Three-Dimensional Modeling of Thermohydrodynamic Lubrication in Slider Bearings Using Streamline Upwind Petrov-Galerkin Method

A three-dimensional thermohydrodynamic lubrication model which couples the Reynolds and energy equations is developed in the finite-element program Sepran. The model uses the streamline upwind Petrov-Galerkin method. Model results indicate the peak temperature is not on the mid-plane surface. This position shifts toward the mid-plane as the width-to-length ratio is reduced from 10 to 1 as well as when pressure boundary conditions are altered in such a way that the inlet/outlet pressure is higher than the side pressure. The adiabatic temperature profiles of an infinite slider and a square slider are compared. The wider slider shows a higher peak temperature. The side flow plays a major role in determining the value and position of the peak temperature. Model results also indicate peak side flow at a width-to-length ratio of 2.     

Generation of Free Radicals in RDX and HMX Compositions

Efforts to generate detectable concentrations of free radicals in explosives, binders, and their mixtures are described. Radicals were readily produced in polycaprolactone and polyethylene glycol binders at liquid nitrogen temperature using stresses as low as 0.4 kbar. These radicals were all of the peroxy type, and presumably formed by reaction of mechano-radicals with oxygen present in the polymer. No mechano-radicals were observed from HMX or RDX using samples cooled to liquid nitrogen temperature and applied stresses up to 4 kbar. In neither impacted samples that failed to explode nor the residues remaining after a partial explosion were radicals detected by ESR. Low temperature γ-irradiation of these materials was also carried out. Free radical signals originating in both the polymer and the explosive could be identified. The reactivity of NO₂ radicals from γ-irradiated HMX is enhanced in the presence of binder. In γ-irradiated HMX/polycaprolactone mixtures, the NO₂ radical anneals rapidly at 150 K, versus 240 K for HMX alone. Evidence is presented to suggest that the relatively stable NO₂ radical (such as produced by γ-irradiation) in HMX does not play a dominant role in mechanical initiation.     

A study of the initial growth of PtxCo(1−x) thin films on Si3N4

Pt _x Co_{(1− x )} thin films where x  =0.24 have been deposited onto Si₃N₄ windows and studied using transmission electron microscopy. The films are used in ultrahigh-density recording studies and it was found that the surface of the substrate had a strong influence on the microstructure, crystallography and magnetic properties of the film. An investigation of the early growth of the film was made by studying films of different thickness between 100 and 300 Å. It was found that the grains were hexagonal in structure with a strong c -axis orientation perpendicular to the surface.     

Pyrochlore Phases in the System ZnO–Bi2O3–Sb2O5: I. Stoichiometries and Phase Equilibria

Two cubic pyrochlore phases exist in the system ZnO–Bi₂O₃–Sb₂O₅. Neither has the supposed "ideal" stoichiometry, Zn₂Bi₃Sb₃O₁₄. One, P ₁, is a solid solution phase, Zn_{2+ x} Bi_{2.96−( x − y )}Sb_{3.04− y} O_14.04+δ where 0< x <0.13(1), 0< y <0.017(2) and a =10.4285(9)−10.451(1) Å. The other, P ₂, is a line phase, Zn₂Bi_3.08Sb_2.92O_13.92 with a =10.462(2) Å. Subsolidus phase relations at 950°C involving phases P ₁ and P ₂ in the ZnO–Bi₂O₃–Sb₂O₅ phase diagram have been determined.     

Remote and in situ photogrammetric history of the Kidd Copper tailings site,Sudbury, Ontario

There is much concern regarding the genesis of acidic leachate by mine tailings and its potential impact on local water systems. Genesis of the leachate and its subsequent escape into the surrounding watershed is controlled by the primary distribution of facies within the tailings pond. Leachate generation and percolation is enhanced in high-sulphide coarse-grained sands, while percolation is restricted in fine-grained clays formed from bentonitic slimes. The Kidd Copper deposit, located on the South Range of the Sudbury Basin, was a typical offset dike nickel deposit, where mining took place between 1970 and 1990. Using a sequence of temporally separate aerial photographs dating from 1945 to 2002, it is possible to document the initial development of the mine, its closure and the subsequent degradation of the mine tailings waste that was produced during mining activity. Since the mine's closure, the resulting tailings deposit has progressively oxidized, generating acid-rich leachate. Leachate can escape from the tailings via surface run-off and subsurface flow. The spatial distribution of possible flow pathways was mapped using a combination of sub-centimetre-resolution real-time kinematic (RTK) GPS and individual, high-resolution, oriented photographs of subsurface pits. Lithologic mapping information of the Kidd Copper tailings deposit can provide an insight into the distribution of local aquifers and aquitards. Subsurface lithologic mapping was achieved using a combination of sub-centimetre-resolution RTK GPS and individual, high-resolution, oriented photographs of subsurface pits. The photograph of each pit provides lithologic information of a specific point in the tailings deposit, while the high-resolution GPS locates the individual photographs in three-dimensional (3D) geographic space. Combining these data allows us to identify continuous lithologic surfaces between pits, leading to the construction of a 3D model of the deposition of the tailings pond. Grain size and textural details extracted from the images of each lithology permit discrimination between aquifers and aquitards. The final geometric model could be used as input for estimating the hydrologic and chemical evolution of the tailings.     

