International Journal of Railway Research
http://www.ijrare.iust.ac.ir
International Journal of Railway Research - Journal articles for year 2016, Volume 3, Number 1Yektaweb Collection - http://www.yektaweb.comen2016/12/11Deflection measurement of masonry arch bridges with tall piers: case study of Shahbazan bridge
http://ijrare.iust.ac.ir/browse.php?a_id=70&sid=1&slc_lang=en
A common practice for detailed assessment of masonry bridges is to use recorded deflection signature of mid-span of such structures due to predefined loading schemes. However, measuring the deflection of bridges with tall piers or those situated over deep valleys introduces certain difficulties, since common deflection-meters require a reference point relative to which the measurement is carried out. Common approaches currently proposed by researchers include indirect measurement of deflection based on acceleration or tilt measurements; but due to small values of deflection in masonry arch bridges, such approaches may not produce the expected results. Moreover, optical methods are difficult and rather expensive to implement due to small deflection values and far reaching points. This paper proposes the application of piers as the reference point of common deflection meters. To demonstrate the applicability of the proposed approach, a case study is carried out in which a 70 years old railway masonry arch bridge is instrumented for structural health monitoring. The studied bridge is a seven span railway masonry arch bridge with tall piers of almost 40 meters and span lengths of 21.5m. It is concluded that vertical deflection signature of conventional method could be derived from inflating that of proposed method by a factor of 1.86. Therefore, the method proves to be practical for the purpose of structural health monitoring and calibration of numerical models.Shervan AtaeiTwo Comprehensive Strategies, to Prioritize the Capacity Improvement Solutions in Railway Networks (Case Study: Iran).
http://ijrare.iust.ac.ir/browse.php?a_id=73&sid=1&slc_lang=en
The aim of this study is to present two comprehensive strategies for prioritizing the capacity improvement solutions in the railway networks. The solutions considered in this study include: promoting to double-track railways, block signaling system, electrification and re-opening the closed stations. The first strategy is based on a local approach, which concentrates on the critical block sections individually; whereas the second one is based on a global approach, for which the solutions are executed according to the load flow of the network and the capability of the demand absorption after removing the bottlenecks emerged in the specific corridors. For both strategies, the value of the absorbed excessive demand, the benefits, the costs, and the net present value (NPV) indicator are employed to compare the solutions. To evaluate the proposed strategies, Iranian railway network was examined. The results demonstrate the excellence of the second strategy, rather than the first one. By executing the first and the second strategies, 45.6 and 52.52 million tons per year, of the total potential demand can be absorbed to the network, respectively. The NPV values were 5.78 and 7.81 billion dollars for first and second strategies, respectively. In spite of more investments required, the second strategy is more efficient, rather than the first one.Mohammad TamannaeiAn Efficient Strategy for Power Rating Reduction of Back-to-Back Converters Used in Railway Power Conditioner
http://ijrare.iust.ac.ir/browse.php?a_id=45&sid=1&slc_lang=en
<p>One of the most common solutions to deal with the power quality issues of electrical railway systems is employing Railway Power Conditioner (RPC). In the conventional mode of operation, the RPC power rating deployed in every Traction Power Substation (TPS) is significantly large. This paper mainly focuses on the power rating reduction of RPC through presenting of a novel combinatorial compensation method. The inductive and capacitive switching algorithm retrieved from Steinmetz circuit lead to additional auxiliary balance in sequential TPS which declines the RPC function in elimination of the Negative Sequence Current (NSC). The proposed method can reduce the voltage over Sectioning Posts (SP), DC-link operation voltage, back-to-back (B2B) converters rating and installation costs. The accuracy and effectiveness of the proposed strategy are confirmed via simulation results obtained by MATLAB/SIMULINK program.</p>
Saeed FazelVolume-Filling Effects on Sloshing Frequency in Simplified and Explicit Dynamic Finite Element Models of Tank Wagons during Braking and Turning
http://ijrare.iust.ac.ir/browse.php?a_id=44&sid=1&slc_lang=en
<p>Numerical analysis of fluid sloshing in tank wagons is one of the updated matters focused by railway engineers. The free surface of fluid becomes unstable and turns into a dynamic complex non-linear problem for fluid-structure interaction (FSI). In this paper, first, the dynamic response of the tank, including lateral force analysis and pressure distribution during braking, is obtained using an explicit dynamic finite element model based on the Multi Material Arbitrary Lagrangian Eulerian method (MM-ALE); then, the simplified model is developed for sloshing during turning. Numerical finite element model is validated using a test setup data. Comparing these models during turning with parametric studies for tank filling, it is observed that frequency and sloshing amplitude, when filling is less than 25%, have less than 10% of difference; therefore, the simplified model in the above conditions can be used with an acceptable accuracy because of a remarkable reduction in the time and cost of numerical calculations.</p>
Majid SharaviKnowledge based system for the evaluation of safety and the prevention of railway accidents
http://ijrare.iust.ac.ir/browse.php?a_id=43&sid=1&slc_lang=en
<p>This paper describes our contribution to improving the usual safety analysis methods used in the certification of railway transport systems. The methodology is based on the complementary and simultaneous use of knowledge acquisition and machine learning. The purpose is contributed to the generation of new accident scenarios that could help experts to conclude on the safe character of a new rail transport system. The method of analysis and evaluation is centered on the summarized failures (SFs) which are involved in accident scenarios capitalized. A summarized failure (SF) is a generic failure produced by the combination of a set of basic failures which has the same effect on the performance of the system. Each scenario brings into play one or more SFs.</p>
<p>The purpose is to automatically generate a recognition function for each SF associated with a scenario class. The SF recognition function is a production rule which establishes a link between a set of facts (parameters which describe a scenario or descriptors) and the SF fact. A base of evaluation rules can be generated for each class of scenarios. The SF deduction stage requires a preliminary phase during which the rules which have been generated are transferred to an expert system in order to construct a scenario evaluation knowledge base. The evaluation knowledge base is exploited by forward chaining by an inference engine and generates the summarized failures (SFs) which must enter into the description of the scenario which is to be evaluated. </p>
Habib HADJ MABROUKCrashworthiness analysis and energy absorption enhancement of a passenger rail vehicle
http://ijrare.iust.ac.ir/browse.php?a_id=65&sid=1&slc_lang=en
<p>Interests of increasing the speed of high speed trains, brought more wryness about probable accidents. Whereas passenger wagon carbody is considered as a safe compartment for passengers, therefore, great attention should be paid on its design. In this study, a passenger carbody (made by Eastern Germany) and its chassis are modeled to simulate crash analysis according to EN 15227 standard. Then, obtained results are used in order to optimize the wagon chassis. This investigation is performed in two steps. In the first step, which consists of simulation of the original wagon model, it is found that due to the lack of efficiency in crash force absorbent, some modifications are needed to consider. In the second step, the original chassis is modified according to modern ones and by implementing honeycomb cores as energy absorbing device, higher absorbed energy is yielded. Also, impact stresses in mid-section of the chassis considerably decreased. The proposed energy absorbing device can be implemented in front end of the chassis to provide a crashworthy structure, however, other investigations such as modal analysis and strength determination should be conducted precede the final structure.</p>
Habibollah Molatefi