bluuebunny/crossref_metadata_2025 huggingface dataset:
From river to shelf, anatomy of a high‐frequency depositional sequence: The Late Pleistocene to Holocene Tiber depositional sequence
Authors: Milli Salvatore , Mancini Marco , Moscatelli Massimiliano , Stigliano Francesco , Marini Mattia , Cavinato Gian Paolo
Published: June 2016

The Late Pleistocene/Holocene Tiber delta succession represents the most recent and one of the best preserved, high‐frequency/low‐rank depositional sequences developed along the Latium continental margin of the Italian peninsula. Several previous studies have established a robust data set from which it has been possible to describe the stratigraphic architecture of the entire Tiber depositional sequence from the landward to seaward sectors and over a distance of 60 km. The Tiber depositional sequence shows many characteristics found in other Late Pleistocene to Holocene deltaic and coastal successions of the Mediterranean area. The stratigraphic architecture of the Tiber depositional sequence is controlled mainly by glacioeustasy, although factors such as tectonic uplift, volcanism and subsidence, exert an influence at a local scale. The resulting depositional model allowed discussion of some important points such as: (1) the genesis of the Tiber mixed bedrock‐alluvial valley, extending from the coastal plain to the innermost portion of the shelf, recording (i) multiple episodes of incision during relative sea‐level fall, and (ii) a downstream increase of depth and width of the valley during the base‐level fall and the subsequent base‐level rise; (2) the different physical expression of the Tiber depositional sequence boundary from landward to seaward, and its diachronous and composite character; (3) the maximum depth reached by the Tiber early lowstand delta at the end of the sea‐level fall is estimated at ca 90 m below the present sea‐level and not at 120 m as suggested by previous works; (4) the backward position of the Tiber late lowstand delta relative to the deposit of early lowstand; (5) the change of the channel pattern and of the stacking pattern of fluvial deposits within the Lowstand Systems Tract, Transgressive Systems Tract and Highstand Systems Tract. All of these features indicate that the Late Pleistocene/Holocene Tiber delta succession, even if deposited in a short period of time from a geological point of view, represents the result of the close interaction among many autogenic and allogenic factors. However, global eustatic variations and sediment supply under the control of climatic changes can be considered the main factors responsible for the stratigraphic architecture of this sedimentary succession, which has been heavily modified by human activity only in the last 3000 years.
Effects of the foot strike pattern on muscle activity and neuromuscular fatigue in downhill trail running
Authors: Giandolini M. , Horvais N. , Rossi J. , Millet G. Y. , Morin J.‐B. , Samozino P.
Published: June 2016

Minimizing musculo‐skeletal damage and fatigue is considered paramount for performance in trail running. Our purposes were to investigate the effects of the foot strike pattern and its variability on (a) muscle activity during a downhill trail run and (b) immediate and delayed neuromuscular fatigue. Twenty‐three runners performed a 6.5‐km run (1264 m of negative elevation change). Electromyographic activity of lower‐limb muscles was recorded continuously. Heel and metatarsal accelerations were recorded to identify the running technique. Peripheral and central fatigue was assessed in knee extensors (KE) and plantar flexors (PF) at Pre‐, Post‐, and 2 days post downhill run (Post2d). Anterior patterns were associated with (a) higher gastrocnemius lateralis activity and lower tibialis anterior and vastus lateralis activity during the run and (b) larger decreases in KE high‐frequency stimulus‐evoked torque Post and larger decrements in KE MVC Post2d. High patterns variability during the run was associated with (a) smaller decreases in KE Db100 Post and MVC Post2d and (b) smaller decreases in PF MVC Post and Post2d. Anterior patterns increase the severity of KE peripheral fatigue. However, high foot strike pattern variability during the run reduced acute and delayed neuromuscular fatigue in KE and PF.
Muscular and neuromuscular control following soccer‐specific exercise in male youth: Changes in injury risk mechanisms
Authors: Lehnert M. , De Ste Croix M. , Zaatar A. , Hughes J. , Varekova R. , Lastovicka O.
Published: June 2016

Poor neuromuscular control has been proposed as a risk factor for non‐contact injuries, thus this study aimed to explore the effects of soccer‐specific fatigue on leg muscle activation, reactive strength, leg stiffness, and functional hamstring/quadriceps ratio (H/QFUNC) in elite male youth soccer players. Outcome measures were determined in 18 youth players (age 14.4 ± 0.5 years; stature 169.4 ± 9.9 cm; mass 59.3 ± 8.9 kg; maturity offset 0.86 ± 0.88 years) pre and post simulated soccer match play (SAFT90). There was no fatigue‐related change in the H/QFUNC; however, reactive strength and leg stiffness were both compromised (P < 0.001) after soccer‐specific fatigue. Muscle activation was also locally compromised (P < 0.001) in the medial hamstring and quadriceps but not in the lateral muscles. Where statistically significant changes were observed, the effect sizes ranged from small to large (0.33–0.97). Compromised stiffness when fatigue is present suggests an increased yielding action, greater ground contact times, greater center of mass displacement, and less efficient movement when the limb comes into contact with the ground. This combined with a reduction in medial quadriceps muscle activation may reflect poor kinetic chain control at the hip and an increase in knee injury risk.
Measuring Children's Church‐Based Social Support: Development and Initial Validation of the Kids’ Church Survey
Authors: Crosby Robert G. , Smith Erin I.
Published: June 2016

