Experimental Study on Particle Size Distribution and Concentration Using Transmission Fluctuation Spectrometry with the Autocorrelation Technique

Based on the statistical characteristics of the transmission fluctuations in the particle suspension, transmission fluctuation spectrometry with autocorrelation (TFS‐AC) is described theoretically, with the assumptions of geometric ray propagation and completely absorbent particles in the suspension. The experiments presented here are realized in a focused Gaussian beam with the TFS‐AC technique. The acquisition of transmission fluctuation signals is achieved by using a high‐resolution digital oscilloscope. The transition function of TFS‐AC is obtained by varying the autocorrelation time. With a modified iterative Chahine inversion algorithm, solving a linear equation retrieves information on the particle size distribution and particle concentration. Some experimental results on spherical and non‐spherical particles are presented and discussed. The experiments cover a particle size range from 1μm to 1000 μm and a particle concentration of up to 12 %.     

Two-tuple balance of non-binary sequences with ideal two-level autocorrelation

Let p be a prime, q=p^m and F_q be the finite field with q elements. In this paper, we will consider q-ary sequences of period qⁿ-1 for q>2 and study their various balance properties: symbol-balance, difference-balance, and two-tuple-balance properties. The array structure of the sequences is introduced, and various implications between these balance properties and the array structure are proved. Specifically, we prove that if a q-ary sequence of period qⁿ-1 is difference-balanced and has the “cyclic” array structure then it is two-tuple-balanced. We conjecture that a difference-balanced q-ary sequence of period qⁿ-1 must have the cyclic array structure. The conjecture is confirmed with respect to all of the known q-ary sequences which are difference-balanced, in particular, which have the ideal two-level autocorrelation function when q=p.     

Instability and violence in Imperial Rome: A “laboratory” for studying social contagion?

Imperial Rome with its >50% assassination rate of emperors, many of whom are depicted in history as ‘deranged’, initially appears a chaotic period of history beyond the purview of science. But time series analysis indicates this violence occurred non‐randomly: reign length was autocorrelated and demonstrated ‘memory persistence,’ and short reigns occurred in clusters. Additionally, deviations from average reign‐length occurred in patterns matching the Empire's rise and decline. A model is proposed for how army‐backed usurpation and post‐coup instability likely generated the observed cycles. The five‐century span of Imperial Rome likely makes it the longest‐lived regime with fair documentation, and potentially provides a ‘laboratory’ with ongoing relevance for studying transmission of violence and instability. © 2016 Wiley Periodicals, Inc. Complexity 21: 613–622, 2016     

H-在金属面附近光剥离的波包动力学研究

利用波包演化和自关联函数方法对H^-在金属面附近光剥离的波包动力学进行了研究.结果表明,金属面附近光剥离电子的波包演化和回归结构与H^-到金属面的距离、激光脉冲的脉冲宽度和初始动量都有一定的关系.因此,可以通过改变离子表面距离和激光脉冲的参数对光剥离电子的动力学性质进行调控研究.除此之外,光剥离电子的镜像态寿命对波包的演化和自关联函数也会产生一定的影响:考虑镜像态寿命的影响时,随着时间的演化,波包概率密度的振幅逐渐减小,波包整体上有明显的衰减,寿命对波包演化过程中的干涉有削弱的作用;通过对电子波包的自关联函数研究,发现无限长寿命的电子波包有很好的量子回归现象,而当考虑寿命因素后光剥离电子波包随着时间的演化会发生周期性的坍塌和扩散,经过一段时间后,该回归现象消失.本文的理论研究可以为表面附近电子波包动力学的实验研究提供一定的参考价值. 关键词： 波包 演化和回归 自关联函数 金属面     

