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131.
G Viesti M Lunardon D Fabris G Nebbia M Cinausero E Fioretto G Prete JB Natowitz K Hagel R Wada 《Pramana》1999,53(3):395-404
The transition of the level density parameter a
off from the low excitation energy value a
off=A/8 MeV−1 to the Fermi gas value a
FG ∼ A/15 MeV−1 was discovered a few years ago studying particle spectra evaporated from hot compound systems of A∼ 160. A number of experiments have been recently performed to confirm the earlier findings and extend the investigation to
other mass regions and to higher excitation energies. Furthermore, precision coincidence experiments have been done in the
lead region in which evaporation residues are tagged by low energy gammarays. Those experiments open the possibility of a
detailed study of the level densities in nuclei where the shell effects are important. 相似文献
132.
A hybrid particle scheme is presented for the simulation of compressible gas flows involving both continuum regions and rarefied regions with strong translational nonequilibrium. The direct simulation Monte Carlo (DSMC) method is applied in rarefied regions, while remaining portions of the flowfield are simulated using a DSMC-based low diffusion particle method for inviscid flow simulation. The hybrid scheme is suitable for either steady state or unsteady flow problems, and can simulate gas mixtures comprising an arbitrary number of species. Numerical procedures are described for strongly coupled two-way information transfer between continuum and rarefied regions, and additional procedures are outlined for the determination of continuum breakdown. The hybrid scheme is evaluated through a comparison with DSMC simulation results for a Mach 6 flow of N2 over a cylinder, and good overall agreement is observed. Large potential efficiency gains (over three orders of magnitude) are estimated for the hybrid algorithm relative to DSMC in a simple example involving a rarefied expansion flow through a small nozzle into a vacuum chamber. 相似文献
133.
Topol IA Burt SK Russo N Toscano M 《Journal of the American Society for Mass Spectrometry》1999,10(4):318-322
The gas-phase acidities of glycine and alanine were determined by using a variety of high level theoretical methods to establish which of these would give the best results with accessible computational efforts. MP2, MP4, QCISD, G2 ab initio procedures, hybrid Becke3-LYP (B3LYP) and gradient corrected Becke-Perdew (BP) and Perdew-Wang and Perdew (PWP) nonlocal density functionals were used for the calculations. A maximum deviation of approximately 13 and 18 kJ/mol from experimental data was observed for the computed delta Hacid and delta Gacid values, respectively. The best result was obtained at G2 level, but comparable reliability was reached when the considerably less time consuming B3LYP, BP, and PWP density functional approaches were employed. 相似文献
134.
Research of both authors was supported in part by the N.S.F. 相似文献
135.
Burt Totaro 《K-Theory》1992,6(2):177-189
We identify the MilnorK-theory of a field with a certain higher Chow group. 相似文献
136.
Samsonov SV Phelps AD Bratman VL Burt G Denisov GG Cross AW Ronald K He W Yin H 《Physical review letters》2004,92(11):118301
A new method to generate ultrahigh-power microwave pulses compatible with mildly relativistic electron sources is proposed. This method involves a novel microwave compressor in the form of a metal helically corrugated waveguide, which can enhance the power of frequency-modulated nanosecond pulses up to the multigigawatt level. The results of the proof-of-principle experiments at kilowatt power levels are in good agreement with theory. 相似文献
137.
The nonlinear Klein-Gordon equation ?μ?μΦ + M2Φ + λ1Φ1?m + λ2Φ1?2m = 0 has the exact formal solution Φ = [u2m ?λ1um/(m ? 2)M2+λ12/(m?2)2M4?λ2/4(m ? 1)M2]1/mu?1, m ≠ 0, 1, 2, where u and v?1 are solutions of the linear Klein-Gordon equation. This equation is a simple generalization of the ordinary second order differential equation satisfied by the homogeneous function y = [aum + b(uv)m/2 + cvm]k/m, where u and v are linearly independent solutions of y″ + r(x) y′ + q(x) y = 0. 相似文献