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131.
A Note on Sampling from Combinations of Distributions 总被引:1,自引:0,他引:1
A rejection technique is described for sampling from a combinationof distributions with negative weights for some of the components. 相似文献
132.
In this paper, it is demonstrated how a direct stiffness method for wavepropagation in multilayered saturated poroelastic media, based on integraltransform techniques, can be modified to account for a small amount of gasin the pores. Unsaturated media with small gas fractions can be treatedusing Smeulders extension of Biots poroelastic theory. The effect of thepresence of gas bubbles on the fluid bulk modulus and the dispersioncharacteristics of a water-saturated sand of Mol is demonstrated. Thedirect stiffness method is illustrated with a numerical example wheretransient wave propagation in a dry, saturated and unsaturated halfspaceis considered. 相似文献
133.
134.
Directional wave field decomposition can be accomplished with the aid of pseudo-differential operators. A fast numerical scheme
requires sparse matrix representations of these operators. This paper focuses on designing sparse matrices for the propagator
while keeping the accuracy high at the cost of ignoring critical-angle phenomena. The matrix representation follows from a
rational approximation for the square root operator and the derivatives. The parameterization thus introduced lends itself
to an overall optimization procedure that minimizes the errors for a chosen discretization rate. As such, the approach leads
to an accurate propagator up to the (local) critical angle on a coarse numerical grid.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
135.
Pulsed power levels in excess of 5 kW at wavelengths near 1.2 mm have been obtained via optical pumping of 13C H3F in a 3 m, mirrorless waveguide laser, using a CO2 TEA laser as a source of pump radiation. 相似文献
136.
P. Woskoboinikow Z. Drozdowicz K. Isobe D.R. Cohn R.J. Temkin 《Physics letters. A》1976,59(4):264-266
A D2O oscillator-amplifier laser system has been developed that produces 12.7 mJ pulses with a peak power level of 195 kW at a wavelength of 384.6 μm. The linewidth was measured to be 70 MHz FWHM and an efficiency of 0.11% was observed. 相似文献
137.
The time-resolved tryptophyl fluorescence of alpha-chymotrypsin A and alpha-chymotrypsin in the crystalline state and in buffer solution at room temperature was analyzed globally. Triple-exponential decay functions are necessary to adequately describe the tryptophyl fluorescence decay surfaces of the protein powders as a function of hydration and in solution. The fluorescence lifetimes of alpha-chymotrypsinogen A (tau 1 = 0.32, tau 2 = 1.30 ns, tau 3 = 3.98 ns) and alpha-chymotrypsin(tau 1 = 0.66 n s, tau 2 = 2.26 ns, tau 3 = 5.40 ns) are constant over the entire hydration range. The spectral positions of the decay-associated spectra of the hydrated powders do not shift as a function of hydration. This indicates that the structures of the zymogen and the active enzyme are unaffected by hydration. The lifetimes of alpha-chymotrypsinogen A in phosphate buffer pH 7.4 are tau 1 = 0.37 ns, tau 2 = 1.17 ns and tau 3 = 3.44 ns while the respective values of alpha-chymotrypsin are tau 1 = 0.47 ns, tau 2 = 1.40 and tau 1 = 3.89 ns. 相似文献
138.
O. N. Temkin L. G. Bruk D. S. Zakharova K. Yu. Odintsov E. A. Katsman I. V. Petrov O. Yu. Istomina 《Kinetics and Catalysis》2010,51(5):691-703
A kinetic study of cyclohexene oxidation by p-quinones in water-acetonitrile solutions of cationic Pd(II) complexes has been carried out for the first time. The observed kinetic regularities (dependence of the initial rate on the HClO4 and p-benzoquinone concentrations) and the shape of the kinetic curves differ radically from those for the chloride systems. The unsteady-state process can be described only under the assumption that complexes of reduced palladium species with quinones are catalytically active forms. The role of solvated palladiumcarbenium ions in particular steps of the mechanism is discussed. 相似文献
139.
Michael Temkin 《Advances in Mathematics》2008,219(2):488-522
Grothendieck proved in EGA IV that if any integral scheme of finite type over a locally noetherian scheme X admits a desingularization, then X is quasi-excellent, and conjectured that the converse is probably true. We prove this conjecture for noetherian schemes of characteristic zero. Namely, starting with the resolution of singularities for algebraic varieties of characteristic zero, we prove the resolution of singularities for noetherian quasi-excellent Q-schemes. 相似文献
140.
L. G. Bruk O. N. Temkin A. S. Abdullaeva E. A. Timashova E. Yu. Bukina K. Yu. Odintsov I. V. Oshanina 《Kinetics and Catalysis》2010,51(5):678-690
PdX2-organic solvent-water solutions, where X = halide (preferably bromide or iodide) and the organic solvent is 1,4-dioxane or
tetrahydrofuran, are suggested as catalytic systems for CO oxidation. A number of coupled processes take place in these systems.
The kinetics and mechanism of CO oxidation by oxygen in the PdI2-LiI-1,4-dioxane-water system are reported. Cyclohexene hydrocarboxylation into cyclohexanecarboxylic acid can be carried
out as part of the coupled process occurring in the PdBr2-tetrahydrofuran-water system. 相似文献