Malone J.,Transportation Technology Center Inc. |
Wickert M.A.,University of Colorado at Colorado Springs
2011 Digital Signal Processing and Signal Processing Education Meeting, DSP/SPE 2011 - Proceedings | Year: 2011
In this paper we consider the performance of Volterra filters in canceling the severe nonlinear amplitude and phase distortions caused by traveling wave tube (TWT) high power amplifiers (HPAs, TWTAs) typically used on many legacy satellite communication systems. The nonlinear nature of Volterra filters would seem to make them a natural choice for canceling intersymbol interference (ISI) resulting from these distortions. Preliminary results of simulation studies using QPSK with up to 5th-order adaptive Volterra kernels filter are presented. The practical aspect of this work is that we would like to achieve good performance while reducing computational complexity, ultimately making efficient implementation on an FPGA feasible. It was found that an LMS adaptive Volterra filter offered significant ISI reduction only at relatively high SNRs (25 dB), while at lower (and more typical) SNRs, improvement was only marginal, as noise tended to dominate the LMS algorithm. Adding a 5th-order Volterra kernel to the linear and 3rd-order LMS kernels offered negligible improvement in performance over the linear and 3rd-order kernels alone. © 2011 IEEE.
Jones K.,Transportation Technology Center Inc.
American Society of Mechanical Engineers, Rail Transportation Division (Publication) RTD | Year: 2013
Component failure in bolsters and side frames remains a problem for both railroads and suppliers, causing expensive repairs and even derailments. To understand and combat this problem, an evaluation of the steel was required. Bolsters were obtained from several suppliers to evaluate the current state of Association of American Railroads (AAR) M-201 standard for Grade B+ cast steel. Charpy impact and tensile test samples were machined from critical areas of these castings and tested at an independent laboratory. Distinct differences were found in processes and in mechanical properties between some suppliers. Supplier names are not identified in this paper. Based on the chemical and mechanical testing results and data analysis, changes to AAR M-201 Grade B+ requirements have been proposed. Additional bolsters have been obtained for further testing. These bolsters will incorporate the proposed changes to the standard and the same mechanical testing will be performed on them to determine the effectiveness of the proposed changes. Full scale static or fatigue testing will be conducted on additional bolsters. A survey of scrapped bolsters and side frames from several railcar producers and reclaim operations was conducted to determine the leading causes of failures of components removed from service. These results form the basis for a database that can be used to identify failure trends. Copyright © 2013 by ASME.
Ordonez Olivares R.,University of Pittsburgh |
Garcia C.I.,University of Pittsburgh |
DeArdo A.,University of Pittsburgh |
Kalay S.,Transportation Technology Center Inc. |
And 2 more authors.
Wear | Year: 2011
Rail is the most valuable asset owned by railroads the AAR reported that only in North America the annual expenditure for rail repair and replacement is approximately $2.6 billion. In the last 50 years the railways and rail manufacturers have improved rail performance. Modern rail metallurgies have achieved a successful increased in hardness from 248 Hardness Brinell (HB) to more than 400. HB. This in turn increased the wear resistance of rails and a life extension. Lubrication and suspension bogies have positively contributed to rail life extension as well. Unfortunately, not as much progress has been made as far as rail's fatigue performance (e.g. rolling contact fatigue (RCF)), and fracture toughness. In this work is presented a methodology followed to development a new metallurgy that will increase RCF and wear resistance. The development of this new rail consists of rail characterization and advanced rail steel design. © 2010.
Wu H.,Transportation Technology Center Inc |
Wilson N.,Transportation Technology Center Inc
The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015 | Year: 2016
Four application scenarios using one type of a top of rail friction modifier (TORFM) during track testing and in NUCARS® modeling simulations1 were performed to study the effects of wheel-rail forces. Results indicated controlled TORFM application can considerably reduce lateral forces, resulting in reduced risk of rail rollover, lower levels of rail wear, and lower risk of rolling contact fatigue. However, failed TORFM application on the low rail in curves, such as that caused by a broken hose or clogged ports, can cause considerably higher lateral forces. A TORFM applied to only the low rail in curves can result in lower lateral forces similar to TORFMs applied on both rails. Modeling analysis indicated that the percentage Kalker factors and wheel-rail profile combinations involved in the simulations can have considerable effects on the simulation results of lateral forces. © 2016 Taylor & Francis Group, London.
Transportation Technology Center Inc. | Date: 2010-02-02
Railroad rail steels having a pearlitic structure and containing 0.720 to 0.860 wt % carbon; 1.000 to 1.280 wt % manganese; 0.450 to 1.000 wt % silicon; 0.010 to 0.100 wt % copper; 0.150 to 0.280 wt % chromium; 0.0010 to 0.0500 wt % aluminum; 0.050 to 0.120 wt % nickel; 0.100 to 0.260 wt % molybdenum; 0.100 to 0.210 wt % vanadium; 0.0010 to 0.0065 wt % nitrogen; 0.0010 to 0.0080 wt % phosphorus; 0.0010 to 0.0040 wt % sulfur; and 0.0100 to 0.0350 wt % niobium with the remainder of said steel being iron, can be used to make railway rails that are particularly resistant to rolling contact fatigue and, hence, shelling.
Transportation Technology Center Inc. | Date: 2013-04-24
A method is provided for detecting broken rail, unintentionally misaligned turnouts, and track occupancy ahead of or behind a railway vehicle traveling on a railroad track. Shunts extend between the rails at intervals along the railroad track. Each shunt has electrical signal transmission characteristics differing from those of adjacent shunts. A test unit on the railway vehicle induces a test signal in a first rail to create a track circuit in which the test signal propagates along the first rail, through at least one of the shunts, returns to the railway vehicle along the second rail, and through the wheels and axle of the railway vehicle. The test signal has electrical properties selected to interact with at least one of the shunts. The received test signal on the second rail is analyzed to identify predetermined conditions concerning the status of the railroad track.
Transportation Technology Center Inc. | Date: 2016-04-14
A system for inspecting railroad rail using phased array ultrasonic technology includes both high-speed and high-resolution inspection modes that obviate the need for an operator to dismount the truck to perform detail inspection. In high-speed inspection mode, the phased array probes operate at fixed angles with respect to the rail to identify potential rail defects as the vehicle moves along the track. The vehicle can then return to the location of a potential rail defect and switch to a high-resolution inspection mode in which the phased array probes sweep over a range of beam angles at the location of a potential rail defect.
Transportation Technology Center Inc. | Date: 2016-04-14
A system for inspecting railroad rail using phased array ultrasonic technology measures the time of flight of ultrasonic signals at locations across the rail head to determine the wear profile of the rail. The rail wear profile is then used to adjust the focal laws of the phased array ultrasonic probes to dynamically compensate for changes in the rail profile as the inspection vehicle moves along the rails.
Transportation Technology Center Inc. | Date: 2013-06-13
A method is provided for detecting broken rail, track continuity, and track occupancy ahead of or behind a railroad vehicle traveling in fixed-block territory equipped with an AC track code wayside signal system or cab signal overlay system, and a communications link. This method, when used as an integral part of a communications-based train control (CBTC) or positive train control (PTC) system, allows immediate, automatic detection of broken rail, track occupancies, or open turnouts ahead of or behind a train in an occupied block. It also facilitates true moving-block or virtual block CBTC or PTC, thereby enabling higher efficiency and track utilization.
Transportation Technology Center Inc. | Date: 2016-12-13
garment bags for travel, briefcases. mugs, cups. hats, caps, t-shirts, polo shirts, sweaters, sweatshirts. educational services, namely providing response training courses in the fields of hazardous materials and emergency responses.