bluuebunny/crossref_metadata_2025 huggingface dataset:
A Cooperative Scheduling Model for Subway Trains
Authors: Li Xiang , Yang Xin , Wang Hongwei , Su Shuai , Sun Wenzhe
Published: July 2013

For subway systems, the energy put into accelerating the trains can be reconverted into electric energy by using the motors as generators during braking phase. Generally speaking, except a small part is used for on-board purposes, most of the recovery energy is transmitted backwards along the conversion chain and fed back into the catenary. However, since the low catenary voltage DC systems, the transmission losses are very high. In order to improve the utilization of recovery energy, this paper proposes an optimization approach to cooperate the acceleration and brake times of successive trains such that the recovery energy from the braking train can be directly used by the accelerating train. First, we formulate a quadratic programming model to optimize the cooperative degree with trip time constraint and time window constraints. Furthermore, we solve the optimal solution by using the Kuhn-Tucker conditions. Finally, we present a numerical example based on the operation data from Beijing Yizhuang subway line of China, which illustrates that the proposed model can improve the cooperative degree by 9.08%.
Estimation of Track Irregularity Based on Genetic Algorithm and Unscented Kalman Filtering
Authors: Shi Hongmei , Yu Zujun
Published: July 2013

Track irregularity is the main excitation source of wheel-track interaction. Due to the difference of speed, axle load and suspension parameters between track inspection train and the operating trains, the data acquired from the inspection car cannot completely reflect the real status of track irregularity when the operating trains go through the rail. In this paper, an estimation method of track irregularity is proposed using genetic algorithm and Unscented Kalman Filtering. Firstly, a vehicle-track vertical coupling model is established, in which the high-speed vehicle is assumed as a rigid body with two layers of spring and damping system and the track is viewed as an elastic system with three layers. Then, the static track irregularity is estimated by genetic algorithm using the vibration data of vehicle and dynamic track irregularity which are acquired from the inspection car. And the dynamic responses of vehicle and track can be solved if the static track irregularity is known. So combining with vehicle track coupling model of different operating train, the potential dynamic track irregularity is solved by simulation, which the operating train could goes through. To get a better estimation result, Unscented Kalman Filtering (UKF) algorithm is employed to optimize the dynamic responses of rail using measurement data of vehicle vibration. The simulation results show that the estimated static track irregularity and the vibration responses of vehicle track system can go well with the true value. It can be realized to estimate the real rail status when different trains go through the rail by this method.
The Application of the Time Series Theory to Processing Data From the SBAS Receiver in Safety Mode
Authors: Jonas M.
Published: July 2013

Before satellite-based augmentation systems (SBAS) such as the Wide Area Augmentation System (WAAS) in the USA, and the European Geostationary Navigation Overlay Service (EGNOS), will be used in railway safety-related applications, it is necessary to determine reliability attributes of these systems as quality measures from the user’s point of view. It is necessary to find new methods of processing data from the SBAS system in accordance with strict railway standards.

For this purposes data from the SBAS receiver with the Safety of Life Service was processed by means of the time series theory. At first, a basic statistic exploration analysis by means of histograms and boxplot graphs was done. Then correlation analysis by autocorrelation (ACF), and partial autocorrelation functions (PACF), was done. Statistical tests for the confirmation of non-stationarity, and conditional heteroscedasticity of time series were done. Engle’s ARCH test confirmed that conditional heteroscedasticity is contained. ARMA/GARCH models were constructed, and their residuals were analyzed.

Autocorrelation functions and statistical tests of models residuals were done. The analysis implies that the models well cover the variance volatility of investigated time series and so it is possible to use the ARMA/GARCH models for the modeling of SBAS receiver outputs.
Monitoring the Stress Free Temperature of a Complex Segment of Track
Authors: Harrison Harold D. , Cheng Li , Wang Dawei , Li Jianhua
Published: July 2013

A 1.25 km segment of a heavy haul coal line was instrumented with Rail Stress Monitors (RSM) [1–7] and monitored throughout a winter-summer swing in ambient conditions. The track segment included a reverse curve spanning elevated, at-grade, and tunnel conditions that transitioned to a turnout. Natural events along with track maintenance activity punctuated the seasonal shifts in Stress Free Temperature (SFT).
Design of Wind-Break Fences for Railway Applications
Authors: Cheli F. , Ripamonti F. , Schito P. , Tomasini G.
Published: July 2013

The train overturning risk associated to strong crosswinds can be reduced by putting wind break fences along the line. This paper proposes a procedure to determine the loads acting on the barriers, starting from CFD analysis, experimental wind tunnel tests and standards requirements. In particular, two external action on the fences are considered: the pressure loads induced by the passage of the train and the loads due to the natural wind. Static and dynamic loads have been analyzed. Through the definition of extreme events both static and fatigue verification have been carried out on the structure.
Implementing New Automated Ticketing Technology at Virginia Railway Express
Authors: Henry Chris , Grant Steven
Published: July 2013

Virginia Railway Express (VRE) is at a crossroads at a key time with its current technology. In the near future, VRE will be required to replace its existing Automated Fare Collection (AFC) system. While this may not initially sound so different from what all rail agencies must eventually go through, ensuring that the system can be integrated into its neighboring Washington Metropolitan Area Transit Authority’s (WMATA) impending New Electronic Payments Program (NEPP) is a completely different story, and for many reasons.

