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Broadway, MA, United States

Sussmann T.R.,Volpe Center | Ruel M.,Canadian National Railway | Chrismer S.M.,AMTRAK
Transportation Research Record | Year: 2012

Railway ballast is a critical element in the railway track support structure. The ballast is often overlooked when inspection tools are developed for track. When ballast is not functioning correctly, the strength of the track structure may be inadequate and thus compromise track stability. Track stability-related failures vary from rapid deterioration with little warning to slow and progressive deterioration with often predictable required maintenance. Ballast-related deterioration is progressive and usually provides visual evidence to warn maintenance personnel of needed rehabilitation. However, the blocked drainage that develops with fouled ballast can result in a saturated roadbed that is not stable and could rapidly deteriorate to an unsafe condition with little warning. Although massive failures are rare, if a side hill fill or embankment deteriorates to the point of becoming susceptible to massive failure, then the challenge becomes evaluation. More detailed knowledge of the track support condition will be needed for a thorough evaluation than can be provided by current track inspections, except for costly detailed visual inspections. The current standard of practice for ballast inspection and maintenance can be improved to reduce the risk of sudden failure. Much of the required technology, knowledge, and resources is already available and being utilized under the current system. A more precise evaluation of ballast condition is essential to identify thresholds related to unsafe track support conditions and to support effective maintenance plans. Source


Cooper C.,Volpe Center | Reinhart T.,Southwest Research Institute
SAE International Journal of Commercial Vehicles | Year: 2015

This paper presents the results of engine and vehicle simulation modeling for a wide variety of individual technologies and technology packages applied to two medium-duty vocational vehicles. Simulation modeling was first conducted on one diesel and two gasoline medium-duty engines. Engine technologies were then applied to the baseline engines. The resulting fuel consumption maps were run over a range of vehicle duty cycles and payloads in the vehicle simulation model. Results were reported for both individual engine technologies and combinations or packages of technologies. Two vehicles, a Kenworth T270 box delivery truck and a Ford F-650 tow truck were evaluated. Once the baseline vehicle models were developed, vehicle technologies were added. As with the medium-duty engines, vehicle simulation results were reported for both individual technologies and for combinations. Vehicle technologies were evaluated only with the baseline 2019 diesel medium-duty engine. The vehicle technology combinations in the T270 delivery truck yielded from 1% to 12% fuel savings, averaged over all the duty cycles. Fuel savings for the diesel engine technology packages ranged from 1% to 5%, averaged over all the duty cycles. The simulation of gasoline engine technology packages produced from 6% to 9% and 6% to 10% for the V-6 and V-8 engines, respectively. The benefits of individual technologies vary widely depending on the drive cycles. Copyright © 2015 SAE International. Source


Badain N.,Southwest Research Institute | Reinhart T.,Southwest Research Institute | Cooper C.,Volpe Center
SAE International Journal of Commercial Vehicles | Year: 2015

This paper presents the fuel consumption results of engine and vehicle simulation modeling for a wide variety of individual technologies and technology packages applied to a long haul heavy duty vehicle. Based on the simulation modeling, up to 11% in fuel savings is possible using commercially available and emerging technologies applied to a 15L DD15 engine alone. The predicted fuel savings are up to 17% in a Kenworth T700 tractor-trailer unit equipped with a range of vehicle technologies, but using the baseline DD15 diesel engine. A combination of the most aggressive engine and vehicle technologies can provide savings of up to 29%, averaged over a range of drive cycles. Over 30% fuel savings were found with the most aggressive combination on a simulated long haul duty cycle. Note that not all of these technologies may prove to be cost-effective. The fuel savings benefits for individual technologies vary widely depending on the drive cycles and payload. Copyright © 2015 SAE International. Source


Reinhart T.,Southwest Research Institute | Cooper C.,Volpe Center
SAE International Journal of Commercial Vehicles | Year: 2015

Medium- and Heavy Duty Truck fuel consumption and the resulting greenhouse gas (GHG) emissions are significant contributors to overall U.S. GHG emissions. Forecasts of medium- and heavy-duty vehicle activity and fuel use predict increased use of freight transport will result in greatly increased GHG emissions in the coming decades. As a result, the National Highway Traffic Administration (NHTSA) and the United States Environmental Protection Agency (EPA) finalized a regulation requiring reductions in medium and heavy truck fuel consumption and GHGs beginning in 2014. The agencies are now proposing new regulations that will extend into the next decade, requiring additional fuel consumption and GHG emissions reductions. To support the development of future regulations, a research project was sponsored by NHTSA to look at technologies that could be used for compliance with future regulations. Data presented in this paper detail how engine and vehicle simulation models were developed for current medium and heavy duty vehicles and then validated against available test results. In addition, the paper describes how potential future engine and vehicle technologies were added to the baseline models to simulate future improvements in medium and heavy duty vehicle fuel consumption and GHG emissions. Wherever possible, experimental data was used as inputs to the models or to validate the simulation results. The effect of drive cycle on engine efficiency is also explored. . Source


Reeves A.,Northeastern University | Grayhem R.,Northeastern University | Grayhem R.,Volpe Center
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2016

Rod-mediated 500 nm test spots were flashed in Maxwellian view at 5 deg eccentricity, both on steady 10.4 deg fields of intensities (I) from 0.00001 to 1.0 scotopic troland (sc td) and from 0.2 s to 1 s after extinguishing the field. On dim fields, thresholds of tiny (50) tests were proportional to √I (Rose-DeVries law), while thresholds after extinction fell within 0.6 s to the fully dark-adapted absolute threshold. Thresholds of large (1.3 deg) tests were proportional to I (Weber law) and extinction thresholds, to √I. Conclusions: rod thresholds are elevated by photon-driven noise from dim fields that disappears at field extinction; large spot thresholds are additionally elevated by neural light adaptation proportional to √I. At night, recovery from dimly lit fields is fast, not slow. © 2016 Optical Society of America. Source

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