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101.
Syed SU Sreekumar J Gibson JR Taylor S 《Journal of the American Society for Mass Spectrometry》2011,22(8):1381-1387
We report here a study using a quadrupole mass spectrometer (QMS) in which a static magnetic field is applied transversely
to the body of the mass filter operating in stability zone 3. Significant improvement in QMS performance was obtained under
certain magnetic field conditions, and these have been explained in terms of our theoretical model. The theoretical approach
assumed in the model is that the QMS contains hyperbolic rods as electrodes and that the magnetic field acts over the full
length of the mass filter assembly. Our latest analysis also predicts for what values of operating parameters an enhancement
of the quadrupole resolution is achieved when a transverse magnetic field is applied. The model predicts instrument resolution
R > 5000 for Ar with a 100 mm long mass filter and R > 3500 for a HT and D2 mixture with a 200 mm long mass filter via application of a transverse magnetic field. 相似文献
102.
We show that any k-fold covering using translates of an arbitrary convex polygon can be decomposed into Ω(k) covers. Such a decomposition can be computed using an efficient (polynomial-time) algorithm. 相似文献
103.
104.
P M Voyles J E Gerbi M M Treacy J M Gibson J R Abelson 《Physical review letters》2001,86(24):5514-5517
Using fluctuation electron microscopy, we have observed an increase in the mesoscopic spatial fluctuations in the diffracted intensity from vapor-deposited silicon thin films as a function of substrate temperature from the amorphous to polycrystalline regimes. We interpret this increase as an increase in paracrystalline medium-range order in the sample. A paracrystal consists of topologically crystalline grains in a disordered matrix; in this model the increase in ordering is caused by an increase in the grain size or density. Our observations are counter to the previous belief that the amorphous to polycrystalline transition is a discontinuous disorder-order phase transition. 相似文献
105.
J. L. Friar B. F. Gibson G. L. Payne 《Zeitschrift für Physik A Hadrons and Nuclei》1981,301(4):309-318
Three nucleon ground state wave functions are displayed graphically in configuration space. Both the Schrödinger functions and the Faddeev amplitudes from which they are constructed are plotted. It is demonstrated that for the case where the two-nucleon interaction contains strong repulsion at short distances, the Faddeev amplitude bears no resemblance to the Schrödinger function, and is not even positive definite. Furthermore, the Faddeev amplitude is a much smoother function of the three independent coordinate variables, and is therefore much easier to calculate. Certain intuitive features of the Schrödinger wave function are seen to be present. 相似文献
106.
Gibson Richard A. Bennett Willard H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1974,2(3):174-181
The appearance of large amplitude oscillations and attenuation of beam current have been observed in high perveance electrically self-focused beams. These phenomena are shown to be due to instabilities produced by the interaction of the beam with its self-generated plasma. The critical current which must be exceeded for the instabilities to appear and the frequencies of the oscillations have been related to beam and background parameters and the dimensions of the experimental system. 相似文献
107.
108.
In this note fifth and sixth order PECE algorithms are presented. The corrector formulae are derived by using natural g-splines. The resulting PECE algorithms which use the Schoen predictor have larger regions of absolute stability and smaller truncation errors than the Krogh and Schoen algorithms of corresponding order. 相似文献
109.
S.F. Biagi M. Bourquin A.J. Britten R.M. Brown H. Burckhart A.A. Carter J.R. Carter Ch. Doré P. Extermann M. Gailloud C.N.P. Gee W.M. Gibson J.C. Gordon R.J. Gray P. Igo-Kemenes W.C. Louis T. Modis P. Mühlemann R. Weill 《Physics letters. [Part B]》1982,112(3):277-280
From a sample of 735 000 Ξ? decays, we have obtained a new upper limit for the branching ratio . The result is 1.9 × 10?5 at the 90% confidence level. 相似文献
110.
Ac impedance spectroscopy and neutron powder diffraction have been used to study the high temperature behaviour of defective
fluorite solid electrolytes. In yttria-stabilised zirconia with an yttrium content of 15 mol% YO1.5 there is a marked change in conductivity behaviour at around 650 °C, with a decrease in activation energy of 0.15 eV. Structural
studies confirm that this is due to a change in the bulk of the sample with the disappearance of diffuse scattering peaks
and marked changes in the behaviour of the isotropic temperature factors at the same temperature. These results indicate that
the change in activation energy of yttria-stabilised zirconia at 650 °C is due to an order-disorder transition involving local
defect clusters. In studies of zirconia co-doped with yttrium and niobium, activation energy for conduction is found to rapidly
increase with the concentration of the trivalent yttrium Saturation doping is reached at about 20–30 % of yttrium and activation
energy only increases slightly with doping. Introduction of pentavalent niobium at this level of doping serves to decrease
activation energy, although it also decreases conductivity slightly. The low and high temperature activation energies converge
as the saturation regime is approached. These observations seem to suggest that ordering of defect clusters into microdomains
increases activation energy for ionic motion. At low defect concentrations and high temperatures, this local ordering breaks
down and the activation energy for conduction decreases.
Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995 相似文献