Article history: Received: 11.05.2020 Accepted: 27.07.2020 Published: 25.12.2020 Electrical railway systems (ERSs) are one of the largest end-users in the utility grid. Providing optimal energy management and improving efficiency in such a high-power network is a vital approach to conserve energy and decrease economic costs. Meanwhile, proper exploitation of regenerative braking energy (RBE) as a dormant potential in ERSs, is a distinguished opportunity to achieve these goals. This paper presents a proposal to achieve the mutual advantages of RBE harvesting and energy storage systems (ESSs). In the proposed strategy, a multifunctional railway power conditioner (MF-RPC) together with its smart control system is employed to realize the optimal mode of the active and reactive powers exchange in output ports. Depending on the motoring and generating powers of trains on both sides of traction substation (TSS), the proposed MF-RPC can simultaneously restore back RBE to the grid, save energy in ESSs and power other adjacent consuming trains. Regarding the intrinsic features of MF-RPC, all proposed scenarios are consistent with power quality standards. The simulation results based on MATLAB/SIMULINK are provided to confirm the effectiveness of the proposed method.
In modern societies, where sustainability, health and comfort are top of priorities, it is critical to devise new strategies to overcome this problem effectively. In line with the expansion of technology, the number of transportation increases, traffic is intense worldwide, and rail traffic is growing all over the world. Therefore, special attention is paid to railway vehicles, infrastructure maintenance and traffic safety. In the case of the interaction between a rolling wheel and a rail, forces arise from physical conditions, metal stress, deformation, noise, etc. In this context, the development of a low-cost trackside monitoring system to reduce maintenance costs and to improve ride quality is necessary. In addition, significant damages that may cause service interruptions or derailments can be prevented by early detection of wheels. In this paper, an application of a wayside monitoring system installed in the Portuguese Northern Railway Line to detect weigh-in-motion (WIM) is presented. The presented WIM system is part of a larger project PEDDIR: the Portuguese acronym for "Weighing in motion and wheel defect detection system." From the load measurement imposed by the axle onto the track, integrated into a proper algorithm, train specification can be calculated.
During the supply process of rolling stocks for metro systems, the propulsion system of trains in terms of separate power and control scheme, should be selected based on the Reliability, availability, maintainability and safety (RAMS) parameters along with some expected indexes in operation plan. This means that, in addition to undeniable control and operation advantages of a train that are equipped with the bogie based propulsion system, the performance of the train is very important when an inverter module or each propulsion systemchr('39')s component fails, and therefore it should be considered to choose the propulsion system type. Now, a technical grading of propulsion system types can be made from the point of origin which is car based type with the minimum advantages of operation, to the point of destination which is bogie based type with the maximum advantages of operation. Therefore, the semi-bogie based type that has been applied in Tehran metro trains with one common DC link, input protection circuit and control, is located in the middle of this grading. However, the definitions of the above mentioned propulsion system types are presented at the beginning of this paper, in order to clarify the functional behavior of semi-bogie based type in degraded and faulty mode of operation to determine its exact position in above mentioned grading between the first two types, some investigation will be done based on the simulation in MATLAB and the results will be presented.
In order to reach a desired quality in railway tracks and to maintain this quality in an acceptable level, a systematic and regular maintenance plan must be performed. By proper management of track maintenance and codification of proper methods to evaluate the quality of railway tracks, a desired quality can be reached. For this purpose, some indices should be defined and maintenance limits of railway tracks should be determined based on these indices. Various geometrical indices have been defined in the railways and these indices are utilized by maintenance management systems. Each of these indices, because of their limitations or some special conditions, is not dependable in some tracks and their results are not acceptable. So, the main aim of this research is to develop a dependable geometrical index and the PSD[1] method is used to achieve this goal. This paper has been tried to utilize a recently developed index compared with other indices and the relationship between this index and other indices is expressed. That is, by developing the PSD index, the relationship between PSD and TGI, PSD and CTR geometrical indices has been expressed. It was found that either of mentioned indices (TGI and CTR) has a linear relationship with PSD index. By comparing the indices it is concluded that PSD index provides more details about the geometrical status of the track. Thus, using PSD index, track maintenance decision makers will be able to schedule the maintenance programs effectively.