Computer simulation of trifluoromethane properties with ab initio force field

Intermolecular interaction potentials of the trifluoromethane dimer in 15 orientations have been calculated using the Hartree‐Fock (HF) self‐consistent theory and the second‐order Møller‐Plesset (MP2) perturbation theory. Single point energies at important geometries were also calibrated by the coupled cluster with single and double and perturbative triple excitation [CCSD(T)] calculations. We have employed Pople's medium size basis sets [up to 6‐311++G(3df,3pd)] and Dunning's correlation consistent basis sets (up to aug‐cc‐pVQZ). Basis set limit potential values were obtained through well‐studied extrapolation methods. The calculated MP2 potential data were employed to parameterize a 5‐site force field for molecular simulations. We performed molecular dynamics simulations using the constructed ab initio force field and compared the simulation results with experiments. Quantitative agreements for the atom‐wise radial distribution functions and the self‐diffusion coefficients over a wide range of experimental conditions can be obtained, thus validating the ab initio force field without using experimental data a priori. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Conservation of the particle-hole symmetry in the pseudogap state in optimally-doped Bi2Sr2CuO6+δ superconductor

The pseudogap state is one of the most enigmatic characteristics in the anomalous normal state properties of the high temperature cuprate superconductors. A central issue is to reveal whether there is a symmetry breaking and which symmetries are broken across the pseudogap transition. By performing high resolution laser-based angle-resolved photoemission measurements on the optimally-doped Bi₂Sr_1.6La_0.4CuO_6+δ superconductor, we report the observations of the particle-hole symmetry conservation in both the superconducting state and the pseudogap state along the entire Fermi surface. These results provide key insights in understanding the nature of the pseudogap and its relation with high temperature superconductivity.     

基于改进时空Moran's I指数的道路交通状态特征分析

定义时空对象代替空间对象作为基本研究单元, 改进传统Moran's I指数为时空Moran's I指数, 以便适于分析道路交通的时空特性; 通过Moran散点图给出时空自相关意义下的交通流时空状态特征分类: 拥堵聚集、畅通聚集、拥堵异质和畅通异质.为说明改进时空Moran's I指数分析法的实际应用价值, 以北京市二环快速路外环方向的车流速度数据为例, 进行时空自相关指标计算, 并从全局与局部自相关两个方面分析时 空自相关指标所反映的交通状态时空分布与演化规律. 关键词： I指数')" href="#">改进Moran's I指数 交通状态 时空自相关 时空分布     

Fractional time-varying energy distributions of ECG signals

We introduce here fractional Cohen class of time-frequency distributions (FCCTFDs) containing fractional modulations which is kernel of fractional Fourier transform (FFT). The fractional modulation depends on angular parameter α and can be interpreted as a rotation by an angle α in time-frequency plane. This distribution promotes to track time-variant energy of a biological signals and represents it in time-frequency domain. It uses the fractional ambiguity function (FAF) of signal multiplied by a suitable kernel which is designed for the biological signals generally having multi-non-stationary components. This result improves and generalizes some of the previous time-frequency distributions derived in the literature.     

Using Spatial Statistics to Select Model Complexity

Testing for nonindependence among the residuals from a regression or time series model is a common approach to evaluating the adequacy of a fitted model. This idea underlies the familiar Durbin–Watson statistic, and previous works illustrate how the spatial autocorrelation among residuals can be used to test a candidate linear model. We propose here that a version of Moran's I statistic for spatial autocorrelation, applied to residuals from a fitted model, is a practical general tool for selecting model complexity under the assumption of iid additive errors. The “space” is defined by the independent variables, and the presence of significant spatial autocorrelation in residuals is evidence that a more complex model is needed to capture all of the structure in the data. An advantage of this approach is its generality, which results from the fact that no properties of the fitted model are used other than consistency. The problem of smoothing parameter selection in nonparametric regression is used to illustrate the performance of model selection based on residual spatial autocorrelation (RSA). In simulation trials comparing RSA with established selection criteria based on minimizing mean square prediction error, smooths selected by RSA exhibit fewer spurious features such as minima and maxima. In some cases, at higher noise levels, RSA smooths achieved a lower average mean square error than smooths selected by GCV. We also briefly describe a possible modification of the method for non-iid errors having short-range correlations, for example, time-series errors or spatial data. Some other potential applications are suggested, including variable selection in regression models.