Hardware implementation of Lorenz circuit systems for secure chaotic communication applications.

This paper presents the synchronization between the master and slave Lorenz chaotic systems by slide mode controller (SMC)-based technique. A proportional-integral (PI) switching surface is proposed to simplify the task of assigning the performance of the closed-loop error system in sliding mode. Then, extending the concept of equivalent control and using some basic electronic components, a secure communication system is constructed. Experimental results show the feasibility of synchronizing two Lorenz circuits via the proposed SMC. 

Synchronization of Chaotic Systems and Its Application in Security Terminal Sensing Node of Internet of Things.

Recently, with the rapid development of data and information, it has become necessary to establish secure communications and appropriate security services to ensure a secure information exchange process. Therefore, to protect the privacy and confidentiality of private data, in this research, we use the Lorenz chaotic system to generate chaotic signals and apply them to the encryption of the communication of the Internet of Things (IoT) terminal sensor nodes. In addition, we design a simple proportional-integral-derivative (PID) controller and a quasi-sliding mode controller (QSMC) to synchronize the master-slave chaotic systems for decrypting the signals. Then, we encrypt the environmental signals measured from the IoT node at the transmitting side (master) and send them to the receiving side (slave). After the receiving side receives the encrypted signals, it decrypts them with the PID controller. Thus, the security of IoT information can be assured and realized.

Comparison of Plantar Pressure Distribution between Different Speed and Incline During Treadmill Jogging.

The aim of this study was to examine the effect of changes in speed and incline slope on plantar pressure distribution of the foot during treadmill jogging. Plantar pressure parameters were measured with the Pedar-X system in twenty healthy girls (mean age of 20.7 years, mean height of 1.60m, and a mean weight of 53.35kg). Because variations in walking speed or slope can significantly change the magnitude of plantar pressure, comparisons of plantar pressure distribution between the two independent protocols during treadmill jogging were considered in this study. First, the subjects ran at the same speed of 2 m·s(-1) with different incline slopes of 0%, 5%, 10%, and 15%. Second, they ran on the same slope of 0% with different speeds of 1.5 m·s(-1), 2.0 m·s(-1), and 2.5 m·s(-1). The peak pressure of the eight plantar surface areas, apart from the medial forefoot and the hallux, significantly increased (p < 0.05) with an increase of 33% of peak pressure from 1.5 m·s(-1) to 2.5 m·s(-1) (speed) at heel region. In contrast, the peak pressures at the heel, medial fore-foot, toe and hallux decreased significantly (p < 0. 05) with increasing incline slope. At the heel, peak pressure reduced by 27% from 0% to 15% incline, however, pressure at the lateral midfoot region increased as following. Different speeds and incline slopes during jogging were associated with changes in plantar pressures. By systematic investigation of foot kinematics and plantar pressure during jogging with varying incline slope and speed, the results of this study provided further insight into foot biomechanics during jogging. Key pointsThe study aimed to compare the plantar pressure distribution of the foot between different incline and speed during treadmill jogging by using plantar insole measurement system.With the increase of speed, apart from the hallux and medical forefoot, the peak pressure of all regions was raised significantly.As the slope increased, there was reduced peak pressure of the heel, medial forefoot, and hallux and toes.

Stability analysis of Takagi-Sugeno fuzzy cellular neural networks with time-varying delays.

This correspondence investigates the global exponential stability problem of Takagi-Sugeno fuzzy cellular neural networks with time-varying delays (TSFDCNNs). Based on the Lyapunov-Krasovskii functional theory and linear matrix inequality technique, a less conservative delay-dependent stability criterion is derived to guarantee the exponential stability of TSFDCNNs. By constructing a Lyapunov-Krasovskii functional, the supplementary requirement that the time derivative of time-varying delays must be smaller than one is released in the proposed delay-dependent stability criterion. Two illustrative examples are provided to verify the effectiveness of the proposed results.

Design and implementation of EP-based PID controller for chaos synchronization of Rikitake circuit systems.

This article addresses an evolutionary programming (EP) algorithm technique-based and proportional-integral-derivative (PID) control methods are established to guarantee synchronization of the master and slave Rikitake chaotic systems. For PID synchronous control, the evolutionary programming (EP) algorithm is used to find the optimal PID controller parameters kp, ki, kd by integrated absolute error (IAE) method for the convergence conditions. In order to verify the system performance, the basic electronic components containing operational amplifiers (OPAs), resistors, and capacitors are used to implement the proposed chaotic Rikitake systems. Finally, the experimental results validate the proposed Rikitake chaotic synchronization approach.

Underlying mechanisms of Tai-Chi-Chuan training for improving balance ability in the elders.

OBJECTIVE: To compare balance ability between elderly individuals who practiced Tai-Chi-Chuan (TCC) for average 9.64 years and elderly individuals who did not practice TCC and its relationship with lower extremity muscle strength and ankle proprioception. METHODS: Twenty-five elderly volunteers were divided into two groups according to their TCC practcing experience. Sixteen were TCC group and the other nine were control population. Subjects completed a static balance test and ankle proprioception test using a custom-designed evaluation system, and concentric and eccentric knee extensor and flexor muscle strength tests. Subjects stood on the plate form to measure the proprioception in functional standing position which was differed from the previous studies. Multiple linear regressions were also used to predict the important factor affecting balance. RESULTS: TCC group performed better than the control group in balance, proprioception, and muscle strength of lower extremity. The proprioception was the most important factor related to balance ability and it can be accounted for explaining 44% of variance in medial-lateral sway direction, and 53% of variance in antero-posterior sway direction. The proprioception may be a more important factor which affecting the balance ability. CONCLUSION: TCC training is recommended to the elders; as it can improve balance ability through better proprioception.

