Dynamic analysis of structures is of significant importance in a variety of applications. Modal parameters identification can be utilized in resonance frequency estimation, fault detection and its diagnostics in many industrial applications from automobile to aerospace and satellite industries. To perform the vibration tests utilizing shaker, test sample should be connected to shaker using fixture. No fixture can reproduce a perfectly rigid boundary condition; at some frequencies the interaction between the fixture and the structure will become important, causing the modes of the assembly to be considerably different from the fixed-base modes that would be predicted by an idealized finite element model. However, it would be very convenient to be able to estimate the fixed-base modes of a structure experimentally so they could be used to update or validate the model for the structure. In this paper, two degree of freedom model is considered for the system and optimal shape for fixture is designed based on the analytical analysis. Mode shapes and frequencies of fixture are investigated numerically and compared with experimental results. Effect of connection Torques on the system dynamics such as power spectral density and natural frequencies is studied by performing different experimental analyses.

An efficient capital market requires companies to provide quality financial information. It is also expected that with the development of the capital market, market participants pay more attention to the Information content of accounting. Therefore, the present study seeks to answer the question to what extent the Information content of accounting and capital market development are affected by each other? 207 companies were selected in the period of 2013-2019 using fixed and random effects method as well as Generalized torque estimator (GMM) and with the help of Stata software, the research hypotheses have been tested. To measure market development, three variables of stock market size, activity volume and turnover ratio were used and to calculate the Information content of accounting the model of Kevin et al. [29] has been used. The results of examining the hypotheses showed that both the variables of capital market development and the Information content of accounting have a positive effect on each other. Also, the development of the market in the past one and two periods has had a significant and positive effect on the development of the capital market in the current period, while the Information content of accounting of the past one and two periods do not have a significant impact on the content of current accounting information.

Introduction: Inequality of income distribution is one of the socio-economic issues of developing countries, including Iran. One of the proposed solutions to deal with this phenomenon is to reduce educational inequality. The purpose of this study is to investigate the effect of educational inequality on income inequality in the provinces of the country during the years 1380 to 1394. Method: In this study, fifteen-year historical data of Iranian provinces were used to achieve the goal by combined method. Gini coefficient data of education and education were collected from the yearbook of the Statistics Center of Iran and Mohaghegh Calculations and other data were collected from the Program and Budget Organization of each province. Income inequality was considered as a dependent variable and the educational inequality, the share of tax revenue from GDP and per capita income without oil were considered as independent variables. The model was estimated and analyzed using the Generalized torque technique and Eviews software. Findings: The estimation of the model showed that the effect of educational inequality on income inequality is U-shaped. That is, the first interval of educational inequality had a negative and significant effect on income inequality and the second power of the first interval of educational inequality had a positive and significant effect on income inequality. Also, the first interruption of government size had a positive and significant effect on the income inequality index, and the interruption of per capita income and the interruption of the share of provincial GDP tax on income inequality of Iran's provinces was negative and statistically significant. Discussion: Increasing educational inequality has reduced income inequality in the provinces of Iran over a period of fifteen years. The impact of educational inequality from the threshold of 0. 44 onwards has been on increasing income inequality. This means that educational inequality has increased income inequality (Gini coefficient) beyond the threshold.

In this research, in order to investigate the effect of the piezoelectric patch which is used as a sensor or actuator in rotating flexible structures such as a helicopter blade, the free vibrations of the rotating rectangular sheet with and without the piezoelectric patch have been presented. First-order shear deformation theory is considered for plate displacement and piezoelectric field. Considering the effect of Coriolis acceleration, centrifugal acceleration and centrifugal in-plane forces, the equations of motion are derived from Hamilton's principle and the electromechanical couple equation is obtained from Maxwell's equation. For piezoelectric, two electrical conditions, open circuit and closed circuit, which are used in sensors and actuators, respectively, have been considered. The equations are discretized with the help of the numerical method of Generalized differential squares and the matrices of inertia mass, eccentricity, Coriolis and stiffness matrix are obtained. Natural frequency values for beam and rotating plate have been compared in Abaqus software. Also, the values obtained from the numerical solution in MATLAB have been verified with articles and ABAQUS, which have high accuracy. The effect of parameters such as hub radius, rotation speed, sheet thickness, aspect ratio, piezoelectric patch thickness and applied voltage on the natural frequency of the system has also been investigated.

Shock absorption and reducing the Rate of Loading (ROL) during daily activities are considered as a reason for reducing the rate of injuries. Since, skeletal muscles utilize as shock absorber during weight bearing tasks, the purpose of this study was to examine the relationship between the maximum Torques of lower extremity muscles with the ROL during single leg drop landing. 33 men subjects (23±2years and 73±3 Kg) from Tarbiyat Moallem University of Tehran volunteered in this study. Maximum torque of lower extremity muscles and the Ground Reaction Forces (GRF) were measured by the Biodex system and force plate (AMTI), respectively. The Pearson correlation used to analyses the data at the a£0.05 threshold. The mean torque of the quadriceps, hamstring, plantar flexors, dorsi flexors, invertors and evertors muscled were 2.70, 1.75, 0.77, 0.43, 0.43, 0.40 Nm respectively, and the mean ROL was 519/60 N/ms. Significant correlations wasn't seen between maximum torque of lower extremity muscles with ROL. Due to results of this study it seem that quadriceps, hamstring, plantar flexors, dorsiflexors, invertors and evertors muscles have no role in decreasing the ROL in single leg drop landing.

Introduction: Handicapped people, who exclusively depend on manual wheelchair for locomotion, face great difficulties because they have constant pain in their upper-extremity members, mainly in the shoulder, elbow and the wrist. Manual propulsion can be considered a cyclical effort, thus the pains are symptoms of injuries from repetitive efforts.Purpose: The aim of this paper is to determine the dynamical efforts over the shoulder and elbow joints during the manual wheelchair propulsion using the Lagrange equations and the inverse dynamic techniques.Results: As a result, it is possible to establish a system of equations and thus evaluate the efforts over the joints. Another result is the possibility to simulate the system using the anthropometric values of real subjects aiming at making it easier to choose the best wheelchair.Discussion: Besides the study of the propulsion pattern, allows physical training aimed at improving the propulsion efficiency.

Introduction: The aim of this study was to determine the incidence of dentinal cracks in the mesial root of maxillary molar during canal preparation using Neoniti system in different torque settings.Materials & Methods: In this in-vitro study, 60 maxillary molars extracted for various reasons were selected. The teeth were divided into 4 groups: one group (n=15) without preparation was considered as a control group (unprepared control group), the other 3 groups prepared with rotary neoniti system: group with standard torque (1.5 N/CM2) (n=15), group with high torque (2N/CM2) (n=15), and group with low torque (1N /CM2) (n=15). After a canal preparation procedure, the teeth were horizontally sectioned at 3, 6 and 9 mm from the apex. All sections were examined for determining the presence of cracks using a stereomicroscope. Data were analyzed using chi-square test.Results: There was no crack in the control group. The number of cracks was significantly higher in the high-torque group (80%) than standard- and low-torque groups (20%, 26.7%, respectively) (p<0.001). However, no significant difference was found between the standard-torque group and low-torque group (p<0.001).Conclusion: According to this study result, to avoid crack formation in higher Torques using motors with torque control option is suggested.