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931.
噪音对光学图象浑沌相位列阵加密和解密的影响 总被引:1,自引:0,他引:1
本文提出了一种用浑沌相位列阵对光学图象加密和解密的方法,并重点分析了加法高斯白噪音对光学图象浑沌相位列阵加密和解密的影响.通过计算机模拟发现加密后的图象与原图象相比,抗振幅噪音的能力增强,而抗相位噪音的能力下降.在一定信噪比范围内,相位噪音是影响解密图象质量的主要因素. 相似文献
932.
Electron-beam-induced current (EBIC) and secondary electron image (SEI) modes of a scanning electron microscope (SEM) are
utilized for characterization of charge collection inhomogeneities in hydrogenated amorphous silicon devices. These inhomogeneities
are due to such fabrication defects as substrate surface roughness, pin holes, blistering and lift-off. SEM observations are
correlated with the electrical properties of the devices. Electronirradiation-induced damage in these devices is also investigated
by measuring the EBIC time decay at continuous electron irradiation as a function of both the electron -beam energy and current.
This decay mechanism is based on the formation of electron-irradiation-induced microscopic defects that act as recombination
centers and reduce the lifetime of carriers. 相似文献
933.
对冲击电流计测直螺线管磁场的两项改进措施 总被引:2,自引:0,他引:2
通过一些具体数据,对冲击电流计测直螺线管磁场的实验进行了分析,指出了两个重要误差来源,并介绍了改进措施。 相似文献
934.
用二维气体激光模型对量子噪声的实部和虚部存在耦合的激光场进行了理论分析,通过福克-普朗克方程导出了定态激光光场强度和位相的分布函数,算出了定态激光强度和位相的平均值,方差和偏斜度,与量子噪声的两个分量为独立随机变量的激光场相比,噪声间的耦合极大地改变了激光场强度和位相的涨落,并引起了激光场强度与位相之间的耦合。 相似文献
935.
The ideally simple situation of a single 180° Bloch wall in a single crystal already involves rather complex physical mechanisms. For a given variation of the magnetic field, two types of irreversible motion of the wall can be observed, depending on the velocity imposed to the wall and the temperature. It can move like a rigid plane, then its irreversible displacements are always larger than its thikness. It can also move by localized, small jumps thanks to its internal degrees of freedom. The features of the Barkhausen noise are different in these two kinds of motion. The transition between them occurs either at a constant temperature by increasing the velocity of the wall, or at a constant velocity by lowering the temperature. The wall can also move under the effect of thermal fluctuation, which should not be regarded as some little perturbation, but rather as an essential physical parameter which has to be taken into account in any realistic model of wall motion, and hence of “Barkhausen noise”. The random character of these phenomena allowed us to employ simple, but very useful, statistical methods. Besides, this study suggests some specific problems of “signal processing”. 相似文献
936.
In the last paper, the geometry of the Sz.-Nagy-Foia
model for contraction operators on Hilbert spaces was used to advantage in several problems of multivariate analysis. The lifting of intertwining operators, one of the basic results from the Sz.-Nagy-Foia
theory, is now recognized as the most adequate operatorial form of the deep classical results of the extrapolation theory. The labeling of the exact intertwining dilations given by [1]Acta Sci. Math. (Szeged) 40 9–32] and the recursive methods used there open a broad perspective for using the Sz.-Nagy-Foia
model in multivariate filtering theory. In this paper, using the notion of correlated action (see [5 and 6] Rev. Roumaine Math. Pures Appl. 23, No. 9 1393–1423]) as a time domain, a linear filtering problem is formulated and its solution in terms of the coefficients of the analytic function which factorizes the spectral distribution of the known data and the coefficients of an analytic function which describes the cross correlations is given. In some special cases it is shown that the filter coefficients can be determined using recursive methods from the intertwining dilation theory, of the autocorrelation function of the known data and an intertwining operator, interpreted as the initial estimator given by the prior statistics. 相似文献
937.
An auto-ranging circuit which accommodates the erratic nature of the electrometer output signals from a spark-source mass-spectrometer is described briefly. 相似文献
938.
939.
Michael Scheutzow 《Stochastic Processes and their Applications》1985,20(2):323-331
It is shown that unlike nondegenerate (linear) diffusion processes, nonlinear diffusion processes can have a periodic law. We provide an example of a nonlinear diffusion for which periodic behavior is even created by the noise, i.e. no periodicity occurs when the noise is turned off. In the second part of the paper we give an example of a one-dimensional nonlinear diffusion which can be stabilized by noise. Finally we show also that the N-dimensional (N ≥ 2) ‘linear’ diffusion approximations of that system are stabilized by noise. 相似文献
940.
Hao?CaiEmail author Feng-Ming?Liu Nian-Ning?Huang 《International Journal of Theoretical Physics》2005,44(2):255-265
The inverse scattering transform for the nonlinear Schrödinger equation in normal dispersion with non-vanishing boundary values is re-examined using an affine parameter to avoid double-valued functions. An operable algebraic procedure is developed to evaluate dark multi-soliton solutions. The dark two-soliton solution is given explicitly as an example, and is verified by direct substitution. The additional motion of the soliton center is given by its asymptotic behavior. 相似文献