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Influence of weather conditions on the quality of detection of traffic control devices by the ADAS system in vehicles
No full textPrometna signalizacija predstavlja važan infrastrukturni element u cestovnom prometu, a glavna joj je zadaća prenositi informacije sudionicima u prometu. Danas, osim ljudskim sudionicima u prometu, prometna signalizacija, naročito oznake na kolniku i prometni znakovi, informacije prenose i naprednim sustavima pomoći vozaču (engl. Advanced Driver Assistance Systems – ADAS). Svrha navedenih sustava je da prikupljajući informacije iz okoline pomažu vozaču tijekom vožnje, te na taj način doprinose povećanju sigurnosti cestovnog prometa. Za prikupljanje informacija i percepciju okoline, ADAS sustavi koriste različite senzore poput kamera, radara te lidara. Na kvalitetu detekcije navedenih senzora utječe niz faktora, a jedni od njih su i vremenski uvjeti. Naime, kiša, magla, snijeg, sunce i ostali vremenski uvjeti mogu utjecati na kvalitetu i točnost prikupljanja informacija iz okoline, a time i na detekciju oznaka na kolniku i prometnih znakova što u konačnici može negativno utjecati na pravilan rad određenih ADAS sustava. Slijedno tome, cilj ovog diplomskog rada je prikazati kako i u kojoj mjeri različiti vremenski uvjeti utječu na detekciju prometne signalizacije ADAS sustavima u vozilima. Senzori kao što su kamere pokazuju loše rezultate pri jakom bliještanju, zalasku sunca ili sumraku te bolje prepoznaju oznake na kolniku povećanjem kontrasta i retrorefleksije. U uvjetima kiše ili magle se lidarima i radarima sposobnost detekcije smanjuje zbog slabljenja intenziteta primljenog signala.Traffic control devices are important road infrastructural elements, and their main task is to transfer information to road users. Today, except to humans, traffic control devices, especially road markings and road signs, convey information to Advanced Driver Assistance Systems (ADAS). The purpose of those systems is to collect information from the environment and based on that information assist the driver, thus contributing to increase of road safety. To collect information and perceive the environment, ADAS systems use various sensors such as cameras, radars and lidars. The detection quality of the mentioned sensors is affected by a number of factors, one of which are weather conditions. Namely, rain, fog, snow, sun and other weather conditions can affect the quality and accuracy of gathering information from the environment, and with that the detection of road markings and traffic signs, which can ultimately negatively affect the proper operation of certain ADAS systems. In addition, the goal of this master thesis is to show how and in what extent different weather conditions affect detection of traffic signaling. Sensors such as cameras have significantly lower detection rate when there is high sun glow, sunset or dawn and perform better when there is higher contrast and retroreflection. With radars and lidars rate of detection is lower in conditions of rain and fog due to lower intensity of received signal
Aerodynamic Characteristics of Gas Flow Through a Supersonic Nozzle
No full textZa ubrzanje struje fluida sa podzvučne na nadzvučnu brzinu koristi se konvergentno-divergentna mlaznica. Takve vrste mlaznica prisutne su u raketnim motorima ili motorima nadzvučnih vojnih mlaznih zrakoplova. Definirano je i opisano kvazi-jednodimenzionalno strujanje koje je prigodno za razmatranje karakteristika strujanja kroz nadzvučnu mlaznicu i nadzvučne difuzore. Nakon definiranja osnova strujanja fluida kroz nadzvučnu mlaznicu i difuzor, definiran je model nadzvučne mlaznice korišten pri CFD analizi aerodinamičkih karakteristika strujanja plina. Dizajn nadzvučne mlaznice opisan je metodom karakteristika. Također, metoda karakteristika je opisana ukratko kao odličan alat pri izračunu kontura zidova nadzvučne mlaznice. Mlaznica koja je dizajnirana i korištena u radu spada pod vrstu mlaznica minimalnih duljina. Za kraj prikazani su rezultati CFD analiza strujanja u slučaju viskoznog i neviskoznog strujanja. Pojava