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981.
982.
This work is concerned mainly with developing and testing the reduced-order extrapolated approach to the unknown coefficient vectors in the Crank-Nicolson finite element (CNFE) solutions for the uniform transmission line equation. For this objective, the CNFE functional and matrix models and the existence, stability, and errors of the CNFE solutions of the uniform transmission line equation are first derived. Then a reduced-order extrapolated CNFE (ROECNFE) matrix model is established by means of a proper orthogonal decomposition technique, and the existence, stability, and error estimates of the ROECNFE solutions are demonstrated by matrix analysis, leading to an elegant theoretical development. Especially, our work shows that the basis functions and accuracy of the ROECNFE matrix model are the same as those of the CNFE matrix model. Finally, some numerical tests are illustrated to computationally experimentally confirm the validity and sharpness of the ROECNFE method. 相似文献
983.
为了解决高速CCD成像电路串扰问题,分析了产生串扰的原因,建立了CCD成像电路的串扰模型,提出了有效的抗串扰技术。对多通道的CCD视频信号采用带状线而非微带线并使用防护布线进行隔离。对多通道的电源供电进行了隔离,设计并采取有效的去耦电容布线方法,降低了寄生电感,避免了由电源公共阻抗引起的串扰。采用统一的地平面,对模拟电路和数字电路进行分区布局,避免了地弹对信号的影响。针对一个串扰较严重的CCD成像电路进行了实验,结果表明:采取上述抗串扰技术后,通道隔离度大于60 dB,有效降低了串扰,提高了图像质量。 相似文献
984.
介绍了材料复介电常数测量方法的研究进展,包括理论基础,发展过程,以及最新的应用.其中主要以谐振法,传输反射法,自由空间法为研究对象,就各类方法的优缺点与适用情况进行分析,也简要介绍了时域测量法. 相似文献
985.
986.
987.
Anthony B. Davis Mark B. Mineev-Weinstein 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(4):632-645
We survey research on radiation propagation or ballistic particle motion through media with randomly variable material density, and we investigate the topic with an emphasis on very high spatial frequencies. Our new results are based on a specific variability model consisting of a zero-mean Gaussian scaling noise riding on a constant value that is large enough with respect to the amplitude of the noise to yield overwhelmingly non-negative density. We first generalize known results about sub-exponential transmission from regular functions, which are almost everywhere continuous, to merely “measurable” ones, which are almost everywhere discontinuous (akin to statistically stationary noises), with positively correlated fluctuations. We then use the generalized measure-theoretic formulation to address negatively correlated stochastic media without leaving the framework of conventional (continuum-limit) transport theory. We thus resolve a controversy about recent claims that only discrete-point process approaches can accommodate negative correlations, i.e., anti-clustering of the material particles. We obtain in this case the predicted super-exponential behavior, but it is rather weak. Physically, and much like the alternative discrete-point process approach, the new model applies most naturally to scales commensurate with the inter-particle distance in the material, i.e., when the notion of particle density breaks down due to Poissonian—or maybe not-so-Poissonian—number-count fluctuations occur in the sample volume. At the same time, the noisy structure must prevail up to scales commensurate with the mean-free-path to be of practical significance. Possible applications are discussed. 相似文献
988.
In this paper we numerically investigate the nonlinear propagation of defect state in one-dimensional structures with defects. We investigate the nonlinear transmission spectra and the bistable response for defective structures with different index gradients. The results show that positive Kerr nonlinearity can suppress the Wannier-Stark localization. And the nonlinear response of defect states band exhibits an optical switch behavior, which may be applied to all-optical devices. And the gap solitons from these defect states are presented. 相似文献
989.
A.A. Guda N. Smolentsev J. Verbeeck Y. Zubavichus O.E. Polozhentsev 《Solid State Communications》2011,151(19):1314-1317
ZnO/ZnO:Mn core-shell nanowires were studied by means of X-ray absorption spectroscopy of the Mn K- and L2,3-edges and electron energy loss spectroscopy of the O K-edge. The combination of conventional X-ray and nanofocused electron spectroscopies together with advanced theoretical analysis turned out to be fruitful for the clear identification of the Mn phase in the volume of the core-shell structures. Theoretical simulations of spectra, performed using the full-potential linear augmented plane wave approach, confirm that the shell of the nanowires, grown by the pulsed laser deposition method, is a real dilute magnetic semiconductor with Mn2+ atoms at the Zn sites, while the core is pure ZnO. 相似文献
990.
We report on the near‐edge X‐ray absorption fine structure spectroscopy of the L3 (2p3/2) and L2 (2p1/2) edges for ferromagnetic pure nickel transition metal and show that the L2,3 edge peak intensity and satellite feature at ~6 eV above the L3 edge in nickel increase with increasing nickel film thickness both in the total electron yield and transmission modes. The absorption spectra of nickel metal, however, exhibit strong angular‐dependent effects when measured in total electron yield mode. In addition, we calculated the mean electron escape depth of the emitted electrons (λe), which was found for pure nickel metal to be λe=25 ± 2 Å. We point out the advantages of the total electron yield technique for the study of the L‐edge of 3d transition metals. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献