scholarly journals Influence of time-dependent material degradation on life cycle serviceability of interspersed railway tracks due to moving train loads

2019 ◽  
Vol 199 ◽  
pp. 109625 ◽  
Author(s):  
Sakdirat Kaewunruen ◽  
Chayut Ngamkhanong ◽  
Jipong Ng
2008 ◽  
Vol 30 (2) ◽  
pp. 32-36 ◽  
Author(s):  
Christine Kovic

July 2007. Hundreds of Central American migrants were camped along the railway tracks in Arriaga, Chiapas waiting to for the freight train to leave. Some were eating, perhaps their last food for days, others had bottles of water tied across their shoulders, some attempted to rest under the train cars to escape the hot sun. One young man brushed his teeth under the trees, using the water he carried in a recycled coca-cola bottle, to prepare himself for the journey ahead. Arriaga, a town of 25,000 people, is split in half by the train tracks. The town's tiny plaza, with a small playground, fondas (eateries), and a railway museum, sits on one side of the tracks. The town's church and market lie on the other. These Central American migrants in Arriaga, some 150 miles from Mexico's southern border with Guatemala, were eager to jump the freight train to continue their journey north to the United States. The train had not left Arriaga for a full week and many were desperate as they felt trapped. Their preparations underscored the dangers and harshness of the trip. They would have to hold on to the train for hours and days at a time, riding on ladders and the roofs of tank cars. Those who fall asleep and lose their grip risk death or severe injury, such as dismemberment.


Proceedings ◽  
2018 ◽  
Vol 2 (16) ◽  
pp. 1142
Author(s):  
Mehmet Hamarat ◽  
Sakdirat Kaewunruen

A turnout, a component on modern railway tracks, provides operational flexibility by diverting the vehicles to different directions between two routes. [...]


2020 ◽  
Vol 12 (14) ◽  
pp. 5602
Author(s):  
Antonio Dominguez-Delgado ◽  
Helena Domínguez-Torres ◽  
Carlos-Antonio Domínguez-Torres

Energy refurbishment of the housing stock is needed in order to reduce energy consumption and meet global climate goals. This is even more necessary for social housing built in Spain in the middle of the last century since its obsolete energy conditions lead to situations of indoor thermal discomfort and energy poverty. The present study carries out a life cycle assessment of the energy and economic performance of roofs after being retrofitted to become cool roofs for the promotion of social housing in Seville (Spain). Dynamic simulations are made in which the time dependent aging effect on the energy performance of the refurbished cool roofs is included for the whole lifespan. The influence of the time dependent aging effect on the results of the life cycle economic analysis is also assessed. A variety of scenarios are considered in order to account for the aging effect in the energy performance of the retrofitted cool roofs and its incidence while considering different energy prices and monetary discount rates on the life cycle assessment. This is made through a dynamic life cycle assessment in order to capture the impact of the aging dynamic behavior correctly. Results point out significant savings in the operational energy. However, important differences are found in the economic savings when the life cycle analysis is carried out since the source of energy and the efficiency of the equipment used for conditioning strongly impact the economic results.


Author(s):  
Paul Jackson ◽  
David R. Wallace

Abstract This paper describes an approach for modeling product life-cycles to create time-dependent inventories for use in environmental impact assessment. A general process module is defined relating resource inputs and outflows, based upon an embedded mathematical model. Then, a parametric model to represent the average performance of manufacturing processes is proposed and used within modules. Different parameter values may be used to represent a variety of life-cycle processes. Individual modules are combined to form product life-cycle networks. Designers may specify the required system output (product demand) as a function of time and the integrated network calculates the necessary time-dependent resource flows throughout the network.


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