Discussion of paper

In the spring of 1993, the Utah Special Improvement District project was initiated to improve sidewalks, curb and gutters, and driveway approaches (aprons) in Salt Lake City. One of the critical problems faced during this project was how to recommend the most appropriate treatment decision at the roadway improvement job sites. Therefore, the research was conducted to demonstrate the use of an expert system on a portable computer at the construction job site. A prototype Portable Inspection Expert System (PIES) was developed based on the following factors: displacement, surface condition, water effect, tree root effect, and condition of adjacent sections. PIES can decide if replacement, jacking, or do nothing treatment of concrete sections is required.

PIES program was developed by using “KnowledgePro Windows” expert system shell, and installed in “Dauphin DTR-1” pen-based portable computer. One of the major benefits of using an expert system on a portable computer is that it can combine the necesary information on the distress condition of the facilities and help the inspectors make appropriate decision at construction job sites. PIES had been tested with two engineers and a follw-up survey was conducted after the test. Feedback from the survey was analyzed to improve limitations. The current inspection process for the Utah Special Improvement District project was improved by using a consistent decision rule of PIES.     

Gas temperature measurements in weakly ionized glow discharges with filtered Rayleigh scattering

We report the first gas temperature measurements in plasmas to our knowledge obtained by filtered Rayleigh scattering (FRS). A narrow-linewidth Ti:sapphire laser is used as the illumination source, and a mercury filter provides strong suppression of elastic background. We perform measurements in weakly ionized glow discharges in pure argon and in an argon-plus-1%-nitrogen mixture. Where possible, we verify the FRS technique by comparing filtered measurements with unfiltered measurements. We present point measurements of axial temperature with uncertainties of less than 5%. We use a planar scheme to obtain radial temperature profiles with uncertainties of 10%.     

Use of a model data set to test methods for mapping radon potential

It is difficult to test the accuracy of mapping methods using real measurement data of radon levels in houses, as different methods produce different maps, and there is no standard to compare them with. A model data set, Linevar, was therefore constructed, having features which allow the accuracies of different mapping methods to be compared. Data for Linevar were generated such that they had a geometric mean that varied across the map in a pattern of stripes of higher and lower radon potential. with widths of 1, 2, 4, and 8 km over an area 100 km square. The geometric standard deviation was kept at a constant value. Data were generated at densities varying from 1 to 100 results per 1 km grid square in different parts of the map. The data set was used to develop a mapping method that shows as much detail as possible without generatin, artefacts.     

Subsidence in impaction grafting: the effect of adding a ceramic bone graft extender to bone

The incidence of revision total hip arthroplasty is increasing dramatically and the associated demand for allograft bone is likely to exceed the available supply. In addition, allograft presents potential problems with regard to infection, antigenicity, availability, reproducibility and cost. It is therefore desirable to develop an alternative to allograft. This study investigated BoneSave, a porous tricalcium phosphate-hydroxyapatite ceramic for use in impaction grafting of the femur at revision total hip arthroplasty. The findings of an in vitro mechanical study comparing the initial stability of pure allograft, a volume mixture of 50 per cent allograft and 50 per cent BoneSave, and a volume mixture of 10 per cent allograft and 90 per cent BoneSave are reported. The BoneSave-allograft mixtures exhibit both much greater mechanical stability and reproducibility than the pure allograft (p < 0.05) at all tested loads (200-800 N). At high peak loads the high volume (90%, v/v) BoneSave mix also provided higher mechanical stability than the medium volume (50 per cent BoneSave-50 per cent allograft) mix (p < 0.05). These results demonstrate thatfrom a mechanical standpoint the tested ceramic provides adequate initial stability to be used as a bone graft extender with allograft in impaction grafting of the femur.