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1.
It is known that under resonance conditions, a group of strongly interacting bosonic atoms, trapped in a double-well potential, mimics a single particle, performing Rabi oscillations between the wells. By implication, all atoms need to tunnel at roughly the same time, even though the Bose–Hubbard Hamiltonian accounts only for one-atom-at-a-time transfers. The mechanism of this collective behavior is analyzed, the Rabi frequencies in the process are evaluated, and the limitation of this simple picture is discussed. In particular, it is shown that the small rapid oscillations superimposed on the slow Rabi cycle result from splitting the transferred cluster at the sudden onset of tunnelling, and disappear if tunnelling is turned on gradually. 相似文献
2.
3.
This paper deals with a computational analysis of the influence of the pressing method and part geometry on the final density
distribution in the cold compaction process of ceramic alumina powders. The analysis is based on the explicit finite-element
model proposed and validated in a previous study. The mechanical behavior of the processing material is described using a
multisurface elastoplastic model, the modified Drucker-Prager/Cap model
Published in Prikladnaya Mekhanika, Vol. 43, No. 10, pp. 129–134, October 2007. 相似文献
4.
5.
对短程飞行时间法(tim e-of-flight,TOF)中推算冷原子温度的理论拟合公式与近似拟合公式进行了误差分析与比较。研究表明:对于使用短程飞行吸收光谱信号推测冷原子团温度,当探测光光斑半径与冷原子团高斯半径之比k小于0.2时,理论拟合公式和近似拟合公式能很好的相符,随着探测光光斑半径与冷原子团高斯半径比值的逐渐增大,用近似拟合公式所得TOF吸收信号与用理论拟合公式所得TOF吸收信号的误差也将逐渐增大,当比值为0.5时,用近似拟合公式所得TOF吸收信号的误差将增大到20%。 相似文献
6.
Richard P. Fischer Arne W. Fliflet 《International Journal of Infrared and Millimeter Waves》2002,23(9):1297-1313
This paper presents the design and test of asymmetric quasioptical resonators for gyrotron applications, where most of the diffraction output coupling comes from the smaller of two mirrors. A computer code based on scalar diffraction theory is used to calculate the resonator losses and the electric field near the mirrors. Resonators with mirror separations approaching confocal have reduced side lobes in the diffraction patterns, which should allow for better power transmission and focusing. Cold tests have been performed at 94 and 141 GHz to measure the quality factor of the asymmetric resonators as a function of mirror separation and mirror misalignment. Typical resonator parameters include 65 cm mirror separation, 1-3% output coupling and 85% of the losses from the small mirror. A half-symmetric resonator with one flat and one curved mirror has also been investigated. The calculated values of Q are in reasonably good agreement with the cold test measurements. 相似文献
7.
8.
A series of ethynyl and ethenyl end-capped imide resins were synthesised by the reaction of 9,9-bis(4-aminophenyl) fluorene
(BAF) with pyromellitic dianhydride (PMDA)3/3′, 4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxy
phenyl) hexafluoropropane dianhydride (6F) and 3-ethynyl aniline/maleic anhydride. Structural characterisation was done by
infra red and elemental analysis. Thermal characterisation was done by differential scanning calorimetry and thermogravimetric
analysis. The decomposition temperatures of cured resins were above 200°C in nitrogen atmosphere. Char yield at 800°C ranged
from 59–65.5%. 相似文献
9.
冷态德士古气化炉流场与停留时间分布的研究 总被引:5,自引:1,他引:5
测定了德士古气化炉的冷态速度分布和停留时间分布。结果表明:德士古气化炉内在轴向2.5~3.0倍直径范围内存在回流,最大回流量为射流量的3.5倍左右;在平均停留时间之前,已有50%左右的物料逸出炉外。本文指出,德士古气化炉中存在的问题,如结渣、耐火砖寿命短、有效气体成分偏低均与炉内流场有关。 相似文献
10.
The cold and heat denaturations of bovine P-lactoglobulin A ((β-lg A) has been studied in solutions of guanidine hydrochloride
(GuHCI) by differential scanning calorimetry (DSC). The experimental results are presented and discussed. It is shown that
the number of protons bound by the monomeric molecules of β-lg A was unchanged before and after its heat denaturation below
pH 3, and that the activation energy of the heat denaturation was depressed owing to the presence of GuHCI. In the solutions
with 2.50 and 3.06 mol/L of GuHCI, both the cold and heat denaturations of P-lg A were observed. In comparison with the heat
denaturation, the activation energy of cold denaturation was far lower and the number of GuHCl molecules bound by the unfolded
polypeptide chains after culd denaturation increased a lot. The absolute value of the enthalpy of cold denaturation was larger
than that of heat denaturation. It was found by the analysis that the contribution to the total denaturational enthalpy of
conformational change itself of the monomeric molecules of β-lg A was the lowest among the globulins, according to the average
of the number of heavy atoms.
Project supported by the National Natural Science Foundation of China, and by the fund for excellent items under Director
of the Institute of Chemistry. 相似文献