VRE is a key regional partner of WMATA and, as such, the two work hand-in-hand to ensure the interoperability between the two systems is maximized for the passengers who ride both services. Key to this is NEPP as an eventual replacement of WMATA’s SmarTrip® program. Since the majority of VRE’s ridership is Federal employees who carry PIV (Personal Identity Verification)/CAC (Common Access Card) cards and are making their way into the nation’s capital from Virginia and Maryland, the SmarTrip® program has been a major focus for VRE.

While the NEPP program has several years before it goes live, it presents VRE with a valuable opportunity to review its current AFC system and use the interim to implement various concepts of operations for a future system. As such, VRE has become a willing partner for WMATA as a host for technology proof-of-concepts that will aid both VRE and WMATA in the long term.

VRE is looking into hosting various technology options to pilot at key stations that may include mobile ticketing, Near Field Communication (NFC), or PIV/CAC cards as forms of payment, as well as proof of payment. As an open-gated system, VRE must tackle the problem of fare evasion, so looking to maximize its proof-of-payment capabilities with the latest technology is key.

VRE would like to share with the rail community its thoughts and ideas for proof-of-concepts to utilize the latest payment technologies, as well as discuss its plans on interoperability with WMATA to assist agencies with similar challenges.
Emissions Testing of an Intercity Passenger Locomotive Operating on B20 Biodiesel Fuel
Authors: Shurland Melissa , Deitchman Roy , Smith Wade
Published: July 2013

The emissions of a GE P-32 passenger locomotive was not adversely impacted by the use of B20 biodiesel blended fuel. Amtrak, with the support of the Federal Railroad Administration operated a P-32 passenger locomotive in revenue service for a period of 12 months, operating on a blend of 20% pure biodiesel and 80% #2 ultra low sulfur diesel (ULSD) fuel. The P-32 locomotive used in the biodiesel demonstration was a Tier 0 12-cyclinder engine, built in 1991. The locomotive was operated on the Heartland Flyer route, providing passenger train service between Oklahoma City, OK and Fort Worth, TX. The biodiesel test locomotive maintained the Heartland Flyer train schedule 331 times by providing one roundtrip daily between the two cities, for a total of 410 miles.

Following the in-service trial, the locomotive underwent emissions testing at the GE Transportation’s locomotive emissions test facility in Erie, PA. The locomotive was tested according to the US Code of Federal Regulation (CFR) Title 40 Part 92. The test results show that operating the P-32 passenger locomotive on B20 biodiesel blended fuel for 12 months did not adversely affect the emissions of the locomotive. The paper will outline the procedure and results from the emissions testing of the B20 fuel in a passenger locomotive engine, after having used B20 fuel for 12-months in revenue service. The paper will show that the locomotive B20 emissions for hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx) particulate matter (PM), and smoke opacity were not adversely affected, and were well below the EPA locomotive emissions limit.

Due to warranty issues, GE permitted use of B20 for this study however GE does not approve use of B20 under its warranty provisions.
Investigation and Mitigation of Differential Movement at Railway Transitions for US High Speed Passenger Rail and Joint Passenger/Freight Corridors
Authors: Tutumluer Erol , Stark Timothy D. , Mishra Debakanta , Hyslip James P.
Published: July 2013

As with most highway bridges, railway transitions experience differential movements due to differences in track system stiffness, track damping characteristics, foundation type, ballast settlement from fouling and/or degradation, as well as fill and subgrade settlement. This differential movement is especially problematic for high speed rail infrastructure as the “bump” at the transition is accentuated at high speeds. Identification of different factors contributing towards this differential movement, as well as development of design and maintenance strategies to mitigate the problem is imperative for the safe and economical operation of both freight and passenger rail networks. This paper presents the research framework and preliminary findings from a recently initiated research effort at the University of Illinois at Urbana-Champaign. Aimed at developing design and repair techniques to mitigate differential movement at railway transitions, this research project involves instrumentation, performance monitoring and numerical modeling of new and existing track transitions.
Preserving and Protecting Freight Infrastructure and Routes
Authors: Meitzen Mark E. , Loftus-Otway Lisa , Grow Robert J. , Hutson Nathan M. , Bruening Ari D. , Phillips Ron
Published: July 2013

A smoothly functioning freight transportation network is part of the nation’s critical infrastructure and is essential to the operation of the U.S. economy. Rail is a significant component of this infrastructure. There are serious threats to American’s freight rail system caused in large part by intrusion of incompatible land uses, especially in America’s burgeoning megapolitans. Population growth, rising incomes, and other aspects of economic growth have all led to increased competition for the land resources around the freight rail network. Incompatible land uses around freight rail corridors and facilities often results in conflicts between those uses and barriers to efficient freight transportation.

