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In this paper, results of  inelastic displacement ratios based on earthquake ground motions of Iran are presented. These ratios are calculated for single degree of freedom systems with elastic perfectly plastic behavior model and various strength reduction factors subjected to 204 earthquake ground motion records. These records are recorded on firm soil sites of Iran and have following characteristics 1) Recorded in earthquakes with seismic moment magnitude larger than 5,  2) At least one of the two horizontal components of records has peak ground acceleration larger than 50 cm/s², 3) Recorded in free field stations so that potential soil-structure interaction effects omitted,  4) Records with hypo central distance larger than 15 km so that near fault effects omitted,  5) Recorded on soil conditions 1, 2 and 3 according to spectral ratio H/V of ground motions,  6) Records in which band pass range in correction process were at least between 0.33 to 20 Hz.  204 acceleration time histories including 70, 30 and 104 acceleration time histories related to soil condition 1, 2 and 3 respectively are used. In this statistical study, 422688 inelastic displacement ratios (related to 204 acceleration time histories, 296 period of vibration and 7 strength reduction factors) from response of SDOF systems with elastic perfectly plastic behavior model are calculated. Mean values of inelastic displacement ratios for each period of vibration and each strength reduction factor subjected to all 204 earthquake records and their dispersions are presented. The influence of period of vibration, strength reduction factor, soil condition, earthquake magnitude and hypocentral distance on inelastic displacement ratios are evaluated. This ratio in short period of vibration is larger than unit (maximum inelastic displacement larger than maximum elastic displacement) and for long period of vibration is close to unit (maximum inelastic displacement nearly equal to maximum elastic displacement). Soil condition effects on inelastic displacement ratio, for period of vibration larger than 1.5 second is very small and neglectable but neglecting of soil condition in periods between 0.4 and 1.5 second cause error up to 20 percent and for periods smaller than 0.4 second cause error up to 40 percent in estimation of inelastic displacement ratio. Neglecting of distance effects to focal of earthquakes in estimation of inelastic displacement ratio, for period of vibration smaller than 1 second, causes error up to maximum 20 percent. This error increase when strength reduction factor increases. For period of vibration larger than 1 second, neglecting of distance effect doesn’t make considerable error. Neglecting of magnitude effects of earthquakes in estimation of inelastic displacement ratio, for period of vibration smaller than 1 second, causes error up to maximum 60 percent. This error increase when strength reduction factor increases. For period of vibration larger than 1 second, neglecting of distance effect doesn’t make considerable error. By using of nonlinear regression analysis, a simplified equation based on mean results is calculated and Maximum inelastic displacement of single degree of freedom systems on Iran firm sites could be estimated using proposed equation and maximum elastic displacement demand. Finally, proposed equation is compared with C₁ coefficient of target displacement in FEMA440.

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Automotive crankshafts are subjected to fluctuating torques due to periodic strokes in the cylinder. The gas-forces and inertial-forces due to the reciprocating masses will contribute to the excitation forces on the crankshaft system. The forces cause alternative torque on the crankshaft and cause vibration on the motor which cause noise and shake in the vehicle. Therefore, it’s necessary that was determined crankshaft dynamic behaviour. Although most physical structures are continuous, their behaviour can usually be represented by a discrete parameter model. In this paper, torsional vibration was determined with theoretical, analytical and experimental analysis on the Peugeot and Renault vehicle. For Solution of theoretical analysis, was used of B.I.C.E.R.A formula [1] and natural frequency for analytical analysis obtained with ANSYS software. Then, theoretical and analytical procedure compared with the experimental model, to obtain optimization model and with the best model, influence of torsional vibration was determined on the engine speed.

