Repository of the Faculty of Transport and Traffic Sciences
Not a member yet
3131 research outputs found
Sort by
Autonomus Drone Road Surveillance
No full textNadzor cestovnog prometa vrši se u svrhu analize prometnih podataka kako bi povećali učinkovitost i sigurnost samog prometa. Nadzor se uglavnom vrši primjenom klasične tehnologije poput stacionarnih kamera, senzora, te manualnog brojanja, ali primjenom inovativnih rješenja poput bespilotne letjelice moguće je unaprijediti i olakšati taj proces, te ukloniti mane postojećih sustava. Ovim završnim radom analizirana je potreba za zamjenom postojećih sustava usporedbom prednosti i mana između navedenog i bespilotnih letjelica. Istražene su razne primjene bespilotnih letjelica u svrhu sigurnosti prometa, nadzora i upravljanja prometom i upravljanja infrastrukturom autocesta, te su predloženi načini, oprema i sustavi koji bi omogućili automatizirani nadzor cesta bespilotnim letjelicama. Sve to popraćeno je uz analizu zakona i regulative za izvođenje letenja bespilotnim letjelicama na području Europske unije i Republike Hrvatske. Pred kraj rada izvršena je i opisana praktična primjena bespilotne letjelice u svrhu nadzora.Road traffic monitoring is performed for the purpose of analyzing traffic data in order to increase the efficiency and safety of the traffic itself. Surveillance is mainly done by applying classic technology such as stationary cameras, sensors and manual counting, but by applying innovative solutions such as drones, it is possible to improve and facilitate this process, and eliminate the shortcomings of existing systems. This final paper analyzes the need to replace existing systems by comparing the advantages and disadvantages between the existing systems and unmanned aerial vehicles. Various applications of unmanned aerial vehicles for the purpose of traffic safety, traffic control and management, and motorway infrastructure management have been investigated and ways, equipment and systems that would enable automated road surveillance by unmanned aerial vehicles have been proposed. All this was accompanied by an analysis of the laws and regulations for the performance of drones in the European Union and the Republic of Croatia. Towards the end of the work, the practical application of the unmanned aerial vehicle for the purpose of surveillance was performed and described
Features and Analysis of Video Traffic
No full textCilj je rada prikazati podjelu video aplikacija i analizirati njihove osnovne značajke. Ovim radom približeno je shvaćanje ponašanja prometa od različitih video aplikacija. Opisana je važnost video kompresije bez koje bi bilo skoro nemoguće prenijeti video sadržaj. Ovisno o vrsti komunikacije (jednosmjerna ili dvosmjerna) i određenim značajkama video aplikacija, prikazane su zahtijevane prijenosne brzine. Ovim radom analizirani su parametri kvalitete usluge (QoS) kao što su propusnost, kašnjenje, varijacija kašnjenja i gubitak paketa te zahtjevi koje svaka video usluga ima za njih. Kako bi se ta kvaliteta usluge mogla održati i kako ne bi došlo do zagušenja prometa potrebno je implementirati određene mehanizme.The goal of this work is to show video varieties and analyze the characteristics of those video applications. This work brings traffic behavior from different video aplications closer to understanding. It is describing the importance of video compression, without which it would be impossible to transmit video content. The required bandwidth is displayed, depending on the type of communication (unidirectional or bidirectional) and certain characteristics of video applications. This paper analyzes the quality of service (QoS) such as bandwidth, delay, jitter and packet loss, and the requirements that each video service has for them. In order for this quality of service to be maintained and for traffic congestion not to occur, certain mechanisms need to be implemented
Risk Analysis in Deep Sea Container Shipping
No full textKontejnerizacija je utjecala na razvoj pomorskog teretnog prometa, te je postala nezamjenjiv oblik prijevoza robe. Kontejnerizacija spaja pomorski promet s drugim oblicima prometa kao što su željeznički i cestovni promet u jedan cjeloviti transportni lanac gdje je došlo do ravnomjerne standardiziranosti tog tehnološkog procesa. Kao i u svakom poslovnom procesu dolazi do rizika koji se mogu analizirati različitim modelima, procjenjivati te na kraju i prihvatiti. Uzimajući u obzir veličinu svjetskih oceana, kompleksnost samog procesa kontejnerizacije kao i važnost pomorske trgovine, rizici u kontejnerskom prometu nisu zanemarivi te su uvelike podložni analiziranju i predviđanju istih što