mehdi zamanian

The purpose of present study was to examine the effects of short time static and dynamic stretching of muscles on kinematics variability of lower extremity in healthy active males during cycling. 15 physical education and sport sciences male students from Kharazmi University voluntarily participated in this study. Subjects referred to the laboratory during two days, with 48 hours intervals between each sessions, and lower extremity kinematics data were collected from 30 pedaling cycle on the stationary cycle in 70 RPM in situation of without stretching, after 2, 5, and 10 minutes post stretching by means of motion analysis camera in 50 Hz frequency. Hip, knee and ankle joints angular displacement and velocity were extracted for constructing time series and variability calculation. Results of repeated measure ANOVA did not show any significant differences in angular displacement and velocity variability in hip, knee and ankle joints after 2, 5, and 10 minutes post stretching (P>0.05). Regarding results, probably it can be use static and dynamic stretching in warm up programs before cycling or rehabilitation on stationary cycle.

The present paper is aimed to analyze static deformation, natural frequency and subharmonic resonance of a bilayer cantilever microbeam, the second layer of which has a variable width and is located on a point along the microbeam's length. Electrostatic actuation is induced by applying the voltage between the microbeam and its opposite electrode. The importance of such configuration is revealed particularly in mass and pollutants micro-sensors. First, the nonlinear equation of motion, which has been extracted in previous studies using Hamilton's principle and considering the bending neutral axis shortening assumption, was rewritten for a microbeam with variable-width second layer. Then differential equations governing the static deflection and free vibration equation around the stability point are solved using Galerkin method. Three mode shapes of a doubled stepped-microbeam are employed as the comparison function. The shapes such as triangular, parabolic, symmetric parabolic and hyperbolic are considered for the second layer. In order to find the optimal length and thickness for the selected form, the relevant diagrams were plotted for static deformation and natural frequency at constant volume and different lengths and thicknesses, and then were analyzed and investigated. The discretized equations are solved by the perturbation theory. The excitation frequency is tuned near twice the fundamental natural frequencies (subharmonic excitation). The results show that system behavior depends on the size, position and width of the coated layer. The results of this paper can be used for optimum design of microsystems such as microswitches and mass and pollutant microsensors.

In this study, static deflection, natural frequency and nonlinear vibration in bi-layer clamped-clamped microbeam are investigated. In this configuration, the second layer is the viscoelastic layer which covers a part of the microbeam length. This model is the main element of many chemical microsensors. The governing equations of motion for the system are obtained by Lagrange method and discretized using the assumed mode method. The non-uniform micro-beam modes shape are used as the comparison function in the assumed mode method. Initially, considering the DC voltage, system static response and natural frequency around the static position are obtained. Then, considering the AC voltage, the dynamic response around the dynamic position is calculated by both analytical (perturbation method) and numerical methods (Rung-kutta) and compared for validation purposes. The effect of different geometrical parameters of the viscoelastic layer on the static and dynamic behaviors of the system is also analyzed. The results indicate that the dimensions and location of the viscoelastic layer significantly affect the static and dynamic behavior of the system. Therefore, by using this property and considering the application of microsensors, their behaviors can be made efficient. For sensors operating based on resonance frequency shift, the optimum shift of frequency state can be obtained by varying the dimensions and position of the viscoelastic layer. Moreover, time of response can be optimized when the system is operating based on changes in the capacity of a capacitor. The results also represent that convergence in the assumed mode method used in this paper is feasible even using a single mode, whereas in previous works and using the Galerkin method, convergence was fulfilled in the presence of 3 modes.

This paper investigates the optimal configuration for a partially two-layered circular capacitive microplate subjected to AC-DC electrostatic actuation. To this end, the static deflection due to DC electrostatic actuation, natural frequency of vibration about static position and primary resonance response due to AC electrostatic actuation are studied. Primarily, the nonlinear equations of motion are derived through classical laminated plate theory (CLPT). Then, the static position and natural frequency of vibration around static position are obtained using Galerkin approach. The linear mode shapes of non-uniform microplate i.e. a microplate coated as partial by a second layer are used as comparison functions. The forced vibration equations around static position are separated using Galerkin method, and solved by the multiple scale perturbation theory. Firstly, the impact of changes in the second layer radius on the variations of static and dynamic response of the system is studied while its thickness remains constant. Then, the effect of changes in the second layer thickness is studied while its radius remains constant. Finally, the impact of simultaneous change in the radius and thickness of the second layer is studied while its volume remains constant.

