A new butterfly-shaped chaotic attractor

AbstractIn this paper, a new chaotic system is proposed that consists of six terms including one multiplier and one quadratic term. The characteristics of this system are examined by theoretical and numerical analysis, such as equilibria, their stabilities, Lyapunov exponents and Lyapunov dimension, dissipativity, as well as, Poincaré maps, bifurcations, waveforms, power spectrums are performed. In addition, the forming mechanisms of compound structures of the new chaotic attractor are investigated

Development of a new equation of state for water and its applications : Parts I & II

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Includes bibliographical references.by Pyung-Hun Chang.M.S

Control and synchronization of the generalized Lorenz system with mismatched uncertainties using backstepping technique and time‐delay estimation

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140007/1/cta2353.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140007/2/cta2353_am.pd

The ascending reticular activating system from pontine reticular formation to the thalamus in the human brain

Introduction: Action of the ascending reticular activating system (ARAS) on the cerebral cortex is responsible for achievement of consciousness. In this study, we attempted to reconstruct the lower single component of the ARAS from the reticular formation (RF) to the thalamus in the normal human brain using diffusion tensor imaging (DTI). Methods: Twenty six normal healthy subjects were recruited for this study. A 1.5-T scanner was used for scanning of diffusion tensor images, and the lower single component of the ARAS was reconstructed using FMRIB software. We utilized two ROIs for reconstruction of the lower single component of the ARAS: the seed ROI - the RF of the pons at the level of the trigeminal nerve entry zone, the target ROI - the intralaminar nuclei of the thalamus at the level of the commissural plane. Results: The reconstructed ARAS originated from the pontine RF, ascended through the mesencephalic tegmentum just posterior to the red nucleus, and then terminated on the intralaminar nuclei of the thalamus. No significant differences in fractional anisotropy, mean diffusivity, and tract number were observed between hemispheres (P>0.05) Conclusion: We reconstructed the lower single component of the ARAS from the RF to the thalamus in the human brain using DTI. The results of this study might be of value for the diagnosis and prognosis of patients with impaired consciousness. © 2013 Yeo, Chang and Jang.1

The cortical activation pattern by a rehabilitation robotic hand: a functional NIRS study

Introduction: Clarification of the relationship between external stimuli and brain response has been an important topic in neuroscience and brain rehabilitation. In the current study, using functional near infrared spectroscopy (fNIRS), we attempted to investigate cortical activation patterns generated during execution of a rehabilitation robotic hand. Methods: Ten normal subjects were recruited for this study. Passive movements of the right fingers were performed using a rehabilitation robotic hand at a frequency of 0.5 Hz. We measured values of oxy-hemoglobin (HbO), deoxy-hemoglobin (HbR) and total-hemoglobin (HbT) in five regions of interest: the primary sensory-motor cortex (SM1), hand somatotopy of the contralateral SM1, supplementary motor area (SMA), premotor cortex (PMC), and prefrontal cortex (PFC). Results: HbO and HbT values indicated significant activation in the left SM1, left SMA, left PMC, and left PFC during execution of the rehabilitation robotic hand (uncorrected, p < 0.01). By contrast, HbR value indicated significant activation only in the hand somatotopic area of the left SM1 (uncorrected, p < 0.01). Conclusions: Our results appear to indicate that execution of the rehabilitation robotic hand could induce cortical activation. © 2014 Chang, Lee, Gu, Lee, Jin, Yeo, Seo and Jang.1

Cortical activation change induced by neuromuscular electrical stimulation during hand movements: a functional NIRS study

Objectives. Neuromuscular electrical stimulation (NMES) has been used in the field of rehabilitation for a long time. Previous studies on NMES have focused on the peripheral effect, in contrast, relatively little is known about the effect on the cerebral cortex. In the current study, we attempted to investigate the change of cortical activation pattern induced by NMES during execution of hand movements in normal subjects, using functional near infrared spectroscopy (fNIRS). Methods. Twelve healthy normal subjects were randomly assigned to the NMES group (six subjects) and the sham group (six subjects). We measured oxy-hemoglobin (HbO) in six regions of interest (ROI) during pre-NMES and post-NMES motor phase; the left dorsolateral and ventrolateral prefrontal cortex, premotor cortex, primary sensory-motor cortex (SM1), hand somatotopic area of SM1, and posterior parietal cortex. Between the pre-NMES and the post-NMES motor phases, real or sham NMES was applied on finger and wrist extensors of all subjects during a period of 5 minutes. Results: In all groups, during the pre-NMES motor phase, the HbO value in the hand somatotopic area of the left SM1 was higher than those of other ROIs. In the NMES group, during the post-NMES motor phase, HbO value variation in the hand somatotopic area of the left SM1 showed a significant decrease, compared with that of sham group (p < 0.05). However, in the sham group, similar aspect of results in HbO values of all ROIs was observed between pre-NMES and post-NMES motor phases (p > 0.05). Conclusions: Results of this study showed that NMES induced a decrease of cortical activation during execution of hand movements. This finding appears to indicate that application of NMES can increase the efficiency of the cerebral cortex during execution of motor tasks. © 2014 Jang et al.; licensee BioMed Central Ltd.1

Introduction and synchronization of a five-term chaotic system with an absolute-value term

We propose a new chaotic system that consists of only five terms, including one multiplier and one quadratic term, and one absolute-value term. It is observed that the absolute-value term results in intensifying chaoticity and complexity. The characteristics of the proposed system are investigated by theoretical and numerical tools such as equilibria, stability, Lyapunov exponents, Kaplan-Yorke dimension, frequency spectrum, Poincaré maps, and bifurcation diagrams. The existence of homoclinic and heteroclinic orbits of the proposed system is also studied by a theoretical analysis. Furthermore, synchronization of this system is achieved with a simple technique proposed by Kim et al. (Nonlinear Dyn., 2013, in press) for a practical application. © 2013 Springer Science+Business Media Dordrecht.

Enhanced Operational Space Formulation for Multiple Tasks by Using Time-Delay Estimation

The operational space formulation (OSF) has been enhanced from a practical viewpoint through the application of the time-delay estimation (TDE). In principle, the OSF enables an excellent decentralized control owing to its ability to achieve dynamic consistency. In reality, however, it can suffer from modeling errors and relatively large computational demands. As a remedy for these problems, the OSF has been combined with the TDE, which is known for its accurate estimation of robot dynamics with high computational efficiency. By virtue of the TDE, the OSF with the TDE (OSFTDE) shows enhanced accuracy in terms of dynamic consistency and control performance along with enhanced computational efficiency. Through simple but obvious simulations and experiments, the OSFTDE shows much better accuracy than the OSF with modeling error of 5 or higher, although accuracy is slightly worse than the OSF with a perfect model, thereby demonstrating its practical advantages. © 2004-2012 IEEE.