A novel constraint model for scheduling train trips on a network of tracks used in both directions is described. We argue that a generalization of a job-shop scheduling formulation can drastically decrease the problem size. Preliminary complexity and performance results and a set of examples of schedules generated by our implementation are presented.

This paper presents the results of a field investigation in the unsaturated, fractured welded tuff within the Exploratory Studies Facility (ESF) at Yucca Mountain, NV. This investigation included a series of tests during which tracer-laced water was released into a high-permeability zone within a horizontal injection borehole. The tracer concentration was monitored in the seepage collected in a...

The 40Ar/39Ar geochronology method is capable of high precision (<0.05%), but remains limited by relatively large uncertainties in 40K decay constants and the ages natural reference mineral standards. most widely used well-known ca. 28 Ma Fish Canyon Tuff sanidine (FCTs). Several studies have attempted to calibrate FCTs against astronomically tuned tephra Crete (Faneromeni A1 tephra) Morocco (M...

We present the stratigraphy, lithology, volcanology, and age of the Acahualinca section in Managua, including a famous footprint layer exposed in two museum pits. The ca. 4-m-high walls of the main northern pit (Pit I) expose excellent cross sections of Late Holocene volcaniclastic deposits in northern Managua. We have subdivided the section into six lithostratigraphic units, some of which we c...

Douglas Creek arch in western Colorado and eastern Utah separates the Uinta and Piceance Creek basins. During deposition of the lower part of the Eocene Green River Formation, the arch provided a physical barrier dividing ancient Lake Uinta into two segments. As the lake expanded, the arch became a shoal area where marginal-lacustrine and mud flat sediment was deposited. Near the end of Green R...