Articles
Vol. 25 No. 5 (2013)
Published on 27.10.2013
Davor Sumpor
2013 (Vol 25), Issue 5
Sandra Kasalica, Dragomir Mandić, Vojislav Vukadinović
2013 (Vol 25), Issue 5
Intention– Cyclic locomotive assignment planning is a specific type of organization of locomotive usage, and in fact, it means putting the complete workload to a closed chain, which is repeated periodically. The concept of cyclic locomotive assignment planning type organization in the area of train traction has proven in practice as the best one, but as it is made for in-advance defined timetable and without considering the stochastic nature of the timetable realization process, it leads to incompatibility in using locomotives. Methodology – Methodology defined in this paper contains: research of train delays on the Serbian Railways and Montenegrin Railways networks, analysis of the real system organization of locomotive usage in conditions of train delays, theoretical thesis of solving the problem of optimal cyclic locomotive assignment planning in conditions of train delays, designing of a model with algorithms, preparing the software package, testing the model and program with results, as well as the conclusions drawn from the complete research project. Results– The optimization model of cyclic locomotive assignment planning during the process of making timetable including train delays has been defined. Conclusion –The obtained results have shown as expected, that the larger delays of trains required a larger number of locomotives. However, by using this model it is possible to optimize the required number of locomotives, taking into account the real time delays of trains.
Jelena Budak
2013 (Vol 25), Issue 5
Ali Ghasemi
2013 (Vol 25), Issue 5
The problem of controlling a string of vehicles moving in one dimension is considered so that they all follow a lead vehicle with a constant spacing between successive vehicles. This paper is concerned by considering both effect of the parasitic time delays and lags and comfort specification. The Contribution of this paper is two-fold. Firstly, most physical systems often involve parasitic time delays and lags. Due to practical design and implementation, the negative effect of the parasitic time delays and lags on the string stability be taken into account Secondly, the aim here, however, is specifically to consider the restrictions which need to be imposed on the control parameters, in order to be well-suited with bounds on the dynamic variables as well as the requirement for string stability. At the end the robustness against the noise in the measurement signals factors are studied.
Senka Sekularac-Ivošević, Sanja Bauk, Mirjana Gligorijević
2013 (Vol 25), Issue 5
This paper considers the effects of combination of two different approaches in developing seaports positioning strategy. The first one is based on comparing the most important quantitative and qualitative seaports choice criteria by benchmarking method. Benchmarking has been used in creating the appropriate model for efficient marketing positioning of Aegean, Adriatic and Black Sea seaports. The criteria that describe the degree of these seaports competitiveness are chosen upon the investigation of ports customers’ preferences. The second employed approach based on matrix game concept has been used for the purpose of optimal repositioning of the ports. Though, nine selected ports’ functions are treated in a way that they are divided into two sets: one composed of the functions which are to be developed, and the other consisted of the functions for which it is expected to be suppressed in the future. According to the numerically obtained results the ports are repositioned, and corresponding explanations are given in the marketing manner. The mixture of these two concepts should contribute to the review of the state of these business systems and their images at the market, as well as to open prospective toward finding out the ways of creating and maintaining their competitive advantages.
Fang Zong, Jia Hongfei, Pan Xiang, Wu Yang
2013 (Vol 25), Issue 5
This paper presents a model system to predict the time allocation in commuters’ daily activity-travel pattern. The departure time and the arrival time are estimated with Ordered Probit model and Support Vector Regression is introduced for travel time and activity duration prediction. Applied in a real-world time allocation prediction experiment, the model system shows a satisfactory level of prediction accuracy. This study provides useful insights into commuters’ activity-travel time allocation decision by identifying the important influences, and the results are readily applied to a wide range of transportation practice, such as travel information system, by providing reliable forecast for variations in travel demand over time. By introducing the Support Vector Regression, it also makes a methodological contribution in enhancing prediction accuracy of travel time and activity duration prediction.
