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921.
Based on our analysis of the hopcount of the shortest path between two arbitrary nodes in the class G
p
(N) of random graphs, the corresponding flooding time is investigated. The flooding time T
N
(p) is the minimum time needed to reach all other nodes from one node. We show that, after scaling, the flooding time T
N
(p) converges in distribution to the two-fold convolution (2*) of the Gumbel distribution function (z)=exp (–e
–z
), when the link density p
N
satisfies Np
N
/(log N)3 if N . 相似文献
922.
We study a one-dimensional spin (interacting particle) system, with product Bernoulli (p) stationary distribution, in which a site can flip only when its left neighbor is in state +1. Such models have been studied in physics as simple exemplars of systems exhibiting slow relaxation. In our East model the natural conjecture is that the relaxation time (p), that is 1/(spectral gap), satisfies log (p)
as p0. We prove this up to a factor of 2. The upper bound uses the Poincaré comparison argument applied to a wave (long-range) comparison process, which we analyze by probabilistic techniques. Such comparison arguments go back to Holley (1984, 1985). The lower bound, which atypically is not easy, involves construction and analysis of a certain coalescing random jumps process. 相似文献
923.
方彝立 《宁波大学学报(理工版)》2002,15(2):51-53
引用1984年尹克震提出的“开关函数的反演公式”,采用伪随机序列技术的思想,提出移位寄存器型时序逻辑网络的一种快速设计方法。 相似文献
924.
M. Vatasescu F. Masnou-Seeuws 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):191-204
The paper contains a time-dependent investigation of the tunneling effect observed in the photoassociation spectrum of Cs2 and attributed to the 0g
-(6s, 6p
3/2) double well. When by photoassociation of two cold cesium atoms a vibrational level of the outer well is populated, tunneling
is an efficient mechanism for transferring the population to the inner well (R < 15a
0), where spontaneous emission may lead to formation of cold molecules in low vibrational levels of the a
3Σ+
u(6s, 6s) electronic state. This tunneling effect is analyzed by wavepackets propagation, first considering the double well potential
alone, and following a packet made by a superposition of states initially located at large distances. Characteristic times
for the vibration dynamics, corresponding to a beating phenomenon between the two wells, to partial “revival” at large distances,
and to maxima in the population localized in the inner well are reported and discussed. Second, we simulate the two-channels
a
3Σ+
u(6s, 6s)↦0g
-(6s, 6p
3/2) photoassociation at detunings around 2.9 cm-1: the inner well can be populated either by the excitation of a vibrational level of the external well (resonant excitation),
or by tuning the photoassociation laser at the energy of the inner well level which displays tunneling (“off-resonance excitation”).
In the first case the photoassociation is efficient, while the tunneling probability is small; in the second, the tunneling
probability is large, so that despite the poor efficiency of the photoassociation process, more population can be transferred
to the inner well. This second choice is shown to be very sensitive to the laser intensity, which could be used to control
the population of the inner well and hence the formation of ultracold molecules in low vibrational levels.
Received 19 April 2002 Published online 1st October 2002
RID="a"
ID="a"e-mail: francoise.masnou@lac.u-psud.fr 相似文献
925.
设计了一种水泥生产线自动化监控系统.并论证了系统的组成、工作原理、硬件设计和软件设计,该系统经过在府谷水泥厂投入使用以后,效果令人满意,具有较高的推广价值. 相似文献
926.
一类弱耦合时滞系统同步分支周期解的稳定性 总被引:2,自引:0,他引:2
利用Floquet指数理论讨论了一类弱耦合时滞系统同步分支周期解的稳定性.研究了当μ=0时系统分支周期解的存在性、稳定性及近似表达式. 相似文献
927.
为了寻求一种简单、有效的计算水平注水井与直井联合井网的见水时间的方法,将水平井简化为具有等效井筒半径的直井,考虑水平井与直井联合布井水驱油的非活塞性,运用等值渗流阻力法将渗流区划分为3个阻力区,推导出了五点法、七点法和九点法水平井与直井联合井网的油井见水时间的计算公式和修正公式。计算结果表明,井网的见水时间随水平井长度的增加而缩短;相同的井距和生产条件下,五点法井网的见水时间要长于九点法和七点法井网;随水平井与水平方向夹角的增大,五点法井网的见水时间缩短,七点法井网的见水时间先增加后缩短,九点法井网的见水时间增加;油藏和流体参数对井网见水时间影响不大。 相似文献
928.
CHEN Xiao-li TIAN Mao ZHOU Hui-lin 《武汉大学学报:自然科学英文版》2005,10(6):1005-1008
An important issue of ground-penetrating radar (GPR) signals analysis is de-noising thai is the guarantee of acquiring good detecting effect. The paper illustrates a successful application of digital single processor (DSP) based on wavelet shrinkage algorithm. In order to realize real-time GPP, signals analysis, some key issues are discussed such as the realization of fast wavelet transformation, the selection of CPU chip and the optimization of data movement. Experimenial results show that the DSP based application not only basically meets the real-time requirement of GPP, signals analysis, but also assures the quality of the GPR signals analysis. 相似文献
929.
Pollen records and time scale for the RM core of the Zoige Basin, northeastern QinghaiTibetan Plateau 总被引:2,自引:0,他引:2
SHENCaiming TANGLingyu WANGSumin LIChunhai LIUKam-biu 《科学通报(英文版)》2005,50(6):553-562
A continuous pollen record from the Zoige Basin in the northeastern Qinghai-Tibetan Plateau not only provides information on the vegetation and climate changes during the last two glacial/interglacial cycles, hut also gives proof to establish the time scale of the upper 60 m of the RM core. Subalpine spruce-fir forests colonized the Zoige Basin during the interglacials and interstadials, implying warm and wet climate conditions. Alpine periglacial desert or dry desert may have existed during the penultimate glacial and the last glacial maxima, respectively. Alpine sedge meadow dominated the landscape during MIS 4. The MIS 3 is punctuated by a number of stadials similar to those documented in the Guliya and GISP2 ice cores, as indicated by repeated rise and fall of subalpine spruce-fir forests. Our pollen record reveals a regional climate history similar to those from the neighboring sites, including the Arabian Sea and the Guliya ice core, and thus supports the notion that the Qinghai-Tibetan Plateau acts as an important link between climatic events in the North Atlantic realm and the Asian monsoon domain. 相似文献
930.