This paper discusses the research results from Transportation Research Board (TRB) Project NCFRP 24 that developed a website, www.EnvisionFreight.com, and a report outlining tools and strategies for better planning and design of residential and other structures in proximity to freight corridors and facilities. The paper initially discusses the benefits and importance of an integrated multimodal freight system, and the value of a smoothly functioning freight transportation network. This includes discussion of the freight rail network’s part in the nation’s critical freight transportation infrastructure. The paper then reviews the conflicts and barriers that often occur between incompatible land uses and freight rail assets. Case studies that were conducted during the research are also utilized to show current practices in planning for freight. Finally the paper discusses strategies for preserving and evolving the network of freight rail corridors and access points, which requires foreseeing future areas of conflict and acting proactively in an economically rational manner.

Our research found four areas of tools and preservation and protection strategies to minimize and resolve conflicts between freight and other land uses: long-range planning, zoning and design, mitigation, and education and outreach. The research found that tremendous potential exists to significantly affect decision making that impacts freight. With the likely emergence of freight mega-regions that do not respect state or even national boundaries, a new planning dialogue is required to prepare for the next generation freight system to support these regions. Planning decisions that will be made over the next decade will be critical to our future transportation system efficiencies and regional competitiveness. Local and regional freight planning in this context will require highly skilled freight transportation planners, new planning strategies and tools, community support, longer-term regional visioning, and legislative authority.
Developments in Traction Transformer
Authors: Sarkar Subhas
Published: July 2013

Mass transit systems are gaining increased attention and popularity in the country. With this increased activity, more and more lines are getting added under public transit systems in more and more cities. One of the essential elements in the transit system is the traction transformer which powers the trains. With the emphasis on reliability, there is also increased awareness of the energy efficiency required of the traction substation equipments and the transformer in particular.

Traction transformers are not ordinary power or distribution transformers. They have to meet several special requirements, including parameters like voltage regulation, impedance, commutation, short circuit withstand, operation with rectifiers, harmonic losses, wide fluctuation of load currents depending on the cyclic nature, etc. The reliability criteria are stringent and the traction transformers have to be properly designed, manufactured and tested, including short circuit testing for validation.

Use of modern design tools like electric and magnetic field mapping and estimation of forces and stresses are helpful in computing them accurately.

With the extensive use of vacuum circuit breakers, the subject of interaction of transformers and breakers have come to the foreground. New standards (like IEEE C57.142) have come into existence, which recommend methods to mitigate such effects. The author of this paper and his team has successfully applied these techniques in real life situations to solve problems.

Work is in the final stages for preparation of a standard specifically for Traction Power Rectifier Transformers for transit applications (IEEE draft standard 1653.1) under the IEEE Vehicle Standards Committee.
Laboratory Investigation of the Abrasive Wear Mechanism of Concrete Crosstie Rail Seat Deterioration (RSD)
Authors: Shurpali Amogh Arvind , Van Dam Emily , Edwards J. Riley , Lange David A. , Barkan Christopher P. L.
Published: July 2013

Currently, there are divergent design and performance demands on railway infrastructure components due to increasing freight axle loads and cumulative gross tonnages, as well as increased investment in high-speed passenger rail development in North America. The divergence in loading and performance demands on shared infrastructure arises from the fact that while high-speed passenger trains exert lower loads at relatively high speeds, freight trains exert high loads at relatively low speeds. Improvements in infrastructure component designs are needed to achieve increased durability and tighter geometric tolerances. According to a rail industry survey administered by University of Illinois at Urbana-Champaign (UIUC) in 2008, Rail Seat Deterioration (RSD) is the principal performance problem limiting the service life of concrete crossties in North America. Rail infrastructure researchers and industry experts agree that abrasive wear may occur due to relative motion between the rail pad and concrete crosstie rail seat, potentially resulting in RSD. The complex tribological process of abrasion is further complicated and expected to be accelerated by the presence of abrasive fines and moisture, creating 3-body wear condition. Lack of understanding of the abrasion mechanism has resulted in a sub-optimal and iterative design of ties, causing reduced service life. This paper summarizes our efforts in understanding the effect of changing the mix design of concrete on the abrasion resistance of the rail seat which will eventually help us in modeling abrasive wear in RSD by constructing a mathematical relationship between the rail seat wear rate and input parameters including concrete mix design, mechanical/tribological properties of materials involved, normal load applied, presence of moisture, and abrasive fines. To simulate abrasive wear in RSD, a simple experiment is being carried out using a rotating wheel (lapping machine) capable of abrading concrete samples as a part of UIUC’s Small-Scale Abrasion Resistance Test (SSART). The objective of this research is to develop wear performance curves (e.g. wear depth versus load/time/cycles) for lab specimens developed from concrete crosstie mix designs that are currently being used in the industry, as well as for the evaluation of new mix designs. These data will help the rail industry in mechanistically designing concrete crossties by improving the understanding of materials used for concrete crosstie mix designs, with the objective of decreasing life cycle costs for the crosstie and fastening system. Preliminary SSART results are in agreement with relevant literature documenting the relationships between concrete mix designs and curing conditions and the resulting rate of abrasion.
Positive Train Control: Where Are We, and What Next?
Authors: Patel Dilip M. , Callen Joshua C.
Published: July 2013