Đani Mohović, Robert Mohović, Igor Rudan
2013 (Vol 25), Issue 5
Ship grounding is one of the primary maritime navigation casualties and a result of an error made by the navigating officer, of a technical failure on vital ship equipment or of force majeure. In order to decrease the risk of grounding in such cases, this paper explores the ship movement during navigation when an extraordinary event occurs, such as steering system failure that affects the vessel’s direction directly and speed indirectly. One way to determine the ship movement in such circumstances is by simulating the ship movement on the navigational simulator according to the predefined scenarios, as explained in this paper. A total of 60 scenarios were researched, in the process of which ship type, ship size, ship speed and rudder deflection angle were varied. During the simulation, all relevant data concerning current movement of the ship and a graphical display of the performed simulation were recorded every 30 seconds. On the basis of the simulation results it is possible to determine the worst case scenario which can be used to define the consequence of grounding, one of the parameters necessary for the assessment of the risk of grounding.
Mian Yang, Y.J. Wang
2013 (Vol 25), Issue 5
A major problem addressed in railway network planning relates to distinguishing the role of the railway line in the network, and making a reasonable classification of the lines based on their role. Accessibility has been widely used to measure the role of transportation infrastructure in various studies, but few quantitative models for the classification of the role have been presented yet. In this paper, the line accessibility classification model is proposed, which aims to distinguish the role of railway lines in the network and to classify the lines into different grades. The practicability of the model is demonstrated through the case study of Northeast China railway network where the railway lines in Northeast China can be classified into three grades. The line accessibility classification model is supposed to be a strategic decision support tool for planners and policy makers to determine the classification of railway lines.
Tomaž Tollazzi, Goran Jovanović, Marko Renčelj
2013 (Vol 25), Issue 5
The problems of low level traffic safety on multi-lane roundabouts have been resolved in various ways in different countries, usually by using alternative types of roundabouts that reduce the number of conflict points. Alternative types of roundabouts typically differ from 'normal' or 'standard' roundabouts in one or more design elements, as their implementation purposes could also be specific. Today, several different types of roundabouts are already in use ('mini', 'double mini', 'dumb-bell', those 'with joint splitter islands' ('dog-bone'), those 'with a spiralling circular carriageway' ('turbo'), those 'with depressed lanes for right-hand turners' ('flower') etc.). This paper introduces a new type of roundabout, dual one-lane roundabouts on two levels with right-hand turning bypasses, namely the 'target roundabout'. This paper describes and analyses their design, traffic safety, and capacity characteristics, compared with the standard two–lane roundabouts.
Luoyi HUANG, Jiao YAO, Wei WU, Xiaoguang YANG
2013 (Vol 25), Issue 5
With the evolution of advanced wireless communication technologies, tremendous efforts have been invested in vehicular networking, particularly the construction of a vehicle-to-vehicle communication system that supports high speed and mobility. In vehicle-to-vehicle communication environment, vehicles constantly exchange information using wireless technology.
This paper aims to propose a vehicle-to-vehicle communication system and validate the feasibility of the system on a suburban road in China. Two vehicles were used equipped with IEEE 802.11p based DSRC (Dedicated Short Range Communications) device to construct a vehicle-to-vehicle communication platform. The system architecture consisting of hardware and software was described in details. Then, communication characteristics such as RSSI (Received Signal Strength Indicator), latency and PLR (packet loss rate) were analyzed. Additionally, GPS-related information (such as ground speed and location) was obtained through field test on a suburban road in Shanghai and Taicang City. The test results demonstrate satisfactory performance of the proposed system.
Ioan Felea, Istvan Csuzi, Eva Barla
2013 (Vol 25), Issue 5
Energy conservation is one of the key priorities of sustainable development strategy. Transport systems are responsible for about one third of energy consumption. As result, the identification of solutions to reduce energy consumption in these systems is essential for the implementation of the sustainable development strategies. The present work is dedicated to identifying the possibilities for a reduction in the consumption of electric energy in electric urban public transport systems, using the audit of their electricity system. After justifying the importance of these concerns, a mathematical model of the electrical energy balance of the electric urban public transport system and its components is presented. The analysis is applied to determine the losses in the system components and useful energy, based on the evaluation and energy consumption measurements. The measurements to reduce energy losses are identified and characterized under technical and economic aspect, optimal electrical energy balances being done on this basis.
