scholarly journals Development of a Passenger Wheel Standard

2005 ◽  
Author(s):  
Jeff Gordon ◽  
Daniel H. Stone
Keyword(s):  
Thermal Damage ◽  
Public Transit ◽  
Fatigue Cracking ◽  
Operating Conditions ◽  
Normal Operating ◽  
Design Standard ◽  
Service Environment ◽  
Service Conditions ◽  
Transit Agencies ◽  
Original Equipment Manufacturers

The American Public Transit Association (APTA) is seeking to develop specifications to ensure that wheels used in passenger applications perform safely under the service conditions to which they are exposed. To this end, an approach has been developed which will address this need at two levels. First, a variant on the Association of American Railroads (AAR) S-660 standard [1] is proposed with loading requirements that more realistically represent typical conditions in passenger operations. This is considered a design standard and is to be applied to identify wheel designs not susceptible to fatigue cracking in the wheel plate and hub suitable for use by transit and commuter agencies. Second, an application standard (or more precisely, a recommended practice) has been conceived which is designed to assist transit agencies (or original equipment manufacturers) in the appropriate choice of an “approved” wheel design based on the expected service environment. This technique will identify wheel designs which, under normal operating conditions, should not result in thermal damage to the wheel tread.

The Abrasion Question. Some Factors in the Deterioration of Rubber When Exposed to Frictional Contacts with Other Materials

1933 ◽  
Vol 6 (3) ◽  
pp. 345-350
Author(s):  
V. A. Cosler
Keyword(s):  
Operating Conditions ◽  
Frictional Contacts ◽  
Normal Operating ◽  
The Road ◽  
Fundamental Factor ◽  
Actual Service ◽  
Modifying Effect ◽  
Service Conditions ◽  
Fundamental Value ◽  
Open Question

Abstract If we accept the proposal that the fundamental effect produced by the machines diagrammed in Fig. 1 is that of dragging a series of saw-toothed paddles across the surface of rubber specimens, we must accept as fact the theorem that the results recorded by these types of machines is a summarization of values rather than a fundamental value. If we accept the evidence that relations cannot be varied on any type of present abrasion testers to duplicate the conditions existing in all situations where rubber is exposed to frictional contacts with other materials, we must accept the fact that some fundamental factor is absent, or is over- or under-emphasized as these relations are varied. Whether these missing reactions can be supplied by evaluating other characteristics which will properly modify the results obtained on any given abrasion tester is an open question. It can be safely stated, however, that results obtained from any type of tester discussed can only be considered as evaluating rubber compositions at or near the point of optimum cure under one particular set of wear conditions. With one exception these conditions may safely be considered as approximating the conditions obtaining between a tire tread and the road under normal operating conditions. The Sproul-Evans tester may safely be considered as more closely approximating sand-blast hose conditions than tire-road conditions. It is the thought of the author that the most promising field of future endeavor lies in the direction of studying the possibility of reproducing more fundamental effects, rather than attempting to add more reactions to the already complex set of conditions present in the known types of abrasion testers. The suggestion is also offered that a most promising field of study lies in the direction of studying the modifying effect of distortion upon the fundamental characteristics of rubber, and attempting to establish the extent of distortion present when rubber is exposed to frictional disintegration in actual service conditions.

scholarly journals Structural assessment of the EU-DEMO WCLL Central Outboard Blanket segment under normal and off-normal operating conditions

2021 ◽  
Vol 167 ◽  
pp. 112350
Author(s):  
Ilenia Catanzaro ◽  
Pietro Arena ◽  
Salvatore Basile ◽  
Gaetano Bongiovì ◽  
Pierluigi Chiovaro ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Structural Assessment ◽  
Normal Operating ◽  
The Eu

Analysis of Pellet-to-Cladding Gap Closure for a Metallic Micro-cell Pellet under Normal Operating Conditions

2021 ◽  
pp. 153186
Author(s):  
Yang-Hyun Koo ◽  
Jae-Ho Yang ◽  
Dong-Seok Kim ◽  
Dong-Joo Kim ◽  
Chang-Hwan Shin ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Normal Operating ◽  
Gap Closure ◽  
Cell Pellet

Transit Planning Optimization Under Ride-Hailing Competition and Traffic Congestion

2021 ◽  
Author(s):  
Keji Wei ◽  
Vikrant Vaze ◽  
Alexandre Jacquillat
Keyword(s):  
New York ◽  
Traffic Congestion ◽  
Service Providers ◽  
Public Transit ◽  
Mixed Integer ◽  
Nonlinear Program ◽  
Transit Planning ◽  
Planning Optimization ◽  
Transit Ridership ◽  
Transit Agencies

With the soaring popularity of ride-hailing, the interdependence between transit ridership, ride-hailing ridership, and urban congestion motivates the following question: can public transit and ride-hailing coexist and thrive in a way that enhances the urban transportation ecosystem as a whole? To answer this question, we develop a mathematical and computational framework that optimizes transit schedules while explicitly accounting for their impacts on road congestion and passengers’ mode choice between transit and ride-hailing. The problem is formulated as a mixed integer nonlinear program and solved using a bilevel decomposition algorithm. Based on computational case study experiments in New York City, our optimized transit schedules consistently lead to 0.4%–3% system-wide cost reduction. This amounts to rush-hour savings of millions of dollars per day while simultaneously reducing the costs to passengers and transportation service providers. These benefits are driven by a better alignment of available transportation options with passengers’ preferences—by redistributing public transit resources to where they provide the strongest societal benefits. These results are robust to underlying assumptions about passenger demand, transit level of service, the dynamics of ride-hailing operations, and transit fare structures. Ultimately, by explicitly accounting for ride-hailing competition, passenger preferences, and traffic congestion, transit agencies can develop schedules that lower costs for passengers, operators, and the system as a whole: a rare win–win–win outcome.

On-Demand Public Transit: A Markovian Continuous Approximation Model

2021 ◽  
Author(s):  
Daniel F. Silva ◽  
Alexander Vinel ◽  
Bekircan Kirkici
Keyword(s):  
System Performance ◽  
Performance Metrics ◽  
Public Transit ◽  
Continuous Approximation ◽  
Efficient Operation ◽  
Fleet Sizing ◽  
On Demand ◽  
Single Vehicle ◽  
Transit Agencies ◽  
Using Data

With recent advances in mobile technology, public transit agencies around the world have started actively experimenting with new transportation modes, many of which can be characterized as on-demand public transit. Design and efficient operation of such systems can be particularly challenging, because they often need to carefully balance demand volume with resource availability. We propose a family of models for on-demand public transit that combine a continuous approximation methodology with a Markov process. Our goal is to develop a tractable method to evaluate and predict system performance, specifically focusing on obtaining the probability distribution of performance metrics. This information can then be used in capital planning, such as fleet sizing, contracting, and driver scheduling, among other things. We present the analytical solution for a stylized single-vehicle model of first-mile operation. Then, we describe several extensions to the base model, including two approaches for the multivehicle case. We use computational experiments to illustrate the effects of the inputs on the performance metrics and to compare different modes of transit. Finally, we include a case study, using data collected from a real-world pilot on-demand public transit project in a major U.S. metropolitan area, to showcase how the proposed model can be used to predict system performance and support decision making.

Development and testing of the FAST fuel performance code: Normal operating conditions (Part 1)

2015 ◽  
Vol 282 ◽  
pp. 158-168 ◽  
Author(s):  
A. Prudil ◽  
B.J. Lewis ◽  
P.K. Chan ◽  
J.J. Baschuk
Keyword(s):  
Operating Conditions ◽  
Fuel Performance ◽  
Normal Operating
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