حمید معین فرد

The aim of this study was to analyze the correspondence between the form identity and the content of sports advertisements with the strategic themes of the Iranian-Islamic model of progress.

The research was descriptive and survey method. The statistical population of this study was all sports management and marketing experts working in sports organizations and Isfahan municipality with a statistical population of 150 people. Based on Cohen (2000) formula, the sample size was estimated to be 108 people who were selected by stratified random sampling. Data were collected through a researcher-made questionnaire. In a pilot study based on the method of halving the data using Cronbach's alpha test, the reliability (α = 0.86) was reported. Also, face and content validity was confirmed by ten professors of sports management.

results indicate a significant difference between the current situation and the desired situation of matching the form identity, content, strategy of sports advertising with emphasis on the Iranian-Islamic model of progress (p <0.05).

The model written by the Iranian elite and emphasized by the Supreme Leader and can be followed by this significant difference between the form, content, identification and strategic approach of sports advertising with the concept of the Iranian-Islamic model of progress and its components (science, life, Thought and spirituality) prevented.Therefore, a suitable ground should be provided for the full recognition of this model by the officials of advertising organizations and its application in all dimensions. At the same time, a suitable platform should be provided for obtaining information and knowledge about the content of propaganda messages in which the concept of being Iranian and being Islamic can be seen. A suitable platform for accurate knowledge of culture and society should be provided so that it can move in a certain direction and direction based on it and have a suitable pattern to provide a platform where more components of advertising are known and information about it is accurate so that it can be used as a criterion for predicting changes. Although some views of the Iranian-Islamic model have been used in sports advertising, but those in charge tend to use attractive international symbols for the audience, so a suitable platform should be provided to better understand the concept of the Iranian-Islamic model of progress to the form and content of sports advertising. It led to the Iranian-Islamic concept.

In this paper, the dynamic behavior of a small-scale parallelogram (P) flexure is studied. First, using the beam constrain model and the modified strain gradient theory, the nonlinear strain energy of a small-scale beam is obtained in terms of its tip displacements. This energy expression is utilized to derive the strain energy of a P-flexure. Then the governing dynamic equations of motion are derived using Lagrange equations and are linearized around the operating equilibrium point. This linear model is employed to determine the allowable forces which do not lead to instability of the system. Moreover, the natural frequencies of the system are also extracted and the size effect as well as the static components of the applied loads on them are studied in detail. It is observed that by reducing the dimensions, the normalized transverse natural frequency of the system is increased. However, since there is no strain gradient in an axial mode, the axial normalized frequency is remained constant reducing the dimensions of the system. Moreover, it was observed that the tensile static forces lead to an increase, and transverse forces lead to a decrease in normalized natural frequency of the system. The procedure utilized for dynamic modeling of parallelogram flexures in this paper can be further extended for modeling more complex flexure systems.

Dual axis torsion micro-actuators find variety of applications such as optical switches, biomedical imaging and adaptive optics. Squeezed film air damping is one of the most important energy loss mechanisms in these devices. This damping, is a key factor in determination of the dynamic performance of the micro-electro-mechanical systems. So they have been widely considered by the researchers. The objective of this paper is to suggest a model for the squeezed film damping of dual axis torsional micro-actuators by considering the bending of the supporting torsion beams. To achieve so, the Reynolds equation governing the pressure of the trapped gas between the actuator plate and the underneath electrodes is considered and simplified for the case in which the inertial effects are negligible compared to the viscous effects. The dimensionless form of this equation is then solved using the extended Kantorovich method and the pressure distribution under the actuator is obtained. This pressure distribution is then employed to calculate the resulting force and force of the squeezed film air damping. The effects of the design parameters of the actuator on the dimensionless damping torques, dimensional damping torques and dimensional damping force are studied. The presented results in this paper can be effectively utilized for an accurate dynamic modeling and control of such structures.

The objective of the current study is to investigate the application of smart Magneto/Electro-Rheological (MR/ER) elastomers in vibration suppression and extending the stability region of the rotors system. The rotor is modeled via finite element method based on the Rayleigh beam theory. Proposed model takes the rotary inertia, gyroscopic effects and internal damping of the shaft into account. The stiffness and damping of the elastomers are considered as functions of the applied electric or magnetic fields. The simulation results reveal that the use of MR/ER elastomer leads to down shifting of the critical speeds and a reduction in its corresponding vibration amplitude. Also, the stability limit speed of the system is improved. Simulation results revealed that MR elastomer supports are superior on ER elastomer supports in the vibration suppression and extending the stability region of the rotor system. Finally, to improve the stability of the rotor system to higher operating rotational speeds, an on-off control strategy is employed. The proposed novel idea can be effectively utilized for optimization of the vibration level and widening the stability regions of rotating systems.