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In the present research, hydrodynamical and aerodynamical characteristics of a high-speed planning hull is studied using computational fluid dynamics. Simulations are three-dimensional with considering a two-phase turbulent flow. To obtain sinkage and trim of the hull, two degrees of freedom is assumed for it. Rigid body dynamic equations and governing equations of the fluid are coupled using 6DOF solver and dynamic mesh technique. Based on the available experimental results, simulations of the aimed high speed hull are performed in the linear velocity range of 0.9-8.31 m/s. Comparing the present numerical results with the experimental data, shows that maximum average error for resistance, trim and sinkage in different velocities does not exceed 10%. This shows the accuracy and proficiency of the current model. Mesh independency of solutions is studied for all velocities and the results are reported based on the most suitable mesh. At the end, the effect of applying steps on reducing the drag and improving stability of the hull is investigated for several states in one and two steps. Finally, the most optimized state is introduced and relating results are given. Results show that applying steps to the mentioned high speed hull reduce the overall resistance by 11%.

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In this paper, a robust linear quadratic regulator (LQR) based Reinforcement learning method is designed for a four degree of freedom inverted pendulum. The considered system contains a four degree of freedom inverted pendulum with a concentrated mass at the tip of it. The bottom of inverted pendulum is moved in x-y plane in x and y directions. For tracking control of two angles of inverted pendulum, two plane forces are applied in x and y directions at the bottom of pendulum. The governing equations of the system are derived using the Lagrange method and then a robust linear quadratic regulator (LQR) based Reinforcement learning controller is designed. The inverted pendulum is learned for a range of different angles, different lengths and different masses. The parametric uncertainties are defined as various lengths and masses of inverted pendulum and the disturbances are defined as impact and continuous forces which are applied on the inverted pendulum. After learning, the controller can learn online the system for any arbitrary angle, length, mass or disturbance which are not learned in the defined range. Numerical results show that the good performance of the reinforcement learning controller for the inverted pendulum in the presence of structural and parametric uncertainties, impact and continuous disturbances and sensor noises.

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Seismic design codes provide different equations for estimating displacement demands in various buildings and structures. Such equations were usually obtained by performing regression analysis over the obtained data from numerical models under different nonlinear analyzes. On the other hand, the application of artificial earthquakes is allowed to be considered for design and demand assessment in structures when there is a lack of suitable ground motions for a specific region and site. Since the accuracy of such relations affects the reliability of demand estimating in structures, it is required to assess the efficiency of such predictive relations. Moreover, it is essential to assess the efficiency of those relations for artificially generated earthquakes. Hence, in this study, the estimated demands from the design and assessment codes relations are evaluated for artificially generated ground motions. In this regard, regulations in the fourth edition of the Iranian seismic design code (also known as Standard 2800) and the last revision of the Iranian seismic evaluation code of practice (also known as Code-360) are considered. Estimated demands from these codes are compared to the results from the nonlinear time-history analysis of a group of single degree of freedom (SDOF) systems. Although an SDOF system can not represent the complete behavior of a complex building, for the low to medium-rise buildings with a fundamental vibration first mode, such an idealization is acceptable. In this regard, a group of SDOF systems with the elastic-perfectly-plastic (EPP) nonlinear behavior was considered. SDOF systems have vibration periods between 0.1s to 2.0s (as low to medium-rise buildings) with strength reduction factors (R_μ) of 2 to 8 to cover most of the common lateral resisting systems. These systems were analyzed under the action of 24 artificially generated ground motion records. Earthquake records were generated based on three different envelop shapes including compound shape, exponential shape, and Saragoni and Hart shape. These envelop shapes are representing the general form of an earthquake accelerogram and try to impose the real characteristics of an earthquake on the generated record. After employing the time-history analysis on each SDOF system, the mean of the maximum displacement demands of SDOF systems was obtained and compared to those from the estimating equations in Standard 2800 and Code-360. It is observed that estimated demands from Standard 2800 are closer to those from time-history analysis when compared with the obtained results from Code-360. Among the considered strength reduction factors, it was observed that SDOF systems with larger R_μ lead to a higher difference between the time-history results and those from codes. This is more predominant over the period range of 0.1s to 0.8s. So, relations in both codes are required to be modified for better demand estimating. In this regard, a method is proposed for modifying the available equations in the prementioned codes to accurately predict the displacement demands in systems under the action of artificially generated ground motions. A comparison between the results from the modified equations and those from the nonlinear time-history analysis shows the efficiency of the proposed method.