graničnog sloja se lijepo vidi pri viskoznom strujanju, te porast temperature u blizini zidova mlaznica uslijed pojave trenja. Prikazan je i slučaj pojave normalnog udarnog vala unutar mlaznice. Rezultati su validirani pomoću metode karakteristika.A convergent-divergent nozzle is used to accelerate the fluid flow from subsonic to supersonic speeds. Such types of nozzles are present in rocket engines or supersonic military jet aircraft. A quasi-one-dimensional flow is defined and described, which is convenient for considering the characteristics of flow through a supersonic nozzle and supersonic diffusers. After defining the basis of the fluid flow through the supersonic nozzle and the diffuser, the model of the supersonic nozzle used in the CFD analysis of the aerodynamic characteristics of the gas flow was defined. The design of the supersonic nozzle is described by the method of characteristics. Also, the method of characteristics is briefly described as an excellent tool for calculating the contours of supersonic nozzle walls. The nozzle that was designed and used in the work belongs to the category of minimum length nozzles. Finally, the results of the CFD flow analysis in the case of viscous and non-viscous flow are presented. The appearance of the boundary layer is visible during viscous flow, and the increase in temperature near the walls of the nozzles due to the appearance of friction.. Results are validated by the method of characteristics
Cold Chain Warehouse Process Optimization
No full textOptimizacija skladišta je proces, koji pomaže riješiti mnoge probleme i ostavlja skladište bez problema. Uz optimiziranje svih procesa koji se odvijaju unutar skladišta, izgledno je očekivati bolje rezultate i zadovoljnije kupce. Da bi se neki određeni sustav optimizirao bitno je poznavati sve procese u tom sustavu te svaki zasebno analizirati kako bi smo uočiti moguća poboljšanja. U skladištima gdje procesi nisu optimalno postavljeni, nerijetko dolazi do problema kao što su učestale greške, kašnjenje robe u otpremi, akumuliraju se previsoki troškovi i razina usluge nije zadovoljavajuća. Optimizacija ili poboljšanje rada skladišta u posebnom temperaturnom režimu i istovremeno smanjenje njegovih troškova veliki je izazov za svakog voditelja skladišta. Svrha i cilj ovog diplomskog rada biti će upravo prikazati sve procese u skladišnom poslovanju u posebnom temperaturnom režimu te potencijalne načine kako unaprijediti rad u skladištu i poboljšati učinkovitost radnika.Warehouse optimization is a process, which helps to solve many problems and leaves the warehouse without problems. With the optimization of all processes inside the warehouse, it is likely to expect better results and more satisfied customers. In order to optimize a particular system, it is important to know all the processes in that system and to analyze each one separately in order to be able to see possible improvements. In warehouses where the processes are not optimally set up, problems often occur such as frequent errors, delays of the shipment departure, excessive costs accumulate and the level of service is not satisfactory. Optimizing or improving warehouse operations in temperature-controlled conditions and simultaneously reducing its costs is a big challenge for every warehouse manager. The purpose and goal of this thesis will be to show all the processes in warehouse business in a temperature-controlled conditions and potential ways to improve work in the warehouse and improve the efficiency of workers
Risk Analysis and Assessment of Aircraft Accidents Caused by Unfavourable Weather Conditions
