Amplitude Correlation Coefficient Research Articles

High degree of chaos synchronization in pairs of transverse modes with parity-symmetric polarizations in a thin-slice solid-state vector laser and application to polarimetric secure self-mixing metrology.

A high degree of chaos synchronization among transverse mode pairs with parity-symmetric polarizations was demonstrated in a laser-diode pumped thin-slice c-cut Nd:GdVO4 laser. The amplitude correlation coefficient greater than R>0.994 resulted from a non-reversing mirror symmetric-polarization-dependent structural change in the modal patterns, where chaotic dynamics of the whole system consisting of qualitatively different dynamics, which depend on the polarization crossing angle, resembled that of a chaotic single mode laser. A self-organized sender-receiver type of chaos synchronization of a single pair of modes among an infinite number of parity-symmetric polarizations, the associated chaotic camouflaging, and the extracting experiment of a self-mixing solid-state laser Doppler velocimetry signal were demonstrated.

Dynamic characterization of beating sinusoidal wave oscillations in a thin-slice solid-state laser with coupled orthogonally polarized transverse modes

Dynamic characterization of self-induced beating sinusoidal wave (BSW) oscillations and related phenomena, which were previously explored in a thin-slice dual-polarization solid-state laser operating in the regime of incomplete mode-locking of orthogonally polarized transverse eigenmodes, namely, a quasi-locked state Otsuka (2018 Laser Phys. Lett. 15 075001), is performed in terms of the amplitude correlation coefficient and intensity circulation among various orthogonally polarized mode pairs. Polarization-dependent symmetry-breaking featuring a nonreciprocal intensity flow for different orthogonally polarized mode pairs operating in the BSW state are found. The singular state is hidden in a nonlinear system where a perfect mode-locked BSW state with a large amplitude correlation coefficient featuring reciprocal intensity flow is established for a transverse mode pair possessing particular polarization directions that are related to the intensity ratio of orthogonally polarized transverse eigenmodes. Self-organized chaos synchronization is shown to take place for such a single pair of transverse modes subjected to self-mixing modulations.

Dynamic characterization of beating sinusoidal wave oscillations in a thin-slice solid-state laser with coupled orthogonally polarized transverse modes

Dynamic characterization of self-induced beating sinusoidal wave (BSW) oscillations and related phenomena, which were previously explored in a thin-slice dual-polarization solid-state laser operating in the regime of incomplete mode-locking of orthogonally polarized transverse eigenmodes, namely, a quasi-locked state Otsuka (2018 Laser Phys. Lett. 15 075001), is performed in terms of the amplitude correlation coefficient and intensity circulation among various orthogonally polarized mode pairs. Polarization-dependent symmetry-breaking featuring a nonreciprocal intensity flow for different orthogonally polarized mode pairs operating in the BSW state are found. The singular state is hidden in a nonlinear system where a perfect mode-locked BSW state with a large amplitude correlation coefficient featuring reciprocal intensity flow is established for a transverse mode pair possessing particular polarization directions that are related to the intensity ratio of orthogonally polarized transverse eigenmodes. Self-organized chaos synchronization is shown to take place for such a single pair of transverse modes subjected to self-mixing modulations.

Amplitude and phase synchronization of European business cycles: a wavelet approach

AbstractIn the paper we suggest the use of amplitude correlation coefficients (ACCs) and phase-locking values (PLVs) in examining business cycle synchronization. The quantities are calculated on the basis of instantaneous amplitudes and phase differences, which are computed here with the help of the non-decimated discrete analytic wavelet transform. We show that the coefficients constitute an interesting add-in to the statistical apparatus of examining business cycle synchronization. The PLVs correct the information provided by the coherency and correlation coefficients for the influence of amplitude changes and are of use in examining phase synchronization of business cycles, which is important in forecasting the effectiveness of a common monetary policy. By contrast, the ACCs are based solely on amplitude information and have the interpretation of phase-adjusted correlation coefficients, which can be used to evaluate stabilization policies or to forecast these policies’ effectiveness. The methodology is applied to examine cyclical synchronization of 20 European Union (EU) countries. We show, among other things, that during the run-up to the euro both amplitude and phase synchronization increased, with the former tending to change more rapidly. Furthermore, for the new EU members an EU effect is identified in both types of cyclical synchronization with the euro area.

A correlation analysis and invariant method of acoustic-emission signals in the diagnostics of predestruction states of materials

The results of the application of correlation analysis and invariant method of acoustic-emission (AE) signals during the mechanical loading of 95X18 steel samples are considered. The circuit of a controller that is intended for calculation of statistical characteristics of AE signals is given. A method for diagnostics of predestruction states based on the appearance of stably positive values of the amplitude-correlation coefficient and AE pulse-repetition intervals and deviations of invariant AE relationships from their stable values is proposed.

