scholarly journals Ranking the critical sections of railway networks

2020 ◽  
pp. 095440972092568
Author(s):  
Ratthaphong Meesit ◽  
John Andrews
Keyword(s):  
Network Flow ◽  
Topological Analysis ◽  
Preventive Strategy ◽  
Railway Network ◽  
Macroscopic Models ◽  
Railway Systems ◽  
Railway Networks ◽  
Network Simulation Model ◽  
The Impact ◽  
Critical Sections

Railway systems are now facing an increasing number of threats such as aging infrastructures and climate changes. The identification of critical network sections provides infrastructure managers with the ability to understand the impact of a disruption and creates a suitable preventive strategy to counter such threats. To this end, various vulnerability analysis methods have been proposed for railway networks. Two main types of methods, network topological analysis and network flow-based analysis, have been developed. Both approaches are constructed based on macroscopic models, which take only some railway properties such as network structure, train and passenger flow into account. Thus, the results obtained are high level approximations. This study proposes a new analysis method, which is developed based on the stochastic-microscopic railway network simulation model. The method can be applied to identify the critical sections of a railway network. The effect of impact levels and occurrence times of a disruption on the network section criticality is presented. An application of the proposed model is demonstrated using the Liverpool railway network in the UK.

scholarly journals Network Characteristics and Vulnerability Analysis of Chinese Railway Network under Earthquake Disasters

2020 ◽  
Vol 9 (12) ◽  
pp. 697
Author(s):  
Lingzhi Yin ◽  
Yafei Wang
Keyword(s):  
Internal Structure ◽  
Network Flow ◽  
Spatial Location ◽  
Clustering Coefficient ◽  
Node Degree ◽  
Railway Network ◽  
Network Characteristics ◽  
Operation Rules ◽  
The Impact ◽  
The Relationship

The internal structure and operation rules of railway network have become increasingly complex along with the expansion of the network, putting a higher demand on the development of the railway and the reliability and adaptability of the railway under earthquake disasters. The theory and method concerning complex railway network can well capture the internal structure of railway facilities system and the relationship between subsystems. However, most of the research focuses on the vulnerability based on the logical network of railway, deviating from the actual spatial location of railway network. Additionally, only random attacks and deliberate attacks are factored in, ignoring the impact of earthquake disasters on actual railway lines. Therefore, this paper built a geographic railway network and analyzed topological structure of the network and its vulnerability under earthquake disasters. First, the geographic network of Chinese railway was built based on the methods of complex network, linear reference and dynamic segmentation. Second, the spatial distribution of railway network flow was analyzed by node degree, betweenness and clustering coefficient. Finally, the vulnerability of the geographic railway network in areas with high seismic hazards were assessed, aiming to improve the capacity to prevent and resist earthquake disasters.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

scholarly journals A next step in disruption management: combining operations research and complexity science

2021 ◽  
Author(s):  
Mark M. Dekker ◽  
Rolf N. van Lieshout ◽  
Robin C. Ball ◽  
Paul C. Bouman ◽  
Stefan C. Dekker ◽  
...  
Keyword(s):  
Operations Research ◽  
Complexity Science ◽  
Rolling Stock ◽  
Accurate Information ◽  
Disruption Management ◽  
Railway Systems ◽  
Decentralized Decision Making ◽  
Control Situations ◽  
Management Techniques ◽  
The Impact

AbstractRailway systems occasionally get into a state of being out-of-control, meaning that barely any train is running, even though the required resources (infrastructure, rolling stock and crew) are available. Because of the large number of affected resources and the absence of detailed, timely and accurate information, currently existing disruption management techniques cannot be applied in out-of-control situations. Most of the contemporary approaches assume that there is only one single disruption with a known duration, that all information about the resources is available, and that all stakeholders in the operations act as expected. Another limitation is the lack of knowledge about why and how disruptions accumulate and whether this process can be predicted. To tackle these problems, we develop a multidisciplinary framework combining techniques from complexity science and operations research, aiming at reducing the impact of these situations and—if possible—avoiding them. The key elements of this framework are (i) the generation of early warning signals for out-of-control situations, (ii) isolating a specific region such that delay stops propagating, and (iii) the application of decentralized decision making, more suited for information-sparse out-of-control situations.