No full textNepovoljni meteorološki uvjeti predstavljaju veliki rizik za sigurnost leta i nastanak zrakoplovnih nesreća. U nepovoljne meteorološke uvjete ubrajaju se turbulencija, smicanje vjetra, zaleđivanje, grmljavinsko nevrijeme, itd. U pogledu kategorija zrakoplovnih nesreća, najčešće nesreće su kontrolirani let u teren, gubitak kontrole nad zrakoplovom u letu te izlijetanje zrakoplova s uzletno-sletne staze. Gledano u postotnom doprinosu, a s obzirom na meteorološke čimbenike, na kontrolirani let u teren najviše utječe smanjena vidljivost. Gubitku kontrole nad zrakoplovom u letu u najvećoj mjeri doprinose smicanje vjetra i zaleđivanje, a u pogledu izlijetanja zrakoplova s uzletno-sletne staze, najveći utjecaj imaju smicanje vjetra te grmljavinsko nevrijeme. Za prevenciju nesreća uzrokovanih nepovoljnih meteoroloških uvjetima, vaţni su edukacija pilota te brzo i točno meteorološko informiranje, a od značajne pomoći su i tehnološki sustavi poput zrakoplovnog meteorološkog radara i reaktivnog sustava za detekciju smicanja vjetra.Unfavourable weather conditions present great safety risk upon flight safety and aircraft accident occurrence. Unfavourable weather conditions are turbulence, wind shear, icing, thunderstorm, ect. By categories of aircraft accidents, most frequent accidents are controlled flight into terrain, loss of control – in flight and runway excursion. Based on percentage contribution, in case of unfavourable weather conditions, controlled flight into terrain is mostly affected by poor visibility. Loss of control – in flight is mostly affected by wind shear and icing, and runway excursion mostly by wind shear and thunderstorm. In order to mitigate risk of accidents caused by unfavourable weather conditions, pilots education, frequent and correct weather information are important, with great help by means of technologies like on-board weather radar and reactive wind-shear system
Analysis of Landing Stages for River Cruise Ships in the Republic of Croatia
No full textPutovanje brodovima za kružna putovanja na rijekama posljednjih godina bilježi sve veću stopu rasta, kako u svijetu tako i u Republici Hrvatskoj. U radu je napravljen osvrt na pristaništa za prihvat brodova za kružna putovanja na unutarnjim plovnim putovima Republike Hrvatske, i to pristaništa na rijeci Dunav: Batina, Aljmaš, Vukovar i Ilok, pristaništa Osijek na rijeci Dravi te pristaništa Sisak i Slavonski Brod na rijeci Savi. Sukladno raspoloživim podacima prikazana je analiza putničkog prometa na navedenim pristaništima. Iz rada je vidljivo kako je trenutno stanje pristaništa na rijeci Dunav i rijeci Dravi na zadovoljavajućoj razini dok na rijeci Savi glavni problem predstavlja pouzdanost plovnog puta.River cruises have seen an increasing growth rate in recent years, both globally and in the Republic of Croatia. The paper provides an overview of river cruise landing stages on inland waterways in the Republic of Croatia. The following landing stages were analysed: Batina, Aljmaš, Vukovar and Ilok on the Danube, Osijek on the Drava, and Sisak and Slavonski Brod on the Sava. Based on the available data, the analysis of passenger traffic at these landing stages is presented. The paper shows that the current condition of the landing stages on the Danube and the Drava rivers is sufficient, while on the Sava River the main problem is the reliability of the waterway
Analysis of the organizational structure of air navigation service providers
No full textDa bi se mogao uspostaviti jedan ili više pružatelj usluga u zračnoj plovidbi neke države, potrebno je ispoštovati niz procedura koje za sobom vuku brojne zakone, norme i standarde koji se trebaju poštivati prilikom uspostave i tijekom rada jednog pružatelja usluga u zračnoj plovidbi. Zakone, norme i standarde propisuje Međunarodna organizacija civilnog zrakoplovstva te osigurava da se isti poštuju u svim procedurama zrakoplovstva. U svrhu stvaranja jednakih uvjeta za sve pružatelje usluga u zračnoj plovidbi, došlo je do standardizacije usluga i procedura za obavljanje istih te su pružatelji usluga dužni davati godišnja izvješća kako bi se dobio uvid u njihovu produktivnost i rad. Pregled i analiziranje rada i produktivnosti određenih pružatelja usluga u zračnoj plovidbi omogućava usporedbu istih te potiče sve pružatelje usluga u zračnoj plovidbi da svoj rad i produktivnost redovno poboljšavaju. Jedan od bitnijih segmenata prilikom uspostavljanja pružatelja usluga u zračnoj plovidbi je jasno definiranje vlasništva tj. organizacijske strukture unutar istog. Definiranje vlasništva od velikog značaja je za određivanje krajnje odgovorne