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91.
Jiangfeng Luan 《Optik》2011,122(2):168-172
The temporal intensity distributions of the transmitted light through the tissue with lesion structures are investigated using the polarized Monte Carlo technique. Simulation results show that time-resolved curves of transmitted light change obviously for different lesion structures. When the lesion thickness increases, the intensity of transmitted light decreases for co-polarization detection and increases for cross-polarization detection. With the increase of the lesion depth, the amplitude rises for both co- and cross-polarization detection. A method considering the dependence of the peak temporal distribution on the lesion position is thus proposed to locate lesions inside live tissues. 相似文献
92.
Chen Rong Kazuya Mitsuji Xue Songtao Yoshihiro Sugimura Masanori Izumi 《Acta Mechanica Solida Sinica》1999,12(2):144-154
The purpose of this paper is to study the dynamic behavior of soft ground including a porous layer by considering the porosity
change. In order to take the porosity change into account, the concept of the volume fraction, which has been proposed in
continuum mechanics, is introduced. The constitutive equations presented by Bowen are applied to the analysis of the porous
media. According to Bowen's theory, the porosity is considered as a variable called the volume fraction and has its own constitutive
equation. The constitutive equation of the volume fraction has thermoelastic equation coefficients and is determined by the
strains of the solid and the fluid. This means that the compressibilities of the solid and the fluid are considered. When
the special condition is assumed, Bowen's theory can contain Biots's theory, which has been applied in earthquake engineering.
The wave propagation in the ground including a porous layer, modeled by Bowen's theory, is studied and compared with that
of Biot's theory. One-dimensional attenuation and surface amplitude are calculated. The effect of the volume fraction is discussed
with respect to the compressibilities of the solid and the fluid. 相似文献
93.
Haydar Aygün Keith Attenborough Walter Lauriks Philip A. Rubini Christian M. Langton 《Applied Acoustics》2011,(7):458-463
Comparisons between predictions of a Biot-Allard model allowing for angle-dependent elasticity and angle-and-porosity dependent tortuosity and transmission data obtained at normal incidence on water-saturated replica bones are extended to oblique incidence. The model includes two parameters which are adjusted for best fit at normal incidence. Using the same parameter values, it is found that predictions of the variation of transmitted waveforms with angle through two types of bone replica are in reasonable agreement with data despite the fact that scattering is not included in the theory. 相似文献
94.
Numerical dispersion of two-dimensional finite elements was studied. The outcome of the dispersion study was verified by the numerical and analytical solutions to the longitudinal impact of two long cylindrical bars. In accordance with the results of the dispersion analysis it was demonstrated that the quadratic elements showed better accuracy than the linear ones. 相似文献
95.
P. Sigmund 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):111-116
Second-harmonic cross-correlation operates a selection in time-phase among the randomly de-phased contributions to an optical
field that propagated through a scattering medium. It can thus be used to selectively detect the weak contribution remaining
coherent with the incident field.
Received 7 May 1999 相似文献
96.
O Introduction
We consider the orbital instability of standing waves for the Klein-Gordon-Zakharov system with different propagation speeds in three space dimensions 相似文献
97.
Summary It is shown how to deduce in a straightforward way the class of transcendental functions which appear in the elements of the
dielectric tensor of a weakly relativistic thermal plasma. The deduction is made directly from the second form of Trubnikov
integrals and is valid for arbitrarily large values of the wave perpendicular refractive index.
Riassunto Si mostra come sia possibile dedurre in modo molto diretto la famiglia di trascendenti che appare negli elementi della matrice dielettrica di un plasma debolmente relativistico in condizioni di equilibrio termico. Il procedimento parte direttamente dalla così detta seconda forma degli integrali di Trubnikov ed è valido per valori arbitrariamente grandi dell’indice di rifrazione perpendicolare al campo magnetico nel quale è immerso il plasma.
Резюме Мы показываем, как вывести непосредственным образом класс трансцендентных функций, которые появляются в элементах диэлектрического тензора для слабо релятивистской плазмы в условиях теплового равновесия. Вывод проводится непосредственно из второй формы интегралов Трубникова и справедлив для произвольно больших величин показателя преломления для волны, перпендикулярной магнитному полю, в которое помещена плазма.相似文献
98.
B. Jourdain 《Methodology and Computing in Applied Probability》2000,2(1):69-91
In this paper, we explain how to associate a nonlinear martingale problem with some nonlinear parabolic evolution equations starting at bounded signed measures. Our approach generalizes the classical link made when the initial condition is a probability measure. It consists in giving to each sample-path a signed weight which depends on the initial position. After dealing with the classical McKean-Vlasov equation as an introductory example, we are interested in a viscous scalar conservation law. We prove uniqueness for the corresponding nonlinear martingale problem and then obtain existence thanks to a propagation of chaos result for a system of weakly interacting diffusion processes. Last, we study the behavior of the associated fluctuations and present numerical results which confirm the theoretical rate of convergence. 相似文献
99.
100.
Alessandro Antonucci Yi Sun Marco Zaffalon 《International Journal of Approximate Reasoning》2010,51(5):474-484
Credal networks generalize Bayesian networks by relaxing the requirement of precision of probabilities. Credal networks are considerably more expressive than Bayesian networks, but this makes belief updating NP-hard even on polytrees. We develop a new efficient algorithm for approximate belief updating in credal networks. The algorithm is based on an important representation result we prove for general credal networks: that any credal network can be equivalently reformulated as a credal network with binary variables; moreover, the transformation, which is considerably more complex than in the Bayesian case, can be implemented in polynomial time. The equivalent binary credal network is then updated by L2U, a loopy approximate algorithm for binary credal networks. Overall, we generalize L2U to non-binary credal networks, obtaining a scalable algorithm for the general case, which is approximate only because of its loopy nature. The accuracy of the inferences with respect to other state-of-the-art algorithms is evaluated by extensive numerical tests. 相似文献