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91.
Y. Y. Lau K. R. Chu L. R. Barnett V. L. Granatstein 《International Journal of Infrared and Millimeter Waves》1981,2(3):373-393
The operation of the gyrotron travelling wave amplifier is based on the convective cyclotron maser instability. It is found that this convective instability may become absolute (nonconvective) at a sufficiently high current level, resulting in oscillation instead of amplification. This threshold current for the transition depends sensitively on the applied magnetic field. The axial wavelength and the characteristic frequency of oscillation at the onset of absolute instability are given. It is found that momentum spread has virtually no effect on the threshold current. A small amount of resistive wall loss, however, raises the threshold current significantly. Oscillations due to partial reflection at the ends of the system are also examined. Preliminary experimental results on both types of oscillations are reported and are found to be in good agreement with the theory. 相似文献
92.
A comprehensive study indicates that equally likely sources for trimuon events neutrino scattering are (a) charged heavy lepton production (with decay to three muons) and (b) simultaneous production of a neutral lepton (with decay to two muons) and a heavy quark (with decay to one muon). The sequential decay of a heavy quark to two muons is less likely. An intriguing model yielding simultaneous M0 and b quark production is proposed. 相似文献
93.
W. Mark Barnett Geng Lin Harvest L. Collier Russell G. Baughman 《Journal of chemical crystallography》1997,27(7):423-427
1,1′-Di(methylacetato)-2,2′-biimidazole, C12H14N4O4, crystallizes from methanol in the space groupP2 1/c, wherea=9.535(2),b=13.385(2),c=5.1208(8) Å,V=652.2(2) Å3, andZ=4.1,1′-Di(chloroethoxyethyl)-2,2′-biimidazole, C14H20Cl2N4O2, crystallizes from cyclohexane in the space groupPbca, wherea=12.372(2),b=8.959(2),c=14.840(2) Å,V=1644.9(5) Å3, andZ=8. The structures were refined toR=0.041 (1380 observed reflections) andR=0.043 (3243 observed reflections), respectively. Both molecules crystallize with coplanar rings and the substituents assume atrans configuration with a center of inversion between the bridging carbon atoms. 相似文献
94.
The signal-to-noise ratio in steliar speckle interferometry is estimated by direct application of photon counting formulae. This treatment demonstrates that the limiting observable magnitudes are dependent on object size. 相似文献
95.
96.
Absorption and fluorescence spectra of Sn2+ and Sb3+ in borax, phosphate, and germanate glasses were measured in the temperature range 87–295°K. Fluorescence decay times of these ions in borax glass at 87°K was a single exponent with τ ≈ 6–11 μsec. At 293°K, two decay times were resolved in the range of 50–2000 nsec. The nonexponential behavior is interpreted by the repopulation of the 3P1 level from the 3P0 level. The temperature dependence of fluorescence and the low values of quantum efficiencies of fluorescence are explained by means of the configurational coordinate diagram model. 相似文献
97.
Comments on “The matrix sign function and computations in systems” by E. D. Denman and A. N. Beavers
Stephen Barnett 《Applied mathematics and computation》1978,4(3):277-279
The suggested method of Denman and Beavers for solving a Lyapunov matrix equation is shown to fail when the solution is not unique. It is also shown that sgnA can be used to determine the inertia of A. 相似文献
98.
R.Michael Barnett Goran Senjanović L. Wolfenstein D. Wyler 《Physics letters. [Part B]》1984,136(3):191-195
Phenomenological consequences of a light neutral Higgs scalar S (mass < 3.7 GeV) are explored in various two-Higgs-doublet models where some of the couplings are strongly enhanced. In one class of models the two-gluon decay mode is predominant, and decays into two muons are quite suppressed. A detailed analysis of the decay b → s + S is given. The consequences a light scalar for supersymmetric models are discussed. 相似文献
99.
Barnett ND Clegg W Kennedy AR Mulvey RE Weatherstone S 《Chemical communications (Cambridge, England)》2005,(3):375-377
Relevant to mixtures studied in solution and utilised in styrene polymerisation but hitherto not characterised in the solid, two crystal structures of alkali metal alkoxide-magnesium bis(alkyl) co-complexes have been determined, revealing that in binding to the C2O tripodal face of a common organomagnesiate anion, Na+ prefers O-coordination, whereas K+ prefers C-coordination. 相似文献
100.
Barnett R. Parker 《European Journal of Operational Research》1982,11(4):325-337
Recent attempts at consumer participation in the health care planning process have proved weak in their ability to responsively account for consumer health welfare. This can be attributed, in large part, to the mechanisms employed for identifying and utilizing the consumer's health care views and preferences. A heuristic planning procedure designed to overcome these problems by directly incorporating consumer preferences is developed. It identifies that (primary) health care delivery system which maximizes total incremental health benefit to a community subject to a prespecified budget constraint. The model assumes a methodology (previously developed by the author) for measuring, in aggregable units, the benefit, Bip, from some health care facility p as perceived by some consumer i. Application of the procedure and subsequent sensitivity analyses demonstrate its ability to generate valid solutions that are robust to disturbances in the planning system. 相似文献