Given the importance of considering context in development, the goal of the present study was to develop and provide initial validity evidence for the Kids’ Church Survey (KCS), a new measure of children's church‐based social support. Data were collected from 1253 children ages 6–14 attending mainline Protestant, evangelical Protestant, and Catholic churches. Parallel and exploratory factor analyses supported a three‐factor solution: received (emotional) church support, perceived church support from peers, and perceived church support from adults. Confirmatory models conducted with independent samples provided an excellent fit for the data. All three scales evidenced acceptable internal (.78–.92) and test–retest (.88–.95) reliability. Measurement invariance was demonstrated across genders and age groups, with the exception of the perceived peer support scale, which was not invariant across ages. The KCS was sensitive to between‐church differences in children's programs and incrementally predicted self‐esteem, prosocial behavior, and spirituality. Applications for researchers, mental health practitioners, and clergy are discussed.
Molecular phylogeny and generic‐level taxonomy of the widespread palaeotropical ‘Heteropsis clade’ (Nymphalidae: Satyrinae: Mycalesina)
Authors: ADUSE‐POKU KWAKU , LEES DAVID C. , BRATTSTRÖM OSKAR , KODANDARAMAIAH ULLASA , COLLINS STEVE C. , WAHLBERG NIKLAS , BRAKEFIELD PAUL M.
Published: June 2016

The mycalesine butterfly genus Heteropsis Westwood, 1850 (Satyrinae: Mycalesina) has recently been conceived to be represented in three major palaeotropical regions (Madagascar, Africa and Asia), but there has been no formal taxonomic treatment covering this entire group. Studies aimed at understanding the evolutionary success of Mycalesina in the Old World tropics have been hampered by the lack of both a robust phylogeny and a stable nomenclature for this satyrine subtribe. Here, we present a well‐supported molecular phylogeny based on 10 genes and 133 exemplar taxa, representing almost all known species groups of Heteropsis (s.l.), and including all but four known species in Madagascar. We also combine sequences of the exemplars with a morphological matrix of 428 characters. The widespread ‘Heteropsis clade’ is confirmed as monophyletic, but lineages in different geographic regions also form endemic and well‐supported clades with deep divergences among them. Here we establish this group as comprising three genera, Heteropsis (Malagasy region only), Telinga Moore, 1880 (Asia), and Brakefieldia gen.n. (Africa). We recover the genera Telinga and Brakefieldia as sisters with high support. Each genus is taxonomically characterized and a revised synonymic checklist is appended with new combinations and some changes in rank. With a well‐resolved topology and updates to the taxonomy of the group, researchers are now in a position to explore the drivers of the spectacular radiation of the group, notably in Madagascar, where the highest phenotypic and species diversity occurs.

This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:AAF9F440‐A2D6‐4483‐BF35‐9BC074D9D29B.
Hybrid Englishes: An exploratory survey
Authors: SCHNEIDER EDGAR W.
Published: June 2016

One of the most striking findings when comparing the ecologies of world Englishes is the amount of language mixing and the number of truly mixed (hybrid) varieties involving Englishes. The formula X [language name] + English has produced blends in many different countries, like Taglish, Singlish, Hinglish, Chinglish, Japlish, Denglisch, Finglish, etc. Others include ‘mix‐mix’ in Hong Kong, Sheng in Kenya, or Camfranglais in Cameroon, or lack a commonly accepted designation (in Malaysia, Pakistan, South Africa, and so on). This article offers a systematic but exploratory survey of varieties, linguistic practices and contexts which tend to be viewed in isolation but show similarities in some of their properties and sociolinguistic settings.
English in the international workplace in Russia
Authors: GRITSENKO ELENA , LALETINA ALEXANDRA
Published: June 2016

The study examines language practices in Russian offices of two international companies. We surveyed and interviewed employees about corporate language policies, their rationale of language choice in different contexts, and ideological underpinnings for the use of English in the workplace. Following Blommaert (2010), both offices are theorized as polycentric communicative spaces where English represents the global interactive regime stemming from the global corporate center. The Russian language orients at the local center and embodies the local interactive regime. Language mixing in the form of professional jargon is linked to the workplace efficiency center. It facilitates communication between colleagues and serves as a marker of the Russian professional identity in the English lingua franca workplace.
Endogenous and exogenous control of gastrointestinal epithelial function: building on the legacy of Bayliss and Starling
Authors: Barrett Kim E.
Published: June 2016