In this paper, for the first time a general type-2 fuzzy system (Linguistic or Mamdani) is used to estimate the sliding surface of the sliding mode control (SMC) method for train speed and levitation control. One of the important issues in controlling the train is its speed control, taking into account the cost function and control signals. Because the train system in this article is nonlinear and contains uncertain terms, a nonlinear method should be used, so type-2 fuzzy systems perform well in this regard. Also, the controller is designed to withstand external disturbances and non-modeling dynamics. In addition to system stability, the vibration signal control also improves. A comparison between general type-2 fuzzy SMC and type-1 fuzzy SMC has been done in the simulation. The simulation results prove the efficiency and superiority of the proposed method.
Article history: Received: 8.06.2020 Accepted: 14.08.2020 Published: 25.12.2020 In this paper, an innovative method as a coupled numerical model is developed for assessing the interaction between wagon dynamics and transient fluid slosh. This model can be considered as a robust and effective computational tool for investigation of sloshing in tank vehicles in different tank conditions and maneuvers. Fourth-order Runge-Kutta method is adopted for solving the 19 degrees of freedom (DOFs) wagon dynamics model. The three-dimensional model is adopted, which includes car body, bogies and wheel-axles with longitudinal, vertical, pitch, and roll vibrations. Transient fluid slosh is analyzed using the computational fluid dynamics method (CFD) based on the Navier–Stokes equations combined with the volume of fluid technique (VOF). Also, the sloshing test setup is developed for validation of the multi-phase CFD simulation. By coupling of the wagon dynamics model with the fluid slosh model, the dynamic response characteristics of the railway tanker are analyzed under straight-line braking maneuvers. The numerical parametric study is conducted to investigate the effect of filling volume and viscosity.
One of the main characteristics of the ballasted track compared to the slab track is the ability to reduce the level of vibration on the bridge surface. However, due to factors such as the asymmetric or permanent settlement of the ballast layer (compaction), crushing, or moving of ballast particles, a gap between sleeper and ballast appears. This problem intensifies vibrations in the track and, as a result, can affect the dynamic response of the bridge. So far, the lack of scientific attention to this issue on the railway bridge is noticeable. Hence, in this article, by examining a nonlinear dynamic model of Train-Track-Bridge interaction, the effect of the unsupported sleeper on the dynamic behavior of a concrete railway bridge is studied. For this purpose, the influence of a suspended sleeper-group at the different positions along the bridge span, in a range of train speed and gap size, are investigated. It is demonstrated that for the case of the unsupported sleeper-group within the 2/8 and 5/8 of the bridge span, the acceleration of the bridge reaches its maximum. Also, the maximum load on the deck of the bridge increases by 45 to 60%.
The industry has been faced with the difficulty of Safety level determination of safety systems. Some standards including ISAS 84.01 and IEC61508 have provided some guidelines but there is no a complete and comprehensive understanding about these standards and their accomplishment. It should be noted that the security analysis is one of the most important factors to measure the risk level, as its measurement in certain environment is difficult, so in this study a new approach is proposed to analyze the risk level of safety instruments in fuzzy environment. The new methodology is applied on a train barking system as a case study and the results indicated that the level of safety integrity level is influenced by the security factors. The determination of safety integrity level needs to implement the safety functions and the uncertainty of probabilistic model parameters, which are affected by the results of security analysis. The level of safety integrity in fuzzy environment is calculated by proposing fuzzy fault tree analysis and the results have been compared with the concluded results obtained from certain methods.
Today the most significant issue in Mega cities is Public Transport. Citizens need to be satisfied by public Transport systems to use them more frequently than their own private vehicles. In order to make progress in public Transport Systems such as Buses and Light rail, the users’ satisfaction is vitally important. There are advantages and disadvantages in every transport system, what matters more is that positive ones outcome negative ones. Hence, Systematic approach to select one of them is crucial for cities like Tehran. In this paper, it is tried to investigate the users’ preference by comparing different effective indices like Benefit to Cost analysis, Passengers satisfaction, Traffic Congestion, Environmental emissions, operational costs, and time wasting in order to have BRT and light rail, particularly Monorail and Tramway prioritized. Consequently, they are compared and analyzed with TOPSIS method on SPSS. In order to have an accurate comparison each index is investigated through a question in a questionnaire. They are carefully responded by thirty experienced public transport expert. The results showed that questionnaire has high validity. Based on the experts’ judgement, Monorail is prior to Tramway, while Tramway is prior to BRT itself.
