Signal processing of double-beam and double-scattering laser Doppler velocimeter

The common method of laser Doppler velocimeter (LDV) signal processing is fast Fourier transform (FFT). Because of the restraint of spectral interference, fence effect and spectrum leakage, the precision of FFT is not high. In order to improve the accuracy of double-beam and double-scattering laser Doppler velocimeter signal processing, an algorithm based on spectral refinement and interpolation is put forward. First, high-pass filter is adopted to remove the baseplate of LDV signal. Second, FFT is adopted to get the estimate of Doppler frequency and then Zoom-FFT is used to refine the local range of Doppler frequency. Third, four-term fifth derivative Nuttall windowed interpolation is used to correct the refined spectrum. Then the accurate estimate of Doppler frequency can be obtained. Simulations and experiments based on the LDV system built in laboratory show that Zoom-FFT can improve the resolution of spectrum and four-term fifth derivative Nuttall windowed interpolation can further increase the precision of signal processing.     

Fourier Interferometry as Applied to Microspectrofluorometry and Fluorescence Imaging of Living Cells

Excitation-emission fluorescence spectroscopy and imaging are applied to studies of cellular metabolism and at the convergence of cellular differentiation, detoxification, transformation, and senescence. Metabolic activity, intracellular redox levels, and compartmentation are probed by coenzyme [NAD(P)H] transients and monochlorobimane for glutathione dehydrogenase. Gene expression or its failure in lysosomal disorders is identified with fluorogenic probes. The "multiorganelle detoxification complex" is visualized and investigated with cytotoxic agents. A kind of photoactivated "accelerated cellular senescence" is recognized by accumulation of Schiff bases. Conventional and novel mitochondrial probes are used to localize these organelles in Saccharomyces cerevisiae as a model for future studies in mammalian cells and to detect in these very cells the organelle interactions resulting from the action of mitochondria-toxic drugs. The potential of these studies for biotechnology and instrumentation relying on fibers and integrated optics is considerably enhanced by Fourier interferometry.     

Stilbene composite scintillators as detectors of fast neutrons emitted by a 252Cf source

The results of the measurements are presented of the relative efficiency ε for ²⁵²Cf fast neutron detection by composite detectors based on stilbene crystalline grains. The effects of the grain size and height of the composite detector on its scintillation properties were studied. It is shown that the efficiency of fast neutron detection of stilbene composite scintillators ranges up to 60% of that of bulk single crystals. The results are also presented for relative light output measurements of stilbene composite detectors irradiated by gamma photons of ¹³⁷Cs, as well as transmittance data of samples in the range of their transparency absorption.     

Convergence for Summation Methods with Multipliers on the Sphere

In this article, we present convergence rates for summation methods with multipliers related to certain approximation methods on the sphere we previously introduced and discussed in Menegatto and Piantella [13 V.A. Menegatto and A.C. Piantella ( 2005 ). Approximation on the sphere by weighted Fourier expansions . J. Appl. Math. 2005 ( 4 ): 321 – 340 . [Google Scholar]]. The results are based upon spherical moduli of smoothness defined via the Laplace–Beltrami derivative.     

电各向异性色散介质电磁散射时域有限差分分析的半解析递推卷积方法

利用坐标系转换矩阵给出实验室系中磁化等离子体介质的频域极化率张量, 采用部分分式展开方法通过傅里叶逆变换得到极化率张量的时域指数函数形式, 应用数字信号处理中的半解析递归卷积算法, 给出适用于处理任意外磁场方向情形下磁化等离子体目标电磁散射的半解析递归卷积-时域有限差分计算方法. 计算了磁化等离子体球的同极化和交叉极化后向雷达散射截面, 结果表明了算法的正确有效性. 关键词： 半解析递归卷积 磁化等离子体 电磁散射 时域有限差分方法     

沿着某个方向凸的调和单叶映射的构造

本文给出调和单叶映射的凸组合和卷积单叶且沿着某个方向凸的若干充分条件,部分解决Dorf所提出的一个公开问题,相关结果推广和改进早期的一些结论.最后,通过三个例子验证所得到的主要结果.     

High-Temperature Liquid Chromatography

Abstract

The influence of temperature on separation is discussed. Elevated temperature can significantly reduce the retention times in liquid chromatography and thus the throughput and running costs of a LC instrument. A decrease of viscosity at increasing temperatures allows the use of columns packed with very small particles and of higher flow rates as well. Modern reversed phase columns are stable up to (and >) 90°C. Metal oxide columns (Zirconium oxide, Titanium dioxide, Aluminium oxide) and polymer packed columns are temperature stable up to 200°C. The consumption of organic solvents can significantly be reduced and thus also the disposal costs.     

块Toeplitz方程组的快速块Gauss-Seidel迭代算法

本文研究块Toeplitz方程组的块Gauss-Seidel迭代算法。我们首先讨论了块三角Toeplitz矩阵的一些性质,然后给出了求解块三角Toeplitz矩阵逆的快速算法,由此而得到了求解块Toeplitz方程组的快速块Gauss-Seidel迭代算法,最后证明了当系数矩阵为对称正定和H-矩阵时该方法都收敛,数值例子验证了方法的收敛性。     

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介绍了离子回旋波加热领域研究进展,具体分析了快波少子加热模式转换情况以及影响模式转换分量大小和位置的因素。通过控制波的频率及少子浓度,使得波能够顺利传播到托卡马克等离子体的离子混合共振与截止的区域附近,并转换为离子Bernstein波而被等离子体有效吸收,因而能够改善加热效果。