Positive Train Control (PTC) must be up and running by December 2015. Railroads have already submitted their Implementation Plans, identifying the type of PTC system each plans to use. Every one of these systems must have Type Approval from FRA before being placed in service. To date, three different systems have gained Type Approval. Others are at various points in the Type Approval process.

This paper will provide the train control background, starting with where we were and how we got where we are with PTC mandate. The paper will survey the systems that have been approved or are in the process. For each, an overview of the technology will be provided, along with an assessment of the current state of development and the work that is needed to get to the finish line. Issues of interoperability and radio spectrum use will be highlighted.

Finally, an assessment of the “big picture” will be offered, including the roles of railroads, suppliers, and regulators.
Engineering Approach to Weld Repairs for Bogie (Truck) Frames
Authors: Pearson John B. , Janiszewski John A. , Nelson Travis M.
Published: July 2013

As welded rail car truck (bogie) frames become more common than cast frames and as they accumulate more service time and mileage, increasing numbers of service-induced defects are bound to occur. Some items requiring repair or rehabilitation include cracks, accident damage, excessively worn surfaces, and modifications for addition of equipment or mounting brackets. Bogie frames are structural components exposed to severe static and dynamic loads and hence repairs and modifications must consider all aspects of performance. This paper reviews a methodology used by LTK Engineering Services to determine root causes of service-induced defects and to subsequently qualify repairs and modifications to allow the bogie frames to meet their design operating lifetime. The method includes analyses of both the material and the failure itself, to confirm the adequacy of the frame material and to identify the design or fabrication factor(s) contributing to the development of cracks. Stress analysis of varying complexity is utilized to confirm the crack initiation and propagation causes as well as to screen potential repair approaches.
Moving Away From Diesel and Towards All-Electric Locomotives in North America: Planning and Logistics of Ultra-Capacitor/Battery Technology
Authors: Boozarjomehri E. , Morrison E. , Roth I. , Lovegrove G.
Published: July 2013

This paper analyzes alternatives to carbon-based fuels, including ‘clean’ electric locomotive technology. Electrification of the North American railway network leaves many questions to be researched, such as: sufficient power capacity, ‘clean’ sources, distribution costs, infrastructure costs, logistics issues, legislative barriers, and resulting changes to business practises. A comprehensive review of incentives, logistics, and barriers was done to shed some light on emerging research needs to fill knowledge gaps in time to sustain industry competitiveness, and to meet the demands of a more sustainable future for North American freight, commuter, and tourism rail.

Given prohibitively high costs and logistics of rail electrification, North American researchers have started focusing on ultra-capacitors and batteries. Previous research suggests that a hybrid capacitor/battery equipped locomotive would work, all within the existing envelope of locomotive chassis, and with much lower infrastructure costs. The transition in NA would be faster, at a much lower cost, including high speed passenger rail. However, no one has yet done the necessary research to verify this hypothesis.
The Role of Oxidation in Railroad Wheels
Authors: Dedmon Steven L.
Published: July 2013

On-tread braking generates high heat and often results in temperatures on the tread surface in excess of 400C (750F). Temperatures this high result in rapid oxidation of the tread surface. High temperature oxidation for steel generally follows a parabolic rate law: the time to generate a given weight or thickness of an oxide layer increases proportionately to the square of the weight or thickness of that oxide layer. The decrease in the rate of generation of new scale thickness results from the longer time it takes for oxygen to diffuse through an increasingly thicker layer of oxide. However, wheel/rail contact and abrasive action from the brake pad often erodes the oxide layer as it forms, accelerating the rate of formation of the oxide. Further, as the oxide forms, cold worked tread material from rolling contact forces is removed thereby reducing the beneficial residual stresses and higher hardness layer that may have protected the tread surface from further plastic deformation. Environmental factors may also aggravate oxidation losses sufficiently to make it a primary rather than a secondary cause of wear.

High temperature oxidation can contribute to an accelerated rate of shelling, which can result from oxide forming within tread cracks. Tensile stresses at the crack tip are caused by expansion when the oxide forms.