The Effect of Friction Modifiers on Wheel/Rail Isolation

2008 ◽  
Author(s):  
E. A. Gallardo Hernandez ◽  
J. Cotter ◽  
R. Lewis ◽  
D. T. Eadie
Keyword(s):  
Input Voltage ◽  
Electrical Circuit ◽  
Friction Modifiers ◽  
Friction Modifier ◽  
Contact Impedance ◽  
Static Tests ◽  
Railway Systems ◽  
Significant Difference ◽  
Track Circuit ◽  
The Impact

Train detection, for signalling purposes, is often by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit, i.e. the wheels and axle act as a shunt. Contamination on the track such as ballast dust, rust, oil, or leaves as well as substances designed to improve train operation such as friction modifiers or sand may cause the contact between the wheelsets and the track to be compromised, inhibiting train identification. In previous work a twin disc approach has been used to study the effect of sand (used to improve adhesion) and leaves on wheel/rail isolation. Friction modifiers are of significant current interest in wheel/rail research. Introducing a new material into the tread/top of rail interface can raise questions about the impact on signalling systems. Although no significant effects have been observed in practical operation on a range of railway systems, the intention in this work was to evaluate conductance between wheel and rail in a more controlled and systematic fashion using the previously established methodology. Using the twin disc technique, friction modifier, in the form of a solid stick, was applied using a spring loaded device to the rotating wheel disc to generate a visible film. Tests were run to measure contact impedance at typical loads and slips. Static tests were also carried out using discs pre-conditioned with a friction modifier film. The electrical circuit used was a modified simplified simulation of audio frequency track circuit. No significant difference was observed in the measured impedance for dry conditions with no friction modifier, versus tests where friction modifier was applied, regardless of percentage slip or input voltage. The analysis suggests that the introduction of friction modifier into the existing wheel/rail interfacial film does not result in increased impedance with all other factors being equal.

MODELING THE IMPACT OF AWARENESS CREATED BY MEDIA CAMPAIGNS ON VACCINATION COVERAGE IN A VARIABLE POPULATION

2014 ◽  
Vol 22 (02) ◽  
pp. 249-270 ◽  
Author(s):  
ANUPAMA SHARMA ◽  
A. K. MISRA
Keyword(s):  
Hepatitis B ◽  
Vaccination Coverage ◽  
Total Population ◽  
Hepatitis B Vaccination ◽  
Preventive Strategy ◽  
Successful Implementation ◽  
Global Public Health ◽  
Media Campaigns ◽  
Model Stability ◽  
The Impact

Vaccines are a core component of any preventive strategy designed to ensure the global public health. A major factor influencing the successful implementation of any immunization program is awareness and public acceptance of the vaccine. The present study focuses on potential impacts of awareness created by media campaigns on vaccination coverage of hepatitis B. In this paper, a SIR model with vital dynamics in a population of varying size is investigated, which couples hepatitis B vaccination and awareness created by media within a single framework. It is assumed that media campaigns propagate awareness about measures requisite for escaping the chances of contracting hepatitis B. The awareness created by media motivates people to get vaccinated and attain full immunization against hepatitis B virus. For analyzing the model, stability theory of differential equations is employed. First, equilibria of the system comprising fractions of the population are obtained and their stability behavior is discussed. Then the asymptotic behavior of total population is discussed in detail. Three threshold parameters R0, R1and R2governing the dynamics of infection and total population are also affirmed. The findings of numerical simulations are also in line with analytically obtained results.

Impact of Reverse Osmosis on Southeast Milk Markets

1989 ◽  
Vol 21 (2) ◽  
pp. 63-75
Author(s):  
William A. Schiek ◽  
Emerson M. Babb
Keyword(s):  
Reverse Osmosis ◽  
Network Flow ◽  
Raw Milk ◽  
Milk Products ◽  
Product Pricing ◽  
Flow Algorithm ◽  
Marketing Orders ◽  
New Processing ◽  
Milk Marketing ◽  
The Impact

AbstractThe Southeast is a net importer of milk and milk products. Milk must be imported from other regions at certain times of the year. Reverse osmosis (RO) is a new processing technology which could significantly reduce milk transportation costs between regions by removing half the water from raw milk prior to shipment. A network flow algorithm, which incorporates federal milk orders and solves for the least cost procurement pattern, was used to assess the impact of RO on southeast milk marketing orders under alternative raw product pricing scenarios.

scholarly journals A Railway Scheduling Method using Probabilistic Model Checking

2019 ◽  
Vol 9 (1) ◽  
pp. 6694-6698
Keyword(s):  
Model Checking ◽  
Probabilistic Model ◽  
Probabilistic Model Checking ◽  
Railway Transportation ◽  
Railway Network ◽  
Double Line ◽  
Arrival Times ◽  
Scheduling Method ◽  
Prism Model ◽  
The Impact