dovodi do toga da se traže rješenja kako bi se rizici prebrodili te naposljetku i smanjili. U ovom radu prikazani su rizici te analiza rizika u kontejnerskom prijevozu, s naglaskom na prekooceanski prijevoz kontejnera.Container shipping has influenced the development of maritime freight transport, and has become an indispensable form of transport of goods. Container shipping combines maritime transport with other forms of transport such as rail and road transport into one complete transport chain where there has been a uniform standardization of this technological process. As in every business process there are risks that can be analyzed by different models, assessed and finally accepted. Considering the size of the world's oceans, the complexity of the container shipping process and the importance of maritime trade, the risks in container shipping are not negligible and are largely subject to analysis and prediction, which leads to solutions to overcome and ultimately reduce risks
Modelling of Ground Handling Process based on EPC Diagrams
No full textProces prihvata i otpreme uključuje sve operacije koje se odvijaju između dva leta oko zrakoplova, ali i u samom zrakoplovu na stajanci. Kako bi se proces mogao izvesti bez opasnosti potrebno je poštivati operativne procedure. Analiziranje procesa prihvata i otpreme moguće je uz prethodnu izradu modela procesa. Modeliranje poslovnog procesa u radu napravljeno je programskim alatom ARIS. Modeli četiriju perspektiva spojeni su korištenjem dijagramom vođenog procesnog lanca. U radu je napravljen model procesa prihvata i otpreme zrakoplova na primjeru Međunarodne zračne luke Zagreb.The ground handling process includes all operations around and inside an airplane between two flights. During the ground handling process, it is mandatory to follow the operating procedures. Analyzing the ground handling process is possible with the prior development of a process model. The business process model in this paper was made with the ARIS software tool. The models of the four perspectives were connected using an Event-driven process chain. The paper presents a model of the ground handling process on the example of Zagreb International Airport
Analysis of Automotive Parts Distribution in E-commerce
No full textU ovom radu obrađene su glavne značajke distribucije u doba e-trgovine s naglaskom na specifičnosti distribucije i povrata auto dijelova. Pojava Internet trgovine otvorila je vrata novim mogućnostima poslovanja, a isto tako prouzročila nove izazove za logističare. To je utjecalo na razne promjene u distribuciji i preoblikovala procese koji su do tada bili znani i korišteni. Ova tema je odabrana s ciljem proučavanja uloge i značaja distribucije u e-trgovini, te analiziranja podataka u svrhu uočavanja raznih slabosti i prilika unutar segmenta auto dijelova. S time u svezi je uzet primjer iz prakse, tvrtka Inter Cars d.o.o.This paper describes the main features of distribution in the era of e-commerce with an emphasis on the specifics of distribution and return of automotive parts. The advent of Internet commerce has opened the door to new business opportunities and also caused new challenges for logistics operators. This influenced various changes in the distribution and reshaping of processes that were used till then. This topic was selected with the aim of studying the role and importance of e-commerce distribution and analyzing the data in order to identify various weaknesses and opportunities within the automotive parts segment. Regarding to this, the company Inter Cars d.o.o was taken as an example
Travel Time Prediction Model in Urban Mass Transit
No full textKvaliteta usluge u javnom prijevozu putnika utječe na održivost gradske mobilnosti. U masovnom javnom gradskom prijevozu vrijeme putovanja jedan je od najznačajnijih indikatora pouzdanosti usluge kao kategorije kvalitete usluge. No za prijevoz tramvajem, trolejbusom i autobusom karakteristične su neravnomjerna prijevozna ponuda i potražnja, uzrokujući varijabilnost vremena putovanja i slabu pouzdanost usluge za putnike. Varijabilnost je posljedica unutarnjih faktora smetnji kao što je nagomilavanje vozila, i vanjskih faktora smetnji kao što su prometni tokovi, semaforizirana raskrižja i prijevozna potražnja. Istraživanje se provelo na jednoj tramvajskoj liniji u Zagrebu, tako da se linija podijelila na segmente, za koje se utvrdilo idealno vrijeme putovanja. U istraživanju su se utvrdili odnosi između vremena putovanja i faktora smetnji, te su se kao značajni faktori smetnji pokazali semaforizirana raskrižja, idealno vrijeme putovanja i utjecaj tokova ostalih vozila, dok su se kao pogodne veličine za