Dynamic optical correlation using localized holography

A new technique for optical correlation using gated holographic recording is demonstrated. Several persistent holograms are localized within separate slices as close as 33 microm apart along the crystal. Individual holograms can be dynamically erased and rerecorded with no need to refresh all other recorded holograms. Experimental results showing the correlation capability, cross talk, shift invariance, and dynamicity of the localized holographic correlator demonstrate unique performance and capabilities for these correlators.     

聚合物中长程关联能的动力学研究

本文计算采用扩展的SSH哈密顿模型,加上长程关联哈密顿量,在自然边界条件下,用绝热动力学方法研究了有限长反式聚乙炔链中平均关联能随时间的演化,计算了长程电子关联对极化子动力学的影响并计算了极化子状态下的长程关联能.结果发现,加入一个电子或空穴,平均关联能的大小随着时间呈非周期性阻尼振荡,经过一定时间后,平均关联能趋近一个恒定值,此时得到比较稳定的极化子位形.当格点增加时,长程关联能趋于恒定的时间逐渐缩短.     

Dynamic correlation in wave propagation in random media

Field spectra are analyzed to yield the time-resolved statistics of pulsed transmission through quasi-one-dimensional dielectric media with static disorder. The normalized intensity correlation function with displacement and polarization rotation for an incident pulse of linewidth sigma at delay time t is a function only of the field correlation function, which is identical to that found for steady-state excitation, and of kappa(sigma)(t), the residual degree of intensity correlation at points at which the field correlation function vanishes. The dynamic probability distribution of normalized intensity depends only upon kappa(sigma)(t). Steady-state statistics are recovered in the limit sigma-->0, in which kappa(sigma=0) is the steady-state degree of correlation.     

Path integral for equities: Dynamic correlation and empirical analysis

This paper develops a model to describe the unequal time correlation between rate of returns of different stocks. A non-trivial fourth order derivative Lagrangian is defined to provide an unequal time propagator, which can be fitted to the market data. A calibration algorithm is designed to find the empirical parameters for this model and different de-noising methods are used to capture the signals concealed in the rate of return. The detailed results of this Gaussian model show that the different stocks can have strong correlation and the empirical unequal time correlator can be described by the model’s propagator. This preliminary study provides a novel model for the correlator of different instruments at different times.     

Dynamic correlation function for the propagation of light in disordered medium

We have calculated the time autocorrelation function of the intensity of light multiply scattered in the medium with dynamical properties. A new asimptotic for larget is found.     

Dynamic correlation in magnetorheological composite under magnetic field studied by XPCS

The purpose of the research was to check dynamic correlations under magnetic field in the composite type magnetorheological material consisting of polyurethane gel with embedded carbonyl-iron (CI) micrometric spheres. The onion-like sphere structure of CI was destroyed during the composite processing. An X-ray photon correlation spectroscopy (XPCS) study of the composite was performed under magnetic field of 0, 300 and 600 mT. The following conclusions were obtained from the study: (i) The polyurethane matrix is preferred as a source of the observed dynamic effects. (ii) For 300 mT the material dynamics in direction of the outer magnetic field is very clear. (iii) For 600 mT the dependence of the dynamics on magnetic field direction disappears but correlation rate is much higher. This finding may be caused by a disturbance of the polymer mesostructure by larger strain leading to its reinforcement.     

Dynamic deformation image de-blurring and image processing for digital imaging correlation measurement

This paper proposes a method for de-blurring of images captured in the dynamic deformation of materials. De-blurring is achieved based on the dynamic-based approach, which is used to estimate the Point Spread Function (PSF) during the camera exposure window. The deconvolution process involving iterative matrix calculations of pixels, is then performed on the GPU to decrease the time cost. Compared to the Gauss method and the Lucy–Richardson method, it has the best result of the image restoration. The proposed method has been evaluated by using the Hopkinson bar loading system. In comparison to the blurry image, the proposed method has successfully restored the image. It is also demonstrated from image processing applications that the de-blurring method can improve the accuracy and the stability of the digital imaging correlation measurement.     