Trains scheduling is an important problem in railway transportation. Many companies use fixed train timetabling to handle this problem. Train delays can affect the pre-defined timetables and postpone destination arrival times. Besides, delay propagation may affect other trains and degrade the performance of a railway network. An optimal timetable minimizes the total propagated delays in a network. In this paper, we propose a new approach to compute the expected propagated delays in a railway network. As the main contribution of the work, we use Discrete-time Markov chains to model a railway network with a fixed timetable and use probabilistic model checking to approximate the expected delays and the probability of reaching destinations with a desired delay. We use PRISM model checker to apply our approach for analyzing the impact of different train scheduling in double line tracks.

scholarly journals Performance analysis of the working surface of the rails from test batches on the Test Loop of JSC “VNIIZhT”

2018 ◽  
Vol 77 (3) ◽  
pp. 141-148
Author(s):  
M. Yu. Khvostik ◽  
I. V. Khromov ◽  
O. A. Bykova ◽  
G. A. Beresten’
Keyword(s):  
Wear Resistance ◽  
Operating Time ◽  
Operating Conditions ◽  
Continuous Change ◽  
Wear Area ◽  
Railway Network ◽  
Operational Conditions ◽  
Rolling Surface ◽  
Test Loop ◽  
The Impact

The monitoring of railway rails damage on the railway network of the JSC “Russian Railways” as well as operational and polygon tests are conducted with the purpose of assessing the impact of operating conditions on the intensity of rails damage, obtaining initial data for forecasting rails failures. The increased intensity of rails wear on sites with a complex plan and profile leads to the fact that with a continuous change from the track, rails which have an underutilized service life of more than 20 % are retrieved. Polygon tests on the Test Loop of the JSC “VNIIZhT” near the Scherbinka station can provide the repeatability and reliability of the results, comparative tests are carried out under identical conditions and their duration is several times less than when tested at experimental sites under operational conditions. The results of the polygon tests of new differentially heat-strengthened rails did not reveal any advantages in the wear resistance of special purposed rails (laid in the recommended radius of the curve for its application) when comparing the rails of domestic manufacturers. Metal shelling out on the rolling surface of rails is the main reason for the removal of rails from test batches. The origin and development of defects of this kind is due to both violations of the technology of manufacturing rails, and because of violations of the current maintenance of the track. The metal stock in the area of the rail head of R65 type due to the increase in its dimensions positively affects the extension of the lifetime of the rails, reducing the cost of the life cycle and the rail itself, and the design of the track as a whole. When carrying out a separate study in order to obtain results characterizing the stability of high-quality rails to contact fatigue damage, it is advisable to optimize the conditions of the polygon tests, bringing them closer to operational ones. When forming the test results, it is necessary to expand the list of criteria for assessing the wear resistance of rails, supplementing it with the size of the wear area at the time of a certain operating time of the tonnage, with the introduction of this criterion into the appropriate methods for the polygon (operational) tests.

scholarly journals Impact of fractional order methods on optimized tilt control for rail vehicles

2017 ◽  
Vol 20 (3) ◽  
Author(s):  
Fazilah Hassan ◽  
Argyrios Zolotas
Keyword(s):  
Fractional Order ◽  
High Speed ◽  
Control Design ◽  
Ride Quality ◽  
Dynamic Interactions ◽  
High Speed Rail ◽  
Control Applications ◽  
Railway Systems ◽  
Methods Analytical ◽  
The Impact

AbstractAdvances in the use of fractional order calculus in control theory increasingly make their way into control applications such as in the process industry, electrical machines, mechatronics/robotics, albeit at a slower rate into control applications in automotive and railway systems. We present work on advances in high-speed rail vehicle tilt control design enabled by use of fractional order methods. Analytical problems in rail tilt control still exist especially on simplified tilt using non-precedent sensor information (rather than use of the more complex precedence (or preview) schemes). Challenges arise due to suspension dynamic interactions (due to strong coupling between roll and lateral dynamic modes) and the sensor measurement. We explore optimized PID-based non-precedent tilt control via both direct fractional-order PID design and via fractional-order based loop shaping that reduces effect of lags in the design model. The impact of fractional order design methods on tilt performance (track curve following vs ride quality) trade off is particularly emphasized. Simulation results illustrate superior benefit by utilizing fractional order-based tilt control design.

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