3,567 research outputs found

    OGO-3 observations of ELF noise in the magnetosphere - Part 1 - Spatial extent and frequency of occurrence

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    OGO-3 spectrum analyzer measurements of magnetic noise in magnetospher

    Simulation of the Pion Decay Channel of a Neutrino Factory

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    In the pion decay channel of a neutrino factory the particles are transported in a solenoidal magnetic field, a 1.8 T constant field in the CERN reference scenario. Increasing the field strength decreases the transverse emittance of the decay muons. To define a lower limit on the achievable u emittance, the reference scenario is compared with a study case where pions decay in a field of 20 T. This simulation shows that in any realistic scenario the u emittance will only reduced by less than 21 in each transverse plane as compared to the reference scenario, and at the expense of an increase in longitudinal emittance

    Gibbs free energy difference between the undercooled liquid and the beta-phase of a Ti-Cr alloy

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    The heat of fusion and the specific heats of the solid and liquid have been experimentally determined for a Ti60Cr40 alloy. The data are used to evaluate the Gibbs free energy difference, DELTA-G, between the liquid and the beta-phase as a function of temperature to verify a reported spontaneous vitrification (SV) of the beta-phase in Ti-Cr alloys. The results show that SV of an undistorted beta-phase in the Ti60Cr40 alloy at 873 K is not feasible because DELTA-G is positive at the temperature. However, DELTA-G may become negative with additional excess free energy to the beta-phase in the form of defects

    Gibbs free-energy difference between the glass and crystalline phases of a Ni-Zr alloy

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    The heats of eutectic melting and devitrification, and the specific heats of the crystalline, glass, and liquid phases have been measured for a Ni24Zr76 alloy. The data are used to calculate the Gibbs free-energy difference, DeltaGAC, between the real glass and the crystal on an assumption that the liquid-glass transition is second order. The result shows that DeltaGAC continuously increases as the temperature decreases in contrast to the ideal glass case where DeltaGAC is assumed to be independent of temperature

    Mechanically driven alloying and grain size changes in nanocrystalline Fe-Cu powders

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    Highly supersaturated nanocrystalline FexCu100-x alloys (10 less-than-or-equal-to x less-than-or-equal-to 95) have been prepared by mechanical alloying of elemental crystalline powders. The development of the microstructure is investigated by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The results are compared with data for ball-milled elemental Fe and Cu powders, samples prepared by inert gas condensation, and sputtered films. The deformation during milling reduces the grain size of the alloys to 6-20 nm. The final grain size of the powders depends on the composition of the material. Single-phase fcc alloys with x less-than-or-equal-to 60 and single-phase bcc alloys with x greater-than-or-equal-to 80 are formed even though the Fe-Cu system exhibits vanishingly small solid solubilities under equilibrium conditions. For 60 less-than-or-equal-to x less-than-or-equal-to 80, fcc and bcc solid solutions coexist. The alloy formation is discussed with respect to the thermodynamic conditions of the material. The role of the large volume fraction of grain boundaries between the nanometer-sized crystals, as well as the influence of internal strains and stored enthalpies introduced by ball milling, is critically assessed

    Collisionless solar wind protons: A comparison of kinetic and hydrodynamic descriptions

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    Kinetic and hydrodynamic descriptions of a collisionless solar wind proton gas are compared. Heat conduction and viscosity are neglected in the hydrodynamic formulation but automatically included in the kinetic formulation. The results of the two models are very nearly the same, indicating that heat conduction and viscosity are not important in the solar wind proton gas beyond about 0.1 AU. It is concluded that the hydrodynamic equations provide a valid description of the collisionless solar wind protons, and hence that future models of the quiet solar wind should be based on a hydrodynamic formulation

    A study of waves in the earth's bow shock

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    The perturbation vectors of waves up and downstream from the region of maximum compression in the bow shock were examined on OGO-5 under particularly steady solar wind conditions. The polarization of the upstream waves was RH, circular and of the downstream waves LH, elliptical in the spacecraft frame. By observing that the polarization of the waves remained unchanged as the shock motion swept the wave structure back and forth across the satellite three times in eight minutes, it was found that the waves were not stationary in the shock frame. A study of the methods of determining the shock normal indicates that the normal estimated from a shock model should be superior to one based upon magnetic coplanarity. The propagation vectors of the waves examined did not coincide with the shock model normal, the average magnetic field, or the plasma flow velocity. However, the major axis of the polarization ellipse of the downstream wave was nearly parallel to the upstream propagation vector

    A simple approach to fairer hospital benchmarking using patient experience data

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    Objective To determine the factors contributing most to variability in patient experience in order to present approaches for fairer benchmarking of hospitals and for quality improvement. Design Secondary analysis of data from a widely used survey on patient experience. Setting Inpatients from all 24 acute hospitals in the Canton of Bern in Switzerland. Data collection followed the standardized and validated Picker Institute methodology for a period of 13 weeks in the fall/winter of 2005. Participants Inpatients age 18 years and older (n = 14 089), discharged within the sampling period. Main outcome measures ‘Patient experience', measured by the total Picker Problem Score (PPS) and by six domain scores (care, communication, respect, cooperation, organization, discharge management). Results In regression analysis, the patient factors self-reported health, age and education explained the highest proportion of variability in the PPS (4.8, 2.2 and 0.7%, respectively). Multiple linear adjustment for factors associated with patients removed between 29 and 33% of variability between hospital categories. The domain score means varied from under 5% for ‘respect towards the patient' to 34% for ‘discharge management'. Ranking of hospitals by domain scores differed from the ranking based on the total PPS. Conclusions Statistical adjustment for patient mix and additional stratification for some hospital factors make benchmarking using patient survey data fairer and more transparent. Use of our approach for presenting quality data may make interpretation easier for the different target groups and may enhance the relevance of such information for decision-makin
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