Heterogeneity and independency of unitary synaptic outputs from hippocampal CA3 pyramidal cells

The variation of individual synaptic transmission impacts the dynamics of complex neural circuits. We performed whole-cell recordings from monosynaptically connected hippocampal neurons in rat organotypic slice cultures using a synapse mapping method. The amplitude of unitary excitatory postsynaptic current (uEPSC) varied from trial to trial and was independent of the physical distance between cell pairs. To investigate the source of the transmission variability, we obtained patch-clamp recordings from intact axons. Axonal action potentials (APs) were reliably transmitted throughout the axonal arbour and showed modest changes in width. In contrast, calcium imaging from presynaptic boutons revealed that the amplitude of AP-evoked calcium transients exhibited large variations both among different boutons at a given trial and among trials in a given bouton. These results suggest that a factor contributing to the uEPSC fluctuations is the variability in calcium dynamics at presynaptic terminals. Finally, we acquired triple whole-cell recordings from divergent circuit motifs with one presynaptic neuron projecting to two postsynaptic neurons. Consistent with the independency of calcium dynamics among axonal boutons, a series of uEPSC fluctuations was not correlated between the two postsynaptic cells, indicating that different synapses even from the same neuron act independently.We conclude that the intra-bouton and inter-bouton variability in AP-induced calcium dynamics determine the heterogeneity and independency of uEPSCs.

On the Channel and Signal Cross Correlation of Downlink and Uplink Mobile UHF DTV Channels With Antenna Diversity

UHF TV channels are traditionally used for television broadcasting where the channels can be regarded static or slowly-varying. Due to the transition from the analog television to the digital television, the UHF TV channels 52-69 will be reallocated to other applications and there is a need of re-evaluation of these channels under the new operational environments, e.g. mobile downlink and uplink channels with antenna arrays at the transmitter and the receiver. In this paper, new results on the temporal and spatial characteristics of the wideband UHF mobile wireless signals and channels in the Digital Television (DTV) broadcasting UHF frequency bands are presented. Our analysis of DTV mobile field measurements confirms that the complex channel correlation amplitude depends on the channel phase correlation and differs considerably from the channel envelope correlation. Furthermore, the autocorrelation of the ATSC DTV transmitted signal, embedded in our received signals, degrades the received signal amplitude correlation coefficients, in comparison with the channel envelope correlation coefficients, and increases the complex received signal correlation coefficients, in comparison with the complex channel correlation coefficients, in highly correlated channels. Both downlink and uplink DTV mobile broadcast channels are investigated. The field measurement results also show that the channel envelopes are highly correlated while the channel phases are uncorrelated. This may lead to the advent of a space time code or a modulation scheme that utilizes the phase information in order to maximize the channel capacity. The results exposed in this paper are important for designers of new mobile wireless systems in order to build new wireless applications, modulation schemes, equalizers and channel-tracking algorithms in the UHF TV spectrum.

Parameters estimation of sandwich beam model with rigid polyurethane foam core

In this work, the physical parameters of sandwich beams made with the association of hot-rolled steel, Polyurethane rigid foam and High Impact Polystyrene, used for the assembly of household refrigerators and food freezers are estimated using measured and numeric frequency response functions (FRFs). The mathematical models are obtained using the finite element method (FEM) and the Timoshenko beam theory. The physical parameters are estimated using the amplitude correlation coefficient and genetic algorithm (GA). The experimental data are obtained using the impact hammer and four accelerometers displaced along the sample (cantilevered beam). The parameters estimated are Young's modulus and the loss factor of the Polyurethane rigid foam and the High Impact Polystyrene.

The 5-GHz Airport Surface Area Channel—Part I: Measurement and Modeling Results for Large Airports

We describe results from a channel measurement and modeling campaign for the airport surface environment in the 5-GHz band. Using a 50-MHz bandwidth test signal, thousands of power delay profiles (PDPs) were obtained and processed to develop empirical tapped-delay line statistical channel models for large airports. A log-distance path loss model was also developed. The large airport surface channel is classified into three propagation regions, and models are presented for each of the regions for two values of bandwidth. Values of the median root-mean-square (RMS) delay spread range from 500 to 1000 ns for these airports, with the 90 th percentile RMS delay spreads being approximately 1.7 ms. Corresponding correlation bandwidths (i.e., correlation value 1/2) range from approximately 1.5 MHz in non-line-of-sight (NLOS) settings to 17.5 MHz in line-of-sight (LOS) settings. Two types of statistical nonstationarity were also observed: 1) multipath component persistence and 2) propagation region transitions. We provide the multipath component probability of occurrence models and describe Markov chains that are used for modeling both phenomena. Channel tap amplitude statistics are also provided, using the flexible Weibull probability density function (pdf). This pdf was found to best fit fading tap amplitude data, particularly for frequently observed severe fading, which is characterized by fade probabilities that are worse than the commonly used Rayleigh model. Fading parameters equivalent to Nakagami-m-model values ofmnear 0.7 were often observed (withm= 1 being Rayleigh and m < 1 being worse than Rayleigh). We also provide channel tap amplitude correlation coefficients, which typically range from 0.1 to 0.4 but occasionally take values greater than 0.7.