Ultrasound imaging evaluation of abdominal muscles after breast reconstruction with a unilateral pedicled transverse rectus abdominis myocutaneous flap.

BACKGROUND: A muscle-sparing (MS) procedure using a full-width pedicled transverse rectus abdominis (RA) myocutaneous (TRAM) flap was developed to reduce abdominal morbidities after breast reconstruction. However, the effects of this procedure on the morphology of the remnant RA muscle and other abdominal muscles remain unclear. OBJECTIVE: Ultrasound imaging was used to evaluate the morphology of the remnant RA muscle and other abdominal muscles in women with the MS pedicled TRAM flap procedure. DESIGN: A case-control, cross-sectional design was used. METHODS: Thirty-four women with an MS unilateral pedicled TRAM flap procedure after mastectomy (TRAM group) and 25 women who were healthy and matched for age (control group) participated. The curl-up test measured trunk flexor muscle strength. Ultrasound imaging measured the thickness of all abdominal muscles in all participants and the cross-sectional area of the RA muscle at rest and in an isometric position with the head raised in women in the TRAM group. Acoustic echogenicity and border visibility assessed the tissue composition of the remnant RA muscle. RESULTS: Trunk flexor muscle strength was weaker in the TRAM group than in the control group. Compared with the remnant RA muscle in the contracted state, the remnant RA muscle in the relaxed state was thinner and had a smaller cross-sectional area. The remnant RA muscle in the relaxed state also was thinner, more echoic, and less visible than its contralateral counterpart. No differences in the thickness of the other abdominal muscles were found between the sides. The abdominal muscles in the TRAM group were smaller than those in the control group. LIMITATION: Because a prospective, longitudinal design was not used, a definite cause-effect relationship could not be determined. CONCLUSIONS: In women with an MS unilateral pedicled TRAM flap procedure, the remnant RA muscle retains its ability to change in size during contraction, albeit at reduced levels. Muscular atrophy occurs in other ipsilateral and contralateral abdominal muscles as well as the remnant RA muscle. Postoperative immobilization is the most likely cause of generalized weakness of the abdominal musculature.

Three-dimensional characteristics of neck movements in subjects with mechanical neck disorder.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To examine characteristics of neck movement at three-dimensional planes for subjects with mechanical neck disorder (MND) and measure cervical range of motion, coupling motion, and calculation of the upper cervical rotation ratio. BACKGROUND: MND is characterized by symptoms of neck pain, headache, dizziness and limited range of motion (ROM). However, the characteristics of neck movements across the three-dimensional planes in MND patients remain unknown. METHODS: Forty participants were recruited, which consisted of twenty-seven subjects with MND and 13 healthy subjects. A three-dimensional electromagnetic motion capture device with custom data analysis software was used to measure the neutral position of the neck and the range of motion of upper and lower cervical spine. RESULTS: The results indicate that subjects with MND had significantly decreased ROM in right rotation (p< 0.05) and extension (p< 0.05) movements compared to the healthy group. Increased coupling motion (p< 0.05) in the rotation plane during cervical flexion was also found in the MND group compared to control group. For rotations in neutral or in flexion positions, rotation to the right showed smaller range of motion compared to rotation to the left. CONCLUSION: In this study, MND was associated with altered cervical movement patterns with increases in coupling motion. The findings may help to differentiate MND from whiplash-associated disorder. Increasing upper cervical spine rotation mobility may be crucial for treating deficiencies in neck rotation in patients with MND.

Comparison of the electromyographic activation level and unilateral selectivity of erector spinae during different selected movements.

For patients with scoliosis, core stabilization exercises may be beneficial in improving muscle strength and trunk dynamic control. However, few studies have examined whether the erector spinae (ES) activation status during unilateral spinal extensor strengthening meets the guideline for patients with spinal scoliosis. To determine ES activation and whether unilateral selectivity shows a significant difference in the three designated exercises, we recorded the ES activity of 20 university students during these exercises. All participants had normal spinal flexibility without a history of, or current, spinal disease. The three stabilization exercise movements were quadruped, prone, and modified prone. We detected the activation level of bilateral ES using electromyography and normalized it with the maximum voluntary contraction. We determined unilateral selectivity by the ratio of the activation level between active and nonactive ES. The results showed that the modified prone movement caused the greatest muscle activity up to 41.6% of maximum voluntary contraction among other muscles (P<0.05). The quadruped and modified prone movements showed greater differences in bilateral sides (P<0.05) with a unilateral selectivity of 1.72 and 1.67, respectively. However, there was no significant difference in unilateral selectivity between quadruped and modified prone movements. Quadruped movement may be more suitable than the other two only for unilateral back extensor training. Nevertheless, for improvement in muscle strength, modified prone movement could also be considered.

Stability analysis of neural networks with interval time-varying delays.

The global exponential stability is investigated for neural networks with interval time-varying delays. Based on the Leibniz-Newton formula and linear matrix inequality technique, delay-dependent stability criteria are proposed to guarantee the exponential stability of neural networks with interval time-varying delays. Some numerical examples and comparisons are provided to show that the proposed results significantly improve the allowable upper and lower bounds of delays over some existing ones in the literature.

Correlation between the length and weight of Arius maculatus off the southwestern coast of Taiwan

In this study, Arius maculatus were collected using the samples caught by bottom trawling off the southwestern coast of Taiwan. Length-weight and length-length, fork (FL), standard (SL) and total (TL) lengths, relationships were determined. The relationships between the lengths were all significantly linear (p<0.01), the b value in the length-weight relationship for this value was significantly lower than 3 in the fall (p<0.01), when the temporal changes were taken into account, indicating that only the sampling time affected the growth pattern of A. maculatus. The growth was isometric in the spring, summer and winter, but it was negative and allometric in the fall.