نتایج جستجو برای: railroad
تعداد نتایج: 2280 فیلتر نتایج به سال:
One theory argues that state ownership of infrastructure is greater in poor countries because the social returns from investment exceed the private returns by a wider margin. Another theory argues that state ownership is greater when legal and political institutions provide weak enforcement of private property rights or weak limits on government excess. I test these theories using cross-country...
The Commander, Eighth Coast Guard District, issued a temporary deviation from the regulation governing the operation of the CSX Railroad Swing Span Bridge across Chickasaw Creek, mile 0.0, in Mobile, Alabama. The deviation is necessary to replace railroad ties on the bridge. This deviation allows the bridge to remain closed for eight hours on March 8, 2011. DATES: This deviation is effective fr...
Ballast degradation can cause poor drainage, settlement and reduced lateral stability, which adversely affect railroad track safety and performance. Two indices are commonly used in the North American railroad industry to quantify the level of ballast degradation. These are (i) Fouling Index (FI) and (ii) Percentage Fouling (PF). Identifying these two traditional indices involve ballast samplin...
The rolling surface for railroad wheels can be a heat source that may have an impact on the performance of the wheel bearing. In this study, experimental data from an electrically-heated railroad wheel set is analyzed by constructing thermal models of the wheel set. A steady finite-element model, a steady-analytical model, and a transient lumped-parameter model are discussed. Model parameters a...
Background and objective The Modified Look-Locker Inversion-Recovery (MOLLI) sequence (Messroghli, et al, JMRI, 2007) was optimized for myocardial T1 mapping on 1.5T. However, little data exists on T1 mapping at 3T. The standard MOLLI sequence uses three inversion-recovery blocks to acquire 11 images over 17 heartbeats (HB). The long breath hold could limit its clinical application in patients ...
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