Transport of fluid and electrolytes in the intestine allows for appropriate adjustments in luminal fluidity while reclaiming water used in digesting and absorbing a meal, and is closely regulated. This article discusses various endogenous and exogenous mechanisms whereby transport is controlled in the gut, placing these in the context of the ideas about the neurohumoral control of alimentary physiology that were promulgated by William Bayliss and Ernest Starling. The article considers three themes. First, mechanisms that intrinsically regulate chloride secretion, centred on the epidermal growth factor receptor (EGFr), are discussed. These may be important in ensuring that excessive chloride secretion, with the accompanying loss of fluid, is not normally stimulated by intestinal distension as the meal passes through the gastrointestinal tract. Second, mechanisms whereby probiotic microorganisms can impart beneficial effects on the gut are described, with a focus on targets at the level of the epithelium. These findings imply that the commensal microbiota exert important influences on the epithelium in health and disease. Finally, mechanisms that lead to diarrhoea in patients infected with an invasive pathogen, Salmonella, are considered, based on recent studies in a novel mouse model. Diarrhoea is most likely attributable to reduced expression of absorptive transporters and may not require the influx of neutrophils that accompanies infection. Overall, the goal of the article is to highlight the many ways in which critical functions of the intestinal epithelium are regulated under physiological and pathophysiological conditions, and to suggest possible targets for new therapies for digestive disease states.
Analytical Solutions for a Quad-Linear Flow Model Derived for Multistage Fractured Horizontal Wells in Tight Oil Reservoirs
Authors: Wang Wendong , Shahvali Mohammad , Su Yuliang
Published: June 2016

Analysis of microseismic field data shows that the stimulated reservoir volume (SRV) in unconventional reservoirs partially covers the area between hydraulic fracture stages. Consequently, we are often faced with an effective fracture network area (EFNA) rather than a full SRV in such reservoirs. In this paper, we develop a new semi-analytical solution for pressure of hydraulically fractured horizontal wells in tight oil reservoirs with various SRV sizes. Our model is based on four linear flow regions including the hydraulic fracture, the stimulated reservoir, the unstimulated reservoir, and the outer reservoir region. Flow in each region is represented by a set of governing equations and boundary conditions that are coupled to those of other regions. The dual-porosity formulation represents the SRV, while single-porosity formulation is used for other flow regions. We transform the coupled system of equations into Laplace domain, solve for wellbore pressure, and invert the solutions back to time domain numerically. We validate the semi-analytical solutions by comparing them to other semi-analytical solutions in the literature for the special case of trilinear flow. We further validate the quad-linear flow solutions using numerical simulation. Based on the semi-analytical solutions, we generate logarithmic plots of wellbore pressure and pressure derivative. Moreover, we perform sensitivity studies to present the degree to which the solutions vary as size and other properties of the SRV change.
On Railroad Tank Car Puncture Performance: Part I — Considering Metrics
Authors: Jeong David Y. , Perlman Benjamin , Alexy Karl , González Francisco
Published: June 2016

This paper is the first in a two-part series on the puncture performance of railroad tank cars carrying hazardous materials in the event of an accident. Various metrics are often mentioned in the open literature to characterize the structural performance of tank cars under accident loading conditions. One of the consequences in terms of structural damage to the tank during accidents is puncture. This two-part series of papers focuses on four metrics to quantify the performance of tank cars against the threat of puncture: (1) speed, (2) force, (3) energy, and (4) conditional probability of release.

In this paper (Part I), generalized tank car impact scenarios are illustrated. Particular focus is given to the generalized shell impact scenario because performance-based requirements for shell puncture resistance are being considered by the regulatory agencies in United States and Canada. Definitions for the four performance metrics are given. Physical and mathematical relationships among these metrics are outlined. Strengths and limitations of these performance metrics are discussed.

In Part II, the multi-disciplinary approach to develop engineering tools to estimate the performance metrics will be described. The complementary connection between testing and modeling will be emphasized. Puncture performance metrics, which were estimated from other sources, will be compared for different tank car designs. These comparisons will be presented to interpret the metrics from a probabilistic point of view. In addition, sensitivity of the metrics to the operational and design factors will be examined qualitatively.
Modeling Progressive Settlement of a Railway Bridge Transition
Authors: Wilk Stephen T. , Stark Timothy D.
Published: June 2016

This paper illustrates the impact of progressive settlement on a railway bridge transition using a three-dimensional dynamic numerical model that includes the train truck, rails, ties, ballast, subgrade, and bridge abutment and structure. A settlement law that relates tie load to ballast settlement is presented and demonstrated using an iterative fashion to evaluate bridge transition response to 28 MGT. The results illustrate: (1) development of the commonly observed dip about 2.5 to 3.7 m (8 to 12 feet) from the entrance bridge abutment, (2) tie-ballast gaps progressively increase in height and expand to ties outwards from the bridge abutment, (3) a redistribution of load to ties outwards from the bridge abutment as tie-ballast gaps develop and increase, and (4) a ballast surface profile that attempts to minimize tie loads by evenly distributing the wheel load amongst adjacent ties.
Dynamic Wheel-Rail Forces on Mismatched Joints With Ramps
Authors: Marquis Brian , Greif Robert
Published: June 2016