Updating Large Structure Model by the Sensitivity Analysis of FRF Correlation Functions.

Finite element (FE) model updating is an important tool to improve the accuracy of an initial FE model so that the predicted dynamic behavior matches as closely as possible that tested during the experiment. Two sets of new frequency response function (FRF) correlation functions, i. e. the amplitude correlation coefficient and the shape correlation coefficient are introduced, and an updating algorithm has been obtained by using the sensitivity of FRF correlation functions with respect to the selected design parameters. The use of physical parameters in model updating is implemented from a large ship model. The results indicate that this technique is feasible for very incomplete experimental FRF data and any updating frequency range, even in the case of measurement noise.

Spatial Correlation of a HF Wave Field in the Case of Oblique Reflection from the Ionosphere

We consider the spatial statistical characteristics of an HF signal and the interdependence of the correlation functions of the field amplitude and phase in the case of oblique reflection from the ionosphere. The amplitude and phase parameters are expressed either in terms of the parameter β of ionospheric turbidity, which can be determined most easily, or only in terms of the correlation coefficient of amplitudes at different points. We obtain the expressions for the amplitude and phase correlation functions, which describe well the experimental data.

Statistical Properties of Abr Amplitudes and Latencies Implications for Computation of Reference Limits and Relation to Click Phase

A method for statistical analysis and computation of reference limits for ABR latency and amplitude variables is presented. Condensation and rarefaction ABRs from 47 healthy controls aged 4-58 years were investigated. With respect to gaussianity of distributions, the square root transformation was superior to the logarithmic transformation for amplitudes, while the logarithmic transformation performed better for amplitude ratios. Wave V latency and the I-V interpeak latency were nearly normally distributed, while other latencies and inter-peak latencies displayed varying displacement from a normal distribution. Rarefaction ABR distributions were slightly closer to normality than were condensation ABRs. Amplitude vs. following amplitude and latency vs. amplitude correlation coefficients were larger for R than for C click ABRs; thus R clicks seem to evoke a better synchronized neural volley. Most of the correlation between amplitude and latency could be explained by the influence of age and sex. Hence, age and sex matched reference limits for ABR amplitudes, without correction for latency, seem to be adequate in practical clinical work.

Relation between red nucleus discharge and movement parameters in trained macaque monkeys.

Correlation and regression analyses were performed on thirty-three of the magnocellular red nucleus cells described in the previous paper. We sought to test for reliable relations between the parameters of individual tracking movements and corresponding bursts of neural discharge. High correlations were found between the following burst and movement parameters: (i) burst latency versus movement latency; (ii) burst duration versus movement duration; (iii) burst frequency versus movement velocity and (iv) number of spikes in the burst versus movement amplitude. Cells were ranked according to the average of the duration, velocity and amplitude correlation coefficients. The top twenty cells had average correlation coefficients ranging from 0.69 to 0.88 for their preferred movement. These cases were judged most likely to reveal the control functions of the red nucleus, and the following points refer to this sample. Burst onset led movement onset by 118 +/- 23 ms, and burst offset led movement offset by 50 +/- 38 ms. Burst duration increased as the duration of the movement increased (r = 0.87 +/- 0.11). The duration of the burst was approximately equal to movement duration (slope of 0.99 +/- 0.16) plus a constant (72 +/- 34 ms) throughout a broad range. Average discharge rate during the burst increased with average movement velocity (r = 0.69 +/- 0.15). The slope of the relation was 0.36 +/- 0.21 (pulses/s)/(deg/s) of joint rotation. The regression lines had consistent upward offsets (56 +/- 15 pulses/s) that exceeded the spontaneous discharge rate (17 +/- 10 pulses/s). The number of spikes in the burst increased with movement amplitude independent of velocity (r = 0.72 +/- 0.11). The slope of the relation was 0.62 spikes/deg and the offset was 13 +/- 4 spikes. The preferred movement was co-ordinated hand in fifteen cases, digit in three, elbow in one and shoulder in one. When these cells were tested with an alternate movement, the failure rate (cases in which a burst did not accompany a movement) increased from 1.4 to 20%, and the correlation coefficients generally were low and lacked significance. Cells in the top twenty had directionally specific responses, low variance in lead time, large depths of modulation (41-118 pulses/s) and low failure rates. Cells that failed to show strong parametric correlations often had one or more of the former attributes. It appears that high parametric correlations with individual movements are particularly restrictive criteria of relatedness.(ABSTRACT TRUNCATED AT 400 WORDS)