modeliranje pokazali medijalno vrijeme putovanja, deseti percentil i devedeseti percentil. Rezultati istraživanja pokazuju da je moguće izraditi prognostički model vremena putovanja pomoću faktora smetnji, no ne i pomoću neravnomjernosti prijevozne ponude. Na temelju validacije modela, određeno je minimalno i maksimalno vrijeme putovanja te je pokazana prihvatljivost modela prema udjelu ekstremnih vrijednosti vremena putovanja. Model se testirao za dobivanje vremena putovanja na dugačkim segmentima, te je na temelju usporedbe sa stvarnim vrijednostima utvrđena ograničenost modela za opisivanje rubnih vrijednosti vremena putovanja, no model se pokazao prihvatljivim za opisivanje srednje vrijednosti vremena putovanja. Ovo je jedno od rijetkih istraživanja koje se bavi tramvajskim prometom, s korištenjem idealnog vremena putovanja kao veličine kapaciteta i korištenjem detaljnih prometnih parametara. Na temelju rezultata istraživanja, predlažu se poboljšanja modela u smislu dobivanja detaljnijih prometnih parametara, te proširenja modeliranja na dugačke segmente, ostala razdoblja tijekom dana te manje i veće vremenske raspone promatranja.Mass public transport is the backbone of sustainable urban mobility, and it is the only transport mode with high capacity to meet transport demand in cities. Traffic system of today is characterized by an increasing private car usage because of economic prosperity for citizens and unattractive transport alternatives. In the current modal split of city trips, the increasing private car usage is putting pressure on the existing urban traffic system, and by space consumption, traffic congestion, noise pollution, air pollution and poor road safety, unnecessary external costs are generated. Public transport systems in cities worldwide experience traffic congestion and overcrowded public transport vehicles. In timetable design, there are three traditional principles: meeting transport demand, reducing stop waiting time, and avoiding vehicle crowding. Quality of service is the successfulness of public transport operations considering passengers, operator, and the local community. In the literature, service reliability is one of categories belonging to quality of service, and service reliability is defined by comparing real service to the timetables. Service reliability is traditionally demonstrated by punctuality (for each measuring point in the network, difference between the observed arrival time and timetable arrival time) and regularity (for each measuring point in the network, difference between the observed interval and timetable interval). Both punctuality and regularity are crucial for service reliability, quality of service, attractiveness of mass transit and modal split of city trips. Service reliability in mass transit can be observed in a single or multiple parts of passenger trips, and each uses time to complete – these times are walking time (from source to network, for transfers, from network to destination), stop waiting time, and time spent in vehicle (consisting of running time between stops and stop dwell time on passenger routes). Due to technical capabilities in the past, service reliability research was primarily focused on stop waiting time. But with the development of automatic vehicle location and automated passenger counting technologies, a more detailed insight was provided into time spent in vehicles. Most in-vehicle time research of today is focused on predicting stop arrival time, to provide reliable vehicle arrival times for passengers on timetables, stop information displays or smart devices. Mass public transport is characterized by high transport supply and demand, and passengers arrive to stops randomly, without considering timetables. However, in public transport conducted by trams, trolleybuses and buses, vehicle performance is limited by the infrastructure. Completely segregated corridors are less common, and transport is often limited by the external disturbance factors (not manageable by the operator) and internal disturbance factors (manageable by the operator). The external ones are transport demand, signalized intersections, other vehicles, pedestrians, passenger behaviour and weather conditions, and the internal ones are vehicle bunching, driver behaviour, timetable quality, vehicle availability and driver availability. Because of these factors, travel time (between any two points on the line or between the terminals at maximum) is characterized by variability. Travel time variability reduces service reliability for passengers, such that their waiting time at stops and time spent in vehicles becomes more unpredictable, and they must