In this study, control design of a T shaped mass connected to the clamped-clamped microbeam excited by electrostatic actuation is investigated. The actuation force is generated by applying an electric voltage between the horizontal part of T shaped mass and an opposite electrode plate. In this model, the micro-beam is modeled by Euler-Bernoulli theory as a continuous beam. The T-shaped assembly connected to the the microbeam is assumed as a rigid body and nonlinear effect of electrostatic force is considered. Equations of motion and associated boundary condition are derived using the Lagrange’s principle. The differential equation of nonlinear vibration around the static position is discretized using Galerkin method.. The discretized equations are solved by the perturbation theory. To improve the dynamics behavior of systems, nonlinear control feedback has been presented. The controller regulates the pass band of microcantilever and analytically approximate the nonlinear resonance frequency and amplitudes of the periodic solutions when the microcantilever is subjected to one point and fully distributed feedback forces. The results of paper may be used for improving the design of mass sensors based on nonlinear jump phenomena.

Previous studies about the effect of static and dynamic stretching on forthcoming performance have been reported different results. In present study, it has been evaluated the effects of these two stretching on lower extremity muscular electrical activity using innovative nonlinear analysis methods. The purpose of present study was to examine nonlinear evaluation of local dynamic stability in lower extremity EMG after statics and dynamics stretching in active males during pedaling.
Fifteen physical education and sport sciences male students voluntarily participated in this study. Subjects referred to the laboratory during two days, with 48 hours intervals between each sessions, and EMG data from six lower extremity muscles were collected from 30 pedaling cycle on the stationary cycle in situation of without stretching, and after 2, 5 and 10 minutes post stretching. Filtered EMG data were extracted for constructing time series and Lyapunov Exponent (LyE) calculation.
Results of repeated measure ANOVA showed significant reduction in selected muscles EMG LyE during 2, 5 and 10 min post dynamic stretching compare to static stretching and no stretching conditions (p≤0.05).
Regarding results, probably it is better to use dynamic stretching versus static stretching in warm up programs before pedaling or rehabilitation on stationary cycle.

One of the main topics in the field of robotics is the motion control of wheeled mobile robots. Motion control encompasses trajectory tracking and point stabilization problems. In this paper these control problems will be considered for the tractor-trailer wheeled robots and a predictive control algorithm is developed for solving these problems. Therefore first kinematic model of the tractor_trailer robot is developed. Next, reference trajectories is produced for the system. Subsequently, predictive control law is designed for the trajectory tracking and point stabilization problems. Predictive control based on the known values of reference trajectories in the future, produces the control inputs in present time. Consequently the error signal with respect to the reference trajectory in future will be used in order to control the system at the present instant of time. This method is developed for solving the aforementioned control problems and is employed on the tractor_trailer wheeled robot. As can be seen from the results, the proposed control algorithm steer the wheeled robot asymptotically follow reference trajectories. Obtained results from the implementation of the proposed method for solving trajectory tracking and point stabilization problems, demonstrate the effectiveness of the presented algorithm.

The previous studies on the effect of statics and dynamics stretching on forthcoming performance have reported various results. The purpose of the present study was to examine the effects of static and dynamic stretching types of muscles on local dynamic stability in angular displacement of the lower extremity joints in active males during cycling using innovative nonlinear analysis methods.
A total of 15 male university students of physical education and sport sciences at Kharazmi University voluntarily participated in the current study. Participants referred to the laboratory twice on two days seperated by a 48-hour interval, and the lower extremity kinematics data was collected from 30 pedaling cycles on the stationary cycle in 70 RPM in conditions of of without stretching, and 2, 5, and 10 minutes after stretching by means of motion analysis camera in 50 Hz frequency. The angular displacement of hip, knee, and ankle joints were extracted by constructing time series and Lyapunov Exponent (LyE) calculation.
The results of repeated measure ANOVA did not show any significant differences in angular displacement LyE in hip, knee, and ankle joints 2, 5, and 10 minutes post stretching (P>0.05).
Considering the results, both static and dynamic stretching types can be used in warm up programs before pedaling on stationary cycle for the pruposes of training or rehabilitation.

The present Hamedanian dialect is the survival of corpus Hamedanian dialect, which can be found among the BabaTaher's pure and unchanged poems. In this study, some words of present Hamedanian dialect are discussed. Technically speaking, this paper can point out some Pahlavi terms and some other words with their ancient roots (Avesta, ancient Persian, and Sanskrit) which are not used in current Persian language.