The discontinuity between rail ends at a joint creates dynamic wheel-rail forces (i.e. high impact forces and wheel unloading) that can result in a range of problems including wear, deterioration, and early failure of the track structure, its components, and passing equipment. The response and magnitude of the dynamic wheel-rail forces generated at joints depend upon the form of the discontinuity (e.g. battered rail ends, ramps, gaps, mismatches, etc.) and the support condition. Joints with battered rail ends, which result from degradation due to repeated impact loading, have been extensively analyzed using closed form expressions developed by Jenkins [1] to estimate P1 and P2 impact forces. While appropriate for analyzing joints with battered rail ends, P1 and P2 forces are not directly applicable to other forms of discontinuity at joints such as mismatches in which the rail ends are offset vertically when installed.

Under certain circumstances, railroads are introducing ramps (by grinding or welding) to reduce the mismatch discontinuity and produce a smoother transition in order to mitigate these dynamic wheel-rail forces. In this paper, analyses are conducted to estimate dynamic wheel-rail forces at joints having ramps and mismatches of various sizes using simplified models along with detailed NUCARS models for comparative purposes. The Federal Railroad Administration (FRA) Track Safety Standards (49 CFR Part213) [2] limit the maximum mismatch at joints by Track Class in order to minimize the impact forces which deteriorate the track structure, its components, and equipment, and may ultimately lead to derailment. Parametric studies are conducted to examine the effects of ramp length, direction of travel, mismatch height, and equipment speed (track class). Plots of primary shock-response-spectrum (maximum impact force on the ramp), residual shock-response-spectrum (maximum impact force after the ramp), and minimum wheel force (i.e. wheel unloading) are developed to provide guidelines on ramp length (H-rule) in order to control the maximum force by track class.
Study on Ballast Particle Movement at Different Locations Beneath Crosstie Using “SmartRock”
Authors: Liu Shushu , Huang Hai , Qiu Tong , Gao Yin
Published: June 2016

Ballast compaction and particle rearrangement cause ballast to rotate and move vertically and horizontally. Ballast movement, including translation and rotation, has a significant effect on track performance. Large movement of ballast particles leads to track geometry roughness, e.g., hanging ties, and thus increases potential of damage and deterioration to rails, ties and fastening components. This study investigated ballast particle movement at different locations beneath a crosstie. In the paper, a wireless device — “SmartRock” was utilized to monitor ballast movement under cyclic loading in laboratory tests. The SmartRock has a shape of a realistic ballast particle. Inside the SmartRock was imbedded a tri-axial accelerometer, tri-axial gyroscope, and tri-axial magnetometer with 9 degrees of freedom so that particle translation, rotation and orientation can be interpreted, relatively. The real-time measurements were recorded by the SmartRock and then sent to a computer via Bluetooth. In the laboratory tests, a ballast box was constructed. In the ballast box, a half section of a typical railroad track was constructed. Five hundred cyclic load repetitions were applied on the top of the rail. Translational and rotational accelerations of the particle were recorded by the “SmartRock”. Three ballast box tests were conducted. Two SmartRocks were placed beneath the middle of tie and the edge of tie, respectively but at different depths during each test — right under the tie, 12 cm beneath the tie and 25 cm beneath the tie. The results indicated that (1) ballast particles had translational as well as rotational modes under cyclic loading; (2) ballast particles had rotation together with horizontal translation; (3) particle rotation were higher beneath the edge of tie than those beneath the middle of tie; (4) Ballast movement were significantly reduced with depth. The paper also further confirmed that the SmartRock was capable of recording real-time translational and rotational accelerations, which would not have altered the motions of surrounding ballast particles due to its realistic shape of a particle, hence, provided a new means to monitor ballast particle movement in railroad engineering.
Non-Contact Ultrasonic Guided Wave Inspection of Rails: Next Generation Approach
Authors: Mariani Stefano , Nguyen Thompson V. , Zhu Xuan , Sternini Simone , Lanza di Scalea Francesco , Fateh Mahmood , Wilson Robert
Published: June 2016

The University of California at San Diego (UCSD), under a Federal Railroad Administration (FRA) Office of Research and Development (R&D) grant, is developing a system for high-speed and non-contact rail defect detection. A prototype using an ultrasonic air-coupled guided wave signal generation and air-coupled signal detection, paired with a real-time statistical analysis algorithm, has been realized. This system requires a specialized filtering approach based on electrical impedance matching due to the inherently poor signal-to-noise ratio of air-coupled ultrasonic measurements in rail steel. Various aspects of the prototype have been designed with the aid of numerical analyses. In particular, simulations of ultrasonic guided wave propagation in rails have been performed using a Local Interaction Simulation Approach (LISA) algorithm. The system’s operating parameters were selected based on Receiver Operating Characteristic (ROC) curves, which provide a quantitative manner to evaluate different detection performances based on the trade-off between detection rate and false positive rate. The prototype based on this technology was tested in October 2014 at the Transportation Technology Center (TTC) in Pueblo, Colorado, and again in November 2015 after incorporating changes based on lessons learned.
Introduction to Chemical Stabilization of Unstable Trackbeds
Authors: Tannoury George A. , Schrock Steven D.
Published: June 2016