include additional time in their trips to prevent late arrivals to their destinations. The research on travel time perception by passengers revealed that the reduction of travel time variability decreases uncertainties when estimating destination arrival time and decreases uncertainties in trip planning. Passengers also prefer reduction of variability over the reduction of average travel time itself because they can estimate arrival to the destination more precisely. Reducing travel time variability also makes transport supply more evenly distributed, reducing the number of uncomfortable rides. For the operator, less travel time variability means fewer operating costs. Travel time variability can be described by a distribution or descriptive statistics. Research has shown that distributions such as gamma, normal, log-normal, and log-logistic are most common. Normal distribution is better in commuter periods, and log-normal in non-commuter periods. The most common descriptive measures are two absolute ones (in minutes) – difference between 90th and 10th percentiles and standard deviation, and two relative ones (in percent) – ratio of 90th minus 10th percentile and median, and the coefficient of variation. Absolute measures are better for estimating time losses for passengers, and relative ones are better for estimating network performance. Research has shown that median is a better measure than the average, and that both measures increase linearly with the average travel time. Travel time is predicted by three types of models: primitive, based on data and based on traffic flow theory. The existence of many prognostic models indicates that each has advantages and disadvantages in terms of complexity, amount of input data, traffic theory, and applicability. Primitive models, consisting of instant, historical and hybrid, are easy to implement, but their disadvantage is the assumption that variables affecting travel time are constant in time. In models based on data, relationships between the dependent and the independent variables is established, so these models do not require extensive traffic theory knowledge, but they require a large amount of input data. They consist of parametric and non-parametric models. In parametric modes, two techniques are used – in time series techniques, which cannot show variations in real time, autoregressive methods are used, and in regression techniques, which may have problems with interdependence of independent variables, ridge regression, regression tree, bagging regression, random forest regression and support vector regression is often used. In non-parametric models, the relationships between variables are obtained directly from the data using machine learning – artificial neural network or support vector machine are most common. In models based on traffic flow theory, travel time is predicted using theoretical models. Unlike data-based models, these models do not require a large amount of data, but they may be inaccurate due to network specifications. They consist of macroscopic (by particle filters and Kalman filters) and microscopic (by source-destination matrices). The goal of this research is to develop a travel time prediction model for mass transit by establishing relationships between travel time and disturbance factors. The purpose of research is to improve travel time prediction in mass transit, ensuring a sustainable transport system with less external costs by shifting passengers from private cars to public transport, and reducing impact on the environment, energy consumption and space consumption. There are two research hypotheses: • hypothesis 1 – “It is possible to develop a travel time prediction model in urban mass transit based on disturbance factors” • hypothesis 2 – “It is possible to establish relationships between travel time and transport supply irregularity”. The research was conducted in five phases: • in phase 1, travel time data were collected by observing tram traffic in the city of Zagreb, by observing vehicles in specific locations on tram line 4; besides travel time data, all other data regarding distances, stops, intersections, pedestrian crossings, lane type and traffic volume were also collected • in phase 2, the collected data were processed, and the relevant measures of travel time and disturbance factors were calculated; based on the geometry, legislation and vehicle characteristics, ideal travel time was calculated • in phase 3, relationships between travel time and disturbance factors were established by correlation matrices; and insignificant variables were eliminated • in phase 4, based on correlation results, travel