osobe za sve odluke i promjene, kao i za pitanje financija unutar organizacije.In order to establish one or more air navigation service providers in a country, it is necessary to follow a series of procedures that entail a number of laws, norms and standards that need to be followed when establishing and operating an air navigation service provider. Laws, norms and standards are prescribed by the International Civil Aviation Organization and ensured that they are respected in all aviation sector procedures. In order to create equal conditions for all air navigation service providers, standardization of services and procedures for their performance has occurred, and service providers are obliged to provide annual reports in order to gain insight into their productivity and work. Reviewing and analyzing the work and productivity of certain air navigation service providers enables comparison of the same and encourages all air navigation service providers to regularly improve their work and productivity. One of the important segments when it comes to establishing a air navigation service provider is defining ownership, i.e. organizational structure o fair navigation service provider. Defining ownership is of great importance for determination of ultimately responsible person for all decision and changes, as well as for finance inside the organization
Shipment Tracking in Freight Forwarding Operations
No full textZavršni rad opisuje vrste i primjenu sustava i tehnologija za praćenje pošiljaka u špediterskom poslovanju te njihov trenutni i potencijalni značaj za razvoj prometa općenito. Takvi sustavi omogućuju praćenje statusa pošiljaka prije, tijekom i nakon isporuke što omogućuje bolju prostornu i vremensku usklađenost među sudionicima u oprskbnom lancu. Naglasak je također na implementaciji, korištenju i ulozi sustava sljedivosti i praćenja duhanskih proizvoda čijom se primjenom smanjuje nezakonita trgovina cigaretama i ostalim duhanskim proizvodima u Europskoj uniji. Podrazumijeva primjenu tzv. TTT (eng. Tobacco Track and Trace) kodova čijim se skeniranjem bilježi kretanje duhanskih proizvoda u transportnom lancu. Naposljetku je opisana primjena sustava sljedivosti i praćenja duhanskih proizvoda u poduzeću LIDL d.o.o.The final paper describes the types and application of systems and technologies for tracking shipments in forwarding business, as well as their current and potential significance for the development of traffic in general. Such systems allow tracking the status of shipments before, during and after delivery, which enables better spatial and temporal coordination among participants in the supply chain. Emphasis is also put on the implementation, use and role of the system of traceability and monitoring of tobacco products which reduces illegal trade of cigarettes and other tobacco products in the European Union. It implies the application of the so-called TTT (Tobacco Track and Trace) codes, whose scanning records the movement of tobacco products in the transport chain. Finally, the application of the system of traceability and monitoring of tobacco products in the company LIDL d.o.o. is also described
Correlation between Wind Tunnel Data and Aircraft Flight Data
No full textEksperimentalna aerodinamika nastoji dati odgovore na problematiku strujanja fluida preko tijela. Eksperimenti se provode u aerodinamičkim tunelima na temelju izračuna postavljenih preko teorije sličnosti i strujanja. Granični slojevi predstavljaju usko područje uz konturu aeroprofila pod utjecajem viskoznih i tangencijalnih sila. Prilikom testiranja posebna pozornost obraća se na ostvarivanje što izraženije sile uzgona, uz što manje otpore. Upravljačke površine i zanimljive izvedbe kompenzacija predstavljaju znatnu korist eksperimentiranja u svrhu poboljšanja upravljivosti zrakoplova. Stabilnost zrakoplova opisana je kroz gibanja u određenom prostoru.Experimental aerodynamics strives to solve major problems surrounding fluid flow against objects. Experiments are conducted inside of wind tunnels based on calculations derived from similarity of flow theory. Boundary layers represent narrow areas close to contures of aeroprofiles under the influence of viscose and tangential forces. During tests, special focus is set onto achieving as great as possible lift, while reducing drag. Control surfaces and quite interesting solutions of compensations represent great value of commencing of experiments in regard of improving of maneuverability of aircraft. Stability of aircraft is described through set of motions in defined space