The goal of this paper is to study the large amplitude free vibration of wind turbine tower which modeled as a variable cross-section beam with eccentric mass. The effects of variable axial force due to gravity is also taken into account. The nonlinear governing equations of motion and the corresponding boundary conditions of the system are obtained using the Hamilton's principle as well as Euler-Bernoulli’s assumptions. Then a numerical finite difference scheme is utilized to find the natural frequencies and the mode shapes of the system. Using Galerkin method, the partial differential equations governing dynamic of the system are reduced to ordinary differential equations in terms of the end displacements which are coupled due to the presence of the transverse eccentricity. These temporal coupled ODEs are then solved analytically using the multiple time scales perturbation technique. The obtained analytical results are compared with the numerical ones and excellent agreement is observed. The results of this research can be used to study the effect of the eccentric tip mass, variable cross-section and gravity on the large amplitude vibration of wind turbine tower for improved dynamic performance.

The main objective of this paper is to propose an optimal fuzzy controller for suppressing the resulting vibration of an earthquake in a five floor building facilitated with magneto rheological damper. To this end, by utilizing the Hamilton’s principle, equations of motion of the system are derived based on a distributed parameter model. The mode shapes of the system are found by finite element simulations. A magneto rheological damper is used for each floor. To find the rule base of the fuzzy controller, a single degree of freedom vibratory system is considered and the rules derived from open loop simulations are utilized for controlling the vibration of the building. Spencer’s model is employed for analyzing the behavior of the magneto rheological damper. By recognizing the magneto rheological damper behavior as well as having the rule based obtained from single degree of freedom simulations, a fuzzy controller is designed to suppress the vibration of the building. Finally, the genetic algorithm is used to improve the performance of the proposed controller. Comparing the results of semi-active vibration control with passive-on and passive-off control strategies reveals that the suggested fuzzy controller can effectively reduce the amplitude of the vibration of the building.

A usual method in achieving a proper value for the ratio of constraint to degree of freedom stiffness in a compliant mechanism, is using an intermediate rigid element in its constitutive beams. This paper aims to study the nonlinear free vibration of a stiffened beam with a mass connected to its tip. Hamilton’s principle is used to find nonlinear partial differential equations governing behavior of the beam. The mode-shapes of the normalized and linearized system are then found analytically and verified via Abaqus simulations. Using a single mode approximation, the first mode-shape of the system is used along with the Lagrange equations to find governing ordinary differential equations of degree of freedom and degree of constraint dynamic. These equations are then solved numerically using MATLAB. The Discrete Fourier Transform of dynamic responses show that the degree of freedom dynamic contains a single dominant frequency, while the constraint dynamic contains three main harmonics. It is observed that dominant frequencies are essentially natural frequencies of the linearized system which are available in a closed form. The suggested analytical formulations as well as the proposed frequency analysis, is expected to provide an effective approach for analytical dynamic modeling of more complex compliant mechanisms.

Circular micro-plates are used in microelectromechanical systems (MEMS) such as micro-pumps and ultrasonic transducers due to their special geometry. One of the most important problems with electrostatic micro-actuators is pull-in instability which prevents large displacements. Stabilization in beyond pull-in displacements can be attained using an appropriate controller. This paper presents a position control problem for an electrostatic micro-actuator consisting two circular clamped micro-plates to enhance the stroke and speed up the input commands. To consider the modeling error and geometric uncertainties, a fuzzy controller is applied. First, the equation of the plates vibration is derived using Lagrange equation with single mode assumption. Fuzzy rule-base is constructed according to static and dynamic simulations. Genetic algorithm is utilized for finding the optimum parameters of the controller to accelerate accomplishing the commands. Finally, the maximum voltage of the plates is fitted with a function using the optimization results for full range gap commands. The performance of the fuzzy controller along with this function is depicted applying step, multiple step and chirp commands. The obtained results show that the objective has been met well.