Compressive stresses in the oxide are usually minimal, as expansion is not constrained in the scale growth direction. Volume constraints within a crack when the oxide forms generates compressive stresses in the newly formed oxide, which results in wedging forces at the crack tip.

Oxidation of the tread surface may permit debris to adhere to the tread surface creating a defect called “built-up tread”. Although built-up tread defects require other factors in order to become a problem, oxidation of the tread surface appears to be an initiating mechanism.

Results from experimentation and Finite Element Analyses are used to support this work.
Results From the 2011 Hiawatha Service Passenger Study
Authors: Sperry Benjamin R. , Morgan Curtis A.
Published: July 2013

The Hiawatha Service is an Amtrak intercity passenger rail service operating a 90-mile route between Milwaukee, Wisconsin and Chicago, Illinois. The route has experienced a steady growth in ridership in recent years, carrying more than 815,000 passengers during the 12-month period ending September 2011. Owing to the route’s trip-time competitiveness with the automobile, frequent daily service, an intermodal connection with the airport in Milwaukee, and the multi-state funding partnership between the states of Wisconsin and Illinois, the Hiawatha Service is a model of how passenger rail can be an integral part of the multimodal transportation system in an intercity corridor. In January 2011, researchers from the Texas Transportation Institute (TTI) passenger rail research group, with financial support from the University Transportation Center for Mobility (UTCM) and in partnership with the Wisconsin Department of Transportation (WisDOT), initiated a research project to examine the mobility impacts of the Hiawatha Service intercity passenger rail route. One of the major elements of this research project was an on-board survey of Hiawatha Service passengers, implemented in Spring 2011.

This paper reports a summary of selected findings from the 2011 TTI/WisDOT Hiawatha Service passenger survey. The survey obtained valuable information about the current passengers, including data on passenger trip purpose, activities before and after the rail trip, travel alternatives to the Hiawatha Service if the route was not available, motivations for choosing rail for the trip, the impact of potential service changes on increasing ridership, and demographic profile data. A majority of passengers traveling on weekdays were regular commuters or business travelers while personal trips are dominant on weekends. Nearly 70 percent of passengers would drive if the rail service was not available, suggesting that the Hiawatha Service plays a critical role in relieving highway congestion in the region. The results of this study can be used by public agency planning staff and policymakers to guide the development of new intercity passenger rail services in similar corridors across the U.S.
Rail Transportation Energy Efficiency-Oriented Technologies
Authors: Alexander Pamela E.
Published: July 2013

Rail transportation is playing a very important role in the effort to keep the world’s expanding major cities safe and mobile. Travel by rail can move people and cargo with higher levels of energy efficiency, greater safety, lower cost and greater reliability than any other mode of transportation. On average, trips by train can generate between one third and one fifth of the carbon dioxide (CO2) produced by the equivalent automobile or airplane travel. Environmental awareness plus reduced operating costs are primary considerations in decision making for new transit programs around the globe.

Energy consumption is a major part of rail operation costs and has been at the focus of rail systems sustainability initiatives. The majority of energy consumed by metropolitan and urban rail systems is used to move the trains. In recent years, energy saving technologies for rail vehicle power systems have been implemented on many rail systems worldwide. Improving railway energy efficiency results in not only a reduction in energy consumption and cost, but also a reduction in pollution due to power generation. In an effort to promote environmental quality and energy efficiency, energy usage in rail systems is analyzed to identify new technologies, developments, and procedures for increased efficiency. This paper provides an overview of the various strategies and solutions used to increase energy efficiency in rail systems and highlights the key technologies needed for their implementation.
Railway’s Impact on Regional Socio-Economic Systems: Impact Degree Evaluation—A Case Study of Beijing-Shanghai Existing Line
Authors: Li Xuemei , Liang Dandan , Zhou Yaodong
Published: July 2013

This article establishes railway’s impact aggregative indicators by using Correlation Analysis and Principal Component Analysis. With the correlative data of Beijing-Shanghai existing line from 2000 to 2008, the paper evaluates the level of railway’s impact on regional socioeconomic systems through Data Envelopment Analysis (DEA) method. According to the DEA results, it can be divided into three levels: first level is Beijing and Shanghai; second is Tianjin, Jiangsu and Shandong; and the third is Hebei and Anhui. The results of this paper could be used as references for the future planning and operational management of Chinese railway network: (1) Railway’s influence on the starting and end station is stronger than that on the intermediate stations. In view of this, more railways or higher technical railways could be considered to build in the higher impact areas; (2) In order to meet the needs of passenger and freight transport, it’s better to separate passenger and freight lines; (3) Although the overall influence is lower at the middle stations, the impact on the systems of resource and environment is high.
Sequence Optimization for Timetabling High Frequency Passenger Trains
Authors: Abbas-Turki A. , Grunder O. , El Moudni A. , Zaremba E.
Published: July 2013