Role of Cargo-Transport Centers Within Retail Supply Chains
No full textLogistički procesi i opskrbni lanac mogu se shvatiti kao neophodni čimbenici koji su nužni za odvijanje i upravljanje maloprodajnim lancima. Jedan od tih neophodnih čimbenika u opskrbnom lancu je svakako robno-transportni centar. Robno-transportni centar je mjesto s najvećim stupnjem integracije logističkih aktivnosti, logističkih sustava, te korisnika i nositelja logističkih usluga. Robno-transportni centar je također vrlo bitan faktor u distribuciji robe i opskrbljivanju maloprodajnih dućana. Analizom uloge robno-transportnog centra na tvrtkama u Republici Hrvatskoj koje su uzete za primjer može se vidjeti koliko je robno-transportni centar bitan za poslovanje određene tvrtke, ali nije i ključan.Logistics processes and supply chain can be regarded as indispensable factors required for operation and management of retail supply chains. One of indispensable factors in the supply chain is definitely a cargo-transport centre. A cargo-transport centre is a place that has the highest level of integration of logistics operations, logistics systems, logistics users and logistics operators. A cargo-transport centre is also a very important factor in the distribution of goods and supply of retail stores. Analysis of the role of cargo-transport centres in certain companies in the Republic of Croatia that have been taken as an example, can determine the importance of cargo-transport centres for the business of a company
Aircraft Accidents and Incidents Investigation and Prevention
No full textDanašnji zračni promet karakterizira sve veća potražnja, rezultat čega su sve veća zagušenja na zračnim lukama i prometnim tokovima. Razina sigurnosti mora biti na najvećoj mogućoj razini, a ista se, između ostalog, održava korištenjem sigurnosnih sustava poput TCAS i GPWS. Iako postoje sigurnosne procedure i sustavi za sprečavanje i izbjegavanje neželjenih događaja poput zrakoplovnih nesreća i nezgoda, do njih svejedno dolazi. Nakon što se nesreća ili nezgoda dogodi, potrebno je provesti istragu zrakoplovne nesreće/nezgode prema smjernicama ICAO-a specificiranima u Dodatku 13. Najvažniji postupci u istrazi su organizacija i planiranje, aktivnosti na mjestu nesreće i obavješćivanje, nakon koje slijedi istraživanje nesreće, te naposljetku izrada završnog izvješća u kojem se nalaze sigurnosne preporuke koje služe za uvođenje promjena u svrhu poboljšanja sigurnosti zračnog prometa i prevencije budućih nesreća. Istraga zrakoplovne nesreće ne utvrđuje krivnju, već služi za utvrđivanje potrebnih aktivnosti koje je potrebno poduzeti za sprečavanje budućih nesreća.Air traffic in modern world is characterized by ever increasing demand which results in increase of congestion at airports and traffic flows. The level of safety must be at the highest level possible, and the same is maintained, among other things, by using safety systems such as TCAS and GPWS. Although there are safety procedures and systems in place to prevent and avoid adverse events such as plane crushes and accidents, they do occur. After an accident or incident occurs, an air accident/incident investigation should be conducted according to ICAO guidelines specified in Annex 13. The most important investigative procedures are organization and planning, accident site activities and notification, followed by accident investigation, and finally preparation of a final report containing safety recommendations that serve to introduce changes to improve safety and prevent future accidents. The accident investigation does not establish guilt but serves to determine necessary actions to be taken to prevent future accidents