Ming-Chung Ho

Synchronization of two different systems by using generalized active control

We have already generalized the techniques from active control theory, and applied them to synchronize two different systems. In this Letter, we demonstrate these techniques by period-system, Lorenz and Rossler systems. Moreover, the effect of external noise is also included in our discussion.

Phase and anti-phase synchronization of two chaotic systems by using active control

Using techniques from active control theory, we demonstrate that two coupled chaotic systems can be phase and anti-phase synchronized. The techniques are applied to Lorenz, Rossler, and Chen systems.  2002 Elsevier Science B.V. All rights reserved.

Age-related changes of task-specific brain activity in normal aging

An important question in healthcare for older patients is whether age-related changes in cortical reorganization can be measured with advancing age. This study investigated the factors behind such age-related changes, using time-frequency analysis of event-related potentials (ERPs). We hypothesized that brain rhythms was affected by age-related changes, which could be reflected in the ERP indices. An oddball task was conducted in two experimental groups, namely young participants (N=15; mean age 23.7±2.8 years) and older participants (N=15; mean age 70.1±7.9 years). Two types of stimuli were used: the target (1 kHz frequency) and standard (2 kHz frequency). We scrutinized three ERP indices: event-related spectral power (ERPSP), inter-trial phase-locking (ITPL), and event-related cross-phase coherence (ERPCOH). Both groups performed equally well for correct response rate. However, the results revealed a statistically significant age difference for inter-trial comparison. Compared with the young, the older participants showed the following age-related changes: (a) power activity decreased; however, an increase was found only in the late (P3, 280-450 ms) theta (4-7 Hz) component over the bilateral frontal and temporo-frontal areas; (b) low phase-locking in the early (N1, 80-140 ms) theta band over the parietal/frontal (right) regions appeared; (c) the functional connections decreased in the alpha (7-13 Hz) and beta (13-30 Hz) bands, but no difference emerged in the theta band between the two groups. These results indicate that age-related changes in task-specific brain activity for a normal aging population can be depicted using the three ERP indices.

SYNCHRONIZATION OF UNCERTAIN HYPERCHAOTIC AND CHAOTIC SYSTEMS BY ADAPTIVE CONTROL

This paper presents the synchronization between uncertain hyperchaotic and chaotic systems. Based on Lyapunov stability theory, an adaptive controller is derived to achieve synchronization of hyperchaotic and chaotic systems, including the case of unknown parameters in these two systems. The T.N.C. hyperchaotic oscillator is used as the master system, and the Rossler system is used as the slave system. Numerical simulations verify these results. Additionally, the effect of noise is investigated by measuring the mean squared error (MSE) of two systems.

Age‐ and disease‐related features of task‐related brain oscillations by using mutual information

The aim of this study was to investigate changes in task‐related brain oscillations and corticocortical connections in patients with mild cognitive impairment (MCI) and those with normal aging using cross‐mutual information (CMI) analysis. We hypothesized that task‐related brain oscillations and corticocortical connections were affected by age‐ and disease‐related changes, which could be reflected in the CMI analysis. Electroencephalogram (EEG) recordings were measured in 16 MCI patients, 15 healthy age‐matched controls, and 16 healthy younger individuals. The frequencies and interhemispheric CMI data were estimated in all groups. The specific EEG rhythms measured were delta (δ), theta (θ), alpha (α), beta (β), and gamma (γ) bands. Significant differences in δ, θ, α, and β bands were observed between the younger and elderly groups. However, only the θ band was significantly different between the elderly and MCI groups. Moreover, this study used EEG recordings to investigate age‐ and disease‐related changes in the corticocortical connections of the brain. This study proves that the θ‐band frequency of the connection between the parietal and occipital lobes for the age‐ and disease‐related changes can be depicted using the CMI analysis.

Experimental observations of dual-polarization oscillations in laser-diode-pumped wide-aperture thin-slice Nd:GdVO 4 lasers

Dual-polarization oscillations (DPO) on different transitions have been observed for the first time in a mirror-coated thin-slice Nd:GdVO(4) laser possessing a large fluorescence anisotropy with laser-diode (LD) pumping. Oscillation spectra, input-output characteristics, pump-dependent pattern formations and noise power spectra are studied experimentally. Simultaneous oscillations of orthogonally-polarized different (higher-order) transverse modes and the resultant violation of inherent antiphase dynamics in multimode lasers have been demonstrated. The experimental results have been explained in terms of the reduced three-dimensional cross-saturation of population inversions among orthogonally-polarized modes peculiar to LD-pumped wide-aperture anisotropic lasers, in which a pumped area is larger than a lasing beam diameter.

Solving Reality Problems by Using Mutual Information Analysis

Cross-mutual information (CMI) can calculate to time series for thousands of sampled points from corticocortical connection among different functional states of brain in Alzheimer’s disease (AD) patients. The aim of this study was to use mutual information analysis in the multichannel EEG to predict the probability of AD disease. Considering the correlation between AD disease and ageing effect, the participants were 9 AD patients and 45 normal cases involving teenagers, young people and elders. This data revealed that both right frontal and temporo-parietal are differences between normal and AD participants. Besides, this study found the theta band is the main frequency to separate AD patients from all participants. Furthermore, this study suggested a higher distinguishable method by mutual information to predict the possibility AD patients.

Detect AD Patients by Using EEG Coherence Analysis

The purpose of this study is to discriminate mild Alzheimers disease (AD) patients from the normal aging. The EEG coherence was applied to analyze the data from auditory oddball paradigm to discriminate the differences of corticocortical connections between mild AD patients and healthy subjects. The results showed that the lower values of coherence were performed in mild AD patients than in the normal aging subjects, especially in theta band. The implications and suggestions are shown in this study.

Creating the desired output waveform in nonlinear oscillators with modulations

Abstract We explore the possibility of creating the desired periodic output waveform in nonlinear oscillators with modulations. For a theoretic example, we show that the desired periodic output waveform can be created in a forced Duffing-Holmes oscillator. Our study may provide a way toward a goal-oriented scheme of controlling chaos based on periodic perturbations.

Using Sidereal Rotation Period Expressions to Calculate the Sun’s Rotation Period through Observation of Sunspots

We utilize sidereal rotation period expressions to calculate the sun’s rotation period via sunspot observation. From the well-known astronomical sites, we collected sunspot diagrams for 14 months, from January 2013 to February 2014, to analyze, compare, and implement statistical research. In addition to acquiring the average angular rate of the movement of sunspots, we found that even the same number of sunspots moved at different angular rates, and generally the life of larger sunspots is longer than 10 days. Therefore the larger sunspots moved around the back of the sun, and a handful of relatively smaller sunspots disappeared within a few days. The results show that the solar rotation period varied with the latitude. However, if we take the average of the sunspots at high and low latitudes, we find that the calculated value is very close to the accredited values.