Trackbeds are typically composed of all granular materials comprised of ballast and subballast over compacted subgrade. Most poor performances of railroads can be attributed to poor and unstable subgrade conditions. Below the surface, the instability of the subgrade material can propagate through the granular zone leading to excessive settlements and deformations of the railway. Conventional subgrade restoration in the trackbed system requires the removal of the granular materials and over-excavation of soft unstable subgrade materials, moisture adjustment, re-compaction, and sometimes chemical stabilization of the subgrade soils. Since these procedures are considered very expensive in terms of construction equipment, railway outage time, and labor force, alternative solutions for consideration and evaluation are essential.

Injection of expansive foam (polymer based) materials is a relatively recent method that has been used in various applications of soil stabilization in the roadway industry. This technique relies on the injection of rigid-polyurethane foam, which is a high-density, expanding, thermoset, hydro-insensitive and environmentally neutral polyurethane-resin product, into the soft and unstable soil to improve their shear strength and stability index. In addition, the stabilized zone acts as a waterproof membrane protecting moisture sensitive subgrade, and acting as a separation layer to eliminate pumping and contamination of the granular subballast at saturated fine grained conditions.

The objective of this paper is to evaluate the practicability of polyurethane stabilized soft and unstable subgrade under unbounded granular trackbeds to mitigate future deformation, restore railway foundation, and reduce trackbed repair cost and outage time.
Advancing Pedestrian Safety and Case Study of Pedestrian Psychology at Railroad Grade Crossing
Authors: Shehada Mohammad , Ahuja Akshit , Schrock Steven D.
Published: June 2016

Contrary to the declining railroad-highway crossing crashes over the past decade, the pedestrian-railroad interface has remained relatively unchanged. While engineering solutions and law enforcement have been tried, little is known about their effectiveness on the pedestrian mindset and psychology.

One of the main reason for crashes of this type is that pedestrians tend to be restless while waiting at railroad crossings. This can lead to pedestrians performing irrational acts such as attempting to walk across a crossing before a train arrives. Earlier, trains traveled at slower speeds which pedestrians could react to easily and trains had less freight so it needed less braking distance and thus it was easier to control them. There are many factors with the potential to improve pedestrian safety at railroad crossings.

In this paper the current safety norms for railroad crossings existing across in more than 40 major cities in US were analyzed to determine the existing safety standards for pedestrians at railroad grade crossings. State departments of transportation (DOTs) were contacted, along with professionals in public and private sector involved in safety at railroad crossing and ask them what according to them is a high risk railroad grade crossings in their area, safety practices that are common in their area, various threats to Safety implementation and then analyze these crossing for the types, safety signs and equipment present at them.
Comparison of Transfer Lengths in Pretensioned Concrete Railroad Ties Subjected to Different Magnitudes of Rail Loads
Authors: Bodapati Naga Narendra B. , Peterman Robert J. , Beck B. Terry , Wu Chih-Hang John
Published: June 2016

In order to quantify the effect of different reinforcement types on transfer lengths, an extensive study was conducted with the selected group of twelve different reinforcement types. These reinforcements are extensively used to produce concrete railroad ties across the world. These employed twelve (12) different types are of 5.32 mm diameter wires with different surface indent geometries. A research team from Kansas state university visited a PCI certified concrete tie manufacturing plant during January 2013. During the plant visit, four (4) concrete railroad ties were cast for each reinforcement type for a total of 48 ties. Considerable part of the study conducted at the plant was previously published by the authors. However for effective understanding, brief explanation of the tie manufacturing process will be presented in this paper. Strain measuring points were mounted on the bottom surface of a concrete railroad tie during the casting process. Proper measures were taken to safeguard these strain measuring points during loading. Transfer lengths were calculated using these mounted strain measuring points. Transfer length measurements were calculated at the plant, immediately after the application of prestressing forces to the concrete ties. After the casting process, two ties for each reinforcement type were stored at plant location for approximately one year and the remaining two ties (companion ties) for the each reinforcement types were shipped and stored at Kansas state university. Transfer length measurements were again calculated at this stage for all 48 ties. Ties stored at plant location were later subjected to cumulative in-track railroad loading of 85 million gross tons over six (6) months period of time. Whereas, the companion ties stored at Kansas state university were not subjected to any loading. Transfer lengths are calculated and compared at this stage and presented [4] in the past.