In this paper, the vibration suppression capabilities of magnetorheological layer in smart beams is investigated. A three-layered beam including magnetorheological elastomer layer sandwiched between two elastic layers is considered. By assuming the properties of magnetorheological layer in the pre-yield region as viscoelastic materials behavior, the governing equations of motion and the corresponding boundary conditions are derived using Hamilton’s principle. Due to field-dependent shear modulus of magnetorheological layer, the stiffness and damping properties of the smart beam can be changed by application of magnetic field. This feature is utilized to suppress the unwanted vibration of the system. The appropriate magnetic field applied over the beam is chosen through a fuzzy controller for improving the transient response. The designed fuzzy controller uses the modal displacement and velocity of the beam as its inputs. The modal parameters of the sandwich beam including the natural frequencies and mode shapes are obtained and validated with existing results. Using the Galerkin method, the temporal equation governing beam’s motion is obtained and then the vibration of smart sandwich beam is investigated using numerical simulations. The results show that the magnetorheological layer along with the designed fuzzy controller can be effectively used to suppress the unwanted vibration of the system. The qualitative and quantitative knowledge resulting from this research is expected to enable the analysis, design and synthesis of smart beams for improving the dynamic performance of smart engineering structures.

In this study, the effects of frequency, height and wavelength of progressive gravity waves on vibration and energy absorption of the single- and two-degree of freedom Bristol oscillating cylinder systems have been investigated experimentally and numerically in different depth of water. The experiments were carried out in channel equipped with both a paddle-type wave-maker and wave features measurement tools. Numerical simulations were conducted in COMSOL software assigned to simulate interactions between physical environments for turbulent flow. Making a comparison between the numerical and experimental conclusions compared to the other researcher's results demonstrates a desired matching in a wide range of wave's parameters. It can be seen in findings that changing in depth of submerged objects from free surface of water has considerable influence on their vibration behavior, so that by rising in depth, the oscillations amplitude increases to a maximam and then decreases. The obtained results indicate the different effects of relative depth under the submerged buoy on the efficiency of the single- and two-degree of freedom systems; so that increasing water height causes rise in the efficiency of single degree of freedom systems, but it doesnt have considerable influence on two degree of freedom systems. The results also show that expanding the wave-maker frequency for a constant height of water in channel causes to rise in energy and height of the generated waves so that oscillations amplitude of submerged buoy rise in vertical and horizontal line.

Torsional micro-actuators have found variety of applications in optical switches, displays, interferometry, spectroscopy, abbreviation correction and biomedical imaging. In order to improve the performance of these systems, it is usually desirable to maximize their operating angle amplitude and their switching frequency. To reach this, the overshoot and the settling time of the system in following desired outputs should be minimized. The objective of this paper is to propose an optimal fuzzy controller to stabilize the angle of a torsion micro-actuator beyond its pull-in range. To do so, a dynamic model considering both rotational and translational degrees of freedom is considered. Using Lagrange equations, the differential equations of motion are derived. In the next step, the static behavior of the system is briefly reviewed. Also the effects of applied voltage and damping coefficient on both degrees of freedom are studied briefly. Based on the resulting understanding from the system, the required linguistic IF-THEN rules are derived. Using the famous combination of singleton fuzzifier, product inference engine and center average defuzzifier along with the fuzzy IF-THEN rules as the heart of the fuzzy system, a fuzzy controller is designed and simulated. The results show that the use of the designed controller and the closed-loop system can perfectly follow the commands either within or beyond the pull-in range with an acceptable overshoot and small settling time. It is expected that the designed controller be successfully utilized in analysis and optimization of torsional micro-actuators for better dynamic performance.

Dynamic modeling of beams under aerodynamic loading is extremely important in many engineering applications. So the objective of this paper is to present a new approach to model and simulate the time domain response of tapered cantilever beams with airfoil cross section to wind excitation. The extended Hamilton’s principles along with the Euler-Bernoulli assumptions are utilized to derive the Partial Differential Equation (PDE) governing the deflection of the beam. A new finite difference based algorithm is proposed for finding the mode-shapes as well as the natural frequencies of the beam. These mode-shapes are then used in a Galerkin projection procedure to convert the PDE governing the system’s behavior into strongly coupled nonlinear Ordinary Differential Equations (ODEs). The aerodynamic loadings are modeled using the open source code of XFOIL. The blade of an under developed 100KW wind turbine is considered as a case study. The results reveal that even a single mode approximation is accurate enough in predicting the beam’s dynamic exposed to wind excitation. It was also observed that the instability speed of beams with higher modal damping is considerably higher than those with lower modal damping. The knowledge resulting from this effort is expected to enable the analysis, optimization, and synthesis of tapered cantilever beams for improved dynamic performance.