Recently, Harrod has revealed that the occupancy constraints are not sufficient to timetable rail traffic. This insufficiency occurs when opposite movements of trains share the same route. In this paper, we propose a quick algorithm that considers overtaking and opposite train’s movements. This algorithm builds a train timetable from a proposed sequence of trains. It is based on an elementary model of an invariant resource sharing system. The algorithm is proposed in order to extend the genetic algorithm that calculates the sequence of trains for maximizing the frequency of passenger’s train.
Potential Sources of High-Speed Rail Civil Infrastructure Cost Reduction
Authors: Zicha Jan H.
Published: July 2013

High-speed rail infrastructures support the fastest and safest passenger ground transportation mode in existence. Since these infrastructures represent a major achievement of human ingenuity, they are expected to be exceptional. However, the cost of high-speed rail infrastructure does not have to mirror such exceptional status under all circumstances. Well documented yet underutilized civil engineering concepts and features exist that carry considerable cost reduction potentials. They are based on experience with strategic project structuring, appreciation of dynamic track/train interaction trends that control high speed movement, maintenance experience, and component testing. Their utilization is often contingent upon engineering necessary to perform adjustments due to specific conditions, and on availability of verification testing to overcome the established status quo.

This article is based on practical consulting and operational experience. The presented issues include concepts of cost-effective positioning of civil engineering subsystems in a high-speed rail project, detection and avoidance of cost-rising zones by alignment selection, trackwork geometries and structural features justifying major reductions of horizontal radii, cost-effective selection and use of slabtrack, and cost minimization steps recommended in high-speed rail tunnel design. Supportive theoretical backgrounds exist; however, their presentation would require several papers.
Model Reference Adaptive Control of Train Dynamic Braking
Authors: Ahmad Husain , Ahmadian Mehdi
Published: July 2013

Model Reference Adaptive Control (MRAC) is developed to control the amount of current through the traction motors under various wheel/rail adhesion conditions while braking. More accurate estimation and control of train braking distance will allow the trains to be run with closer spacing. In order to minimize the braking distance of a train, dynamic braking forces need to be maximized while maintaining good wheel/rail adhesion. Wheel/rail adhesion coefficient plays an important role in safe train braking. Excessively large dynamic braking can cause wheel lockup that can damage the wheels and the rail. In addition, it can cause large buff loads that cause derailment or coupler damage. Dynamic braking force is directly proportional to the current supplied to the traction motors. In this study, a multibody formulation of a locomotive and three railcars is used to develop a model reference adaptive controller for adjusting the current provided to the traction motors such that the maximum dynamic braking is achieved, without wheel lockup. Aerodynamic drag and air brake forces are included in the model. The coupler forces are also considered in the control model to ensure that they remain within acceptable levels. The results indicate that the MRAC system significantly improves braking distance while maintaining better wheel/rail adhesion and coupler dynamics during braking.
Warrants for Active Warning Devices at Low-Volume Highway-Rail Grade Crossings
Authors: Kunisetty Jaya Lakshmi , Weissmann Angela Jannini , Weissmann Jose , Yang Mijia , Venglar Steven P.
Published: July 2013

The main objective of this research is to reduce the number of crashes between vehicles and trains at low-volume passive highway-rail at grade crossings by developing a revised safety index and warrants for active warning devices in the state of Texas. The research is focused only on low-volume crossings because most high-volume crossings in the state of Texas have already received improvements in terms of traffic control devices as the existing Texas priority index prioritizes high-volume crossings.

This technical paper will describe and provide the most up-to-date preliminary results for warrants of the first year study in a two year Texas Department of Transportation (TxDOT) 0-6642 project called “Developing Warrants for Active Warning Devices at Low-Volume Highway-Rail Grade Crossings.” In order to prioritize the crossings that meet warrants a priority index should be used. The current Texas priority index places more emphasis on high-volume crossings with crash history and it doesn’t include several important variables. In order to address the issues of the current Texas priority index a new Texas Passive Crossing Index was developed based on a different concept — instead of using numeric thresholds, cumulative percentiles of the relevant variables are used.
Contact Patch Comparison Between a Roller Rig and Tangent Track for a Single Wheelset
Authors: Taheri Mehdi , Ahmadian Mehdi
Published: July 2013