Dynamic structural correlations and Van Hove's correlation function for liquids

The stochastic model for liquids, developed previously and applied to the evaluation of static correlations, is extended to the evaluation of the dynamic pair correlation function. This extension can be achieved by a generalization of the width function W, characterizing the spread in the distribution of correlated local structures, from a piecewise linear function of r to a piecewise linear function in the (r, t) plane.     

Particle Sizing by Dynamic Light Scattering: Noise and distortion in correlation data

Two undesirable effects occur in particle sizing by dynamic light scattering; statistical noise, and distortion of correlation data. Statistical noise in the correlation data, caused by estimating the autocorrelation of scattered laser light by a time average, leads to non-physical artifacts in the resulting linewidth distribution. These may be removed by regularization, computer modeling, or other techniques. The regularized kernel function for inverting the Laplace transform is calculated, and used to illustrate the problem of noise. Correct choice of the regularization parameter gives the minimum overall error. It is found that excessive error occurs unless the linewidth distribution is modeled over a finite range. Analytical models for the linewidth with finite range, based on the beta distribution of probability theory, are given. Distortion of correlation data may occur in three ways, through a focused or otherwise nonuniform laser beam in the optical system, by insufficient bit resolution in the quantized detection of scattered laser light, or by calculating a first order field autocorrelation from a second order intensity autocorrelation. Unlike noise, distortion cannot be removed by any known methods, since the exact nature of the distortion is unknown. Several examples illustrate how distortion can lead to artifacts in the linewidth distribution which could easily be misinterpreted as segments of a size distribution, not present in the physical sample.     

Dynamic characteristics of an adaptive correlation autocompensator in the presence of nonstationary interference

Khar'kov Polytechnic Institute. Radioastronomy Institute, Academy of Sciences of the Ukrainian SSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 3, pp. 314–320, March, 1989.     

Finite correlation time effects in nonequilibrium phase transitions: I. Dynamic equation and steady state properties

We determine an approximate renormalized equation of evolution for an arbitrary nonlinear single-degree-of-freedom system externally driven by Gaussian parametric fluctuations of finite correlation time. The renormalization scheme used here gives a second order equation with a time-and-state-dependent “diffusion coefficient”. We are able to calculate the diffusion coefficient in closed form. The steady-state distribution can easily be obtained from the evolution equation. We are thus able to determine the parameter dependence of the steady-state distribution and, in particular, the influence of a correlation time of the fluctuations, which does not vanish, on the steady-state distribution.     

Two-particle correlation function and dihadron correlation approach

It is shown that, in the case of asymmetric nuclear interactions, the application of the traditional dihadron correlation approach to determining a two-particle correlation function C may lead to a form distorted in relation to the canonical pair correlation function _C². This result was obtained both by means of exact analytic calculations of correlation functions within a simple string model for proton–nucleus and deuteron–nucleus collisions and by means of Monte Carlo simulations based on employing the HIJING event generator. It is also shown that the method based on studying multiplicity correlations in two narrow observation windows separated in rapidity makes it possible to determine correctly the canonical pair correlation function C₂ for all cases, including the case where the rapidity distribution of product particles is not uniform.     

Non-zero total correlation means non-zero quantum correlation

We investigated the super quantum discord based on weak measurements. The super quantum discord is an extension of the standard quantum discord defined by projective measurements and also describes the quantumness of correlations. We provide some equivalent conditions for zero super quantum discord by using quantum discord, classical correlation and mutual information. In particular, we find that the super quantum discord is zero only for product states, which have zero mutual information. This result suggests that non-zero correlations can always be detected using the quantum correlation with weak measurements. As an example, we present the assisted state-discrimination method.     

Multifractional correlation

Multifractional correlation is proposed that is based on a new generalized fractional Fourier transform to which we refer as a multifractional Fourier transform. The multifractional correlation yields remarkable improvements in the correlation output peak intensity, peak sharpness, and light efficiency compared with convention correlation, which uses matched and phase-only filters, and still maintains better target discrimination capability and a reasonable robustness to noise. An optoelectronic hybrid system that can implement the multifractional correlation is also suggested.