Ties which were already subjected to 85 million gross tons were further loaded to cumulative total of 236.3 million gross tons and the companion ties stored at Kansas State University were not subjected to any loading. Transfer lengths for the ties (twenty four) that were subjected 263.3 million gross tons were calculated and presented in this paper with detailed explanation. Transfer length behavior under different magnitudes of loading is also presented along with the discussion.
High Speed Rail Short Bridge-Track-Train Interaction Based on the Decoupled Equations of Motion in the Finite Element Domain
Authors: Nour Said I. , Issa Mohsen A.
Published: June 2016

The interaction between the train, track, and bridge was considered as an interaction between two decoupled subsystems. A first subsystem consisted of the train vehicle simulated as a four-wheelset mass-spring-damper system having two layers of suspensions and ten degrees of freedom. A second subsystem consisted of the track-bridge system assumed to be a top rail beam and a bottom bridge beam coupled by continuous springs and dampers representing the elastic properties of the trackbed smeared over the spacing of the railway ties. The bridge supports were assumed to be rigid or flexible. The equations of motion of a finite element form were derived for each subsystem independently by means of the Newton’s second law. The dynamic interaction between the moving vehicle of the first subsystem and the stationary underlying track-bridge structure of the second subsystem was established by means of a no-separation constraint equation in the contact points between the wheels and the rails. The proposed two-dimensional analysis was intended to accurately describe the vertical behavior of short span bridges subjected to high-frequency excitations due to the passage of high speed trains; therefore, shear deformations, rotational inertia effects, and consistent mass matrices were adopted in the mathematical model. Numerical solutions of the decoupled equations of motion for both subsystems were obtained with the step-by-step direct integration in the time domain using HHT alpha method with a special scheme in the contact interface. The solution accuracy of the proposed method was validated against responses obtained from a semi-analytical method of a train car travelling over a simply supported bridge. The practical engineering application was demonstrated with a case study investigating effects of key parameters in the behavior of a ballasted short span railway bridge. Compared with the moving force model, results showed that for bridges with rigid supports both the vehicle interaction and trackbed produce lower peak responses at resonance speeds with the latter being more significant. However an increase in support flexibility had a greater impact across all speeds in increasing the bridge responses.
Effect of Design Rail Cant on Concrete Crosstie Rail Seat Pressure Distribution
Authors: Ghosh Arkaprabha , Edwards J. Riley , Dersch Marcus S.
Published: June 2016

Previous research has focused on the effect of rail cant on rail wear and wheel/rail interaction, indicating that a steeper rail cant results in increased wear on rails and wheels. However, no research has investigated the effect of rail cant on the crosstie rail seat pressure distribution. Past research at the University of Illinois at Urbana-Champaign (UIUC) looked into the effect of negative (reverse) rail cant on pressure distribution across the rail seat utilizing matrix-based tactile surface sensors (MBTSS) on artificially created rail seat wear profile at TTC, Pueblo. These results showed that the pressure distribution became more non uniform with increasing negative rail cant. This paper looks into the effect of ‘design’ rail cant on pressure distribution across the rail seat. Static tests were carried out on 1:30 and 1:40 cant crossties imparting a predefined sequence of vertical and lateral load combinations. MBTSS and potentiometers were used to measure pressure distribution and rail rotation respectively. The 1:30 cant distributed load more evenly than 1:40 cant at lateral to vertical force ratios greater than 0.4. The two rail cants did not show significant differences in the values of average pressure, contact area, or rail rotation.
Flexural Performance of Ultra-High Performance Concrete Ballastless Track Slabs
Authors: Meng Weina , Khayat Kamal Henri
Published: June 2016

Ballastless track slab offers excellent stability and durability and has been well accepted in high-speed railways worldwide. Rails are typically laid on precast concrete slabs that are subjected to dynamic load transferred from the rails. Cracks can be induced by shrinkage and mechanical loading in concrete, which accelerates the degradation and affects the performance of the track slab. As tens of thousands of miles of ballastless track are constructed, effective and efficient maintenance for the concrete slabs has become an issue. In this paper, ultra-high performance concrete (UHPC) is proposed to fabricate ballastless track slab. UHPC is a superior fiber-reinforced, cementitioius mortar, which has greatly-improved mechanical strengths and durability. A recently-developed UHPC is evaluated in terms of the flowability, durability, shrinkage, and mechanical properties. A functionally-graded slab design is proposed with the consideration of initial material cost. The slab is cast with two layers: a layer of conventional concrete at the bottom, and a layer of UHPC on the top. A three-dimensional finite element model is developed for ballastless track slab whose flexural performance is investigated and compared with that of slab made with conventional concrete. Concrete damage plasticity model is incorporated to consider the post-cracking behavior. The results indicate that the proposed UHPC is promising for fabricating ballastless track slab with superior performance.
Temperature Profiles of Railroad Tapered Roller Bearings With Defective Inner and Outer Rings
Authors: Tarawneh Constantine M. , Sotelo Luz , Villarreal Anthony A. , de los Santos Nancy , Lechtenberg Ryan L. , Jones Robert
Published: June 2016