This study compares contact patch size for a single wheelset when operated on a roller rig with what occurs on a tangent track, using SIMPACK, a multi-body dynamics software. The primary purpose of the study is to determine if one is able to use a roller rig to duplicate and evaluate the contact patch dynamics that occur on a tangent track. The ability to evaluate the contact patch dynamics on a roller rig provides the significant advantage of conducting tests in the controlled environment of laboratory, to more accurately measure the constants that are commonly needed for creepage models, such as Kalker’s. The wheelset is modeled as a 6 degrees of freedom (unconstrained) body for the tangent track study. The Wheelset is constrained longitudinally for the roller rig simulations. The wheel-rail interface is modeled using the options available in SIMPACK, which are based on Kalker’s empirical creepage model. The simulation data is exported into Matlab for further analysis of the contact patch size. The study suggests that it is possible to use a constant scaling factor for relating the contact patch size on a roller rig with a tangent track, using the constrained contact method. For the elastic contact method the contact patches cannot be related to each other through a constant. In that case, a formula is needed to relate the two contact patches.
Development of a Portable Internal 3D Rail Flaw Imaging System
Authors: Saadat Soheil , Rolin Amaury , Radzevicius Stanley , Al-Nazer Leith , Carr Gary
Published: July 2013

Internal rail flaws continue to present a significant issue for the railroad industry. Current practices to mitigate the risk of catastrophic failure of the rails involve inspection for internal flaws and cracks using ultrasonic rail flaw detector technology, usually employed on rail-based vehicles. Following the identification of a suspected defect by an inspection vehicle, a detailed inspection of the suspect area is usually conducted to confirm the presence of the defect prior to the remedial action. Current portable or ultrasonic devices require significant expertise to allow test personnel to make a good judgment regarding the presence and severity of the flaw. A new generation of handheld detector is being developed to provide accurate three-dimensional images of the suspected flaw, thereby eliminating uncertainties in the inspection and providing operators with accurate sizing and orientation information. This paper presents a prototype ultrasonic handheld rail flaw inspection device designed and developed through support provided by the Federal Railroad Administration’s Office of Research and Development by ENSCO, Inc., which can produce accurate three-dimensional images of suspected flaws for verification and characterization proposes.
A Human Factors Investigation Into the Unavailability of Active Warnings at Railway Level Crossings
Authors: Gildersleeve Matthew , Wullems Christian
Published: July 2013

This paper discusses human factors issues of low cost railway level crossings in Australia. Several issues are discussed in this paper including safety at level railway crossings, human factors considerations associated with the unavailability of a warning device, and a conceptual model for how safety could be compromised at railway level crossings following prolonged or frequent unavailability.

The current paper summarises and extends pertinent literature that must be considered for effective interventions to improve safety and to advance our theoretical understanding of human behaviour at level crossings. Although the results of our research are not presented, we describe our experimental approach to progress the current lack of knowledge in this area. In particular we highlight where we can improve previous research methodology (independent & dependent variables) when investigating right-side failure at level crossings, which can produce results with greater validity and meaning. Our research aims to quantify risk to motorists at level crossings following right-side failure using a Human Reliability Assessment (HRA) method, supported by data collected using an advanced driving simulator. This method aims to identify human error within tasks and task units identified as part of the task analysis process. It is anticipated that by modelling driver behaviour the current study will be able to quantify human reliability. Such a risk assessment for the impact of right-side failure at level crossings is currently absent in the literature. Therefore it is crucial to offer quantification of success and failure of this intricate system. The task analysis allows human error identification for the precursors to risky driving to be achieved. If task analysis is not employed the error reduction method may be unsuitable and eventually unsuccessful.

Our aim is also to determine those contexts that allow the system to operate successfully with the smallest probability of human error. Human behaviour during complex tasks such as driving through a level crossing is fundamentally context bound. Therefore this study also aims to quantify those performance-shaping factors that may contribute to vehicle train collisions by highlighting changes in the task units and driver physiology. Finally we consider a number of variables germane to ensuring external validity of our results. Without this inclusion, such an analysis could seriously underestimate risk.
Vibrational Analysis of a Dual-Motive Locomotive and Evaluation by Experimental Methods and Modal Analysis
Authors: Yugat Jesús Otero , Castellanos Gorka Agirre , Portillo Igor Alonso
Published: July 2013

This paper presents a theoretical and experimental study done on an electro-diesel locomotive in order to evaluate the dynamic behavior of the vehicle in terms of safety, running performance and wheel-track interaction. The vibration analysis has been made by means of different experimental methodologies. The first one consists on the acquisition of accelerations at points located at the wheelset, the truck frame and the coach, using piezorresistive accelerometers. The registered signals allow to validate the locomotive in terms of safety against derailment and running behavior, according the UIC 518 leaflet. The second method is based on the modal analysis theory and includes the dynamic properties estimation under vibrational excitation. This procedure takes into account the determination of modal parameters such as natural frequencies, modal damping ratios and mode shapes, by means of a control hydraulic actuator. The third methodology consists on the operational modal analysis done with the experimental measurements acquired on track tests, in order to validate the results obtained by modal analysis and evaluate the dynamic behavior under different speed ranges and cant deficiencies. Several tests have been done by means of the described methods in an electro-diesel locomotive composed by a primary suspension with dampers and a secondary suspension with rigid stiffness. In addition, two types of dampers have been evaluated with the purpose of optimizing the damping properties of the vehicle’s primary suspension. Through these experimental methods, a useful tool for the prediction and analysis of the dynamic behavior is provided. Additionally, the results obtained by means of these methodologies permit examining the influence of different running conditions and vehicle properties on the modal parameters.
Computational Analysis of Thermal Performance and Entropy Generation of Nanofluid Flow in Microchannels
Authors: Li Jie , Kleinstreuer Clement , Feng Yu
Published: July 2013