Switches are the vital elements of the rail network, and due to the discontinuity of the rail in these sections, the cost of repair and maintenance as well as the risk of an outbound event is greater than the other sections of the railroads. In this study by analyzing the data extracted from the instrumented crossing under combined traffic, after the initial processing of the signals, the characteristics of different trains were identified from the recorded data. The acceleration parameter of the switch crossing nose under train wheel passages was recorded as a measure of the intensity of the trainschr('39') impact on the crossing panel with an accelerometer mounted on the rail at the crossing nose. The results of field measurements for different trains with different speeds were compared and the feasibility of increasing speed of trains from the straight line of the switch was done assuming safe passage in the present situation of track. Based on the results of field tests, train sets up to speed 160 and passenger trains up to 115 km/h can be accelerated. Freight trains are not allowed to increase speed to maintain current situation of crossing response.
Rail system is considered as the most efficient mode of freight transportation. While it may be expected that demand of rail mode would be higher than other means of transportation, sometimes it has been observed that road transportation is much more applicable. Therefore, economic aspects of transportation market such as process and access charges are prominent. It must be considered that rail transportation has its own drawbacks. Low flexibility and fixed origins and destinations, as well as the relatively high rate of access charges are regarded as the most problematic limitations of rail systems. In current study, an evaluation is carried out using game theoretic approaches in order to determine demands of two competing systems including rail and road. Moreover, Stackelberg approach is utilized in order to calculate optimal access charge of rail infrastructure which maximizes profit of government. The results and findings of current study may contribute policy makers for decision-making in a competitive freight transportation market.
In this paper, the driving force calculation of a cracked railway wheel is studied, and the effects of thermal loads due to braking, train speed, and elastic-plastic material model are considered. Since the wheels are subject to fatigue loading and the property of its material is elastic-plastic, the study of crack growth in them is necessary because, in the case of existing a crack in the wheel and reaching its critical lengths, the failure of the wheel will occur. This is one of the important reasons for the accidents and derailment of trains. In this paper, the investigation of crack growth in the wheel is performed by two primary methods, linear elastic fracture mechanics (LEFM) and elastic-plastic fracture mechanics (EPFM) each of them has their specific condition of use. The applicability of each method in different conditions is discussed. The results demonstrate the importance of thermal loads of braking, train speed, and cyclic hardening material behavior on the usage of different approaches to achieve the appropriate crack driving force.
In railway stations, an appropriate facility planning and layout design leads to enhance efficiency and passenger satisfaction. The present study provided a methodology to design facility layout by integrating simulation and optimization for passengers in public location, as well as proposing an innovative model to allocate candidate location to the facility. The proposed model results in the selection of the location for the facility with any dimension and without space limitation. Furthermore, it is usable for passenger’s terminal and all public locations. The advantages of the proposed model are reducing some parameters such as the movement duration of passengers, experienced passenger density, and flow rate, and increasing the quality of passenger terminals.
In this paper, a hybrid experimental/numerical methodology for the assessment of railway induced ground-borne noise and vibration in buildings based on experimental measurement in the ground surface is proposed and validated using synthetic data. The application of such approach is focused in the prediction of vibrations and re-radiated noise inside buildings to be constructed nearby existing railway infrastructures. After the presentation of the concept, the numerical validation of the proposed approach is shown for a 2D example. The proposed method can be easily generalized for 3D conditions.