time prediction models using multiple linear regression were developed • in phase 5, the models were validated on a different dataset using scientific methods • in phase 6, the models were tested between the terminals, to check applicability for long segments. There were three models established by calculating three dependent variables, because all of them are important for service reliability: • deviation of median from ideal travel time – to predict travel time for average vehicle • deviation of median from the 10th percentile – to predict travel time for early vehicles • deviation of 90th percentile from ideal travel time – to predict travel time for late vehicles. After the correlation and model development, only three independent variables (predictors) remained: • traffic lights – total time lost at intersections divided by ideal travel time; total time lost at intersections is the sum of proportions of red-light times squared divided by double intersection cycle time for every intersection on the observed segment • ideal travel time – the reciprocal of ideal travel time on the observed segment was used • traffic volume – the ratio of total ideal time on sections with intense other traffic and segment ideal travel time. The model passed linear regression tests. The model was also validated by using different sample of travel time data, and the validation showed an average 9% error for 10th and 90th percentile of travel time, which was then used to estimate minimum and maximum to be used in timetables. The results showed that, by applying minimum and maximum from the validation, 10% of total vehicles will have travel time less than minimum and 14% of total vehicles will have greater travel time than maximum, which was acceptable. Therefore, the hypothesis 1 of the research was approved. Relationships between travel time and transport supply irregularity was subjected to correlation analysis as well, and several measures of supply irregularity based on vehicle interval and frequency were chosen as predictors. There were some minor correlations; however, in the multiple linear regression, all variables describing transport supply irregularity did not improve previously constructed models, and therefore the hypothesis 2 of the research was rejected. Scientific contribution of the research is achieved through: • determining disturbance factors affecting travel time in mass transit, such that the factors are richer in traffic context than in previous research • determining impact of each disturbance factor on travel time in mass transit, by introducing ideal travel time used for comparison • developing a new travel time prediction model in mass transit based on tram traffic rarely conducted in the past. The limitations of this research were manual data collection, and the assumption that timetable frequency has significant influence on travel time, resulting in analysing travel time for short segments. Therefore, future research should predict travel time on longer segments. Additional limitation of the research is the assumption of ideal travel time based on observations. Therefore, driver behaviour, and vehicle characteristics may be considered to improve the accuracy of the model. Since the data collection could not provide stop time data, future research should include stop time data, for modelling riding time and stop time separately
Development of an Instrument Procedure Flying Training Device
No full textSvrha izrade trenažera za uvježbavanje postupaka instrumentalnog letenja je upoznavanje korisnika s radom radionavigacijskih sredstava i zrakoplovnih navigacijskih instrumenata. Uporabom ovog trenažera se omogućava stvaranje mentalne slike pozicije zrakoplova u odnosu na radionavigacijska sredstva te savladavanje i automatizacija postupaka za letenje po tim sredstvima.The purpose of developing an instrument procedure flying training device is to acquaint users with the operation of radionavigation aids and aircraft navigation instruments. The use of this training device enables users to create a mental image of the aircraft's position in relation to radio navigation aids and to master and automate procedures for flying by these aids
Monitoring of Scheduled and Unscheduled Maintance by Flight Hours of Zlin 242-L Airplane