In the railroad industry, monitoring the condition of key components such as bearings and wheels is vital to ensure the safe transport of goods and commodities. Bearing seizures are amongst the most dangerous types of failures experienced by trains because they occur unexpectedly and may lead to costly derailments. Current bearing health monitoring techniques include tracking the temperature and acoustic emissions given by the bearings. Although temperature histories of railroad tapered roller bearings are readily available, the literature does not provide information relating the temperature profiles to the severity of the bearing defect. The study presented here investigates the correlation between temperature profiles and bearing defect severity measured by the size of spalls present on bearing outer (cup) and inner (cone) rings. The temperature data used for this study was acquired from defective and healthy bearings that were run at various operating load and speed conditions. The data presented here provides the railroad industry with a greater understanding of the thermal behavior of defective bearings, which can be used to assess the future needs of bearing condition monitoring systems.
On the Application of Laser Technology for Top of the Rail Lubricity Detection
Authors: Hasan Abdullah Mohammed , Taheri Andani Masood , Ahmadian Mehdi
Published: June 2016

The application of Laser technology for the top of the rail (TOR) lubricity detection is investigated. A laser-based sensor technology is proposed to detect, measure, and monitor the condition of the TOR lubricants. The optimum configuration of the laser sensor, suitable for effective lubricity measurements, is presented. In the proposed embodiment, the laser head is employed with its beam reflected off of the rail surface. Specular reflection of a lubricated rail is measured and compared with dry condition. A processing technique is developed based on the recorded reflection intensity dissimilarities to identify rail’s lubricity condition. A lubricated rail yields lower reflectivity value, as compared with a dry rail. The TOR detection system is mounted on a hand-operated cart for field testing. The field test results indicate that the proposed technique can successfully assess to what extent TOR lubricants are present on the rail, therefore serve to distinguish between various states of rail lubricity, from completely dry to completely saturated.
Heat Generation in the Railroad Bearing Thermoplastic Elastomer Suspension Element
Authors: Rodriguez Oscar O. , Carbone Juan , Fuentes Arturo A. , Jones Robert E. , Tarawneh Constantine
Published: June 2016

The main purpose of this ongoing study is to investigate the effect of heat generation within a railroad thermoplastic elastomer suspension element on the thermal behavior of the railroad bearing assembly. Specifically, the purpose of this project is to quantify the heat generated by cyclic loading of the elastomer suspension element as a function of load amplitude, loading frequency, and operating temperature. The contribution of the elastomer pad to the system energy balance is modeled using data from dynamic mechanical analysis (DMA) of the specific materials in use for that part. DMA is a technique that is commonly used to characterize material properties as a function of temperature, time, frequency, stress, atmosphere or a combination of these parameters. DMA tests were run on samples of pad material prepared by three different processes: injection molded coupons, transfer molded coupons, and parts machined from an actual pad. The results provided a full characterization of the elastic deformation (Energy Storage) and viscous dissipation (Energy Dissipation) behavior of the material as a function of loading frequency, and temperature. These results show that the commonly used thermoplastic elastomer does generate heat under cyclic loading, though the frequency which produces peak heat output is outside the range of common loading frequency in rail service. These results can be combined with a stress analysis and service load measurements to estimate internally generated heat and, thus, enable a refined model for the evolution of bearing temperature during operation.
Getting Active With Passive Crossings: Investigating the Use of In-Vehicle Auditory Alerts for Highway-Rail Grade Crossings
Authors: Landry S. , Jeon M. , Lautala P. , Nelson D.
Published: June 2016

This paper investigates the plausibility of a novel in-vehicle auditory alert system to warn drivers of the presence of railroad crossings. Train-Vehicle collisions at highway-rail grade crossings continue to be a major issue despite improvements over the past several decades. In 2014 there were 2,286 highway-rail incidents leading to 852 injuries and 269 fatalities. This marked the first time in the past decade that incident rates increased from the previous year. To prevent the overall trend in safety improvement from plateauing, interest is shifting towards novel warning devices that can be applied to all crossings at minimal cost. These novel warnings are intended to complement but not replace the primary visual warnings that are already in place at both active and passive crossings. Few in-vehicle warning systems have been described and tested in the rail safety literature. The ones that have been described only manipulate the modality or reliability of the warning message, and pay little attention to message content, timing of presentation, mappings between crossing events and warning logic, and driver habituation associated with long term use. To this end, a line of research has been being carried out to design in-vehicle auditory alerts and measure subjective preference and driver behavior in response to in-vehicle auditory alerts. The first study included a subjective evaluation of potential auditory cues. Cues rated as most effective and appropriate were included in the design of prototype systems in the follow up study. The second study will measure compliance rates in a driving simulator with and without in-vehicle auditory alerts. The results of first study and the study design for the second study are discussed.
Evaluation of Risk Reduction From Tank Car Design and Operations Improvements: An Extended Study
Authors: Gonzalez Francisco , Prabhakaran Anand , Booth Graydon F. , Gantoi Florentina M.
Published: June 2016

Critical derailment incidents associated with crude oil and ethanol transport have led to a renewed focus on improving the performance of tank cars against the potential for puncture under derailment conditions. Proposed strategies for improving puncture performance have included design changes to tank cars as well as operational considerations, such as reduced speeds and upgraded brake systems. In a prior paper on this topic, the authors conceptualized a novel and objective methodology for quantifying and characterizing the reductions in risk that result from changes to tank car design or to the tank car operating environment.

