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161.
时间序列散斑干涉场中相位函数的计算 总被引:1,自引:2,他引:1
散斑干涉或电子散斑干涉计量应用于连续运动或变形物体时,就会产生一个时变的散斑干涉场,通过摄像系统连续地采集这一时变散斑场,可获得一系列时间序列散斑干涉图,通过对序列散斑图上各点在时间轴上光强值的变化进行分析,提出了一种基于时间序列的分析方法,用以提取干涉场的相位值,进而获得物体全场变形信息。 相似文献
162.
张红玉 《数学的实践与认识》2010,40(11)
针对于微分方程数值解,介绍了一种新的误差估计方法.方法证实了伪谱方法具有精度高速度快的优点,进而引出了修正的伪谱方法. 相似文献
163.
O. Penrose Joel L. Lebowitz J. Marro M. H. Kalos A. Sur 《Journal of statistical physics》1978,19(3):243-267
The results of computer simulations of phase separation kinetics in a binary alloy quenched from a high temperature are analyzed in detail, using the ideas of Lifshitz and Slyozov. The alloy was modeled by a three-dimensional Ising model with Kawasaki dynamics. The temperature after quenching was 0.59T
c, whereT
c
is the critical temperature, and the concentration of minority atoms was=0.075, which is about five times their largest possible single-phase equilibrium concentration at that temperature. The time interval covered by our analysis goes from about 1000 to 6000 attempted interchanges per site. The size distribution of small clusters of minority atoms is fitted approximately byc
1(1-)3
w(t),c
1 (1–)4
Q
l
w(t)l(2l10); wherec
l
is the concentration of clusters of sizel;Q
2,...,Q
10 are known constants, the cluster partition functions;t is the time; andw(t)=0.015(1+7.17t
–1/3). The distribution of large clusters (l20) is fitted approximately by the type of distribution proposed by Lifshitz and Slyozov,c
l
,(t)=–(d/dl)
[lnt+p
(l/t)], where is a function given by those authors and is defined by(x)=C
o
e–x-C
1
e
–4x/3-C
2
e
–5x/3;C
0,C
1,C
2 are constants determined by considering how the total number of particles in large clusters changes with time.Supported by the U.S. Air Force Office of Scientific Research under Grant No. 78-3522 and by the U.S. Department of Energy under Contract No. EY-76-C-02-3077*000. 相似文献
164.
用金刚石压砧高压X光衍射技术研究了Ⅱ-Ⅵ族化合物CdTe的室温状态方程和室温高压相变。实验的最高压力达39.2 GPa。实验中发现CdTe从(3.3±0.1)GPa开始从闪锌矿结构相相NaCl结构相转变,相变时体积收缩15.8%;从(10.3±0.2)GPa开始从NaCl相向β-Sn结构相转变,相变时无体积突变;在(12.2±0.2)GPa由β-Sn相向正交结构相转变,相变时也无体积突变。CdTe的压缩数据用最小二乘法以Bridgman状态方程和Murnaghan状态方程拟合,得到其零压时合相变压力时各个相的体弹模量及体弹模量的压力微商,并与其它的实验合理论结果进行比较。 相似文献
165.
Walter Schempp 《Acta Appl Math》1997,48(2):185-234
Due to its unequalled advantages, the magnetic resonance imaging (MRI) modality has truly revolutionized the diagnosis and evaluation of pathology. Because many morphological anatomic details that may not be visualized by other high tech imaging methods can now be readily shown by diagnostic MRI, it has already become the standard modality by which all other clinical imaging techniques are measured. The unique quantum physical basis of the MRI modality combined with the imaging capabilities of current computer technology has made this imaging modality a target of interdisciplinary interest for clinicians, physicists, biologists, engineers, and mathematicians. Due to the fact that MRI scanners perform corticomorphic processing, this modality is by far more complex than all the other high tech clinical imaging techniques. The purpose of this paper is to outline a phase coherent wavelet approach to Fourier transform MRI. It is based on distributional harmonic analysis on the Heisenberg nilpotent Lie group G and the associated symplectically invariant symbol calculus of pseudodifferential operators. The contour and contrast resolution of MRI scans which is controlled by symplectic filter bank processing gives the noninvasive MRI modality superiority over X-ray computed tomography (CT) in soft tissue differentiation. 相似文献
166.
D. Dantchev J. Rudnick 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(2):251-268
We study the behavior of systems in which the interaction contains a long-range component that does not dominate the critical
behavior. Such a component is exemplified by the van der Waals force between molecules in a simple liquid-vapor system. In
the context of the mean spherical model with periodic boundary conditions we are able to identify, for temperatures close
above T
c, finite-size contributions due to the subleading term in the interaction that are dominant in this region decaying algebraically as a function of L. This mechanism goes beyond the standard formulation of the finite-size scaling but is to be expected in real physical systems.
We also discuss other ways in which critical point behavior is modified that are of relevance for analysis of Monte Carlo
simulations of such systems.
Received 21 November 2000 and Received in final form 28 February 2001 相似文献
167.
李晓康 《纯粹数学与应用数学》2010,26(5):776-784
为对基金净值数据进行建模,根据基金净值样本数据的尾部特点,建立极大,极小值分布的GPD模型,运用POT方法确定临界值,进而对参数进行估计,并对模型进行检验.最后,运用建立的模型对一些极值点进行预测.所得结果很好地描述了数据特点,对极值点的预测符合实际. 相似文献
168.
MA YuQiang 《理论物理通讯》1999,31(4):537-542
We propose a soluble quantum spherical XY ferromagnet with a random field in the boson space. We obtain a general expression of the critical temperat ure Tc below which the ordered ferromagnet phase appears. The Imry-Ma result concerning the lower critical dimension dc = 4 is recovered, and the critical exponents near the critical temperature Tc are calculated. We show that the random-field fluctuations rather than the quantum fluctuations dominate the phase transition and critical behavior of the system. The entropy vanishes as Td/2 at low temperatures, contrary to the classical spherical model. 相似文献
169.
170.
Masayuki Kumon 《Annals of the Institute of Statistical Mathematics》1992,44(2):239-260
The present paper treats the identification of parametric nonminimum phase transfer function. We propose a method of identification based on the inner outer factorization of stable transfer function. It consists of identifying the outer and inner parts of a transfer function separately. The outer part is identified by the use of the second-order spectral estimate from the observed linear process, while the inner part is identified by the use of a higher-order cumulant spectral estimate from the observed process. Respective parameter estimators are determined in the light of asymptotic efficiency. In order to estimate the order of the inner part of a transfer function, a criterion is proposed. It is introduced based on the same principle as in the case of Akaike's AIC. 相似文献