No full textGlavni cilj održavanja vojnih zrakoplova je što veća operativna raspoloživost zrakoplova za obavljanje zadaća. U ovom završnom radu analiziraju podaci o planiranom i neplaniranom održavanju zrakoplova Zlin 242 L iz flote koju koristi Hrvatsko ratno zrakoplovstvo. Analizirani period je osamnaest mjeseci. Prema navedenim podacima napravljen je izračun srednjeg vremena kojeg je zrakoplov proveo u radu između dva održavanja i izračun srednjeg vremena koje je zrakoplov proveo na zemlji zbog planiranog ili neplaniranog održavanja. Analizom praćenja planiranog i neplaniranog održavanja dobiva se uvid u raspoloživost zrakoplova.The main goal of maintaining military aircraft is to maximize the operational capability of aircraft to perform tasks. So, in this thesis are analyzed data of scheduled and unscheduled maintenance of Zlin 242 L airplane from the fleet used by Croatian Air Force. The analyzed period is eighteen months. According to the above data, a calculation was made of the mean time between failure which the airplane spent in operation and a calculation of mean time to repair which the airplane spent on the ground due to scheduled or unscheduled maintenance. The analysis of monitoring planned an unplanned maintenance provides insight into availability of aircraft
Application of Inventory Management Methods
No full textZalihe su jedna od najvažnijih komponenti svakog poduzeća. Omogućuju konstantnu i točnu proizvodnju i zato se svakodnevno radi na unapređenju metoda koje služe za upravljanje zalihama. Nikada se sa sigurnom točnosti ne može reći koja metoda je najbolja za svako poduzeće, ali se uz konstantno unapređenje i analize mogu napraviti kvalitetni radovi koji će poduzećima omogućiti da uz što brži i bezbolniji način adaptiraju metodu koja bi njihovom poduzeću najviše odgovarala. Cilj ovog rada je analizirati metode koje se koriste u upravljanju zalihama te njihovu primjenu. Optimizacija upravljanja zalihama provesti će se nad podacima od Jamnice plus d.o.o.Inventories are one of the most important components of any business. They enable constant and accurate production and that is why people are working every day to improve methods used for inventory management. It is never possible to say with complete certainty which method is best for each company, but with constant impovements and analysis, quality reserch can be done so companies can adapt method that would help them most in fastest and most painless way. The aim of this work is to analyze the methods used in inventory managment and their use. Inventory management optimization will be conducted over the data from Jamnica plus d.o.o
Method for Determining the Distances of Flying Objects during Aircraft Interception
No full textPresretanje je jedna od iznimno važnih zadaća koju obavljaju vojni piloti. Provedba te zadaće osigurava kontrolu i sigurnost zračnog prostora, a time i prevlast u zračnom prostoru. Za kvalitetu i brzinu presretanja važno je da su piloti upoznati s načinima određivanja udaljenosti objekta koji se presreće te sa mogućnostima zrakoplova na kojem lete. Za uspješno obavljanje te zadaće ključnu ulogu čine radari, iskustvo kontrolora za navođenje kao i sam proces od otkrivanja mete te samog pretjecanja. Tema ovog diplomskog rada je postavljanje jednadžbi i izračunavanje udaljenosti objekata u zraku, u ovisnosti o različitim podacima koje pilot može imati. Sve korištene jednadžbe su eksperimentalno ispitane i provjerena im je točnost uz pomoć korištenja GPS uređaja, mjereći podatke prilikom presretanja i kod lovca i kod mete. Dodatna proračunata stavka je i optimalna brzina prilaska lovca. Zaključak je da proračun udaljenosti ovisi ponajviše o udaljenosti mete i lovca, a što je veća udaljenost time je i pogreška podatka, kojeg kontrolor daje pilotu, potencijalno veća.Intercepting is a very important function done by military pilots. The implementation of this task assures control and safety of certain airspace and with that the land below it. Quality and swiftness of the intercepting process is assured with pilots being very well informed with methods of determining distance of the intercepting aircraft and with the limitations of their own. Alongside that radars, the experience of the military flight controller in charge and the process itself that includes everything from detecting threat to intercepting it play a huge role in the intercepting. This paper is made so the proper equations for determining distance of flying objects are made in correlation with the different information pilot can acquire during flight. All equations are experimentally assayed, and their accuracy confirmed while analyzing data harvested from the GPS devices that were installed both in the fighter and the target. An extra data that has been calculated was the optimal fighter approach speed. Conclusion is that the calculation of the distance depends mostly on the distance between fighter and target, with that said, greater the distance, greater the inaccuracy of the data given by controller could be