This paper describes an extension of that effort to include additional derailment cases, additional operating speeds, considerations for alternate train configurations, such as Distributed Power (DP) and Electrically Controlled Pneumatic (ECP) brakes, as well as options for component level studies. In essence, the developed methodology considers key elements that are relevant to tank car derailment performance and combines these elements into a consistent probabilistic framework to estimate the relative merit of proposed mitigation strategies. The relevant elements considered include variations in the derailment scenarios, chaotic derailment dynamics, the distribution of impact loads and impactor sizes, various operating speeds, brake system differences, and variations in tank car design. The paper also provides an overview of the validation efforts which suggest that the gross dynamics of a tank car train derailment, and the resulting puncture performance of the tank cars, are captured well by this methodology.
Predicting the Natural Frequency of Train Structures Using Detailed Finite Element Models
Authors: MacNeill Robert A. , Gough Glenn
Published: June 2016

Train carbody and truck structures are designed to exhibit primary natural frequency modes great enough to avoid unwanted resonant oscillations with normal track interactions. Critical bounce modes can be excited by typical track in the 2–4 Hz range. Trains are designed with first modes above this threshold. Historically, simplified approaches are employed to predict natural frequencies of the main truck and carbody train structures independently. Since the advent of high powered computing, more detailed finite element analysis (FEA) eigenvalue approaches have been used to more accurately predict natural frequency of structures. Still, the typical FEA approach uses simplified boundary conditions and partial models to determine natural frequencies of individual components, neglecting the interaction with other connected structures. In this paper, a detailed, holistic approach is presented for an entire Light Rail Vehicle (LRV). The analysis is performed on a fully detailed FEA model of the LRV, including trucks and suspension, carbody structures, non-structural mass, articulation, as well as intercar and truck-carbody connections. The model was developed for detailed crashworthiness investigations, which requires a high level of fidelity compared to what is typically required for static and modal analysis. Using the same model for multiple purposes speeds up development while also improving the accuracy of the analyses. In this paper, the modal analysis methodology developed is described. A case study is presented investigating the often neglected contribution of windows, cladding, and flooring on the overall carbody natural frequency.
Toward Integrated Life Cycle Assessment and Life Cycle Cost Analysis for Road and Multimodal Transportation Alternatives: A Case Study of the Highland Copper Project
Authors: Kalluri Sumanth , Lautala Pasi , Handler Robert
Published: June 2016

Freight transportation of goods and commodities is a necessity and is often a significant portion of the overall investment in industrial development, especially in the natural resource industry. The economic costs of developing infrastructure have long been factored into the project costs, but environmental or social impacts have received less attention. In addition, alternative transportation modes are rarely compared from both economic and environmental perspectives. This paper performs a Life Cycle Assessment (LCA) for truck-only, multimodal and rail transportation options to transport ore and concentrate. In this paper, LCA is performed in SimaPro for construction/manufacturing, operations, maintenance, and end of life phases to obtain the overall Global Warming Potential (GWP) in terms of kilogram equivalents of CO2 (kg CO2eq). After emissions from alternative options have been defined, the cost of each option can be investigated through Life Cycle Cost Analysis (LCCA) This paper also discusses the past work on LCCA and its application to transportation projects. The final part provides a methodology to convert the emission results from LCA for integration with the costs from LCCA.
Digital Image Correlation Techniques for Prestressed Concrete Tie Quality Control
Authors: Bartelmo Sally , Rajan Sreehari , Li Ning , Sutton Michael , Rizos Dimitrios C.
Published: June 2016

Qualification of prestressed concrete railroad ties is currently performed through testing at the design level following established AREMA guidelines, while important parameters, such as the strand transfer length, are typically not identified. Conventional testing practices are time demanding, expensive and labor intensive. Consequently, implementation of highly reliable, yet cost effective, quality control procedures at the tie production stage is highly appropriate and desired.

In this work, the authors developed a stereo-vision system for both laboratory and industrial environments to measure the 3-D strain fields on the surfaces of prestressed concrete railroad ties. The proposed measurement system is based on the Digital Image Correlation (DIC) techniques developed in University of South Carolina (USC) laboratories over the past three decades. It is a non-destructive, non-contacting technique that has been successfully applied to obtain full-field measurements for a wide range of materials, loading types and temperature conditions. Known as 3D-DIC or Stereo-DIC, the method employs a stereo-vision system to successfully perform quality assessment of concrete ties in relation to the determination of: (i) the transfer length in both laboratory and production facility environments and (ii) full strain fields during product qualification tests to identify product defects. The proposed procedure is introduced and verified through application in a laboratory environment. The implementation of the method is presented and the cost effectiveness, accuracy, and versatility are discussed.