Using neural networks in the process of calibrating the microsimulation models in the analysis and design of roundabouts in urban areasIrena Ištoka Otković
, 2011, doktorska disertacija
Opis: The thesis researches the application of neural networks in computer program calibration of traffic micro-simulation models. The calibration process is designed on the basis of the VISSIM micro-simulation model of local urban roundabouts.
From the five analyzed methods of computer program calibration, Methods I, II and V were selected for a more detailed research. The three chosen calibration methods varied the number of outgoing traffic indicators predicted by neural networks and a number of neural networks in the computer program calibration procedure. Within the calibration program, the task of neural networks was to predict the output of VISSIM simulations for selected functional traffic parameters - traveling time between the measurement points and queue parameters (maximum queue and number of stopping at the roundabout entrance). The Databases for neural network training consisted of 1379 combinations of input parameters whereas the number of output indicators of VISSIM simulations was varied. The neural networks (176 of them) were trained and compared for the calibration process according to training and generalization criteria. The best neural network for each calibration method was chosen by using the two-phase validation of neural networks.
The Method I is the calibration method based on calibration of a traffic indicator -traveling time and it enables validation related to the second observed indicator – queue parameters. Methods II and V connect the previously described calibration and validation procedures in one calibration process which calibrates input parameters according to two traffic indicators.
Validation of the analyzed calibration methods was performed on three new sets of measured data - two sets at the same roundabout and one set on another location. The best results in validation of computer program calibration were achieved by the Method I which is the recommended method for computer program calibration.
The modeling results of selected traffic parameters obtained by calibrated VISSIM traffic model were compared with: values obtained by measurements in the field, the existing analysis methods of operational roundabouts characteristics (Lausanne method, Kimber-Hollis, HCM) and modeling by the uncalibrated VISSIM model. The calibrated model shows good correspondence with measured values in real traffic conditions. The efficiency of the calibration process was confirmed by comparing the measured and modeled values of delays, of an independent traffic indicator that was not used in the process of calibration and validation of traffic micro-simulation models.
There is also an example of using the calibrated model in the impact analysis of pedestrian flows on conflicting input and output flows of vehicles in the roundabout. Different traffic scenarios were analyzed in the real and anticipated traffic conditions.
Ključne besede: traffic models, traffic micro-simulation, calibration of the VISSIM model, computer program calibration method, neural networks in the calibration process, micro-simulation of roundabouts, traffic modeling parameters, driving time, queue parameters, delay
Objavljeno: 02.06.2011; Ogledov: 3613; Prenosov: 252
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Terminal airspace capacity modelMilan Janić
, Vojin Tošić
, 1982, izvirni znanstveni članek
Opis: The objective of the research described in this paper was to produce a model for the analysis of terminal airspace capacity and the sensitivity of this capacity to the parameters which influence it. The model developed is based onthe concept of an expected ultimate capacity and applies to arriving traffic under saturation conditions i.e. a constant demand for service. It is possible to use the model for planning and operational purposes: for the computation of terminal airspace capacity, the separation of aircraft at the terminal entry gates so as to provide maximum capacity, and for heuristic optimization of arriving aircraft trajectories through the terminal airspace. For a sensitivity analysis the model allows for changes in terminal airspace geometry, runway(s) in use, arriving aircraft trajectories, arriving traffic distribution between the terminal airspace entry gates, aircraft type mix, aircraft velocities and air traffic control separation rules.
Ključne besede: air traffic, capacity model, terminal traffic
Objavljeno: 05.06.2012; Ogledov: 853; Prenosov: 51
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Traffic modelling and performance evaluation in the Kotor cruise portDavorin Kofjač
, Maja Škurić
, Branislav Dragović
, Andrej Škraba
, 2013, izvirni znanstveni članek
Opis: Simulation modelling of traffic in the Kotor cruise port is used for performance evaluation and optimization of the operational policy. During the summer, the traffic intensity of the cruise shipsŽ arrivals is higher than in other periods of the year. The increased traffic intensity causes congestion at anchorages, which can lead to significant dissatisfaction of the cruise ship operators and passengers. The simulation model, based on the port callingfrequency statistics and port tariff charges, is developed. First, the simulation model is validated against the real data. Second, several simulations are performed, where the scenarios of an extended main berth and of increased traffic intensity are evaluated in order to minimize congestion and to maximize revenue. Simulation results indicate significant queue reductions and a higher revenue, thus justifying the intention in the main berth extension.
