نتایج جستجو برای: railroad
تعداد نتایج: 2280 فیلتر نتایج به سال:
This paper examines the historical impact of railroads on the American economy. Expansion of the railroad network and decreased trade costs may affect all counties directly or indirectly, an econometric challenge in many empirical settings. However, the total impact on each county can be summarized by changes in that county’s “market access,” a reduced-form expression derived from general equil...
We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad tank cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical...
Semantic query optimization can dramatically speed up database query answering by knowledge intensive reformulation. But the problem of how to learn the required semantic rules has not been previously solved. This chapter presents a learning approach to solving this problem. In our approach, the learning is triggered by user queries. Then the system uses an inductive learning algorithm to gener...
As World population is exponentially increasing big cities face traffic and safety challenges related to railroad and rapid ground transportation projects. For this reason, to avoid collisions and allow a better communication between train, central control headquarters, and passengers new technologies are being developed by means of very sophisticated technologies. This project, being focused i...
The broadband wireless access is emerging as a promising technology to meet the ever-increasing demand of M-commerce on the train. The traditional railroad communication system (RCS) is not only in charge of the traditional train scheduling, but also offers broadband WLAN services to passengers and provides the network platform to the intelligent railroad information system. This imposes a majo...
The current guidance provided for alignment studies stems largely from Wellington’s “Economic Theory of The Location of Railways” which discusses the problem of minimizing grades and curves on a transcontinental scale. However, modern engineers often find themselves working on a less grand scale with shorter projects such as industrial spur build-ins and urban by-passes, and needing to consider...
Even though rail transportation is one of the most fuel efficient forms of surface transportation, fueling costs are one of the highest operating cost head for railroad companies. In US, unlike Europe, fueling costs are indeed, by far, the single highest operating cost. For larger companies with several thousands of miles of rail network, the fuel bills often run into several billions of dollar...
While much has been written about the construction of Guayaquil and Quito railroad, little important connection between subsidiary companies organized by railroad development Ecuadorian Corporation, first modern holding company to be in Ecuador. The objective this article is present history Corporation from its beginnings 1897 with organization Railway Company dissolution 1986 as a result hosti...
A case-control study of lung cancer mortality in U.S. railroad workers in jobs with and without diesel exhaust exposure is reanalyzed using a new threshold regression methodology. The study included 1256 workers who died of lung cancer and 2385 controls who died primarily of circulatory system diseases. Diesel exhaust exposure was assessed using railroad job history from the US Railroad Retirem...
The dynamic performance of a railroad vehicle as related to safety is evaluated in terms of specific performance indices like ride quality. The ride quality is interpreted as the capability of the railroad vehicle suspension to maintain the motion within the range of human comfort and or within the range necessary to ensure that there is no damage to the cargo it carries. The recent trend in dy...
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