High heat loads of mechanical, chemical, and biomedical microsystems require heat exchangers which are very small, robust, and efficient. Nanofluids are dilute suspensions of nanoparticles in liquids, which may exhibit remarkable heat transfer characteristics, especially for heat removal in micro-devices. Minimization of entropy generation is potentially a design tool to determine best heat exchanger device geometry and operation.

Focusing on microchannel heat sink applications, the thermal performance of pure fluid flow as well as different nanofluids (i.e., Al2O3+water and ZnO+EG) with different volume fractions are discussed. The local and volumetric entropy rates caused by frictional and thermal effects are illustrated for different coolants, geometries and operational parameters. The Feng-Kleinstreuer (F-K) thermal conductivity model, which consists of a base-fluid static part, kbf, and a new “micro-mixing” part, kmm, i.e., knf = kbf + kmm, was adopted in the thermal performance study of nanofluid flow in microchannels. In addition, two effective nanofluid viscosity models have been analyzed and are compared in the current study.

In summary, the friction factor, pressure gradient, pumping power, local heat transfer coefficient, thermal resistance and entropy generation are evaluated for different nanofluids. The experimentally validated computational study provides new physical insight and criteria for design applications towards effective micro-system cooling.
Near-Field Thermal Radiation Between Mie Resonance-Based Metamaterials
Authors: Francoeur Mathieu , Basu Soumyadipta , Petersen Spencer J.
Published: July 2013

Near-field radiative heat transfer between dielectric-based metamaterials separated by a sub-wavelength vacuum gap is analyzed. Metamaterials made of silicon carbide spherical inclusions within a dielectric host medium of potassium bromide are considered. We show for the first time that surface polariton mediated near-field radiative heat transfer in both TE and TM polarizations may occur between dielectric-based structures. The results presented in this work also demonstrate that it is possible to engineer materials with designer radiative properties, which is crucial in many emerging energy conversion technologies.
Experimental Investigation on Near Wall Natural Convection With Fluorescent Nanoparticles
Authors: Zhou Leping , Li Yaofa , Yoda Minami , Peterson G. P.
Published: July 2013

The mechanisms of microscale natural convection are yet to be understood for its fundamental characteristics differing from those at the macroscale. The spatial distribution of the fluid velocity in the near wall region, which is crucial to the mechanisms of microscale natural convection, is especially not well understood. An experimental investigation of the spatial velocity and the Brownian diffusion coefficient in the near wall region of a platinum heating wire, 20 micrometers in diameter, was conducted using a multilayer nano-particle image velocimetry (MnPIV) technique. The in-plane velocity of deionized water in the near wall region between a micro heating wire and a glass wall was measured using MnPIV technique with fluorescently tagged polystyrene nanoparticles, 200 nm in diameter. The results indicate that both the magnitude and the deviation of the fluid motion increases with increasing heat flux. The Brownian diffusion coefficient was also calculated and indicates that the Brownian motion in microscale natural convection is important, especially for nanoscale colloidal tracers. The thermophoresis was found to be negligible, even at low heating powers. To enhance the resolution of the fluid motion in the near wall region, it is necessary to use smaller fluorescent nanoparticles as seed tracers.
Modeling of a Nanoparticle Motion in a Newtonian Fluid: A Comparison Between Fluctuating Hydrodynamics and Generalized Langevin Procedures
Authors: Uma B. , Ayyaswamy P. S. , Radhakrishnan R. , Eckmann D. M.
Published: July 2013

A direct numerical simulation adopting an arbitrary Lagrangian-Eulerian based finite element method is employed to simulate the motion of a nanocarrier in a quiescent fluid contained in a cylindrical tube. The nanocarrier is treated as a solid sphere. Thermal fluctuations are implemented using two different approaches: (1) fluctuating hydrodynamics; (2) generalized Langevin dynamics (Mittag-Leffler noise). At thermal equilibrium, the numerical predictions for temperature of the nanoparticle, velocity distribution of the particle, decay of the velocity autocorrelation function, diffusivity of the particle and particle-wall interactions are evaluated and compared with analytical results, where available. For a neutrally buoyant nanoparticle of 200 nm radius, the comparisons between the results obtained from the fluctuating hydrodynamics and the generalized Langevin dynamics approaches are provided. Results for particle diffusivity predicted by the fluctuating hydrodynamics approach compare very well with analytical predictions. Ease of computation of the thermostat is obtained with the Langevin approach although the dynamics gets altered.