali se može koristiti i za obične Petrijeve mreže. Proračun nadzornika pokazan je na dva primjera. Prvi primjer prikazuje sintezu nadzornika za sprječavanje zastoja u fleksibilnom proizvodnom sustavu s tri robota i tri proizvodne trake, gdje se zastoj može dogoditi zbog međusobnog natjecanja transportnih traka za angažiranjem robota te zbog nepredvidljivosti trajanja tih angažmana. Drugi primjer prikazuje sintezu nadzornika u pomorskom prometnom sustavu, gdje se opasne situacije zastoja plovila mogu dogoditi poradi neodgovarajućeg pomicanja plovila kroz sustav. Da bi se to izbjeglo, promet plovila se nadzire i upravlja pomoću svjetlosne signalizacije korištenjem nadzornika za sprječavanje zastoja, koji je odgovoran za zaustavljanje plovila samo u slučaju opasnog stanja te dok to stanje ne nestane

Samoorganiziranje u autonomnoj arhitekturi za pružanje diferenciranih usluga primjenom algoritma za balansiranje prometa

This paper is about the role of a heuristic algorithm for load balancing that can be incorporated in Multi-Protocol Label Switching/ Differentiated Services (MPLS/DS) networks based on self-management principles for automated traffic configuration. Delivery of Quality of Services (QoS) differentiation according to specific service level agreements, Service Level Agreement (SLA), has to be in relation to resource management and bandwidth allocation, to ensure better end-to-end QoS provisioning and to avoid traffic congestion. To ensure simultaneous traffic flows with different priorities we need some load-balancing procedure. It could start much earlier than usual, possibly during SLA negotiation. If SLA creation is supported by load control mechanism it can ensure better performances of the network in the moment of service invocation. LSP (Label Switching Path) creation could be influenced by former contracted SLAs and such approach could be more effective than pure routing technique based on the shortest path algorithm (LSP creation in the moment of service invocation). So we propose application of heuristic algorithm tested on numerical examples with maximum M routers on the path and with differentiation of N service classes. Further, we introduced some capacity state restrictions in the process of network optimization, considering different algorithm options. We compared their performances, especially the algorithm complexity that is very important for efficient load control in huge networks.Članak opisuje ulogu heurističkog algoritma za balansiranje opterećenja i dimenzioniranje prometa u MPLS/DiffServ mreži na načelu samoorganizacije i automatske konfiguracije. Ostvarenje QoS usluga mora biti u skladu s postojećim ugovorom za kvalitetu usluge (SLA), sklopljenim između korisnika i operatera, ali tako da se omogući upravljanje resursima mreže izbjegavajući moguća zagušenja. Da bi osigurali simultane prometne tokove uz razlikovanje kvalitativne razine, nužno je osigurati balansiranje prometa. Takvo balansiranje mreže može započeti i znatno ranije, moguće već u trenutku pregovaranja pri sklapanju SLA. Ako je ono podržano kontrolom mogućeg zagušenja mogu se značajno poboljšati QoS jamstva i uravnoteženost mreže. Kreiranje LSP puta s obzirom na prijašnje ugovoren (rezerviran) promet bilo bi bolje od samog usmjeravanja na načelu najkraćeg puta (usmjeravanje u trenutku pokretanja usluge). Za tu je namjenu u radu predložena primjena heurističkog algoritma testiranog na mnogim numeričkim primjerima s maksimalno M usmjerivača na putu s kraja-na kraj domene i s maksimalno tri vrste (N=3) različitih kvalitativnih razina (klase prometa). Razmatrana su daljnja poboljšanja algoritma u ograničavanju stanja kapacitivnih točaka u postupku mrežne optimizacije, tj. testirane su i uspoređene razne opcije algoritma. Neke od njih pokazuju značajno smanjenje složenosti uz zadovoljavajuću kvalitetu ostvarenih rezultata, što je važno za kontrolu opterećenja u velikim mrežama

Modeliranje i simuliranje piratskih napada uz pomoć hibridnih vremenskih Petrijevih mreža

U nastojanju da se poduzmu učinkovite mjere protiv piratskih napada pokazala se potreba za izradom modela koji će pridonijeti povećanju zaštite od piratskih napada na brodove u područjima gdje postoji visok rizik od te opasnosti. Zato je korištenjem hibridnih vremenskih Petrijevih mreža izrađenasimulacija vremenske dinamike piratskog napada na brod u plovidbi. U simulaciji vremenske dinamike događanja tijekom piratskog napada – studija slučaja (CaseStudy) – korištenjem Petrijevih mreža razvijeni su, prikazani i analizirani najnepovoljniji piratski napadi na brod u plovidbi uz dodatnu zaštitu ratnog broda s helikopterom. Izrađena su i analizirana tri scenarija napada pirata na brod s jednim, dva i tri piratska broda. Ovakavje sustav u svojojprirodi vrlo složen. Sastoji se od kontinuiranog dijela (Continous Systems), tj. gibanja napadnutog broda, gibanja piratskog broda i gibanja vojnog broda/helikoptera (promjena brzine, udaljenosti), i diskretnog dijela (DiscreteEvent Systems), tj. početak napada, slanje distressa. Analizirani su čimbenici koji utječu na sigurnost plovidbe broda kroz područje povećanog rizika od mogućih piratskih napada. Navedeni su karakteristični pokazatelji i istraženi načini poboljšanja sigurnosti kako bi se na kraju pokazalo darazvijena primjena vremenske dinamike piratskog napada vodi k optimalnom rješenju planiranja plovidbe broda kroz piratska područja

Buffer Time Optimization in the Function of Timetable Stability

Timetable stability depends on the regularity of trains. Any deviation from the planned timetable leads to its instability. Railway network characteristics determine the capacities of the transport service. Depending on the capacity calculation method, time components are added to the minimum headway to ensure timetable stability. The UIC 405 method is simple and can be used on all railways. The disadvantage is that the calculations are based on average data. According to the method, the minimum headway consists of the time of the average headway interval, additional time and the buffer time. The additional time is precisely defined by the number of APB sections, while the buffer time is in the average value. When creating the timetable, the goal is optimal utilisation of the infrastructure. If the headway is too long, the capacity is not used, and if it is too short, timetable instability will ensue. Instead of averaging, this work calculates a buffer time that depends on the ratio of the travel time of the previous and the following trains. In this way, the headway is optimised and the calculation of the UIC 405 method is improved

BRI Project: Are There Alternatives?

This paper discusses the problems associated with the implementation of the Belt and Road Initiative (BRI) project. The investments of the Chinese government and individual companies in project implementation have been analyzed, and alternatives, namely TRACECA, IMEC, and the Trans-Saharan Road Corridor routes, studied