Systematic changes in mineral assemblages, mineral compositions, fluid inclusion characteristics, and hydrogen and oxygen isotope compositions in altered igneous rocks in the Bingham, Utah, porphyry copper deposit record the chemical and isotopic evolution of the hydrothermal solutions. Hydrothermal alteration in and surrounding the Bingham porphyry copper deposit consists of an outer propylitic zone of chlorite, epidote, and actinolite; a transition zone of hydrothermal biotite, actinolite, epidote, and chlorite; and an inner potassic zone of hydrothermal biotite and K-feldspar. Later sericitic and argillic alteration are superimposed on early potassic and propylitic alteration. Compositions of alteration minerals determined by electron microprobe methods are: biotite, mole fraction phlogopite (Mg/Mg + Fe) 0.58 to 0.83; actinolite, mole fraction tremolite (Mg/ Mg + Fe) 0.58 to 0.79; epidote, mole fraction pistacite (Fe/Fe + A1) 0.27 to 0.30; and chlorite, mole fraction clinochlore (Mg/Mg q-Fe) 0.66 to 0.76. Mineral compositions, especially MnO and MgO in chlorite, MnO in epidote, and TiO2 in biotite, vary systematically with distance from disseminated ore. MgO in chlorite increases from 20.6 to 24.6 wt percent. MnO in chlorite and vein epidote increases from less than 0.1 to 0.59 wt percent and from 0.08 to 0.73 wt percent, respectively. The average mole proportion Ti in biotite increases from 0.1 to 0.24.Temperatures and salinities from fluid inclusions range from greater than 600øC and 50 equiv wt percent NaC1 for the potassic zone to approximately 370øC and 33 wt percent for the propylitic zone. Coexisting liquid-rich and vapor-rich inclusions which homogenize at temperatures similar to the liquid and vapor phase, respectively, suggest boiling from the potassic core out to the potassic-propylitic transition zone. Compositions and homogenization temperatures for fluid inclusions suggest average P•//-T conditions which vary smoothly from the potassic core to the propylitic fringe: 600øC and 800 bars for the potassic zone, 450øC and 500 bars for the transition zone, and 350øC and 200 bars for the outer propylitic zone.Thermochemical calculations show that log faro decreases from 2.74 in the potassic core to 2.17 in the propylitic zone fringe, logfsa decreases from -1 to -3.3 in the core to -8.7 in the propylitic zone, and log foa decreases from -16 to -17.5 in the core to -29 in the same interval. The log activity ratios of Ca, Mg, and K to hydrogen ion increase from the potassic to the propylitic zone. K+/H + increases from 3.1 to 3.4, Mg+2/(H+) a increases from -2.25 to 4.25, and Ca+2/(H+) a increases from less than i to 7.75.The extent of oxygen isotope exchange between the hydrothermal vein fluids and the igneous rock matrix in the Bingham stock increases with increasing temperature, abundance of alteration and quartz veins, thickness of veins, and fracture intensity. All these parameters generally increase inward from the propylitic zone into the core of the potassic zone. Within the potassic zone, there is...

Most available wheel/rail interaction models for the prediction of impact forces caused by wheel flats use a Hertzian spring as contact model and do not account for the changes in contact stiffness due to the real three-dimensional wheel flat geometry. In the literature, only little information is available on how this common simplification influences the calculation results. The aim of this paper is to study the influence of contact modelling on simulated impact forces due to wheel flats in order to determine the errors introduced by simplified approaches. For this purpose, the dynamic wheel/rail interaction is investigated with a time-domain model including a three-dimensional (3D) non-Hertzian contact model based on Kalker's variational method. The simulation results are compared with results obtained using a two-dimensional (2D) non-Hertzian contact model consisting of a Winkler bedding of independent springs or alternatively a single non-linear Hertzian contact spring. The relative displacement input to the Hertzian model is either the wheel profile deviation due to the wheel flat or the pre-calculated vertical wheel centre trajectory. Both the 2D model and the Hertzian spring with the wheel centre trajectory as input give rather similar results to the 3D model, the former having the tendency to slightly underestimate the maximum impact force and the latter to slightly overestimate. The Hertzian model with the wheel profile deviation as input can however lead to large errors in the result. Leaving aside this contact model, the correct modelling of the longitudinal geometry of the wheel flat, is actually seen to have a larger influence on the maximum impact force than the choice of contact model.

The sound field in train compartments, treated as a series of connected air cavities, is modelled using statistical energy analysis, SEA. For the case under study, with five cavities in series and the source in the second cavity, a closed--form solution is obtained. An adjusted SEA model is used to predict the rate of spatial decay within a cavity. The SEA model is validated using results from a ray tracing method and from scale model measurements. For the octave bands 500-4000 Hz, good agreement is shown between the results from measurements, the ray tracing and the SEA model, for the two saloons closest to the source cavity (a vestibule). The SEA model was shown to slightly underestimate the rate of spatial decay within a cavity. It is concluded that a reasonable cause is the additional diffusion due to the seating.

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