In this study, a new approach for the evaluation of horizontal curve design in railway tracks integrating safety criteria is proposed. To conduct this research, a vehicle-track interaction model is developed in ADAMS Rail program and simulation of dynamic vehicle response from derailment point of view is followed. Using this model, sensitivity analyses are made on the main geometry parameters of horizontal curves, including radius, super-elevation and transition length, considering different speeds. Consequently, the influences of each parameter are investigated on governing derailment criteria i.e. overturning, Nadal and Prud’homme. The obtained results form the basis for further practical charts by which, both the geometry design and safety evaluation of railway horizontal curves can be determined. A practical use of the new approach is finally presented to indicate its capability and applicability.
This paper which is intended to review UAV-based railroad facility maintenance technologies includes the analysis of the tendency on how to utilize growing UAV technologies for railroad facility maintenance. In the United States and European countries, task forces dedicated to railroad facility maintenance using UAV have been established to conduct the facility diagnosis and safety & security process through competent operator, analyzer and developer and UAV has been used more commonly for catenary, supports, station structure and railroad bridge. The factor to be considered before applying UAV to the inspection of railroad facility is drafty conditions and particularly, UAV used in railroad sector is small in size which is vulnerable to environmental factors. To deal with such shortcomings, the study on disturbance resistance algorithm by modeling the attitude control and drafty environment and controller design to enhance hovering accuracy have been actively underway currently. However, in a bid to be able to apply UAV to railroad facility management, it is necessary to solve such problems as sensor error and abnormal GPS signal first.
The electric transportation systems as huge demands of main electric network, play major role in transferring passengers and goods throughout the world. Since the peak power consumption of mentioned systems, have time overlap with the peak power demand of main electric network, the supplying procedure of them has negative impacts on their upstream grid. One of the best solutions to alleviate the negative impacts is the utilization of regenerated energy of braking trains as a distributed generation in electric transportation system as well as the solar energy sources in other power systems. The distributed generations will penetrate into the supply chains more effectively if benefit from energy storage systems. The scope of this study is shaving the peak power consumption of electric transportation system by proposing an integrated electric transportation system containing electric railway system, fast charging station for electric vehicles, energy storages and distributed generations. A smart energy management system defines power flow strategies so that the shifting power demand from grid point of view could be proceeded. To clarify the issue, the smart configuration is compared with the traditional system. Thus, the proposed configuration is simulated in HOMER software and results are analyzed.
The hardware in the loop simulation has many uses in design, calibration, and performance validation of initial prototypes made from controllers. Using this feature, the reliability and time of commercialization required by the system with an effective cost method can be maintained. Considering the importance and cost of object controller system in the rail transport, the use of hardware in the loop in the development of these controllers at all stages of design and implementation can be a significant useful aid. In this paper, a hardware in the loop test-table has been designed, which it has been used for testing the performance of the objective controller's Lamp board, known as controller and communication display board. In this regard, the simulator's performance evaluated after assurance of its proper functioning by an accuracy test. The design table consists of a host computer, RS232 data transmission, and the Arduino board. The results show that the designed test table can be used to evaluate the accuracy or inaccuracy of all the algorithms used without need cost of testing on the actual system due to a real-time communication. The length of the development of the board reduced greatly by this method.
Finding the optimal location of new stations along the rail transportation network is considered in this study by proposing a mathematical model. Two simultaneous effects on railway demand points (users) are investigated, namely, the time effect and the covered population which is achieved by constructing new stations. The better accessibility of demand points to rail network is considered as the positive one and the negative effect concerns the increased travel time induced by additional stops at newly constructed stations. Two objective functions are considered including the saved travel time and the covered population. The proposed model has been implemented as a case study on Tehran subway network and the results are presented.
Using bidirectional converters in Metro substations, regenerative braking energy can be fed back to the AC grid to decrease the braking energy loss. In this paper, effectiveness of bidirectional rectifiers and their placement are investigated. A case study is provided for determination of optimal location and capacity of bidirectional rectifiers in 8 rectifier substations for different traffic scenarios in portion of line 1 of the Tehran Metro system. particle swarm optimization (PSO) method is used for selection of optimal traction substation for inverter placement, Finally, the results of simulation and optimization using the software built in MATLAB / SYMULINK is presented. Simulation results confirm the effectiveness of using bidirectional rectifiers as well as the optimization method.