Ključne besede: traffic modelling, port revenue, operational policy, simulation, model validation, Kotor cruise port
Objavljeno: 30.12.2015; Ogledov: 586; Prenosov: 41
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Intellectual capital - developmental resource of logistic companies for the 21st centuryRatko Zelenika
, Drago Pupovac
, 2003, pregledni znanstveni članek
Opis: On the basis of relevant scientific research this paper systematically and concisely elaborates the interaction between intellectual capital and logistic services production. Full attention is given to intellectual capital as a factor in effective creation of the logistic processes or in other words, to prove the statement that the first place for achieving competitive advantages in the global and/or regional market of logistic services belongs to knowledge used to produce or improve the existent logistic systems and to create new ones.Further, the paper deals with the tasks of creative logistic managers as open, dynamic and stochastic systems based on knowledge or the creation of universal logistic model determined by the fact that intellectual capital and technological paradigm create the way to new logistic paradigm.Special attention is paid to building and presenting a mathematical model for measuring the intellectual capital as well as the success of its use in different logistic companies.
Ključne besede: traffic, transport, logistics, developement, intellectual resources, logistic model, mathematical model
Objavljeno: 02.06.2017; Ogledov: 221; Prenosov: 38
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Estimating marginal infrastructure cost in new infrastructure charging modelMarjan Sternad
, Timotej Jagrič
, Bojan Rosi
, 2017, izvirni znanstveni članek
Opis: Competitiveness of rail transport compared to road transport has been reducing, especially on regional railway lines. To improve this situation, the EU adopted various directives and regulations to increase efficiency of railway undertakings. In this paper we present an organizational and economic model based on European policies for local railway system. The organizational model is based on multi-criteria decision analysis. For the economic model we used an econometric approach to estimate the cost function and marginal costs in regional lines, which constitute the basis for railway charges. By implementing such an organizational model, the functioning of the railway network will improve. The research found that a change in the existing model of calculating costs of infrastructure use would bring economic effects for the railway infrastructure manager and the providers of transport. Using the proposed model we also found that it is reasonable to increase the flow of goods on unused regional railway lines because the railway infrastructure maintenance costs are inelastic with regard to transported gross tons.
Ključne besede: econometrics, charging model, maintenance cost, marginal costs, railway infrastructure, railway traffic, logistics, Slovenia
Objavljeno: 09.08.2017; Ogledov: 381; Prenosov: 159
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Multiphase approach to developing model of logistics for coastal tourist destinationsSanja Bauk
, Željko Ivanović
, 2016, samostojni znanstveni sestavek ali poglavje v monografski publikaciji
Opis: The process of urbanization of coastal tourist destinations (CTDs) is taking place at high speed and at the same time creating a lot of complex problems. The positive trend of urbanization has resulted in increased volume of freight transport which leads to burdening the traffic network, time losses and causes traffic congestion problems on the streets with increased environmental pollution due to emissions, noise and vibration. These findings brought to some research being started on the EU level, aiming to develop new logistic solutions, so these areas could be developed on a sustainable basis. With this in mind, the paper proposes a method of developing a novel model of logistics (MoL) for CTDs through several stages. The point of proposed MoL lies in achieving optimal connectivity of transportation, warehousing and physical distribution of goods, and making it a single functional model, so as to allow simultaneous optimization of logistic processes in a CTD, and to incorporate logistics in tourist offer.
Ključne besede: coastal tourist destinations, urbanization, traffic network, sustainable logistic solutions, model of logistics, optimization
Objavljeno: 09.05.2018; Ogledov: 211; Prenosov: 147
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